HK1249126B - Polyurethane adhesive layers for electro-optic assemblies - Google Patents

Description

Polyurethane adhesive layers for electro-optical components

Citation of Related Applications

This application claims priority to U.S. Application No. 62/235,480, filed September 30, 2015, and U.S. Application No. 62/235,580, filed October 1, 2015. The entire contents of both of these applications, as well as all other U.S. patents and published and co-pending applications referenced below, are incorporated herein by reference in their entirety.

background

Polyurethane has purposes in many kinds of applications, for example, as adhesive.Adhesive can be used for electro-optical assembly, and wherein electro-optical assembly comprises a plurality of functional layers usually, and can be used for forming display, as electrophoretic display.Such assembly can comprise electro-optical material layer, front plate and back plate.Electro-optical material has at least two display states usually when different electric fields are applied to this material, and at least one optical property (for example light transmittance, reflectivity, luminescence) of described at least two display states is different.Electro-optical display can have the attribute of good brightness and contrast, wide viewing angle, bistability and low power consumption.

In some cases, electro-optical assembly utilizes adhesive that different layers are adhered together (for example, electro-optical material layer is adhered to front plate and/or back plate).Such adhesive is normally known in the art, and can comprise for example hot melt adhesive and/or wet coating adhesive, such as polyurethane-based adhesive.Adhesive requires good adhesion strength usually, has the specific property (for example electrical property, mechanical property, thermal property) that does not hinder the operation of electro-optical display simultaneously.Yet, still need to have the adhesive of improved character.

Overview

The present invention is a polyurethane adhesive material for electro-optical components. The polyurethane adhesive generally comprises at least an end-capped cyclic carbonate group, but it may comprise additional functional elements and/or a cross-linking agent. In some embodiments, the adhesive is formed by two or more curing steps. Each curing step may comprise, for example, cross-linking of the adhesive, thermoplastic drying of the adhesive, end-capping of the adhesive, chain extension of the adhesive, and/or a combination thereof, so that the adhesive undergoes at least one curing step.

In one aspect, a polyurethane adhesive layer for an electro-optical assembly is disclosed. In some embodiments, the polyurethane has cyclic carbonate end-capping groups. In some embodiments, the adhesive comprises polyurethane and acrylic acid functional groups. In some embodiments, the adhesive comprises a first reactive functional group and a second reactive functional group, wherein at least one of the reactive functional groups has a dipole moment greater than about 2 debyes.

Other aspects and various non-limiting embodiments of the present invention are described in the detailed description below. In the event that this specification and the documents incorporated by reference include contradictory and/or inconsistent disclosures, this specification shall prevail. If two or more documents incorporated by reference include contradictory and/or inconsistent disclosures, the document with the later effective date shall prevail.

Brief description of the accompanying drawings

Various aspects and embodiments of the present application will be described with reference to the following drawings.It should be understood that the drawings are not necessarily drawn to scale.

1A-1E are schematic diagrams of electro-optical assemblies including adhesive layers.

FIG. 2 illustrates capping agents that may be used to create an adhesion layer for an electro-optical assembly.

FIG. 3 illustrates chain extension agents that can be used to create adhesive layers for electro-optical assemblies.

FIG. 4 illustrates a reaction that may be used to cure an adhesive layer in an electro-optical assembly.

5A is a graph of the tuned white state (WS) 30 second image stability of an experimental polyurethane overcoated on an electro-optical layer.

5B is a graph of the tuned dark state (DS) 30 second image stability trace of an experimental polyurethane overcoated on an electro-optical layer.

6 is a graph of the adjusted 30 second white state (WS) image stability of adhesives having various levels of cyclic carbonate end groups (CCARB) overcoated to an electro-optical layer.

Figure 7 is a graph of the adjusted 30 second WS L* drift versus the mole percentage of cyclic carbonate end-groups for an adhesive overcoated to an electro-optic layer. Figure 7 demonstrates the optimal range of cyclic carbonates that reduce the 30 second WS L* drift.

8 is a graph of the drift in adjusted 30 second WS image stability for pyrrolidone (HEP) and cyclic carbonate (CCARB) adhesives overcoated on an electro-optic layer.

Figure 9 is a graph of WS L* versus pulse length for a standard aqueous polyurethane dispersion adhesive (control) and a cyclic carbonate polyurethane adhesive with acid functionality (CCARB/acid). According to one set of embodiments, both adhesives were overcoated to an electro-optical layer compared to an aqueous polyurethane dispersion laminated to the same ink (control).

10 is a graph of the white state (WS) shift (L*δWS) of L* at 25° C. versus electrical stress time for polyurethane adhesive layers containing various functional groups.

11 is a graph of WS 30 second adjusted image stability traces of cyclic carbonate polyurethane (CCARB) coated at low and high dry adhesive coat weights compared to a commercial waterborne polyurethane dispersion adhesive coated at approximately 4 mils.

Figure 12 shows the storage (G') and loss (G") shear modulus curves at 1 Hz for hybrid polyurethane adhesives cured through Stage I ("first cure") and Stage II ("second cure").

Figure 13 is an SEM micrograph at 100x magnification of an electrode/electro-optical layer/adhesive layer stack coated with a mixed adhesive at 8 g/ ^m2 after curing. This micrograph illustrates that the adhesive layer can be applied with good planarity and minimal increase in the overall thickness of the stack.

FIG. 14 is a SEM micrograph at 1000× magnification of an electrode/electro-optical layer/adhesive layer stack coated with a mixed adhesive at 8 g/m ² after curing.

FIG15 shows an exemplary scheme for reacting polyurethane (PU) with a cross-linking agent.

16 is a graph of storage (G′) and loss (G″) shear modulus curves at 1 Hz for uncured and cured (via Stage II) cross-linked cyclic carbonate polyurethane (X-CCARB) adhesives.

17A-17B are SEM micrographs at 100x and 1000x magnification, respectively, of an electrode/electro-optic layer/adhesive layer stack coated with a cross-linked cyclic carbonate polyurethane at 7 g/m ² after curing, illustrating that the overall thickness of the electro-optic layer is only minimally increased with the inclusion of the adhesive.

Other aspects, embodiments, and features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.

Details

The present invention includes a new polyurethane adhesive layer of a class, which is very suitable for being added to electro-optical components, for example in the electrophoretic display of encapsulation. The polyurethane adhesive comprises at least a cyclic carbonate group usually, yet it can comprise other functional elements and/or cross-linking agents. In some embodiments, the adhesive is formed by two or more curing steps. Each curing step can comprise for example crosslinking of adhesive, thermoplastic drying of adhesive, end-capping of adhesive, chain extension of adhesive and/or its combination, so that this adhesive undergoes at least one solidification in each curing step.

Adhesive can comprise at least one type of end-capping agent and/or at least one type of chain extension agent.In certain embodiments, adhesive comprises two or more reactive functional groups (for example, is designed to react with one or more curing materials so that for example at least one of these two or more reactive functional groups forms a cured portion, such as a crosslinked reactive functional group). In some cases, adhesive comprises acrylic acid. In certain embodiments, adhesive is a mixed adhesive (for example, comprising polyurethane and acrylic acid mixed adhesive) for comprising two or more types of adhesive materials. In some embodiments, adhesive is formed by curing two or more adhesive materials under two groups of different conditions. For example, in an exemplary embodiment, adhesive comprises the acrylic acid cured by thermoplastic drying, and the polyurethane cured by reacting with this acrylic acid (for example, by with acrylic acid crosslinking).

Also generally provide the method for forming adhesive and adhesive layer.In some embodiments, the method comprises by making one or more reactive functional groups and one or more curing material reaction (for example, make adhesive and the first curing material reaction, then make adhesive and the second curing material reaction) come curing adhesive.For example, curing adhesive can comprise by making one or more reactive functional groups and curing material such as cross-linking reagent reaction and crosslinking adhesive.Reactive functional group and curing material type are described in more detail in this article.In some cases, curing adhesive can comprise the crosslinking of adhesive, the thermoplastic drying of adhesive, the end blocking of adhesive, the chain extension and/or its combination of adhesive.In certain embodiments, curing adhesive comprises the first curing step and the second curing step (for example, wherein each curing step comprises making reactive functional group and one or more curing material reaction).In some cases, after the first curing step and before the second curing step, substrate (for example peeling layer, electro-optical layer) is adhered to adhesive.

Adhesives can be used in many applications, including but not limited to materials for electro-optical components (e.g., as adhesive layers). Electro-optical components can form electro-optical displays, such as electrophoretic displays. As described above, electro-optical components typically include multiple functional layers, including but not limited to a front plate electrode (e.g., which may include a polymer film coated with a conductive material), a back plate electrode (e.g., which may include electrodes, circuitry, and/or a support layer), and an electro-optical material layer. The electro-optical material layer may include an electro-optical material having a first and a second display state, wherein at least one optical property (e.g., transmittance, reflectivity, luminescence) of the first and second display states is different, and the material is caused to change from its first display state to its second display state by applying an electric field to the material. For example, in some electrophoretic displays, the electro-optical material layer may include a plurality of capsules distributed in a binder. The capsules may include a clear fluid in which charged ink particles (e.g., black and white ink particles) are suspended. The ink particles shift within the capsules in response to the electric field to produce a displayed image.

The term "electro-optical" as applied to a material or display is used herein in its conventional sense in the field of imaging to refer to a material having first and second display states that differ in at least one optical property, the material being changed from its first display state to its second display state by application of an electric field to the material. While the optical property is typically color as perceived by the human eye, it may also be another optical property, such as light transmission, reflectivity, and luminescence, or, in the case of displays intended for machine reading, a false color in the sense of altered reflectivity at electromagnetic wavelengths outside the visible range.

The term "gray state" is used herein in its conventional sense in the field of imaging to refer to a state intermediate between two extreme optical states of a pixel, and does not necessarily imply a black-to-white transition between the two extreme states. For example, several of the E Ink patents and published applications cited herein describe electrophoretic displays (EPIDs) in which the extreme states are white and dark blue, such that the intermediate "gray state" will actually be light blue. In fact, as already mentioned, the change in optical state may not be a color change at all. The terms "black" and "white" may be used hereinafter to refer to the two extreme optical states of a display, and should be understood to generally include extreme optical states that are not strictly black and white, such as the white state and dark blue state described above. The term "monochrome" may be used hereinafter to refer to a drive scheme that drives a pixel only to its two extreme optical states, without an intermediate gray state.

The terms "bistable" and "bistability" are used herein in their conventional sense in the art to refer to a display comprising display elements having first and second display states that differ in at least one optical property, such that after any given element is driven to assume its first or second display state by an addressing pulse of finite duration, that state persists after termination of the addressing pulse for at least several times, for example, at least four times, the minimum duration of the addressing pulse required to change the state of the display element. U.S. Patent No. 7,170,670 shows that some particle-based electrophoretic displays capable of displaying grayscale are stable not only in their extreme black and white states, but also in their intermediate gray states, as is true for some other types of electro-optical displays. Although, for convenience, the term "bistable" may be used herein to cover both bistable and multistable displays, such displays are properly referred to as "multistable" rather than "bistable."

Several types of electro-optical displays are known. One type of electro-optical display is a rotating two-color component type, such as described in the 5th, 808,783, 5,777,782, 5,760,761, 6,054,071, 6,055,091, 6,097,531, 6,128,124, 6,137,467 and 6,147,791 United States Patents (although this type of display is usually referred to as a "rotating two-color ball" display, the term "rotating two-color component" is more accurate and preferred because in some of the above-mentioned patents, the rotating component is not spherical). This display uses a large amount of small bodies (small bodies) (usually spherical or cylindrical), which have two or more parts with different optical properties and an internal dipole. These small bodies are suspended in a liquid-filled vacuole in the matrix, and these vacuoles are filled with liquid so that the small body can rotate freely. The appearance of the display is changed by applying an electric field to the display, thereby rotating the body to various positions and changing which parts of the body are seen through the viewing surface. This type of electro-optical medium is generally bistable.

Another type of electro-optical display uses an electrochromic medium, such as an electrochromic medium in the form of a nanochromic film comprising an electrode formed at least in part from a semiconducting metal oxide and a plurality of dye molecules attached to the electrode that are capable of reversibly changing color; see, for example, O'Regan, B. et al., Nature 1991, 353, 737; and Wood, D., Information Display, 18(3), 24 (March 2002). See also Bach, U. et al., Adv. Mater., 2002, 14(11), 845. This type of nanochromic film is also described in, for example, U.S. Patents Nos. 6,301,038, 6,870,657, and 6,950,220. This type of medium is also typically bistable.

Another type of electro-optical display is the electrowetting display developed by Philips and described in Hayes, R.A. et al., "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425, 383-385 (2003). In U.S. Patent No. 7,420,549, it was shown that such an electrowetting display can be made bistable.

One type of electro-optical display that has been the subject of intensive research and development for many years is the particle-based electrophoretic display (EPD), in which multiple charged particles migrate through a fluid under the influence of an electric field. Compared to liquid crystal displays (LCDs), EPDs can offer excellent brightness and contrast, wide viewing angles, bistability, and low power consumption. However, issues with the long-term image quality of these displays have hindered their widespread adoption. For example, the particles that make up EPDs tend to settle, resulting in a short service life for these displays.

As mentioned above, electrophoretic media require the presence of a fluid. In most prior art electrophoretic media, this fluid is a liquid, but electrophoretic media can be produced using gaseous fluids; see, for example, Kitamura, T. et al., "Electrical toner movement for electronic paper-like display," IDW Japan, 2001, Paper HCS1-1, and Yamaguchi, Y. et al., "Toner display using insulative particles charged triboelectrically," IDW Japan, 2001, Paper AMD4-4. See also U.S. Patents Nos. 7,321,459 and 7,236,291. When the medium is used in an orientation that allows such sedimentation to occur, such as in a billboard disposed in a vertical plane, such gas-based electrophoretic media appear to be susceptible to the same types of problems caused by particle sedimentation as liquid-based electrophoretic media. In fact, particle sedimentation presents a more serious problem in gas-based electrophoretic media than in liquid-based electrophoretic media because the viscosity of the gaseous suspending fluid is lower than that of the liquid suspending fluid, causing the electrophoretic particles to sediment more quickly.

Numerous patents and applications assigned to or in the names of the Massachusetts Institute of Technology (MIT) and Iink Corporation describe various technologies for encapsulated electrophoretic and other electro-optical media. Such encapsulated media comprise a plurality of small capsules, each of which itself comprises an inner phase of electrophoretically mobile particles contained in a fluid medium and a capsule wall surrounding the inner phase. Typically, the capsules themselves are held in a polymer binder to form an adhesion layer positioned between two electrodes. The technologies described in these patents and applications include:

(a) electrophoretic particles, fluids, and fluid additives; see, for example, U.S. Patent Nos. 7,002,728 and 7,679,814;

(b) capsules, adhesives, and encapsulation processes; see, e.g., U.S. Patent Nos. 6,922,276 and 7,411,719;

(c) Films and subassemblies comprising electro-optical materials; see, for example, U.S. Patent Nos. 6,982,178 and 7,839,564;

(d) Backsheets, adhesive layers, and other auxiliary layers and methods for use in displays; see, for example, U.S. Patent Nos. 7,116,318 and 7,535,624;

(e) color formation and color adjustment; see, e.g., U.S. Patent No. 7,075,502 and U.S. Published Patent Application No. 2007/0109219;

(f) Display applications; see, for example, U.S. Patent No. 7,312,784 and U.S. Published Patent Application No. 2006/0279527; and

(g) Non-electrophoretic displays, such as those described in US Pat. Nos. 6,241,921, 6,950,220, 7,420,549, and US Published Patent Application No. 2009/0046082.

Many of the aforementioned patents and applications recognize that in encapsulated electrophoretic media, the walls surrounding discrete microcapsules can be replaced by a continuous phase, thereby creating so-called polymer-dispersed electrophoretic displays (PDEPIDs), wherein the electrophoretic medium comprises a plurality of discrete electrophoretic fluid droplets and a continuous phase of polymer material, and wherein the discrete electrophoretic fluid droplets in such PDEPIDs can be considered capsules or microcapsules, even though discrete capsule membranes are not associated with each individual droplet; see, for example, the aforementioned U.S. Patent No. 6,866,760. Therefore, for the purposes of this application, such polymer-dispersed electrophoretic media are considered a subcategory of encapsulated electrophoretic media.

A related type of electrophoretic display is the so-called "microcell electrophoretic display." In a microcell electrophoretic display, charged particles and fluids are not encapsulated in microcapsules, but rather are held in a plurality of cavities formed in a carrier medium, typically a polymer film. See, for example, U.S. Patents Nos. 6,672,921 and 6,788,449 assigned to Sipix Imaging.

Although electrophoretic media are typically opaque (because, for example, in many electrophoretic media, the particles substantially block visible light from passing through the display) and operate in a reflective mode, many electrophoretic displays can be made to operate in a so-called "shutter mode," in which one display state is substantially opaque and one display state is light-transmissive. See, for example, U.S. Patents Nos. 5,872,552, 6,130,774, 6,144,361, 6,172,798, 6,271,823, 6,225,971, and 6,184,856. Dielectric electrophoretic displays, which are similar to electrophoretic displays but rely on variations in electric field strength, can operate in a similar mode; see U.S. Patent No. 4,418,346. Other types of electro-optical displays can also operate in a shutter mode. Electro-optical media operating in shutter mode may be used in multilayer structures for full color displays; in such structures, at least one layer adjacent to the viewing surface of the display is operated in shutter mode to expose or hide a second layer further from the viewing surface.

