TWI858273B - Optical laminate and image display device including polarizing plate with phase difference layer of the optical laminate - Google Patents

Abstract

The present invention provides an optical laminate, which includes a thin polarizing plate with a phase difference layer having excellent bending properties, and in which adhesive loss, adhesive contamination and cutting defects are suppressed during cutting. The optical multilayer body of the present invention comprises: a polarizing plate with a phase difference layer, which comprises: a polarizing plate, a first phase difference layer bonded to the side opposite to the viewing side of the polarizing plate via a first adhesive layer, a second phase difference layer bonded to the first phase difference layer via a second adhesive layer, and an adhesive layer provided on the side opposite to the first phase difference layer of the second phase difference layer; a surface protection film temporarily bonded to the viewing side of the polarizing plate with a phase difference layer in a removable manner; and a spacer temporarily bonded to the adhesive layer of the polarizing plate with a phase difference layer in a removable manner. When the thickness of the adhesive layer is set to T _PSA , the thickness of the polarizer with phase difference layer is set to T _PWR , and the thickness of the optical laminate is set to T _OL , the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4

T _PSA /T _OL ≦0.29.

Description

Optical laminate and image display device including a polarizing plate with a phase difference layer attached to the optical laminate

The present invention relates to an optical multilayer body and an image display device including a polarizing plate with a phase difference layer attached to the optical multilayer body.

In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices) are rapidly becoming popular. In image display devices, polarizing plates and phase difference plates are typically used. From a practical point of view, polarizing plates with phase difference layers obtained by integrating polarizing plates, phase difference plates and adhesive layers are widely used (for example, Patent Document 1). Recently, as the demand for thinner image display devices has become increasingly strong, the demand for thinner polarizing plates with phase difference layers has also become increasingly strong. In addition, in recent years, the demand for curved image display devices and/or bendable or foldable image display devices has been increasing. However, the thin and highly bendable polarizing plate with phase difference layer that can be used in such image display devices has the problem of adhesive missing (the end of the adhesive layer is missing), adhesive contamination (the end of the adhesive layer is stained), and poor cutting when cut into a specific size or shape.

Prior art literature Patent Literature

Patent document 1: Japanese Patent No. 3325560

The present invention is completed to solve the above-mentioned previous problems. The main purpose is to provide an optical laminate, which includes a thin polarizing plate with a phase difference layer having excellent bending properties, and the adhesive loss, adhesive contamination and poor cutting during cutting are suppressed.

The optical laminate of the present invention comprises: a polarizing plate with a phase difference layer, which comprises: a polarizing plate including a polarizing element and a protective layer at least on the viewing side of the polarizing element, a first phase difference layer bonded to the side opposite to the viewing side of the polarizing plate via a first adhesive layer, and a second phase difference layer bonded to the first phase difference layer via a second adhesive layer. A second phase difference layer, and an adhesive layer disposed on the side of the second phase difference layer opposite to the first phase difference layer; a surface protection film temporarily adhered to the viewing side of the polarizing plate with the phase difference layer in a removable manner; and a spacer temporarily adhered to the adhesive layer of the polarizing plate with the phase difference layer in a removable manner. When the thickness of the adhesive layer is set to T _PSA , the thickness of the polarizing plate with the phase difference layer is set to T _PWR , and the thickness of the optical laminate is set to T _OL , the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4

T _PSA /T _OL ≦0.29.

Another optical multilayer system of the present invention satisfies the following relationship when the thickness of the adhesive layer is set to T _PSA , the thickness of the polarizing plate with phase difference layer is set to T _PWR , and the thickness of the spacer is set to T _SP : T _PSA /T _PWR ≧0.4

T _SP /T _PSA ≧0.8.

In one embodiment, the T _PSA , T _PWR , T _OL and T _SP of the optical laminate satisfy the following relationship: T _PSA /T _PWR ≧0.4

T _PSA /T _OL ≦0.29

T _SP /T _PSA ≧0.8.

In one embodiment, the thickness T _PSA of the adhesive layer is greater than 20 μm.

In one embodiment, the thickness of the polarizing element is less than 8 μm.

In one embodiment, the storage modulus of the adhesive layer at 25° C. is 1.0×10 ⁴ Pa to 1.0×10 ⁶ Pa.

In one embodiment, the thickness T _PWR of the polarizing plate with phase difference layer is less than 100 μm.

In one embodiment, the polarizing plate has a protective layer only on the viewing side of the polarizing element.

In one embodiment, the first phase difference layer and the second phase difference layer are alignment solidification layers of liquid crystal compounds, respectively.

In one embodiment, the Re(550) of the first phase difference layer is 200nm~300nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element is 10°~20°; the Re(550) of the second phase difference layer is 100nm~190nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element is 70°~80°.

According to another aspect of the present invention, an image display device is provided. The image display device has the above-mentioned polarizing plate with phase difference layer of the above-mentioned optical laminate.

In one embodiment, the image display device is an organic electroluminescent display device.

According to the present invention, the following optical laminate can be realized, which includes a thin polarizing plate with a phase difference layer having excellent bending properties, a surface protection film, and a separator, and by optimizing the mutual relationship among the thickness of the optical laminate, the thickness of the polarizing plate with a phase difference layer, the thickness of the adhesive layer, and the thickness of the separator, the adhesive loss, adhesive contamination, and poor cutting during cutting are suppressed.

10: Polarizing plate

11: Polarizing element

12: Protective layer

21: 1st phase difference layer

22: Second phase difference layer

31: First subsequent agent layer

32: Second subsequent agent layer

40: Adhesive layer

50: Surface protection film

60: Isolation parts

70: Polarizing plate with phase difference layer

100: Optical multilayers

Figure 1 is a schematic cross-sectional view of an optical multilayer body according to one embodiment of the present invention.

The following describes the implementation methods of the present invention, but the present invention is not limited to these implementation methods.

(Definition of terms and symbols)

The definitions of terms and symbols in this manual are as follows.

(1) Refractive index (nx, ny, nz)

"nx" is the refractive index in the direction with the largest refractive index in the plane (i.e. the direction of the latent axis), "ny" is the refractive index in the direction orthogonal to the latent axis (i.e. the direction of the advanced axis), and "nz" is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

"Re(λ)" is the in-plane phase difference measured at 23°C with light of wavelength λ nm. For example, "Re(550)" is the in-plane phase difference measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set to d(nm), Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d.

(3) Phase difference in thickness direction (Rth)

"Rth(λ)" is the phase difference in the thickness direction measured at 23°C with light of wavelength λ nm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C with light of wavelength 550nm. When the thickness of the layer (film) is set to d(nm), Rth(λ) is calculated by the formula: Rth(λ)=(nx-nz)×d.

(4) Nz coefficient

The Nz coefficient is calculated by Nz=Rth/Re.

(5) Angle

In this manual, when an angle is mentioned, the angle includes both clockwise and counterclockwise directions relative to the reference direction. Therefore, for example, "45°" means ±45°.

