CN114829995A - Composite polarizing plate and liquid crystal display device - Google Patents

Abstract

The invention aims to provide a composite polarizing plate capable of inhibiting appearance defects in a high-temperature durability test and a liquid crystal display device using the composite polarizing plate. The composite polarizing plate comprises a polarizing plate having a protective layer on at least one surface of a linear polarizing layer, and a brightness enhancement film, wherein a1 st adhesive layer, a buffer layer, and a brightness enhancement film are sequentially laminated on the protective layer side of the polarizing plate. The buffer layer has a tensile modulus of 1.5GPa or more at a temperature of 23 ℃ and a relative humidity of 55%.

Description

Composite polarizing plate and liquid crystal display device

Technical Field

The present invention relates to a composite polarizing plate and a liquid crystal display device using the same.

Background

Conventionally, it is known that the brightness of a liquid crystal display device is improved by using a composite polarizing plate in which a polarizing plate and a brightness enhancement film are laminated (patent documents 1 to 5). In recent years, as mobile terminals such as smartphones have been increased in size, brightness enhancement films have been used to improve the light utilization efficiency in order to realize long-term driving with a limited battery capacity.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 11-248941

Patent document 2: japanese laid-open patent publication No. 11-248942

Patent document 3: japanese laid-open patent publication No. 11-64840

Patent document 4: japanese laid-open patent publication No. 11-64841

Patent document 5: japanese patent No. 4880719

Disclosure of Invention

Problems to be solved by the invention

When the composite polarizing plate as described above was subjected to a high-temperature durability test, it was found that wrinkles were generated in the brightness enhancement film, and appearance defects were generated in the composite polarizing plate. When the composite polarizing plate is applied to a liquid crystal display device, such appearance defects cause visibility to be reduced.

The invention aims to provide a composite polarizing plate capable of inhibiting appearance defects in a high-temperature durability test and a liquid crystal display device using the composite polarizing plate.

Means for solving the problems

The invention provides the following composite polarizing plate and liquid crystal display device.

[ 1] A composite polarizing plate comprising a polarizing plate having a protective layer on at least one surface of a linear polarizing layer and a brightness enhancing film,

a1 st adhesive layer, a buffer layer, and the brightness enhancement film are sequentially laminated on the protective layer side of the polarizing plate,

the buffer layer has a tensile elastic modulus of 1.5GPa or more at a temperature of 23 ℃ and a relative humidity of 55%.

The composite polarizing plate according to [ 1], wherein the buffer layer and the brightness enhancement film are bonded to each other through a2 nd adhesive layer.

The composite polarizing plate according to [ 1] or [ 2], wherein the buffer layer is a resin film.

The composite polarizing plate according to [ 3], wherein the resin film comprises a film comprising at least 1 resin selected from a cellulose ester resin, a (meth) acrylic resin, and a cycloolefin resin.

The composite polarizing plate according to [ 1], wherein the buffer layer is in direct contact with the brightness enhancement film.

The composite polarizing plate according to [ 1] or [ 5], wherein the buffer layer is a cured product layer of a resin composition containing a curable component.

The composite polarizing plate according to [ 6 ], wherein the curable component comprises an active energy ray-curable compound.

The composite polarizing plate according to any one of [ 1] to [ 7 ], wherein an in-plane retardation Re (590) of the buffer layer at a wavelength of 590nm is 20nm or less.

The composite polarizing plate according to any one of [ 1] to [ 8 ], wherein the 1 st adhesive layer bonds the protective layer and the buffer layer of the polarizing plate.

The composite polarizing plate according to any one of [ 1] to [ 9 ], wherein the polarizing plate has the protective layer on both surfaces of the linear polarizing layer.

The composite polarizing plate according to any one of [ 1] to [ 10 ], wherein a3 rd adhesive layer is provided on a side of the polarizing plate opposite to the brightness enhancement film side.

The composite polarizing plate according to [ 11 ], wherein a release film is provided on a side of the 3 rd adhesive layer opposite to the polarizing plate side.

A liquid crystal display device comprising the composite polarizing plate according to any one of [ 1] to [ 12 ] and a liquid crystal cell.

[ 14 ] the liquid crystal display device according to [ 13 ], further comprising a backlight,

the composite polarizing plate is disposed between the liquid crystal cell and the backlight such that the brightness enhancement film side is the backlight side.

Effects of the invention

According to the present invention, a composite polarizing plate in which appearance defects are suppressed in a high-temperature durability test, and a display device using the composite polarizing plate can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view schematically showing an example of the composite polarizing plate of the present invention.

Fig. 2 is a schematic cross-sectional view schematically showing another example of the composite polarizing plate of the present invention.

Fig. 3 is a schematic cross-sectional view schematically showing still another example of the composite polarizing plate of the present invention.

Fig. 4 is a schematic cross-sectional view schematically showing still another example of the composite polarizing plate of the present invention.

Fig. 5 is a schematic cross-sectional view schematically showing an example of a liquid crystal display device of the present invention.

Fig. 6 is a schematic cross-sectional view schematically showing another example of the liquid crystal display device of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the composite polarizing plate of the present invention and a liquid crystal display device using the same will be described with reference to the drawings.

< composite polarizing plate >

The composite polarizing plate of the present invention is a composite polarizing plate comprising a polarizing plate having a protective layer on at least one side of a linear polarizing layer and a brightness enhancement film,

a1 st adhesive layer, a buffer layer, and a brightness enhancement film are laminated in this order on the protective layer side of a polarizing plate,

the buffer layer has a tensile modulus of 1.5GPa or more at a temperature of 23 ℃ and a relative humidity of 55%.

The brightness enhancement film can reflect linearly polarized light having a predetermined polarization axis or circularly polarized light having a predetermined direction among incident light such as natural light, and transmit other light. Therefore, in a composite polarizing plate in which a brightness enhancement film and a polarizing plate including a linearly polarizing layer are laminated, light from a light source such as a backlight of a liquid crystal display device or the like is incident to obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state can be reflected without being transmitted. When a composite polarizing plate having a brightness enhancement film and a linear polarizing layer is used in a liquid crystal display device, light reflected on the brightness enhancement film surface is inverted by a reflecting layer or the like provided on the rear side thereof, and then incident on the brightness enhancement film again, and a part or the whole of the light is transmitted as light in a predetermined polarization state, whereby the amount of light transmitted through the brightness enhancement film can be increased. Further, by supplying the polarized light which is not easily absorbed by the linear polarization layer to the polarization plate, the amount of light which can be used for image display and the like can be increased, and the luminance of the liquid crystal display device can be improved.

In this way, the brightness enhancement film repeats the operation of reflecting light having a polarization direction absorbed by the linear polarization layer from the brightness enhancement film without being incident on the linear polarization layer, and then inverting the reflected light by a reflection layer or the like provided on the rear side of the brightness enhancement film, and then re-incident on the brightness enhancement film. Thus, only the polarized light transmitting brightness enhancement film having a polarization direction that can pass through the linearly polarizing layer among the light reflected and inverted between the linearly polarizing layer and the brightness enhancement film can supply the transmitted light to the linearly polarizing layer. Therefore, by using the composite polarizing plate including the brightness enhancement film and the polarizing plate as described above, light such as backlight can be effectively used for image display of a liquid crystal display device in the liquid crystal display device or the like, and the screen can be bright.

As described later, the buffer layer included in the composite polarizing plate may be a resin film or a cured product layer of a resin composition containing a curable component. The tensile modulus of the cushion layer may be 3GPa or more, or 5GPa or more, usually 10GPa or less, or 8GPa or less. The tensile modulus can be measured by the method described in examples described later. The tensile modulus of elasticity when the buffer layer is a cured layer can be measured by the following procedure. The release-treated surface of the polyethylene terephthalate film (hereinafter, sometimes referred to as "PET film") subjected to release treatment was coated with a resin composition using a coater so that the thickness after drying was 100 μm. Thereafter, the resin composition was placed in an atmosphere at room temperature for 30 minutes to be pre-dried, and further placed at 100 ℃ for 5 minutes to be main-dried, whereby the solvent contained in the resin composition applied to the PET film was sufficiently volatilized. Finally, a predetermined curing treatment (heating treatment, ultraviolet irradiation treatment, or the like) is performed to prepare a cured product layer on the PET film, and the PET film is peeled off, and the tensile modulus of elasticity is measured by the method described in the examples described below using the obtained cured product layer as a sample for measurement.

It has been ascertained that wrinkles generated in the brightness enhancement film after the high temperature durability test are generated due to shrinkage of the polarizing plate in a high temperature environment. The composite polarizing plate of the present embodiment has a buffer layer interposed between the polarizing plate and the brightness enhancement film. Since the buffer layer has a tensile elastic modulus in the above range, it is not easily deformed. Therefore, even if the polarizing plate shrinks in the high-temperature durability test of the composite polarizing plate, the shrinkage of the brightness enhancement film caused by the shrinkage of the polarizing plate can be suppressed because the buffer layer which is not easily deformed exists between the polarizing plate and the brightness enhancement film. This can prevent wrinkles from occurring at the end of the brightness enhancement film, and can prevent appearance defects from occurring in the composite polarizing plate subjected to the high-temperature durability test. In addition, when the composite polarizing plate is applied to a liquid crystal display device, it is possible to suppress a decrease in visibility of an image displayed on a screen of the liquid crystal display device.

The in-plane retardation Re (590) of the buffer layer at a wavelength of 590nm is preferably 20nm or less, may be 10nm or less, may be 5nm or less, and may be 0 nm. When Re (590) of the buffer layer is in the above range, the reduction in viewing angle characteristics when the composite polarizing plate is applied to a liquid crystal display device can be suppressed. The in-plane retardation Re (590) can be measured by the method described in the examples described later. The in-plane retardation Re (590) when the buffer layer is a cured layer may be measured by preparing a sample for measurement according to the procedure for preparing a sample for measurement used for measuring the tensile elastic modulus when the buffer layer is a cured layer, and measuring the sample for measurement by the method described in the examples described later, except that the thickness after drying is set to the actual thickness of the buffer layer included in the composite polarizing plate.

The 1 st adhesive layer is preferably an adhesive layer for bonding the protective layer and the buffer layer of the polarizing plate. In this case, the 1 st adhesive layer is provided so as to be in direct contact with both the protective layer and the buffer layer of the polarizing plate.

Hereinafter, embodiments of the composite polarizing plate will be specifically described.

