Polarizing plate

Abstract

To provide a polarizing plate which is excellent in peeling resistance at high temperature.SOLUTION: A polarizing plate includes a polarization laminate having a thermoplastic resin film A, a polarizer, and a (meth)acrylic resin film B in this order, and an adhesive layer provided on the (meth)acrylic resin film B of the polarization laminate. When the polarization laminate is exposed to environment at 80°C for 2 hours, the polarization laminate is curled so that the surface on the thermoplastic resin film A side becomes convex, and the (meth)acrylic resin film B becomes concave, or is not curled so that a maximum value of curling force of the polarization laminate during exposure to environment at 80°C for 2 hours is 3 N or less, and a dimension contraction rate in a transmission axial direction of the polarization laminate before and after being exposed to environment at 80°C for 144 hours is 1.25% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate. [Background technology]

[0002] Conventionally, polarizing plates having a laminated structure of protective film / polarizer / protective film / adhesive layer have been known. It has been proposed to use a (meth)acrylic resin film for at least one of the two protective films (see Patent Documents 1 and 2). Such polarizing plates are attached to liquid crystal cells or the like via the adhesive layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-105175 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-180422 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional polarizing plates, there is still room for improvement in peel resistance at high temperatures, particularly when a (meth)acrylic resin film is used as the protective film on the pressure-sensitive adhesive layer side.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a polarizing plate that has excellent peel resistance at high temperatures. [Means for solving the problem]

[0006] [1] A polarizing plate comprising: a polarizing laminate comprising a thermoplastic resin film A, a polarizer, and a (meth)acrylic resin film B in this order; and a pressure-sensitive adhesive layer provided on the (meth)acrylic resin film B of the polarizing laminate, When the polarizing laminate is exposed to an environment of 80°C for 2 hours, the polarizing laminate curls so that the surface on the thermoplastic resin film A side is convex and the surface on the (meth)acrylic resin film B is concave, or does not curl, the maximum curl force of the polarizing laminate during exposure to an environment of 80°C for 2 hours is 3N or less, A polarizing plate, wherein the polarizing laminate has a dimensional shrinkage rate in the transmission axis direction of 1.25% or less before and after exposure to an environment at 80°C for 144 hours. [2] The polarizing plate according to [1], wherein the thermoplastic resin film A is a polyester-based resin film or a (meth)acrylic-based resin film. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a polarizing plate that is excellent in peel resistance at high temperatures. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the vicinity of the surface 20A on the pressure-sensitive adhesive layer side of the (meth)acrylic resin film B (20) in FIG. [Figure 3] FIG. 2 is a schematic diagram showing a method for producing a (meth)acrylic resin film B according to one embodiment. [Figure 4] 4(a) and 4(b) are end views showing reverse curl and normal curl, respectively, of a polarizing laminate. [Figure 5] 5(a) and 5(b) are schematic diagrams relating to measurement of curling force. DETAILED DESCRIPTION OF THE INVENTION

[0009] Polarizing plates according to embodiments will be described below with reference to the drawings.

[0010] (polarizing plate) As shown in Fig. 1, the polarizing plate 100 has a pressure-sensitive adhesive layer 10 and a polarizing laminate 90. The polarizing laminate 90 has, in this order from the pressure-sensitive adhesive layer 10 side, a (meth)acrylic resin film B (20), a polarizer (30), and a thermoplastic resin film A (40). The pressure-sensitive adhesive layer 10 is in contact with the (meth)acrylic resin film B (20).

[0011] (1.1 Pressure-sensitive adhesive layer 10) The type of resin contained in the pressure-sensitive adhesive layer 10 is not particularly limited, and examples thereof include (meth)acrylic resins, silicone resins, urethane resins, rubber, etc. The resins can be used alone or in combination.

[0012] Among these, it is preferable to use a (meth)acrylic resin as the resin, since functionality can be easily imparted to the pressure-sensitive adhesive by selecting the type of monomer to be introduced into the resin. The structural units constituting this (meth)acrylic resin are also not limited. Hereinafter, the (meth)acrylic resin used in the pressure-sensitive adhesive layer will be referred to as (meth)acrylic resin α.

[0013] In this specification, "(meth)acrylic" means either acrylic or methacrylic. The "(meth)" in (meth)acrylate has the same meaning.

[0014] (1.2 (Meth)acrylic resin α) The (meth)acrylic resin α may be a polymer containing, as a main component, a structural unit derived from a (meth)acrylic acid ester (hereinafter also referred to as "monomer (II)") represented by the following formula (II):

[0015] In this specification, the term "polymer mainly composed of structural units derived from monomer (II)" means that the structural units derived from monomer (II) account for preferably 40% by mass or more, more preferably 60% by mass or more, for example 80% by mass or more of the total structural units constituting the polymer. In this case, the structural units derived from monomer (II) account for usually 100% by mass or less, preferably 90% by mass or less of the total structural units constituting the polymer.

[0016] [ka]

[0017] In the monomer (II), R 3 is a hydrogen atom or a methyl group, and R 4 is usually an alkyl or aralkyl group having 14 or less carbon atoms, preferably 10 or less carbon atoms.

[0018] Of the monomers (II), R 4 More specific examples of alkyl groups include linear acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, and lauryl acrylate; branched acrylic acid alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; linear methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; and branched methacrylic acid alkyl esters such as isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate.

[0019] Of these, n-butyl acrylate is preferred, and specifically, it is preferred that n-butyl acrylate accounts for 50 mass % or more of all structural units (monomers) constituting the (meth)acrylic resin (A).

[0020] Of the monomers (II), R4 Specific examples of aralkyl groups include benzyl acrylate and benzyl methacrylate.

[0021] These monomers (II) can be used alone or in combination.

[0022] R in monomer (II) 4 The alkyl or aralkyl group that constitutes the above group is one in which the hydrogen atom is not substituted with the group -O-(C2H4O) n -R 5 It may be substituted with.

[0023] R in the formula (II) 4 The hydrogen atoms of the alkyl or aralkyl groups that make up the group -O-(C2H4O) n -R 5 When R is substituted with R, n is preferably 0 or an integer of 1 to 4, and more preferably 0, 1, or 2. 5 is an alkyl group or aryl group having 12 or less carbon atoms, and may be linear or branched as long as the alkyl group has 3 or more carbon atoms. R 5 Examples of aryl groups that make up R include phenyl and naphthyl, as well as tolyl, xylyl, ethylphenyl, and other alkyl-substituted phenyls, biphenylyl (or phenylphenyl), etc. 5 is particularly preferably an aryl group.

[0024] R in formula (II) 4 is an alkyl group or an aralkyl group, and R 4 The hydrogen atom of the alkyl or aralkyl group is the group -O-(C2H4O) n -R 5Specific examples of the (meth)acrylic acid ester substituted with include alkoxyalkyl esters, aryloxyalkyl esters, and aryloxyethoxyalkyl esters of acrylic acid such as 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2-(2-phenoxyethoxy)ethyl acrylate, and 2-(o-phenylphenoxy)ethyl acrylate; and alkoxyalkyl esters, aryloxyalkyl esters, and aryloxyethoxyalkyl esters of methacrylic acid such as 2-methoxyethyl methacrylate, ethoxymethyl methacrylate, 2-phenoxyethyl methacrylate, 2-(2-phenoxyethoxy)ethyl methacrylate, and 2-(o-phenylphenoxy)ethyl methacrylate.

[0025] The (meth)acrylic resin α preferably contains, as structural units derived from (meth)acrylic acid alkyl esters, a structural unit derived from an acrylic acid alkyl ester (a1) whose homopolymer has a glass transition temperature of less than 0°C, and a structural unit derived from an acrylic acid alkyl ester (a2) whose homopolymer has a glass transition temperature of 0°C or higher. The pressure-sensitive adhesive composition containing the (meth)acrylic resin α containing structural units derived from the acrylic acid alkyl esters (a1) and (a2) can be advantageous for obtaining a polarizing plate with improved peel resistance at high temperatures. The glass transition temperature of the acrylic acid alkyl ester homopolymer can be determined from literature values ​​such as those in POLYMER HANDBOOK (Wiley-Interscience).