A. The overall structure of the polarizing plate with phase difference layer

FIG1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in the figure comprises: a polarizing plate 70 with a phase difference layer, a surface protection film 50 temporarily attached to the visual side of the polarizing plate 70 with a phase difference layer in a removable manner, and a spacer 60 temporarily attached to the side opposite to the visual side of the polarizing plate 70 with a phase difference layer in a removable manner. The polarizing plate 70 with a phase difference layer typically comprises a polarizing plate 10, a first phase difference layer 21, and a second phase difference layer 22 in order from the visual side. The polarizing plate 10 comprises a polarizing element 11 and a protection layer 12 on the visual side of the polarizing element 11. Depending on the purpose, another protective layer (not shown) may be provided on the side opposite to the visual side of the polarizing element 11. The first phase difference layer 21 is bonded to the side opposite to the visual side of the polarizing plate 10 via the first adhesive layer 31. The second phase difference layer 22 is bonded to the side opposite to the visual side of the first phase difference layer 21 via the second adhesive layer 32. From a practical point of view, an adhesive layer 40 is provided on the side of the second phase difference layer 22 opposite to the first phase difference layer 21 (i.e., the outermost layer on the side opposite to the visual side), and the polarizing plate with the phase difference layer can be attached to the image display unit. The spacer 60 is temporarily attached to the surface of the adhesive layer 40 in a removable manner. By temporarily attaching the spacer, the roll formation of the optical laminate can be performed while protecting the adhesive layer. The surface protection film 50 typically has a substrate and an adhesive layer (neither of which are shown), and is temporarily attached to the polarizing plate with a phase difference layer (substantially the viewing side protection layer 12) in a removable manner via the adhesive layer. When the optical laminate (essentially a polarizing plate with a phase difference layer) is actually used, the spacer 60 is peeled off and removed, and the polarizing plate 70 with a phase difference layer is attached to the image display device (essentially an image display unit) via the adhesive layer 40. The surface protection film 50 is also peeled off and removed when the optical laminate (essentially a polarizing plate with a phase difference layer) is actually used.

The first phase difference layer 21 and the second phase difference layer 22 are representatively alignment cured layers of liquid crystal compounds, respectively. By using liquid crystal compounds, the difference between nx and ny of the obtained phase difference layer can be significantly greater than the difference between nx and ny of non-liquid crystal materials, so the thickness of the phase difference layer used to obtain the required in-plane phase difference can be significantly reduced. As a result, a significant thinning of the polarizing plate with a phase difference layer can be achieved. In this specification, the so-called "alignment cured layer" refers to a layer in which the liquid crystal compound is aligned in a specific direction within the layer and its alignment state is fixed. Furthermore, the concept of "alignment cured layer" includes an alignment cured layer obtained by curing a liquid crystal monomer as described below. In the first phase difference layer 21 and the second phase difference layer 22, the rod-shaped liquid crystal compound is typically aligned in a state of being aligned in the direction of the retardation axis of the first phase difference layer or the second phase difference layer (horizontally aligned). Typically, either the first phase difference layer 21 or the second phase difference layer 22 can function as a λ/2 plate, and the other can function as a λ/4 plate. For example, when the first phase difference layer 21 can function as a λ/2 plate and the second phase difference layer 22 can function as a λ/4 plate, the Re(550) of the first phase difference layer 21 is preferably 200nm~300nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element 10 is preferably 10°~20°; the Re(550) of the second phase difference layer 22 is preferably 100nm~190nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element 10 is preferably 70°~80°.

In one embodiment of the present invention, when the thickness of the optical laminate 100 is set to T _OL , the thickness of the polarizer 70 with a phase difference layer is set to T _PWR , the thickness of the adhesive layer 40 is set to T _PSA , and the thickness of the spacer 60 is set to T _SP , the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4

T _PSA /T _OL ≦0.29.

When T _PSA /T _PWR is 0.4 or more, it means that, typically, in a polarizing plate with a phase difference layer having a thinner overall thickness, the thickness of the adhesive layer is thicker. For example, when attempting to apply a polarizing plate with a phase difference layer to a bendable or foldable image display device, the previous polarizing plate with a phase difference layer cannot ensure the bending property that can withstand use in such an image display device. In contrast, by making the overall thickness thinner and making the adhesive layer relatively thicker, a polarizing plate with a phase difference layer having a specific bending property can be realized. The inventors of the present invention have discovered a new topic, namely, when such a polarizing plate with a phase difference layer is cut into a specific size or a specific shape, there may be a lack of adhesive, adhesive contamination and/or poor cutting. The inventors of the present invention speculate that since the ratio of adhesives with lower elasticity is larger than that of films, the deformation of the adhesive layer during cutting may be related to the topic. Based on the speculation, the inventors of the present invention have conducted intensive research and found that the topic can be solved by controlling the thickness of the surface protective film and the spacer temporarily attached to the polarizing plate with a phase difference layer, and setting the T _PSA /T _OL to less than 0.29, thereby completing the present invention. That is, by controlling the thickness of the surface protection film and the spacer, the overall (i.e., apparent) elastic modulus of the optical laminate is increased, and the force applied to the adhesive layer during cutting is reduced (resulting in reduced deformation of the adhesive layer during cutting), adhesive loss, adhesive contamination, and poor cutting during cutting of the polarizing plate with a phase difference layer can be suppressed without changing the preferred structure of the polarizing plate with a phase difference layer actually used. Furthermore, as described in the following examples, it was confirmed that, for example, regarding adhesive contamination, when T _PSA /T _OL was about 0.3, 100% of adhesive contamination occurred, while when T _PSA /T _OL was about 0.28, the rate of adhesive contamination dropped sharply to 20%. In other words, it was found that T _PSA /T _OL had a critical value near 0.29. As described above, the optical laminate of the embodiment of the present invention is a new issue for solving the polarizing plate with a phase difference layer, and its effect is of key significance and unexpectedly excellent.

In another embodiment of the present invention, the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4

T _SP /T _PSA ≧0.8.

Based on the same speculation and research findings as above, the inventors have found that by setting T _SP /T _PSA to 0.8 or above, the above new issues (adhesive missing, adhesive contamination and/or poor cutting during cutting) of a thin polarizing plate with a phase difference layer having excellent bending properties for use in a bendable or foldable image display device can be solved. More specifically, by increasing the thickness of the spacer adjacent to the adhesive layer, it is very helpful to prevent deformation of the adhesive during cutting, and as a result, adhesive missing, adhesive contamination and poor cutting during cutting can be suppressed.

Preferably, the T _PSA , T _PWR , T _OL and T _SP of the optical laminate satisfy the following relationship: T _PSA /T _PWR ≧0.4

T _PSA /T _OL ≦0.29

T _SP /T _PSA ≧0.8.

T _PSA /T _PWR is preferably 0.42 to 0.75, more preferably 0.45 to 0.65. T _PSA /T _OL is preferably 0.25 or less, more preferably 0.20 or less, and further preferably 0.18 or less. T _PSA /T _OL may be, for example, 0.10 or more. _{T SP} /T _PSA is preferably 0.9 or more, more preferably 1.2 or more, and further preferably 1.4 or more. _{T SP} /T _PSA may be, for example, 3.0 or less.

