WO2025069656A1 - Laminate and display device - Google Patents

Abstract

The present invention addresses the problem of providing a laminate and a display device which each have both light resistance and impact resistance.　A laminate according to the present invention comprises resin layers, cured layers, and an adhesive layer, said laminate being characterized in that: a first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer are laminated in this order; the first resin layer contains a dye compound that has a maximum absorption wavelength in the range of 360-379 nm in an ultraviolet visible light absorption spectrum of a wavelength region of 300-460 nm; the average light transmittance of the first resin layer in the wavelength region of 450-800 nm is not less than 87%; the storage modulus of the first resin layer is in the range of 4.0-8.0 GPa at 25°C; and the value of the ratio of the storage modulus of the second resin layer to the storage modulus of the first resin layer is in the range of 0.7-1.5 at 25°C.

Description

Laminate and display device

The present invention relates to a laminate and a display device. More specifically, the present invention relates to a laminate and a display device that combines light resistance and impact resistance.

Recently, there has been active development of flexible displays that can be folded or rolled up. Flexible displays consist of a display component and a cover component that protects the display component.

In flexible displays, the substrate used for the cover member is required to have flexibility. Therefore, it has been considered to change the conventionally used glass substrate to a resin substrate or to make the glass substrate itself thinner. Among them, thin-film glass (Ultra Thin Glass: UTG) has become mainstream as a substrate from the viewpoint of luxury and resistance to folding (durability).
However, since thin film glass is vulnerable to impact and easily breaks, a technique is known in which a protective film is attached to the thin film glass to improve impact resistance when used as a cover member.

Patent Document 1 discloses a technology for improving the impact resistance of a cover member, in which a laminate in which a cured layer is laminated on a protective film is used as the cover member. However, the demand for impact resistance continues to increase, leaving room for improvement.

There is also technology to increase the thickness of the laminate used as a cover member in order to improve impact resistance. However, there is a problem in that increasing the thickness of the laminate reduces the flexibility of the laminate, and with this technology it is difficult to achieve both impact resistance and flexibility of the laminate. Furthermore, this technology goes against the trend toward thinner flexible displays.

On the other hand, since many flexible displays are used in mobile devices, they need to be durable enough for outdoor use, especially light resistance.

Patent Document 2 discloses a technology for achieving both light resistance and impact resistance in a display device, in which a cover member is made of an adhesive layer containing a (meth)acrylic polymer of a specific composition and an ultraviolet absorber.

Patent Document 3 also discloses a technology for improving the light resistance of display devices, in which a highly transparent optical film with excellent blocking properties for ultraviolet light and the short wavelength region of visible light is used as a cover member. However, the demand for impact resistance continues to increase, and there is room for improvement in achieving both light resistance and impact resistance.

Korean Patent Publication No. 10-2020-0072643 JP 2020-139108 A JP 2017-187619 A

The present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a laminate and a display device that combine light resistance and impact resistance.

In order to solve the above-mentioned problems, the present inventors have investigated the causes of the above-mentioned problems, and as a result, have discovered that in a laminate having a resin layer, a cured layer, and an adhesive layer, when the resin layer contains a dye compound having ultraviolet absorbing ability, and the light transmittance in the visible light region of the resin layer is each within a specific range, and the storage modulus of the resin layer is also within a specific range, both of which can achieve both light resistance and impact resistance, thereby arriving at the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

1. A laminate having a resin layer, a cured layer, and an adhesive layer,
A first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer are laminated in this order,
the first resin layer contains a dye compound having a maximum absorption wavelength in the range of 360 to 379 nm in an ultraviolet-visible light absorption spectrum in a wavelength region of 300 to 460 nm,
The first resin layer has an average light transmittance of 87% or more in a wavelength range of 450 to 800 nm;
The storage modulus of the first resin layer at 25° C. is within a range of 4.0 to 8.0 GPa,
a ratio of a storage modulus at 25° C. of the second resin layer to that of the first resin layer is within a range of 0.7 to 1.5.

2. The laminate according to item 1, wherein the first resin layer contains a cellulose ester.

3. The laminate according to item 1, wherein the dye compound has a structure represented by the following general formula (1):

(In the formula, R ₁₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an amino group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group. R ₁₂ represents a hydrogen atom or a hydroxy group.)

4. The laminate according to item 1, wherein the dye compound has a structure represented by the following general formula (2):

(In the formula, R ₂₁ represents a hydrogen atom or a hydroxy group. R ₂₂ , R ₂₃ , and R ₂₄ represent an alkyl group, an alkoxy group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group.)

5. The laminate according to item 1, wherein the first resin layer has a thickness in the range of 15 to 50 μm.

6. The laminate according to item 1, wherein the second resin layer has a storage modulus at 25° C. in the range of 4.0 to 8.0 GPa.

7. Further comprising a glass layer,
7. The laminate according to any one of claims 1 to 6, wherein the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, and the glass layer are laminated in this order.

8. Further comprising a second adhesive layer;
The laminate described in claim 7, characterized in that the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, the second adhesive layer, and the glass layer are laminated in this order.

9. The laminate according to item 7, wherein the thickness of the glass layer is within a range of 10 to 30 μm.

10. Further comprising a third adhesive layer;
The laminate described in item 8, characterized in that the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, the second adhesive layer, the glass layer, and the third adhesive layer are laminated in this order.

11. A display device comprising the laminate according to claim 10.

12. The display device according to item 11, wherein the first resin layer of the laminate is disposed closer to a viewing side of the display device than the second resin layer.

The above-mentioned means of the present invention make it possible to provide a laminate and a display device that combine light resistance and impact resistance.

The mechanism by which the effects of this invention are expressed or acted upon is not clear, but is speculated as follows.

When thin film glass is used as the cover member, it is preferable that the cover member has a member that protects the thin film glass. As described above, when a cover member that includes thin film glass and a member that protects the thin film glass is attached to a display device, the display device is required to have both light resistance and impact resistance. In addition, in view of the increasing demand for thinner display devices, the member that protects the thin film glass is required to be flexible and thin.

The laminate of the present invention as a member for protecting thin glass, i.e., a glass protection film, is formed by laminating a first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer in this order.
By having the hardened layer in the laminate, the impact resistance of the display device when the laminate is attached can be improved. Also, by dividing the hardened layer into two layers, it is considered that the impact resistance of the display device when the laminate is attached can be maintained while also improving the flexibility.

Furthermore, it is believed that the laminate having a resin layer can improve the light resistance and flexibility of the display device when the laminate is attached.

Specifically, the first resin layer contains a dye compound whose maximum absorption wavelength is in the range of 360 to 379 nm in the absorption spectrum of the wavelength region of 300 to 460 nm. In other words, the first resin layer is endowed with the property of absorbing ultraviolet rays. This makes it possible to protect the display device from ultraviolet rays and improve the light resistance of the display device when the laminate is attached.

The average light transmittance of the first resin layer in the wavelength range of 450 to 800 nm is set to 87% or more, that is, the first resin layer is given the property of transmitting visible light. This makes it possible to prevent the light emitted from the light-emitting element or light-emitting device in the display device from being absorbed by the resin layer, and to increase the amount of visible light emission. In other words, it is possible to reduce light emission loss.

Furthermore, by setting the storage modulus of the first resin layer within a specific range, that is, by arranging a resin layer that is softer than the cured layer, the impact resistance of the laminate can be improved. Furthermore, the ratio of the storage modulus of the second resin layer to the first resin layer is set within a specific range. In other words, the storage modulus of the first resin layer and the storage modulus of the second resin layer are set to be approximately the same. This can further improve the flexibility of the laminate.

Furthermore, a resin layer with high flexibility is placed near the cured layer, that is, the first resin layer is placed near the first cured layer, and the second resin layer is placed near the second cured layer. This allows each cured layer to bend following the resin layer, which is thought to improve the flexibility of the entire laminate.

Cross-sectional view of the basic layer structure of a laminate Cross-sectional view of a basic layer structure of a laminate having a glass layer Cross-sectional view of a basic layer structure of a laminate having a glass layer Schematic diagram showing an example of a method for producing thin glass Application example to an organic EL display, which is an example of a display device

The laminate of the present invention is a laminate having a resin layer, a cured layer, and an adhesive layer. The laminate of the present invention is laminated in the order of a first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer. The first resin layer contains a dye compound having a maximum absorption wavelength in a range of 360 to 379 nm in an ultraviolet-visible light absorption spectrum of a wavelength region of 300 to 460 nm. The average light transmittance of the first resin layer in a wavelength region of 450 to 800 nm is 87% or more. The storage modulus of the first resin layer at 25° C. is in the range of 4.0 to 8.0 GPa. The ratio of the storage modulus of the second resin layer at 25° C. to that of the first resin layer is in the range of 0.7 to 1.5. The laminate is characterized by the above.
This feature is a technical feature common to or corresponding to the following embodiments.

In one embodiment of the present invention, the first resin layer preferably contains a cellulose ester, from the viewpoints of making it easy to add additives to the resin and adjusting the light transmittance and storage modulus of the resin layer to desired values.

In one embodiment of the present invention, from the viewpoint of being able to adjust the light transmittance of the resin layer to a desired value, it is preferable that the dye compound has a structure represented by the above general formula (1).

In an embodiment of the present invention, from the viewpoint of being able to adjust the light transmittance of the resin layer to a desired value, it is preferable that the dye compound has a structure represented by the above general formula (2).

In one embodiment of the present invention, the thickness of the first resin layer is preferably within the range of 15 to 50 μm, from the viewpoint of being able to adjust the light transmittance and storage modulus of the resin layer to desired values and obtaining flexibility.

In one embodiment of the present invention, from the viewpoint of obtaining impact resistance, it is preferable that the storage modulus of the second resin layer at 25°C is within the range of 4.0 to 8.0 GPa.

In an embodiment of the present invention, from the viewpoint of having a cover member with a glass layer, it is preferable that the cover member further has a glass layer, and is laminated in the following order: the first hardened layer, the first resin layer, the first adhesive layer, the second hardened layer, the second resin layer, and the glass layer.

In an embodiment of the present invention, from the viewpoint of attaching a glass layer, it is preferable that the second adhesive layer is further included, and the first hardened layer, the first resin layer, the first adhesive layer, the second hardened layer, the second resin layer, the second adhesive layer, and the glass layer are laminated in this order.

In one embodiment of the present invention, from the viewpoint of making the cover member thinner, it is preferable that the thickness of the glass layer is within the range of 10 to 30 μm.

In an embodiment of the present invention, from the viewpoint of attachment to a display device, it is preferable that the laminate further includes a third adhesive layer, and is laminated in the following order: the first hardened layer, the first resin layer, the first adhesive layer, the second hardened layer, the second resin layer, the second adhesive layer, the glass layer, and the third adhesive layer.

The display device of the present invention is characterized by comprising the laminate.

In an embodiment of the present invention, from the viewpoint of achieving a significant effect, it is preferable that the first resin layer of the laminate is disposed closer to the viewing side of the display device than the second resin layer.

The present invention, its components, and the forms and modes for implementing the present invention are described in detail below. Note that in this application, "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

1. Overview of the Laminate The laminate of the present invention is a laminate having a resin layer, a cured layer, and an adhesive layer. The laminate of the present invention is a laminate in which a first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer are laminated in this order. The first resin layer contains a dye compound whose maximum absorption wavelength is present in a range of 360 to 379 nm in an ultraviolet-visible light absorption spectrum of a wavelength region of 300 to 460 nm. The first resin layer has an average light transmittance of 87% or more in a wavelength region of 450 to 800 nm. The first resin layer has a storage modulus at 25° C. in a range of 4.0 to 8.0 GPa. The ratio of the storage modulus at 25° C. of the second resin layer to that of the first resin layer is in a range of 0.7 to 1.5. The laminate is characterized by the above.

The laminate of the present invention is used as a protective member for thin-film glass (protective film for glass). It is preferable that the laminate of the present invention is attached to thin-film glass and used as a cover member for a display device. In addition to the resin layer, cured layer, and adhesive layer, the laminate may have other layers as necessary.

FIG. 1 is a cross-sectional view of the basic layer structure of a laminate. The laminate 10 is formed by laminating a first cured layer 1, a first resin layer 2, a first adhesive layer 3, a second cured layer 4, and a second resin layer 5 in this order. The first cured layer 1 and the second cured layer 4 may be of the same material and physical properties, or may be of different materials and physical properties. Furthermore, the first resin layer 2 and the second resin layer 5 may be of the same material and physical properties, or may be of different materials and physical properties, as long as they satisfy the storage modulus conditions.

The laminate 10 has a first adhesive layer 3 between the first resin layer 2 and the second cured layer 4. If necessary, an adhesive layer may be further provided between the first cured layer 1 and the first resin layer 2, or between the second cured layer 4 and the second resin layer 5.

Figures 2 and 3 are cross-sectional views of the basic layer structure of a laminate having a glass layer. As shown in Figure 2, the laminate 11 may further have a glass layer 6 on the side of the second resin layer 5 opposite the second cured layer 4. Also, as shown in Figure 3, the laminate 12 may have a second adhesive layer between the second resin layer 5 and the glass layer 6. The second adhesive layer may be of the same material and physical properties as the first adhesive layer, or may be of a different material and physical properties.

From the viewpoint of storage modulus, it is preferable that the first resin layer and the second resin layer have similar characteristics. On the other hand, from the viewpoint of light transmittance, the first resin layer and the second resin layer do not necessarily have to have similar characteristics. In other words, there are no particular restrictions on the light transmittance of the second resin layer.

2. Structure of the Laminate The laminate of the present invention has a cured layer, a resin layer, and an adhesive layer. It may further have a glass layer. The cured layer, the resin layer, the adhesive layer, and the glass layer will be described below.

(1) Hardened layer The laminate of the present invention has a hardened layer, which can improve the impact resistance of a display device when the laminate is attached. In addition, by dividing the hardened layer into two layers, it is considered that the flexibility of the display device when the laminate is attached can be improved while maintaining the impact resistance.

In the present invention, the term "cured layer" refers to a layer formed by curing a resin by heating or irradiating it with active energy rays. It is preferable that the cured layer exhibits a hardness of "HB" or higher in the pencil hardness test specified in JIS K5600-2014.

As mentioned above, the first and second hardened layers may be made of the same material and have the same physical properties, or may be made of different materials and have different physical properties.

From the standpoint of mechanical strength such as scratch resistance and pencil hardness, the thickness of the cured layer is preferably within the range of 0.01 to 20 μm, and more preferably within the range of 0.5 to 10 μm.

The cured layer may be made of the same material as the adhesive layer described below. However, the cured layer satisfies the above hardness conditions and does not have adhesive properties. Specifically, the cured layer does not have sufficient adhesive properties to attach the laminate to a display device or to bond the layers in the laminate together.

(1.1) Constituent Materials of the Cured Layer The resin and other additives contained in the cured layer will be described below.