[0026] Examples of the alkyl acrylate (a1) include alkyl acrylates having an alkyl group having about 2 to 12 carbon atoms, such as ethyl acrylate, n-propyl acrylate and i-propyl acrylate, n-butyl acrylate and i-butyl acrylate, n-pentyl acrylate, n-hexyl acrylate and i-hexyl acrylate, n-heptyl acrylate, n-octyl acrylate and i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate and i-nonyl acrylate, n-decyl acrylate and i-decyl acrylate, and n-dodecyl acrylate. Other specific examples of the alkyl acrylate (a1) include substituted alkyl acrylates in which a substituent has been introduced into the alkyl group of an alkyl acrylate having about 2 to 12 carbon atoms. The substituent of the substituted alkyl acrylate is a group that substitutes a hydrogen atom of the alkyl group, and specific examples thereof include a phenyl group, an alkoxy group, and a phenoxy group. Specific examples of the substituted alkyl acrylate include 2-methoxyethyl acrylate, ethoxymethyl acrylate, phenoxyethyl acrylate, and phenoxydiethylene glycol acrylate. The alkyl group of the alkyl acrylate (a1) is preferably a linear or branched alkyl group.

[0027] The acrylic acid alkyl ester (a1) may be used alone or in combination of two or more. Among them, the acrylic acid alkyl ester (a1) preferably contains one or more selected from ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. From the viewpoint of peel resistance at high temperatures, the acrylic acid alkyl ester (a1) preferably contains n-butyl acrylate.

[0028] From the viewpoint of peel resistance at high temperatures, the content of structural units derived from the acrylic acid alkyl ester (a1) in the (meth)acrylic resin α is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, relative to 100% by mass of all structural units constituting the (meth)acrylic resin α, and is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 81% by mass or less.

[0029] The alkyl acrylate (a2) is an alkyl acrylate other than the alkyl acrylate (a1). Examples of the alkyl acrylate (a2) include methyl acrylate, stearyl acrylate, and t-butyl acrylate.

[0030] The acrylic acid alkyl ester (a2) may be used alone or in combination of two or more. Among them, from the viewpoint of peel resistance at high temperatures, the acrylic acid alkyl ester (a2) preferably contains methyl acrylate.

[0031] From the viewpoint of peel resistance at high temperatures, the content of the structural units derived from the acrylic acid alkyl ester (a2) in the (meth)acrylic resin (A) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to 100% by mass of all structural units constituting the (meth)acrylic resin (A), and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0032] In the (meth)acrylic resin α, the total content of the structural units derived from the acrylic acid alkyl ester (a1) and the structural units derived from the acrylic acid alkyl ester (a2) is preferably 60 mass% or more, more preferably 70 mass% or more, and even more preferably 80 mass% or more, based on 100 mass% of all structural units constituting the (meth)acrylic resin α, and is preferably 99.9 mass% or less, and may be 99.5 mass% or less, or may be 99 mass% or less.

[0033] In one embodiment of the present invention, the (meth)acrylic resin α may contain, in addition to structural units derived from (meth)acrylic acid esters, other structural units, particularly structural units derived from monomers having polar functional groups, preferably structural units derived from (meth)acrylic acid compounds having polar functional groups. Examples of polar functional groups include carboxyl groups, hydroxyl groups, amino groups, and heterocyclic groups such as epoxy rings. Examples of (meth)acrylic acid compounds having polar functional groups include (meth)acrylic acid, 2-(dimethylamino)ethyl acrylate, 2-hydroxyethyl (meth)acrylate, and glycidyl acrylate.

[0034] The (meth)acrylic resin α may contain structural units derived from monomers having polar functional groups in an amount of preferably 20% by mass or less, more preferably 10% by mass or less, for example 5% by mass or less, based on all structural units constituting the polymer.

[0035] Furthermore, the (meth)acrylic resin α may contain a structural unit derived from a monomer other than the monomer (II) that does not have a polar functional group. Suitable structural units (monomers) include structural units derived from a monomer having one olefinic double bond and at least one aromatic ring in the molecule, preferably structural units derived from a (meth)acrylic acid compound having an aromatic ring. In this specification, (meth)acrylic acid means either acrylic acid or methacrylic acid, and the "(meth)" in (meth)acrylate and the like has the same meaning.

[0036] Other examples of the monomer other than the monomer (II) and not having a polar functional group include (meth)acrylic acid ester monomers having an alicyclic structure in the molecule, styrene-based monomers, vinyl-based monomers, (meth)acrylamide derivatives, and monomers having multiple (meth)acryloyl groups in the molecule.

[0037] (Meth)acrylic acid ester monomers having an alicyclic structure in the molecule will be described. The alicyclic structure is a cycloparaffin structure having typically 5 or more carbon atoms, preferably about 5 to 7. Specific examples of acrylic acid ester monomers having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, and cyclohexylphenyl acrylate. Specific examples of methacrylic acid ester monomers having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, and cyclohexylphenyl methacrylate.

[0038] Examples of styrene-based monomers include, in addition to styrene, alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and further, nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, and the like.

[0039] Examples of vinyl monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile, methacrylonitrile, and the like.

[0040] Examples of (meth)acrylamide derivatives include N-methylol (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-(5-hydroxypentyl) (meth)acrylamide, N-(6-hydroxyhexyl) (meth)acrylamide, N-(methoxymethyl) (meth)acrylamide, N-(ethoxymethyl) (meth)acrylamide, and N-(propoxymethyl) (meth)acrylamide. )(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2-acryloylamino-2-methyl-1-propanesulfonic acid, etc.

[0041] Examples of monomers having multiple (meth)acryloyl groups in the molecule include monomers having two (meth)acryloyl groups in the molecule, such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; and monomers having three (meth)acryloyl groups in the molecule, such as trimethylolpropane tri(meth)acrylate.

[0042] The (meth)acrylic resin α may contain structural units derived from a monomer other than the monomer (II) and not having a polar functional group in an amount of preferably 20% by mass or less, more preferably 10% by mass or less, for example 5% by mass or less, based on all structural units constituting the polymer.

[0043] The monomer constituting the (meth)acrylic resin α may be a mixture of any two or more selected from the group consisting of the (meth)acrylic acid ester monomer (II), a monomer having a polar functional group, and a monomer other than the monomer (II) that does not have a polar functional group.

[0044] The weight-average molecular weight (Mw) of the resin contained in the adhesive, measured by gel permeation chromatography (GPC) in terms of standard polystyrene, is not particularly limited, but is preferably in the range of 500,000 to 2,000,000, and more preferably in the range of 500,000 to 1,800,000. A weight-average molecular weight (Mw) of 500,000 or more in terms of standard polystyrene improves adhesion under high-temperature and high-humidity conditions, tends to reduce the likelihood of lifting or peeling between the glass substrate and the adhesive layer, and also tends to improve reworkability. Furthermore, a weight-average molecular weight of 2,000,000 or less is preferred because the adhesive layer follows the dimensional changes of the resin film attached to the adhesive layer, eliminating the difference in brightness between the periphery and center of the liquid crystal cell and tending to suppress whiteout and color unevenness. The molecular weight distribution, expressed as the ratio Mw / Mn of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is not particularly limited, but is preferably in the range of, for example, approximately 3 to 15.

[0045] The resin contained in the pressure-sensitive adhesive can be produced by various known methods, such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. A polymerization initiator may be used in the production of the resin, and the amount added is about 0.001 to 5 parts by mass per 100 parts by mass of the total of all monomers used in the production of the resin.

[0046] The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone. Examples of the thermal polymerization initiator include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); lauryl peroxide. Examples of the polymerization initiator include organic peroxides such as tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl)peroxide; and inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Redox initiators using a combination of a peroxide and a reducing agent can also be used as the polymerization initiator.

[0047] Among the methods listed above, solution polymerization is preferred as a method for producing the (meth)acrylic resin α. A specific example of solution polymerization involves mixing the desired monomers and an organic solvent, adding a thermal polymerization initiator under a nitrogen atmosphere, and stirring for 3 to 15 hours at approximately 40 to 90°C, preferably approximately 50 to 80°C. To control the reaction, the monomers and the thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a dissolved state in an organic solvent. Examples of organic solvents that can be used include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0048] (1.3 Ionic Compounds) The pressure-sensitive adhesive layer may contain an ionic compound. The ionic compound may function as an antistatic agent. The ionic compound is a compound having an inorganic cation or an organic cation and an inorganic anion or an organic anion. The pressure-sensitive adhesive layer 10 may contain two or more types of ionic compounds.

[0049] Examples of inorganic cations include lithium cations [Li + ], sodium cation [Na + ], potassium cation [K + ] and beryllium cations [Be 2+ ], magnesium cation [Mg 2+ ], calcium cation [Ca 2+ Examples of the organic cation include imidazolium cation, pyridinium cation, pyrrolidinium cation, ammonium cation, sulfonium cation, and phosphonium cation. Organic cation components are preferably used because they have excellent compatibility with the base polymer.