Encapsulated electrophoretic displays generally do not suffer from the aggregation and sedimentation failure modes of conventional electrophoretic devices, and also offer additional advantages, such as the ability to print or coat the display on a wide variety of flexible and rigid substrates (the use of the word "printing" is intended to include all forms of printing and coating, including but not limited to: pre-metered coating, such as patch die coating, slot or extrusion coating, slope or step coating, curtain coating; roll coating, such as knife-on-roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; screen printing processes; electrostatic printing processes; thermal printing processes; inkjet printing processes; electrophoretic deposition (see U.S. Patent No. 7,339,715); and other similar technologies). Thus, the resulting display can be flexible. Moreover, because the display medium can be printed (using a variety of methods), the display itself can be manufactured inexpensively.

Other types of electro-optic media can also be used in the displays of the present invention. The bi-stable or multi-stable behavior of particle-based electro-optic displays and other electro-optic displays that exhibit similar behavior (for convenience, such displays may be referred to hereinafter as "impulse-driven displays") contrasts sharply with the bi-stable or multi-stable behavior of conventional liquid crystal ("LC") displays. Twisted nematic liquid crystals are not bi-stable or multi-stable, but rather act as voltage sensors, such that applying a given electric field to a pixel of such a display produces a specific gray level at that pixel, regardless of the gray level previously present at that pixel. Furthermore, LC displays can be driven in only one direction (from non-transmissive or "dark" to transmissive or "bright"); the reverse transition from a lighter state to a darker state is affected by reducing or eliminating the electric field. Finally, the gray level of a pixel in an LC display is not sensitive to the polarity of the electric field, but only to its magnitude, and in practice, for technical reasons, commercial LC displays often reverse the polarity of the driving electric field at relatively frequent intervals. In contrast, a bistable electro-optical display acts essentially as a pulsed switch, so that the final state of a pixel depends not only on the applied electric field and the time the field is applied, but also on the state of the pixel before the field was applied.

Regardless of whether the electro-optical medium used is bi-stable, to achieve high-resolution displays, individual pixels of the display must be addressable without interference from adjacent pixels. One way to achieve this is to provide an array of nonlinear elements, such as transistors or diodes, with at least one nonlinear element associated with each pixel, forming an "active matrix" display. The addressing or pixel electrode that addresses a pixel is connected to a suitable voltage supply via the associated nonlinear element. Typically, when the nonlinear element is a transistor, the pixel electrode is connected to the drain of the transistor, and this configuration will be presented in the following description, but it is essentially arbitrary and the pixel electrode can be connected to the source of the transistor. Typically, in high-resolution arrays, the pixels are arranged in a two-dimensional array of rows and columns, so that any particular pixel is uniquely defined by the intersection of a particular row and a particular column. The sources of all transistors in each column are connected to a single column electrode, while the gates of all transistors in each row are connected to a single row electrode; again, the assignment of sources to rows and gates to columns is conventional but essentially arbitrary and can be reversed if desired. The row electrodes are connected to a row driver, which essentially ensures that only one row is selected at any given moment, i.e., a voltage is applied to the selected row electrode to ensure that all transistors in the selected row are conducting, while voltages are applied to the other rows to ensure that all transistors in these unselected rows remain non-conducting. The column electrodes are connected to a column driver, which applies a selected voltage to each column electrode to drive the pixels in the selected row to their desired optical state (the aforementioned voltages are related to a common front electrode, which is usually located on the side of the electro-optical medium opposite the non-linear array and extends across the entire display). After a pre-selection time interval called the "line addressing time", the selected row is deselected, the next row is selected, and the voltage on the column driver is changed to allow the next row of the display to be written. This process is repeated to allow the entire display to be written in a row-by-row manner.

Adhesive layer can be used for the layer of display being joined together.For example, in some embodiments, use adhesive layer that front plate electrode and/or back plate electrode are adhered to electro-optic material layer.As used herein, electro-optic material layer can also be referred to as electro-optic medium, ink or ink layer.Adhesive can comprise polymer (for example polyurethane), and it can solidify with heat, chemical and/or optical mode.As described further below, in some embodiments, adhesive comprises polyurethane, and described polyurethane comprises the end-capping agent that causes some performance enhancement of selection.In some embodiments, end-capping agent comprises cyclic carbonate.In some embodiments, end-capping agent comprises the end-capping agent of first type and the end-capping agent of second type.

The use of adhesives comprising two or more curing portions (formed in two or more steps) can provide several advantages over conventional adhesives. In some embodiments, the improved rheology of the adhesive system can form an adhesive coating on a layer (e.g., an electro-optical layer, such as an air-dried side having a relatively rough surface compared to a smooth peel-off side ("SSL")) that results in reduced coating weight, reduced ink-adhesive coating thickness, improved display resolution, improved low-temperature dynamic range, thinner coatings for flexible applications, and reduced void and/or defect formation compared to the use of an adhesive having only one curing portion. In certain embodiments, improved performance of electro-optical components has been observed using embodiments in which the adhesive is dual cured to form the electro-optical component, including, but not limited to, reduced white state L* loss over time, increased dynamic range, improved low-temperature operation (e.g., improved dynamic range), and increased volume resistivity, compared to application by hot melt. In contrast, conventional adhesives may suffer from poor low-temperature performance, poor rheology, and may have electrical properties (e.g., resistivity) that reduce the functionality of the electro-optical material layer (e.g., reduced switching efficiency).

As used herein, term "curing part" generally refers to the physical connection (such as covalent bond, non-covalent bond, etc.) between two or more polymer backbones.Term main chain has its typical meaning in this field, and generally refers to a series of covalently bonded atoms that produce a continuous chain together to form a polymer, and generally does not refer to any side chain (such as side chain) or cross-linked group.In some cases, curing part can include crosslinking (such as the reaction of two or more reactive functional groups and a cross-linking agent).In exemplary embodiments, curing part is formed by reacting reactive functional group, curing material (such as cross-linking agent) and the second reactive functional group so that the first reactive functional group and the second reactive functional group are connected and formed by the curing material.In certain embodiments, the first reactive functional group and the second reactive functional group are reactive functional groups of the same type.In some cases, the first reactive functional group and the second reactive functional group can be different types of reactive functional groups. In some embodiments, the solidified material is connected to the first reactive functional group and/or the second reactive functional group by a key, such as an ionic bond, a covalent bond, a hydrogen bond, a van der Waals interaction, etc. The covalent bond can be, for example, carbon-carbon, carbon-oxygen, oxygen-silicon, sulfur-sulfur, phosphorus-nitrogen, carbon-nitrogen, metal-oxygen or other covalent bonds. The hydrogen bond can be, for example, between hydroxyl, amine, carboxyl, sulfhydryl and/or similar functional groups.

In another exemplary embodiment, the cured portion is formed by thermoplastically drying the binder material such that two or more polymer backbones interact to form bonds (e.g., through intermolecular forces such as hydrogen bonding, dipole-dipole, etc.). For example, in some cases, an acrylic acid (e.g., polyacrylic acid) polymer can be dried (e.g., by applying heat to the binder material(s)) such that two or more reactive functional groups on the polymer backbone undergo a thermoplastic reaction (e.g., by removing water and increasing the glass transition temperature (Tg) of the binder material (e.g., an amorphous binder material), and forming a bond between the two reactive functional groups), thereby forming a cured portion that connects the original polymer backbone.

In yet another embodiment, the polyurethane-acrylic hybrid adhesive is cured in a first step by thermoplastic drying followed by curing in which crosslinks are produced between reactive species on the polymer backbone of the polyurethane and reactive species on the acrylic backbone.

In some embodiments in which the adhesive is formed by two or more curing steps, the adhesive comprises two or more types of cured parts. For example, in some embodiments, the adhesive comprises a first type of cured part containing a first crosslink (formed by the reaction of a first crosslinking reagent with two or more reactive substances), and a second type of cured part containing a second crosslink (formed by the reaction of a second crosslinking reagent with two or more reactive substances). In some cases, the first and second crosslinking reagents can be the same or different. In another embodiment, the adhesive can comprise a first type of cured part containing a first crosslink, and a second type of cured part containing a thermoplastic bond.

As used herein, the term "curing material" generally refers to a compound that promotes a reaction between two or more reactive functional groups, resulting in the linkage of the reactive functional groups. In some cases, the curing material can be a cross-linking agent. As described above, the reaction of the curing material with the two or more reactive functional groups can form a cured portion.

As shown in FIG1A , in some embodiments, the electro-optical assembly 100 includes a backplate electrode 110, a frontplate electrode 130, and an electro-optical material layer 120. As described above, the various layers of the assembly can be bonded together with an adhesive layer 140. In some embodiments, as shown in FIG1A and FIG1B , the backplate electrode 110 is adhered to the electro-optical material layer via an adhesive layer 140. In some embodiments, as shown in FIG1B , the frontplate electrode 130 is adhered to the electro-optical material layer 120 via an adhesive layer 142, which can comprise the same or different adhesive as the adhesive layer 140. As shown in FIG1C , the electro-optical material layer 125 can include capsules 150 and a binder 160, which will be described in more detail below. The capsules 150 can encapsulate one or more particles that can be moved by applying an electric field across the electro-optical material layer 125. In some such embodiments, the frontplate electrode 130 can be adjacent to the electro-optical material layer 125, and the backplate electrode 110 is adhered to the electro-optical material layer via the adhesive layer 140. In an exemplary embodiment, as shown in FIG1D , backplate electrode 110 may be adhered to electro-optic material layer 125 via adhesive layer 140, and frontplate electrode 130 may be adhered to electro-optic material layer 125 via adhesive layer 142. In another exemplary embodiment, as shown in FIG1E , frontplate electrode 130 may be adhered to electro-optic material layer 125 via adhesive layer 140, and backplate electrode 110 may be adhered to electro-optic material layer 125 via adhesive layer 142.

It should be understood that the adhesive layer can be used to adhere any type and number of layers to one or more other layers in the assembly, and that the assembly may include one or more additional layers not shown in the drawings. Additionally, while Figures 1C-1E illustrate encapsulated electro-optical media, the adhesive layer can be used with a variety of electro-optical components, such as liquid crystal, frustrated internal reflection, and light emitting diode components.

Except urethane of the present invention, adhesive layer can comprise other component.The limiting examples of suitable component comprises other urethane, acrylic acid, alkyd, epoxide, amine and siloxane.In some cases, adhesive layer can comprise the similar adhesive material (for example two types of acrylic acid, acrylic acid and alkyd, urethane and siloxane, two types of urethane, urethane and acrylic acid) of two or more types.

In some embodiments, the adhesive is provided in the form of a dispersion (e.g., an aqueous dispersion). For example, in some cases, the adhesive dispersion can be used directly in a coating method and/or by using a reactive monomer solution in an adhesive dispersion or solution to form an adhesive layer as described herein. In some cases, the aqueous dispersion contains water, which can be removed (e.g., by applying heat) after the adhesive is deposited on one or more surfaces.

Typically, polyurethane is prepared by an addition polymerization method involving diisocyanates. Non-limiting examples of polyurethane include polyether polyurethane, polyester polyurethane, polyether polyurea, polyurea, polyester polyurea, polyester polyurea, polyisocyanate (e.g., polyurethane comprising isocyanate bonds) and polycarbodiimide (e.g., polyurethane comprising carbodiimide bonds). However, typically polyurethane contains urethane groups. The polyurethanes for use in the components and methods described herein can be prepared using methods known in the art. Typically, isocyanate-terminated polyurethanes are formed by the reaction of at least one diisocyanate compound with a second reagent (e.g., a polyol) comprising at least two groups that can react with isocyanate groups. In some embodiments, polyurethane is a linear polymer formed by the reaction of a diisocyanate compound with a second reagent (e.g., a diol) comprising two groups that can react with isocyanate groups. After preparing the isocyanate-terminated polyurethane, the terminal isocyanate groups can be deactivated by reaction with a terminating reagent, thereby forming a blocked polyurethane (e.g., such that the polyurethane and/or terminal isocyanate groups do not undergo further reaction). For example, after preparing an isocyanate-terminated polyurethane, the terminal isocyanate group can be blocked by reacting with one or more blocking agents, thereby forming a blocked polyurethane. In some cases, the isocyanate-terminated polyurethane can be dispersed in water by reacting with a neutralizing agent, such as neutralized when stabilized by ionic groups. In some embodiments, the molecular weight of the polyurethane can be controlled by adding at least one type of blocking agent. Blocking agents are described in more detail below and can also be used to prepare other adhesives. Polyurethanes (such as isocyanate-terminated polyurethanes, blocked polyurethanes and/or neutralized polyurethanes) can also optionally be chain extended by reacting with a chain extender. Although the above steps can be performed sequentially as described above, in alternative embodiments, the order of the steps can be varied and/or more steps can be performed simultaneously. For example, in some embodiments, a polyurethane can be formed by providing a mixture of at least one diisocyanate, a second reagent comprising at least two groups that can react with isocyanate groups, and one or more blocking agents, and reacting the mixture substantially simultaneously. In some cases, one or more blocking agents are added after reacting a mixture comprising at least one diisocyanate and a second agent comprising at least two groups reactive with isocyanate groups. The blocking agent can be added during and/or after the mixture reacts (e.g., after reacting as described herein).

In some embodiments, isocyanate-terminated polyurethane is formed by the reaction of at least one diisocyanate compound and at least one difunctional polyol or at least one multifunctional polyol. In some embodiments, polyol is a glycol (e.g., an oligomer with two alcohol end groups, a polymer with two alcohol end groups). Typically, a stoichiometric excess of at least one diisocyanate compound is used to react, thereby contributing to the formation of isocyanate-terminated polyurethane. In some embodiments, the ratio of at least one diisocyanate compound to glycol is from about 2:1 to about 1:2, or from about 1.5:1 to about 1:1.5, or from about 1:1. When using a polyol comprising more than two reactive -OH groups, one of ordinary skill in the art can adjust the ratio. More than one type of diisocyanate compound can be used, such as two types, three types, or four types of diisocyanate compounds. In addition, more than one type of glycol (or polyol) can be used, such as two types, three types, or four types of glycol. In some embodiments, three types of glycol are used.

The term diisocyanate has its ordinary meaning in the art and is used to describe linear, cyclic or branched hydrocarbons having two free isocyanate groups, including aromatic, cycloaliphatic and aliphatic hydrocarbons. Non-limiting examples of diisocyanate compounds include 4,4-methylenebis(isocyanatocyclohexyl) (H12MDI), α,α,α,α-tetramethylxylene diisocyanate, 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane isophorone diisocyanate and its derivatives, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) and its derivatives, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate. , m-isopropenyl-α,α-dimethylbenzyl isocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, 1,5-naphthalene diisocyanate, phenylene diisocyanate, trans-cyclohexane-1,4-diisocyanate, dimethylphenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, di- and tetraalkyldiphenylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isomers of tolylene diisocyanate, 1-methyl-2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, 1-isocyanatomethyl-3-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane, chlorinated and brominated diisocyanates, phosphorus-containing diisocyanates, 4,4′-diisocyanatophenylperfluoroethane, tetramethoxy Butane-1,4-diisocyanate, butane-1,4-diisocyanate, hexane-1,6-diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate, ethylene diisocyanate, phthalic acid-bis-isocyanatoethyl ester, and polyisocyanates containing reactive halogen atoms, such as 1-chloromethylphenyl-2,4-diisocyanate, 1-bromomethylphenyl-2,6-diisocyanate, 3,3-bis-chloromethylether-4,4′-diphenyl diisocyanate. In some embodiments, the diisocyanate compound is 4,4-methylenebis(cyclohexylisocyanate).

Although most of the embodiments described herein use a second reagent comprising a polyol or diol, this is by no means restrictive, and other types of second reagents can be used to form adhesives (e.g., adhesives comprising polyurethanes). In some embodiments, the second reagent comprises a polyamine or a diamine. In certain embodiments, the second reagent comprises a sulfhydryl group. Those skilled in the art can select a suitable second reagent based on the teachings of this specification. The term polyol has its general meaning in the art and refers to any organic compound with two or more hydroxyl groups, wherein the hydroxyl group can react with an isocyanate group. Typically, in order to form linear polyurethanes, the polyol used is a diol. In some embodiments, the diol is a difunctional polyol. In certain embodiments, the diol is a difunctional oligomer with two reactive alcohol groups. Non-limiting examples of difunctional polyols include polyethylene glycol, polypropylene glycol (PPO), and polytetramethylene glycol. The molecular weight of the polyol can be different. In some embodiments, the molecular weight (Mn) is less than about 5000, or less than about 3000, or from about 500 to about 5000, or from about 500 to about 4000, or from about 500 to about 3000.

In some embodiments, at least one glycol comprises ionic group (such as carboxylic acid group).Ionic group can be used for stabilizing polyurethane (such as when being dispersed in water) and/or can be used for crosslinking.The limiting examples of the glycol comprising ionic group comprises dimethylol propionic acid (DMPA), dimethylol butyric acid, dimethylol valeric acid, dihydroxyethyl propionic acid, dihydroxyethyl butyric acid, 1,4-dihydroxy-2-butanesulfonic acid, 1,5-dihydroxy-2-pentanesulfonic acid, 1,5-dihydroxy-3-pentanesulfonic acid, 1,3-dihydroxy-2-propanesulfonic acid, dimethylolethanesulfonic acid, N-methyldiethanolamine, N-ethyldiethanolamine, N-propyldiethanolamine, N,N-dimethyl-2-dimethylolbutylamine, N,N-diethyl-2-dimethylolbutylamine, N,N-dimethyl-2-dimethylolpropylamine.In some embodiments, ionic group is carboxylic acid group. Non-limiting examples of diols containing carboxylic acid groups include dimethylol propionic acid, dimethylol butyric acid, dimethylol valeric acid, dihydroxyethyl propionic acid, and dihydroxyethyl butyric acid, polyester diols, and other polymeric carboxylic acid groups. In some embodiments, the diol containing ionic groups is dimethylol propionic acid.