The total thickness of the polarizing plate with a phase difference layer is preferably less than 100 μm, more preferably less than 85 μm, further preferably less than 70 μm, and particularly preferably less than 60 μm. The lower limit of the total thickness may be, for example, 42 μm. The polarizing plate with a phase difference layer having such a total thickness may have extremely excellent flexibility and bendability. As a result, the polarizing plate with a phase difference layer is particularly suitable for use in a curved image display device and/or a bendable or foldable image display device.

The polarizing plate with phase difference layer may further include other optical functional layers. The type, characteristics, quantity, combination, and configuration position of the optical functional layers of the polarizing plate with phase difference layer may be appropriately set according to the purpose. For example, the polarizing plate with phase difference layer may further have a conductive layer or an isotropic substrate with a conductive layer (neither of which is shown in the figure). The conductive layer or the isotropic substrate with a conductive layer is typically arranged on the outside of the second phase difference layer 22 (the side opposite to the polarizing plate 10). The conductive layer or the isotropic substrate with a conductive layer is typically an arbitrary layer provided as needed, and may also be omitted. Furthermore, when a conductive layer or an isotropic substrate with a conductive layer is provided, a polarizing plate with a phase difference layer can be applied to a so-called internal touch panel type input display device in which a touch sensor is assembled between an image display unit (e.g., an organic EL unit) and a polarizing plate. For another example, a polarizing plate with a phase difference layer can further include other phase difference layers. The optical properties (e.g., refractive index properties, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, configuration position, etc. of other phase difference layers can be appropriately set according to the purpose.

The above-mentioned embodiments may be appropriately combined, and the components in the above-mentioned embodiments may be modified as known in the industry, or the components in the above-mentioned embodiments may be replaced with optically equivalent components.

The optical laminate can be in the form of a single sheet or a strip. In this specification, the so-called "strip" refers to a long and narrow shape whose length is sufficiently long relative to its width, for example, a long and narrow shape whose length is more than 10 times, preferably more than 20 times, of its width. The strip-shaped polarizing plate with a phase difference layer can be rolled into a roll.

The following is a more detailed description of the components of the polarizing plate with phase difference layer.

B. Polarizing plate

B-1. Polarizing element

As the polarizing element 11, any appropriate polarizing element can be used. For example, the resin film forming the polarizing element can be a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizing elements composed of a single-layer resin film include: polyvinyl alcohol (PVA) films, partially formalized PVA films, ethylene-vinyl acetate copolymer partially saponified films, etc., which are dyed and stretched with dichroic substances such as iodine or dichroic dyes; polyene alignment films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. In terms of excellent optical properties, it is preferable to use a polarizing element obtained by dyeing a PVA film with iodine and uniaxially stretching it.

The dyeing using iodine is performed, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching can be performed after the dyeing treatment, or it can be performed while dyeing. In addition, the stretching can be performed first and then dyeing. The PVA film can be subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. as needed. For example, by immersing the PVA film in water and washing it before dyeing, not only can the stains and anti-adhesive agent on the surface of the PVA film be washed, but the PVA film can also be swollen to prevent uneven dyeing.

Specific examples of polarizing elements obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. The polarizing element obtained by using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by the following method: a PVA-based resin solution is coated on the resin substrate, and the PVA-based resin layer is formed on the resin substrate by drying, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed, and the PVA-based resin layer is set as a polarizing element. In this embodiment, stretching typically includes immersing the laminate in a boric acid aqueous solution for stretching. Furthermore, stretching can further include, as needed, stretching the laminate in the air at a high temperature (e.g., above 95° C.) before stretching in a boric acid aqueous solution. The obtained resin substrate/polarizing element laminate can be used directly (i.e., the resin substrate can be used as a protective layer of the polarizing element), or the resin substrate can be peeled off from the resin substrate/polarizing element laminate and any appropriate protective layer that meets the purpose can be used on the peeled off area layer. The details of the manufacturing method of such a polarizing element are described in, for example, Japanese Patent Publication No. 2012-73580 and Japanese Patent No. 6470455. All the records in these publications are cited in this specification as a reference.

The thickness of the polarizing element is preferably 15 μm or less, more preferably 1 μm to 12 μm, further preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. If the thickness of the polarizing element is within this range, the above-mentioned required T _PSA /T _PWR and T _PSA /T _OL can be easily achieved. Furthermore, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

The polarizing element preferably exhibits absorption dichroism at any wavelength between 380nm and 780nm. The single transmittance of the polarizing element is preferably 41.5% to 46.0%, more preferably 43.0% to 46.0%, and further preferably 44.5% to 46.0%. The polarization degree of the polarizing element is preferably above 97.0%, more preferably above 99.0%, and further preferably above 99.9%.

B-2. Protective layer

The protective layer 12 and other protective layers (if present) are each formed of any appropriate film that can be used as a protective layer of a polarizing element. Specific examples of the material that is the main component of the film include: cellulose resins such as triacetyl cellulose (TAC); polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyether sulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, (meth)acrylic resins, acetate resins, and the like. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic resins, urethane resins, (meth)acrylic urethane resins, epoxy resins, silicone resins, and the like can also be cited. In addition, for example, glassy polymers such as siloxane polymers can also be cited. In addition, the polymer film described in Japanese Patent Publication No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imine group on the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl and nitrile group on the side chain can be used, for example, a resin composition containing an alternating copolymer of isobutylene and N-methylbutylene diimide and an acrylonitrile-styrene copolymer can be cited. The polymer film can be, for example, an extruded product of the above resin composition.

The polarizing plate with phase difference layer is described below. Typically, it is arranged on the viewing side of the image display device, and the protective layer 12 is arranged on the viewing side. Therefore, the protective layer 12 can be subjected to surface treatments such as hard coating, anti-reflection, anti-sticking, and anti-glare treatments as needed. Furthermore/or, the protective layer 12 can also be subjected to treatments to improve visibility when viewed through polarized sunglasses as needed (typically, (elliptical) circular polarization function and ultra-high phase difference are given). By implementing such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized sunglasses or other polarized lenses. Therefore, polarizing plates with phase difference layers are also suitable for use in image display devices that can be used outdoors.

The thickness of the protective layer 12 is preferably 5μm~80μm, more preferably 10μm~40μm, and further preferably 10μm~30μm. Furthermore, when surface treatment is performed, the thickness of the protective layer 12 includes the thickness of the surface treatment layer.

Other protective layers (if present) are preferably optically isotropic in one embodiment. The term "optically isotropic" in this specification means that the in-plane phase difference Re(550) is 0nm~10nm, and the phase difference Rth(550) in the thickness direction is -10nm~+10nm. The thickness of other protective layers is preferably 5μm~80μm, more preferably 10μm~40μm, and further preferably 10μm~30μm. In terms of thinness, it is preferred that other protective layers be omitted.