[0050] Examples of inorganic anions include chloride anions [Cl - ], bromide anion [Br - ], iodide anion [I - ], tetrachloroaluminate anion [AlCl4 - ], heptachlorodialuminate anion [Al2Cl7 - ], tetrafluoroborate anion [BF4 - ], hexafluorophosphate anion [PF6 - ], perchlorate anion [ClO4 - ], nitrate anion [NO3 - ], hexafluoroarsenate anion [AsF6 - ], hexafluoroantimonate anion [SbF6 -], hexafluoroniobate anion [NbF6 - ], hexafluorotantalate anion [TaF6 - ], dicyanamide anion [(CN)2N - ] etc.

[0051] The organic anion is, for example, an acetate anion [CH3COO - ], trifluoroacetate anion [CF3COO - ], methanesulfonate anion [CH3SO3 - ], trifluoromethanesulfonate anion [CF3SO3 - ], p-toluenesulfonate anion〔p-CH3C6H4SO3 - ], bis(fluorosulfonyl)imide anion [(FSO2)2N - ], bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - ], tris(trifluoromethanesulfonyl)methanide anion [(CF3SO2)3C - ], dimethylphosphinate anion [(CH3)2POO - ], (poly)hydrofluorofluoride anion [F(HF) n - ](n is about 1 to 3), thiocyanate anion [SCN - ], perfluorobutanesulfonate anion [C4F9SO3 - ], bis(pentafluoroethanesulfonyl)imide anion [(C2F5SO2)2N - ], perfluorobutanoate anion [C3F7COO - ], (trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF3SO2)(CF3CO)N - ], perfluoropropane-1,3-disulfonate anion〔-O3S(CF2)3SO3 - ], carbonate anion [CO3 2- ] etc.

[0052] Among the above-mentioned anion components, anion components containing fluorine atoms are particularly preferred because they provide ionic compounds with excellent antistatic properties. Specific examples include bis(fluorosulfonyl)imide anion, hexafluorophosphate anion, and bis(trifluoromethanesulfonyl)imide anion.

[0053] Specific examples of the ionic compound can be appropriately selected from the combinations of the cation component and the anion component described above. Examples of ionic compounds having an organic cation, classified according to the structure of the organic cation, include the following:

[0054] Pyridinium salts: N-octyl-4-methylpyridinium hexafluorophosphate, N-hexylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-butyl-4-methylpyridinium hexafluorophosphate, N-decylpyridinium bis(fluorosulfonyl)imide, N-dodecylpyridinium bis(fluorosulfonyl)imide, N-tetradecylpyridinium bis(fluorosulfonyl)imide, N-hexadecylpyridinium bis(fluorosulfonyl)imide, N-dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-benzyl-2-methylpyridinium bis(fluorosulfonyl)imide, N-Benzyl-4-methylpyridinium bis(fluorosulfonyl)imide N-hexylpyridinium bis(trifluoromethanesulfonyl)imide, N-octylpyridinium bis(trifluoromethanesulfonyl)imide, N-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide, N-Butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide.

[0055] Imidazolium salts: 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium methanesulfonate, 1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide.

[0056] Pyrrolidinium salts: N-butyl-N-methylpyrrolidinium hexafluorophosphate, N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide, N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0057] Quaternary ammonium salts: tetrabutylammonium hexafluorophosphate, tetrabutylammonium p-toluenesulfonate, (2-hydroxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide, (2-Hydroxyethyl)trimethylammonium dimethylphosphinate.

[0058] Examples of ionic compounds having inorganic cations include the following: lithium bromide, lithium iodide, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium thiocyanate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(pentafluoroethanesulfonyl)imide, lithium tris(trifluoromethanesulfonyl)methanide, lithium p-toluenesulfonate, sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium p-toluenesulfonate, potassium hexafluorophosphate, potassium bis(fluorosulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, Potassium p-toluenesulfonate.

[0059] Of these ionic compounds, pyridinium salts are preferred from the viewpoint of high temperature durability, which is an effect of the present invention, and of the pyridinium salts, N-octyl-4-methylpyridinium hexafluorophosphate is more preferred.

[0060] The ionic compound is preferably a solid at room temperature. Compared with the use of an ionic compound that is liquid at room temperature, the antistatic performance can be maintained for a longer period of time. From the viewpoint of long-term stability of the antistatic property, the ionic compound preferably has a melting point of 30°C or higher, more preferably 35°C or higher. On the other hand, if the melting point is too high, the compatibility with the base polymer deteriorates. Therefore, the melting point is preferably 90°C or lower, more preferably 70°C or lower, and even more preferably lower than 50°C.

[0061] The content of the ionic compound is usually from 0.2 to 8 parts by mass, preferably from 0.3 to 5 parts by mass, more preferably from 0.5 to 5 parts by mass, even more preferably from 0.5 to 4 parts by mass, and particularly preferably from 1 to 3.5 parts by mass, relative to 100 parts by mass of the resin (base polymer) contained in the pressure-sensitive adhesive layer 10. Having the content of the ionic compound within the above range is advantageous for achieving both sufficient antistatic performance and maintaining the durability of the pressure-sensitive adhesive layer.

[0062] (1.4 Additives) The pressure-sensitive adhesive layer may contain other additives in addition to the resin and the ionic compound, such as a crosslinking agent, a silane compound, a crosslinking catalyst, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, an organic acid, and a metal salt of an organic acid.

[0063] Furthermore, it is also useful to blend an ultraviolet-curable compound with the pressure-sensitive adhesive and, after the pressure-sensitive adhesive layer is formed, to cure it by irradiating it with ultraviolet light to form a harder pressure-sensitive adhesive layer. That is, the pressure-sensitive adhesive may be an active energy ray-curable or heat-curable pressure-sensitive adhesive.

[0064] (1.5 Crosslinker) The crosslinking agent that can be contained in the pressure-sensitive adhesive is a compound having at least two functional groups in the molecule that can crosslink the resin contained in the pressure-sensitive adhesive, such as an isocyanate compound, an epoxy compound, a metal chelate compound, and an aziridine compound.

[0065] The isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule, and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, as well as dimers, trimers, and the like of isocyanate compounds, can also be used as crosslinking agents for adhesives. Two or more isocyanate compounds can also be used in combination.

[0066] The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include bisphenol A epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, etc. Two or more epoxy compounds can also be used in combination.

[0067] Examples of metal chelate compounds include compounds in which acetylacetone or ethyl acetoacetate is coordinated with a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, or zirconium.

[0068] Aziridine compounds are compounds that have at least two three-membered ring skeletons, each consisting of one nitrogen atom and two carbon atoms, also known as ethyleneimines, within the molecule. Examples include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane tris-β-aziridinylpropionate, and tetramethylolmethane tris-β-aziridinylpropionate.

[0069] Of these crosslinking agents, isocyanate compounds, particularly an adduct obtained by reacting tolylene diisocyanate with a polyol, a dimer of tolylene diisocyanate, a trimer of tolylene diisocyanate, an adduct obtained by reacting hexamethylene diisocyanate with a polyol, a dimer of hexamethylene diisocyanate, a trimer of hexamethylene diisocyanate, an adduct obtained by reacting xylene diisocyanate with a polyol, an adduct obtained by reacting hydrogenated xylylene diisocyanate with a polyol, isophorone diisocyanate and / or an adduct obtained by reacting isophorone diisocyanate with a polyol, and mixtures of these isocyanate compounds are preferably used.

[0070] The content of the crosslinking agent in the adhesive is usually about 0.01 to 5 parts by mass, preferably 0.03 to 2 parts by mass, and more preferably 0.1 to 1.5 parts by mass, per 100 parts by mass of the resin contained in the adhesive.

[0071] (1.6 Silane-based compounds) In the case where a resin film with adhesive or a polarizing plate with adhesive is formed and then laminated to a glass substrate, the adhesive layer preferably contains a silane-based compound from the viewpoint of improving adhesion to the glass substrate.

[0072] Examples of silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane, etc. Two or more silane compounds may be used.