As described above, in some embodiments, the second agent can include a first type of second agent (e.g., a first type of diol) and a second type of second agent (e.g., a second type of diol). In some embodiments, the second agent can include a first type of second agent (e.g., a first type of diol), a second type of second agent (e.g., a second type of diol), and a third type of second agent (e.g., a third type of diol). In some embodiments, the first type of diol is a difunctional polyol (e.g., polypropylene glycol), the second type of diol contains an ionic group (e.g., a carboxylic acid group, such as DMPA), and the third type of diol can serve as a nonionic stabilizer.

As mentioned above, although polyurethane is provided as exemplary adhesive material, those skilled in the art can use compositions and methods as herein described in the adhesive that comprises other types of adhesive.In some embodiments, adhesive comprises acrylic acid.In certain embodiments, adhesive comprises two or more types of adhesive (for example polyurethane and acrylic acid).

Such adhesive mixture (i.e., hybrid adhesive) can be formed by physically blending at least two components, and the at least two components can be any combination of solution or dispersed materials in aqueous or solvent-based media. In some embodiments, hybrid adhesive can also be formed by synthetic polymerization method, wherein a component is polymerized under the existence of a second polymeric component, or two polymers can be formed simultaneously. In some cases, hybrid adhesive can be formed by emulsifying polymerizable monomers in the adhesive dispersion directly for coating method, and/or formed by a solution of reactive monomers in adhesive dispersion or solution. In some cases, the polymerization of monomers can occur in the first or second stage (i.e., solidification), and can also contribute to ink surface void filling and particle aggregation (such as if using dispersion).

As described above, in some embodiments, the binder material comprises two or more reactive functional groups.The reactive functional groups may be arranged as terminal groups along the backbone, or along chains extending from the backbone.

Reactive functional group generally refers to the chemical group (present on adhesive) designed to react with one or more curing materials (such as cross-linking agent, chain extension agent).In some embodiments, reactive functional group and curing material reaction form curing part, such as cross-linking, thermoplastic bonding, the key between two types of adhesive materials etc.In certain embodiments, reactive functional group can react with curing material such as cross-linking agent to form crosslinking.In some cases, reactive functional group can be designed to react with another reactive functional group under one group of specific conditions (such as in a specific temperature range).In some embodiments, reactive functional group can react under certain conditions that make adhesive material experience thermoplastic drying.The limiting examples of reactive functional group include hydroxyl, carbonyl, aldehyde, carboxylate, amino, imino, imide, azido, ether, ester, sulfhydryl (thiol), silanyl, nitrile, carbamate, imidazole, pyrrolidone, carbonate, acrylate, alkenyl and alkynyl. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps. The invention relates to a method for preparing a double-curing adhesive having a plurality of curing steps.

In some embodiments, the reactive functional groups are present on the adhesive backbone. For example, in embodiments where the adhesive comprises a polyurethane, the reactive functional groups may be present on diisocyanate groups and/or polyol groups that react to form the polyurethane.

In certain embodiments, the reactive functional group is present on the end-blocking agent.As described above for exemplary isocyanate-terminated polyurethane adhesive, isocyanate-terminated polyurethane can be blocked by reacting the end-blocking agent with at least one type, thereby forming an end-blocked adhesive (for example, an end-blocked polyurethane).As mentioned above, the use of end-blocking agents can contribute to the molecular weight of the control adhesive.In some embodiments, the end-blocking agent more than one type, for example, two types, three types or four types of end-blocking agents can be used.The end-blocking agent total amount can be adjusted to prepare a partially or completely blocked adhesive.

For example, partial end-blocking can be achieved by reacting an adhesive (e.g., isocyanate-terminated polyurethane) with a stoichiometric amount of an end-blocking agent (multiple end-blocking agents) less than 100%. In some embodiments, after the isocyanate-terminated polyurethane reacts with the end-blocking agent, 50 to 100% of the polyurethane is end-blocked. In certain embodiments, after the isocyanate-terminated polyurethane reacts with the end-blocking agent, at least about 50%, at least about 60%, at least about 75%, at least about 80%, or at least about 90% of the polyurethane is end-blocked with an end-blocking group. In some cases, less than or equal to 100%, less than or equal to about 90%, less than or equal to about 80%, less than or equal to about 75%, or less than or equal to about 60% of the polyurethane is end-blocked with an end-blocking group. Combinations of the above ranges are also possible (e.g., about 50% to 100%, 50% to 75%, 60% to 90%, 75% to 100%). Those skilled in the art will be aware of methods for determining the residual amount of isocyanate groups, for example by determining isocyanate loss by IR and isocyanate titration and/or by gas chromatography-mass spectrometry of residual terminal monomers. Blocked adhesives such as polyurethanes may be neutralized and/or chain extended as described in more detail herein.

In certain embodiments, the capping agent comprises a reactive functional group. Non-limiting examples of suitable capping agents (eg, comprising a reactive functional group) are shown in FIG2 and described in more detail below.

In some embodiments, at least one type of capping agent comprises a compound having a structure as shown in Formula (I):

Wherein R ¹ is selected from hydrogen, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted nitrile group, optionally substituted carbamate group, optionally substituted imidazolium group, optionally substituted pyrrolidone group, optionally substituted carbonate group, optionally substituted acrylate group, optionally substituted ether group, optionally substituted ester group, optionally substituted halide group, optionally substituted acid group, optionally substituted silane group, optionally substituted thiol group, L is a linking group, optionally absent, and represents the position of the bond connected to the polyurethane. The non-limiting examples of linking groups include optionally substituted alkylene, optionally substituted heteroalkylene, optionally substituted arylene and optionally substituted heteroarylene. In some embodiments, R ¹ is hydrogen. In certain embodiments, R ¹ comprises reactive functional groups. In some embodiments, L comprises reactive functional groups.

In some embodiments, a blocking agent comprising formula (I) is incorporated into the polyurethane by reacting an isocyanate-terminated polyurethane with a blocking agent comprising formula (II):

QLR ¹ (II),

wherein L and R ¹ are as described above for formula (I). In some embodiments, Q is hydroxyl (HO-) or amino (H ₂ N-). For example, in some such embodiments, the capping agent is n-butanol.

Furthermore, while polyurethane is used herein as an exemplary binder, one skilled in the art will be able to use any suitable binder having one or more suitable capping agents, as described herein.

In some embodiments, at least one type of end-capping agent comprises a nitrile, resulting in an end-capped polyurethane comprising a nitrile. The term "nitrile" has its ordinary meaning in the art and generally refers to a molecular group comprising at least one type of cyanide group. In some embodiments, the end-capping agent comprising a nitrile comprises formula (III):

wherein L is as described above in formula (I).

In some embodiments, Formula (III) comprises Formula (IV):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (III) or (IV) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (V):

Q-L-C≡N (V)

wherein Q is hydroxy or amino. For example, in some such embodiments, the capping agent is 3-hydroxypropionitrile.

In some embodiments, at least one type of capping agent comprises a carbamate, resulting in a capped polyurethane comprising a carbamate. The term "carbamate" has its ordinary meaning in the art and generally refers to a molecular group containing at least one type of _-OOCNH2 group. In some embodiments, the capping agent comprising a carbamate comprises formula (VI):

Wherein L is as described above in formula (I), and wherein each _R is identical or different and is selected from hydrogen, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted halide group and optionally substituted hydroxyl. In certain embodiments, ^R comprises reactive functional groups. In some embodiments, L comprises reactive functional groups.

In some embodiments, Formula (VI) comprises Formula (VII):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (VI) or (VII) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (VIII):

wherein Q is hydroxy or amino, L is as described above in formula (I), and R ² is as described above in formula (VI). For example, in some such embodiments, the capping agent is hydroxyethyl carbamate.

In some embodiments, at least one type of capping agent comprises imidazole, resulting in a capped polyurethane comprising imidazole. In some embodiments, the capping agent comprising imidazole comprises formula (IX):

wherein L is as described above in formula (I), and R ² is as described above in formula (VI).

In some embodiments, Formula (IX) comprises Formula (X):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (IX) or (X) is combined with the polyurethane by reacting an isocyanate-terminated polyurethane with a blocking agent comprising formula (XI):

wherein Q is hydroxy or amino, and R ² is as described above in formula (VI). For example, in some such embodiments, the capping agent is 2-hydroxyethylmethylimidazolium.

In some embodiments, at least one type of end-capping agent includes cyclic carbonate, producing an end-capped polyurethane comprising an end-capping agent comprising a cyclic carbonate. Term "cyclic carbonate" has its common meaning in this area, and refers to a molecular group containing at least one type of cyclic carbonate oligomer, such as a dimer, trimer, tetramer, etc. In some embodiments, the end-capping agent comprising a cyclic carbonate comprises formula (XII):

wherein ^R is as described above in formula (VI), L is as described above in formula (I), n is 1-4 and represents the position of the bond to the polyurethane. In some embodiments, ^R is hydrogen. In some embodiments, n is 1. In certain embodiments, n is 2. In some embodiments, L is an optionally substituted alkylene. In some embodiments, formula (XII) comprises formula (XIII):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, R ¹ is hydrogen. In some embodiments, the blocking agent comprising formula (II) or (III) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XIV):

wherein L and R ² are as described above for formula (XII), and Q is hydroxy or amino. In some embodiments, the compound of formula (XIV) comprises formula (XV):

wherein m is as described above for formula (XIII). In some embodiments, m is 1. For example, in some such embodiments, the capping agent is glycerol carbonate.

In some embodiments, the capping agent comprises pyrrolidone. In some embodiments, the capping agent comprising pyrrolidone comprises formula (XVI):

Wherein each R ² is identical or different, and is selected from hydrogen, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted halide group and optionally substituted hydroxyl, M is a linking group, optionally does not exist, and -- represents the position of the key being connected to polyurethane. The limiting examples of linking group includes optionally substituted alkylene and optionally substituted heteroalkylene. In some embodiments, each R ² is hydrogen. In some embodiments, M is optionally substituted alkylene. In some embodiments, formula (XVI) includes formula (XVII). In certain embodiments, M includes reactive functional groups.

wherein r is 1-10. In some embodiments, r is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, r is 2. In some embodiments, a blocking agent comprising formula (XVI) or (XVII) is combined with a polyurethane by reacting an isocyanate-terminated polyurethane with a blocking agent comprising formula (XVIII):

wherein M and R ² are as described above for formula (XVI), and Q is hydroxy or amino. In some embodiments, the compound of formula (XVIII) comprises formula (XIX):

wherein r is as described above for Formula (XVII). In some embodiments, r is 2. For example, in some such embodiments, the capping agent is 2-hydroxyethylpyrrolidone.

In some embodiments, at least one type of capping agent comprises an acrylate, resulting in a capped polyurethane comprising an acrylate. In some embodiments, the capping agent comprising an acrylate comprises formula (XX):

wherein L is as described above in formula (I), and R ² is as described above in formula (VI).

In some embodiments, Formula (XX) comprises Formula (XXI):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (XX) or (XXI) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XXII):

wherein Q is hydroxy or amino, and R ² is as described above in formula (VI). For example, in some such embodiments, the capping agent is 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.

In some embodiments, at least one type of capping agent comprises an ether, resulting in an ether-containing capped polyurethane. In some embodiments, the ether-containing capping agent comprises formula (XXIII):

wherein L is as described above in formula (I), and R ² is as described above in formula (VI).

In some embodiments, Formula (XXIII) comprises Formula (XXIV):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (XXIII) or (XXIV) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XXV):

wherein Q is hydroxy or amino, and R ² is as described above in Formula (VI). For example, in some such embodiments, the capping agent is 2-ethoxyethanol.

In some embodiments, at least one type of capping agent comprises a halide, resulting in a halide-containing capped polyurethane. In some embodiments, the halide-containing capping agent comprises formula (XXVI):

Wherein L is as described above in formula (I), X is halogen (e.g., F, Cl, Br, I), and Y is optionally substituted arylene, optionally substituted C _1-10 alkylene or optionally substituted epoxyalkylene. In some embodiments, Y comprises a reactive functional group. In certain embodiments, X comprises a reactive functional group.

In some embodiments, Formula (XXVI) comprises Formula (XXVII):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (XXVI) or (XXVII) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XXVIII):

wherein Q is hydroxy or amino. For example, in some such embodiments, the capping agent is 4-chlorobenzyl alcohol.

In some embodiments, Formula (XXVI) comprises Formula (XXVII):

wherein m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, m is 1. In some embodiments, the blocking agent comprising formula (XXVI) or (XXVII) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XXVIII):

wherein Q is hydroxy or amino. For example, in some such embodiments, the capping agent is 4-chlorobenzyl alcohol.

In some embodiments, at least one type of end-capping agent comprises an acid, resulting in an acid-containing end-capped polyurethane. In some embodiments, the end-capping agent comprising an acid comprises Formula (XXIX) or Formula (XXX):

wherein L is as described above in formula (I), and A is sulfur, phosphorus, or boron. In some such embodiments, L is -(CH ₂ ) _m - and m is 1-10. In some embodiments, m is 1-5, or 1-3, or 1, or 2, or 3, or 4, or 5. In some embodiments, the blocking agent comprising formula (XXIX) or (XXX) is combined with the polyurethane by reacting an isocyanate-terminated polyurethane with a blocking agent comprising formula (XXXI) or (XXXII):

wherein Q is hydroxy or amino. For example, in some such embodiments, the capping agent is 3-aminopropanesulfonic acid.

Additional suitable capping agents including ethers and/or acids are described, for example, in US Patent Application No. US 2011/0306724, which is incorporated herein by reference.

In some embodiments, at least one type of end-capping agent comprises a silane, resulting in an end-capped polyurethane comprising a silane. In some embodiments, the end-capping agent comprising a silane comprises formula (XXXIII):

wherein L is as described above in formula (I), and wherein each R ³ is the same or different and comprises -(CH ₂ ) _n - or -O-(CH ₂ ) _n , wherein each n is the same or different and is 1 to 4. In some embodiments, each n is the same or different and is 1 or 2. In some embodiments, R ³ comprises a reactive functional group.

In some embodiments, the blocking agent comprising formula (XXXIII) is combined with the polyurethane by reacting the isocyanate-terminated polyurethane with a blocking agent comprising formula (XXXIV):

wherein Q is hydroxy or amino. For example, in some such embodiments, the capping agent is 3-aminopropyltrimethoxysilane.

In some embodiments, the end-capping reagent of the first type and the second type is used. For example, in some cases, the end-capping reagent of the first type comprises cyclic carbonate, and the end-capping reagent of the second type comprises pyrrolidone. The ratio of the end-capping reagent of any suitable first type and the end-capping reagent of the second type can be used, for example, from about 1:2 to about 2:1, from about 1:1.5 to about 1.5:1 or about 1:1.

Those of ordinary skill in the art will know other suitable types of end-capping agents and/or agents other than those described herein. For example, in some embodiments, the end-capping group and/or end-capping agent comprises an alkyl group, an aryl group, a cyano group, a carbamate group, and/or an acrylate group.

In some embodiments, the adhesive (e.g., a blocked or isocyanate-terminated polyurethane) can be chain extended by reacting the adhesive with a chain extension agent. Chain extension can be performed under conditions suitable for obtaining a target Mn for the adhesive and/or obtaining a target functionality for the adhesive. In some embodiments, chain extension can be performed by reacting one or more pendant groups of the adhesive. In some embodiments, the reactive functional group is present on the chain extension agent.

Those of ordinary skill in the art will be aware of methods and systems for determining the molecular weight of polyurethanes or other polymers (e.g., polyols used to prepare polyurethanes). In some embodiments, molecular weight can be determined using gel permeation chromatography (GPC). In some embodiments, molecular weight (Mn) is determined using GPC calibrated with polystyrene standards.

One of ordinary skill in the art will be aware of methods and systems for determining functionality (i.e., the average number and/or proportion per molecule of reactive functional groups present in the adhesive that are capable of reacting with a curing species to form a cured moiety, such as a crosslink).

In addition, with reference to polyurethane as an exemplary adhesive, in some embodiments, the chain extender may comprise a diol or a diamine. For example, the chain extender may comprise a diamino compound. Non-limiting examples of diamino compounds include compounds having the structure H ₂ NR ⁴ -NH ₂ , wherein R ⁴ is an optionally substituted arylene group or an optionally substituted alkylene group. In some embodiments, R ⁴ is -(CH ₂ ) p -, wherein p is 1-10, or 2-8, or 3-7, or 4-6. In some embodiments, the chain extender is hexamethylenediamine. In certain embodiments, R ⁴ comprises a reactive functional group. In an exemplary embodiment, the chain extender is 1,3-diamino-2-propanol (e.g., wherein a hydroxyl group is a reactive functional group).