(1.1.1) Resin There are no particular limitations on the resin, so long as it is a curable resin that is cured by heating or irradiation with active energy rays. Among them, active energy ray curable resins are preferred from the viewpoint of curing at room temperature in a short time. In addition, the active energy ray curable resin is preferably a resin containing a monomer having an ethylenically unsaturated double bond.

Examples of active energy rays include ultraviolet rays and electron beams. Among them, from the viewpoint of mechanical strength such as scratch resistance, impact resistance, and pencil hardness, it is preferable that the active energy rays be ultraviolet rays.

The active energy ray curable resin is preferably an acrylic material.
Examples of acrylic materials include monofunctional or polyfunctional (meth)acrylate compounds such as (meth)acrylic acid esters of polyhydric alcohols, and polyfunctional urethane (meth)acrylate compounds synthesized from diisocyanates, polyhydric alcohols, and hydroxy esters of (meth)acrylic acid, etc. In addition to these, examples of the material include polyethers, polyesters, epoxy resins, alkyd resins, spiroacetal resins, polybutadienes, and polyene-polythiol resins having acrylate functional groups.

Among these resins, those that are cured by ultraviolet light are more preferable. For example, ultraviolet-curable acrylate resins, ultraviolet-curable urethane acrylate resins, ultraviolet-curable polyester acrylates, ultraviolet-curable epoxy acrylate resins, ultraviolet-curable polyol acrylates, ultraviolet-curable epoxy resins, etc. are preferable. Among these, ultraviolet-curable acrylate resins are preferable.

The cured layer is formed, for example, using a composition for forming a cured layer that contains an active energy ray-curable resin, a polymerization initiator, and a solvent. The solvent contained in the composition for forming a cured layer is preferably a solvent that dissolves or swells the resin layer. By dissolving or swelling the resin layer with the solvent, the composition for forming a cured layer can easily penetrate from the surface of the resin layer to the inside, improving the adhesion between the resin layer and the cured layer.

(1.1.2) Other Additives From the viewpoint of increasing hardness, suppressing curing shrinkage, preventing blocking, controlling the refractive index, imparting anti-glare properties, controlling the properties of the cured layer surface, etc., the cured layer may contain conventionally known fine particles, dispersants, antistatic agents, silane coupling agents, thickeners, coloring inhibitors, colorants (pigments or dyes), defoamers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, surface modifiers, etc. In addition, the cured layer may contain a photosensitizer. Examples of photosensitizers include n-butylamine, triethylamine, and poly-n-butylphosphine.

From the viewpoint of suppressing dimensional fluctuation, it is preferable that the cured layer contains fine particles. The content of the fine particles is preferably within the range of 100 to 400% based on the total mass of the active energy ray curable resin. Although there are no particular limitations, the fine particles are preferably fine particles composed of a metal oxide. Hereinafter, fine particles composed of a metal oxide are also referred to as "metal oxide particles".

Examples of metal oxides include silica, alumina, zirconia, titanium oxide, and antimony pentoxide. Of these, it is preferable that the metal oxide particles are composed of silica. The silica microparticles may be hollow particles with cavities formed inside.

The fine particles are preferably coated with a polymeric silane coupling agent. By coating the surfaces of the fine particles with a polymeric silane coupling agent, the fine particles can be uniformly dispersed in the composition for forming the cured layer. The average particle size of the fine particles coated with the polymeric silane coupling agent is preferably within the range of 5 to 500 nm, and more preferably within the range of 10 to 200 nm. By being within the above range, the optical properties of the cured layer can be improved.

The polymeric silane coupling agent is prepared by reacting a polymerizable monomer with a silane coupling agent (reactive silane compound). The polymerizable monomer may be a monomer having an ethylenically unsaturated double bond, and among these, a monomer selected from (meth)acrylic acid and its derivatives is preferable. The reactive silane compound is preferably a hydrolyzable silane compound in which three alkoxy groups and one functional group are bonded to a silicon atom. Examples of functional groups bonded to silicon atoms include (meth)acryloxy groups, epoxy groups (glycidyl groups), urethane groups, amino groups, fluoro groups, and mercapto groups.

The polymeric silane coupling agent can be synthesized, for example, in accordance with the method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in JP-A-11-116240. The number average molecular weight of the polymeric silane coupling agent is preferably in the range of 2,500 to 150,000, and more preferably in the range of 2,000 to 100,000, calculated as polystyrene.

The method of coating the surface of fine particles with a polymeric silane coupling agent will be explained using silica fine particles as an example. First, a dispersion liquid is prepared by dispersing silica fine particles and a polymeric silane coupling agent in an organic solvent. An alkali is added to this dispersion liquid to generate OH groups on the surface of the silica fine particles. The polymeric silane coupling agent is adsorbed to the OH groups. Alternatively, the OH groups are bonded to the OH groups of the polymeric silane coupling agent by a dehydration reaction. Finally, the silica fine particles to which the polymeric silane coupling agent is adsorbed or bonded are separated from the dispersion liquid and dried. This results in silica fine particles coated with the polymeric silane coupling agent.

(1.2) Method for Producing Cured Layer The method for preparing the composition for forming the cured layer is not particularly limited as long as it is a method that can uniformly mix the solid components contained in the cured layer with the solvent. For example, the composition for forming the cured layer can be prepared by mixing or dissolving each of the solid components and the solvent using a known device such as a paint shaker, a bead mill, a kneader, or a mixer.

The cured layer can be formed, for example, by applying a composition for forming a cured layer to the surface of a resin layer and curing the active energy ray-curable resin in the coating. There are no particular limitations on the method for applying the composition for forming a cured layer, and any conventionally known method can be used.

The coating method is preferably, for example, a microgravure coating method from the viewpoint of forming a uniform thin layer. Also, from the viewpoint of forming a thick layer, a die coating method is preferable. After removing the solvent from the coating film as necessary, the coating film is irradiated with active energy rays to cure the active energy ray curable resin, thereby obtaining a cured layer.

The cured layer does not necessarily have to be formed directly on the surface of the resin layer. The cured layer may be formed on a support, and after peeling the cured layer from the support, the resin layer and the cured layer may be bonded together via an adhesive layer.

(2) Resin Layer The first resin layer according to the present invention contains a dye compound having a maximum absorption wavelength in the range of 360 to 379 nm in the ultraviolet-visible light absorption spectrum in the wavelength region of 300 to 460 nm. The average light transmittance of the first resin layer according to the present invention in the wavelength region of 450 to 800 nm (visible light region) is 87% or more. The first resin layer according to the present invention also has a storage modulus at 25° C. in the range of 4.0 to 8.0 GPa. Furthermore, the ratio of the storage modulus at 25° C. of the second resin layer according to the present invention to that of the first resin layer is in the range of 0.7 to 1.5.

The laminate of the present invention has a resin layer, which is believed to improve the light resistance and flexibility of the display device when the laminate is attached. In addition, the first resin layer is disposed near the first cured layer, and the second resin layer is disposed near the second cured layer. This allows each cured layer to bend following the resin layer, which is believed to improve the flexibility of the laminate as a whole.

In the present invention, the "resin layer" refers to a layer that contains a resin as a main component and does not correspond to the above-mentioned cured layer or the adhesive layer described below.
The first resin layer and the second resin layer may be made of the same material and have the same physical properties, or may be made of different materials and have different physical properties, so long as they satisfy the conditions of light transmittance and storage modulus.

The light transmittance of the resin layer can be adjusted by incorporating dyes or the like into the resin layer. The storage modulus of the resin layer can be adjusted by incorporating plasticizers, particles (rubber particles, metal oxide particles, etc.), fibers (acicular particles, cellulose nanofibers, etc.) into the resin layer. Conventional plasticizers, particles, and fibers can be used. The storage modulus of the resin layer can also be adjusted by the production conditions of the resin layer.

(2.1) Constituent Materials of Resin Layer Hereinafter, the film-forming components contained in the resin layer, such as the resin, dye compound, plasticizer, rubber particles, UV absorber, antioxidant, fine particles, and other additives, will be described.

(2.1.1) Resin The resin contained in the resin layer as a film-forming component is preferably a thermoplastic resin material, and is not limited as long as it can be handled as a film after film formation. For example, examples of thermoplastic resins include cellulose esters such as triacetyl cellulose (TAC), cellulose acetate propionate (CAP), and diacetyl cellulose (DAC); (meth)acrylic resins such as polymethyl methacrylate (PMMA) and styrene-(meth)acrylate copolymers; cyclic olefin resins such as cycloolefin resins (COP); and polyesters such as polyethylene terephthalate (PET).

Among them, the resin is preferably a cellulose ester, since it is easy for a network to form between molecules and it can impart rigidity to the resin layer. In addition, pigments, plasticizers, particles, fibers, etc. can be added to the cellulose ester.

(2.1.1.1) Cellulose ester Cellulose is a polymer in which β-glucose units are linked in a linear chain via β-1,4-glycosidic bonds. Cellulose ester is cellulose in which some or all of the hydrogen atoms in the hydroxyl groups (-OH) at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups.

The cellulose ester is not particularly limited, but is preferably an ester of a linear or branched carboxylic acid having about 2 to 22 carbon atoms.
Examples of the carboxylic acid constituting the ester include an aliphatic carboxylic acid, an alicyclic carboxylic acid, and an aromatic carboxylic acid.

Examples of the substituted acyl groups of cellulose esters include acyl groups having 2 to 22 carbon atoms, such as acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl, lauroyl, and stearoyl.

The carboxylic acid (acyl group) constituting the ester may have a substituent.
The carboxylic acid constituting the ester is preferably a lower fatty acid having 6 or less carbon atoms, and more preferably a lower fatty acid having 3 or less carbon atoms.

The acyl group in the cellulose ester may be of a single type or a combination of multiple acyl groups.

Specific examples of cellulose esters include cellulose acetates such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), as well as mixed fatty acid esters of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group, such as cellulose acetate propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate.
The cellulose ester may be contained alone or in combination of two or more kinds.

<Type and Substitution Degree of Acyl Group>
By appropriately selecting the type and substitution degree of the acyl group of the cellulose ester, the humidity change of the retardation in the resin layer can be controlled within a desired range, and as a result, the uniformity of the thickness of the resin layer can be improved.

The degree of acyl substitution represents the average number of acyl groups per glucose unit, i.e., how many of the hydrogen atoms in the hydroxyl groups at the 2-, 3-, and 6-positions in one glucose unit are substituted with acyl groups.
Therefore, the maximum degree of substitution of the acyl group is 3.0, which means that all of the hydrogen atoms of the hydroxy groups at the 2-, 3- and 6-positions are substituted with acyl groups.

The acyl groups may be substituted evenly at the 2-, 3- and 6-positions of one glucose unit, or may be substituted with a distribution.
The degree of acyl substitution can be determined by the method specified in ASTM-D817-96.

If the substitution degree of the acyl group of the cellulose ester is too large, the retardation is difficult to be expressed, so it is necessary to increase the stretching ratio when preparing the resin layer. However, it is difficult to uniformly stretch at a high stretching ratio, and the thickness of the resin layer is likely to vary greatly. On the other hand, the smaller the substitution degree of the acyl group of the cellulose ester, the easier it is to express the retardation, so the thickness of the resin layer can be made thin and uniform.
However, if the degree of substitution of the acyl group in the cellulose ester is too small, the durability of the resin layer decreases, and therefore, from the viewpoint of durability, it is preferable not to make the degree of substitution too small.

The humidity-dependent change in retardation (Rt, phase difference) in the thickness direction occurs when water molecules coordinate with the carbonyl groups of cellulose. Therefore, the smaller the degree of acyl group substitution, i.e., the fewer the carbonyl groups in the cellulose, the less humidity-dependent change in Rt occurs.

The degree of substitution of the acyl group in the cellulose ester is preferably within the range of 2.1 to 3.0.
By being in the above range, environmental fluctuations (particularly fluctuations in Rt due to humidity) can be suppressed, and the uniformity of the thickness of the resin layer can be improved. In addition, the flowability and stretchability during the production of the resin layer can be improved.

In addition, it is preferable that the degree of substitution of the acyl group of the cellulose ester satisfies both of the following formulas (a) and (b). In the following formulas (a) and (b), X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or the butyryl group, or the degree of substitution of a mixture thereof.

Formula (a): 2.1≦X+Y≦2.5
Formula (b): 0≦Y≦1.5

The cellulose ester is preferably cellulose acetate (Y=0) or cellulose acetate propionate (CAP) (Y: propionyl group, Y>0). Of these, cellulose acetate with Y=0 is preferred from the viewpoint of uniformity of the thickness of the resin layer.

From the viewpoints of retardation expression, variation in Rt due to humidity, and uniformity of the resin layer, it is preferable that the degree of substitution X of the acetyl group of cellulose acetate satisfies 2.1≦X≦3.0. Examples of cellulose acetate that satisfies the above range include cellulose diacetate (DAC) and cellulose triacetate (TAC).

In addition, when Y>0, the cellulose ester is preferably cellulose acetate propionate (CAP). In this case, it is preferable that X and Y satisfy any of the following: 0.95≦X≦2.25, 0.1≦Y≦1.2, 2.15≦X+Y≦2.45.

By using cellulose acetate or cellulose acetate propionate that meets these conditions, a resin layer with excellent retardation, mechanical strength, and resistance to environmental changes can be obtained.

Also, to obtain the desired optical properties, cellulose acetates with different degrees of substitution may be mixed. There are no particular limitations on the mixing ratio of the different cellulose acetates.

From the viewpoint of mechanical strength, the number average molecular weight (Mn) of the cellulose ester is preferably within the range of 2×10 ⁴ to 3×10 ⁵ , more preferably within the range of 2×10 ⁴ to 1.2×10 ⁵ , and even more preferably within the range of 4×10 ⁴ to 8×10 ⁴ .

The number average molecular weight (Mn) of cellulose ester can be measured in the same manner as for (meth)acrylic resins described below.

From the viewpoint of mechanical strength, the weight average molecular weight (Mw) of the cellulose ester is preferably within the range of 2×10 ⁴ to 1×10 ⁶ , more preferably within the range of 2×10 ⁴ to 1.2×10 ⁵ , and even more preferably within the range of 4×10 ⁴ to 8×10 ⁴ .

The raw cellulose for cellulose ester is not particularly limited, but examples include cotton linters, wood pulp, kenaf, etc. Furthermore, the cellulose esters obtained from these may be mixed in any desired ratio.

Cellulose esters such as cellulose acetate and cellulose acetate propionate can be synthesized by known methods.

Generally, the raw material cellulose, organic acid (acetic acid, propionic acid, etc.), acid anhydride (acetic anhydride, propionic anhydride, etc.) and catalyst (sulfuric acid, etc.) are mixed together. The cellulose is then esterified and the reaction is allowed to proceed until a cellulose triester is produced.

In triesters, the three hydroxy groups in one glucose unit are replaced with an organic acyl acid.

By using two types of organic acids at the same time, it is possible to synthesize mixed ester type cellulose esters, such as cellulose acetate propionate and cellulose acetate butyrate.