[ embodiment mode 1]

Fig. 1 and 2 are schematic cross-sectional views schematically showing an example of the composite polarizing plate of the present embodiment. In the composite polarizing plate 1 of the present embodiment, a polarizing plate 10, a1 st adhesive layer 31, a buffer layer 15a, a2 nd adhesive layer 32, and a brightness enhancement film 18 are stacked in this order. The 2 nd adhesive layer 32 is an adhesive layer for bonding the buffer layer 15a and the brightness enhancement film 18, and the 2 nd adhesive layer 32 is provided so as to be in contact with both the buffer layer 15a and the brightness enhancement film 18.

The polarizing plate 10 shown in fig. 1 and 2 includes a1 st protective layer 12 disposed on the side of the linear polarizing layer 11 facing the brightness enhancement film 18, and a2 nd protective layer 13 disposed on the side of the linear polarizing layer 11 opposite to the side facing the brightness enhancement film 18. The polarizing plate 10 may be a polarizing plate having the 1 st protective layer 12 and not having the 2 nd protective layer 13.

Composite polarizer 1 may have a3 rd adhesive layer 33 on the side of polarizer 10 opposite the side of brightness enhancement film 18 as shown in fig. 2. The 3 rd adhesive layer 33 can be used for bonding the composite polarizing plate 1 to a liquid crystal cell in a liquid crystal display device described later. The composite polarizing plate 1 may further have a release film 35 (fig. 2) for coating and protecting the surface of the 3 rd adhesive layer 33 on the side of the 3 rd adhesive layer 33 opposite to the polarizing plate 10 side.

The buffer layer 15a provided on the composite polarizing plate 1 is preferably a resin film. The resin film is preferably formed of a resin material having excellent transparency, mechanical strength, thermal stability, water resistance, stability of a phase difference value, and the like, and the resin material is preferably a thermoplastic resin. The resin film may have a single-layer structure or a multilayer structure. The resin film may be a stretched film. For example, the tensile elastic modulus can be adjusted by selecting the kind of resin constituting the resin film, stretching the resin film, or the like. The details of the resin (resin material) for forming the resin film constituting the cushion layer 15a will be described later, but it is preferable to use a film formed of at least 1 resin selected from cellulose ester-based resins, (meth) acrylic resins, and cycloolefin-based resins.

The composite polarizing plate 1 can be obtained by bonding the 1 st protective layer 12 side of the polarizing plate 10 and the buffer layer 15a with the 1 st adhesive layer 31 and bonding the buffer layer 15a and the brightness enhancement film 18 with the 2 nd adhesive layer 32. When the composite polarizing plate 1 has the 3 rd adhesive layer 33, for example, an adhesive sheet having the 3 rd adhesive layer 33 formed on the release film 35 may be laminated on the polarizing plate 10.

[ embodiment 2]

Fig. 3 and 4 are schematic cross-sectional views schematically showing another example of the composite polarizing plate according to the present embodiment. In the composite polarizing plate 2 of the present embodiment, a polarizing plate 10, a1 st adhesive layer 31, a buffer layer 15b, and a brightness enhancement film 18 are sequentially stacked. The polarizing plate 10 shown in fig. 3 and 4 includes a1 st protective layer 12 disposed on the side of the linear polarizing layer 11 facing the brightness enhancement film 18, and a2 nd protective layer 13 disposed on the side of the linear polarizing layer 11 opposite to the side facing the brightness enhancement film 18. The polarizing plate 10 may be a polarizing plate having the 1 st protective layer 12 and not having the 2 nd protective layer 13.

The composite polarizing plate 2 may have a3 rd adhesive layer 33 and a release film 35 in this order on the side opposite to the side of the brightness enhancement film 18 of the polarizing plate 10, as described in the composite polarizing plate 1 shown in fig. 2 (fig. 4).

The buffer layer 15b provided in the composite polarizing plate 2 is provided so as to directly contact the brightness enhancement film 18 without interposing another layer such as an adhesive layer. The buffer layer 15b is preferably a cured product layer of a resin composition containing a curable component. The buffer layer 15b as a cured product layer can be formed by, for example, applying the above resin composition to one surface of the brightness enhancement film 18 and curing the curable component. The buffer layer 15b as the cured product layer can be adjusted to have a tensile elastic modulus within the above range by selecting the type of the curable component, for example. The curable component constituting the buffer layer 15b will be described in detail later, but more preferably is a cured layer of a resin composition containing an active energy ray-curable compound as the curable component.

The composite polarizing plate 2 can be obtained by bonding the buffer layer 15b side of the laminate having the buffer layer 15b formed on the brightness enhancement film 18 and the 1 st protective layer 12 side of the polarizing plate 10 with the 1 st adhesive layer 31. In the case where the composite polarizing plate 2 has the 3 rd adhesive layer 33, the 3 rd adhesive layer 33 may be provided, for example, by the method described in the case where the 3 rd adhesive layer 33 is provided in the composite polarizing plate 1.

< liquid Crystal display device >

Fig. 5 and 6 are schematic cross-sectional views schematically showing an example of the liquid crystal display device of the present embodiment. The liquid crystal display devices 5 and 6 of the present embodiment include the composite polarizing plate 1 or the composite polarizing plate 2 described above, and a liquid crystal cell 41, and usually further include a backlight 42. The composite polarizing plates 1 and 2 are preferably provided on the backlight 42 side (the side opposite to the visible side) of the liquid crystal cell 41. In this case, as shown in fig. 5 and 6, the composite polarizing plates 1 and 2 are preferably laminated on the liquid crystal cell 41 through the 3 rd adhesive layer 33 provided on the polarizing plate 10 side so that the brightness enhancement film 18 side is disposed on the backlight 42 side.

In the liquid crystal display devices 5 and 6 having the composite polarizing plate 1 or the composite polarizing plate 2, since the composite polarizing plates 1 and 2 include the brightness enhancement film 18 as described above, the light of the backlight 42 can be efficiently used for image display of the liquid crystal display devices 5 and 6, and the screen can be bright.

Since the composite polarizing plates 1 and 2 each have the buffer layers 15a and 15b having the tensile elastic modulus described above, appearance defects are less likely to occur when a high-temperature durability test is performed. Thus, the liquid crystal display devices 5 and 6 having the composite polarizing plate 1 or the composite polarizing plate 2 can suppress a reduction in visibility even when exposed to a high temperature condition.

The following describes the details of the respective members forming the composite polarizing plate and the liquid crystal display device.

[ buffer layer ]

The buffer layer is a layer having a tensile elastic modulus in the above range. The buffer layer preferably has an in-plane retardation Re (590) in the above range. The buffer layer may be a resin film or a cured layer of a resin composition containing a curable component.

The thickness of the buffer layer is preferably 20 μm or more, more preferably 25 μm or more, further preferably 30 μm or more, and usually 80 μm or less, and may be 70 μm or less, and may be 60 μm or less.

[ resin film constituting buffer layer ]

When the cushion layer is a resin film, the resin material (resin) constituting the resin film is preferably a resin material having excellent transparency, mechanical strength, thermal stability, water resistance, stability of a phase difference value, and the like. The resin material is preferably a thermoplastic resin. Such a resin material is not particularly limited, and examples thereof include cellulose ester resins; (meth) acrylic resins; olefin resins such as chain aliphatic olefin resins and cyclic olefin resins; a polyvinyl chloride resin; a styrene resin; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resin; a polyvinylidene chloride resin; a polyamide resin; a polyacetal resin; a polycarbonate-based resin; modified polyphenylene ether resin; polyester resins such as polybutylene terephthalate resins and polyethylene terephthalate resins; a polysulfone-based resin; a polyether sulfone-based resin; a polyarylate-based resin; a polyamide imide resin; polyimide resins and the like, and 1 or a combination of two or more of them may be used. Among them, a resin selected from cellulose ester resins, (meth) acrylic resins, and cycloolefin resins is preferably used. In the present specification, "(meth) acrylic" means any of acrylic and methacrylic. The same applies to "(meth)" such as (meth) acryloyl group.

The resin material constituting the resin film may be used after optionally performing appropriate polymer modification, and examples of the polymer modification include modification such as copolymerization, crosslinking, molecular terminal, stereoregularity control, and mixing involving a reaction between different polymers.

The cellulose ester resin is a cellulose organic acid ester or a cellulose mixed organic acid ester in which a part or all of hydrogen atoms of hydroxyl groups of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (hardwood pulp and softwood pulp) is substituted with acetyl, propionyl and/or butyryl groups. Examples of the resin include cellulose acetate, cellulose propionate, cellulose butyrate, and mixed esters thereof. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, and the like are preferable.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of the (meth) acrylic resin include poly (meth) acrylates such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylate copolymers; methyl methacrylate-acrylate- (meth) acrylic acid copolymer; methyl (meth) acrylate-styrene copolymers (MS resins and the like); and copolymers of a compound having an alicyclic hydrocarbon group and methyl methacrylate such as a methyl methacrylate-cyclohexyl methacrylate copolymer and a methyl methacrylate- (norbornyl meth) acrylate copolymer. Preferably, a poly (meth) acrylic acid C such as poly (methyl (meth) acrylate) is used _1-6 The polymer containing an alkyl ester as a main component is preferably a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

The (meth) acrylic resin may have a structural unit exhibiting positive birefringence. When the structural unit exhibiting positive birefringence and the structural unit exhibiting negative birefringence are present, the retardation of the film made of the (meth) acrylic resin can be controlled by adjusting the presence ratio thereof, and a (meth) acrylic resin film having a low retardation can be obtained. Examples of the structural unit exhibiting positive birefringence include a lactone ring, a structural unit constituting polycarbonate, polyvinyl alcohol, cellulose acetate, polyester, polyarylate, polyimide, polyolefin, and the like, and a structural unit represented by the general formula (1) described later. Examples of the structural unit exhibiting negative birefringence include structural units derived from styrene monomers, maleimide monomers, and the like, structural units of polymethyl methacrylate, structural units represented by the general formula (3) described later, and the like.

As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure or a glutarimide structure is preferably used. The (meth) acrylic resin having a lactone ring structure or a glutarimide structure is excellent in heat resistance. More preferably a (meth) acrylic resin having a glutarimide structure. When a (meth) acrylic resin having a glutarimide structure is used, a (meth) acrylic resin film having low moisture permeability and small retardation and ultraviolet transmittance can be obtained. (meth) acrylic resins having a glutarimide structure (hereinafter also referred to as "glutarimide resins") are described in, for example, Japanese patent application laid-open Nos. 2006-. These descriptions are incorporated herein by reference.

The glutarimide resin preferably contains a structural unit represented by the following general formula (1) (hereinafter also referred to as a "glutarimide unit") and a structural unit represented by the following general formula (2) (hereinafter also referred to as a "(meth) acrylate unit").