[0073] The silane-based compound may be a silicone oligomer type. When the silicone oligomer is expressed in the form of a (monomer)-(monomer) copolymer, for example, the following can be mentioned:

[0074] mercaptopropyl group-containing copolymers such as 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer;

[0075] mercaptomethyl group-containing copolymers such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer;

[0076] methacryloyloxypropyl group-containing copolymers such as 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0077] acryloyloxypropyl group-containing copolymers such as 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0078] vinyl group-containing copolymers such as vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;

[0079] The silicone oligomer may have a siloxane main chain and a plurality of mercapto groups and alkoxy groups on the side chains, and the alkoxy groups are preferably methoxy groups.

[0080] These silane compounds are often liquids. The content of the silane compound in the adhesive is usually about 0.01 to 10 parts by mass, preferably 0.03 to 2 parts by mass, and more preferably 0.03 to 1 part by mass, per 100 parts by mass of the resin contained in the adhesive.

[0081] The thickness of the pressure-sensitive adhesive layer 10 is, for example, 250 μm or less, and from the viewpoint of thinning, is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less. From the viewpoint of durability, the lower limit of the thickness of the pressure-sensitive adhesive layer is, for example, 1 μm or more, preferably 5 μm or more, and more preferably 10 μm or more.

[0082] There are no particular limitations on the storage modulus of the pressure-sensitive adhesive layer 10. The storage modulus of the pressure-sensitive adhesive layer 10 at 25°C may be 0.085 to 0.14 MPa, and preferably 0.09 to 0.12 MPa. The storage modulus at 60°C may be 0.060 to 0.099 MPa, and preferably 0.073 to 0.083 MPa. The storage modulus can be adjusted by adjusting the composition of the pressure-sensitive adhesive layer (the composition of the (meth)acrylic resin α, the type and amount of crosslinking agent, silane compound, etc.).

[0083] (2) (Meth)acrylic resin film B (20) (2.1 Materials) First, the material of the (meth)acrylic resin film B (20) will be described.

[0084] The (meth)acrylic resin film B(20) contains a (meth)acrylic resin and may further contain rubber elastomer particles. When the (meth)acrylic resin film B(20) contains rubber elastomer particles, the (meth)acrylic resin phase forms a continuous phase, and the rubber elastomer particles form a dispersed phase dispersed in the (meth)acrylic resin phase. Here, the term "(meth)acrylic resin" is a concept that includes both acrylic resins and methacrylic resins.

[0085] (2.2 (Meth)acrylic resin) A (meth)acrylic resin is a polymer whose main structural unit (50% by mass or more of the total structural units) is a (meth)acrylic acid ester, particularly a (meth)acrylic acid alkyl ester. This resin may be a homopolymer of a (meth)acrylic acid ester, a copolymer using two or more (meth)acrylic acid esters, or even a copolymer of a (meth)acrylic acid ester and a monomer copolymerizable therewith. In this specification, (meth)acrylic acid means acrylic acid and / or methacrylic acid. Similarly, a (meth)acrylic acid ester means an acrylic acid ester and / or a methacrylic acid ester.

[0086] Specific examples of (meth)acrylic acid esters include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, and dodecyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, and dodecyl methacrylate.

[0087] These (meth)acrylic acid alkyl esters may have an optional substituent such as a hydroxyl group or a halogen atom in the alkyl moiety. Examples of (meth)acrylic acid alkyl esters having such a substituent include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, and glycidyl methacrylate.

[0088] Among these (meth)acrylic acid esters, methyl methacrylate is preferably used as the main raw material of the acrylic resin. That is, as will be specifically described later, a homopolymer of methyl methacrylate, a copolymer of methyl methacrylate as the main constituent monomer with other (meth)acrylic acid esters, a copolymer of methyl methacrylate as the main constituent monomer with other monomers other than (meth)acrylic acid esters, or a copolymer of methyl methacrylate as the main constituent monomer with other (meth)acrylic acid esters and monomers other than (meth)acrylic acid esters are suitable as the (meth)acrylic resin.

[0089] Examples of monomers copolymerizable with (meth)acrylic acid esters include α,β-ethylenically unsaturated carboxylic acid esters other than the above-mentioned (meth)acrylic acid esters, α,β-ethylenically unsaturated carboxylic acids, alkenyl aromatic compounds, conjugated dienes, non-conjugated dienes, vinyl cyanide, α,β-ethylenically unsaturated carboxylic acid amides, unsaturated alcohol carboxylic acid esters, and olefins.

[0090] Specific examples of α,β-ethylenically unsaturated carboxylic acid esters other than (meth)acrylic acid esters include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, monoethyl maleate, monobutyl fumarate, etc. The α,β-ethylenically unsaturated carboxylic acid may be any of a monocarboxylic acid, a polycarboxylic acid, and a polycarboxylic acid anhydride, and specific examples thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride.

[0091] Specific examples of alkenyl aromatic compounds include styrene, α-methylstyrene, α-methyl-2-, α-methyl-3-, or α-methyl-4-methylstyrene, vinyltoluene, and divinylbenzene.Specific examples of conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, and cyclopentadiene.Specific examples of non-conjugated dienes include 1,4-hexadiene, dicyclopentadiene, and ethylidenenorbornene.

[0092] Specific examples of vinyl cyanides include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and α-ethylacrylonitrile. Specific examples of α,β-ethylenically unsaturated carboxylic acid amides include acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, and N,N-dimethylacrylamide. Specific examples of unsaturated carboxylic acid alcohol esters include vinyl acetate. Specific examples of olefins include ethylene, propylene, butene, and pentene.

[0093] When a monomer other than a (meth)acrylic acid ester is copolymerized, only one type of monomer other than a (meth)acrylic acid ester may be copolymerized, or two or more types of monomers other than a (meth)acrylic acid ester may be copolymerized. When such a monomer other than a (meth)acrylic acid ester is copolymerized, the content of structural units derived from such monomers in the (meth)acrylic resin is preferably 50% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less of all structural units.

[0094] Specific examples of (meth)acrylic resins suitable for use in the present invention include poly(methyl methacrylate), methyl methacrylate / methyl acrylate copolymers, methyl methacrylate / methyl acrylate / butyl acrylate / styrene copolymers, methyl methacrylate / styrene / butyl acrylate copolymers, and methyl methacrylate / ethylene copolymers. Among these, polymers in which structural units derived from methyl methacrylate account for 70% by mass or more, preferably 80% by mass or more, and particularly 90% by mass or more of the total structural units are preferred. One (meth)acrylic resin may be used alone, or two or more types may be used in combination. The molecular weight of the (meth)acrylic resin, as calculated as a weight-average molecular weight in terms of polystyrene, is, for example, about 50,000 to 500,000. A weight-average molecular weight within this range facilitates the production of a homogeneous film when formed by melt extrusion.

[0095] When the (meth)acrylic resin has a ring structure in its main chain, the heat resistance and hardness of the final (meth)acrylic resin film can be improved. When the (meth)acrylic resin has a ring structure in its main chain, the ring structure content in the resin can generally be in the range of 0.1 to 99 mass%, 1 to 95 mass%, 2 to 93 mass%, or 5 to 90 mass%, but a range of 10 to 70 mass%, further 10 to 60 mass%, and particularly 10 to 50 mass% is preferred in order to improve the heat resistance and hardness while maintaining appropriate stretchability and handleability of the (meth)acrylic resin film. If the ring structure content is too high, the stretchability and handleability of the (meth)acrylic resin film will be reduced.

[0096] Examples of the ring structure that the (meth)acrylic resin may have in the main chain include a glutarimide structure, a lactone ring structure, a succinic anhydride structure, and a succinimide structure.

[0097] (Meth)acrylic resins having a ring structure in the main chain are commercially available, and can also be produced by known methods.

[0098] The (meth)acrylic resin may be a mixture of multiple types of methacrylic resins.

[0099] In the (meth)acrylic resin film, the amount of the (meth)acrylic resin may be 10% by mass or more, 20% by mass or more, 40% by mass or more, 50% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass, based on the total mass.

[0100] (2.3 Rubber elastomer particles) The (meth)acrylic resin film may contain rubber elastomer particles. When the (meth)acrylic resin film contains rubber elastomer particles, the rubber elastomer particles may be dispersed in the (meth)acrylic resin phase. The rubber elastomer particles are particles containing a rubber elastomer. Examples of rubber elastomer particles that can be blended include rubber polymers whose main constituent monomer is an acrylic acid ester, rubber polymers whose main constituent monomer is butadiene, and ethylene-vinyl acetate copolymers. Among these, acrylic rubber particles, which are rubber polymers whose main constituent monomer is an acrylic acid ester, are preferred. Of course, acrylic rubber particles may be used in combination with other rubber elastomer particles.