C. 1st phase difference layer and 2nd phase difference layer

As described above, the first phase difference layer 21 and the second phase difference layer 22 (hereinafter sometimes collectively referred to as phase difference layer) are respectively the alignment solidification layers of the liquid crystal compound (hereinafter referred to as the liquid crystal alignment solidification layer). As the liquid crystal compound, for example, a liquid crystal compound whose liquid crystal phase is a nematic phase (nematic liquid crystal) can be cited. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The manifestation mechanism of the liquid crystal property of the liquid crystal compound can be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer can be used separately or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinking monomer. The reason is that by polymerizing or crosslinking (i.e. curing) the liquid crystal monomer, the alignment state of the liquid crystal monomer can be fixed. After the liquid crystal monomer is aligned, for example, if the liquid crystal monomers are polymerized or crosslinked with each other, the above alignment state can be fixed. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but they are non-liquid crystal. Therefore, the phase difference layer formed will not undergo a transition to a liquid crystal phase, a glass phase, or a crystalline phase due to temperature changes that are unique to liquid crystal compounds. As a result, the phase difference layer becomes a phase difference layer with extremely excellent stability that is not affected by temperature changes.

The temperature range in which liquid crystal monomers exhibit liquid crystal properties varies depending on their type. Specifically, the temperature range is preferably 40℃~120℃, more preferably 50℃~100℃, and most preferably 60℃~90℃.

As the above-mentioned liquid crystal monomer, any appropriate liquid crystal monomer can be used. For example, polymerizable liquid crystal original base compounds described in Japanese Patent Table 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. As specific examples of such polymerizable liquid crystal original base compounds, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767 can be cited. As a liquid crystal monomer, for example, a nematic liquid crystal monomer is preferred.

The liquid crystal alignment curing layer can be formed by performing an alignment treatment on the surface of a specific substrate, applying a coating liquid containing a liquid crystal compound on the surface, aligning the liquid crystal compound in a direction corresponding to the above-mentioned alignment treatment, and fixing the alignment state. In one embodiment, the substrate is any appropriate resin film, and the liquid crystal alignment curing layer (first phase difference layer 21) formed on the substrate can be transferred to the surface of the polarizing plate 10 via the first adhesive layer 31. Similarly, the liquid crystal alignment curing layer (second phase difference layer 22) formed on the substrate can be transferred to the surface of the first phase difference layer 21 via the second adhesive layer 32.

As the above-mentioned alignment treatment, any appropriate alignment treatment can be adopted. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be cited. As specific examples of mechanical alignment treatment, friction treatment and stretching treatment can be cited. As specific examples of physical alignment treatment, magnetic field alignment treatment and electric field alignment treatment can be cited. As specific examples of chemical alignment treatment, oblique evaporation method and optical alignment treatment can be cited. Any appropriate treatment conditions can be adopted for various alignment treatments according to the purpose.

The alignment of the liquid crystal compound is carried out by treating it at a temperature that exhibits a liquid crystal phase according to the type of the liquid crystal compound. By carrying out such a temperature treatment, the liquid crystal compound becomes a liquid crystal state, and the liquid crystal compound is aligned according to the alignment treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned in the above manner. When the liquid crystal compound is a polymerizable monomer or a crosslinking monomer, the alignment state is fixed by subjecting the liquid crystal compound aligned in the above manner to a polymerization treatment or a crosslinking treatment.

Specific examples of liquid crystal compounds and details of the method for forming an alignment solidified layer are described in Japanese Patent Publication No. 2006-163343. The description in the publication is cited in this specification as a reference.

The typical refractive index characteristics of the phase difference layer show the relationship of nx>ny=nz. Furthermore, "ny=nz" not only refers to the situation where ny and nz are completely equal, but also includes the situation where they are substantially equal. Therefore, within the scope that does not damage the effect of the present invention, there may be a situation where ny>nz or ny<nz.

As described above, either the first phase difference layer 21 or the second phase difference layer 22 can function as a λ/2 plate, and the other can function as a λ/4 plate. Here, the case where the first phase difference layer 21 can function as a λ/2 plate and the second phase difference layer 22 can function as a λ/4 plate will be described, but the opposite is also possible. The thickness of the first phase difference layer 21 can be adjusted in a manner that can obtain the desired in-plane phase difference of the λ/2 plate, for example, it can be 2.0μm~4.0μm. The thickness of the second phase difference layer 22 can be adjusted in a manner that can obtain the desired in-plane phase difference of the λ/4 plate, for example, it can be 1.0μm~2.5μm. The in-plane phase difference Re(550) of the first phase difference layer is as described above, preferably 200nm~300nm, more preferably 230nm~290nm, and further preferably 250nm~280nm. The in-plane phase difference Re(550) of the second phase difference layer is as described above, preferably 100nm~190nm, more preferably 110nm~170nm, and further preferably 130nm~160nm. The angle formed by the retardation axis of the first phase difference layer 21 and the absorption axis of the polarizing element 10 is as described above, preferably 10°~20°, more preferably 12°~18°, and further preferably about 15°. As mentioned above, the angle formed by the retardation axis of the second phase difference layer 22 and the absorption axis of the polarizing element 10 is preferably 70°~80°, more preferably 72°~78°, and further preferably about 75°. With this structure, an ideal characteristic close to the reverse wavelength dispersion characteristic can be obtained, and as a result, a very excellent anti-reflection characteristic can be achieved.

The Nz coefficient of the phase difference layer is preferably 0.9~1.5, and more preferably 0.9~1.3. By satisfying this relationship, when the obtained polarizing plate with a phase difference layer is used in an image display device, a very excellent reflection hue can be achieved.

The phase difference layer can show the reverse dispersion wavelength characteristics where the phase difference value increases according to the wavelength of the measured light, can also show the positive wavelength dispersion characteristics where the phase difference value decreases according to the wavelength of the measured light, and can also show the relatively flat wavelength dispersion characteristics where the phase difference value hardly changes with the wavelength of the measured light.

D. Then the agent layer

The first adhesive layer 31 and the second adhesive layer 32 are collectively described as an adhesive layer. The first adhesive layer and the second adhesive layer may have the same structure or different structures. Any appropriate adhesive may be used as an adhesive constituting the adhesive layer. Representatively, an active energy ray curing adhesive may be cited. Examples of active energy ray curing adhesives include ultraviolet curing adhesives and electron beam curing adhesives. In terms of the curing mechanism, examples of active energy ray curing adhesives include free radical curing, cationic curing, anionic curing, and a mixture of free radical curing and cationic curing. Representatively, free radical curing ultraviolet curing adhesives can be used. The reason is that they are versatile and easy to adjust the characteristics (structure).

烷二醇二丙烯酸酯、EO改性雙甘油四丙烯酸酯、γ-丁內酯丙烯酸 酯、丙烯醯

啉、不飽和脂肪酸羥烷基酯改性ε-己內酯、N-甲基吡咯啶酮、羥乙基丙烯醯胺、N-羥甲基丙烯醯胺、N-甲氧基甲基丙烯醯胺、N-乙氧基甲基丙烯醯胺。該等硬化成分可單獨使用，亦可將2種以上加以併用。 The adhesive typically contains a curing component and a photopolymerization initiator. Typical examples of the curing component include monomers and/or oligomers having functional groups such as (meth)acrylate groups and (meth)acrylamide groups. Specific examples of the curing component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, phenoxy diethylene glycol acrylate, cyclic trihydroxymethyl propane formal acrylate, dimethicone diacrylate, and 1,2-dimethoxy- ...