In some embodiments, the chain extension agent comprises a diol compound (e.g., as described above). Non-limiting examples of diol compounds include compounds having the structure HO- ^R5 -OH, wherein ^R5 is an optionally substituted arylene or an optionally substituted alkylene. In some embodiments, ^R5 is -(CH2)p-, wherein p is 1-10, or 2-8, or 3-7, or 4-6. In certain embodiments, ^R5 comprises a reactive functional group. In an exemplary embodiment, the chain extension agent comprises a structure such as Formula (XXXV):

wherein m is 1-100. In some embodiments, m is at least 1, at least 2, at least 5, at least 10, at least 20, at least 50, or at least 75. In certain embodiments, m is less than or equal to 100, less than or equal to 75, less than or equal to 50, less than or equal to 20, less than or equal to 10, less than or equal to 5, or less than or equal to 2. Combinations of the foregoing ranges are also possible (e.g., m is 1 to 100, m is 1 to 20, m is 10 to 50, m is 20 to 75, m is 50 to 100). Other ranges are also possible. Additional non-limiting examples of chain extension agents comprising one or more functional groups (e.g., diamines and diols) are shown in FIG3 .

In some embodiments, at least a portion of the reactive isocyanate groups remaining after polymerization can be deactivated by adding one or more terminating agents such that the residual isocyanate groups are substantially unreactive. For example, in some embodiments, the terminating agent can be a blocking agent to terminate further reaction of the isocyanate groups.

In certain embodiments, the acid groups present on the polyurethane can be dispersed in water and neutralized by adding one or more neutralizing agents. The non-limiting examples of neutralizing agents include hydroxides (such as potassium hydroxide, lithium hydroxide) and tertiary amines (such as triethylamine, tributylamine, ethyldipropylamine, ethyldibutylamine, diethylpropylamine, diethyl monobutylamine). In some embodiments, the neutralizing agent is triethylamine. Similarly, the bases present on the polyurethane can be dispersed in water and neutralized by adding one or more acidic neutralizing agents such as acetic acid. The usage amount of the neutralizing agent can be about 10-150% (for example, relative to the number of acid groups present on the polyurethane). As mentioned above, adhesive as described herein (for example, as an aqueous dispersion, in an adhesive layer) generally includes two or more curing portions formed by the reaction (i.e., curing) of one or more reactive functional groups (for example, with one or more curing substances). For example, in some embodiments, the adhesive is formed by the reaction of at least one reactive functional group, at least two reactive functional groups, at least three reactive functional groups, or at least four reactive functional groups. Each reactive functional group may be the same or different and is generally capable of reacting with one or more curing species, as described in more detail below.

In some embodiments, the reactive functional group has a specific dipole moment. In some cases, compared to traditional adhesives, the electro-optical performance of electro-optical displays can be improved by using an adhesive formed by the reaction of one or more functional groups with relatively high dipole moments (e.g., a dipole moment greater than 2 debyes). Those skilled in the art will be able to select a suitable method for measuring the dipole moment of the reactive group. The dipole moment of the functional group can be from about 2 debyes to about 6 debyes. In some embodiments, the dipole moment of the functional group is at least about 2 debyes, at least about 2.5 debyes, at least about 3 debyes, at least about 4 debyes, or at least about 5 debyes. For example, a cyclic carbonate group (e.g., comprising a structure such as formula (XIV)) can have a dipole moment of about 5 debyes, a pyrrolidone (e.g., comprising a structure such as formula (XVII)) can have a dipole moment of about 4 debyes, and a nitrile (e.g., comprising a structure such as formula (V)) can have a dipole moment of about 3.5 debyes.

The reactive functional group is present in the tackiness agent with the amount of about 5 % by mole (mol%) of relative total adhesive composition to about 25 % by mole usually.In some embodiments, the reactive functional group is present in the tackiness agent with at least about 5 % by mole, at least about 10 % by mole, at least about 15 % by mole or at least about 20 % by mole.In certain embodiments, the reactive functional group is present in the tackiness agent with the amount of less than or equal to about 25 % by mole, less than or equal to about 20 % by mole, less than or equal to about 15 % by mole or less than or equal to about 10 % by mole.The combination of above-mentioned scope also is possible (for example about 5 % by mole to about 25 % by mole).

In some embodiments, adhesive is solidified by the reaction (such as during adhesive curing) of at least one reactive functional group and at least one curing material.In exemplary embodiments, adhesive is solidified by the reaction (such as forming the first curing step of the first curing part) of the first reactive functional group and the first curing material, and the reaction (such as forming the second curing step of the second curing part) of the second reactive functional group and the second curing material. Those skilled in the art will appreciate that, based on the teaching of this specification, the reaction of at least one reactive functional group and at least one curing material is not intended to be included in the reaction (such as diisocyanate and the second reagent such as glycol forming polyurethane) of forming adhesive backbone before, for example, adding end-capping reagent and/or chain extension reagent. That is to say, the reaction of at least one reactive functional group as herein described and at least one curing material occurs generally during adhesive curing (such as making the mechanical properties (such as Young's modulus of elasticity increase) of adhesive, rheological properties (such as viscosity increase) etc. one kind change). However, as mentioned above, one or more reactive functional groups can be present in adhesive backbone, and can react with one or more curing materials.

In some embodiments, the adhesive is cured by reaction of a reactive functional group with a curing agent, such as a chain extender, a cross-linking agent, or a combination thereof. In certain embodiments, the adhesive is cured by reaction of a first reactive functional group with a curing agent, such as a second reactive functional group that may be present on the backbone or on a capping agent. In an exemplary embodiment, the adhesive may be cured by thermoplastic drying the adhesive material to react two or more reactive functional groups present on the adhesive material.

In some cases, as described above, the curing material comprises a type of reactive functional group. For example, the curing material may comprise a carboxylic acid group designed to react with the hydroxyl reactive functional group present on the main chain of the adhesive material or on the end-capping reagent. In an exemplary embodiment, the reactive functional group comprises a carbon-carbon double bond or a carbon-carbon triple bond, which reacts with the curing material such as a sulfhydryl group through a thiol-ene reaction. In some embodiments, the reactive functional group can react with a cross-linking agent (i.e., a cross-linking agent). That is, in some cases, the curing material comprises a cross-linking agent. Non-limiting examples of suitable cross-linking agents include monomers, oligomers, and polymers containing multifunctional reactive groups, and the multifunctional reactive groups include amine groups, carbodiimide groups, epoxy groups, alcohol groups, thiol groups, isocyanate groups, etc. Those skilled in the art will be able to select suitable cross-linking agents based on the teachings of this specification. In some embodiments, the curing material is a chain extension agent as described above. In certain embodiments, the reactive functional group can self-crosslink and/or self-extend, such as mono-, di-, or trialkoxysilanes. In some such embodiments, the curing species may comprise the same type of group as the reactive functional group (eg, a silane group) that is capable of reacting with the reactive functional group.

In some embodiments, adhesive is formed by reacting one or more reactive functional groups present on adhesive (such as polyurethane) with two or more cross-linking agents. For example, in certain embodiments, adhesive is reacted with the first cross-linking agent (i.e., the first solidification) and the second cross-linking agent (i.e., the second solidification). In some embodiments, during the first curing step, such as during the drying and/or lamination of adhesive, the adhesive backbone is reacted with the first cross-linking agent. In certain embodiments, adhesive is subsequently reacted with the second cross-linking agent during the second curing step. In some embodiments, the first cross-linking agent and the second cross-linking agent have different rates of cross-linking with adhesive (such as with one or more reactive functional groups on the adhesive backbone). In certain embodiments, the first cross-linking agent and the second cross-linking agent have similar rates of cross-linking with the reactive functional groups present on adhesive. Advantageously, using two or more cross-linking agents provides desired rheological properties that can realize the effective flattening of adhesive during the lamination and/or drying of adhesive, and/or low adhesive layer coating weight. In some embodiments, the mechanical properties of adhesive can be controlled by the second cross-linking agent (i.e., during the second curing step). In some embodiments, the long-term stress reliability of adhesive can be controlled by the second cross-linking agent.

In some embodiments, the functional reactive groups react with the curing material in the presence of a stimulus such as electromagnetic radiation (e.g., visible light, UV light, etc.), an electron beam, elevated temperature (e.g., used during solvent extraction or condensation reactions), a compound (e.g., thiol-ene), and/or a crosslinking agent. Exemplary embodiments of the types of reactive functional group reactions (e.g., curing steps) are shown in FIG4 , and include diamine or polyamine crosslinking, self-crosslinking, thiol-ene/UV crosslinking, and UV crosslinking.

Although the above description relates to exemplary polyurethane adhesive compositions, those skilled in the art will appreciate that reactive functional groups can be introduced into other types of adhesive materials. For example, epoxy functional groups can be introduced into polyacrylate-based adhesives using epoxy-containing acrylate monomers, double bond functional groups can be introduced into alkyd-based materials, etc. In some embodiments, as described above, the adhesive can comprise two or more types of adhesive materials (i.e., adhesive mixtures). For example, in some cases, the adhesive can comprise polyacrylates, such as acrylic acid (e.g., designed to undergo a first cure by thermoplastic drying) and polyurethanes (e.g., designed to undergo a second cure by reacting the reactive functional groups present on the polyurethane and acrylates).

As mentioned above, in some embodiments, the adhesive layer is located between the front plate electrode and the back plate electrode, and it can apply the electric field required to change the electrical state of the electro-optical material. That is to say, the electrical properties (such as resistivity, conductivity) of the adhesive can change the electric field applied to the electro-optical material. If the resistivity of the adhesive is too high, then a significant drop in voltage may occur in the adhesive layer, and the voltage across the electrodes needs to be raised. Raising the voltage across the electrodes in this way is undesirable because it may increase the power consumption of the display, and it may be necessary to use a more complex and expensive control circuit to process the voltage involved in the rise. On the contrary, if the adhesive layer that can extend continuously across the electro-optical component contacts the electrode matrix, as in an active matrix display, the volume resistivity of the adhesive should not be too low, otherwise the lateral current conduction by the continuous adhesive layer may cause undesirable crosstalk between adjacent electrodes. In addition, since the volume resistivity of most materials may decrease rapidly with increasing temperature, if the volume resistivity of the adhesive is too low, the performance of the assembly at a temperature significantly higher than room temperature may be adversely affected. Thus, in some embodiments, the adhesive may have a volume resistivity in a range of about 108 ohm·cm to about 1012 ohm·cm, or about 109 ohm·cm to about 1011 ohm·cm (e.g., at a component operating temperature of about 20° C.). Other ranges of volume resistivity are also possible.

The adhesive layer after curing (e.g., after the first and second curing) can have a specific average coating weight. For example, the average coating weight of the adhesive layer can be from about 2 g/m ² to about 25 g/m ^2. In some embodiments, the average coating weight of the adhesive layer is at least about 2 g/m ² , at least about 4 g/m ² , at least about 5 g/m ² , at least about 8 g/m ² , at least about 10 g/m ² , at least about 15 g/m ² , or at least about 20 g/m ^2. In certain embodiments, the average coating weight of the adhesive layer is less than or equal to about 25 g/m ² , less than or equal to about 20 g/m ² , less than or equal to about 15 g/m ² , less than or equal to about 10 g/m ² , less than or equal to about 8 g/m ² , less than or equal to about 5 g/m ² , or less than or equal to about 4 g/m ² . Combinations of the above-referenced ranges are also possible (e.g., about 2 g/ ^m2 to about 25 g/ ^m2 , about 4 g/ ^m2 to about 10 g/ ^m2 , about 5 g/ ^m2 to about 20 g/ ^m2 , about 8 g/ ^m2 to about 25 g/ ^m2 ). Other ranges are also possible.

Adhesive layer can have specific average wet coating thickness (for example, making adhesive not significantly change the electricity and/or light property of electro-optical assembly) before solidification.For example, the average wet coating thickness of adhesive layer can be approximately 1 micron to approximately 100 microns, approximately 1 micron to approximately 50 microns or approximately 5 microns to approximately 25 microns.In some embodiments, the average wet coating thickness of adhesive layer can be less than approximately 25 microns, less than approximately 20 microns, less than approximately 15 microns, less than approximately 12 microns, less than approximately 10 microns or less than approximately 5 microns.In some embodiments (for example, adhesive is directly wet-coated in the embodiment of electro-optical material), the average wet coating thickness of adhesive layer can be approximately 1 micron to approximately 50 microns or approximately 5 microns to approximately 25 microns or approximately 5 microns to approximately 15 microns.In some embodiments (for example, adhesive is coated on the layer, then laminated to the embodiment of electro-optical material), the average wet coating thickness of adhesive layer can be approximately 15 microns to 30 microns or 20 microns to 25 microns.Other wet coating thickness is also possible.

It should be understood that the adhesive layer may cover the entire underlying layer, or the adhesive layer may cover only portions of the underlying layer.

In addition, adhesive layer can be applied as laminate, and it produces thicker adhesive layer usually, or it can be applied as outer coating, and it produces thinner layer than laminate usually.Outer coating can use dual curing system, wherein before outer coating, carries out first solidification, makes adhesive can be coated on electro-optical material surface (or another surface), and second solidifies and fixes material after outer coating.If lower surface is rough and only applies thin layer, then outer coating can be rough, or outer coating can be used to make rough lower surface planarization.Smoothing can occur in single step, wherein applies outer coating so that rough surface planarization, for example, adds enough adhesives to fill any pores, and makes surface smooth and increases total thickness with minimum limit.Alternatively, planarization can occur in two steps, wherein applies outer coating and with minimum limit coating rough surface, and applies second coating with planarization.In another scheme that selects, outer coating can be applied to smooth surface.

1C and 1D , in some embodiments, the electro-optical assembly includes an electro-optical material layer 125, a capsule 150, and a binder 160. In some embodiments, the binder can also be an adhesive as described above. For example, the binder can be a polyurethane (e.g., comprising at least one type of end group).

The electro-optical assembly of the present invention may constitute a complete electro-optical display, or may constitute only a subassembly of such a display (e.g., an electrophoretic display). Representative electrophoretic displays have been described, for example, in U.S. Patent No. 7,012,735, granted on March 14, 2006, the entire contents of which are incorporated herein by reference. A complete electro-optical display typically includes at least one, and typically two, electrodes present to generate the electric field necessary to change the optical state of the electro-optical material, although in some cases, only one of the two electrodes may be a permanent part of the display, and the other electrode is in the form of a movable stylus or similar instrument that can be moved across the display to write on the display. For example, in some embodiments, the front plate electrode 130 comprises an electrode. In certain embodiments, the back plate electrode 110 comprises an electrode. In some cases, the electrode may be light-transmissive. For example, the assembly may have the form of an active matrix display, the first layer of which comprises a single continuous light-transmissive electrode that extends across a plurality of pixels, typically all pixels, of the display.

In some embodiments, the front-plate electrode 130 and/or the back-plate electrode 110 comprise one or more electrode layers that are patterned to define pixels of the display. For example, one electrode layer may be patterned into elongated row electrodes, and a second electrode layer may be patterned into elongated column electrodes extending at right angles to the row electrodes, with pixels being defined by the intersections of the row and column electrodes. Alternatively, in some embodiments, one electrode layer has the form of a single continuous electrode, and the second electrode layer is patterned into a matrix of pixel electrodes, each of which defines one pixel of the display. In another type of electro-optic display intended for use with a stylus, print head, or similar movable electrode that is separate from the display, only one of the layers adjacent the electro-optic layer comprises an electrode, and the layer on the opposite side of the electro-optic layer is typically a protective layer intended to prevent the movable electrode from damaging the electro-optic layer.

1A-D , the front-plate electrode 130 may comprise a polymer film or similar support layer (e.g., which may support a relatively thin, light-transmitting electrode and protect the relatively fragile electrode from mechanical damage), and the back-plate electrode 110 may comprise a support portion and a plurality of pixel electrodes (e.g., which define a single pixel of a display). In some cases, the back-plate electrode may further comprise a nonlinear device (e.g., a thin-film transistor) and/or other circuitry for generating the electrical potential on the pixel electrodes required to drive the display (e.g., to switch each pixel to the optical state necessary to provide a desired image on the display).

The electro-optical assembly can be in the form of a front plate laminate. In such a front plate laminate, the front plate can include a light-transmitting conductive layer intended to form the front electrode of the final display. The front plate can include a polymer film or similar support layer (e.g., it supports the relatively thin conductive layer and protects it from mechanical damage). In some such embodiments, the electro-optical assembly can include a release sheet that is removed before laminating the front plate laminate to the backplane electrode to form the final display.

In some embodiments, the electro-optic material layer comprises an encapsulated electrophoretic medium. Referring again to Figures 1C and 1D, in some embodiments, the electro-optic material layer 125 comprises a capsule 150 and a binder 160, wherein the capsule 150 comprises the encapsulated electrophoretic medium. In some cases, the capsule can comprise an encapsulated electrophoretic medium, wherein the encapsulated electrophoretic medium comprises a plurality of small capsules, each of which itself comprises an internal phase containing electrophoretically mobile particles (e.g., ink particles) suspended in a liquid suspending medium and a capsule wall surrounding the internal phase. In some such embodiments, the capsule is held within a polymer binder (e.g., binder 160) to form a bonding layer located between two electrodes (e.g., in a front plate electrode and a back plate electrode). In some cases, the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium may be replaced by a continuous phase, thereby producing a so-called polymer-dispersed electrophoretic display, wherein the electrophoretic medium comprises a plurality of discrete electrophoretic fluid droplets and a continuous phase of polymer material, and the discrete electrophoretic fluid droplets within the polymer-dispersed electrophoretic display may be considered to be capsules or microcapsules even though there is no discrete capsule membrane associated with each individual droplet.