The cellulose triester is then hydrolyzed to give a cellulose ester having the desired degree of acyl substitution.
Thereafter, the cellulose ester is finally obtained through steps such as filtration, precipitation, washing, dehydration, drying, etc. Specifically, the cellulose ester can be synthesized by referring to the method described in JP-A-10-45804.

(2.1.1.2) Cycloolefin Resin The cycloolefin resin is preferably a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and another monomer copolymerizable with the cycloolefin monomer.

The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton. Among them, a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferable.

In the above general formula (A-1), R ¹ to R ⁴ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. p represents an integer of 0 to 2. However, R ¹ to R ⁴ do not all represent hydrogen atoms at the same time, R ¹ and R ² do not both represent hydrogen atoms, and R ³ and R ⁴ do not both represent hydrogen atoms.

In the above general formula (A-1), the hydrocarbon group having 1 to 30 carbon atoms represented by R ¹ to R ⁴ is, for example, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Examples of such linking groups include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

In the above general formula (A-1), examples of the polar group represented by R ¹ to R ⁴ include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, and a cyano group. Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group is preferable. In particular, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable from the viewpoint of solubility during solution casting.

In the above general formula (A-1), p is preferably 1 or 2 from the viewpoint of increasing heat resistance. When p is 1 or 2, the resulting polymer is bulky and the glass transition temperature is easily improved. In addition, it becomes somewhat responsive to humidity, making it easier to control the curl balance of the laminate having a resin layer.

In the above general formula (A-2), ^R5 represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. ^R6 represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). p represents an integer of 0 to 2.

R ⁵ in the above general formula (A-2) is preferably a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.

In the above general formula (A-2), ^R6 is preferably a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group or an aryloxycarbonyl group from the viewpoint of solubility during solution casting.

In the above general formula (A-2), p is preferably 1 or 2 from the viewpoint of improving heat resistance. When p is 1 or 2, the resulting polymer is bulky and the glass transition temperature is easily improved.

From the viewpoint of improving the solubility in an organic solvent, the cycloolefin monomer is preferably a cycloolefin monomer having the structure represented by the above general formula (A-2). In general, by breaking the symmetry of an organic compound, the crystallinity is reduced and the solubility in an organic solvent is improved. R ⁵ and R ⁶ in the general formula (A-2) are substituted on only one side of the carbon atoms constituting the ring with respect to the symmetric axis of the molecule, so that the symmetry of the molecule is low. That is, the cycloolefin monomer having the structure represented by the general formula (A-2) is suitable for producing a resin layer by a solution casting method because of its high solubility.

The content of the cycloolefin monomer having the structure represented by general formula (A-2) in the cycloolefin resin is preferably 70 mol% or more relative to the total number of moles of all cycloolefin monomers constituting the cycloolefin resin. Also, it is more preferable that it is 80 mol% or more, and even more preferable that it is 100 mol%. When the content of the cycloolefin monomer having the structure represented by general formula (A-2) is 70 mol% or more, the orientation of the cycloolefin resin is increased, and the phase difference (retardation) value is likely to increase.

Specific examples of cycloolefin monomers having a structure represented by general formula (A-1) are shown below as exemplary compounds 1 to 14. Specific examples of cycloolefin monomers having a structure represented by general formula (A-2) are shown below as exemplary compounds 15 to 34.

Examples of copolymerizable monomers that can be copolymerized with cycloolefin monomers include copolymerizable monomers that can be ring-opening copolymerized with cycloolefin monomers, and copolymerizable monomers that can be addition copolymerized with cycloolefin monomers.

Examples of copolymerizable monomers capable of ring-opening copolymerization include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, (meth)acrylates, etc. Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 carbon atoms (preferably 2 to 8), such as ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

The content of the cycloolefin monomer in a copolymer of a cycloolefin monomer and a copolymerizable monomer is preferably within the range of 20 to 80 mol %, and more preferably within the range of 30 to 70 mol %, based on the total of all monomers constituting the copolymer.

As described above, the cycloolefin resin is a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the above general formula (A-1) or (A-2). Examples of such polymers include the following.
1) Ring-opening polymer of cycloolefin monomer; 2) Ring-opening copolymer of cycloolefin monomer and a copolymerizable monomer capable of ring-opening copolymerization therewith; 3) Hydrogenated product of ring-opening (co)polymer of 1) or 2) above; 4) (co)polymer obtained by cyclizing ring-opening (co)polymer of 1) or 2) above by Friedel-Crafts reaction and then hydrogenating it; 5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound; 6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof; 7) Alternating copolymer of cycloolefin monomer and (meth)acrylate.

The polymers 1) to 7) above can all be obtained by known methods, for example, the methods described in JP-A-2008-107534 and JP-A-2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization 2) above can be, for example, those described in paragraphs 0019 to 0024 of JP-A-2008-107534. The catalyst used in the hydrogenation 3) and 6) above can be, for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534. The acidic compound used in the Friedel-Crafts reaction 4) above can be, for example, those described in paragraph 0029 of JP-A-2008-107534. The catalyst used in the addition polymerization 5) to 7) above can be, for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606. The alternating copolymerization reaction of 7) above can be carried out, for example, by the method described in paragraphs 0071 to 0072 of JP 2005-227606 A.

Among them, the polymers of 1) to 3) or 5) above are preferred, and the polymers of 3) or 5) above are more preferred. That is, from the viewpoint of increasing the glass transition temperature and light transmittance of the resulting resin, the cycloolefin resin preferably contains at least one of a structural unit represented by the following general formula (B-1) and a structural unit represented by the following general formula (B-2). It is more preferred that the cycloolefin resin contains only a structural unit represented by general formula (B-2), or contains both a structural unit represented by general formula (B-1) and a structural unit represented by general formula (B-2). The structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).

In the above general formula (B-1), X represents -CH=CH- or -CH ₂ CH ₂ -, and R ¹ to R ⁴ and p have the same meanings as R ¹ to R ⁴ and p in the above general formula (A-1), respectively.

In the above general formula (B-2), X represents -CH=CH- or -CH ₂ CH ₂ -, and R ⁵ to R ⁶ and p have the same meanings as R ⁵ to R ⁶ and p in general formula (A-2), respectively.

The cycloolefin resin used in the present invention may be a commercially available product. Examples of commercially available cycloolefin resins include "ARTON (registered trademark) G780", "ARTON (registered trademark) F", "ARTON (registered trademark) R4500, R4900, R5000", and "ARTON (registered trademark) RX4500" (all manufactured by JSR Corporation).

The intrinsic viscosity [η]inh of the cycloolefin resin at 30° C. is preferably within the range of 0.2 to 5 cm ³ /g, more preferably within the range of 0.3 to 3 cm ³ /g, and even more preferably within the range of 0.4 to 1.5 cm ³ /g.

The number average molecular weight (Mn) of the cycloolefin resin is preferably within the range of 8,000 to 100,000, more preferably within the range of 10,000 to 80,000, and even more preferably within the range of 12,000 to 50,000.
The weight average molecular weight (Mw) of the cycloolefin resin is preferably within a range of 20,000 to 300,000, more preferably within a range of 30,000 to 250,000, and further preferably within a range of 40,000 to 200,000. The weight average molecular weight (Mw) can be measured by the same method as that for the (meth)acrylic resin described above.

By having the intrinsic viscosity [η]inh, number average molecular weight, and weight average molecular weight (Mw) within the above ranges, the cycloolefin resin has good heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as a resin layer.

The glass transition temperature (Tg) of cycloolefin resins is usually 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C. Having a Tg of 110°C or higher makes it possible to suppress deformation under high temperature conditions. On the other hand, having a Tg of 350°C or lower makes molding easier and suppresses deterioration of the resin due to heat during molding processing.

The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total mass of the resin layer.

(2.1.1.3) Polyimide Polyimide is synthesized by a polymerization reaction between a tetracarboxylic dianhydride and a diamine.

Examples of the tetracarboxylic dianhydride include aromatic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and alicyclic tetracarboxylic dianhydrides. Among these, aromatic tetracarboxylic dianhydrides are preferred.
The diamine may be an aromatic diamine, an aliphatic diamine, or an alicyclic diamine, and among these, an aromatic diamine is preferred.

The weight average molecular weight (Mw) of the polyimide is preferably within the range of 100,000 to 300,000, and more preferably within the range of 130,000 to 250,000. By being within the above range, it is possible to prevent the resin layer from breaking due to the transport tension during transport. The weight average molecular weight (Mw) can be measured in the same manner as for the (meth)acrylic resin described above.

The polyimide content is preferably 60% by mass or more, and more preferably 70% by mass or more, relative to the total mass of the resin layer.

(2.1.2) Dye Compound The first resin layer contains a dye compound. The dye compound has a maximum absorption wavelength in the range of 360 to 379 nm in an ultraviolet-visible light absorption spectrum in a wavelength range of 300 to 460 nm. By containing the dye compound, the light transmittance in a certain wavelength range can be adjusted to within a specific range. Hereinafter, unless otherwise specified, the maximum absorption wavelength of each dye compound refers to the maximum absorption wavelength in the absorption spectrum in the wavelength range of 300 to 460 nm.

The dye compound has the above-mentioned light absorption properties, and thus can protect the light emitting element (particularly the organic EL element) or the light emitting device from external light and suppress deterioration. There are no particular limitations on the dye compound, so long as it has the above-mentioned light absorption properties. However, it is preferable that the dye compound does not have fluorescence or phosphorescence properties (photoluminescence), which would impair the display properties of the organic EL element.

The dye compound is not particularly limited in structure, etc., as long as it has the above-mentioned light absorption characteristics. Examples of the dye compound include organic compounds and inorganic compounds. From the viewpoint of dispersibility in the resin component and transparency of the first resin layer, it is preferable that the dye compound is an organic compound.

Examples of the organic compounds include azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, methine compounds, porphyrin compounds, dicyanomethine compounds, and benzotriazole compounds. Among these, benzotriazole compounds are preferred.

The benzotriazole-based compound preferably has a structure represented by the following general formula (1) or (2). Dye compounds having these structures have extremely high ultraviolet absorption ability and low light absorptance in the wavelength range of 450 to 800 nm. Therefore, the average light transmittance of the first resin layer in the ultraviolet range can be made extremely low, and the average light transmittance in the wavelength range of 450 to 800 nm can be adjusted to 87% or more.

From the viewpoints of dispersibility in the resin, which is a film-forming component of the first resin layer, and transparency of the first resin layer, it is preferable that the dye compound is a compound having a structure represented by the following general formula (1) or (2). The compound has a substituent of a specific structure on the benzotriazole skeleton, and is therefore highly hydrophobic. This strengthens the interaction between the compound, the resin, and other additives, suppresses decomposition of the compound by light, and is thought to improve the light resistance of the compound. In addition, due to the relationship between the sp values of the resin and the compound, the resin and the compound are highly compatible. Therefore, even if the compound is contained in the resin in an amount necessary to form a desired absorption spectrum, it is thought that bleeding out or whitening is unlikely to occur.

(In the formula, R ₁₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an amino group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group. R ₁₂ represents a hydrogen atom or a hydroxy group.)

(In the formula, R ₂₁ represents a hydrogen atom or a hydroxy group. R ₂₂ , R ₂₃ , and R ₂₄ represent an alkyl group, an alkoxy group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group.)

The number of carbon atoms in the alkyl group portion of the substituents represented by R ₁₁ , R ₂₂ , R ₂₃ and R ₂₄ is preferably within the range of 1 to 20, more preferably within the range of 1 to 10. The alkyl group portion may be linear, branched, cyclic or a combination thereof. The number of carbon atoms in the aryl group is preferably within the range of 5 to 30. The aryl group may have a heteroatom. The aromatic ring in the aryl group may be a monocyclic or condensed ring.

Examples of the alkyl group or alkyl group moiety include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, an n-octyl group, and a 2-ethylhexyl group.
Examples of the aryl group include a phenoxy group, a naphthyloxy group, and a 2-methylphenoxy group.
The substituents represented by R ₁₁ , R ₂₂ , R ₂₃ and R ₂₄ may further have a substituent.

Examples of compounds having structures represented by general formula (1) and general formula (2) are given below. However, the dye compounds are not limited to these.

The compounds having the structures represented by the general formulas (1) and (2) according to the present invention can be synthesized by conventionally known methods. An example of the synthesis method is shown below. First, nitroanilines are diazotized. The resulting diazo compound is coupled with sesamol by a conventional method. The resulting nitrophenylazo compound is reduced to synthesize the desired benzotriazole derivative.

　[Synthesis of 6-(5-methoxycarbonyl-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol]

Equip a 300 mL four-neck flask with a ball condenser, thermometer, and stirring device. Add the following ingredients to the four-neck flask and stir for 3 hours at 65-70°C.

6-(5-carboxy-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol 1.10 g (0.0037 mol)
Thionyl chloride 0.90 g (0.0076 mol)
Toluene 173.38g (200.0mL)
N,N-Dimethylformamide 0.18g (0.2mL)

After the solvent is distilled off from the four-neck flask, the following components are added to the four-neck flask and stirred at 70 to 75° C. for 2 hours.
Methanol 0.5g (0.0156 mol)
Pyridine 0.80g (0.0101 mol)
Toluene 130.04g (150.0mL)

The reaction product is washed twice with 100 mL of warm water. 0.1 g of activated carbon is added to the reaction product, and the mixture is stirred under reflux to decolorize. The reaction product is then filtered while hot, and the filtrate is cooled to 5°C. The precipitated crystals are filtered, washed with toluene, and dried at 60°C to obtain 0.5 g of compound (1-8). The yield is 43%.
The resulting compound (1-8) is 6-(5-methoxycarbonyl-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol, and has a maximum absorption wavelength of 377 nm.

(Measurement of maximum absorption wavelength)
The maximum absorption wavelength of a dye compound can be determined by measuring the absorption spectrum of the dye compound in chloroform using, for example, an ultraviolet-visible spectrophotometer "UV-2450" (manufactured by Shimadzu Corporation).

In the present invention, the "maximum absorption wavelength" refers to the wavelength (nm) that shows the maximum and maximal absorbance (absorption intensity) in the ultraviolet-visible light absorption spectrum of the dye compound obtained by measurement.

The dye compounds may be used alone or in combination of two or more. The second resin layer may or may not contain a dye compound.
The content of the dye compound is preferably within a range of 0.01 to 10% by mass, and more preferably within a range of 0.02 to 8% by mass, based on the total mass of the resin as a film-forming component. By being within the above range, the resin layer can sufficiently absorb light in a wavelength range that does not affect the light emission of the light-emitting element or light-emitting device, and deterioration of the light-emitting element or light-emitting device due to external light can be suppressed.

(2.1.3) Plasticizer The resin layer preferably contains a plasticizer. By containing a plasticizer, the flexibility and processability of the resin layer can be improved. Examples of the plasticizer include polyester. The polyester is obtained by polymerizing a dicarboxylic acid and a diol. In addition, it is preferable that 70% or more of the dicarboxylic acid constitutional units (constituent units derived from a dicarboxylic acid) are derived from an aromatic dicarboxylic acid, and 70% or more of the diol constitutional units (constituent units derived from a diol) are derived from an aliphatic diol.