[ solution 1]

[ in the general formula (1), R ¹ And R ² Each independently hydrogen or C1-C8 alkyl, R ³ Is hydrogen, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 3 to 12 carbon atoms, or substituent group having 5 to 15 carbon atoms and containing aromatic ring.

In the general formula (2), R ⁴ And R ⁵ Each independently hydrogen or C1-C8 alkyl, R ⁶ Is hydrogen, alkyl group having 1 to 18 carbon atoms, cycloalkyl group having 3 to 12 carbon atoms, or substituent group having 5 to 15 carbon atoms and containing aromatic ring.]

The glutarimide resin may further contain a structural unit represented by the following general formula (3) (hereinafter also referred to as "aromatic vinyl unit") as necessary.

[ solution 2]

[ in the general formula (3), R ⁷ Is hydrogen or C1-8 alkyl, R ⁸ Aryl with 6-10 carbon atoms]。

In the above general formula (1), R is preferably ¹ And R ² Each independently is hydrogen or methyl, R ³ Is hydrogen, methyl, butyl, or cyclohexyl, more preferably R ¹ Is methyl, R ² Is hydrogen, R ³ Is methyl.

The glutarimide resin may contain only a single type of glutarimide unit, or may contain R in the general formula (1) ¹ 、R ² And R ³ A plurality of different categories.

The glutarimide unit can be formed by imidizing the (meth) acrylate unit represented by the above general formula (2). Alternatively, the glutarimide unit may be prepared by reacting an acid anhydride such as maleic anhydride or a half ester of such an acid anhydride with a linear or branched alcohol having 1 to 20 carbon atoms; and α, β -ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, fumaric acid, and citraconic acid.

In the above general formula (2), R is preferably ⁴ And R ⁵ Each independently is hydrogen or methyl, R ⁶ Is hydrogen or methyl, more preferably R ⁴ Is hydrogen, R ⁵ Is methyl, R ⁶ Is methyl.

In the glutarimide resin, the (meth) acrylate unit may be contained only in a single kind, or may be contained in R in the general formula (2) ⁴ 、R ⁵ And R ⁶ A plurality of different categories.

In the glutarimide resin, the aromatic vinyl unit represented by the above general formula (3) preferably contains styrene, α -methylstyrene, or the like, and more preferably contains styrene. By using such a glutarimide resin having an aromatic vinyl unit, the positive birefringence of the glutarimide structure can be reduced, and a (meth) acrylic resin film having a lower retardation can be obtained.

In the glutarimide resin, the aromatic vinyl unit may be contained only in a single kind, or R in the above general formula (3) may be contained ⁷ And R ⁸ A plurality of different categories.

The content of glutarimide units in the glutarimide resin is preferably such as to be in accordance with R ³ And the like. The content of the glutarimide unit is preferably 1 to 80% by weight, more preferably 1 to 70% by weight, still more preferably 1 to 60% by weight, and particularly preferably 1 to 50% by weight, based on the total structural units of the glutarimide resin. When the content of the glutarimide unit is in such a range, a (meth) acrylic resin film having a low retardation and excellent heat resistance can be obtained.

The content of the aromatic vinyl unit in the glutarimide resin can be appropriately set according to the purpose and the required properties. The content of the aromatic vinyl unit may be 0 depending on the use. When the aromatic vinyl unit is contained, the content thereof is preferably 10 to 80% by weight, more preferably 20 to 80% by weight, further preferably 20 to 60% by weight, and particularly preferably 20 to 50% by weight, based on the glutarimide unit of the glutarimide resin. When the content of the aromatic vinyl unit is in such a range, a (meth) acrylic resin film having a low phase difference and excellent heat resistance and mechanical strength can be obtained.

In the glutarimide resin, if necessary, other structural units than the glutarimide unit, (meth) acrylate unit, and aromatic vinyl unit may be further copolymerized. Examples of the other structural units include nitrile monomers such as acrylonitrile and methacrylonitrile; and a structural unit composed of a maleimide monomer such as maleimide, N-methylmaleimide, N-phenylmaleimide, or N-cyclohexylmaleimide. These other structural units may be directly copolymerized or graft-copolymerized in the glutarimide resin.

The olefin-based resin is a resin containing a constituent unit derived from a linear aliphatic olefin such as ethylene and propylene, or an alicyclic olefin such as norbornene and a substitute thereof (hereinafter, these are also collectively referred to as a norbornene-based monomer). The olefin resin may be a copolymer using 2 or more kinds of monomers.

As the olefin-based resin, a cyclic olefin-based resin that is a resin mainly containing a constituent unit derived from an alicyclic olefin is preferably used. Typical examples of the alicyclic olefin constituting the cycloolefin resin include norbornene monomers. Norbornene is a compound in which the 1 carbon-carbon bond of norbornane is changed to a double bond, and is named bicyclo [2, 2, 1] hept-2-ene according to IUPAC nomenclature. Examples of the substituent of norbornene include a 3-substituent, a 4-substituent, and a 4, 5-disubstituted compound in which the position of the double bond of norbornene is 1, 2-position, and dicyclopentadiene (Japanese patent: ジシクロペンタジエン), dimethanonaphthalene and the like.

The cycloolefin-based resin may or may not have a norbornane ring in its constituent unit. Examples of the norbornene-based monomer forming the cycloolefin-based resin having no norbornane ring in the constituent unit include monomers which become five-membered rings by ring opening, and representative examples thereof include norbornene, dicyclopentadiene, 1-or 4-methylnorbornene, and 4-phenylnorbornene. When the cycloolefin-based resin is a copolymer, the arrangement state of the molecules is not particularly limited, and the cycloolefin-based resin may be a random copolymer, a block copolymer, or a graft copolymer.

More specific examples of the cycloolefin-based resin include ring-opened polymers of norbornene-based monomers, ring-opened copolymers of norbornene-based monomers and other monomers, modified polymers obtained by addition of maleic acid, addition of cyclopentadiene, and the like to the above-mentioned monomers, and polymers or copolymers obtained by hydrogenation of the above-mentioned monomers; addition polymers of norbornene monomers, and addition copolymers of norbornene monomers and other monomers. Examples of other monomers for preparing the copolymer include α -olefins, cycloolefins, and non-conjugated dienes. The cycloolefin resin may be a copolymer of 1 or 2 or more species using a norbornene monomer and another alicyclic olefin.

As the cycloolefin-based resin, a resin obtained by hydrogenating a ring-opened polymer or a ring-opened copolymer using a norbornene-based monomer is preferably used.

The resin material constituting the resin film may contain an appropriate additive in a range not to impair transparency. Examples of the additives include antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, retardation reducing agents, stabilizers, processing aids, plasticizers, impact resistance aids, delustering agents, antibacterial agents, and antifungal agents. These additives may be used in combination.

As a method for producing a resin film using the above resin material, an optional optimum method can be appropriately selected. Examples thereof include a solvent casting method in which a resin dissolved in a solvent is cast on a metal belt or drum, and the solvent is dried and removed to obtain a film; a melt extrusion method in which a resin is heated to a temperature equal to or higher than its melting temperature and kneaded, and then extruded from a die and cooled to obtain a film. In the melt extrusion method, a single layer film may be extruded, or a multilayer film may be extruded at the same time.

As described above, the resin film may be a stretched film subjected to stretching.

The tensile modulus of elasticity can be adjusted to a desired range by performing a stretching process. Examples of the stretching treatment include uniaxial stretching and biaxial stretching.

[ cured product layer of resin composition containing curable component constituting buffer layer ]

When the buffer layer is a cured product layer of a resin composition containing a curable component, the curable component contained in the resin composition is preferably an active energy ray-curable compound that is cured by irradiation with an active energy ray or a thermosetting cured product that is cured by heating. The curable component is more preferably an active energy ray-curable compound.

[ A ] A resin composition comprising an active energy ray-curable compound

Examples of the active energy ray-curable compound include an electron beam-curable compound, an ultraviolet-curable compound, and a visible light-curable compound. Among them, ultraviolet-curable compounds or visible light-curable compounds are preferable, and ultraviolet-curable compounds are more preferable. The resin composition containing the ultraviolet-curable compound or the visible light-curable compound may be a radical polymerization type resin composition or a cationic polymerization type resin composition. In the present specification, the term "ultraviolet ray" refers to an active energy ray having a wavelength of 10nm or more and less than 380nm, and the term "visible light" refers to an active energy ray having a wavelength of 380nm or more and 800nm or less.

[ A1 ] A radically polymerizable resin composition

The radical polymerizable resin composition contains a radical polymerizable compound as a curable component. Examples of the radical polymerizable compound include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group or a vinyl group. The radical polymerizable compound may be either a monofunctional radical polymerizable compound or a bifunctional or more polyfunctional radical polymerizable compound. The radical polymerizable compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds. The radical polymerizable compound is suitably a compound having a (meth) acryloyl group, for example.

(monofunctional radical polymerizable Compound)

Examples of the monofunctional radical polymerizable compound include a (meth) acrylamide derivative having a (meth) acrylamide group. The (meth) acrylamide derivative is preferable in that it not only ensures adhesion between the brightness enhancement film and the cured product layer, but also has a high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include (meth) acrylamide derivatives having an N-alkyl group such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; (meth) acrylamide derivatives having an N-hydroxyalkyl group such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propane (meth) acrylamide; (meth) acrylamide derivatives having an N-aminoalkyl group such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; (meth) acrylamide derivatives having an N-alkoxy group such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; and (meth) acrylamide derivatives having an N-mercaptoalkyl group such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide. Examples of the heterocyclic ring-containing (meth) acrylamide derivative in which the nitrogen atom of the (meth) acrylamide group forms a heterocyclic ring include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, and the like.

Among the (meth) acrylamide derivatives, when the cured product layer is provided in direct contact with the brightness enhancing film, the (meth) acrylamide derivative containing an N-hydroxyalkyl group is preferable from the viewpoint of adhesion, and N-hydroxyethyl (meth) acrylamide is particularly preferable.

Examples of the monofunctional radical polymerizable compound include various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, (meth) acrylic acid (1 to 20 carbon atoms) alkyl esters such as t-amyl (meth) acrylate, 3-amyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, hexadecyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and n-octadecyl (meth) acrylate.

Examples of the (meth) acrylic acid derivative include cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; polycyclic (meth) acrylates such as 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; alkoxy-or phenoxy-containing (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and alkylphenoxypolyethylene glycol (meth) acrylate.