Alkanediol diacrylate, EO modified diglycerol tetraacrylate, γ-butyrolactone acrylate, acrylamide

Phosphine, unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone, N-methylpyrrolidone, hydroxyethyl acrylamide, N-hydroxymethyl acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide. These hardening components may be used alone or in combination of two or more.

啉、γ-丁內酯丙烯酸酯、不飽和脂肪酸羥烷基酯改性ε-己內酯、N-甲基吡咯啶酮。更佳之硬化成分為不飽和脂肪酸羥烷基酯改性ε-己內酯及丙烯醯

啉，特佳之硬化成分為丙烯醯

啉。相對於硬化成分(存在下述低聚物成分之情形時為硬化成分與低聚物成分之合計)100重量份，具有雜環之硬化成分可較佳為以50重量份以上，更佳為以60重量份以上，進而較佳為以70重量份~95重量份之比率包含於接著劑中。丙烯醯

啉相對於硬化成分(於存在低聚物成分之情形時為硬化成分與低聚物成分之合計)100重量份，可較佳為以5重量份~60重量份，更佳為以10重量份~50重量份之比率包含於接著劑中。 It is preferred that the adhesive contains a curing component having a heterocyclic ring. Examples of the curing component having a heterocyclic ring include: acryl

The preferred hardening component is unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone and acrylamide.

The best curing component is acrylamide

The curing component having a heterocyclic ring is preferably contained in the adhesive in an amount of 50 parts by weight or more, more preferably 60 parts by weight or more, and further preferably 70 parts by weight to 95 parts by weight, relative to 100 parts by weight of the curing component (the total of the curing component and the oligomer component when the oligomer component described below is present).

The phenoxyl group may be contained in the adhesive in an amount of preferably 5 to 60 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the curing component (the total of the curing component and the oligomer component when the oligomer component is present).

基酯、(甲基)丙烯酸2-降

基甲酯、(甲基)丙烯酸5-降

烯-2-基-甲酯、(甲基)丙烯酸3-甲基-2-降

基甲酯等)、含羥基之(甲基)丙烯酸酯類(例如(甲基)丙烯酸羥基乙酯、(甲基)丙烯 酸2-羥基丙酯、(甲基)甲基丙烯酸2,3-二羥丙基甲基-丁酯等)、含烷氧基或苯氧基之(甲基)丙烯酸酯類((甲基)丙烯酸2-甲氧基乙酯、(甲基)丙烯酸2-乙氧基乙酯、(甲基)丙烯酸2-甲氧基甲氧基乙酯、(甲基)丙烯酸3-甲氧基丁酯、乙基卡必醇(甲基)丙烯酸酯、(甲基)丙烯酸苯氧基乙酯等)、含環氧基之(甲基)丙烯酸酯類(例如(甲基)丙烯酸縮水甘油酯等)、含鹵素之(甲基)丙烯酸酯類(例如(甲基)丙烯酸2,2,2-三氟乙基酯、(甲基)丙烯酸2,2,2-三氟乙基乙基酯、(甲基)丙烯酸四氟丙基酯、(甲基)丙烯酸六氟丙基酯、(甲基)丙烯酸八氟戊基酯、(甲基)丙烯酸十七氟癸基酯等)、(甲基)丙烯酸烷基胺基烷基酯(例如(甲基)丙烯酸二甲胺基乙酯等)。作為(甲基)丙烯酸(碳數1~20)烷基酯類之具體例，可例舉：(甲基)丙烯酸甲酯、(甲基)丙烯酸乙酯、(甲基)丙烯酸正丙酯、(甲基)丙烯酸異丙酯、(甲基)丙烯酸2-甲基-2-硝基丙基酯、(甲基)丙烯酸正丁酯、(甲基)丙烯酸異丁酯、(甲基)丙烯酸第二丁酯、(甲基)丙烯酸第三丁酯、(甲基)丙烯酸正戊酯、(甲基)丙烯酸第三戊酯、(甲基)丙烯酸3-戊酯、(甲基)丙烯酸2,2-二甲基丁酯、(甲基)丙烯酸正己酯、(甲基)丙烯酸十六烷基酯、(甲基)丙烯酸正辛酯、(甲基)丙烯酸2-乙基己酯、(甲基)丙烯酸4-甲基-2-丙基戊酯、(甲基)丙烯酸正十八烷基酯。該等(甲基)丙烯酸酯可單獨使用，亦可將2種以上併用。 In addition to the above-mentioned curing components, the adhesive may further contain an oligomer component. By using an oligomer component, the viscosity of the adhesive before curing can be reduced and the operability can be improved. As a representative example of the oligomer component, a (meth)acrylic acid oligomer can be cited. As the (meth)acrylic acid monomer constituting the (meth)acrylic acid oligomer, for example, (meth)acrylic acid (carbon number 1~20) alkyl esters, (meth)acrylic acid cycloalkyl esters (such as (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid cyclopentyl ester, etc.), (meth)acrylic acid aralkyl esters (such as (meth)acrylic acid benzyl ester, etc.), polycyclic (meth)acrylic acid esters (such as (meth)acrylic acid 2-isopropyl ester, etc.),

Ester, 2-nor(meth)acrylate

Methyl ester, 5-nor(meth)acrylate

Alkenyl-2-yl-methyl ester, (meth) acrylic acid 3-methyl-2-

methyl ester, etc.), hydroxyl-containing (meth)acrylates (e.g., hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropylmethyl-butyl (meth)acrylate, etc.), alkoxy- or phenoxy-containing (meth)acrylates (2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, etc.), esters, etc.), epoxy-containing (meth)acrylates (e.g., glycidyl (meth)acrylate, etc.), halogen-containing (meth)acrylates (e.g., 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate, etc.). Specific examples of (meth)acrylic acid (C1-20) alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, hexadecyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, and n-octadecyl (meth)acrylate. These (meth)acrylates may be used alone or in combination of two or more.

Since the photopolymerization initiator can be used in the dosage known to the industry, the detailed description is omitted.

The thickness of the adhesive layer (after the adhesive is cured) is preferably 0.1 μm to 3.0 μm. If the adhesive layer has such a thickness, the above-mentioned required T _PSA /T _PWR and T _PSA /T _OL can be easily achieved.

The details of the adhesive are described in, for example, Japanese Patent Publication No. 2018-017996. The description in the publication is cited in this manual as a reference.

E. Adhesive layer

The storage modulus of the adhesive layer at 25°C is preferably 1.0×10 ⁴ Pa to 1.0×10 ⁶ Pa, more preferably 1.0×10 ⁴ Pa to 1.0×10 ⁵ Pa. If the storage modulus of the adhesive layer is within this range, the adhesive loss, adhesive _{contamination} and poor cutting when cutting _the optical laminate (essentially a _polarizing plate with a phase difference layer) can be suppressed by the synergistic effect with the effect brought about by optimizing the above-mentioned T _PSA /T _PWR , T PSA /T OL and T SP /T _PSA . Furthermore, the storage modulus can be obtained by dynamic viscoelasticity measurement.