[0101] The acrylic rubber particles may be those whose main constituent monomer is an alkyl acrylate ester having a large number of carbon atoms in the alkyl group, for example, about 4 to 8 carbon atoms, such as butyl acrylate or 2-ethylhexyl acrylate. Among these, an elastomeric polymer whose main constituent monomer is butyl acrylate is preferred. While rubber particles having a single-layer structure made of an elastomeric polymer whose main constituent monomer is an alkyl acrylate ester may be used, multilayer rubber particles including a layer of the elastomeric polymer are also effective. A typical example of the latter is a rubber particle having a core-shell structure in which a layer of an acrylic elastomeric polymer, such as a grafted elastomeric polymer of an alkyl acrylate such as butyl acrylate and styrene, and a layer of a hard polymer whose main constituent monomer is methyl methacrylate are layered together. More specifically, there are rubber particles having a two-layer structure in which a layer of the hard polymer is formed on the outside of an acrylic elastomeric polymer, and a three-layer structure in which a layer of the hard polymer is formed on the inside of an acrylic elastomeric polymer and another layer of the hard polymer is formed on the outside of the acrylic elastomeric polymer. The term "main constituent monomer" refers to a monomer whose mass ratio in the polymer is more than 50%, and may be 70% or more, or 80% or more.

[0102] In particular, those containing acrylic rubber particles with such a multilayer structure are cited as suitable examples of rubber elastic particles.

[0103] The rubber particles dispersed in the (meth)acrylic resin preferably have a number-average particle size of 1,000 nm or less, more preferably in the range of 100 to 1,000 nm, and even more preferably in the range of 100 to 500 nm. If the number-average particle size of the rubber particles is too large, the haze of the film becomes too large, resulting in a low light transmittance. On the other hand, if the number-average particle size is too small, the flexibility of the film tends to decrease.

[0104] The average particle size of acrylic rubber particles containing acrylic rubber particles is measured as follows. Specifically, when such rubber particles are blended with a (meth)acrylic resin to form a film and the cross section is stained with an aqueous solution of ruthenium oxide, only the acrylic elastomeric polymer layer is colored and observed as a nearly circular shape, while the acrylic resin in the base layer is not stained. Therefore, a thin section is prepared from the cross section of the dyed film using a microtome or the like and observed under an electron microscope. Then, 100 dyed elastomeric polymer particles are randomly selected, and the particle size of each is calculated. The number average value is taken as the average particle size. Because this method is used, the average particle size of rubber particles defined here is the number average particle size.

[0105] When rubber particles are used, the outermost layer of which is a hard polymer primarily composed of methyl methacrylate and which contains an acrylic elastomeric polymer, and when the rubber particles are mixed with a (meth)acrylic resin, the outermost layer of the rubber particles is mixed with the acrylic matrix resin. Therefore, when the cross-section is stained with ruthenium oxide and observed under an electron microscope, the rubber particles are observed as particles without the outermost layer. Specifically, when a two-layer rubber particle is used, where the inner layer is an acrylic elastomeric polymer and the outer layer is a hard polymer primarily composed of methyl methacrylate, the acrylic elastomeric polymer portion of the inner layer is stained and observed as a single-layer particle. On the other hand, when a three-layer rubber particle is used, where the innermost layer is a hard polymer primarily composed of methyl methacrylate, the middle layer is an acrylic elastomeric polymer, and the outermost layer is a hard polymer primarily composed of methyl methacrylate, the center of the innermost layer is not stained, and only the acrylic elastomeric polymer portion of the middle layer is stained, and observed as a two-layer particle.

[0106] The amount of rubber elastomer particles added to the (meth)acrylic resin is preferably 10 to 50 mass %, more preferably 10 to 40 mass %, based on the total amount of the (meth)acrylic resin film blended with the rubber elastomer particles. If the amount of rubber elastomer particles is too small, the film will not have sufficient slip properties and flexibility, and if the amount is too large, the film will not have sufficient heat resistance.

[0107] The composition constituting the acrylic resin film may be produced, for example, by obtaining rubber elastomer particles and then polymerizing a monomer that serves as a raw material for the acrylic resin in the presence of the rubber elastomer particles to produce the base acrylic resin, or by obtaining rubber elastomer particles and an acrylic resin and then mixing the two by melt kneading or the like.

[0108] (2.4 Other Materials) The acrylic resin film may contain additives such as colorants such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, and solvents, as needed.

[0109] UV absorbers are added to improve durability by absorbing UV rays of 400 nm or less. Known UV absorbers, such as benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and acrylonitrile-based UV absorbers, can be used. Among them, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol), 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone are preferred. Among these, 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol) is particularly preferred.

[0110] The concentration of the ultraviolet absorber can be selected within a range such that the transmittance of the acrylic resin film at wavelengths of 370 nm or less is preferably 10% or less, more preferably 5% or less, and even more preferably 2% or less. Methods for incorporating the ultraviolet absorber include blending the ultraviolet absorber into the acrylic resin in advance and directly supplying it during melt extrusion molding, and either method may be employed.

[0111] Examples of infrared absorbers include nitroso compounds, their metal complexes, cyanine compounds, squarylium compounds, thiol nickel complexes, phthalocyanine compounds, naphthalocyanine compounds, triarylmethane compounds, immonium compounds, diimmonium compounds, naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, carbon black, indium tin oxide, antimony tin oxide, and oxides, carbides, and borides of metals belonging to Group 4A, 5A, or 6A of the Periodic Table. These infrared absorbers are preferably selected so as to absorb all infrared rays (light with wavelengths of approximately 800 nm to 1100 nm), and two or more types may be used in combination. The amount of infrared absorber can be appropriately adjusted, for example, so that the light transmittance of the acrylic resin film at wavelengths of 800 nm or more is 10% or less.

[0112] (2.5 Structure of Film B when Rubber Elastomer Particles are Contained) Fig. 2 is an enlarged schematic cross-sectional view of a surface 20A of the (meth)acrylic resin film B(20) on the pressure-sensitive adhesive layer 10 side when the (meth)acrylic resin film B(20) contains rubber elastomer particles. As shown in Fig. 2, the (meth)acrylic resin film 20 may contain a (meth)acrylic resin phase 20a forming a continuous phase and rubber elastomer particles 20b as a dispersed phase dispersed in the (meth)acrylic resin phase 20a.

[0113] As shown in Figure 2, on the surface 20A of the (meth)acrylic resin film B on the pressure-sensitive adhesive layer 10 side, some of the rubber elastomer particles 20b protrude from the surface 20Ab of the (meth)acrylic resin phase 20a to form a protruding surface 20Aa. That is, the surface 20A of the (meth)acrylic resin film 20 on the side that comes into contact with the adhesive layer 10 is formed from a planar surface 20Ab of the (meth)acrylic resin phase 20a and a convex surface 20Aa of the rubber elastomer particles 20b protruding from the planar surface 20Ab, and has an uneven shape.

[0114] In this embodiment, the arithmetic mean roughness (Ra) of the surface 20A of the (meth)acrylic resin film B (20) on the side in contact with the pressure-sensitive adhesive layer 10 may be 8 nm or more, 9 nm or more, or 10 nm or more. There is no particular upper limit to the arithmetic mean roughness (Ra), but it may be, for example, 20 nm or less, or 15 nm or less.

[0115] The arithmetic mean roughness Ra is based on JIS B 0601-2001.

[0116] There are no particular limitations on the state of the surface 20B of the (meth)acrylic resin film B (20) that faces the polarizer on the side opposite to the side that comes into contact with the pressure-sensitive adhesive layer 10.

[0117] For example, surface 20B may be formed from a planar surface of the (meth)acrylic resin phase and convex surfaces of rubber elastomer particles protruding from the planar surface, similar to surface 20A, and may have an uneven shape. Alternatively, surface 20B may have only a planar surface of the (meth)acrylic resin phase, and may not have convex surfaces of rubber elastomer particles protruding from the planar surface.

[0118] The arithmetic mean roughness (Ra) of surface 20B may be the same as the arithmetic mean roughness (Ra) of surface 20A, may be greater than the arithmetic mean roughness (Ra) of surface 20A, or may be smaller than the arithmetic mean roughness (Ra) of surface 20A.