In some embodiments, the electrophoretic medium comprises a plurality of capsules, each capsule comprising a capsule wall, a suspending fluid encapsulated within the capsule wall, and a plurality of charged particles suspended in the suspending fluid and capable of moving therethrough upon application of an electric field to the medium, the medium further comprising a binder surrounding the capsules.

Encapsulated electrophoretic displays generally do not suffer from the problems of aggregation and deposition failure modes of conventional electrophoretic devices and offer additional advantages, such as the ability to print or coat the display on a variety of flexible and rigid substrates. The use of the term "printing" is intended to include all forms of printing and coating, including but not limited to: pre-metered coating, such as small piece die coating, slot or extrusion coating, slope or step flow coating, curtain coating; roll coating, such as roller-on-blade coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; screen printing process; electrostatic printing process; thermal printing process; inkjet printing process; electrophoretic deposition; and other similar techniques. Therefore, in some cases, the resulting display can be flexible. Moreover, because the display medium can be printed (e.g., using various methods), the display itself can be manufactured in an inexpensive manner.

In some embodiments, the electro-optic display is a “microdomain electrophoretic display.” In a microdomain electrophoretic display, charged particles and fluids are not encapsulated within microcapsules, but may be retained within a plurality of cavities formed within a carrier medium (eg, a polymer film).

While electrophoretic media are often opaque (e.g., in many types of electrophoretic media, the particles substantially block visible light from passing through the display) and operate in a reflective mode, many electrophoretic displays can be made to operate in a so-called "shutter mode," in which one display state is substantially opaque and the other is light-transmissive.

The above-mentioned adhesive can also be used for other electro-optic materials and electro-optic displays known in the art. For example, in some embodiments, the electro-optic material is solid (e.g., solid electro-optic display). In some such embodiments, the electro-optic material can include an internal liquid-filled or gas-filled space. Therefore, the term "solid electro-optic display" includes encapsulated electrophoretic displays, encapsulated liquid crystal displays, and other types of displays.

In some embodiments, electro-optical display is a rotating two-color component (e.g., rotating two-color ball) display. In some such embodiments, the display uses a large amount of corpuscles (typically spherical or cylindrical) that have two or more parts with different optical characteristics and internal dipoles. These corpuscles can be suspended in a liquid-filled vacuole within the matrix, which is filled with liquid so that the corpuscle is free to rotate. By applying an electric field to the display, the corpuscle is thus rotated to various positions and changes those that are seen by the viewing surface in the part of the corpuscle, the outward appearance of the display can be changed. This type of electro-optical medium is typically bistable.

The term "bistable" is used herein in its conventional sense in the art to refer to a display comprising display elements having first and second display states that differ in at least one optical property, such that after any given element is driven to assume its first or second display state by an addressing pulse of finite duration, that state persists after termination of the addressing pulse for at least several times, for example, at least four times, the minimum addressing pulse duration required to change the state of the display element. In some cases, some particle-based electrophoretic displays capable of displaying grayscale are stable not only in their extreme black and white states, but also in their intermediate gray states. Although, for convenience, the term "bistable" may be used herein to cover both bistable and multistable displays, such displays are generally referred to as "multistable" rather than "bistable."

Other electro-optic displays are known in the art and include those using electrochromic media, such as those in the form of nanochromic films comprising electrodes formed at least in part from a semiconducting metal oxide and a plurality of dye molecules attached to the electrodes that are capable of reversibly changing color; electrowetting displays; and particle-based electrophoretic displays in which a plurality of charged particles move through a suspending fluid under the influence of an electric field.

Adhesive layer can be formed using suitable technology known in the art. In some embodiments, adhesive layer is formed into film, then for example is applied to assembly by lamination. In such embodiment, adhesive (for example comprising end-blocking polyurethane as described herein) can be coated on peeling layer or other substrate (for example front or back plate electrode), and use technology known in the art to dry (for example by heating and/or being exposed to vacuum). Substrate can be included in indium tin oxide (ITO) or similar conductive coating (for example it serves as the electrode layer of final display) on plastic film or peeling layer (for example comprising flexible polymer). As specific non-limiting example, adhesive material can be distributed (for example by using mold or slit coater) on substrate. Material thickness can be controlled by the amount of material pumped by fluidity or per square area. Can prepare respectively containing pixel electrode array and suitable conductor arrangement to connect pixel electrode to drive circuit back plate electrode. In order to form final display, adhesive can be used to have substrate lamination (for example by applying heat and using roller laminator) with capsule/binder layer on it to back plate electrode.

In alternative embodiments, a similar method can be used to prepare an electrophoretic display for use with a stylus or similar movable electrode by replacing the backplane electrode with a simple protective layer, such as a plastic film, over which the stylus or other movable electrode can slide. In some such embodiments, the backplane electrode itself is flexible and is prepared by printing the pixel electrodes and conductors onto a plastic film or other flexible substrate.

Those of ordinary skill in the art will know the suitable conditions for synthetic methods described herein.For example, binder materials (such as isocyanate-terminated polyurethanes) can be prepared in a reactor wherein reactants (such as, diisocyanate compounds and second reagents such as diols) are combined, mixed and reacted, wherein heat can be transferred to or transferred out of the reactor. The synthesis of binder can be carried out in an inert atmosphere (such as in the absence of water, and in the presence of an inert gas such as nitrogen and/or argon). Reactants can be added in any particular order. Adhesive can be reacted with one or more other reagents (such as end-capping reagents (multiple end-capping reagents), chain extension reagents (multiple chain extension reagents), neutralizing reagents (multiple neutralizing reagents)). In some cases, after a suitable time period, a dispersion medium such as water is added to the reaction mixture. After synthesizing the binder material, the binder material can be dispersed in water (such as by adding water to the reaction mixture, or the reaction mixture is added to water). In some embodiments, the binder (such as end-blocked and/or neutralized) can be chain extended after being dispersed in water.

Adhesive material as described herein can be cured.Solidification can include but is not limited to the reaction (such as making adhesive crosslinked, extending, entangled etc.) of one or more reactive functional groups and one or more curing substances, as described herein.In some cases, adhesive can go through two or more curing steps (such as first curing and second curing).That is to say, adhesive can be cured (i.e. first curing) by making the first reactive functional group and the first curing substance react, and further cured (i.e. second curing) by making the second reactive functional group and the second curing substance react.In some embodiments, adhesive layer is formed by following: curing adhesive, so that the first reactive functional group and the first curing substance react, curing adhesive subsequently, so that the second reactive functional group and the second curing substance react.The first and second curing can occur substantially simultaneously, or occur at substantially different times.The first reactive functional group can be identical or different with the second reactive functional group.The first curing substance can be identical or different with the second curing substance.

Adhesive can be given the desired property of adhesive by using twice or more solidification (i.e. curing step).For example, the adhesive cured twice or more can have low coating weight and/or thickness compared with other adhesives, can give the rheological properties (such as after the first solidification and/or after the second solidification) of adhesive expectation, and/or can reduce or prevent space and/or defect from forming, make after the first solidification or the second solidification, in the adhesive layer, there is basically no space and/or defect. Adhesive should have enough bond strengths usually, so that desired layer (multilayer) is adhered to each other. In some cases, adhesive has enough bond strengths, so that after solidification (such as after the first solidification, after the second solidification) desired layer (multilayer) is adhered to each other. In some embodiments, electro-optical assembly is flexible, so adhesive can have enough flexibility, so that when assembly is flexed, defect can not be introduced into assembly.

Those skilled in the art will be able to select an appropriate method for measuring defects in adhesives, such as an Orange Peel test. For example, orange peel can be determined by using a wave scanning instrument to illuminate the sample at a 60° angle to the surface and measuring the intensity of the reflected light collected from an equal but opposite angle to the sample surface.

The adhesive may have a specific average crossover temperature (Tc, e.g., the temperature measured at tan δ = 1.0 at 1 Hz) before or after curing. For example, in some embodiments, the average crossover temperature of the adhesive before the first cure and/or before the second cure is from about 0°C to about 80°C. In certain embodiments, the average crossover temperature of the adhesive before the first cure and/or before the second cure is less than about 80°C, less than about 60°C, less than about 40°C, less than about 20°C, or less than about 10°C. After the first cure (before the second cure), the average crossover temperature may increase, but still be between about 0°C and about 80°C (e.g., between about 20°C and about 80°C). Adhesives having an average crossover temperature as described above can flow and be easily laminated to one or more layers (e.g., electrode layers, peel layers), and have significantly fewer defects than adhesives having higher crossover temperatures. It will be understood by those skilled in the art that curing (e.g., crosslinking) an adhesive will generally increase the crossover temperature, and, for example, the second cure may increase the crossover temperature to above 80°C. For example, in some embodiments, the average crossover temperature of the adhesive after the second cure may be from about 80°C to about 250°C. In certain embodiments, the average crossover temperature of the adhesive after the second cure is at least about 80° C., at least about 100° C., at least about 150° C., or at least about 200° C. In some cases, the average crossover temperature of the adhesive after the second cure is less than or equal to about 250° C., less than or equal to about 200° C., less than or equal to about 150° C., or less than or equal to about 100° C. Combinations of the above-referenced ranges are also possible.

The adhesive material can be distributed on the electrophoretic layer or on the peeling layer (e.g., by a die or slot coater). In other embodiments, the adhesive can be directly applied (e.g., by solution technology) to the electro-optical material (or other lower layer). The adhesive can then be dried using techniques known in the art (e.g., by heating and/or exposure to vacuum). Additional layers can then be applied to the outer surface of the adhesive.

As a specific example, a dispersion (e.g., polyurethane dispersed in water) comprising an adhesive material is dispensed onto the electro-optical material layer (e.g., by a die or slot coater). The thickness of the liquid material can be controlled, for example, by using a scraper. In some embodiments, the upper surface of the electro-optical material to which the adhesive is applied can be uneven. In such an embodiment, an adhesive can be applied so that the final outer surface of the adhesive is flat or substantially flat.

In an exemplary embodiment, an adhesive material (e.g., comprising a first type of reactive functional group and a second type of reactive functional group) can be coated on at least a portion of a first layer (e.g., indium tin oxide (ITO) or a similar conductive coating on a plastic film, a peeling layer, an electro-optical material layer) and cured (i.e., a first cure) so that the first type of reactive functional group reacts with the first type of curing substance (e.g., forming a first cured portion). In some such embodiments, the adhesive can be brought into contact with a second layer (e.g., indium tin oxide (ITO) or a similar conductive coating on a plastic film, a peeling layer, an electro-optical material layer) and cured (i.e., a second cure) so that the second type of reactive functional group reacts with the second type of curing substance (e.g., forming a second cured portion). It will be understood by those skilled in the art that curing the adhesive (e.g., first cure, second cure) typically causes the adhesive layer to adhere to one or more layers. For example, the adhesive may adhere to only one layer. In some cases, the adhesive adheres two layers together. In some cases, one or more layers (e.g., a peeling layer) may be removed prior to the second cure, and a third layer (e.g., indium tin oxide (ITO) or a similar conductive coating on a plastic film, peeling layer, electro-optical material layer) may be brought into contact with the adhesive (i.e., replacing the removed layer). In some such embodiments, the removed layer may be advantageous in reducing the roughness of the adhesive and/or protecting the adhesive layer (e.g., from physical damage, from contamination) prior to the second cure. One or more additional cures (third cure, fourth cure) may also be used. For example, in some cases, the adhesive comprises three or more reactive functional groups that may be cured over three or more curing steps.

Adhesive films can be formed on any substrate using techniques known in the art. For example, in some embodiments, an adhesive (e.g., polyurethane) is dispersed in water (or another solvent) and coated on a layer (e.g., indium tin oxide (ITO) or similar conductive coating on a plastic film, a peeling layer, an electro-optical material layer). Those of ordinary skill in the art will know the technology of forming a solution coating on the surface, such as spin coating, spray coating, printing, mold or slit coater, etc. Other additives may be present in the solution. The solution coating can then be dried using techniques known in the art (e.g., heat and/or vacuum) to form a film.

The methods described herein can be carried out at any suitable temperature. In some cases, each reaction (e.g., each curing stage) is carried out at about room temperature (e.g., about 25°C, about 20°C, about 20°C to about 25°C, etc.). However, in some cases, each reaction is carried out at a temperature lower than or higher than room temperature. In some embodiments, each reaction is carried out at a temperature of about 25°C to about 140°C, about 25°C to about 75°C, or about 50°C to about 100°C.

In some embodiments, one or more reactions can be carried out in the presence of a solvent. Alternatively, the reaction can be carried out under pure conditions. Non-limiting examples of solvents include hydrocarbons (e.g., pentane, hexane, heptane), halogenated hydrocarbons (e.g., chloroform, dichloromethane), ethers (e.g., diethyl ether, tetrahydrofuran (THF), 2-methoxyethyl ether (diethylene glycol dimethyl ether), and aromatic compounds (e.g., benzene, toluene). As described herein, in some embodiments, the reaction can also be carried out in water.

For convenience, specific terms used in this specification, examples, and appended claims are listed herein. Definitions of specific functional groups and chemical terms are detailed below. For purposes of the present invention, chemical elements are identified according to the CAS version of the Periodic Table of the Elements, which appears on the inside cover of the Handbook of Chemistry and Physics, 75th edition, and specific functional groups are generally defined as described therein. In addition, the general principles of organic chemistry, as well as specific functional group moieties and reactivities, are described in Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito: 1999.

As used herein, the term "aliphatic" includes saturated and unsaturated non-aromatic straight chain (i.e., non-branched), branched, acyclic and cyclic (i.e., carbocyclic) hydrocarbons, which are optionally substituted with one or more functional groups. As will be understood by those skilled in the art, "aliphatic" is intended to include, but is not limited to, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl and cycloalkynyl moieties in this article. Therefore, as used herein, the term "alkyl" includes straight chain, branched and cyclic alkyl. Similar conventions apply to other general terms, such as "alkenyl", "alkynyl" etc. In addition, as used herein, the terms "alkyl", "alkenyl", "alkynyl" etc. include substituted and unsubstituted groups. In certain embodiments, as used herein, "aliphatic" is used to represent those aliphatic groups (cyclic, acyclic, substituted, unsubstituted, branched or non-branched) with 1-20 carbon atoms. Substituents for aliphatic groups include, but are not limited to, any of the substituents described herein that result in the formation of a stable moiety (e.g., aliphatic, alkyl, alkenyl, alkynyl, heteroaliphatic, heterocyclic, aryl, heteroaryl, acyl, oxo, imino, thiooxo, cyano, isocyano, amino, azido, nitro, hydroxy, thiol, halogen, aliphatic amino, heteroaliphatic amino, alkylamino, heteroalkylamino, arylamino, heteroarylamino, alkylaryl, arylalkyl, aliphatic oxy, heteroaliphatic oxy, alkoxy, heteroalkoxy, aryloxy, heteroaryloxy, aliphatic thioxy, heteroaliphatic thioxy, alkylthioxy, heteroalkylthioxy, arylthioxy, heteroarylthioxy, acyloxy, and the like, each of which may be further substituted or unsubstituted).

As used herein, the term "alkyl" has its common meaning in the art and refers to a saturated aliphatic group, including straight-chain alkyl, branched-chain alkyl, cycloalkyl (alicyclic) groups, alkyl-substituted cycloalkyl and cycloalkyl-substituted alkyl. In some cases, the alkyl group can be a lower alkyl group, i.e., an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl). In some embodiments, a straight-chain or branched-chain alkyl group can have 30 or less carbon atoms in its main chain, and in some cases, can have 20 or less carbon atoms. In some embodiments, a straight-chain or branched-chain alkyl group can have 12 or less carbon atoms (e.g., C ₁ -C ₁₂ for straight chain, C ₃ -C ₁₂ for branched chain), 6 or less, or 4 or less carbon atoms in its main chain. Similarly, a cycloalkyl group can have 3-10 carbon atoms in the ring structure, or 5, 6 or 7 carbon atoms in the ring structure. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, tert-butyl, cyclobutyl, hexyl, and cyclohexyl.

As used herein, the term "alkylene" refers to a divalent alkyl group. An "alkylene" is a polymethylene group, i.e., -(CH ₂ )z-, where z is a positive integer, such as 1 to 20, 1 to 10, 1 to 6, 1 to 4, 1 to 3, 1 to 2, or 2 to 3. A substituted alkylene chain is a polymethylene group in which one or more methylene hydrogen atoms are replaced by a substituent. Suitable substituents include those described herein for substituted aliphatic groups.

Typically, the prefix "sub" is used to describe a divalent group. Thus, any term defined herein may be modified with the prefix "sub" to describe the divalent form of the moiety. For example, a divalent carbocycle is a "carbocyclylene," a divalent aromatic ring is an "arylene," a divalent benzene ring is a "phenylene," a divalent heterocycle is a "heterocyclylene," a divalent heteroaryl ring is a "heteroarylene," a divalent alkyl chain is an "alkylene," a divalent alkenyl chain is an "alkenylene," a divalent alkynyl chain is an "alkynylene," a divalent heteroalkyl chain is a "heteroalkylene," a divalent heteroalkenyl chain is a "heteroalkenylene," a divalent heteroalkynyl chain is a "heteroalkynylene," and the like.

The terms "alkenyl" and "alkynyl" have their ordinary meaning in the art and refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond, respectively.