The creep amount ΔCr of the adhesive layer at 70°C is, for example, 65 μm or less, and may also be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or even 15 μm or less. The lower limit of the creep amount ΔCr is, for example, 0.5 μm. If the creep amount is within this range, adhesive loss, adhesive contamination, and poor cutting can be suppressed when cutting the optical laminate (essentially a polarizing plate with a phase difference layer). Furthermore, the creep value can be measured, for example, in the following order: on a joint surface of 20 mm in length and 20 mm in width, a load of 500 gf is applied to the adhesive layer attached to a stainless steel test plate in a state where the test plate has been fixed, toward the lead directly below. The creep amount (deviation amount) of the adhesive layer relative to the test plate at each time point 100 seconds and 3600 seconds after the start of the load application is measured and set as Cr ₁₀₀ and Cr ₃₆₀₀ respectively. The creep amount △Cr can be calculated based on the measured Cr ₁₀₀ and Cr ₃₆₀₀ by the formula △Cr=Cr ₃₆₀₀ -Cr ₁₀₀ .

Any suitable composition can be adopted as the adhesive constituting the adhesive layer. Specific examples of the adhesive constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. An adhesive having properties that meet the desired target can be prepared by adjusting the type, amount, combination, and blending ratio of the monomers forming the base resin of the adhesive, the blending amount of the crosslinking agent, the reaction temperature, the reaction time, etc. The base resin of the adhesive can be used alone or in combination of two or more. From the viewpoints of transparency, processability and durability, acrylic adhesives (acrylic adhesive compositions) are preferred. The main component contained in the acrylic adhesive composition is typically a (meth)acrylic polymer. In the solid content of the adhesive composition, the (meth)acrylic polymer can be contained in the adhesive composition at a ratio of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more. The main component contained in the (meth)acrylic polymer is an alkyl (meth)acrylate as a monomer unit. Furthermore, (meth)acrylate refers to acrylate and/or methacrylate. The alkyl (meth)acrylate is preferably contained in the monomer component forming the (meth)acrylic polymer at a ratio of 80% by weight or more, and more preferably 90% by weight or more. As the alkyl group of the (meth)acrylic acid alkyl ester, for example, a linear or branched alkyl group having 1 to 18 carbon atoms can be cited. The average carbon number of the alkyl group is preferably 3 to 9, more preferably 3 to 6. A preferred (meth)acrylic acid alkyl ester is butyl acrylate. As monomers (comonomers) constituting the (meth)acrylic acid polymer, in addition to the (meth)acrylic acid alkyl ester, carboxyl-containing monomers, hydroxyl-containing monomers, amide-containing monomers, aromatic ring-containing (meth)acrylic acid esters, heterocyclic vinyl monomers, etc. can be cited. As representative examples of copolymer monomers, acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone can be cited. The acrylic adhesive composition preferably contains a silane coupling agent and/or a crosslinking agent. Examples of the silane coupling agent include epoxy-containing silane coupling agents. Examples of the crosslinking agent include isocyanate crosslinking agents and peroxide crosslinking agents. Furthermore, the acrylic adhesive composition may also contain an antioxidant and/or a conductive agent. The details of the adhesive layer or the acrylic adhesive composition are described in, for example, Japanese Patent Publication No. 2006-183022, Japanese Patent Publication No. 2015-199942, Japanese Patent Publication No. 2018-053114, Japanese Patent Publication No. 2016-190996, and International Publication No. 2018/008712, and the descriptions of these publications are cited in this specification as references.

The thickness of the adhesive layer is preferably 20 μm or more, more preferably 20 μm to 70 μm, further preferably 20 μm to 65 μm, and particularly preferably 25 μm to 55 μm. If the thickness of the adhesive layer is within this range, the above-mentioned desired T _PSA /T _PWR , T _PSA /T _OL and T _SP /T _PSA can be easily achieved.

F. Surface protection film

As described above, the surface protection film 50 typically has a substrate and an adhesive layer. Furthermore, in order to distinguish it from the adhesive layer 40, the adhesive layer of the surface protection film is sometimes referred to as a PF adhesive layer. The substrate can be made of any appropriate material. Specific examples of the constituent materials include: polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate polymers; (meth) acrylic polymers such as polymethyl methacrylate; cycloolefin polymers such as polynorbornene. These can be used alone or in combination of two or more.

The tensile modulus of elasticity of the substrate is preferably 1.0×10 ⁸ Pa to 1.0×10 ¹⁰ Pa, and more preferably 1.0×10 ⁹ Pa to 1.0×10 ¹⁰ Pa. If the tensile modulus of elasticity of the substrate is within this range, the effect of setting T _PSA /T _PWR , T _PSA /T _OL and T _SP /T _PSA to the above specific ranges becomes obvious. In addition, the tensile modulus of elasticity is measured in accordance with JIS K 7161.

Any appropriate composition can be used as the PF adhesive layer. Specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. An adhesive having properties that meet the desired target can be prepared by adjusting the type, amount, combination, and blending ratio of the monomers that form the base resin of the adhesive, as well as the blending amount of the crosslinking agent, the reaction temperature, the reaction time, etc. The base resin of the adhesive can be used alone or in combination of two or more. The base resin is preferably an acrylic resin (ie, the PF adhesive layer is preferably composed of an acrylic adhesive). The storage modulus of the PF adhesive layer at 25°C may be, for example, 1.0×10 ⁵ Pa to 1.0×10 ⁷ Pa.

The thickness of the surface protection film is preferably 30 μm to 80 μm, more preferably 40 μm to 60 μm. If the thickness of the surface protection film is within this range, the above-mentioned required T _PSA /T _OL can be easily achieved. Furthermore, the thickness of the surface protection film refers to the total thickness of the substrate and the PF adhesive layer.

G. Isolation parts

As the isolating member 60, any appropriate isolating member can be used. As a specific example, it can be exemplified as a plastic film, nonwoven fabric or paper with a surface coated with a stripping agent. As a specific example of a stripping agent, it can be exemplified as a silicone stripping agent, a fluorine stripping agent, and an acrylic long-chain alkyl ester stripping agent. As a specific example of a plastic film, it can be exemplified as a polyethylene terephthalate (PET) film, a polyethylene film, and a polypropylene film.

The thickness of the isolator is preferably 20 μm to 80 μm, more preferably 35 μm to 55 μm. When the thickness of the isolator is within this range, the above-mentioned required T _PSA /T _OL can be easily achieved.

H. Image display device

The optical multilayer body described in the above items A to G (substantially a polarizing plate with a phase difference layer) can be applied to an image display device. Therefore, an image display device including an optical multilayer body (substantially a polarizing plate with a phase difference layer) is also included in the embodiments of the present invention. The image display device typically includes an image display unit and a polarizing plate with a phase difference layer attached to the image display unit via an adhesive layer. As representative examples of image display devices, there can be cited liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices). In one embodiment, the image display device is an organic EL display device. In one embodiment, the image display device has a curved shape (essentially has a curved display screen) and/or is bendable or foldable. In such an image display device, the effect of the optical multilayer body (essentially a polarizing plate with a phase difference layer) of the embodiment of the present invention becomes obvious.

[Implementation example]

The present invention is specifically described below by way of examples, but the present invention is not limited to these examples. The measurement methods of various properties are as follows. Furthermore, unless otherwise specified, the "parts" and "%" in the examples and comparative examples are based on weight.