Examples of the (meth) acrylic acid derivative include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate; hydroxyl group-containing (meth) acrylates such as [4- (hydroxymethyl) cyclohexyl ] methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether; halogen-containing (meth) acrylates such as 2, 2, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, and 3-chloro-2-hydroxypropyl (meth) acrylate; alkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate; oxetanyl group-containing (meth) acrylates such as 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, 3-butyl-oxetanylmethyl (meth) acrylate, and 3-hexyl-oxetanylmethyl (meth) acrylate; (meth) acrylates having a heterocyclic ring such as tetrahydrofurfuryl (meth) acrylate and butyrolactone (meth) acrylate; hydroxypivalic acid neopentyl glycol (meth) acrylic acid adduct; p-phenylphenol (meth) acrylate, and the like.

Examples of the monofunctional radical polymerizable compound include carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the monofunctional radical polymerizable compound include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinylpyrrolidone; vinyl monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

As the monofunctional radical polymerizable compound, for example, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth) acrylic group at a terminal or in a molecule and having an active methylene group. Examples of the active methylene group include an acetoacetyl group, an alkoxymalonyl group, and a cyanoacetyl group, and the active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include acetoacetoxyalkyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxypropyl (meth) acrylate, and 2-acetoacetoxy-1-methylethyl (meth) acrylate; 2-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetyloxybutyl) acrylamide, N- (4-acetoacetyloxymethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth) acrylate.

(polyfunctional radical polymerizable Compound)

Examples of the polyfunctional radical polymerizable compound having two or more functional groups include N, N' -methylenebis (meth) acrylamide, tripropylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, 1, 10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, bisphenol a ethylene oxide adduct di (meth) acrylate, bisphenol a propylene oxide adduct di (meth) acrylate, bisphenol a diglycidyl ether di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyfunctional (meth) acrylamide derivatives, Esters of (meth) acrylic acid and a polyol such as tricyclodecane dimethanol di (meth) acrylate, cyclic trimethylolpropane formal (meth) acrylate, dioxane diol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and EO-modified diglycerol tetra (meth) acrylate; 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene, and the like. As specific examples, ARONIX M-220 (manufactured by Toyo Synthesis Co., Ltd.), LIGHT ACRYLATE 1, 9ND-A (manufactured by Kyoho chemical Co., Ltd.), LIGHT ACRYLATE DGE-4A (manufactured by Kyoho chemical Co., Ltd.), LIGHT ACRYLATE DCP-A (manufactured by Kyoho chemical Co., Ltd.), SR-531 (manufactured by Sartomer Co., Ltd.), CD-536 (manufactured by Sartomer Co., Ltd.) and the like are preferable. When these polyfunctional (meth) acrylamide derivatives are used, the radical polymerizable resin composition may contain various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate monomers, and the like, as required. It is preferable to add a polyfunctional (meth) acrylamide derivative to the radical polymerizable resin composition, because the polymerization rate is high, the productivity is excellent, and the crosslinking property when the resin composition is formed into a cured product is excellent.

From the viewpoint of controlling the water absorption of the cured product of the resin composition, the radical polymerizable compound preferably contains a polyfunctional radical polymerizable compound. Among the polyfunctional radical polymerizable compounds, those having a high logPow value described later are preferable.

The resin composition containing a curable compound for constituting the buffer layer is preferably a compound having a high octanol/water partition coefficient (hereinafter, sometimes referred to as "logPow value"). The logPow value is an index indicating lipophilicity of a substance, and is a logarithmic value of octanol/water partition coefficient. A high logPow means lipophilic, i.e. low water absorption. The logPow value (rocking flask method described in JIS-Z-7260) may be measured, but it may be calculated by calculation. In this specification, the logPow value calculated by ChemDraw Ultra manufactured by Cambridge Soft corporation is used. The logPow value of the resin composition can be calculated by the following formula.

logPow ═ Σ (logPowi × Wi) of the resin composition

logPowi: logPow value of each component contained in the resin composition

And Wi: (the number of moles of component i)/(the total number of moles of the resin composition)

The logPow value of the resin composition is preferably 1 or more, more preferably 2 or more, and most preferably 3 or more.

Examples of the radical polymerizable compound having a high logPow value include alicyclic (meth) acrylates such as tricyclodecane dimethanol di (meth) acrylate (logPow ═ 3.05) and isobornyl (meth) acrylate (logPow ═ 3.27); long-chain aliphatic (meth) acrylates such as 1, 9-nonanediol di (meth) acrylate (logPow ═ 3.68), 1, 10-decanediol diacrylate (logPow ═ 4.10); multi-branched (meth) acrylates such as hydroxypivalyl hydroxypivalate (meth) acrylic acid adduct (logPow ═ 3.35) and 2-ethyl-2-butylpropanediol di (meth) acrylate (logPow ═ 3.92); and aromatic ring-containing (meth) acrylates such as bisphenol a di (meth) acrylate (logPow ═ 5.46), bisphenol a ethylene oxide 4 mol adduct di (meth) acrylate (logPow ═ 5.15), bisphenol a propylene oxide 2 mol adduct di (meth) acrylate (logPow ═ 6.10), bisphenol a propylene oxide 4 mol adduct di (meth) acrylate (logPow ═ 6.43), 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl ] fluorene (logPow ═ 7.48), and p-phenylphenol (meth) acrylate (logPow ═ 3.98).

The radical polymerizable compound is preferably used in combination with a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound from the viewpoint of achieving both the adhesiveness between the brightness enhancing film and the cured product layer and the optical durability under severe environments. In general, it is preferable to use a monofunctional radical polymerizable compound in a ratio of 3 to 80 wt% and a polyfunctional radical polymerizable compound in a ratio of 20 to 97 wt% based on 100 wt% of the radical polymerizable compound.

(photopolymerization initiator)

When the radical polymerizable resin composition contains an active energy ray-curable component as a curable component, the radical polymerizable resin composition can be used in the form of a composition containing an active energy ray-curable compound. In this case, the radical polymerizable resin composition preferably contains a photopolymerization initiator.

As the photopolymerization initiator contained in the radical polymerizable resin composition, a photopolymerization initiator that is cleaved by ultraviolet rays or visible light can be used. Examples of such photopolymerization initiators include benzophenone-based compounds such as benzil, benzophenone, benzoylbenzoic acid, and 3, 3' -dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone and 2-methyl-1- [4- (methylthio) -phenyl ] -2-morpholinopropan-1-one; benzoin ether-based compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active oxime compounds such as 1-phenyl-1, 1-propanedione-2- (o-ethoxycarbonyl) oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone and dodecylthioxanthone; camphorquinone; a halogenated ketone; an acylphosphine oxide; acyl phosphonates and the like. Among the photopolymerization initiators, those having a high logPow value are preferable. The logPow value of the photopolymerization initiator is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more.

The content of the photopolymerization initiator in the radical-polymerizable resin composition is 20 parts by weight or less based on 100 parts by weight of the total amount of the curable components (radical-polymerizable compound). The amount of the photopolymerization initiator is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight, and still more preferably 0.1 to 5 parts by weight.

When the radical polymerizable resin composition contains a visible light curable compound, a photopolymerization initiator highly sensitive to light of 380nm or more is particularly preferably used.

Examples of the photopolymerization initiator include a compound represented by the following general formula (4) (hereinafter, may be referred to as "compound (4)").

[ solution 3]

[ in the formula, R ¹¹ And R ¹² Each independently is-H, -CH ₂ CH ₃ -iPr (isopropyl) or-Cl, R ¹¹ And R ¹² May be the same as or different from each other.]

In the radical polymerizable resin composition, the compound (4) may be used alone, or may be used in combination with a photopolymerization initiator having high sensitivity to light of 380nm or more, which will be described later. By using the compound (4), the adhesion between the luminance enhancement film and the cured product layer can be improved as compared with the case where a photopolymerization initiator highly sensitive to light of 380nm or more is used alone. Among the compounds (4), R is also particularly preferred ¹¹ And R ¹² is-CH ₂ CH ₃ Diethyl thioxanthone (ll). The content of the compound (4) in the radical polymerizable resin composition is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and still more preferably 0.9 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components (radical polymerizable compounds).

Examples of the photopolymerization initiator having high sensitivity to light having a wavelength of 380nm or more include 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone, 2, 4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2, 4, 6-trimethylbenzoyl) -phenylphosphine oxide, bis (. eta.5-2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium and the like.

The radical-polymerizable resin composition preferably contains a compound represented by the following general formula (5) (hereinafter, sometimes referred to as "compound (5)") in addition to the compound (4).

[ solution 4]

[ in the formula, R ¹³ 、R ¹⁴ And R ¹⁵ Each independently is-H, -CH ₃ 、-CH ₂ CH ₃ -iPr or-Cl, R ¹³ 、R ¹⁴ And R ¹⁵ May be the same as or different from each other.]

As the compound (5), for example, commercially available 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE907, manufactured by BASF) can be suitably used. In addition, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone (trade name: IRGACURE369, manufactured by BASF) and 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholinophenyl ] -1-butanone (trade name: IRGACURE379, manufactured by BASF) are also preferable because of their high sensitivity.

The radical polymerizable resin composition may contain a polymerization initiation aid as needed. Examples of the polymerization initiation aid include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., and ethyl 4-dimethylaminobenzoate is particularly preferable. When a polymerization initiator is used, the content of the polymerization initiator in the radical polymerizable resin composition is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components (radical polymerizable compounds).

(radical polymerizable Compound (a1) having active methylene group and radical polymerization initiator (a2) having dehydrogenation function.)

When the radical polymerizable compound (a1) having an active methylene group is used as the radical polymerizable compound contained in the radical polymerizable resin composition, it is preferably used in combination with the radical polymerization initiator (a2) having a dehydrogenation function. According to such a radical-polymerizable resin composition, even in an environment of particularly high humidity, when a cured layer is provided in direct contact with a brightness enhancement film, good adhesion can be ensured. Although the reason is not clear, it can be estimated as follows. The radical polymerizable compound (a1) having an active methylene group is polymerized together with other radical polymerizable compounds constituting the cured product layer, and is introduced into the main chain and/or side chain of the matrix polymer in the cured product layer to form the cured product layer. In this polymerization process, if the radical polymerization initiator (a2) having a dehydrogenation function is present, hydrogen is removed from the radical polymerizable compound (a2) having an active methylene group while forming a matrix polymer constituting the cured product layer, and radicals are generated in the methylene group. Thereafter, the methylene groups that generate free radicals react with the hydroxyl groups of the brightness enhancing film to form covalent bonds between the cured layer and the brightness enhancing film. As a result, the adhesion between the brightness enhancement film and the cured product layer is improved even in a particularly high humidity environment.