The proportion of structural units derived from aromatic dicarboxylic acids is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The proportion of structural units derived from aliphatic diols is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The polyester may be contained alone or in combination of two or more types.

Examples of aromatic dicarboxylic acids include terephthalic acid; isophthalic acid; naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,4'-biphenyldicarboxylic acid; and ester-forming derivatives thereof.

　Aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid may be used for the polyester, as long as the object of the present invention is not impaired.

Examples of aliphatic diols include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and ester-forming derivatives thereof.

　For the polyester, monoalcohols such as butyl alcohol, hexyl alcohol, octyl alcohol, etc., and polyhydric alcohols such as trimethylolpropane, glycerin, pentaerythritol, etc. may be used as long as the object of the present invention is not impaired.

　Polyesters can be synthesized by known methods such as direct esterification and transesterification. Polycondensation catalysts used in polyester synthesis include known antimony compounds such as antimony trioxide and antimony pentoxide; germanium compounds such as germanium oxide; titanium compounds such as titanium acetate; and aluminum compounds such as aluminum chloride. However, polycondensation catalysts are not limited to these.

Preferred polyesters include polyethylene terephthalate, polyethylene terephthalate-isophthalate copolymer, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer, polyethylene-2,6-naphthalene dicarboxylate, polyethylene-2,6-naphthalene dicarboxylate-terephthalate copolymer, polyethylene-terephthalate-4,4'-biphenyl dicarboxylate, poly-1,3-propylene terephthalate, polybutylene terephthalate, polybutylene-2,6-naphthalene dicarboxylate, etc.

More preferred polyesters include polyethylene terephthalate, polyethylene terephthalate-isophthalate copolymer, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer, polybutylene terephthalate, and polyethylene-2,6-naphthalenedicarboxylate.

The plasticizer content is preferably within the range of 0 to 35% by mass, and more preferably within the range of 5 to 30% by mass, relative to the total mass of the resin as a film-forming component.

(2.1.4) Ultraviolet Absorber The resin layer may contain an ultraviolet absorber, if necessary. By containing an ultraviolet absorber, the light absorptance of the resin layer in the ultraviolet region can be further improved.

In the present invention, the term "ultraviolet light absorber" refers to a compound that has the function of absorbing ultraviolet light with a wavelength of at least 400 nm or less. There are no particular limitations on the ultraviolet light absorber as long as it has the above absorption characteristics. In particular, the ultraviolet light absorber used in the present invention is preferably a compound whose maximum absorption wavelength is in the range of 300 to 359 nm in the ultraviolet-visible light absorption spectrum in the wavelength region of 300 to 460 nm.

Examples of ultraviolet absorbents include triazine-based ultraviolet absorbents, benzotriazole-based ultraviolet absorbents, benzophenone-based ultraviolet absorbents, oxybenzophenone-based ultraviolet absorbents, salicylic acid ester-based ultraviolet absorbents, and cyanoacrylate-based ultraviolet absorbents. These may be contained alone or in combination of two or more.

Among them, triazine-based UV absorbers or benzotriazole-based UV absorbers are preferable. Also, triazine-based UV absorbers having two or less hydroxyl groups per molecule or benzotriazole-based UV absorbers having one benzotriazole skeleton per molecule are preferable.

These UV absorbents have good solubility with the above resins. In addition, these UV absorbents have high UV absorption capabilities at wavelengths around 380 nm.

Examples of triazine-based UV absorbers having two or less hydroxy groups in one molecule include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine ("Tinosorb (registered trademark) S" (BASF Corporation)), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine ("TINUVIN (registered trademark) 460" (BASF Corporation)), 2- (4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane reaction products ("TINUVIN (registered trademark) 400" (BASF Corporation)), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyphenyl)-4 Reaction products of 2-(4,6-diphenyl-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester ("TINUVIN (registered trademark) 405" (BASF Corporation)), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol ("TINUVIN (registered trademark) 1577" (BASF Corporation)), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy] Examples include 6,6',6''-(1,3,5-triazine-2,4,6-triyl)tris(3-hexyloxy-2-methylphenol) (LA-F70, manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN (registered trademark) 479, manufactured by BASF Corporation), and 6,6',6''-(1,3,5-triazine-2,4,6-triyl)tris(3-hexyloxy-2-methylphenol) (LA-F70, manufactured by ADEKA Corporation).

Furthermore, examples of benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton per molecule include 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol ("TINUVIN (registered trademark) 928" (BASF Corporation)), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole ("TINUVIN (registered trademark) PS" (BASF Corporation)), and an ester compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) ("TINUVIN (registered trademark) 384-2"). (manufactured by BASF)), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ("TINUVIN (registered trademark) 900" (manufactured by BASF)), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 ("TINUVIN (registered trademark) 1130" (manufactured by BASF)), 2-(2H-benzotriazol-2-yl)-p-cresol ("TINUVIN (registered trademark) P" (manufactured by BASF)), 2(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ("TINUVIN (registered trademark) 34" (manufactured by BASF Corporation), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol ("TINUVIN (registered trademark) 326" (manufactured by BASF Corporation)), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol ("TINUVIN (registered trademark) 328" (manufactured by BASF Corporation)), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol ("TINUVIN (registered trademark) 329" (manufactured by BASF Corporation)), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 and reaction product ("TINUVIN (registered trademark) 213" (manufactured by BASF)), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol ("TINUVIN (registered trademark) 571" (manufactured by BASF)), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole ("Sumisorb (registered trademark) 250" (manufactured by Sumitomo Chemical Co., Ltd.)), 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole ("SeeSorb (registered trademark) 703" (manufactured by Shipro Chemical Co., Ltd.), or "KEMISORB (registered trademark) 73" (manufactured by Shipro Chemical Co., Ltd.)).

Furthermore, examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone-based compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone ("SeeSorb (registered trademark) 106" (manufactured by Shipro Chemical Co., Ltd.)), 2,2'-dihydroxy-4-methoxybenzophenone ("KEMISORB (registered trademark) 111" (manufactured by Chemipro Chemical Co., Ltd.)), and the like.

Furthermore, examples of the salicylic acid ester-based ultraviolet absorbers (salicylic acid ester-based compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate ("TINUVIN (registered trademark) 120" (manufactured by BASF Corporation)), and the like.

Examples of the cyanoacrylate-based ultraviolet absorbers (cyanoacrylate-based compounds) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The ultraviolet absorbing agent may be contained alone or in combination of two or more kinds.
The content of the ultraviolet absorber is preferably within a range of 0.1 to 8 mass %, and more preferably within a range of 0.5 to 5 mass %, based on the total mass of the resin as the film-forming component.

By being within the above range, the light absorptance of the resin layer in the ultraviolet region can be improved. As a result, the laminate protects the light-emitting element or light-emitting device in the display device from external light (ultraviolet rays), and improves the light resistance of the display device when the laminate is attached. In addition, the quality of the display device can be maintained for a long period of time.

(2.1.5) Antioxidant The resin layer preferably contains an antioxidant. By containing an antioxidant, deterioration of the resin layer can be suppressed. Specifically, decomposition of the resin layer due to halogens from residual solvents, phosphoric acid from phosphoric acid-based plasticizers, etc. can be delayed or prevented. In addition, in the present invention, the light absorption waveform in the resin layer can be made sharper by using the above-mentioned dye compound and an antioxidant in combination.

The antioxidant is not particularly limited, but is preferably a hindered phenol compound. Hindered phenol compounds have a high affinity with the dye compound. Their interaction makes the light absorption waveform sharper, suppresses light absorption on the long wavelength side, and reduces the light emission loss of the light emitting element or light emitting device.

Hindered phenol antioxidants include, for example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, etc.

Among these, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], or triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] are preferred. In addition, for example, hydrazine-based metal deactivators such as N,N'-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, or phosphorus-based processing stabilizers such as tris(2,4-di-t-butylphenyl)phosphite may be used in combination.

As the hindered phenol-based antioxidant, commercially available products may be used. Examples of commercially available products include "Irganox (registered trademark) 1076" and "Irganox (registered trademark) 1010" (both manufactured by BASF Japan Ltd.).

The content of the antioxidant is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably within the range of 0.5 to 1% by mass, based on the total mass of the resin as a film-forming component.

(2.1.6) Fine particles The resin layer preferably contains fine particles. By containing fine particles, the light emission loss of the light emitting element or the light emitting device can be reduced. In addition, slipperiness can be imparted to the resin layer.

The fine particles may be of an inorganic compound or an organic compound.
Examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate.

Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, styrene-acrylic resins, silicone resins, polycarbonate, benzoguanamine resins, melamine resins, polyolefins, polyesters, polyamides, polyimides, and polyethylene fluoride. Other examples include crushed fractions of organic polymer compounds such as starch.

Other examples of fine particles include polymer compounds synthesized by suspension polymerization, polymer compounds made spherical by spray drying or dispersion methods, and inorganic compounds.

The average particle size of the primary particles of the microparticles is preferably within the range of 5 to 400 nm, and more preferably within the range of 10 to 300 nm.

The fine particles may be contained in the resin layer mainly as secondary aggregates with a particle size in the range of 0.05 to 0.3 μm. If the average particle size of the primary particles of the fine particles is in the range of 100 to 400 nm, the fine particles may be contained as primary particles without agglomeration.

From the viewpoint of reducing the turbidity of the resin layer, it is preferable that the fine particles contain silicon, and it is particularly preferable that they contain silicon dioxide. Examples of commercially available silicon dioxide fine particles include "Aerosil (registered trademark) R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600" (all manufactured by Nippon Aerosil Co., Ltd.).

Silicon-containing microparticles have a high affinity with the dye compound. By using silicon-containing microparticles in combination with the dye compound, the light absorption waveform in the resin layer can be made sharper. Furthermore, light absorption on the long wavelength side is suppressed, and the luminescence loss of the light-emitting element or light-emitting device can be reduced. As the silicon-containing microparticles, the above-mentioned "Aerosil (registered trademark) R812 or R972" is particularly preferable. These highly hydrophobic microparticles have a high affinity with the dye compound, and the interaction between them can further reduce the luminescence loss of the light-emitting element or light-emitting device.

These fine particles may be contained alone or in combination of two or more kinds.
The content of the fine particles is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably within the range of 0.5 to 2% by mass, based on the total mass of the resin as the film-forming component.

The addition of fine particles is preferably performed by in-line addition and mixing. An example of an in-line mixer is a static mixer. Another example of a static mixer is the static in-pipe mixer "Hi-Mixer SWJ type" (manufactured by Toray Engineering Co., Ltd.).

(2.1.7) Other Additives The resin layer may further contain other additives, such as particles (rubber particles, metal oxide particles, etc.), fibers (acicular particles, cellulose nanofibers, etc.), antistatic agents, release agents, thickeners, etc., as necessary.

(2.2) Method for Producing Resin Layer The method for producing the resin layer is not particularly limited, but is preferably a solution casting method or a melt casting method from the viewpoints of suppressing coloration, foreign matter defects, and optical defects such as die lines, etc. Among these, the solution casting method is preferred from the viewpoints of low temperature in the processing step and the ability to add various additives.

In the solution casting method, a dope containing resin, solvent, and any other ingredients is prepared, and then the dope is cast onto a substrate and then dried to obtain a resin layer.

The method for producing a resin layer using the solution casting method is described below. In particular, when the resin used as the film-forming component is cellulose ester, it is preferable to use the following production method. For other resins, conventionally known methods can be used.

In this specification, when explaining the method for producing the resin layer, the cast membrane is also called a "web." In addition, the web that has been dried and has had some of the solvent removed is also called a "film."

(2.2.1) Dope Preparation Process The dope preparation process will be described. The higher the concentration of the resin in the dope, the lower the drying load after casting on the metal support, which is preferable. However, if the concentration of the cellulose ester is too high, the load during filtration increases, and the filtration accuracy deteriorates. The concentration that satisfies both of these conditions is preferably within the range of 10 to 35% by mass, and more preferably within the range of 15 to 25% by mass.

The solvent contained in the dope may be one type alone or two or more types. It is preferable to use a mixture of a good solvent and a poor solvent for cellulose ester from the viewpoint of production efficiency. Examples of good solvents include methylene chloride and methyl acetate. Examples of poor solvents include methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc.

The dope preferably contains water in the range of 0.01 to 2% by mass. In the film-forming process described below, the solvent removed from the casting film by drying may be recovered and reused to dissolve the cellulose ester.

The cellulose ester can be dissolved in a dope by any of the conventional methods. By combining heating and pressure, the cellulose ester can be heated to a temperature equal to or higher than the boiling point at normal pressure.
In preparing the dope, the dye compound and the like can be dissolved or dispersed by a general method.

Then, the cellulose ester solution is filtered using a suitable filter material such as filter paper. The filter material preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably within the range of 0.001 to 0.008 mm, and even more preferably within the range of 0.003 to 0.006 mm.

There are no particular limitations on the filter material, and any ordinary filter material can be used. Filter materials made of plastics such as polypropylene and Teflon (registered trademark), or metals such as stainless steel, are preferred as they are less susceptible to fiber shedding.

The dope can be filtered by a normal method. For example, the filtration temperature is preferably equal to or higher than the boiling point of the solvent at normal pressure, and is in a range in which the solvent does not boil under pressure. By filtering while heating, the increase in the difference in filtration pressure (differential pressure) before and after filtration can be reduced. The filtration temperature is preferably within the range of 45 to 120°C, more preferably within the range of 45 to 70°C, and even more preferably within the range of 45 to 55°C.

The smaller the filtration pressure, the better. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and even more preferably 1.0 MPa or less.

(2.2.2) Step of casting the dope onto the support to form a casting film Next, the casting of the dope will be described.

The metal support used in the casting process is preferably one with a mirror-finished surface. The metal support is preferably, for example, a stainless steel belt or a cast drum with a plated surface. The casting width is preferably within the range of 1 to 4 m.

The surface temperature of the metal support during the casting process is preferably -50°C or higher and lower than the boiling point of the solvent, more preferably within the range of 0 to 40°C, and even more preferably within the range of 5 to 30°C.

In order for the resin layer to have good planarity, the amount of residual solvent when the casting film (web) is peeled off from the metal support is preferably within the range of 10 to 150% by mass. It is more preferably within the range of 20 to 40% by mass or within the range of 60 to 130% by mass. And it is even more preferably within the range of 20 to 30% by mass or within the range of 70 to 120% by mass.

In the present invention, the amount of residual solvent is defined by the following formula:

Residual Solvent Amount (% by mass)={(M−N)/N}×100
Here, M is the mass of a sample taken at any time during or after the production of the web or film, and N is the mass of M after heating at 115° C. for 1 hour.

(2.2.3) Step of peeling off the cast film from the support The cast film (web) is peeled off from the metal support. As a method for peeling off the web from the metal support, a known method can be used.