In certain embodiments, the alkyl, alkenyl, and alkynyl groups used in the present invention contain 1-20 aliphatic carbon atoms. In certain other embodiments, the alkyl, alkenyl, and alkynyl groups used in the present invention contain 1-10 aliphatic carbon atoms. In yet other embodiments, the alkyl, alkenyl, and alkynyl groups used in the present invention contain 1-8 aliphatic carbon atoms. In yet other embodiments, the alkyl, alkenyl, and alkynyl groups used in the present invention contain 1-6 aliphatic carbon atoms. In yet other embodiments, the alkyl, alkenyl, and alkynyl groups used in the present invention contain 1-4 carbon atoms. Therefore, illustrative aliphatic groups include, but are not limited to, for example, methyl, ethyl, n-propyl, isopropyl, allyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, tert-pentyl, n-hexyl, sec-hexyl moieties, etc., which may also carry one or more substituents. Alkenyl groups include, but are not limited to, for example, vinyl, propenyl, butenyl, 1-methyl-2-butene-1-yl, etc. Representative alkynyl groups include, but are not limited to, ethynyl, 2-propynyl (propargyl), 1-propynyl, and the like.

The term "cycloalkyl" as used herein specifically refers to a group having 3 to 10, preferably 3 to 7 carbon atoms. Suitable cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like, which, as with other aliphatic, heteroaliphatic, or heterocyclic moieties, may be optionally substituted with substituents including, but not limited to, aliphatic; heteroaliphatic; aryl; heteroaryl; arylalkyl; heteroarylalkyl; alkoxy; aryloxy; heteroalkoxy; heteroaryloxy; alkylthio; arylthio; heteroalkylthio; heteroarylthio; -F; -Cl; -Br; -I; -OH; _-NO2 ; -CN; _-CF3 ; _-CH2CF3 ; _-CHCl2 ; _-CH2OH ; -CH2CH2OH _{; -CH2NH2 ; -CH2SO2CH3} ; -C(O) _Rx ; _-CO2 (Rx ₎ ; _-CON (Rx) ₂ ; -OC(O)Rx; _-OCO2 Rx; -OCON(Rx) ₂ ; -N(Rx) ₂ ; -S(O) _2Rx ; -NRx(CO)Rx, wherein each occurrence of Rx independently includes, but is not limited to, aliphatic, heteroaliphatic, aryl, heteroaryl, arylalkyl, or heteroarylalkyl, wherein any aliphatic, heteroaliphatic, arylalkyl, or heteroarylalkyl substituent described above and herein may be substituted or unsubstituted, branched or unbranched, cyclic or acyclic, and wherein any aryl or heteroaryl substituent described above and herein may be substituted or unsubstituted. Additional examples of generally suitable substituents are illustrated by the specific embodiments shown in the Examples described herein.

As used herein, the term "heteroaliphatic" refers to an aliphatic moiety as defined herein, including saturated and unsaturated, non-aromatic, linear (i.e., non-branched), branched, acyclic, cyclic (i.e., heterocycle) or polycyclic hydrocarbons, which are optionally substituted with one or more functional groups and contain one or more oxygen, sulfur, nitrogen, phosphorus or silicon atoms, for example, in place of carbon atoms. In certain embodiments, the heteroaliphatic moiety is substituted by independently replacing one or more hydrogen atoms thereon with one or more substituents. It will be understood by those of ordinary skill in the art that "heteroaliphatic" is intended herein to include, but is not limited to, heteroalkyl, heteroalkenyl, heteroalkynyl, heterocycloalkyl, heterocycloalkenyl and heterocycloalkynyl moieties. Therefore, the term "heteroaliphatic" includes the terms "heteroalkyl," "heteroalkenyl," "heteroalkynyl," etc. In addition, as used herein, the terms "heteroalkyl," "heteroalkenyl," "heteroalkynyl," etc. include substituted and unsubstituted groups. In certain embodiments, as used herein, "heteroaliphatic" is used to refer to heteroaliphatic groups (cyclic, acyclic, substituted, unsubstituted, branched or unbranched) having 1-20 carbon atoms. Heteroaliphatic substituents include, but are not limited to, any of the substituents described herein that result in the formation of a stable moiety (e.g., aliphatic, alkyl, alkenyl, alkynyl, heteroaliphatic, heterocycle, aryl, heteroaryl, acyl, sulfinyl, sulfonyl, oxo, imino, thiooxo, cyano, isocyano, amino, azido, nitro, hydroxy, thiol, halogen, aliphatic amino, heteroaliphatic amino, alkylamino, heteroalkylamino, arylamino, heteroarylamino, alkylaryl, arylalkyl, aliphatic oxy, heteroaliphatic oxy, alkoxy, heteroalkoxy, aryloxy, heteroaryloxy, aliphatic thioxy, heteroaliphatic thioxy, alkylthioxy, heteroalkylthioxy, arylthioxy, heteroarylthioxy, acyloxy, and the like, each of which may be further substituted or unsubstituted).

The term "heteroalkyl" has its ordinary meaning in the art and refers to an alkyl group as described herein in which one or more carbon atoms are replaced by a heteroatom. Suitable heteroatoms include oxygen, sulfur, nitrogen, phosphorus, and the like. Examples of heteroalkyl groups include, but are not limited to, alkoxy, amino, thioester, poly(ethylene glycol) groups, and alkyl-substituted amino groups.

The terms "heteroalkenyl" and "heteroalkynyl" have their ordinary meaning in the art and refer to unsaturated aliphatic groups analogous in length and possible substitution to the heteroalkyl groups described above, but that contain at least one double or triple bond, respectively.

Some examples of substituents for the aliphatic (and other) portions of the compounds of the invention described above include, but are not limited to, aliphatic; heteroaliphatic; aryl; heteroaryl; alkylaryl; alkylheteroaryl; alkoxy; aryloxy; heteroalkoxy; heteroaryloxy; alkylthio; arylthio; heteroalkylthio; heteroarylthio; F; Cl; Br; I; -OH; _-NO2 ; -CN; -CF3; _-CHF2 ; _-CH2F ; _-CH2CF3 ; _-CHC12 ; _-CH2OH ; -CH2CH2OH; -CH2NH2; -CH2SO2CH3; _{-C (} O _{) Rx ;} -CO2(Rx ₎ ; -CON(Rx _{) 2} ; -OC(O _{) Rx} ; -OCO2Rx; -OCON(Rx) _{2 ;} -N(Rx) ₂ ; -S( _O ) ₂ Rx; -NRx(CO)Rx, wherein each occurrence of Rx independently includes, but is not limited to, an aliphatic, alicyclic, heteroaliphatic, heterocyclic, aryl, heteroaryl, alkylaryl, or alkylheteroaryl group, wherein any aliphatic, heteroaliphatic, alkylaryl, or alkylheteroaryl substituent described above and herein may be substituted or unsubstituted, branched or unbranched, cyclic or acyclic, and wherein any aryl or heteroaryl substituent described above and herein may be substituted or unsubstituted. Additional examples of generally suitable substituents are illustrated by the specific embodiments shown in the Examples described herein.

The term "aryl" has its ordinary meaning in the art and refers to an aromatic carbocyclic group that is optionally substituted and has a single ring (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple fused rings of which at least one is aromatic (e.g., 1,2,3,4-tetrahydronaphthyl, naphthyl, anthracenyl, or phenanthrenyl). That is, at least one ring may have a conjugated π electron system, while the other adjacent rings may be cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, and/or heterocyclic groups. The aryl group may be optionally substituted as described herein. Substituents include, but are not limited to, any of the aforementioned substituents, i.e., those listed for the aliphatic portion or for the other portions disclosed herein that result in the formation of a stable compound. In some cases, the aryl group is a stable mono- or polycyclic unsaturated moiety preferably having 3-14 carbon atoms, each of which may be substituted or unsubstituted. "Carbocyclic aryl" refers to an aryl group in which the ring atoms on the aromatic ring are carbon atoms. Carbocyclic aryl groups include monocyclic carbocyclic aryl groups and polycyclic or fused ring compounds (eg, two or more adjacent ring atoms are common to two adjoining rings), such as naphthyl.

The term "heteroaryl" has its ordinary meaning in the art and refers to an aromatic group containing at least one heteroatom as a ring atom. A "heteroaryl" group is a stable heterocyclic or polycyclic unsaturated moiety preferably having 3-14 carbon atoms, each of which may be substituted or unsubstituted. Substituents include, but are not limited to, any of the aforementioned substituents, i.e., substituents listed for the aliphatic moiety or for other moieties disclosed herein that result in the formation of a stable compound. In some cases, a heteroaryl group is a cyclic aromatic group having 5 to 10 ring atoms, wherein one ring atom is selected from S, O, and N; 0, 1, or 2 ring atoms are additional heteroatoms independently selected from S, O, and N; and the remaining ring atoms are carbon, the group being joined to the rest of the molecule via any ring atom, for example, pyridyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isoxazolyl, thiadiazolyl, oxadiazolyl, phenylthio, furanyl, quinolinyl, isoquinolinyl, etc.

It will also be understood that aryl and heteroaryl moieties as defined herein may be attached through an alkyl or heteroalkyl moiety, and thus also include -(alkyl)aryl, -(heteroalkyl)aryl, -(heteroalkyl)heteroaryl, and -(heteroalkyl)heteroaryl moieties. Thus, as used herein, the phrases "aryl or heteroaryl moiety" and "aryl, heteroaryl, -(alkyl)aryl, -(heteroalkyl)aryl, -(heteroalkyl)heteroaryl, and -(heteroalkyl)heteroaryl" are interchangeable. Substituents include, but are not limited to, any of the aforementioned substituents, i.e., those listed for aliphatic moieties, or for other moieties disclosed herein, that result in the formation of stable compounds.

It will be understood that the aryl and heteroaryl groups (including bicyclic aryl groups) may be substituted or unsubstituted, wherein substitution includes independently replacing one or more hydrogen atoms thereon with any one or more of the following moieties, including but not limited to: aliphatic; alicyclic; heteroaliphatic; heterocyclic; aromatic; heteroaromatic; aryl; heteroaryl; alkylaryl; heteroalkylaryl; alkylheteroaryl; heteroalkylheteroaryl; alkoxy; aryloxy; heteroalkoxy; heteroaryloxy; alkylthio; arylthio; heteroalkylthio; heteroarylthio; F _; Cl; Br; I; _-OH ; _-NO2 ; -CN; _-CF3 ; _-CHF2 ; _{-CH2F ; -CH2CF3} ; -CHCl2; _-CH2OH ; _-CH2CH2OH ; _-CH2NH2 ; _{-CH2SO2CH3 ; -C} (O ₎ Rx; _-CO2 -(alkyl)aryl, -(alkyl)aryl, _- (alkyl)aryl, -( _alkyl )aryl, -(alkyl) _aryl , -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, - ₍ alkyl)aryl _, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)aryl, -(alkyl)hetero ...heteroaryl, -(alkyl)aryl, -(alkyl)heteroaryl, -(alkyl)aryl, -(alkyl)heteroaryl, -(alkyl)aryl, -(alkyl)heteroaryl, -(alkyl)aryl, -(alkyl)heteroaryl, -(alkyl)aryl, -(alkyl)heteroaryl, -(alkyl)aryl, -(alkyl)heteroary Furthermore, it will be understood that any two adjacent groups may be taken together to represent a 4, 5, 6, or 7-membered substituted or unsubstituted alicyclic or heterocyclic moiety. Additional examples of generally suitable substituents are illustrated by the specific embodiments described herein.

[0046] As used herein, the terms "halo" and "halogen" refer to an atom selected from fluorine, chlorine, bromine, and iodine.

It should be understood that the above-mentioned groups and/or compounds as described herein may be optionally substituted with any number of substituents or functional moieties. That is, any of the above groups may be optionally substituted. As used herein, the term "substituted" is considered to include all permissible substituents of organic compounds, "permissible" being in the context of chemical valence rules known to those of ordinary skill in the art. In general, the term "substituted", whether or not preceded by the term "optionally", and the substituents included in the formula of the present invention refer to the replacement of hydrogen radicals in a given structure with groups of specified substituents. When more than one position in any given structure can be substituted with more than one substituent selected from a specified group, the substituents may be the same or different at each position. It should be understood that "substituted" also includes substitutions that produce stable compounds, for example, they will not spontaneously transform as by rearrangement, cyclization, elimination, etc. In some cases, "substituted" may generally refer to the replacement of hydrogen with substituents as described herein. However, as used herein, "substituted" does not include replacement and/or alteration of key functional groups by which a molecule is determined, such as by making a "substituted" functional group become a different functional group by substitution. For example, " substituted phenyl " must still contain phenyl moiety, and can not be modified into, for example, pyridine ring by substitution in this definition. In a broad sense, permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. Illustrative substituents include, for example, those described herein. For suitable organic compounds, permissible substituents can be one or more and the same or different. For purposes of the present invention, heteroatoms such as nitrogen can have any permissible substituents of hydrogen substituents and/or organic compounds described herein that satisfy heteroatom valence states. In addition, the present invention is not intended to be limited in any way by the permissible substituents of organic compounds.

Examples of substituents include, but are not limited to, halogen, azido, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxy, alkoxy, amino, nitro, sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, sulfonamido, keto, aldehyde, ester, heterocyclic, aromatic or heteroaromatic moieties, _-CF3 , -CN, aryl, aryloxy, perhaloalkoxy, aralkyloxy, heteroaryl, heteroaryloxy, heteroarylalkyl, heteroaralkyloxy, azido, amino, halide group, alkylthio, oxo, acylalkyl, carboxyl ester group, carbonylamino, acyloxy, aminoalkyl, alkylaminoaryl, alkylaryl, alkylaminoalkyl, alkoxyaryl, arylamino, aralkylamino, alkylsulfonyl, carbonylaminoalkylaryl, carbonylaminoaryl, hydroxyalkyl, haloalkyl, alkylaminoalkylcarboxyl, aminocarbonylaminoalkyl, cyano, alkoxyalkyl, perhaloalkyl, arylalkoxyalkyl, etc.

These and other aspects of the invention will become further apparent upon consideration of the following examples, which are intended to illustrate certain specific embodiments of the invention but are not intended to limit its scope as defined by the claims.

Example

Example 1. Synthesis of a chain-extended polyurethane dispersion with glycerol carbonate (CCARB) end groups (EG) (Binder A) using non-stoichiometric amounts of end monomers, low solvent content, catalysis, and post-dispersion chain extension

Under a nitrogen atmosphere, a 1 L three-necked flask was charged with 24.50 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI), 3.29 g of DMPA (dimethylolpropionic acid), 70.80 g of poly(propylene glycol) (Mn~2,000), and 7.58 g of YmerN120. 0.057 g of dibutyltin dilaurate was then added, and the mixture was heated to 68-71°C. After 5.5 hours, 4.61 g of glycerol carbonate was added to the reaction mixture and stirred for an additional 2 hours, at which point 1.44 g of N-methyl-2-pyrrolidone (NMP) was added to reduce the viscosity. After another hour, triethylamine (2.28 g) was added and stirred for 15 minutes, at which point the prepolymer was dispersed in 167 g of deionized water (DIW) at 39°C. The prepolymer was added over 15 minutes. A solution of HMDA (0.631 g) in DIW (10.3 g) was added dropwise to the dispersion over 12 minutes.After a further 60 minutes a clear, slightly opaque dispersion was isolated.

Example 2. Synthesis of a polyurethane dispersion using a mixture of terminal monomers, catalysis, and post-dispersion chain extension—glycerol carbonate/3-aminopropyltrimethoxysilane (Binder B)

Under a nitrogen atmosphere, 76.12 g of poly(propylene glycol) (Mn~2,000), 8.806 g of YmerN120 (Perstorp), and 4.193 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask. 28.6 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 0.060 g of dibutyltin dilaurate were added, and the mixture was heated to 75-76 ° C for 3.5 hours. Glyceryl carbonate (2.946 g) was added and heated for an additional 3 hours. TEA (3.71 g) was added, and after 15 minutes, the prepolymer was dispersed in 202 g of DIW at ~39 ° C within 10 minutes. After mixing for a further 5 minutes at 1000 rpm, a solution of HMDA (2.09 g) in DIW (15.0 g) and 3-aminopropyltrimethoxysilane (2.216 g) were added dropwise to the dispersion over 10 minutes, and after a further 60 minutes a clear, translucent dispersion was isolated.

Example 3. Synthesis of a polyurethane dispersion using a mixture of terminal monomers, catalysis, and post-dispersion chain extension—glycerol carbonate/3-aminopropyltrimethoxysilane (Binder C)

Under a nitrogen atmosphere, 65.56 g of poly(propylene glycol) (Mn~2,000), 7.866 g of YmerN120 (Perstorp), and 3.611 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask. 24.7 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 0.049 g of dibutyltin dilaurate were added, and the mixture was heated to 75-76 ° C for 3.5 hours. Glyceryl carbonate (1.586 g) was added and the reaction was heated for another 2.5 hours. TEA (3.03 g) was added, and after 15 minutes, the prepolymer was dispersed into 175 g of DIW at ~39 ° C over 15 minutes. After mixing for a further 5 minutes at 900 rpm, a solution of HMDA (1.26 g) in DIW (15.3 g) and 3-aminopropyltrimethoxysilane (3.13 g) were added dropwise to the dispersion over a period of 20 minutes. After a further 100 minutes, a clear, translucent dispersion was isolated.

Example 4. Synthesis of a chain-extension-free polyurethane dispersion - glycerol carbonate (binder D) using stoichiometric amounts of terminal monomers in a solvent with catalytic, dropwise addition of reagents

Under a nitrogen atmosphere, 33.20 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 91.70 g of poly(propylene glycol) (Mn~2,000) were added to a 1 L three-necked flask. 0.097 g of dibutyltin dilaurate was added, and the mixture was heated to 68-70°C. After 4.5 hours, 18.36 g of a mixture of 6.985 g of DMPA (dimethylolpropionic acid) and 14.75 g of NMP was added directly to the reactor and stirred for an additional 1.5 hours, after which the reactor was cooled and stirring was discontinued overnight. The next day, the mixture was reheated to 75-77°C for 5 hours, followed by the addition of 8.704 g of glycerol carbonate. After another 3 hours, heating and stirring were terminated.