Examples of the radical polymerization initiator (a2) having a dehydrogenation function include a thioxanthone-based radical polymerization initiator and a benzophenone-based radical polymerization initiator. The radical polymerization initiator (a2) is preferably a thioxanthone-based radical polymerization initiator. Examples of the thioxanthone-based radical polymerization initiator include the compound (4) described above. Specific examples of the compound (4) include thioxanthone, dimethylthioxanthone, diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, and the like. Among the compounds (4), R is particularly preferred ¹¹ And R ¹² is-CH ₂ CH ₃ Diethyl thioxanthone (ll).

When the radical polymerizable compound (a1) having an active methylene group and the radical polymerization initiator (a2) having a dehydrogenation function are contained in the radical polymerizable resin composition, it is preferable that the radical polymerizable compound (a1) having an active methylene group is contained in an amount of 1 to 50% by weight and the radical polymerization initiator (a2) is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total amount of the curable components, assuming that the total amount of the curable components (radical polymerizable compounds) is 100% by weight.

As described above, it is considered that the methylene group of the radical polymerizable compound (a1) having an active methylene group generates a radical in the presence of the radical polymerization initiator (a2) having a dehydrogenation function, and the methylene group reacts with the hydroxyl group of the brightness enhancing film to form a covalent bond. Therefore, in order to generate radicals from the methylene groups of the radically polymerizable compound (a1) having an active methylene group and to form the covalent bonds sufficiently, the radically polymerizable compound (a1) having an active methylene group is preferably contained in an amount of 1 to 50 wt%, more preferably 3 to 30 wt%, based on 100 wt% of the total amount of the curable components (radically polymerizable compounds). In order to sufficiently improve the water resistance and improve the adhesion between the luminance enhancement film and the cured product layer in a high humidity environment, the radical polymerizable compound (a1) having an active methylene group is preferably 1% by weight or more. On the other hand, if the amount is more than 50% by weight, poor curing of the cured product layer may occur. The radical polymerization initiator (a2) having a dehydrogenation function is preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 0.3 to 9 parts by weight, based on 100 parts by weight of the total amount of the curable components. In order to sufficiently promote the dehydrogenation reaction, it is preferable to use 0.1 part by weight or more of the radical polymerization initiator (a 2). On the other hand, if the amount is more than 10 parts by weight, the radical polymerizable resin composition may not be completely dissolved.

[ A2 ] cationic polymerization type resin composition

The cationically polymerizable resin composition contains a cationically polymerizable compound as a curable component. The cationically polymerizable compound is classified into a monofunctional cationically polymerizable compound having 1 cationically polymerizable functional group in a molecule and a polyfunctional cationically polymerizable compound having 2 or more cationically polymerizable functional groups in a molecule. Since the monofunctional cationic polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by adding the compound to the cationic polymerization type resin composition. Further, since the monofunctional cationically polymerizable compound often has a functional group that can exhibit various functions, the resin composition and/or the layer of a cured product of the resin composition can exhibit various functions by including the cationically polymerizable resin composition.

Since the cured product layer can be three-dimensionally crosslinked, it is preferable to contain a polyfunctional cationic polymerizable compound in the resin composition. The compounding ratio of the monofunctional cationic polymerizable compound and the polyfunctional cationic polymerizable compound in the cationic polymerizable resin composition is preferably in the range of 10 parts by weight or more and 1000 parts by weight or less relative to 100 parts by weight of the monofunctional cationic polymerizable compound.

Examples of the cationically polymerizable functional group include an epoxy group, an oxetanyl group, and a vinyl ether group. Examples of the compound having an epoxy group include an aliphatic epoxy compound, an alicyclic epoxy compound, and an aromatic epoxy compound, and the cationic polymerization resin composition preferably contains an alicyclic epoxy compound in particular because of excellent curability and adhesiveness.

Examples of the alicyclic epoxy compound include 3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate, a caprolactone-modified product, a trimethylcaprolactone-modified product, and a valerolactone-modified product of 3, 4-epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate, and specifically include Celloxide 2021, Celloxide 2021A, Celloxide 2021P, Celloxide 2081, Celloxide 2083, and Celloxide 2085 (the above is manufactured by DAICEL CHEMICAL Co., Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, and R-6110 (the above is manufactured by DOW CHEMICAL Japan Co., Ltd.).

The cationic polymerization resin composition preferably contains a compound having an oxetanyl group because of its effect of improving curability and reducing liquid viscosity of the composition. Examples of the oxetanyl group-containing compound include 3-ethyl-3-hydroxymethyloxetane, 1, 4-bis [ (3-ethyl-3-oxetanyl) methoxymethyl ] benzene, 3-ethyl-3- (phenoxymethyl) Oxetane, bis [ (3-ethyl-3-oxetanyl) methyl ] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) Oxetane, phenol linear phenolaldehyde Oxetane and the like, and Aron Oxetane OXT-101, Aron Oxetane OXT-121, Aron Oxetane OXT-211, Aron Oxetane OXT-221 and Aron Oxetane OXT-212 (manufactured by Toyo Seisaku-Sho Co., Ltd.) are commercially available.

The compound having a vinyl ether group is preferably contained because of the effect of improving curability of the cationic polymerization resin composition and reducing liquid viscosity of the composition. Examples of the compound having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetravinyl ether, and the like.

(photo cation polymerization initiator)

The cationic polymerization type resin composition contains at least 1 compound selected from the group consisting of a compound having an epoxy group, a compound having an oxetanyl group and a compound having a vinyl ether group as the curable component. Since these compounds are all compounds that are cured by cationic polymerization, the cationic polymerization type resin composition preferably further contains a photo cationic polymerization initiator. The photo cation polymerization initiator generates a cation species or lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., and initiates a polymerization reaction of an epoxy group or an oxetanyl group. As the photo cation polymerization initiator, a photo acid generator described later can be suitably used.

When the resin composition containing the curable compound contains a visible light-curable compound, it is preferable to use a photo cation polymerization initiator which is highly sensitive to light of 380nm or more in particular, and since the photo cation polymerization initiator is usually a compound which exhibits a maximum absorption in the vicinity of 300nm or a shorter wavelength region than this, by blending a photosensitizer which exhibits a maximum absorption in a longer wavelength region than this, specifically, in a wavelength region of more than 380nm, it is possible to induce light of a wavelength in the vicinity and to promote the generation of cationic species or acid from the photo cation polymerization initiator. Examples of the photosensitizing agent include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducing dyes, and the like, and 2 or more of them may be used in combination. Particularly, anthracene compounds are preferable because of their excellent photosensitizing effect, and specific examples thereof include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki chemical Co., Ltd.). The content of the photosensitizing agent is preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight.

[ A3 ] other Components

The resin composition containing an active energy ray-curable compound may contain a (meth) acrylic oligomer, a photoacid generator, an epoxy group-or alkoxy group-containing compound, a silane coupling agent, a compound having a vinyl ether group, and additives other than these. These components are explained below.

((meth) acrylic acid-based oligomer)

The radical polymerizable resin composition or the cation polymerizable resin composition may contain a (meth) acrylic oligomer obtained by polymerizing a (meth) acrylic monomer in addition to a radical polymerizable compound or a cation polymerizable compound (curable component). By including the (meth) acrylic oligomer in the resin composition, curing shrinkage when the resin composition is cured by irradiation with an active energy ray can be reduced, and the interface stress between the cured product layer and the brightness enhancement film can be reduced. As a result, the deterioration of the adhesion between the cured product layer of the resin composition and the brightness enhancement film can be suppressed. In order to sufficiently suppress the curing shrinkage of the cured product layer, the (meth) acrylic oligomer is preferably contained in an amount of 3 parts by weight or more, more preferably 5 parts by weight or more, based on 100 parts by weight of the total amount of the curable components. If the content of the (meth) acrylic oligomer in the resin composition is too large, the reaction rate when the resin composition is irradiated with active energy rays may be drastically reduced, which may result in poor curing. In order to sufficiently suppress the decrease in the reaction rate, the (meth) acrylic oligomer is preferably contained in an amount of 20 parts by weight or less, more preferably 15 parts by weight or less, based on 100 parts by weight of the total amount of the curable components.

In view of workability and uniformity in coating, the radical polymerization type resin composition or the cation polymerization type resin composition is preferably low in viscosity, and therefore the (meth) acrylic oligomer is also preferably low in viscosity. The (meth) acrylic oligomer having a low viscosity and capable of preventing curing shrinkage of the cured product layer is preferably an oligomer having a weight average molecular weight (Mw) of 15000 or less, more preferably an oligomer having a weight average molecular weight (Mw) of 10000 or less, and particularly preferably an oligomer having a weight average molecular weight of 5000 or less.

On the other hand, in order to sufficiently suppress cure shrinkage of the cured product layer, the weight average molecular weight (Mw) of the (meth) acrylic oligomer is preferably 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more.

Examples of the (meth) acrylic monomer constituting the (meth) acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, hexadecyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and the like, Alkyl esters (having 1 to 20 carbon atoms) of (meth) acrylic acid such as N-octadecyl (meth) acrylate; cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.); aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, etc.); polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, etc.); hydroxyl group-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropylmethyl-butyl (meth) methacrylate, etc.); (meth) acrylates having an alkoxy group or a phenoxy group (e.g., 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.); epoxy group-containing (meth) acrylates (e.g., glycidyl (meth) acrylate); halogen-containing (meth) acrylates (e.g., 2, 2, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.); alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate) and the like. These (meth) acrylates may be used alone or in combination of 2 or more.

Specific examples of the (meth) acrylic oligomer include "ARUFON" manufactured by east asia synthesis corporation, "ACTFLOW" manufactured by integrated research chemical corporation, and "JONCRYL" manufactured by BASF Japan corporation. Among the (meth) acrylic oligomers, those having a high logPow value are preferable. The logPow value of the (meth) acrylic oligomer is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more.

(photoacid generators)

The resin composition containing an active energy ray-curable compound may contain a photoacid generator. When the photoacid generator is contained in the resin composition, the water resistance and durability of the cured product layer can be greatly improved as compared with the case where the photoacid generator is not contained. The photoacid generator can be represented by the following general formula (6).

[ solution 5]

L ⁺ X ^- …(6)

[ in the formula, L ⁺ Represents an optional onium cation. In addition, X ^- Is selected from PF ₆ ^- 、SbF ₆ ^- 、AsF ₆ ^- 、SbCl ₆ ^- 、BiCl ₅ ^- 、SnCl ₆ ^- 、ClO ₄ ^- Dithiocarbamate anions, SCN ^- The counter anion of (1).]