(2.2.4) Step of drying the cast film In the step of drying the resin layer, the cast film (web) peeled off from the metal support is further dried. The residual solvent content is preferably 1% by mass or less, more preferably 0.1% by mass or less, and further preferably in the range of 0 to 0.01% by mass.

The web drying process generally involves the roll drying method or the tenter method, which dries the web while transporting it. With the roll drying method, the web is dried by passing it alternately through multiple rolls arranged above and below.

The web is preferably stretched in the longitudinal direction (MD) immediately after peeling from the metal support, where the amount of residual solvent in the web is large. It is also preferable to stretch the web in the transverse direction (TD) using a tenter method in which both ends of the web are held by clips or the like.

There are no particular limitations on the means for drying the web, and typical methods include hot air, infrared rays, heated rolls, microwaves, etc. From the standpoint of simplicity, it is preferable to use hot air.

The drying temperature in the web drying process is preferably in the range of 90 to 200°C, and more preferably in the range of 110 to 190°C. It is preferable to increase the drying temperature in stages.

The preferred drying time depends on the drying temperature, but is preferably within the range of 5 to 60 minutes, and more preferably within the range of 10 to 30 minutes.

The thickness of the film is not particularly limited, but is preferably within the range of 10 to 200 μm, more preferably within the range of 10 to 100 μm, and more preferably within the range of 20 to 60 μm.

The width of the film is preferably within the range of 1 to 4 m. From the viewpoint of productivity, the width is preferably within the range of 1.6 to 4 m, and more preferably within the range of 1.8 to 3.6 m.

(2.2.5) Step of Stretching the Film The stretching operation can be performed sequentially or simultaneously in the longitudinal direction (MD) and transverse direction (TD) of the film. The final stretching ratios in the two mutually perpendicular axial directions are preferably within the ranges of 1.0 to 2.0 times in the MD direction and 1.07 to 2.0 times in the TD direction. Also, it is preferably within the ranges of 1.0 to 1.5 times in the MD direction and 1.07 to 2.0 times in the TD direction.

For example, there is a method in which a difference in peripheral speed is applied to multiple rolls and the difference in roll peripheral speed is used to stretch in the MD direction. There is a method in which both ends of the web are fixed with clips or pins, and the spacing between the clips or pins is widened in the direction of travel to stretch in the MD direction, and a method in which the web is similarly widened in the lateral direction to stretch in the TD direction. Another method is to simultaneously widen the web in both the MD and TD directions to stretch in both the MD and TD directions.

During the film-making process, the width is preferably maintained or the film is stretched in the width direction using a tenter, which may be a pin tenter or a clip tenter.

The film transport tension during the film-forming process, such as in a tenter, depends on the temperature, but is preferably within the range of 120 to 200 N/m, more preferably within the range of 140 to 200 N/m, and even more preferably within the range of 140 to 160 N/m.

If the glass transition temperature of the film is Tg, the temperature of the film during stretching is preferably within the range of (Tg-30) to (Tg+100)°C, more preferably within the range of (Tg-20) to (Tg+80)°C, and even more preferably within the range of (Tg-5) to (Tg+20)°C.

The Tg of the film can be controlled by the type of materials that make up the film and the ratio of those materials. The Tg of the film when dry is preferably 110°C or higher, and more preferably 120°C or higher.

Furthermore, the Tg of the film when dry is preferably 190°C or less, and more preferably 170°C or less. The Tg of the film can be determined by the method described in JIS K7121, etc.

By setting the temperature during stretching to 150°C or higher and the stretch ratio to 1.15 or higher, it is possible to impart an appropriate degree of roughness to the film surface. By imparting an appropriate degree of roughness to the film surface, not only can the slipperiness be improved, but also the surface processability and adhesion to adjacent layers can be improved. The average surface roughness Ra of the film is preferably within the range of 2.0 to 4.0 nm, and more preferably within the range of 2.5 to 3.5 nm.

It is preferable that the average surface roughness Ra (nm) of the film and the polarity of the film itself with respect to the solvent satisfy the following relationship.

(Formula) Ra≧3.5×logP-25.4
After stretching, the film is preferably heat-set. The temperature during heat-setting is preferably higher than the temperature during the final stretching in the TD direction. Heat-setting is preferably performed at a temperature of (Tg-20°C) or lower, usually for 0.5 to 300 seconds. In this case, it is preferable to heat-set the film while sequentially increasing the temperature in two or more divided regions so that the temperature difference is in the range of 1 to 100°C.

The heat-set film is usually cooled to below Tg, and the clipped portions at both ends of the film are cut and wound up. At this time, it is preferable to relax the film by 0.1 to 10% in the TD or MD directions within a temperature range below the final heat-setting temperature and above Tg.

The film is preferably cooled slowly from the final heat setting temperature to Tg at a cooling rate of 100°C per second or less. There are no particular limitations on the method of cooling and relaxation treatment, and any conventionally known method can be used. From the viewpoint of improving the dimensional stability of the film, it is preferable to carry out these treatments while sequentially cooling in multiple temperature ranges.

The cooling rate is calculated by (T1-Tg)/t, where T1 is the final heat setting temperature and t is the time it takes for the film to reach Tg from the final heat setting temperature.

The optimal conditions for these heat fixing conditions and cooling and relaxation treatment conditions vary depending on the types of additives, such as cellulose ester and dye compounds, that make up the film (resin layer). The physical properties of the resulting biaxially stretched film can be measured, and the constituent materials of the optical film can be appropriately selected so that the optical film has the desired characteristics.

(2.3) Physical properties of resin layer (2.3.1) Average light transmittance The first resin layer has an average light transmittance of 87% or more in the wavelength region of 450 to 800 nm. By being within the above range, it is possible to suppress the light emitted from the light emitting element in the display device from being absorbed by the resin layer, and to increase the amount of light emission that is visually recognized. In other words, it is possible to reduce the light emission loss.

The first resin preferably absorbs more ultraviolet light and transmits more visible light. In other words, it is preferable that the average light transmittance in the ultraviolet region is lower, and that the average light transmittance in the wavelength region of 450 to 800 nm is higher.

The light absorption characteristics of the second resin layer are not particularly limited. However, from the viewpoint of further reducing the light emission loss, it is preferable that the visible light transmittance is high.

The light transmittance of the resin layer can be adjusted by including the above-mentioned dye compound.

The average light transmittance in the wavelength region of 450 to 800 nm (visible light region) can be measured by the following method.
The resin layer is conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, the light transmittance is measured using an ultraviolet-visible spectrophotometer (for example, “UV-2450” (manufactured by Shimadzu Corporation)) to determine the arithmetic average value in the wavelength region of 450 to 800 nm.

(2.3.2) Storage Modulus The first resin layer has a storage modulus in the range of 4.0 to 8.0 GPa at 25° C. This makes the first resin layer relatively soft, and can improve the flexibility of the laminate.
In addition, the ratio of the storage modulus of the second resin layer to that of the first resin layer at 25° C. is within the range of 0.7 to 1.5. That is, the storage modulus of the first resin layer and the storage modulus of the second resin layer are approximately the same, so that the flexibility of the laminate can be further improved.

The storage modulus of the resin layer at 25°C can be adjusted by appropriately selecting the type and content of materials (resin, rubber particles, plasticizer, etc.). It can also be adjusted by the manufacturing conditions of the resin layer.

The storage modulus of the resin layer at 25° C. can be measured using a rheometer device “RSA-3” (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
Test conditions (dynamic viscoelasticity test)
Testing machine: Dynamic viscoelasticity measuring device "RSA-3" (manufactured by TA Instruments Japan, Inc.)
Deformation method: tension Preload load: 55g
Temperature range: -70 to 200°C
Frequency: 1.0Hz
Displacement: ±0.1%
Sample: Width 5mm
Chuck distance: 20 mm

(2.3.3) Thickness From the viewpoint of thinning the laminate of the present invention, the thickness of the resin layer is preferably in the range of 10 to 60 μm, more preferably in the range of 15 to 50 μm, and further preferably in the range of 20 to 40 μm. By thinning the laminate, the flexibility can be improved.

From the viewpoint of impact resistance, the glass transition temperature of the resin layer is preferably within the range of -30 to 180°C. If multiple glass transition temperatures are observed when measuring the glass transition temperature of the resin layer, the lowest glass transition temperature observed shall be regarded as the glass transition temperature of the resin layer.

The glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.

(3) Adhesive Layer The laminate of the present invention has an adhesive layer, which allows the layers to be bonded together to form a laminate.

In the present invention, the "adhesive layer" refers to a layer having sufficient adhesiveness to attach the laminate to a display device or to bond the layers in the laminate together. The adhesive layer is preferably made of an adhesive.

The adhesive that is preferably used will be described below.
The first adhesive layer and the second and third adhesive layers that are provided as necessary may be made of the same material and have the same physical properties, or may be made of different materials and have different physical properties.

The adhesive layer may be in the form of a film that can be rolled up, or in the form of a coating layer. A coating layer is formed by applying an adhesive onto an adjacent layer and then curing the applied layer.

The adhesive is not particularly limited, and examples thereof include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these, acrylic-based adhesives are preferred. Acrylic-based adhesives are excellent in transparency and adhesive properties (adhesion, cohesion, and adhesion). They are also excellent in weather resistance, heat resistance, and the like.
Here, the "acrylic adhesive" refers to an adhesive containing an acrylic resin as a main component.

(3.1) Constituent material of adhesive layer (ultraviolet-curable acrylic adhesive) The adhesive layer made of an acrylic adhesive is preferably a layer formed by, for example, ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive. Note that, by ultraviolet curing (ultraviolet polymerization) of an ultraviolet-curable acrylic adhesive, a (meth)acrylic resin is generated.

The "ultraviolet-curable acrylic adhesive" preferably contains a monomer component containing alkyl (meth)acrylate or a partial polymer of the monomer component, a photopolymerization initiator, etc.

(3.1.1) Monomer Component The ultraviolet-curable acrylic pressure-sensitive adhesive contains, as its main component, a (meth)acrylic resin obtained by ultraviolet curing (ultraviolet polymerization) an acrylate-containing monomer component or a partial polymer of the monomer component.
The alkyl (meth)acrylate contained in the monomer component and other monomers that may be contained will be described below. The other monomers that may be contained are preferably monofunctional monomers, but may also be polyfunctional monomers.

(3.1.1.1) Alkyl (meth)acrylate In this specification, "(meth)acrylic" refers to acrylic and methacrylic, and is a general term for both. Furthermore, "alkyl (meth)acrylate" refers to alkyl acrylate and alkyl methacrylate, and is a general term for both.
The alkyl (meth)acrylate in the adhesive layer is preferably an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal.
These may be contained alone or in combination of two or more.

Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having a branched alkyl group having 4 to 9 carbon atoms. Examples of the alkyl (meth)acrylate include n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and isononyl (meth)acrylate.
These may be contained alone or in combination of two or more.

The content of alkyl (meth)acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the monomer component.

(3.1.1.2) Other Monomer Components Examples of monofunctional copolymerization monomers (monofunctional monomers) other than alkyl (meth)acrylates include cyclic nitrogen-containing monomers. The cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure. The cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure.

Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone, and vinyl-based monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. Also included are (meth)acrylic monomers containing a heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.
Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.
Among these, lactam vinyl monomers are preferred.

The content of the cyclic nitrogen-containing monomer is preferably 0.5 to 50 mass%, more preferably 0.5 to 40 mass%, and even more preferably 0.5 to 30 mass%, based on the total mass of the monomer components.

An example of a monofunctional monomer is a hydroxyl group-containing monomer. There are no particular limitations on the hydroxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a hydroxyl group.

Examples of the hydroxy group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Other examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. Among these, hydroxyalkyl (meth)acrylates are preferred.
These may be contained alone or in combination of two or more.

The content of the hydroxyl group-containing monomer is preferably within the range of 1 to 30% by mass, more preferably within the range of 2 to 27% by mass, and even more preferably within the range of 3 to 25% by mass, based on the total mass of the monomer components. By keeping the content within the above range, it is possible to suppress a decrease in the adhesive strength of the adhesive layer. In addition, it is possible to suppress an increase in the viscosity and gelation of the resulting adhesive.

Other examples of monofunctional monomers include carboxyl group-containing monomers and monomers having a cyclic ether group.

There are no particular limitations on the carboxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a carboxyl group.

Examples of the carboxy group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. In addition, itaconic acid or maleic acid may be an anhydride thereof.
Among these, the carboxy group-containing monomer is preferably acrylic acid or methacrylic acid, and more preferably acrylic acid.
These may be contained alone or in combination of two or more.

The monomer having a cyclic ether group is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a cyclic ether group, such as an epoxy group or an oxetane group.

Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. Examples of oxetane group-containing monomers include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc.
These may be contained alone or in combination of two or more.

The content of the carboxyl group-containing monomer or the monomer having a cyclic ether group is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, based on the total mass of the monomer components.

Other monofunctional monomers include, for example, alkyl(meth)acrylates represented by CH ₂ ═C(R ₁ )COOR ₂ , where R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a substituted alkyl group having 1 to 3 carbon atoms, or a cyclic cycloalkyl group.

Examples of the alkyl (meth)acrylate represented by CH ₂ ═C(R ₁ )COOR ₂ include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate.
These may be contained alone or in combination of two or more.

The content of the alkyl (meth)acrylate represented by the above CH ₂ ═C(R ₁ )COOR ₂ is preferably 50 mass% or less, more preferably 45 mass% or less, and even more preferably 40 mass% or less, based on the total mass of the monomer component.

Other monofunctional monomers include, for example, vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol-based acrylic acid ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic acid ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Also included are monomers having a cyclic structure such as terpene (meth)acrylate and dicyclopentanyl (meth)acrylate.

Further, other monofunctional monomers include silane-based monomers containing a silicon atom.
Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

In addition to the monofunctional monomers exemplified above, other monomers may contain polyfunctional monomers as necessary in order to adjust the cohesive strength of the adhesive layer.

The polyfunctional monomer is not particularly limited as long as it is a monomer having at least two polymerizable functional groups having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group.

Examples of polyfunctional monomers include ester compounds of polyhydric alcohols and (meth)acrylic acid such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate.

Of these, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate is preferred.
These may be contained alone or in combination of two or more.

The content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, etc., but is preferably 3 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less, relative to the total mass of the monofunctional monomer. In addition, the content of the polyfunctional monomer is preferably 0.001 mass% or more. By being within the above range, the adhesive strength of the adhesive layer can be improved.

The monomer component may contain a partial polymer of the above monomer component.

(3.1.2) Photopolymerization initiator The ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention preferably contains a photopolymerization initiator.
By including a photopolymerization initiator, the monomer components can be polymerized sufficiently.

The photopolymerization initiator is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization, and any commonly used photopolymerization initiator can be suitably used. Examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

Further examples thereof include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) 819" (manufactured by IGM Resins B.V.)), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) TPO H" (manufactured by IGM Resins B.V.)), and the like.
These may be contained alone or in combination of two or more.