(1)Thickness

The thickness below 10μm was measured using an interferometer thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The thickness above 10μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name "KC-351C").

(2) Adhesive contamination

Use a cutting machine to cut the optical laminate obtained in the embodiment, comparative example and reference example into 100mm×50mm size. Observe the ends of the cut optical laminate visually and under an optical microscope to see if there is any contamination caused by the adhesive. Observe the 50 cut optical laminates in the same way and calculate the generation rate of adhesive contamination.

[Implementation Example 1]

1. Production of polarizing plates

As a thermoplastic resin substrate, a long strip of amorphous polyethylene terephthalate film (thickness: 100μm) with a Tg of about 75°C was used, and a single side of the resin substrate was subjected to a corona treatment.

13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA resin mixed with polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") at a ratio of 9:1, and the resulting mixture was dissolved in water to prepare a PVA aqueous solution (coating liquid).

The above-mentioned PVA aqueous solution is applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13μm to produce a laminate.

The obtained laminate was uniaxially stretched (in-air assisted stretching treatment) to 2.4 times in the longitudinal direction (length direction) in an oven at 130°C.

Next, the laminate was immersed in an insolubilizing bath (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilizing treatment).

Then, while adjusting the concentration so that the monomer transmittance (Ts) of the polarizing element finally obtained becomes the desired value, immerse it in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 relative to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds (dyeing treatment).

Then, immerse in a crosslinking bath (boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Afterwards, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4 wt%, potassium iodide concentration 5 wt%) at a liquid temperature of 70°C, and simultaneously uniaxially stretched (underwater stretching treatment) in the longitudinal direction (length direction) between rollers of different circumferential speeds at a total stretching ratio of 5.5 times.

Afterwards, the laminate is immersed in a cleaning bath at a liquid temperature of 20°C (an aqueous solution prepared by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).

Afterwards, it is dried in an oven maintained at about 90°C while being in contact with a SUS heating roller whose surface temperature is maintained at about 75°C (drying and shrinking treatment).

In this way, a polarizing element with a thickness of about 5μm is formed on the resin substrate, and a polarizing plate having a structure of resin substrate/polarizing element is obtained.

Furthermore, an acrylic film ("RV-20UB" manufactured by Toyo Kogyo Co., Ltd., thickness 20μm) as a protective substrate (protective layer) is bonded to the surface of the obtained polarizing element (the surface opposite to the resin substrate) via a UV-curing adhesive. Specifically, the curing adhesive is applied in such a way that the total thickness becomes about 1.0μm, and bonding is performed using a roller. Thereafter, UV rays are irradiated from the cycloolefin film side to cure the adhesive. Subsequently, the resin substrate is peeled off to obtain a polarizing plate having a cycloolefin film (protective layer)/polarizing element structure.

2. Preparation of the first phase difference layer and the second phase difference layer

10 g of polymerizable liquid crystal (manufactured by BASF: trade name "Paliocolor LC242", represented by the following formula) showing a nematic liquid crystal phase and 3 g of a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF: trade name "Irgacure 907") were dissolved in 40 g of toluene to prepare a liquid crystal composition (coating liquid).

Use a rubbing cloth to rub the surface of the polyethylene terephthalate (PET) film (thickness 38μm) to perform an alignment treatment. The direction of the alignment treatment is set to be 15° relative to the direction of the absorption axis of the polarizing element when attached to the polarizing plate when viewed from the side. The above-mentioned liquid crystal coating liquid is applied to the alignment-treated surface by a rod-type coating machine, and heated and dried at 90°C for 2 minutes to align the liquid crystal compound. Use a metal halogen lamp to irradiate the liquid crystal layer formed by the above method with 1mJ/ ^cm2 of light to harden the liquid crystal layer, thereby forming a liquid crystal alignment cured layer A on the PET film. The thickness of the liquid crystal alignment cured layer A is 2μm, and the in-plane phase difference Re(550) is 270nm. Furthermore, the liquid crystal alignment cured layer A has a refractive index distribution of nx>ny=nz. The liquid crystal alignment cured layer A is used as the first phase difference layer.

The coating thickness is changed, and the orientation treatment direction is set to be 75° relative to the absorption axis of the polarizing element when viewed from the side. In addition, a liquid crystal orientation curing layer B is formed on the PET film in the same manner as above. The thickness of the liquid crystal orientation curing layer B is 1μm, and the in-plane phase difference Re(550) is 140nm. Furthermore, the liquid crystal orientation curing layer B has a refractive index distribution of nx>ny=nz. The liquid crystal orientation curing layer B is used as the second phase difference layer.

3. Production of polarizing plate with phase difference layer

The liquid crystal alignment cured layer A (first phase difference layer) and the liquid crystal alignment cured layer B (second phase difference layer) obtained in 2. above are sequentially transferred to the surface of the polarizing element of the polarizing plate obtained in 1. At this time, the transfer (lamination) is performed in such a manner that the angle formed by the absorption axis of the polarizing element and the retarded axis of the alignment cured layer A is 15°, and the angle formed by the absorption axis of the polarizing element and the retarded axis of the alignment cured layer B is 75°. Furthermore, each transfer (lamination) is performed through an ultraviolet curing adhesive (thickness 1.0μm). Finally, an acrylic adhesive layer (thickness T _PSA : 25μm) is arranged on the surface of the alignment cured layer B (second phase difference layer). Thus, a polarizing plate with a phase difference layer having a structure of protective layer/adhesive/polarizing element/first adhesive layer/first phase difference layer/second adhesive layer/second phase difference layer/adhesive layer is obtained. The thickness T _PWR of the polarizing plate with a phase difference layer is 56 μm.

4. Fabrication of optical multilayers

A surface protection film (thickness 48 μm) was bonded to the protective layer surface of the polarizing plate with phase difference layer obtained in 3. above, and a spacer (thickness T _SP : 38 μm) was bonded to the adhesive layer surface to obtain an optical laminate. The thickness T _OL of the obtained optical laminate was 142 μm. The obtained optical laminate was subjected to the evaluation in (2) above. The results are shown in Table 1.

[Example 2]

A polarizing plate with a phase difference layer was produced in the same manner as in Example 1 except that the thickness T _PSA of the adhesive layer was set to 50 μm. An optical laminate was produced in the same manner as in Example 1 except that the T _SP of the spacer was set to 50 μm using the polarizing plate with a phase difference layer. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Implementation Example 3]

A polarizing plate with a phase difference layer was produced in the same manner as in Example 1. An optical laminate was produced in the same manner as in Example 1 except that _{the TSP} of the spacer was set to 50 μm. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparison Example 1]

A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1 except that the thickness T _PSA of the adhesive layer was set to 50 μm. An optical laminate was prepared in the same manner as in Example 1 except that the polarizing plate with a phase difference layer was used. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Reference Example 1]

A polarizing plate with a phase difference layer was prepared in the same manner as in Example 1 except that a 27 μm thick HC-COP film was used as a protective layer and the thickness of the adhesive layer T _PSA was set to 15 μm. Furthermore, the HC-COP film is a film having a 2 μm thick hard coat (HC) layer formed on a 25 μm thick cycloolefin resin (COP) film, and the HC layer was bonded to the viewing side. An optical laminate was prepared in the same manner as in Example 1 except that the polarizing plate with a phase difference layer was used. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Reference Example 2]