X ^- Preferably PF ₆ ^- 、SbF ₆ ^- Or AsF ₆ ^- More preferably PF ₆ ^- Or SbF ₆ ^- 。

Examples of the preferable onium salt constituting the photoacid generator include "Cyracure UVI-6992", "Cyracure UVI-6974" (manufactured by DOW CHEMICAL Japan K.K.; "Adeka Optomer SP 150", "Adeka Optomer SP 152", "Adeka Optomer SP 170", "Adeka Optomer SP 172" (manufactured by ADEKA Co., Ltd.; "IRGACURE 250" (manufactured by Ciba specialty Chemicals Co., Ltd.), "CI-2", "CI-2855" (manufactured by Nippon Cao Co., Ltd.), "SAN-Aid SI-60L", "SAN-Aid SI-80L", "SAN-Aid SI-100L", "SAN-Aid SI-110L", "SAN-Aid SI-180L" (manufactured by Sanxin CHEMICAL Co., Ltd.), "CPI-100P", "SAN-100A" (manufactured by SAN-RO APK.K.; manufactured by, "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044", "WPI-054", "WPI-055", "WPAG-281", "WPAG-567" and "WPAG-596" (manufactured by Wako pure chemical industries, Ltd.).

The photoacid generator is 10 parts by weight or less, preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and particularly preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components contained in the resin composition containing the active energy ray-curable compound.

(Compound containing epoxy group or alkoxy group)

The resin composition containing an active energy ray-curable compound may further contain a compound containing an epoxy group or an alkoxy group together with the photoacid generator.

Examples of the compound containing an epoxy group include a compound having 1 or more epoxy groups in a molecule, a compound having 2 or more epoxy groups in a molecule, and a polymer compound (epoxy resin). When these compounds are used, compounds having two or more functional groups reactive with an epoxy group in a molecule may be used in combination. Examples of the functional group having reactivity with an epoxy group include a carboxyl group, a phenolic hydroxyl group, a mercapto group, a primary or secondary aromatic amino group, and the like. In view of three-dimensional curability, it is particularly preferable to have 2 or more of these functional groups in one molecule.

Examples of the compound having 1 or more epoxy groups in the molecule include epoxy resins, and polyfunctional epoxy resins such as bisphenol a type epoxy resins derived from bisphenol a and epichlorohydrin, bisphenol F type epoxy resins derived from bisphenol F and epichlorohydrin, bisphenol S type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol a novolac type epoxy resins, bisphenol F novolac type epoxy resins, alicyclic epoxy resins, diphenyl ether type epoxy resins, hydroquinone type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, fluorene type epoxy resins, 3-functional epoxy resins, and 4-functional epoxy resins; glycidyl ester type epoxy resins; glycidyl amine type epoxy resins; hydantoin type epoxy resins; isocyanurate type epoxy resins; aliphatic chain epoxy resins, and the like, and these epoxy resins may be halogenated or hydrogenated.

Examples of commercially available Epoxy Resin products include, but are not particularly limited to, JER COAT (Japanese: JER コ - ト)828, 1001, 801N, 806, 807, 152, 604, 630, 871, YX8000, YX8034, YX4000, EPICLON 830, EXA835LV, HP4032D, HP820, EP4100 series, EP4000 series, EPU series, Celloxide series (2021, 2021P, 2083, 2085, 3000, etc.) manufactured by DAICEL chemical Co., Ltd, EPE series, YDF series, YDCN series, YDB series, phenoxy resins (polyhydroxy polyethers synthesized from bisphenol and epichlorohydrin and having Epoxy groups at both ends; YP series, etc.), Chemgase series, Nagaese series, and Nagnex series. These epoxy resins may be used in combination of 2 or more.

The compound having an alkoxy group in the molecule is not particularly limited as long as it has 1 or more alkoxy groups in the molecule, and known compounds can be used. Examples of such a compound include melamine compounds, amino resins, and silane coupling agents.

The compound containing an epoxy group or an alkoxy group is contained in an amount of usually 30 parts by weight or less, preferably 20 parts by weight or less, based on 100 parts by weight of the total amount of the curable components contained in the resin composition containing an active energy ray-curable compound. If the content of the compound containing an epoxy group or an alkoxy group is too large, the adhesion of the cured product layer to the brightness enhancement film may be reduced, and the impact resistance in the drop test may be deteriorated. From the viewpoint of water resistance, the compound containing an epoxy group or an alkoxy group is preferably contained in an amount of 2 parts by weight or more, more preferably 5 parts by weight or more, based on 100 parts by weight of the total amount of the curable components contained in the resin composition.

(silane coupling agent)

The resin composition containing an active energy ray-curable compound may contain a silane coupling agent. In this case, the silane coupling agent is preferably an active energy ray-curable compound, but can impart water resistance to the cured product layer even if the silane coupling agent is not an active energy ray-curable compound.

Examples of the active energy ray-curable silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and 3-acryloxypropyltrimethoxysilane. Among them, 3-methacryloxypropyltrimethoxysilane and 3-acryloxypropyltrimethoxysilane are preferable.

The silane coupling agent that is not curable with active energy rays is preferably a silane coupling agent having an amino group. Examples of the silane coupling agent having an amino group include γ -aminopropyltrimethoxysilane, γ -aminopropyltriethoxysilane, γ -aminopropyltriisopropoxysilane, γ -aminopropylmethyldimethoxysilane, γ -aminopropylmethyldiethoxysilane, γ - (2-aminoethyl) aminopropyltrimethoxysilane, γ - (2-aminoethyl) aminopropylmethyldimethoxysilane, γ - (2-aminoethyl) aminopropyltriethoxysilane, γ - (2-aminoethyl) aminopropylmethyldiethoxysilane, γ - (2-aminoethyl) aminopropyltriisopropoxysilane, γ - (2- (2-aminoethyl) aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-triethoxysilane, gamma-aminopropyltriethoxysilane, gamma-N-terminal-amino groups, gamma-aminopropyltriethoxysilane, gamma-trimethoxysilane, gamma-2-aminoethyl-aminoethoxysilane, gamma-isopropyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-methyldiethoxysilane, gamma-bis (2-amino-2-amino-methyl-2-ethyl) silane, Gamma- (6-aminohexyl) aminopropyltrimethoxysilane, 3- (N-ethylamino) -2-methylpropyltrimethoxysilane, gamma-ureidopropyltrimethoxysilane, gamma-ureidopropyltriethoxysilane, N-phenyl-gamma-aminopropyltrimethoxysilane, N-benzyl-gamma-aminopropyltrimethoxysilane, amino group-containing silanes such as N-vinylbenzyl-gamma-aminopropyltriethoxysilane, N-cyclohexylaminomethyltriethoxysilane, N-cyclohexylaminomethyldiethoxymethylsilane, N-phenylaminomethyltrimethoxysilane, (2-aminoethyl) aminomethyltrimethoxysilane, and N, N' -bis [3- (trimethoxysilyl) propyl ] ethylenediamine; ketimine-type silanes such as N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propylamine.

Examples of the silane coupling agent other than those described above which are not curable by active energy rays include 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazolesilane.

Among them, in order to ensure good adhesion, gamma-aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, gamma- (2-aminoethyl) aminopropylmethyldiethoxysilane, N- (1, 3-dimethylbutylidene) -3- (triethoxysilyl-1-propylamine are preferable, and only 1 kind of the silane coupling agent having an amino group may be used, or 2 or more kinds may be used in combination.

The silane coupling agent is preferably contained in an amount of 0.01 to 20 parts by weight, more preferably 0.05 to 15 parts by weight, and still more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the total amount of curable components contained in the resin composition containing the active energy ray-curable compound. If the content of the silane coupling agent is too large, the storage stability of the resin composition is deteriorated, and if the content of the silane coupling agent is too small, the effect of adhesion water resistance is hardly exhibited.

(Compound having vinyl Ether group)

The resin composition containing an active energy ray-curable compound may contain a compound having a vinyl ether group. By containing a compound having a vinyl ether group, the adhesion water resistance between the luminance enhancement film and the cured product layer can be improved. This is presumably because the vinyl ether group interacts with the brightness enhancement film to improve the adhesion. In order to further improve the water resistance of the adhesion between the brightness enhancing film and the cured product layer, a radical polymerizable compound is preferably used as the compound having a vinyl ether group. The compound having a vinyl ether group is preferably contained in an amount of 0.1 to 19 parts by weight based on 100 parts by weight of the total amount of the curable components contained in the resin composition containing the active energy ray-curable compound.

(additives)

The resin composition containing an active energy ray-curable compound may contain various additives in addition to the above-described (meth) acrylic oligomer, photoacid generator, compound containing an epoxy group or alkoxy group, silane coupling agent, and compound having a vinyl ether group, within a range not impairing the object and effect of the present invention. Examples of the additive include polymers or oligomers such as epoxy resins, polyamides, polyamideimides, polyurethanes, polybutadienes, polychloroprenes, polyethers, polyesters, styrene-butadiene block copolymers, petroleum resins, xylene resins, ketone resins, cellulose resins, fluorine-based oligomers, silicone-based oligomers, and polysulfide-based oligomers; polymerization inhibitors such as phenothiazine and 2, 6-di-tert-butyl-4-methylphenol; a polymerization initiation aid; leveling agent; a wettability modifier; a surfactant; a plasticizer; an ultraviolet absorber; an inorganic filler; a pigment; dyes, and the like. Among the above additives, those having a high logPow value are preferable. The logPow value of the additive is preferably 2 or more, more preferably 3 or more, and most preferably 4 or more. The additive is usually contained in an amount of 0 to 10 parts by weight, preferably 0 to 5 parts by weight, and more preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components contained in the resin composition containing the active energy ray-curable compound.

[ B ] thermosetting compound

As the thermosetting compound, a thermosetting adhesive, a hot melt adhesive, or the like can be used from the viewpoint of adhesiveness between the brightness enhancing film and the cured product layer. Specific examples thereof include natural rubber adhesives, α -olefin adhesives, urethane resin adhesives, ethylene-vinyl acetate resin emulsion adhesives, ethylene-vinyl acetate resin hot-melt adhesives, epoxy resin adhesives, vinyl chloride resin solvent adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, silicone adhesives, styrene-butadiene rubber solvent adhesives, nitrile rubber adhesives, nitrocellulose adhesives, reactive hot-melt adhesives, phenol resin adhesives, modified silicone adhesives, polyester hot-melt adhesives, polyamide resin hot-melt adhesives, polyimide adhesives, polyurethane resin hot-melt adhesives, polyolefin resin hot-melt adhesives, polyvinyl acetate resin solvent adhesives, polyurethane resin adhesives, polyester resins, polyurethane resins, and the like, A polystyrene resin solvent adhesive, a polyvinyl alcohol adhesive, a polyvinyl pyrrolidone resin adhesive, a polyvinyl butyral adhesive, a polybenzimidazole adhesive, a polymethacrylate resin solvent adhesive, a melamine resin adhesive, a urea resin adhesive, a resorcinol adhesive, and the like. Such adhesives may be used alone in 1 kind or in combination of 2 or more kinds, and base polymers corresponding to the kinds of adhesives may be used.