The content of the photopolymerization initiator is preferably within the range of 0.005 to 0.5% by mass, and more preferably within the range of 0.02 to 0.1% by mass, based on the total mass of the monomer components. By being within the above range, ultraviolet curing (ultraviolet polymerization) can proceed sufficiently.

(3.1.3) Others The ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention may further contain a silane coupling agent, a crosslinking agent, and the like.

Silane coupling agents include, for example, epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

The content of the silane coupling agent is preferably 1% by mass or less, more preferably in the range of 0.01 to 1% by mass, and even more preferably in the range of 0.02 to 0.6% by mass, based on the total mass of the monomer components.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxides, etc. Among these, isocyanate-based crosslinking agents are preferred.
These may be contained alone or in combination of two or more.

An isocyanate-based crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or by polymerization, etc.) in one molecule. Examples of isocyanate-based crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.

The content of the crosslinking agent is preferably 5% by mass or less, more preferably in the range of 0.01 to 5% by mass, even more preferably in the range of 0.01 to 4% by mass, and particularly preferably in the range of 0.02 to 3% by mass, based on the total mass of the monomer components.

In addition to the above components, the UV-curable acrylic adhesive may contain other additives as appropriate depending on the application. Examples of such additives include tackifiers; fillers such as hollow glass balloons; plasticizers; anti-aging agents; and antioxidants. Note that tackifiers refer to substances that are solid, semi-solid, or liquid at room temperature, such as rosin derivative resins, terpene resins, petroleum resins, and oil-soluble phenolic resins.

It is preferable to adjust the viscosity of the UV-curable acrylic adhesive to a level suitable for application. The viscosity can be adjusted, for example, by adding various resins such as thickening additives, polyfunctional monomers, etc., or by partially polymerizing the monomer components in the UV-curable acrylic adhesive. The partial polymerization may be carried out before or after adding various polymers such as thickening additives, polyfunctional monomers, etc.

The viscosity of the ultraviolet-curable acrylic adhesive varies depending on the content of additives, etc. Therefore, the polymerization rate when the monomer components in the ultraviolet-curable acrylic adhesive are partially polymerized cannot be uniquely determined. However, as a guideline, the polymerization rate is preferably 20% or less, more preferably within the range of 3 to 20%, and even more preferably within the range of 5 to 15%.
In addition, by controlling the polymerization rate to 20% or less, the viscosity can be adjusted to a level suitable for application work.

(3.2) Method for Producing Adhesive Layer The adhesive layer can be produced by applying an ultraviolet-curable acrylic adhesive onto an adjacent layer, irradiating it with ultraviolet light, and ultraviolet curing (ultraviolet polymerization).
Alternatively, an ultraviolet-curable acrylic adhesive may be applied onto a substrate, and then irradiated with ultraviolet light to effect ultraviolet curing (ultraviolet polymerization), thereby producing a film-like adhesive layer.

The substrate is not particularly limited, and examples include release films, transparent resin films, etc.

Examples of release films include release resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; and thin materials such as nets, foam sheets, metal foils, and laminates of these. Among these, resin films are preferred from the viewpoint of excellent surface smoothness.

Examples of release resin films include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the release film is preferably within the range of 5 to 200 μm, and more preferably within the range of 5 to 100 μm.

If necessary, the release film is preferably subjected to a release treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent. It is also preferable to perform an anti-soiling treatment using silica powder or the like. In addition, anti-static treatments such as coating, kneading or deposition may be performed. In particular, release treatment using a silicone-based, fluorine-based or long-chain alkyl-based release agent makes it easier to peel off the film-like adhesive layer.

The transparent resin film is not particularly limited, but is preferably transparent and composed of a single layer film.
Examples of transparent resin films include polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide.
Among these, polyester, polyimide, or polyethersulfone is preferable.

The thickness of the transparent resin film is preferably within the range of 2 to 200 μm, and more preferably within the range of 20 to 188 μm.

The method for applying the UV-curable acrylic adhesive is not particularly limited, and any conventionally known method can be used. Examples of application methods include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coater methods.

The illuminance of the ultraviolet light irradiated to the ultraviolet-curable acrylic adhesive is preferably within the range of 5 to 200 mW/ ^cm2 . By setting the illuminance of the ultraviolet light to 5 mW/ ^cm2 or more, the polymerization reaction time can be shortened, resulting in excellent productivity. Furthermore, by setting the illuminance of the ultraviolet light to 200 mW/cm2 or ^less , the photopolymerization initiator can be prevented from being rapidly consumed. As a result, the polymerization proceeds sufficiently, and a high molecular weight polymer ((meth)acrylic resin) can be obtained. This allows the adhesive layer to have excellent holding power, especially at high temperatures.
The integrated amount of ultraviolet light is preferably within the range of 100 to 5000 mJ/ ^cm2 .

The ultraviolet lamp used in the present invention is not particularly limited, but is preferably an LED lamp. The LED lamp emits less heat than other ultraviolet lamps, so that the temperature rise during the ultraviolet curing of the ultraviolet curing acrylic adhesive can be suppressed. This allows a polymer with a high molecular weight to be obtained, and an adhesive layer with sufficient cohesive strength can be obtained, thereby increasing the holding power at high temperatures when the adhesive sheet is made.
The ultraviolet lamp may be a combination of a plurality of ultraviolet lamps. As for the irradiation method, ultraviolet light may be intermittently irradiated, and a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated may be provided.

The final polymerization rate of the monomer components in the UV-curable acrylic adhesive is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

The peak wavelength of the ultraviolet light irradiated onto the ultraviolet-curing acrylic adhesive is preferably within the range of 200 to 500 nm, and more preferably within the range of 300 to 450 nm. When the peak wavelength of the ultraviolet light is 500 nm or less, the photopolymerization initiator decomposes and the polymerization reaction begins. Furthermore, when the peak wavelength of the ultraviolet light is 200 nm or more, the scission of the polymer chain can be suppressed, and sufficient adhesion can be obtained.

Since the polymerization reaction is easily inhibited by oxygen in the air, it is preferable to block oxygen. Methods for blocking oxygen include creating a release film on the coating layer of the UV-curable acrylic adhesive, and carrying out the polymerization reaction in a nitrogen atmosphere. Examples of release films include the release films mentioned above.

(3.3) Physical Properties of Adhesive Layer From the viewpoint of making the final laminate thinner, the thickness of the adhesive layer is preferably within the range of 2 to 60 μm, more preferably within the range of 2 to 20 μm, and even more preferably within the range of 5 to 15 μm.

The weight average molecular weight (Mw) of the resin material (e.g., (meth)acrylic resin) used in the adhesive layer is preferably within the range of 100,000 to 5,000,000, and more preferably within the range of 200,000 to 1,000,000, from the viewpoint of controlling the storage modulus.

The weight average molecular weight (Mw) of the resin material used in the adhesive layer is preferably smaller than the weight average molecular weight (Mw) of the resin material used in the optical film. This allows the effects of the present invention to be obtained more efficiently.

The weight average molecular weight (Mw) of the resin material can be measured using a gel permeation chromatography "HLC8220GPC" (manufactured by Tosoh Corporation) and columns "TSK-GEL G6000", "HXL-G5000", "HXL-G5000", "HXL-G4000", and "HXL-G3000HXL" (all manufactured by Tosoh Corporation, in series).
20 mg±0.5 mg of a sample is dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution is then injected into a column (temperature 40° C.) and measured with an RI detector at a temperature of 40° C., and the value is expressed in terms of styrene.

The glass transition temperature (Tg) of the adhesive layer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower, from the viewpoint of achieving both impact resistance in a low-temperature environment and contrast after bending.

The glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.

(3.4) Bezel in Second Adhesive Layer The second adhesive layer may have a bezel.
In the present invention, the term "bezel" refers to an area that has an extremely low transmittance of visible light and is formed in a frame shape around the periphery of a display device.

By having a bezel, it is possible to house devices for controlling transistors, etc., and ICs for accumulating information. It also protects the display device and improves its strength. On the other hand, by making the bezel thinner, it is possible to make the display device smaller and lighter. It is also possible to make the area in which an image is displayed larger.

The bezel is preferably disposed within the second adhesive layer and in contact with the second resin layer or the glass layer. However, the bezel does not necessarily have to be disposed within the second adhesive layer, and may be disposed within the first adhesive layer or between other layers of the laminate.

The bezel is a colored light-shielding film that contains a dye or pigment. There are no particular limitations on the method of forming the bezel, but it is preferable that it is formed, for example, by a coating method. It is preferable that the bezel is formed in a frame shape on a flat surface.

(4) Glass Layer The laminate of the present invention is attached to a thin glass film, and then attached to a display device.

(4.1) Overview of Glass Layer (Thin Film Glass) The glass layer according to the present invention is preferably a thin film glass from the viewpoint of excellent durability, flatness, etc. Examples of materials for thin film glass include lithium aluminosilicate glass, soda-lime glass, borosilicate glass, silica glass, alkali metal aluminosilicate glass, and aluminosilicate glass with a low alkali content.

The thin film glass is preferably an alkali-free glass that contains substantially no alkali components. Specifically, the content of alkali components is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less, relative to the total mass of the thin film glass.

By reducing the alkaline content, it is possible to suppress the replacement of cations on the surface of the thin glass film, and to prevent a phenomenon known as soda blowing. This prevents the density of the thin glass surface from decreasing, making it less susceptible to breakage.

The thickness of the thin film glass is preferably within a range of 10 to 50 μm. By making the thickness of the thin film glass 10 μm or more, sufficient impact resistance of the laminate can be obtained. On the other hand, by making the thickness of the thin film glass 50 μm or less, sufficient flexibility of the laminate can be obtained. Furthermore, the thinner the thin film glass is, the thinner the laminate can be, and the thinner the display device can be.
From the viewpoint of achieving both impact resistance and flexibility, the thickness of the thin glass is more preferably within the range of 10 to 40 μm, and further preferably within the range of 10 to 30 μm.

(4.2) Method for Producing Glass Layer (Thin Glass) Thin glass (glass layer) can be produced by commonly known methods, such as the float method, down-draw method, overflow down-draw method, etc. Among these, the overflow down-draw method or float method is preferred because the surface of the thin glass does not come into contact with the forming member during production, and the surface of the obtained thin glass is less likely to be scratched. Among these, the float method is preferred from the viewpoint of obtaining a thin glass having a thickness in the range of 10 to 50 μm.

Normally, the thinner the glass, the weaker it is and the more susceptible it is to breakage, making it difficult to handle and process thin-film glass on its own. However, by processing the thin-film glass while temporarily adhering it to a thicker support substrate (carrier substrate), and then peeling off the support substrate as a post-processing step, it is possible to make the thin-film glass easier to handle and process.

For example, in the technology described in International Publication No. 2017/066924, soda-lime glass having a thickness of less than 100 μm can be produced by the following process. Note that FIG. 4 is a schematic diagram showing an example of a method for producing thin-film glass.

(Step 1)
4, in step 1, a thin film glass 22 is prepared so that a first surface of the thin film glass is in contact with a carrier substrate 21 having a bonding surface. Then, a contact film 23 having adhesive force is pressure-bonded to a second surface opposite to the first surface.

That is, the thin-film glass material is poured to the desired thickness onto a carrier substrate 21 that has sufficient strength and a thickness that is easy to process. This creates a first surface of the thin-film glass 22 that is in contact with the carrier substrate 21. Then, a contact film 23 is pressed onto a second surface on the opposite side to the first surface.

(Step 2)
As shown in FIG. 4, in step 2, the thin glass 22 is peeled off from the carrier substrate 21 by the contact film 23 having high adhesive strength.

(Step 3)
4, in step 3, a weakening treatment (electromagnetic radiation irradiation 24) is performed to weaken the adhesive strength of the contact film, thereby removing the contact film 23 from the second surface of the thin glass 22.

In this way, the contact film 23 is used to safely hold the thin-film glass 22, thereby protecting the thin-film glass 22. The exposed surface of the thin-film glass 22 can be protected from, for example, mechanical damage, and can be handled safely and easily.

Examples of materials for the contact film include polyolefins (PO) such as polyethylene terephthalate (PET) and polyethylene (PE).

The contact film is typically adhered to the thin glass by an adhesive layer made of an adhesive provided on one side of the substrate. The contact film may also be adhered directly to the thin glass by the adhesive properties of the contact film itself.

The adhesion strength between the contact film and the second surface of the thin film glass is appropriately selected so that the peeling device transmits sufficient force to peel the thin film glass from the carrier substrate.

The contact film is preferably in the form of a foil or tape. By forming it into a foil or tape, it can be wound into a roll. The thickness of the contact film is preferably 50 μm or more, more preferably 80 μm or more, more preferably 125 μm or more, and particularly preferably 150 μm or more.

The thin glass is preferably fabricated on a carrier substrate by the aforementioned downdraw method, overflow downdraw method, or float method.

The thickness of the carrier substrate is preferably 100 μm or more, more preferably 300 μm or more, and even more preferably 500 μm or more.
Furthermore, the width of the carrier substrate is preferably 3 inches or more (1 inch is 2.54 cm), more preferably 6 inches or more, even more preferably 8 inches or more, and particularly preferably 12 inches or more.

In particular, the carrier substrate is preferably equal to or larger than the first generation glass substrate size, for example, second to eighth generation sizes. Alternatively, it may be even larger, for example, 1x1m to 3x3m. The carrier substrate may be of various shapes, such as rectangular, elliptical, circular, etc.

The thin glass film, together with the contact film, is peeled off from the carrier substrate by the adhesive force of the contact film. The contact film is then peeled off, leaving a single thin glass film.

Before peeling the contact film from the thin glass, it is preferable to weaken the adhesive strength of the contact film by subjecting it to a treatment to weaken its adhesive strength. Specifically, it is preferable to reduce the adhesive strength to 0.5 N/25 mm or less.

In the weakening process, it is preferable to use electromagnetic radiation, such as infrared, ultraviolet, or visible light, as appropriate. The electromagnetic radiation may be narrowband or may cover a wider band depending on the adhesive material used. It may also be laser radiation.

It is preferable to select electromagnetic radiation having a wavelength outside the visible spectrum so that the adhesive strength does not deteriorate under exposure to visible light. Some commercially available adhesive materials can be at least partially deactivated by exposure to electromagnetic radiation and can be used as contact films.

If increasing or decreasing the temperature reduces the adhesion of the contact film, heat treatment may be used as a weakening treatment.

The electromagnetic radiation is preferably applied from the outer surface of the contact film, i.e., the side to which the thin glass is not adhered.

An example of a contact film is "NDS4150-20" (manufactured by Dao Ming Optical Co., Ltd.). A corresponding weakening treatment is exposure to ultraviolet light with a wavelength of 365 nm.

Specific methods and conditions for producing the thin-film glass will be explained in the Examples section. In addition, commercially available products manufactured by, for example, SCHOTT and Nippon Electric Glass Co., Ltd., can be used as the thin-film glass.

3. Method for Producing the Laminate The method for producing the laminate of the present invention is not particularly limited, and examples thereof include a method in which a cured layer, a resin layer, and an adhesive layer are disposed in this order.