[0119] The arithmetic mean roughness (Ra) of surface 20B is preferably smaller than the arithmetic mean roughness (Ra) of surface 20A. There are no particular limitations on the arithmetic mean roughness (Ra) of surface 20B, but it is preferably less than 8 nm, and may be less than 5 nm or even less than 4 nm. As will be described later, a (meth)acrylic resin film containing a rubber elastomer is likely to have an uneven surface on one side and a smooth surface on the other side, depending on the manufacturing method. The uneven surface has a larger surface area due to the rubber elastomer particles than the smooth surface, resulting in a larger arithmetic mean roughness (Ra). However, the smooth surface tends to experience a greater increase in unevenness (surface roughness) when exposed to high temperatures than the uneven surface. In such a (meth)acrylic resin film, contacting the uneven surface with a pressure-sensitive adhesive layer facilitates improved heat resistance.

[0120] The acrylic resin film 20 may be formed of a single layer or multiple acrylic resin layers.

[0121] The acrylic resin film 20 may be unstretched and unoriented, or may be stretched. If stretching is not performed, the film thickness increases, which tends to result in a thick layer thickness for the polarizing plate, but on the other hand, the thick film thickness improves the handleability of the acrylic resin film. Such an acrylic resin film can be obtained from an unstretched film (raw film) obtained by forming an acrylic resin composition into a film. Conversely, if stretched, retardation is more likely to be exhibited, but stretching has the advantage of reducing the film thickness of the acrylic resin film and improving its rigidity. A stretched film can be produced by stretching an unstretched film using any method.

[0122] (2.5mm thick) The thickness of the (meth)acrylic resin film B(20) is not particularly limited, but may be 15 μm or more, 20 μm or more, or 30 μm or more, or 100 μm or less, 80 μm or less, 70 μm or less, or 65 μm or less.

[0123] (2.6 tensile modulus at 80°C) The tensile modulus (MPa) of the (meth)acrylic resin film B(20) at 80°C is not particularly limited, but may be 100 MPa or more, 200 MPa or more, 500 MPa or more, 3000 MPa or less, 2500 MPa or less, or 2000 MPa or less. The tensile modulus is in accordance with K7161-1:2014.

[0124] The tensile modulus of elasticity at 80°C of the (meth)acrylic resin film B(20) can be adjusted, for example, by the degree of polymerization and glass transition temperature of the (meth)acrylic resin, the blending ratio of the rubber elastomer particles, and the film-forming conditions of the (meth)acrylic resin film.

[0125] (2.7 Change in arithmetic mean roughness Ra before and after high-temperature test when rubber elastomer particles are included) When the (meth)acrylic resin film B (20) includes rubber elastomer particles, it is preferable that the change in arithmetic mean roughness Ra of the surface of the acrylic resin film B on the pressure-sensitive adhesive layer 10 side before and after exposing the (meth)acrylic resin film B alone to a temperature of 115°C for 24 hours is 5 nm or less. This further contributes to suppressing peeling at high temperatures. When manufactured by the extrusion molding method described below, the surface (smooth surface) on the side that comes into contact with the cooling roll has rubber elastomer particles pressed into it, so the change in surface roughness before and after the high-temperature test tends to exceed 5 nm. On the other hand, the surface (rough surface) on the side that comes into contact with the elastic roll in the extrusion molding method described below has fewer rubber elastomer particles pressed into it, so the change in surface roughness before and after the high-temperature test tends not to exceed 5 nm.

[0126] (Method for producing (meth)acrylic resin film 20) The acrylic resin can be formed into a film by any method, such as an extrusion molding method in which a molten resin is extruded into a film, or a solvent casting method in which a resin dissolved in an organic solvent is cast onto a flat plate and then the solvent is removed to form a film.

[0127] A specific example of the extrusion molding method is a method in which an acrylic resin composition is sandwiched between two rolls to form a film. In this case, by varying the rigidity of the roll surfaces, it is possible to make one side of the acrylic resin film 20 a smooth surface 20B and the other a rough surface 20A.

[0128] FIG. 3 is a schematic diagram illustrating an example of a method for producing an acrylic resin film 20 by extrusion molding. As shown in this figure, an acrylic resin composition heated to a molten state is extruded into a sheet from a die 11 and then compressed between a cooling roll 12 and an elastic roll 13 to form a sheet-like film and cool it. The cooling roll 12 is made of a highly rigid material such as metal, and the elastic roll 13 is made of an elastic material such as rubber that has a lower elastic modulus than the cooling roll 12. The elastic roll 13 can be a metal elastic roll or a rubber roll. Known metal elastic rolls can be used, such as those whose surface is made of a metal material and whose space between the metal surface and the shaft roll is filled with an elastic material such as a fluid or rubber. A rubber roll is a roll whose surface is made of an elastic material such as rubber.

[0129] When rubber elastomer particles are included, the sheet-like (meth)acrylic resin film 20 formed by the cooling roll 12 and elastic roll 13 has a smooth surface 20F on the surface that contacts the cooling roll 12 and a rough surface 20R on the surface that contacts the elastic roll 13. This is because the elastic roll 13 has a low radial elastic modulus and low indentation resistance, so even when in contact with the surface of the (meth)acrylic resin film 20, the rubber elastomer particles tend to protrude from the film surface against the pressing force of the surface of the elastic roll 13, which tends to cause unevenness on the film surface. Conversely, the surface of the cooling roll 12 has high surface rigidity, so the rubber elastomer particles protruding from the surface of the (meth)acrylic resin film 20 are easily pressed by the surface of the cooling roll 12 and sink into the film, which tends to make the film surface smooth.

[0130] The surface of the cooling roll 12 may be a mirror-finish roll, which can increase the surface smoothness of the smooth surface 20F. The cooling temperature of the cooling roll 12 is not particularly limited as long as it is a temperature at which the molten resin can be hardened to form a film, but is usually within the range of 10 to 100°C.

[0131] The surface roughness of the cooling roll 12 may be 0.2 S or less in terms of roughness expressed by a standard progression of maximum height. The surface roughness of the elastic roll 13 may be 0.2 S or less in terms of roughness expressed by a standard progression of maximum height.

[0132] The (meth)acrylic resin film B (20) formed into a sheet is wound into a roll on a winding roll 19. The raw (meth)acrylic resin film B (20) is unwound into a sheet as needed and used to manufacture optical components such as polarizing plates 100.

[0133] When the (meth)acrylic resin film B (20) is a laminate of a plurality of acrylic resin layers, a plurality of acrylic resin compositions may be extruded into a multilayer structure and then formed into a film.

[0134] The obtained (meth)acrylic resin film may be used as an unstretched film as it is, or may be stretched as needed by a known method such as uniaxial stretching or biaxial stretching to form a stretched film.

[0135] (3.1 Polarizer 30) In this embodiment, the polarizer is a uniaxially stretched polyvinyl alcohol-based resin film on which a dichroic pigment (iodine or a dichroic dye) is adsorbed and aligned, and which is crosslinked with a boron compound such as boric acid or borax.

[0136] The boron content in the polarizer may be 5.0% by mass or less, 4.2% by mass or less, and preferably 4.0% by mass or less, and may be 0.5% by mass or more, 1.0% by mass or more, and preferably 1.5% by mass or more.

[0137] The boron content (mass %) of the polarizer can be calculated from the amount of sodium hydroxide solution (1 mol / L) added dropwise to a measurement sample solution prepared by dissolving 0.2 g of the polarizer in 200 g of a 1.9 mass % mannitol aqueous solution until the measurement sample solution reaches the neutralization point.

[0138] Examples of polyvinyl alcohol resins constituting the polyvinyl alcohol resin film include saponified polyvinyl acetate resins, such as polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other monomers copolymerizable therewith.

[0139] Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

[0140] The degree of saponification of the polyvinyl alcohol resin is usually about 85 mol % or more, preferably about 90 mol % or more, and more preferably about 99 mol % or more.

[0141] The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc. modified with aldehydes may also be used.

[0142] The average degree of polymerization of the polyvinyl alcohol resin is preferably from 100 to 10,000, more preferably from 1,500 to 8,000, and even more preferably from 2,000 to 5,000. The average degree of polymerization of the polyvinyl alcohol resin can be determined in accordance with JIS K 6726 (1994). When the average degree of polymerization is within the above range, the polarizing performance and film processability tend to be excellent.