The thermosetting adhesive exhibits adhesive strength by being cured (japanese: cured) after being thermally cured by heating. Examples of the thermosetting adhesive include epoxy thermosetting adhesives, urethane thermosetting adhesives, and acrylic thermosetting adhesives. The curing temperature of the thermosetting adhesive is, for example, 100 to 200 ℃.

The hot melt adhesive is melted or softened by heating, thermally welded to the brightness enhancement film, and then solidified by cooling, thereby adhering to the brightness enhancement film. Examples of the hot-melt adhesive include a rubber hot-melt adhesive, a polyester hot-melt adhesive, a polyolefin hot-melt adhesive, an ethylene-vinyl acetate resin hot-melt adhesive, a polyamide resin hot-melt adhesive, and a polyurethane resin hot-melt adhesive. The softening temperature (ring and ball method) of the hot melt adhesive is, for example, 100 to 200 ℃. The melt viscosity of the hot-melt adhesive is, for example, 100 to 30000 mPas at 180 ℃.

[ linearly polarizing layer ]

The linear polarization layer has a property of transmitting a linear polarization having a vibration plane perpendicular to the absorption axis when unpolarized light is incident. The linear polarizing layer is preferably a layer containing a polyvinyl alcohol (hereinafter, also referred to simply as "PVA") resin film.

Examples of the linearly polarizing layer including a PVA-based resin film include a film obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol (hereinafter, may be abbreviated as "PVA") based film, a partially formalized PVA based film, and an ethylene-vinyl acetate copolymer partially saponified film to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, and a stretching treatment. From the viewpoint of excellent optical properties, it is preferable to use a linear polarizing layer obtained by dyeing a PVA-based resin film with iodine and uniaxially stretching the PVA-based resin film.

The polyvinyl alcohol resin can be produced by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be polyvinyl acetate which is a homopolymer of vinyl acetate, or may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, or the like modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol resin is usually about 1000 to 10000, preferably about 1500 to 5000.

A film obtained by forming such a polyvinyl alcohol resin film is used as a material film of a linearly polarizing layer. The method for forming the film of the polyvinyl alcohol resin is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol resin material film is, for example, about 10 to 100 μm, preferably about 10 to 60 μm, and more preferably about 15 to 30 μm.

As another method for producing a linearly polarizing layer including a PVA-based resin film, there is a method including the steps of preparing a base film, coating a solution of a resin such as a polyvinyl alcohol-based resin on the base film, and drying the coating to remove the solvent to form a resin layer on the base film. A primer layer may be formed in advance on the surface of the substrate film on which the resin layer is formed. As the base film, a resin film such as PET can be used. Examples of the material of the primer layer include a resin obtained by crosslinking a hydrophilic resin used for the linear polarizing layer.

Then, if necessary, the amount of solvent such as water in the resin layer is adjusted, and then the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with a dichroic dye such as iodine to adsorb the dichroic dye in the resin layer and orient the dichroic dye. Next, the resin layer having the dichroic dye adsorbed thereon and oriented is treated with an aqueous boric acid solution as necessary, and a washing step of washing off the aqueous boric acid solution is performed. In this way, a resin layer in which a dichroic dye is adsorbed and aligned, that is, a film of a linearly polarizing layer is produced. In each step, a known method can be used.

The uniaxial stretching of the base film and the resin layer may be performed before dyeing, during boric acid treatment after dyeing, or in a plurality of stages of these. The base film and the resin layer may be uniaxially stretched in the MD direction (film transport direction), and in this case, the base film and the resin layer may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a heat roll. The substrate film and the resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film transport direction), and in this case, a so-called tenter method may be used. The stretching of the base film and the resin layer may be dry stretching in which the stretching is performed in the atmosphere, or wet stretching in which the stretching is performed in a state where the resin layer is swollen with a solvent. In order to exhibit the performance of the linear polarizing layer, the stretching magnification is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. The upper limit of the stretch ratio is not particularly limited, but is preferably 8 times or less from the viewpoint of suppressing breakage or the like.

The linear polarizing layer produced by the above method can be obtained by laminating a protective layer described later and then peeling off the base film.

The thickness of the linear polarizing layer is preferably 5 μm or more, more preferably 10 μm or more, and may be 15 μm or more, and may be 20 μm or more. The thickness of the linear polarizing layer is 50 μm or less, preferably 40 μm or less, and may be 30 μm or less.

[ polarizing plate ]

The linear polarizing layer may be a polarizing plate obtained by laminating a1 st protective layer, or a1 st protective layer and a2 nd protective layer (hereinafter, the 1 st protective layer and the 2 nd protective layer may be collectively referred to as "protective layer") on one surface or both surfaces thereof via a known pressure-sensitive adhesive layer or adhesive layer. The polarizing plate is a so-called linear polarizing plate. As the protective layer that can be laminated on one surface or both surfaces of the linearly polarizing layer, for example, a film made of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, water resistance, isotropy, stretchability, and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resin; polysulfone resin; a polycarbonate resin; polyamide resins such as nylon and aromatic polyamide; a polyimide resin; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having a ring system and a norbornene structure (also referred to as norbornene-based resins); a (meth) acrylic resin; a polyarylate resin; a polystyrene resin; a polyvinyl alcohol resin; and mixtures thereof. When protective layers are laminated on both surfaces of the linearly polarizing layer, the resin compositions of the two protective layers may be the same or different.

In order to improve adhesion to the linearly polarizing layer, a film made of a thermoplastic resin may be subjected to a surface treatment (e.g., corona treatment), or a thin layer such as a primer layer (also referred to as an undercoat layer) may be formed.

The protective layer may be, for example, a layer obtained by stretching the above thermoplastic resin, or may be a layer which is not stretched (hereinafter, may be referred to as "unstretched resin"). Examples of the stretching treatment include uniaxial stretching and biaxial stretching.

Examples of the adhesive layer used for laminating the protective layer on the linearly polarizing layer include adhesives described in the 1 st adhesive layer and the like described later. As the adhesive layer used for laminating the protective layer on the linearly polarizing layer, a known adhesive can be used. The adhesive is an adhesive other than a pressure-sensitive adhesive (pressure-sensitive adhesive), and examples thereof include an aqueous adhesive and an active energy ray-curable adhesive. Examples of the water-based adhesive include adhesives obtained by dissolving or dispersing a polyvinyl alcohol resin in water. Examples of the active energy ray-curable adhesive include solvent-free active energy ray-curable adhesives containing a curable compound that is cured by irradiation with an active energy ray such as ultraviolet light, visible light, electron beam, or X-ray.

[ Brightness enhancement film ]

The brightness enhancement film uses a polarization conversion element having a function of separating light emitted from a light source such as a backlight into transmission polarized light and reflection polarized light or scattering polarized light. The brightness enhancement film can improve the emission efficiency of linearly polarized light by using the return light (Japanese: re- light) from the light source which reflects polarized light or scatters polarized light.

An anisotropic reflective polarizer can be used as a brightness enhancing film. Examples of the anisotropic reflective polarizing plate include a polarizing plate which exhibits a property of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer film of dielectric materials or a multilayer laminate of layers having different refractive index anisotropies, and a polarizing plate which exhibits a property of reflecting either left-handed or right-handed circularly polarized light and transmitting other light, such as an alignment film in which a cholesteric liquid crystal polymer is supported on a film substrate or a polarizing plate in which an alignment liquid crystal layer is provided. The number of layers constituting the anisotropic reflective polarizer may be 2 or more.

For example, a laminate obtained by alternately laminating a material that generates a retardation by stretching, such as polyethylene naphthalate, polyethylene terephthalate, or polycarbonate, and a resin that exhibits a small amount of retardation, such as an acrylic resin, such as polymethyl methacrylate, or a norbornene resin, such as "Arton" (registered trademark) manufactured by JSR corporation, and uniaxially stretching the resulting material can be used as the brightness enhancement film. Specific examples of such a structure include "DBEF" (registered trademark), "APF-V4" (product name), "APF-V3" (product name) and "APF-V2" (product name) manufactured by 3M company.

The brightness enhancement film may be, for example, a laminate of a cholesteric liquid crystal layer and a λ/4 plate. Specific examples of such a laminate include a product name "PCF" manufactured by ritonavir electric corporation.

The brightness enhancement film may also be a reflective grid polarizer. As the reflective grid polarizer, a metal lattice reflective polarizer in which metal is finely processed to emit a reflective polarized light in a visible light region can be given.

The thickness of the brightness enhancement film is usually not less than 5 μm, but may be not less than 10 μm, and is usually not more than 100 μm, preferably not more than 50 μm, and may be not more than 35 μm.

[ 1 st adhesive layer, 2 nd adhesive layer, 3 rd adhesive layer ]

The 1 st adhesive layer, the 2 nd adhesive layer, and the 3 rd adhesive layer (hereinafter, these may be collectively referred to as "adhesive layers") are layers formed of an adhesive. The "pressure-sensitive adhesive" used herein is a material exhibiting adhesiveness by adhering itself to an adherend such as a polarizing plate or a liquid crystal layer, and is called a so-called pressure-sensitive adhesive. The active energy ray-curable adhesive described later can be adjusted in the degree of crosslinking and the adhesive strength by irradiation with an energy ray.

As the binder, conventionally known binders having excellent optical transparency can be used without particular limitation, and for example, binders having a base polymer such as an acrylic, urethane, silicone, or polyvinyl ether can be used. Further, an active energy ray-curable adhesive, a thermosetting adhesive, or the like may be used. Among them, those having excellent transparency, adhesive force, removability (hereinafter also referred to as reworkability), weather resistance, heat resistance and the like and containing an acrylic resin as a base polymer are suitable. The pressure-sensitive adhesive layer is preferably composed of a reaction product of a pressure-sensitive adhesive composition containing a (meth) acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

The adhesive layer may be formed using an active energy ray-curable adhesive. In the active energy ray-curable adhesive, an ultraviolet-curable compound such as a polyfunctional acrylate is blended in the adhesive composition, and after the adhesive layer is formed, the adhesive layer is irradiated with ultraviolet rays and cured, whereby a harder adhesive layer can be formed. The active energy ray-curable adhesive has a property of being cured by irradiation with an energy ray such as ultraviolet ray or electron beam. The activated energy ray-curable pressure-sensitive adhesive has adhesiveness even before irradiation with an energy ray, and thus has properties of being capable of adhering to an adherend such as an optical film or a liquid crystal layer and being cured by irradiation with an energy ray to adjust the adhesion force.