A polarizing plate with a phase difference layer was prepared in the same manner as in Example 2 except that a 27 μm thick HC-COP film was used as a protective layer and the thickness of the adhesive layer T _PSA was set to 15 μm. The HC-COP film is a film having a 2 μm thick hard coat (HC) layer formed on a 25 μm thick cycloolefin resin (COP) film, and the HC layer was bonded to the viewing side. An optical laminate was prepared in the same manner as in Example 1 except that the polarizing plate with a phase difference layer was used. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Reference Example 3]

A 30μm thick PVA resin film strip was stretched uniaxially in the strip direction by a roller stretching machine at a total stretching ratio of 6.0 times, and swelling, dyeing, crosslinking and washing were performed at the same time, and finally drying was performed to produce a 12μm thick polarizing element. A COP-HC film was bonded to one side of the obtained polarizing element as a visual side protective layer via a PVA adhesive (1μm thick). Furthermore, the COP-HC film is a 25μm thick cycloolefin resin (COP) film with a 7μm thick hard coating (HC) layer formed thereon, and the HC layer was bonded to the visual side. Furthermore, a triacetyl cellulose (TAC) film (thickness 25 μm) was bonded to the other side of the polarizing element via a _PVA -based adhesive to obtain a polarizing plate having a structure of protective layer (COP-HC film)/polarizing element/protective layer (TAC film). Hereinafter, a polarizing plate with a phase difference layer having a structure of a viewing side protective layer/adhesive/polarizing element/adhesive/protective layer/first adhesive layer/first phase difference layer/second adhesive layer/second phase difference layer/adhesive layer was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer T PSA was set to 30 μm. The thickness T _PWR of the obtained polarizing plate with a phase difference layer was 105 μm. An optical laminate was prepared in the same manner as in Example 1 except that the polarizing plate with a phase difference layer was used. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Reference Example 4]

A polarizing plate with a phase difference layer was prepared in the same manner as in Reference Example 3. An optical laminate was prepared in the same manner as in Example 1 except that the polarizing plate with a phase difference layer was used and the _TSP of the spacer was set to 50 μm. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[evaluate]

As shown in Table 1, according to the embodiment of the present invention, by setting the T _PSA /T _OL of the polarizing plate with a phase difference layer having a T _PSA /T _PWR of 0.4 or more to a specific value or below, or by setting the T _SP /T _PSA to a specific value or more, the adhesive contamination when the polarizing plate with a phase difference layer is cut is significantly suppressed. Furthermore, by comparing Example 2 with Comparative Example 1, it can be seen that when T _PSA /T _OL is about 0.3, 100% of the adhesive contamination occurs, while when T _PSA /T _OL is about 0.28, the adhesive contamination rate drops sharply to 20%. That is, it can be seen that T _PSA /T _OL has a critical value near 0.29. In addition, according to the reference example, no adhesive contamination occurs in the polarizing plate with a phase difference layer having a T _PSA /T _PWR less than 0.4, while adhesive contamination is a new issue for the polarizing plate with a phase difference layer having a T _PSA /T _PWR greater than 0.4.

[Industrial availability]

The polarizing plate with phase difference layer obtained from the optical multilayer of the present invention is suitable for use as a circular polarizing plate for liquid crystal display devices, organic EL display devices and inorganic EL display devices.

10: Polarizing plate

11: Polarizing element

12: Protective layer

21: 1st phase difference layer

22: Second phase difference layer

31: 1st subsequent agent layer

32: Second subsequent agent layer

40: Adhesive layer

50: Surface protection film

60: Isolation parts

70: Polarizing plate with phase difference layer

100: Optical multilayers

Claims (12)

An optical laminate, comprising: a polarizing plate with a phase difference layer, comprising: a polarizing plate including a polarizing element and a protective layer at least on a viewing side of the polarizing element, a first phase difference layer bonded to a side opposite to the viewing side of the polarizing plate via a first adhesive layer, a second phase difference layer bonded to the first phase difference layer via a second adhesive layer , and an adhesive layer arranged on the side of the second phase difference layer opposite to the first phase difference layer; a surface protection film, which is temporarily adhered to the viewing side of the polarizing plate with the phase difference layer in a removable manner; and a spacer, which is temporarily adhered to the adhesive layer of the polarizing plate with the phase difference layer in a removable manner; when the thickness of the adhesive layer is set to T _PSA , the thickness of the polarizing plate with the phase difference layer is set to T _PWR , and the thickness of the optical laminate is set to T _OL , the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4 T _PSA /T _OL ≦0.29. An optical laminate, comprising: a polarizing plate with a phase difference layer, comprising: a polarizing plate including a polarizing element and a protective layer at least on a viewing side of the polarizing element, a first phase difference layer bonded to a side opposite to the viewing side of the polarizing plate via a first adhesive layer, a second phase difference layer bonded to the first phase difference layer via a second adhesive layer , and an adhesive layer arranged on the side of the second phase difference layer opposite to the first phase difference layer; a surface protection film, which is temporarily adhered to the viewing side of the polarizing plate with the phase difference layer in a removable manner; and a spacer, which is temporarily adhered to the adhesive layer of the polarizing plate with the phase difference layer in a removable manner; when the thickness of the adhesive layer is set to T _PSA , the thickness of the polarizing plate with the phase difference layer is set to T _PWR , and the thickness of the spacer is set to T _SP , the optical laminate satisfies the following relationship: T _PSA /T _PWR ≧0.4 T _SP /T _PSA ≧0.8. In the optical laminate of claim 1, when the thickness of the isolation element is set to T _SP , the T _PSA , the T _PWR and the T _SP satisfy the following relationship: T _PSA /T _PWR ≧0.4 T _SP /T _PSA ≧0.8. The optical laminate of any one of claims 1 to 3, wherein the thickness T _PSA of the adhesive layer is greater than 20 μm. An optical multilayer as claimed in any one of claims 1 to 3, wherein the thickness of the polarizing element is less than 8 μm. The optical laminate of any one of claims 1 to 3, wherein the storage modulus of the adhesive layer at 25°C is 1.0×10 ⁴ Pa to 1.0×10 ⁶ Pa. The optical laminate of any one of claims 1 to 3, wherein the thickness T _PWR of the polarizing plate with phase difference layer is less than 100 μm. An optical laminate as claimed in any one of claims 1 to 3, wherein the polarizing plate has a protective layer only on the viewing side of the polarizing element. An optical multilayer as claimed in any one of claims 1 to 3, wherein the first phase difference layer and the second phase difference layer are alignment solidified layers of liquid crystal compounds, respectively. The optical multilayer of claim 9, wherein the Re(550) of the first phase difference layer is 200nm~300nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element is 10°~20°, and the Re(550) of the second phase difference layer is 100nm~190nm, and the angle formed by its retardation axis and the absorption axis of the polarizing element is 70°~80°. An image display device having the above-mentioned polarizing plate with phase difference layer of the optical multilayer body as claimed in any one of claims 1 to 10. The image display device of claim 11 is an organic electroluminescent display device.