[0143] (3.2 Polarizer Manufacturing Method) A polarizer can be produced by a process of bringing a raw polyvinyl alcohol-based resin film (raw film) into contact with a treatment liquid (hereinafter also referred to as a "treatment process"). The method of bringing the film into contact with the treatment liquid may be a method of immersing the film in a treatment liquid (hereinafter also referred to as a "treatment bath") contained in a treatment tank, or a method of treating the film by applying the treatment liquid to the film surface by spraying, pouring, dropping, or the like. When the treatment process is performed by a method of immersing the film in a treatment bath, the number of treatment baths used in one treatment process is not limited to one, and one treatment process may be completed by sequentially immersing the film in two or more treatment baths.

[0144] Examples of the treatment liquid include a swelling liquid, a dyeing liquid, a crosslinking liquid, and a cleaning liquid. Examples of the treatment process include a swelling process in which a swelling liquid is brought into contact with the raw film to perform a swelling treatment, a dyeing process in which a dyeing liquid is brought into contact with the film after the swelling treatment to perform a dyeing treatment, a crosslinking process in which a crosslinking liquid is brought into contact with the film after the dyeing treatment to perform a crosslinking treatment, and a cleaning process in which a cleaning liquid is brought into contact with the film after the crosslinking treatment to perform a cleaning treatment. Between these series of treatment processes (i.e., before, after, and / or during any one or more treatment processes), a wet or dry uniaxial stretching treatment is performed. Other treatment processes may be added as necessary.

[0145] The swelling step is carried out for the purposes of removing foreign matter from the surface of the raw film, removing plasticizers in the raw film, imparting ease of dyeing, plasticizing the raw film, etc. As the swelling liquid, a medium containing water as the main component, such as water, distilled water, or pure water, is usually used.

[0146] The crosslinking process is a treatment performed for purposes such as water resistance and color adjustment through crosslinking. A solution in which a crosslinking agent is dissolved in a solvent can be used as the crosslinking liquid. Examples of crosslinking agents include boron compounds such as boric acid and borax. These may be used alone or in combination. The solvent can be, for example, water, but may also contain a water-compatible organic solvent. The concentration of the crosslinking agent in the crosslinking liquid, the temperature of the crosslinking bath, the immersion time of the film, and the number of crosslinking baths in which the film is immersed are not particularly limited. By appropriately selecting these, a polarized film with a boron content of 5.0% by mass or less can be obtained. When the dichroic dye used in the dyeing process is iodine, the crosslinking liquid preferably contains an iodide in addition to boric acid. The amount of iodide can be, for example, 1 to 30 parts by mass per 100 parts by mass of water. Examples of iodides include potassium iodide and zinc iodide. In addition, compounds other than iodides, such as zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, and sodium sulfate, may also be present. The crosslinking treatment may be carried out multiple times, usually 2 to 5 times. In this case, the composition and temperature of each crosslinking bath used may be the same or different.

[0147] The cleaning step is carried out for the purpose of removing excess chemicals such as boric acid and iodine adhering to the polyvinyl alcohol-based resin film. The cleaning step is carried out, for example, by immersing the crosslinked polyvinyl alcohol-based resin film in a cleaning bath containing a cleaning solution. Note that the cleaning step can also be carried out by spraying the cleaning solution onto the film as a shower instead of immersing the film in the cleaning bath, or by combining immersion in the cleaning bath with spraying the cleaning solution. The boron content of the final polarizer can be adjusted by adjusting the cleaning treatment conditions (e.g., the time of contact with the cleaning solution and the temperature of the cleaning solution).

[0148] As described above, the raw film is subjected to a wet or dry uniaxial stretching treatment during the series of treatment steps (i.e., before, after, and / or during any one or more treatment steps). The uniaxial stretching step can be performed multiple times until a polarizer is obtained from the raw film.

[0149] The thickness of the polarizer is usually 65 μm or less, preferably 50 μm or less, more preferably 35 μm or less, and even more preferably 30 μm or less. The thickness of the polarizer is usually 2 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. The thickness of the polarizer can be controlled, for example, by selecting a polyvinyl alcohol-based resin film, adjusting the stretching ratio, etc. With regard to the tensile modulus of the polarizer at 25° C., the tensile modulus in the MD direction may be 12,000 MPa to 25,000 MPa, and the tensile modulus in the TD direction may be 3,500 MPa to 7,000 MPa.

[0150] (4.1 Thermoplastic resin film A(40)) The thermoplastic resin film A (40) is preferably a polyester resin film or a (meth)acrylic resin film.

[0151] (4.2 Polyester resin film) Examples of polyester resins include polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate.

[0152] (4.3 (Meth)acrylic resin film) The (meth)acrylic resin film in the thermoplastic resin film A contains a (meth)acrylic resin.

[0153] The (meth)acrylic resin film in the thermoplastic resin film A is the same as that described for the (meth)acrylic resin film B above.

[0154] (4.3 Thickness) The thickness of the thermoplastic resin film A (20) is not particularly limited, but may be 10 μm or more, 20 μm or more, 30 μm or more, 100 μm or less, 90 μm or less, or 80 μm or less.

[0155] (4.4 Tensile modulus at 80°C) The tensile modulus (MPa) of the thermoplastic resin film A (20) at 80°C is not particularly limited, but may be 100 MPa or more, 200 MPa or more, 500 MPa or more, 3000 MPa or less, 2500 MPa or less, or 2000 MPa or less.

[0156] The tensile modulus at 80°C of the thermoplastic resin film A can be adjusted in the case of a (meth)acrylic resin film by the degree of polymerization and glass transition temperature of the (meth)acrylic resin, the blending ratio of rubber elastomer particles, the film formation conditions of the (meth)acrylic resin film, etc. In addition, in the case of a polyester resin film, it can be adjusted by the degree of polymerization and glass transition temperature of the polyester resin, the production conditions of the polyester resin film, etc.

[0157] (Adhesive layer 52, 54) An adhesive layer 52 may be present between the thermoplastic resin film A (40) and the polarizer 30. An adhesive layer 54 may be present between the (meth)acrylic resin film B (20) and the polarizer 30.

[0158] Examples of adhesive compositions that form the adhesive layer 52 and the adhesive layer 54 include water-based adhesives and active energy ray-curable adhesives. The adhesive compositions that form the adhesive layer 52 and the adhesive layer 54 may be the same or different.

[0159] The adhesive composition is preferably an active energy ray-curable adhesive.

[0160] Examples of aqueous adhesives include conventionally known adhesive compositions that use a polyvinyl alcohol resin or a urethane resin as a main component. Active energy ray-curable adhesives are adhesives that are cured by irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays. When an active energy ray-curable adhesive is used, the adhesive layer is a cured product layer of the adhesive.

[0161] The active energy ray-curable adhesive may be an adhesive containing an epoxy compound that cures by cationic polymerization as a curable component, and is preferably an ultraviolet-curable adhesive containing such an epoxy compound as a curable component. The epoxy compound refers to a compound having an average of one or more, preferably two or more, epoxy groups in the molecule. Only one type of epoxy compound may be used, or two or more types may be used in combination.

[0162] Examples of epoxy compounds include hydrogenated epoxy compounds (glycidyl ethers of polyols having alicyclic rings) obtained by reacting epichlorohydrin with an alicyclic polyol obtained by hydrogenating the aromatic rings of an aromatic polyol; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts; and alicyclic epoxy compounds, which are epoxy compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule.

[0163] The active energy ray-curable adhesive may contain a radically polymerizable (meth)acrylic compound as a curable component, instead of or in addition to the epoxy compound. Examples of the (meth)acrylic compound include (meth)acryloyloxy group-containing compounds such as (meth)acrylate monomers having one or more (meth)acryloyloxy groups in the molecule, and (meth)acrylate oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyloxy groups in the molecule.

[0164] When the active energy ray-curable adhesive contains an epoxy compound that cures by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes.

[0165] When the active energy ray-curable adhesive contains a radically polymerizable component such as a (meth)acrylic compound, it preferably contains a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

[0166] The adhesion between the polarizer 30 and the thermoplastic resin film can include a process of applying an adhesive composition to the bonding surface of the polarizer 30 and / or the bonding surface of the thermoplastic resin film, or injecting the adhesive composition between the polarizer 30 and the thermoplastic resin film, overlapping the two films with a layer of the adhesive composition between them, and pressing them together from above and below using, for example, a laminating roll.

[0167] The adhesive composition layer can be formed by various coating methods, such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, etc. Alternatively, the adhesive composition may be cast between the polarizer 30 and the thermoplastic resin film while they are continuously fed so that the bonding surfaces of the two face inward.

[0168] Before applying the adhesive composition, one or both of the bonding surfaces of at least one of the polarizer 30, the thermoplastic resin film A (40), and the (meth)acrylic resin film B (20) may be subjected to an adhesion-improving treatment (surface activation treatment) such as saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, or anchor coating treatment.