4. Physical Properties of the Laminate The thickness of the laminate of the present invention is preferably within a range of 100 to 300 μm, and more preferably within a range of 100 to 200 μm, from the viewpoint of achieving both impact resistance and flexibility.

5. Display Device The display device of the present invention is characterized by comprising the laminate described above. The laminate preferably has a glass layer.
In addition, it is preferable that the first resin layer is disposed closer to the viewing side of the display device than the second resin layer. By disposing a layer having ultraviolet ray absorbing properties closer to the viewing side of the laminate, not only the display device but also other layers of the laminate can be protected from ultraviolet ray.

The display device of the present invention can be obtained by attaching the laminate to the surface of the display device described below. The laminate preferably has a glass layer. There are no particular limitations on the attachment method. From the viewpoint of achieving both impact resistance and flexibility, it is preferable to use the adhesive described above for bonding.

The display device of the present invention may also have a polarizing plate between the laminate and the display device described below. However, since the laminate can suppress external light reflection, that is, since the laminate has some of the function of a polarizing plate, it does not necessarily have to have a polarizing plate.

In the present invention, a "display device" refers to a device having a display mechanism, and has a light-emitting element or a light-emitting device as a light source. In addition, in the present invention, a device having a display mechanism is also called a "display member."

Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (such as a field emission display device (FED) and a surface field emission display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection type display device (such as a grating light valve (GLV) display device and a display device having a digital micromirror device (DMD)), a piezoelectric ceramic display, and the like.
Examples of the liquid crystal display device include a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device.

These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images.
Among these, an organic EL display device or a touch panel display device is preferable, and an organic EL display device is more preferable.

The display device of the present invention is equipped with the above-mentioned laminate (cover member), thereby achieving both light resistance and impact resistance.

FIG. 5 shows an example of application to an organic EL display, which is an example of a display device.
5, the display device 100 has an organic EL layer 9 on the surface of the glass layer 6 opposite to the second adhesive layer 7. In addition, a third adhesive layer 8 may be provided between the glass layer 6 and the organic EL layer 9. The third adhesive layer may be made of the same material and have the same physical properties as the first adhesive layer and the second adhesive layer, or may be made of a different material and have different physical properties.

Normally, an organic EL display is composed of an organic EL layer consisting of an electrode/electron transport layer/light-emitting layer/hole transport layer/transparent electrode, and a polarizing plate equipped with a retardation plate (lambda/4 plate) to improve image quality. However, since the laminate of the present invention has some of the functions of a polarizing plate, it does not necessarily have to have a polarizing plate.

The display device of the present invention may also be a foldable display. A foldable display is preferably a single continuous display that can be folded in half when carried, reducing its size by half and improving portability. It is also preferable that the foldable display is thin and lightweight.

The laminate of the present invention has good impact resistance and is unlikely to leave creases even when folded repeatedly. In addition, the contrast can be maintained even after repeated folding. Therefore, in a foldable display, the visibility after repeated folding is excellent, specifically, the suppression of image distortion at the folded portion. In addition, since the laminate of the present invention has good light resistance, the quality can be maintained for a long period of time even when applied to a mobile device used outdoors.

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the examples, the terms "parts" and "%" are used, but they represent "parts by mass" or "% by mass" unless otherwise specified.
In the following examples, operations were carried out at room temperature (25° C.) unless otherwise specified.

1. Preparation of Laminate In this embodiment, after preparing a resin layer, a cured layer was prepared on the resin layer to prepare a two-layer film. In detail, a two-layer film in which a first cured layer was prepared on a first resin layer and a two-layer film in which a second cured layer was prepared on a second resin layer were prepared, respectively. Then, the two two-layer films were laminated together via an adhesive layer to prepare a laminate. The layers were laminated together so that they were arranged in the order of the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, and the second resin layer.

(1) Preparation of resin layer (1.1) Preparation of resin layer 1 (1.1.1) Preparation of dope 1 (silicon dioxide dispersion liquid)
"Aerosil (registered trademark) R812" (manufactured by Nippon Aerosil Co., Ltd., average primary particle diameter 7 nm)
The above components were mixed and stirred for 30 minutes using a dissolver, and then dispersed using a Manton-Gaulin to prepare a silicon dioxide dispersion. The silicon dioxide dispersion was filtered using a fine particle dispersion dilution filter (Advantec Toyo Co., Ltd.: polypropylene wound cartridge filter TCW-PPS-1N).

Dichloromethane 80.960 parts by weight Ethanol 7.040 parts by weight The above silicon dioxide dispersion (10% by weight dispersion) 0.120 parts by weight The above dye compound (2-3) 0.720 parts by weight The above components were stirred at 23° C. for 1 hour, and then 12 parts by weight of acetyl cellulose was added and stirred at 23° C. for 4 hours. Then, the mixture was filtered using Azumi Filter Paper No. 24 manufactured by Azumi Filter Paper Co., Ltd. to prepare Dope 1.

The content of silicon dioxide was 0.1% by mass based on the total mass of the acetyl cellulose. The acetyl cellulose was prepared by a known method using triacetyl cellulose (TAC) with a degree of substitution of 3.0.

(1.1.2) Formation of Resin Layer 1 Next, the above dope 1 was uniformly cast on a stainless steel band support using a belt casting device to form a cast film. The solvent was evaporated on the stainless steel band support until the residual solvent amount in the cast film reached 100%, and the cast film was peeled off from the stainless steel band support. The cast film was heated at 35°C to evaporate the solvent. The cast film from which the solvent had been evaporated was slit into a width of 1.65 m, and the width was held by a tenter and dried at a drying temperature of 160°C. The drying temperature here was also the heat treatment temperature and the stretching temperature.

The residual solvent content was 20% when drying began. The film was then dried for 15 minutes while being transported by multiple rolls through a drying device at 120°C, after which knurling was applied to both ends of the film to a width of 15 mm and a height of 10 μm. The film was wound around a core to obtain resin layer 1. The residual solvent content of resin layer 1 was 0.2%, the thickness was 40 μm, and the number of windings was 6,000 m.

(1.2) Preparation of Resin Layers 2, 4, 6 to 13, and 15 to 18 Resin layers 2, 4, 6 to 13, and 15 to 18 were prepared in the same manner as in the preparation of Resin Layer 1, except that the type of resin, the type and content of the dye compound, and the thickness were changed as shown in Tables I and II.

(1.3) Preparation of Resin Layer 3 Resin layer 3 was prepared in the same manner as in the preparation of resin layer 1 above, except that metal oxide particles were added so that the storage modulus was 6.7 GPa.

(1.4) Preparation of Resin Layer 5 A resin layer 5 was prepared in the same manner as in the preparation of the resin layer 1, except that the amount of ethanol added in the dope 1 was changed from 7.04 parts by mass to 1.65 parts by mass, and the type of resin was changed.

(1.5) Fabrication of Resin Layer 14 (1.5.1) Preparation of Thermoplastic (Meth)acrylic Resin As a thermoplastic (meth)acrylic resin, a MMA (methyl methacrylate)/PMI (phenylmaleimide)/MA (methyl acrylate) copolymer (85/10/5 mass ratio, Mw: 2 million, Tg: 122° C.) was prepared.

(1.5.2) Preparation of Rubber Particles (Graft Copolymer) R1 Rubber particles (graft copolymer) prepared by the following method were used.

The following components were charged into an 8 L polymerization apparatus equipped with a stirrer to prepare solution I.
Deionized water 180.000 parts by weight Polyoxyethylene lauryl ether phosphate 0.002 parts by weight Boric acid 0.473 parts by weight Sodium carbonate 0.047 parts by weight Sodium hydroxide 0.008 parts by weight

After thoroughly replacing the atmosphere inside the polymerization apparatus with nitrogen gas, the internal temperature was adjusted to 80° C., and the following components were added.
Potassium persulfate (added as a 2% by weight aqueous solution) 0.021 parts by weight

Next, a monomer mixture (c') consisting of the following components was prepared.
Methyl methacrylate (methyl methacrylate) 84.6% by mass
n-Butyl acrylate (n-butyl acrylate) 5.9% by mass
Styrene 7.9% by mass
Allyl methacrylate (allyl methacrylate) 0.5% by mass
n-Octyl mercaptan 1.1% by mass

Then, a mixture of the following components was prepared.
Monomer mixture (c') 21.000 parts by mass Polyoxyethylene lauryl ether phosphate 0.070 parts by mass Then, the mixture was continuously added to the above solution I over 63 minutes. The polymerization reaction was further continued for 60 minutes to obtain a hard polymer (crosslinked polymer (c)) contained in the innermost part.

Thereafter, the following components were added to prepare solution II.
Sodium hydroxide (added as a 2% by weight aqueous solution) 0.021 parts by weight Potassium persulfate (added as a 2% by weight aqueous solution) 0.062 parts by weight

Next, a monomer mixture (a') consisting of the following components was prepared.
n-Butyl acrylate (n-butyl acrylate) 80.0% by mass
Styrene 18.5% by mass
Allyl methacrylate (allyl methacrylate) 1.5% by mass

Then, a mixture of the following components was prepared.
Monomer mixture (a') 39.000 parts by mass Polyoxyethylene lauryl ether phosphate 0.250 parts by mass Then, this mixture was continuously added to solution II over a period of 117 minutes.

The following ingredients were then added:
Potassium persulfate (added as a 2% by weight aqueous solution) 0.012 parts by weight The polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer made of acrylic rubber-like polymer (a)). The glass transition temperature (Tg) of the soft layer, calculated by averaging the glass transition temperatures of the homopolymers of the monomers constituting the acrylic rubber-like polymer (a) according to the composition ratio, was -30°C.

Thereafter, the following components were added to prepare solution III.
Potassium persulfate (added as a 2% by weight aqueous solution) 0.040 parts by weight

Then, a monomer mixture (b') consisting of the following components was prepared.
Methyl methacrylate (methyl methacrylate) 97.5% by mass
n-Butyl acrylate (n-butyl acrylate) 2.5% by mass

The following monomer mixture (b') was continuously added to solution III over 78 minutes. The polymerization reaction was continued for an additional 30 minutes to obtain a methacrylic polymer (b).
Monomer mixture (b') 26.100 parts by mass

The obtained methacrylic polymer (b) was poured into a 3% by mass aqueous solution of sodium sulfate to cause salting out and coagulation. Then, after repeated dehydration and washing, the mixture was dried to obtain acrylic graft copolymer particles (rubber particles) R1 having a three-layer structure.
The average particle size of the obtained rubber particles R1 was measured by a zeta potential/particle size measuring system "ELSZ-2000ZS" (manufactured by Otsuka Electronics Co., Ltd.) and found to be 200 nm. The glass transition temperature (Tg) of the rubber particles was -30°C.

(1.5.3) Preparation of Surfactant Solution The following components were mixed and dissolved to prepare a surfactant solution.
Methyl ethyl ketone (MEK) 98.000 parts by mass Phosphanol ML-220 (polyoxyethylene lauryl ether phosphate, manufactured by Toho Chemical Industry Co., Ltd.)
2.000 parts by weight

(1.5.4) Preparation of Dope The following components were charged as a solvent into a dissolution tank in which the nitrogen concentration was controlled to 98.5 vol % and the oxygen concentration was controlled to 1.5 vol %.
Methyl ethyl ketone: 85.300 parts by mass Next, the following components were added to the dissolution tank containing this solvent, and the mixture was stirred for 30 minutes.
Surfactant solution: 15.000 parts by weight Dye compound (2-3): 0.660 parts by weight

Thereafter, the following components were added with stirring, and stirring was continued at 23° C. for 1 hour to disperse the rubber particles (graft copolymer).
Rubber particles (graft copolymer particles) 2.200 parts by mass The following components were then charged into a dissolution tank with stirring, and the mixture was stirred at 23° C. for 4 hours to completely dissolve the solids, thereby completing the dope.
Thermoplastic (meth)acrylic resin 8.800 parts by mass

(1.5.5) Formation of resin layer 14 As a substrate, a PET film "TN100" (manufactured by Toyobo Co., Ltd., thickness 50 μm, with a release layer containing a non-silicone release agent) was prepared. The above dope was applied onto the release layer of this PET film using a die by a backcoat method, and then dried at 80° C. in an atmosphere with a solvent concentration of 0.18% by volume. Then, the substrate was peeled off to obtain a resin layer 14 with a thickness of 40 μm.

(1.6) Preparation of Resin Layer 19 Resin layer 19 was prepared in the same manner as in the preparation of resin layer 14, except that no dye compound was added and the thickness was changed to 50 μm.

The following resins and dye compounds were used:

(resin)
TAC: triacetyl cellulose DAC: diacetyl cellulose COP: cycloolefin resin "ARTON G7810" (manufactured by JSR Corporation)
CPI: a polymer (polyimide) having a structural unit derived from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and a structural unit derived from 2,2'-bis(trifluoromethyl)benzidine, Mw: 150,000, Tg: 350°C
Acrylic: MMA (methyl methacrylate)/PMI (phenylmaleimide)/MA (methyl acrylate) copolymer (85/10/5 mass ratio, Mw: 2 million, Tg: 122° C.)
PET: Polyethylene terephthalate "E5000" (manufactured by Toyobo Co., Ltd.)

(Pigment Compound)
Compound (1-2): The above-exemplified dye compound (1-2)
Compound (1-13): The above-exemplified dye compound (1-13)
Compound (2-2): The above-exemplified dye compound (2-2)
Compound (2-3): The above-exemplified dye compound (2-3)
Compound (2-8): the above-exemplified dye compound (2-8)
Compound (2-11): The above-exemplified dye compound (2-11)
Compound a: "Kayaset Black A-N" (manufactured by Nippon Kayaku Co., Ltd.)

The chemical structure of the compound is shown below.

(2) Preparation of cured layer (2.1) Preparation of cured layer 1 (2.1.1) Preparation of composition for forming cured layer Resin;
Pentaerythritol tri/tetraacrylate "NK Ester A-TMM-3L" (manufactured by Shin-Nakamura Chemical Co., Ltd.)
100.000 parts by weight of photopolymerization initiator;
"Irgacure 184" (manufactured by BASF Japan Ltd.)
9.000 parts by weight solvent;
Propylene glycol monomethyl ether 20.000 parts by mass Methyl acetate 30.000 parts by mass Methyl ethyl ketone 70.000 parts by mass Additives;
Surfactant: "KF-351A" (polyether modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.)
2.000 parts by mass fine particles;
Polymer silane coupling agent coated silica 100.000 parts by mass

(Preparation of Microparticles)
The above polymer silane coupling agent-coated silica was prepared as follows.
The following components were added to a container, and the atmosphere was replaced with _N2 gas, and then the container was heated at 80°C for 3 hours to prepare a polymer silane coupling agent. The molecular weight of the obtained polymer silane coupling agent was 16000. The molecular weight was measured using a gel permeation chromatography device.