The active energy ray-curable adhesive generally contains an acrylic adhesive and an energy ray-polymerizable compound as main components. Usually, a crosslinking agent is further blended, and a photopolymerization initiator, a photosensitizer and the like may be further blended as necessary.

The storage modulus of the adhesive layer is preferably 0.10 to 10.0MPa, more preferably 0.15 to 5.0MPa at 23 ℃. When the storage modulus at 23 ℃ is 0.10MPa or more, problems such as peeling can be suppressed when a temperature change occurs, and therefore, it is preferable. Further, it is preferably 10.0MPa or less because the durability is less likely to be reduced due to the reduction of the adhesive force. The storage modulus of the adhesive layer can be measured by the method described in examples.

The thickness of the pressure-sensitive adhesive layer is preferably 3 μm or more, more preferably 5 μm or more. The thickness of the pressure-sensitive adhesive layer is preferably 40 μm or less, and more preferably 30 μm or less.

[ Release film ]

The release film is a film for protecting the pressure-sensitive adhesive layer or supporting the pressure-sensitive adhesive layer, and has a function as a separator that can be released from the pressure-sensitive adhesive layer. Examples of the release film include a film obtained by subjecting the surface of the base film on the pressure-sensitive adhesive layer side to a release treatment such as a silicone treatment. Examples of the resin material for forming the base film include the same resin materials as those for forming the protective layer. The resin film may have a 1-layer structure or a multilayer structure having 2 or more layers.

Examples

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

[ measurement of thickness ]

The thickness of each layer was measured using MH-15M as a digital height gauge manufactured by Nikon corporation.

[ measurement of in-plane retardation ]

The in-plane retardation Re (590) of the buffer layer at a wavelength of 590nm was measured using AxoScan (Axometrics, inc.).

[ measurement of tensile elastic modulus ]

Rectangular measurement samples having an MD length of 100mm and a TD length of 20mm were cut out from the film used as the cushion layer. The MD length is a length of the linear polarizing layer of the composite polarizing plate in the direction corresponding to the absorption axis direction. The test specimen was pulled at a tensile rate of 1 mm/min in the MD longitudinal direction under an environment of 23 ℃ and 55% relative humidity by sandwiching both ends in the MD longitudinal direction of the test specimen with upper and lower clamps of a tensile tester [ Autograph AG-Xplus tester manufactured by shimadzu corporation ] at an interval of 5cm, and the tensile elastic modulus [ GPa ] in the MD longitudinal direction under the conditions of 23 ℃ and 55% relative humidity was calculated from the slope of the initial straight line of the obtained stress-strain curve.

[ high temperature durability test ]

From the composite polarizing plate obtained in example or comparative example, a sample having dimensions of MD length 160mm and TD length 100mm was obtained, and a release film was peeled off from the sample, and the exposed adhesive layer (3 rd adhesive layer) was bonded to a glass plate to prepare a test piece. The test piece was autoclaved at 50 ℃ and 0.5MPa for 15 minutes, and then put into an oven at 95 ℃ for 500 hours, and the appearance of the test piece on the side of the brightness enhancement film was visually observed.

[ example 1]

(preparation of Linear polarizing layer)

A polyvinyl alcohol film having a thickness of 75 μm and comprising polyvinyl alcohol having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more was uniaxially stretched in a dry manner by about 5 times, and was immersed in pure water at 60 ℃ for 1 minute while maintaining the stretched state, and then immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28 ℃ for 60 seconds. Thereafter, the plate was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72 ℃ for 300 seconds. Subsequently, the substrate was washed with pure water at 26 ℃ for 20 seconds and then dried at 65 ℃ to obtain a 28 μm-thick linear polarizing layer in which iodine was adsorbed to polyvinyl alcohol and oriented.

(preparation of adhesive)

50g of a modified PVA-based resin containing an acetoacetyl group (GOHSENX Z-410, manufactured by Mitsubishi chemical corporation) was dissolved in 950g of pure water, heated at 90 ℃ for 2 hours, and then cooled to room temperature to obtain a PVA solution. Then, the PVA solution, maleic acid, glyoxal, and pure water were mixed so that the respective compounds had the following concentrations to prepare a PVA-based adhesive.

PVA 3.0 wt.%

Maleic acid 0.01% by weight

Glyoxal 0.15% by weight

(preparation of polarizing plate)

The adhesive was applied to one surface of the linear polarizing layer obtained in the above-mentioned manner, a1 st protective layer (a 40 μm thick triacetyl cellulose film ("KC 4 UYW" product name of Konica Minolta Opto corporation)) was applied thereto, the adhesive was applied to the other surface thereof, a2 nd protective layer (a 40 μm thick acrylic resin film ("HX-40 NE" product name of toyoyo steel plate corporation)) was applied thereto, and the resultant was dried to prepare a polarizing plate. When these materials were bonded, the bonding surfaces of the respective materials were subjected to corona treatment.

(preparation of composite polarizing plate)

A commercially available sheet-like acrylic pressure-sensitive adhesive having a thickness of 25 μm was bonded to the 1 st protective layer side of the polarizing plate obtained in the above-described manner to form a1 st pressure-sensitive adhesive layer, and a triacetyl cellulose film (trade name "TJ 40 UL" manufactured by fuji film corporation) as a buffer layer was bonded to the 1 st pressure-sensitive adhesive layer on the side opposite to the polarizing plate side. Then, a commercially available sheet-like acrylic adhesive having a thickness of 25 μ M was applied to the opposite side of the cushion layer from the 1 st adhesive layer to form a2 nd adhesive layer, and a brightness enhancement film ("AFP-V3 HCS" manufactured by 3M) was applied to the opposite side of the 2 nd adhesive layer from the cushion layer. Then, the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (referred to as the 3 rd pressure-sensitive adhesive layer) of an acrylic pressure-sensitive adhesive having a thickness of 25 μm formed on a release film (a polyethylene terephthalate film having a thickness of 38 μm) was bonded to the 2 nd protective layer side of the polarizing plate. By the above operation, a composite polarizing plate in which a release film, a3 rd adhesive layer, a polarizing plate (a polarizing plate in which a2 nd protective layer, a linear polarizing layer, and a1 st protective layer are sequentially stacked from the 3 rd adhesive layer side), a1 st adhesive layer, a buffer layer, a2 nd adhesive layer, and a brightness enhancement film are sequentially stacked was obtained. In the case of bonding the materials, the bonding surfaces of the materials are subjected to corona treatment.

The in-plane retardation Re (590) at a wavelength of 590nm of the triacetyl cellulose film used as the buffer layer was measured, and found to be 0.5 nm. The tensile modulus of elasticity of the buffer layer at 23 ℃ and 55% relative humidity was 5200 MPa. As a result of the high-temperature durability test of the obtained composite polarizing plate, wrinkles were not observed in the brightness enhancement film, and the appearance of the composite polarizing plate was good.

[ comparative example 1]

A composite polarizing plate in which a release film, a3 rd pressure-sensitive adhesive layer, a polarizing plate (a polarizing plate in which a2 nd protective layer, a linear polarizing layer, and a1 st protective layer were sequentially stacked from the 3 rd pressure-sensitive adhesive layer side), a1 st pressure-sensitive adhesive layer, and a brightness enhancement film were sequentially stacked was obtained in the same manner as in example 1, except that the buffer layer and the 2 nd pressure-sensitive adhesive layer were not provided. The obtained composite polarizing plate was subjected to a high-temperature durability test, and as a result, a number of fine wrinkles were observed at the end portion of the long side of the brightness enhancement film.

Description of the reference numerals

1. 2 composite polarizing plate, 5, 6 liquid crystal display device, 10 polarizing plate, 11 linear polarizing layer, 12 st protective layer, 1 st protective layer, 13 nd protective layer, 15a, 15b buffer layer, 18 brightness enhancement film, 31 st adhesive layer, 32 nd adhesive layer, 2 nd adhesive layer, 33 rd adhesive layer, 3 rd adhesive layer, 35 peeling film, 41 liquid crystal unit, 42 backlight.

Claims (14)

1. A composite polarizing plate comprising a polarizing plate having a protective layer on at least one surface of a linear polarizing layer and a brightness enhancing film,

a1 st adhesive layer, a buffer layer, and the brightness enhancement film are sequentially laminated on the protective layer side of the polarizing plate,

the buffer layer has a tensile elastic modulus of 1.5GPa or more at a temperature of 23 ℃ and a relative humidity of 55%.

2. The composite polarizing plate of claim 1,

the buffer layer is attached to the brightness enhancement film via a2 nd adhesive layer.

3. The composite polarizing plate of claim 1 or 2,

the buffer layer is a resin film.

4. The composite polarizing plate of claim 3,

the resin film includes a film formed from at least 1 resin selected from a cellulose ester resin, a (meth) acrylic resin, and a cycloolefin resin.

5. The composite polarizing plate of claim 1,

the buffer layer is in direct contact with the brightness enhancement film.

6. The composite polarizing plate of claim 1 or 5,

the buffer layer is a cured product layer of a resin composition containing a curable component.

7. The composite polarizing plate of claim 6,

the curable component contains an active energy ray-curable compound.

8. The composite polarizing plate according to any one of claims 1 to 7,

the in-plane retardation Re (590) of the buffer layer at a wavelength of 590nm is 20nm or less.

9. The composite polarizing plate according to any one of claims 1 to 8,

the 1 st adhesive layer attaches the protective layer of the polarizing plate to the buffer layer.

10. The composite polarizing plate according to any one of claims 1 to 9,

the polarizing plate has the protective layer on both sides of the linear polarizing layer.

11. The composite polarizing plate according to any one of claims 1 to 10,

the polarizer plate had a3 rd adhesive layer on the side opposite the brightness enhancing film side.

12. The composite polarizing plate of claim 11,

the 3 rd adhesive layer has a release film on the side opposite to the polarizing plate side.

13. A liquid crystal display device having the composite polarizing plate according to any one of claims 1 to 12 and a liquid crystal cell.

14. The liquid crystal display device according to claim 13, further having a backlight,

the composite polarizing plate is disposed between the liquid crystal cell and the backlight such that the brightness enhancement film side is the backlight side.

Images