114.7 g of the above prepolymer mixture was transferred to a second reactor and heated to 70° C. 2.7 g of TEA (triethylamine) was added and stirred for 45 minutes, after which the prepolymer was dispersed into 163.5 g of DIW at 45° C. over 30 minutes. After another 30 minutes, a translucent dispersion was isolated.

Example 5. Synthesis of a chain-extended polyurethane dispersion using stoichiometric amounts of terminal monomers - catalyzed, reverse addition of DIW - glycerol carbonate (binder E)

Under a nitrogen atmosphere, 35.76g H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI), 6.31g DMPA (dimethylolpropionic acid) and 98.36g poly(propylene glycol) (Mn~2,000) were added to a 500ml three-necked flask. 0.076g dibutyltin dilaurate was added, and the mixture was first heated to 72°C for 2 hours and then to 80°C for 4 hours. 9.33g glycerol carbonate was added and heated for 1.5 hours, and then heating and stirring were terminated. After 15 hours, the mixture was reheated to 70-75°C for 1.5 hours, followed by the addition of 3.54g TEA (triethylamine). After mixing for 45 minutes, 266.0g of DIW was added over 45 minutes while mixing at 750rpm and cooled to 38-40°C. The milky dispersion was mixed for another 1.5 hours and then separated.

Example 6. Synthesis of a polyurethane dispersion with chain extension after dispersion using non-stoichiometric amounts of terminal monomers in solvent, catalyzed—glycerol carbonate EG (binder F)

Under a nitrogen atmosphere, a 1 L three-necked flask was charged with 31.82 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI), 5.79 g of DMPA (dimethylolpropionic acid), 87.20 g of poly(propylene glycol) (Mn ~2,000), and 2.11 g of NMP. 0.064 g of dibutyltin dilaurate was then added, and the mixture was heated to 78-80°C. After 4.5 hours, 4.56 g of glycerol carbonate and 0.93 g of NMP were added to the reaction mixture and stirred for an additional 4 hours, at which point the reaction was cooled to 70°C. TEA (4.08 g) and NMP (1.9 g) were added and stirred for 20 minutes, at which point the prepolymer was dispersed into 197 g of DIW at ~42°C. The prepolymer was added over 10 minutes, followed by mixing at 1000 rpm for an additional 5 minutes. A 35.4% solution of HMDA in DIW (4.61 g) was diluted with an additional 10.02 g of DIW and added dropwise to the dispersion over 15 minutes. After a further 30 minutes, a clear, slightly opaque dispersion was isolated.

Example 7. Synthesis of a polyurethane dispersion using a terminal monomer mixture, catalyzed, and chain extended after dispersion—glycerol carbonate/2-hydroxyethylpyrrolidone (HEP) EG (Binder G)

Under a nitrogen atmosphere, 76.40 g of poly(propylene glycol) (Mn~2,000), 9.284 g of YmerN120 (Perstorp), and 4.433 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask. 31.2 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 0.060 g of dibutyltin dilaurate were then added, and the mixture was heated to 75-76°C for 5 hours, after which a mixture of 4.828 g of glycerol carbonate (3.35 g) and 2-hydroxyethylpyrrolidone (3.653 g) was added and stirred for an additional 3.5 hours. TEA (3.61 g) was added, and 15 minutes later, the prepolymer was dispersed into 202 g of DIW at ~39°C over 15 minutes, followed by mixing at 750 rpm for an additional 5 minutes. A solution of HMDA (2.09 g) in water (10.0 g) DIW was added dropwise to the dispersion over 10 minutes. After a further 60 minutes a clear, translucent dispersion was isolated.

Example 8. Synthesis of Polyurethane Dispersion Using Stoichiometric End-Monomer Mixture - Glycerol Carbonate/2-Hydroxyethylpyrrolidone (Binder H)

Under a nitrogen atmosphere, 95.50g of poly(propylene glycol) (Mn~1,000), 9.99g of YmerN120 (Perstorp) and 7.77g of DMPA (dimethylol propionic acid) were added to a 1L three-necked flask. 54.4g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) was then added and the mixture was heated to 75-80°C for 5 hours, followed by a mixture of 10.71g of glycerol carbonate (4.43g) and 2-hydroxyethylpyrrolidone (10.23g) and stirred for an additional 2 hours. The temperature was lowered to 55°C and mixed for an additional 20 hours. The reaction temperature was raised to 75°C, at which point TEA (4.58g) was added. After 30 minutes, the prepolymer was dispersed into 310g of DIW at ~39°C. The prepolymer was added over 30 minutes and then mixed overnight at ambient temperature. A clear, translucent dispersion was isolated.

Example 9. Synthesis of Polyurethane Dispersion Using Stoichiometric End-Monomer Mixture - Glycerol Carbonate/2-Hydroxyethylpyrrolidone EG (Binder J)

Under a nitrogen atmosphere, 158.3 g of poly(propylene glycol) (Mn~2,000), 10.60 g of Ymer N120 (Perstorp) and 10.19 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask at 30°C. 58.13 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) was then added and the mixture was heated to 100°C for 5.5 hours. The temperature was lowered to 80°C, a mixture of 10.60 g of glycerol carbonate (4.378 g) and 2-hydroxyethylpyrrolidone (9.552 g) was added, and stirred for another hour. The temperature was lowered to 55°C and mixed for another 20 hours. The reaction temperature was lowered to 70°C and mixed for another 21 hours overnight. TEA (7.15 g) was added and after 15 minutes the prepolymer was dispersed into 462 g of DIW at 50° C. The prepolymer was added over 70 minutes, at which point the temperature was raised to 65° C. over 1.5 hours. After mixing overnight at ambient temperature, a clear, translucent dispersion was isolated.

Example 10. Synthesis of a polyurethane dispersion using a non-stoichiometric end-group monomer mixture, catalyzed, and chain-extended after dispersion—2-hydroxyethylpyrrolidone/3-aminopropyltrimethoxysilane (Binder L)

Under a nitrogen atmosphere, 74.818 g of poly(propylene glycol) (Mn~2,000), 8.515 g of YmerN120 (Perstorp) and 4.054 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask. 27.435 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 0.057 g of dibutyltin dilaurate were added, and the mixture was heated to 76-78 ° C for 3.5 hours. 2-Hydroxyethylpyrrolidone (3.034 g) was added and heated for an additional 3 hours. TEA (3.628 g) was added, and after 10 minutes, the prepolymer was dispersed into 178 g of DIW at ~39 ° C within 15 minutes. After mixing for another 5 minutes at 900 rpm, a solution of HMDA (2.824 g) in DIW (12.557 g) and 3-aminopropyltrimethoxysilane (1.206 g) were added dropwise to the dispersion over 25 minutes. After another 90 minutes, the dispersion was isolated.

Example 11. Synthesis of a polyurethane dispersion using a non-stoichiometric end-monomer mixture, catalyzed, and chain extended after dispersion—glycerol carbonate/3-hydroxypropionitrile (Binder M)

Under a nitrogen atmosphere, 76.532g of poly(propylene glycol) (Mn~2,000), 9.148g of YmerN120 (Perstorp) and 4.129g of DMPA (dimethylol propionic acid) were added to a 1L three-necked flask. 30.024g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) and 0.062g of dibutyltin dilaurate were added, and the mixture was heated to 75-77°C for 3.5 hours. A mixture of 3.97g of glycerol carbonate (5.006g) and 3-hydroxypropionitrile (1.656g) was added, and the reaction was heated for another 2.5 hours. TEA (2.75g) was added, and after 15 minutes, the prepolymer was dispersed into 176g of DIW at ~39°C within 10 minutes. With mixing at 750 rpm, a solution of HMDA (1.773 g) in DIW (10.0 g) was added dropwise to the dispersion over 10 minutes. Another 64.5 g of DIW was added, and after a further 30 minutes the dispersion was isolated.

Example 12. Synthesis of a polyurethane dispersion using a non-stoichiometric end-monomer mixture, uncatalyzed, and chain-extended after dispersion—glycerol carbonate/2-hydroxyethylpyrrolidone EG (binder O)

Under a nitrogen atmosphere, 200.3g of poly(propylene glycol) (Mn~2,000), 13.86g of Ymer N120 (Perstorp) and 14.72g of DMPA (dimethylol propionic acid) were added to a 1L three-necked flask at 30°C. 95.1g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) was then added and the mixture was heated to 100°C for 3.5 hours, after which polymerization was essentially complete (monitored by mid-infrared spectroscopy). The temperature was reduced to 80°C, a mixture of 16.84g of glycerol carbonate (6.656g) and 2-hydroxyethylpyrrolidone (14.419g) was added, and stirred for an additional 16 hours. The temperature was reduced to 78°C and TEA (10.54g) was added. After 75 minutes, the prepolymer was dispersed into 625 g of DIW at 40° C. over 30 minutes, followed by chain extension for another 10 minutes using a mixture of HMDA (5.51 g) in DIW (10.8 g). The reaction temperature was raised to 55° C. for 1 hour, after which heating was terminated and the dispersion was mixed overnight at ambient conditions to produce a clear, translucent product.

Example 13. Synthesis of Polyurethane-Acrylic Hybrid Adhesive A

Under a nitrogen atmosphere, 120.0 g of poly(propylene glycol) (Mn~1,000), 12.90 g of YmerN120 (Perstorp) and 9.72 g of DMPA (dimethylol propionic acid) were added to a 1 L three-necked flask. 68.37 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) was then added, and the mixture was heated to 100° C. for 4.5 hours. After cooling to 80° C., a mixture of 11.98 g of glycerol carbonate (4.24 g) and 2-hydroxyethylpyrrolidone (9.71 g) was added and stirred for 1 hour. The temperature was lowered to 70° C. and mixed for an additional 16.5 hours. The temperature of the heating oil was raised to 77° C., at which time TEA (6.28 g) was added. After 40 minutes, the prepolymer was dispersed into 433 g of DIW at -45°C over 35 minutes, followed by heating to -50°C for one hour. A clear, translucent polyurethane dispersion was isolated.

To a 1 L three-necked flask was added 265.0 g of a translucent polyurethane dispersion (35.0% solids), 10.7 g of butyl acrylate, 4.3 g of glycidyl methacrylate, and 0.42 g of 4,4′-azobis(4-cyanovaleric acid). The mixture was stirred at 500 rpm for 90 minutes, at which point it was heated to 70° C. under a nitrogen atmosphere. An additional 54 g of DIW was added, and heating was continued for a total of 21 hours. After cooling to ambient temperature, the thin, whitish dispersion was collected.

Example 14. Synthesis of Polyurethane-Acrylic Hybrid Adhesive B

Under a nitrogen atmosphere, 179.4 g of poly(propylene glycol) (Mn ~ 2,000), 6.54 g of YmerN120 (Perstorp), and 15.02 g of DMPA (dimethylolpropionic acid) were added to a 1 L three-necked flask. 72.91 g of H12MDI (4,4'-methylenebis(cyclohexylisocyanate), hydrogenated MDI) was then added, and the mixture was heated to 100°C for 4.5 hours. After cooling to 80°C, a mixture of 15.71 g of glycerol carbonate (6.36 g) and 2-hydroxyethylpyrrolidone (13.79 g) was added and stirred for 21 hours. 9.65 g of TEA was added and stirred for 2.5 hours, after which the prepolymer was dispersed into 548 g of DIW at ~ 50°C over 30 minutes. The dispersion was heated to 60°C for 1 hour, then mixed overnight at ambient temperature. A clear, thin polyurethane dispersion was isolated.

To a 1 L three-necked flask was added 251.5 g of a thin polyurethane dispersion (33% solids), 12.7 g of butyl acrylate, 4.7 g of glycidyl methacrylate, 6.3 g of 2-ethylhexyl methacrylate, 32.8 g of DIW, and 0.28 g of 4,4'-azobis(4-cyanovaleric acid). The mixture was stirred at 400 rpm for 25 minutes, at which point it was heated to 70-80°C under a nitrogen atmosphere for 7.5 hours. 0.12 g of AIBN was added, and mixing was continued at 68-70°C for 19 hours. After cooling to ambient temperature, the thin, whitish dispersion was collected.

Example 15. General overcoating method and test display structure

This example illustrates the general overcoating method and display structure testing used in subsequent examples unless otherwise noted.

Using a slot die or linear bar coater, the previously applied and dried ink on a first release substrate (3-layer as shown in Figure 1D) or electrode substrate (2-layer as shown in Figure 1C) is coated with an adhesive fluid (prepared by mixing the corresponding polyurethane dispersion with a specified amount of crosslinker(s)) to the specified dry coating weight. The ink-adhesive coating is then dried in an oven at the specified temperature and dwell time before being laminated to the electrode substrate (3-layer) or release substrate (2-layer). For 3-layer systems, the first release substrate is removed from the ink surface, and the ink surface is then laminated to a smooth side laminate (SSL) adhesive (e.g., adhesive layer 140 in Figure 1D). 2-layer structures do not require an additional lamination step prior to constructing the test structure. The two intermediate structures (2-layer or 3-layer) are then processed into test display structures by cutting sections of appropriate size, removing the remaining release backing, and laminating to the appropriate backplane electrode. Conditioning of the test displays is generally performed after conditioning at 25°C and 50% relative humidity (RH), unless alternative conditions are required.

Example 16. Electro-optical properties of polyurethane adhesives

Table 1 shows the t ₀ EO state of cyclic carbonate-modified polyurethanes coated on one or more types of ink layers compared to a comparative laminate control (aqueous polyurethane dispersion) laminated to the ink layer in a 3-layer structure. The wet film thickness of the topcoat was ~4 mils, equivalent to a coating weight of ~25 g/m ^2. The 3-layer pixels were conditioned at 25°C and 50% RH. Adhesive C contained a lower content of cyclic carbonate functional groups than Adhesive B. It was observed that the experimental adhesives achieved significantly improved white state (WS), dark state (DS), and dynamic range (DR) L* values when compared to the comparative laminate pixels. Although the total dynamic range achieved by the adhesives and control adhesives of Table 1 is relatively similar, WS and DS can be manipulated by varying the cyclic carbonate content as shown. The cyclic carbonate functional group content in Adhesive A is slightly higher than that in Adhesive B, and explains why its WS image stability is slightly worse (see the following section). Cyclic carbonate functional groups also result in very low DS L* values, as exemplified by Adhesive A.

Table 1.

Figures 5A-5B show the adjusted 30-second image stability traces of an experimental polyurethane overcoated onto the ink layer compared to a control adhesive laminated onto the ink layer. The 3 layers were pixel conditioned at 25°C and 50% RH. Figures 5A-5B show the effect of cyclic carbonate functionality content on the 30-second image stability of WS and DS. Both adhesives resulted in minimal WS bounce with stable WS L* (Figure 5B), or minimal WS L* improvement with improved L* values. Similar improvement behavior was observed for DS L* stability, but a slightly larger increase was observed for WS.

The magnitude and direction of the WS L* drift can be controlled by the content of the cyclic carbonate functional groups added. Figures 6-7 illustrate this effect. Low levels of cyclic carbonate cause WS L* to increase over time, while very high levels cause WS L* to decrease within 30 seconds. As shown in Figure 8, there is a correlation between the mole % content of the cyclic carbonate functional groups added and the degree of WS L* drift. The optimal cyclic carbonate functional group content is about 10 mole %.

Example 17. Effect of end group type

Figure 8 compares the effects of pyrrolidone and cyclic carbonate end-capping groups. Both functional groups are five-membered heterocyclic rings with one or two carbon atoms interposed between the ring and the oxygen bound to the polyurethane chain. When incorporated into the polyurethane backbone at equimolar concentrations, significantly better image stability was observed for the polyurethane containing cyclic carbonate, clearly demonstrating the influence of functional group type.

This effect on the t ₀ state is shown in Table 2. In the Adhesive B series, the pixels laminated with the comparative laminate (control) showed an overall WS loss from the initial state to 30 seconds, while the pixels coated with the pyrrolidone-containing adhesive showed an overall WS improvement. The 3 layers of pixels were conditioned at 25°C and 50% RH and are from 2 separate experiments as shown. The pixels coated with the cyclic carbonate-containing adhesive had a stable WS while showing a slightly improved WS L* for the laminate system. Similar observations were made in the Adhesive A series, but in this case the WS L* shift of the laminate pixels was lower. The improved DR L* values of all the coated pixels containing cyclic carbonate functional groups relative to the control were due to the significantly improved DS L* values.

Table 2

Figure 9 shows a 240 millisecond WS L* pulse trace for Adhesive M overcoated to the ink layer compared to a control laminate laminated to the same ink. Adhesive M incorporates cyclic carbonate functionality and acid functionality for curing. Both adhesives were coated at ~25 g/m ² using a 5 mil thick electrode. A 3 L* increase in WS was observed for the overcoated ink (with an equivalent DS L* trace).

Example 18. Regarding ITO ink structure

The ink was applied to a transparent, flexible substrate coated with indium tin oxide. Subsequently, a water-based adhesive formulation containing a dispersed polyurethane and a carbodiimide crosslinker (reactive with the carboxyl functional groups in the polyurethane) was bar-coated and dried at high temperature in a horizontal suction oven. The carbodiimide crosslinker content was matched to the acid functional groups present in the polyurethane, resulting in an acid/carbodiimide functional group ratio of approximately 1:1.