Methyl methacrylate "Light Ester M" (Kyoeisha Chemical Co., Ltd.)
30mL
3-Mercaptopropyltrimethoxysilane "KBM-803" (manufactured by Shin-Etsu Chemical Co., Ltd.)
1 mL
Solvent: tetrahydrofuran 100 mL
Polymerization initiator: azoisobutyronitrile "AIBN" (manufactured by Kanto Chemical Co., Ltd.)
50mg

Next, the following components were ion-exchanged with an ion exchange resin: Then, the water was replaced with ethanol by an ultrafiltration membrane method to prepare 100 g of an ethanol dispersion of silica fine particles ( _SiO2 concentration: 30% by mass).
Silica sol "CATALOID Si-45P" (manufactured by JGC Catalysts and Chemicals Co., Ltd., _SiO2 concentration 30 mass%, average particle size 45 nm, dispersion medium: water)

100 g of this silica fine particle ethanol dispersion and 1.5 g of the above polymer silane coupling agent were dispersed in 20 g (25 mL) of acetone. 20 mg of ammonia water with a concentration of 29.8% by mass was added to this dispersion. The mixture was then stirred at room temperature for 30 hours to allow the polymer silane coupling agent to be adsorbed onto the silica fine particles.

　Then, silica particles with an average particle size of 5 μm were added and stirred for 2 hours to allow the unadsorbed polymer silane coupling agent in the solution to be adsorbed onto the silica particles. Next, the silica particles with an average particle size of 5 μm that had adsorbed the unadsorbed polymer silane coupling agent were removed by centrifugation. 1000 g of ethanol was added to the dispersion of silica particles with the adsorbed polymer silane coupling agent to allow the silica particles to settle. The silica particles were separated, dried under reduced pressure, and dried at 25°C for 8 hours to obtain silica coated with a polymer silane coupling agent. The average particle size of the obtained polymer silane coupling agent-coated silica was 57 nm. The average particle size was measured using a laser particle size measuring device.

(2.1.2) Formation of cured layer 1 On the resin layer prepared above, the composition for forming the cured layer prepared above was applied with a bar coater so that the dry film thickness was 2.5 μm. This coating layer was dried with a dryer in a drying oven at 50° C. for 40 seconds to volatilize the solvent. Then, while purging with nitrogen so that the oxygen concentration is 1.0 volume % or less in this state, the coating layer was cured using an ultraviolet lamp with the illuminance of the irradiation part set to 100 mW/cm ² and the irradiation amount set to 0.2 J/cm ² to prepare cured layer 1.

(3) Preparation of Adhesive Layer (3.1) Preparation of Adhesive Layer 1 (3.1.1) Preparation of UV-Curable Acrylic Adhesive Composition (a-1) A monomer mixture consisting of the following components was prepared.
2-Ethylhexyl acrylate (2EHA) 78.000 parts by weight N-vinyl-2-pyrrolidone (NVP) 18.000 parts by weight 2-hydroxyethyl acrylate (HEA) 4.000 parts by weight

Then, the following components were added as photopolymerization initiators.
1-Hydroxycyclohexyl phenyl ketone 0.035 parts by mass 2,2-Dimethoxy-1,2-diphenylethan-1-one 0.035 parts by mass The following commercially available photopolymerization initiator was used.
1-Hydroxycyclohexyl phenyl ketone: "Omnirad (registered trademark) 184" (having an absorption band in the wavelength range of 200 to 370 nm, manufactured by IGM Resins B.V.)
2,2-Dimethoxy-1,2-diphenylethan-1-one: "Omnirad (registered trademark) 651" (having an absorption band in the wavelength range of 200 to 380 nm, manufactured by IGM Resins B.V.)

Then, ultraviolet light was applied until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s. A prepolymer composition (polymerization rate: 8%) in which some of the monomer components were polymerized was obtained.

Next, the following components were added to the prepolymer composition and mixed to obtain an acrylic pressure-sensitive adhesive composition.
Hexanediol diacrylate (HDDA) 0.150 parts by mass Silane coupling agent "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.)
0.300 parts by weight

The following components were added to the obtained acrylic pressure-sensitive adhesive composition and stirred to obtain an ultraviolet-curable acrylic pressure-sensitive adhesive composition (a-1).
2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (dissolved in n-butyl acrylate to give a solids concentration of 15% by mass and added)
1.400 parts by mass Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide 0.200 parts by mass The following commercially available products were used.
2,4-Bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine: "Tinosorb (registered trademark) S" (manufactured by BASF Japan Ltd.)
Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide: "Omnirad (registered trademark) 819" (having an absorption band in the wavelength range of 200 to 450 nm, manufactured by IGM Resins B.V.)

(3.1.2) Formation of adhesive layer 1 The obtained ultraviolet-curable acrylic adhesive composition (a-1) was applied onto the surface of a release film so that the thickness after curing was 25 μm, and a release film was then attached to the surface. Thereafter, ultraviolet light was irradiated under conditions of illuminance: 6.5 mW/cm ² and cumulative light amount: 1500 mJ/cm ² to cure the composition, and the release film was peeled off to form adhesive layer 1.

(4) Preparation of Laminate Two types of two-layer films obtained by preparing a cured layer on a resin layer were combined as shown in the table, and laminated together via the adhesive layer to prepare a laminate. The layers were laminated together in the following order: first cured layer, first resin layer, first adhesive layer, second cured layer, and second resin layer.

(5) Preparation of Glass Layer (Thin Glass) (5.1) Preparation of Glass Layer 1 A glass layer (soda lime glass) having a size of 12 inches was prepared according to the following steps.

(Step 1) A thin film glass was prepared so that a first surface of the thin film glass was in contact with a carrier substrate having a bonding surface. Then, a contact film having adhesive force was attached to a second surface of the thin film glass opposite to the first surface.
(Step 2) The thin glass was then peeled off from the carrier substrate by the highly adhesive contact film.
(Step 3) The contact film was removed from the second surface of the thin glass peeled off from the carrier substrate by a weakening treatment (electromagnetic radiation exposure) that weakened the adhesive strength of the contact film.

In step 1, a thin glass film was prepared so as to be in contact with a carrier substrate having a thickness of 500 μm and to have a predetermined thickness, and then a contact film was attached to the thin glass film. Next, in step 2, the thin glass film together with the contact film was peeled off from the carrier substrate in 30 seconds.
The contact film used was a commercially available product, "NDS4150-20.""NDS4150-20" is a 150 μm thick film containing polyolefin (PO), and further has a 10 μm thick adhesive layer.

Next, in step 3, the exposed contact film was subjected to a weakening treatment to reduce the adhesive strength. In the weakening treatment, ultraviolet light with a wavelength of 365 nm was irradiated onto the contact film for 10 seconds. The illuminance of the ultraviolet light was 500 mW/ ^cm2 , and the cumulative amount of light was 500 mJ/ ^cm2 . The adhesive strength before the weakening treatment was 11 N/25 mm, but after the weakening treatment, the adhesive strength was reduced to 0.4 N/25 mm. This allowed the contact film to be easily peeled off from the thin glass, and a glass layer with a thickness of 30 μm was obtained.

(5.2) Preparation of Glass Layer 2 Glass layer 2 was prepared in the same manner as in the preparation of glass layer 1, except that the thickness was changed to 10 μm.

(6) Preparation of a laminate having a glass layer The laminate and the glass layer were laminated together via the adhesive layer to prepare a laminate having a glass layer. The layers were laminated together in the following order: first cured layer, first resin layer, first adhesive layer, second cured layer, second resin layer, second adhesive layer, and glass layer.

The structures of the resulting laminates are shown in Tables I to III below.
In the table, "-" indicates that the corresponding layer is not present or that the corresponding component is not contained.
The "wavelength" in the table indicates the maximum absorption wavelength in the ultraviolet-visible light absorption spectrum of the dye compound in the wavelength region of 300 to 460 nm.
In the table, "content" indicates the content of the dye compound relative to the total mass of the resin. Note that, for the resin layer 14, the total mass of the thermoplastic (meth)acrylic resin and the rubber particles was taken as the total mass of the resin.

2. Method for measuring physical properties of resin layer (average light transmittance of first resin layer)
The resin layer was conditioned for 24 hours in an air-conditioned room at a temperature of 23° C. and a relative humidity of 55 RH. Then, in accordance with JIS K-7375:2008, the light transmittance was measured using a UV-2450 UV-visible spectrophotometer (manufactured by Shimadzu Corporation), and the arithmetic average value was calculated in the wavelength region of 450 to 800 nm.

(Storage Modulus of First Resin Layer and Second Resin Layer)
The storage modulus of each resin layer at 25° C. was measured using a rheometer device “RSA-3” (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
Test conditions (dynamic viscoelasticity test)
Testing machine: Dynamic viscoelasticity measuring device "RSA-3" (manufactured by TA Instruments Japan, Inc.)
Deformation method: tension Preload load: 55g
Temperature range: -70 to 200°C
Frequency: 1.0Hz
Displacement: ±0.1%
Sample: Width 5mm
Chuck distance: 20 mm

The following Table IV shows the measurement results of the physical properties of the first resin layer and the second resin layer in each laminate.
In the table, "Average light transmittance from 450 to 800 nm" indicates the arithmetic mean value of the light transmittance in the wavelength region from 450 to 800 nm.
In the table, "Elastic modulus 2/Elastic modulus 1" represents a value expressed by "storage modulus 2 of the second resin layer/storage modulus 1 of the first resin layer", i.e., the ratio of the storage modulus at 25°C of the second resin layer to that of the first resin layer.

3. Evaluation Each of the obtained laminates was evaluated as follows.

(1) Light resistance The glass layer of each laminate obtained above and the viewing side of the display device obtained by laminating the organic EL layer were bonded together via a third adhesive layer. For laminates not having a glass layer, the second resin layer and the viewing side of the display device obtained by laminating the organic EL layer were bonded together via a third adhesive layer. This display device was continuously irradiated with light from a xenon lamp (60 W/m ² ) from the viewing side for 100 hours. Thereafter, a black image was displayed. Then, the front reflectance was measured using a spectrophotometer "CM-2600d" (manufactured by Konica Minolta, Inc.), and the front reflectance was evaluated according to the following criteria. It should be noted that if the evaluation is A or higher (AAA to A), it is practical.

AAA: 1.5 or less.
AA: greater than 1.5 and equal to or less than 1.6.
A: More than 1.6 and 1.7 or less.
B: More than 1.7 and 1.8 or less.
C: greater than 1.8.

(2) Pen drop test (impact resistance)
An organic EL layer was laminated on the glass layer of each laminate obtained above, and the first cured layer was arranged to be the uppermost part, to obtain a display device. For the laminate not having a glass layer, an organic EL layer was laminated on the second resin layer, and the first cured layer was arranged to be the uppermost part, to obtain a display device. A ballpoint pen with a pen tip radius (R) of 0.35 mm and a weight (m) of 12 g was dropped on the surface of the first cured layer of each display device while changing the drop height. A black image was displayed on each display device after the pen drop test. Then, the front reflectance was measured using a spectrophotometer "CM-2600d" (manufactured by Konica Minolta, Inc.) and evaluated according to the following criteria. It should be noted that if the evaluation is A or higher (AAA to A), it is practical.

AAA: 1.5 or less.
AA: greater than 1.5 and equal to or less than 1.6.
A: More than 1.6 and 1.7 or less.
B: More than 1.7 and 1.8 or less.
C: greater than 1.8.

　Table V below shows the evaluation results for each laminate.

From the Examples and Comparative Examples, it is apparent that the laminate of the present invention can achieve both light resistance and impact resistance.
From a comparison of Examples 1 to 5, it is apparent that the first resin layer containing cellulose ester can achieve both light resistance and impact resistance.

From Examples 8 and 14, it is seen that the light transmittance of the resin layer can be adjusted to a desired value by using a dye compound having a structure represented by the above general formula (1).
From Examples 1 and 11 to 13, it is seen that the light transmittance of the resin layer can be adjusted to a desired value by using a dye compound having a structure represented by the above general formula (2).

Examples 8 and 9 show that light resistance and impact resistance can be achieved together when the glass layer thickness is in the range of 10 to 30 μm.

By using this invention, it is possible to provide a display device that is both light-resistant and impact-resistant.

REFERENCE SIGNS LIST 1 First cured layer 2 First resin layer 3 First adhesive layer 4 Second cured layer 5 Second resin layer 6 Glass layer 7 Second adhesive layer 8 Third adhesive layer 9 Organic EL layer 10 Laminate 11 Laminate 12 Laminate 21 Carrier substrate 22 Thin glass 23 Contact film 24 Electromagnetic radiation 100 Display device

Claims (12)

A laminate having a resin layer, a cured layer, and an adhesive layer,
A first cured layer, a first resin layer, a first adhesive layer, a second cured layer, and a second resin layer are laminated in this order,
the first resin layer contains a dye compound having a maximum absorption wavelength in the range of 360 to 379 nm in an ultraviolet-visible light absorption spectrum in a wavelength region of 300 to 460 nm,
The first resin layer has an average light transmittance of 87% or more in a wavelength range of 450 to 800 nm;
The storage modulus of the first resin layer at 25° C. is within a range of 4.0 to 8.0 GPa,
a ratio of a storage modulus at 25° C. of the second resin layer to that of the first resin layer is within a range of 0.7 to 1.5. The laminate according to claim 1 , wherein the first resin layer contains a cellulose ester. The laminate according to claim 1 , wherein the dye compound has a structure represented by the following general formula (1):

(In the formula, R ₁₁ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a hydroxy group, an amino group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group. R ₁₂ represents a hydrogen atom or a hydroxy group.) The laminate according to claim 1 , wherein the dye compound has a structure represented by the following general formula (2):

(In the formula, R ₂₁ represents a hydrogen atom or a hydroxy group. R ₂₂ , R ₂₃ , and R ₂₄ represent an alkyl group, an alkoxy group, an alkyl-substituted amino group, a carboxy group, an alkyloxycarbonyl group, a hydroxyalkyl group, an alkylcarbonyloxyalkyl group, a carboxyalkyl group, an alkyloxycarbonylalkyl group, an aryl group, an acyl group, or a sulfo group.) 2. The laminate according to claim 1, wherein the first resin layer has a thickness in the range of 15 to 50 μm. 2. The laminate according to claim 1, wherein the second resin layer has a storage modulus at 25° C. in the range of 4.0 to 8.0 GPa. Further comprising a glass layer,
The laminate according to any one of claims 1 to 6, wherein the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, and the glass layer are laminated in this order. Further comprising a second adhesive layer,
The laminate according to claim 7 , wherein the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, the second adhesive layer, and the glass layer are laminated in this order. 8. The laminate according to claim 7, wherein the glass layer has a thickness in the range of 10 to 30 μm. Further comprising a third adhesive layer,
The laminate according to claim 8 , wherein the first cured layer, the first resin layer, the first adhesive layer, the second cured layer, the second resin layer, the second adhesive layer, the glass layer, and the third adhesive layer are laminated in this order. A display device comprising the laminate according to claim 10. The display device according to claim 11 , wherein the first resin layer of the laminate is disposed on a viewing side of the display device relative to the second resin layer.

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