Table 3 shows the change in initial dynamic range δL* (relative to the comparative laminate) as a function of end group modification. It was observed that comparable initial properties were achieved with the carbonate-modified polyurethane relative to the comparative (control) laminating ink.

Table 3

Imposition δ(DR) cyano group outer coating -3 Pyrrolidone outer coating -1 n-Butyl outer coating -3 Carbamate outer coating -2 Carbonate outer coating 0 comparison Laminated materials 0

Figure 10 shows the loss in WS L* over time during electrical stress testing at 25°C for overcoated adhesives on machine coated DTI open inks. The data are relative to t=0 for each single adhesive. All overcoated adhesives were crosslinked with a carbodiimide crosslinker at a 1:1 acid:carbodiimide equivalent. The comparative laminate (control) was not crosslinked and contained 180 ppm of ionic dopant. It was unexpectedly found that the introduction of pendant cyclic carbonate functional groups resulted in an enhanced resistance to stress degradation at 25°C that was comparable to the comparative laminating ink. This behavior was not observed for the other end-group modified polyurethanes studied.

Example 19. Improved low temperature performance

Another property improvement observed with carbonate-modified polyurethanes is improved low temperature performance, i.e., switching behavior and resulting L* values. Table 4 lists the EO data accumulated at 0°C. The carbonate-modified adhesives showed the best switching behavior at 0°C.

Table 4

WS L*0C DS L*0C DR L*0C cyano group 66.1 31.3 34.8 Pyrrolidone 66.8 33.3 33.4 Butyl 61.7 34.9 26.8 Carbamate 64.3 33 31.3 Carbonate 69.2 21.4 47.7

Examples 20-23 generally relate to low coat weight adhesive films.

Example 20. Low Coating Weight Overcoating

Surprisingly, by manipulating the rheology of the polyurethane and the type and rate of the curing method, overcoating of the ink and subsequent void-free lamination to the electrode substrate can be achieved using relatively low adhesive coating weights. Typically, for adhesives used in commercial and advanced prototype displays, defects such as lamination voids and orange peel increase with decreasing coating weight, and at least ~25 g/ ^m2 of material is required to achieve acceptable performance. The adhesives described herein significantly reduce the amount of material required for void-free lamination and reduced orange peel.

Table 5 lists the coating weight, void count, and orange peel of an ink-binder-electrode structure, in which an adhesive containing carboxylic acid, cyclic carbonate, and acrylate functional groups was overcoated onto the ink layer on a release substrate using a linear rod coater. A dry coating weight of 6 g/ ^m² (approximately 1 mil wet coating thickness) was achieved using a 30% solids aqueous adhesive formulation. As shown in the data, virtually void-free lamination of the electrode to the ink surface was achieved. Furthermore, the orange peel value is within the range typically observed with existing commercial adhesive coating weights of 25 g/ ^m² . The adhesive characteristics were selected to balance the adhesive's Tc (e.g., to influence material flow into the ink surface; thinner films require reduced amounts of adhesive to planarize the electro-optical layer prior to cure, typically resulting in lower adhesive Tc values), the degree of crosslinking (acid-carbodiimide), and solvent evaporation during the first cure to achieve flow and filling of rough ink surfaces and subsequent void-free lamination (e.g., after a second cure) to both 5-mil and 1-mil electrode substrates.

Table 5

Table 5 shows the coating weight, void count, and orange peel value of Adhesive N for laminating 5 mil and 1 mil electrodes to an ink layer of open ink overcoated onto a release layer.

Table 6 shows another example illustrating the benefits of the combination of functional groups that improve the electro-optical state and a dual cure approach to achieve low coating weights. In this case, Adhesive M was overcoated to a prototype ink on a peel ply at low and high wet film builds (4 mils wet equivalent to ~20-25 g/m ² and 1.5 mils wet equivalent to ~8-10 g/m ² ), then laminated to a 5 mil electrode substrate and constructed into a 3-layer graphite pixel. As can be seen from the data and the image stability traces in the accompanying Figure 11, improved WS L* and DR L* values were obtained with Adhesive M: the lower coating weight of the overcoated material resulted in better WS image stability, lower bounce levels, and improved electro-optical state. Although the initial DS L* values were higher than those observed for the comparative laminate control, the lower DS SE levels resulted in almost equivalent 30 second DS L* values.

Table 6

Table 6 shows the 25°C electro-optical data for Adhesive M of the prototype ink overcoated onto a release layer at low and high wet film build, illustrating the impact of electro-optically active functional groups and low coating weight adhesive. The 3-layer pixel was cured at 50°C/50% RH and reconditioned at 25°C/50% RH before measurement.

Example 21. Lamination to open ink

In this embodiment, the adhesive is applied to the electrode substrate (e.g., 3-layer structure) or to the release substrate (e.g., 2-layer structure), and then laminated to the ink surface. A second cure is then performed to achieve the final mechanical and electro-optical property development of the two interfaces.

Adhesive B (acid, cyclic carbonate, silane functionality) and Adhesive L (acid, pyrrolidone, silane functionality) were both mixed with a carbodiimide crosslinker (for Stage I cure (first cure)) and applied to a release substrate at 1.5 mil wet build (approximately 7-9 g/ ^m2 of dry adhesive), dried in a hood oven, and laminated to a prototype ink on a 1 mil electrode substrate. The adhesive surface was either laminated directly to a carbon backing or to a commercial SSL, which was then laminated to a carbon backing. Stage II cure (second cure) was provided by the trimethoxysilane functionality introduced via a condensation mechanism. As a comparative example, an open ink on a 1 mil electrode substrate was laminated to an SSL (2 layers of 5 g/ ^m2 adhesive weight each; total coating weight of 10 g/ ^m2 ). The SSL was minimally crosslinked to enable a direct comparison of the effects of adhesive rheology and dual cure on lamination quality. Some void formation was evident in the comparative example (observed indirectly by the switching effect), whereas the pixels with Adhesive B showed no evidence of lamination voids when switched. Additionally, as shown in Table 8, improved WS L* values were obtained with Adhesive B.

Table 7.

Table 7 shows the initial and 30-second L* values for 2- or ^3- layer DTI pixels of Adhesive B ^and Adhesive L of the prototype inks laminated to a 1-mil electrode substrate, compared to a 2-layer pixel made using two layers of commercial SSL (5 g/m 2 adhesive weight; 10 g/m 2 total adhesive coating weight) laminated to a 1-mil electrode. The experimental adhesives were coated to a wet bar height of ~1.5 mils on a 1-mil electrode, equivalent to ~7-9 g/m ² of dry adhesive.

Additional examples of electro-optical improvements that can be obtained by laminating adhesives are shown in Table 8. In this case, the adhesive was applied to a 5 mil electrode substrate at a 3.5 mil wet coating thickness, dried, and laminated to a prototype ink on a peel-off substrate. A comparative aqueous polyurethane dispersion (control) was used as a comparison. At 30 seconds, a WS L* of 76 and a DSL* of 18 were observed for the adhesive.

Table 8

Table 8 shows the 25°C t=0 electro-optical data for Adhesive M laminated to a prototype open ink compared to a comparative control laminated to the same ink. Pixels are 3 layers of graphite conditioned at 25°C and 50% RH.

Example 22. Curing of mixed adhesive

The rheological profile of mixed adhesive A is shown in Figure 12. The profile is shown before and after curing. In Figure 12, the shear storage modulus (G') and shear loss modulus (G") of the Stage I (thermoplastic drying) and Stage II (acid-epoxy covalent crosslinking) cured adhesives are plotted as a function of temperature. The combination of the high temperature plateau in G' and the relatively low tan δ of the crosslinked (Stage II cured) material indicates cure efficiency. The crossover temperature (Tc) of the polyurethane, i.e., the temperature at which tan δ (the ratio of loss modulus to storage modulus) equals 1 and the material begins to exhibit a relatively viscous flow, is used to estimate the relative ease with which the adhesive planarizes the ink surface during drying and lamination. As can be seen in the tan δ plot (not shown), the Tc of hybrid adhesive A, cured by Stage I (thermoplastic drying), is approximately 10-15°C higher than that of the parent unmodified polyurethane, making it generally suitable for use as a planarizing adhesive at low coat weights. The improved rheology achieved with the hybrid adhesive would require significantly higher coat weights of adhesive layers to effectively planarize the ink surface using commercial adhesives.

Hybrid Adhesive A was applied by overcoating the adhesive fluid onto the open ink, drying in a heated oven (Stage I cure), laminating to a peelable substrate, followed by Stage II cure (chemical crosslinking), resulting in an ink-adhesive coating that was relatively thin (total ink-adhesive thickness of approximately 23-24 microns) and had very low levels of void defects. A corresponding commercially available ink-adhesive coating was approximately 40 microns thick. Figures 13-14 are SEM micrographs of a cross-section of a two-layer ink-adhesive stack with Hybrid Adhesive A applied at 8 g/m ² (dry coating weight), demonstrating a flattened and relatively defect-free (void) adhesive-ink interface, and the total thickness of the ink-adhesive coating is shown. High-temperature stress testing of a test glass display made from this frontplane laminate (FPL) did not result in any defect formation, confirming the development of adequate mechanical properties after Stage II cure.

Example 23. Polyurethane Adhesives with Multiple Crosslinking Agents

In this example, a polyurethane with a relatively low Tc is combined with two different crosslinking agents that differ in their relative rates of crosslinking with reactive functional groups on the polyurethane backbone. Stage I crosslinking is achieved during drying and lamination of the adhesive application, providing the desired rheological properties that enable subsequent processing steps. Stage II crosslinking primarily occurs during the cure conditioning cycle of the FPL. For example, Figure 15 shows the use of carbodiimide and epoxy crosslinkers for polyurethanes (PUs) with significantly different crosslinking rates.

A polyurethane dispersion was mixed with 2 wt% epoxy and 4.8 wt% carbodiimide, overcoated as an open ink on PET-ITO, dried, and laminated to a low-surface-energy release substrate. After the drying/lamination stage, the carbodiimide crosslinker cures relatively completely, while the epoxy crosslinker cures subsequently at 60°C over 5 days. The rheological profile of the adhesive system (Adhesive J) is plotted in Figure 16. The curves are shown before and after cure (via Stage II). In FIG16 , the shear storage modulus (G′) and shear loss modulus (G″) are plotted as a function of temperature. The combination of a high temperature plateau in G′ and a relatively low tan δ for the cured material indicates cross-linking efficiency. FIG17A-17B are SEM micrographs of a cross-section of a 2-layer ink-adhesive stack with Adhesive J coated at 7 g/m ² , showing a flat and relatively defect-free (void) adhesive-ink interface, and the total thickness of the ink-adhesive coating is shown. High temperature stress testing of a test glass display made from this FPL did not result in the formation of any defects, confirming the development of adequate mechanical properties after cross-linking.

Example 24. Dual-cure adhesive using two cross-linking agents

The following examples illustrate dual cure comprising two cross-linking based cures.

Adhesives, such as Adhesive J, are synthesized using a polyurethane dispersion with a mixture of end monomers—glycerol carbonate/2-hydroxyethylpyrrolidone. Dual (covalent) crosslinking cure utilizes the carboxylic acid functional groups on the polyurethane to react with carbodiimide and epoxy crosslinkers. Adhesive J is used with the following amounts of crosslinker:

Sample I: Sample I: 4.8 wt% carbodiimide crosslinker (single cure)

Sample II: 8.0 wt% carbodiimide crosslinker (single cure)

Sample III: 4.8 wt% carbodiimide crosslinker + 2.1 wt% epoxy crosslinker (dual cure)

Sample IV: 8.0 wt% carbodiimide crosslinker + 1.0 wt% epoxy crosslinker (dual cure)

Using the above method, the crosslinker consumption during stage I curing (oven drying + ambient holding + hot lamination) was monitored. After the applied adhesive fluid was oven dried, the carbodiimide functional group loss of samples I and II at ambient temperature was plotted as a function of time. The carbodiimide loss was then quantified using the ratio of the carbodiimide peak area to the CH peak area. The residual carbodiimide content after 2 hours was a function of the initial carbodiimide content, but was relatively low in both samples. This indicates that at the end of stage I curing (oven drying + ambient holding + hot lamination), even at the higher of the two carbodiimide levels, the carbodiimide crosslinker had been essentially completely consumed before stage II curing.

Although several embodiments of the present invention have been described and illustrated herein, a person of ordinary skill in the art will readily devise various other means and/or structures for performing the functions and/or obtaining the results and/or one or more advantages described herein, and each such variation and/or modification is considered to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary, and that actual parameters, dimensions, materials, and/or configurations may vary depending on the specific application or applications in which the teachings of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using only routine experimentation, many equivalents to the specific embodiments of the present invention described herein. Therefore, it should be understood that the foregoing embodiments are presented by way of example only, and that, within the scope of the appended claims and their equivalents, the present invention may be practiced otherwise than as specifically described and claimed. The present invention relates to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods is included within the scope of the present invention, provided that such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent.

All patent applications and patents incorporated herein by reference are hereby incorporated by reference in their entirety. In the event of a conflict, this specification, including definitions, will control. In the event that this specification and a document incorporated by reference contain conflicting and/or inconsistent disclosures, this specification will control. If two or more documents incorporated by reference contain conflicting and/or inconsistent disclosures, the document with the later effective date will control.

Unless expressly indicated to the contrary, the indefinite articles "a" and "an" as used herein should be understood to mean "at least one".

As used herein, the phrase "and/or" should be understood to mean "either or both" of the elements so combined, i.e., elements that are present in combination in some cases and separately in other cases. In addition to the elements specifically identified by the "and/or" clause, other elements may optionally be present, whether related or unrelated to those specifically identified elements, unless expressly indicated to the contrary. Thus, as a non-limiting example, when used in conjunction with open language such as "comprising," a reference to "A and/or B" may, in one embodiment, refer to A without B (optionally including other elements in addition to B); in another embodiment, to B without A (optionally including other elements in addition to A); in yet another embodiment, to both A and B (optionally including other elements); and so on.

As used herein, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" or "and/or" should be interpreted as inclusive, i.e., including at least one of the numerous or listed elements, but also including more than one, and optionally additionally unlisted items. Only when the term is clearly indicated to the contrary, such as "only one of" or "exactly one of", or when used in a claim, "consisting of..." will refer to the inclusion of exactly one element or a list of elements. In general, when preceded by an exclusive term, such as "either", "one of", "only one of" or "exactly one of", the term "or" as used herein should only be interpreted as indicating exclusive alternatives (i.e., "one or the other but not both"). When used in a claim, "essentially consisting of..." should have its ordinary meaning as used in the field of patent law.

Claims (15)

1. An electro-optic component comprising a polyurethane layer including a first type of end-capping group and a second type of end-capping group, wherein the first type of end-capping group is a cyclic carbonate of formula (XII): in: R ¹ is selected from hydrogen, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted halogroup and hydroxyl. L is a linking group, which may be absent by choice; n is 1-4; and Indicates the location of the bond connected to the polyurethane; and The second type of end-capping group is pyrrolidone. 2. The electro-optical assembly of claim 1, wherein L is an optionally substituted alkylene group or an optionally substituted heteroalkylene group. 3. The electro-optical component as claimed in claim 1, wherein ^R1 is hydrogen. 4. The electro-optical assembly of claim 1, wherein the pyrrolidone comprises formula (XVI): in: Each R ² is the same or different, and is selected from hydrogen, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted heteroaryl; M is a linking group, which may optionally be absent; and This indicates the location of the bond connected to the polyurethane. 5. The electro-optical assembly of claim 4, wherein M is an optionally substituted alkylene group or an optionally substituted heteroalkylene group. 6. The electro-optic component of claim 1, wherein the polyurethane layer further comprises a third type of end-capping group, the third type of end-capping group comprising a silane of formula (XXXIII): in: L is a linking group, which may be absent by choice; Each ^R3 is either the same or different, and contains -( _CH2 ) _n- or -O-( _CH2 ) _n ; Each n is either the same or different, and is between 1 and 4; and This indicates the location of the bond connected to the polyurethane. 7. The electro-optical assembly of claim 6, wherein L is an optionally substituted alkylene group or an optionally substituted heteroalkylene group. 8. The electro-optical assembly of claim 1, wherein the ratio of the cyclic carbonate end-capping group to the second type of end-capping group is 1:2 to 2:1. 9. The electro-optical assembly of claim 1, wherein the polyurethane is formed by reacting a diisocyanate compound with at least one type of diol, followed by a reaction with a cyclic carbonate end-capping agent and a second type of end-capping agent comprising pyrrolidone. 10. The electro-optical assembly of claim 9, wherein the diisocyanate is 4,4'-methylenebis(cyclohexyl isocyanate). 11. The electro-optical assembly of claim 1, wherein the end-capped cyclic carbonate is provided in a weight percentage of 2% to 10% relative to the total composition which does not contain any solvent. 12. The electro-optical assembly of claim 1, wherein the end-capped cyclic carbonate is provided as 5-15 mol% of polyurethane. 13. The electro-optic component of claim 1, wherein the first type of end-capping group and the second type of end-capping group are provided in a weight percentage of 2% to 10% by weight relative to the total composition which does not contain any solvent. 14. An electro-optical display comprising the electro-optical component as claimed in claim 1. 15. The electro-optic display of claim 14, wherein the electro-optic component comprises an encapsulated electrophoretic medium.