[0169] When an active energy ray-curable adhesive is used, the adhesive composition layer is cured by irradiating it with active energy rays. The light source used to irradiate the active energy rays may be any light source capable of generating ultraviolet rays, electron beams, X-rays, etc. In particular, light sources having an emission distribution of wavelengths of 400 nm or less, such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps, are preferably used.

[0170] The thickness of each of the adhesive layers 52 and 54 is, for example, from 0.1 μm to 100 μm, preferably from 0.5 μm to 80 μm, more preferably from 1 μm to 60 μm, and even more preferably from 2 μm to 50 μm. From the viewpoint of thinning the polarizing plate, the thickness of the adhesive layer is preferably 30 μm or less, or 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. When a water-based adhesive is used, the thickness of the adhesive layer may be smaller than the above.

[0171] The adhesive layer 52 and the adhesive layer 54 may have the same thickness or different thicknesses.

[0172] The tensile modulus of elasticity at 80° C. of the adhesive layers 52, 54 is not limited, but may be 10 to 500 MPa, preferably 15 to 300 MPa, more preferably 20 to 200 MPa, and even more preferably 30 to 150 MPa.

[0173] (5) Characteristics of Polarizing Laminates (5.1 Curl direction of polarizing laminate at high temperatures) In this embodiment, when the polarizing laminate 90 is exposed to an environment at 80°C for two hours, it curls (reverse curl) so that the surface on the thermoplastic resin film A (40) side becomes convex and the surface on the (meth)acrylic resin film B (20) side becomes concave, as shown in (a) of Figure 4, or it does not curl at all.

[0174] Here, as shown in (a) of Figure 4, the case where the polarizing laminate 90 curls so that the surface on the thermoplastic resin film A (40) side is convex and the surface of the (meth)acrylic resin film B (20) is concave is called reverse curl. As shown in (b) of Figure 4, the case where the polarizing laminate 90 curls so that the surface on the thermoplastic resin film A (40) side is concave and the surface of the (meth)acrylic resin film B (20) is convex is called normal curl.

[0175] The polarizing laminate 90 can be made to "reverse curl" or "not curl" by adjusting the configuration of the polarizing laminate 90. For example, the polarizing laminate 90 can be configured such that the thermoplastic resin film A (40) is different from the (meth)acrylic resin film B (20), the thickness of the thermoplastic resin film A (40) is different from the thickness of the (meth)acrylic resin film B (20), or the adhesive layer 52 and the adhesive layer 54 are formed from different adhesive compositions, thereby making the layer configuration of the polarizing laminate 90 asymmetric with respect to the polarizer. The polarizing laminate 90 is preferably configured such that STA is greater than STB in (5.4 Relationship between Films) described below, and more preferably such that STA - STB ≥ 18,380 MPa μm.

[0176] (5.2 Curling force of polarizing laminate at high temperatures) The maximum curl force of polarizing laminate 90 during exposure to an environment at 80° C. for 2 hours is 3 N or less.

[0177] Here, the curling force is defined as follows. As shown in Figure 5(a), a circular sample S of a polarizing laminate with a diameter of 22 mm was placed on the horizontal surface of a plate P1 with the (meth)acrylic resin film B (20) side facing up. A jig P2 with a flat bottom was fixed so that it covered the top surface of the sample S and the distance between the plate P1 and the jig P2 was such that the upward force applied to the jig P2 was the distance determined by the zero-gap setting at room temperature + 0.02 mm. Next, while monitoring the force applied to the jig P2, the plate P1 was heated from 23°C to 80°C at 2°C / min, held at 80°C for 120 minutes, and then cooled to 23°C at 2°C / min and held there for 120 minutes. Exposure to a high temperature environment caused the polarizer in the sample S to shrink in the absorption axis direction, causing the polarizing laminate to curl, applying an upward force to the jig P as shown in Figure 5(b). Note that a force corresponding to the degree of curl, whether forward or reverse, was applied to the jig P2. The maximum upward force applied to the jig P2 recorded at this time is taken as the curling force "N."

[0178] A large curling force means that the polarizing laminate is prone to curling when exposed to high temperatures.

[0179] (5.3 Shrinkage in the TD direction of polarizing laminate before and after exposure to high temperatures) The polarizing laminate 90 has a dimensional shrinkage rate in the TD direction (transmission axis) of 1.25% or less before and after being exposed to an environment at 80° C. (relative humidity 5%) for 144 hours. The size of the sample for measuring the shrinkage rate can be, for example, 100 x 100 mm. The TD shrinkage rate (%) is defined as follows: Shrinkage rate in TD direction (transmission axis direction) (80℃) = [(L0-L80) / L0] x 100 In the above formula, L0 is the TD length at room temperature (25°C) and relative humidity 55%, and L80 is the TD length when exposed to an 80°C environment (relative humidity 5%) for 144 hours and then returned to room temperature (25°C) and relative humidity 55%.

[0180] The MD direction of the polarizing laminate means the absorption axis direction of the polarizer of the polarizing laminate, and the TD direction of the polarizing laminate means the transmission axis direction of the polarizer of the polarizing laminate. The shrinkage percentage in the TD direction of the polarizing laminate before and after exposure to high temperatures can be within the above range by adjusting the type of thermoplastic resin film A (40) in the polarizing laminate, the tensile modulus at 80°C of the thermoplastic resin film A (40) or the (meth)acrylic resin film B (20), the glass transition temperature of the thermoplastic resin film A (40) or the (meth)acrylic resin film B (20), the polarizer, etc. Furthermore, if the shrinkage percentage in the TD direction of the polarizing laminate before and after exposure to high temperatures is low, the polarizing laminate 90 is more likely to "reverse curl" or "not curl."

[0181] (5.4 Relationships between films) In the polarizing laminate according to this embodiment, STA is defined as the tensile modulus (MPa) at 80°C of thermoplastic resin film A multiplied by the film thickness (μm), When STB is the product of the tensile modulus (MPa) of the (meth)acrylic resin film B at 80° C. and the film thickness (μm), the following formula may be satisfied. STA-STB≧18,380MPa·μm

[0182] (Action and effect) In this embodiment, the curl direction and curl force of the polarizing laminate 90 when exposed to a high-temperature environment are specified, and further, the dimensional shrinkage rate of the polarizing laminate 90 when exposed to a high-temperature environment is specified.

[0183] When such a polarizing plate 100 is attached to a glass substrate such as a liquid crystal cell and exposed to a high temperature such as 80°C for a long period of time, peeling of the adhesive layer 10 in the polarizing plate 100 is suppressed at the outer periphery, particularly at both ends in the absorption axis direction.

[0184] The reason for this is not clear, but it is thought that the polarizing laminate has a low shrinkage rate at high temperatures, the polarizing laminate has low curl strength at high temperatures, and the polarizing laminate curls in the reverse direction at high temperatures, which, combined with each other, makes it difficult for air bubbles to become trapped between the polarizing laminate and the adhesive at both ends in the absorption axis direction of the polarizing plate.

[0185] In addition, in the polarizing plate 100 according to the present embodiment, it is considered that the peel-suppressing effect is also achieved when the following formula is satisfied: (I) on the surface 20A of the (meth)acrylic resin film B on the pressure-sensitive adhesive layer 10 side, some rubber elastomer particles 20b protrude from the surface 20Ab of the (meth)acrylic resin phase and the arithmetic mean roughness Ra is 8 nm or more; and (II) when the tensile modulus (MPa) × film thickness (μm) of the thermoplastic resin film A at 80°C is defined as STA and the tensile modulus (MPa) × film thickness (μm) of the (meth)acrylic resin film B at 80°C is defined as STB. STA-STB≧18,380MPa·μm

[0186] When the structure (I) is employed, it is believed that the adhesion between the pressure-sensitive adhesive layer 10 and the surface 20A of the (meth)acrylic resin film B is improved.

[0187] When it has the configuration (II), this means that the rigidity of the thermoplastic resin film A at high temperatures is sufficiently higher than the rigidity of the (meth)acrylic resin film B at high temperatures. It is believed that this allows the rigidity of the thermoplastic resin film A to prevent the outer periphery of the (meth)acrylic resin film B from lifting up. [Example]

[0188] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, % representing the content or amount used is based on mass unless otherwise specified.

[0189] The tensile modulus of elasticity at 80° C. of various films, the arithmetic mean roughness Ra of the film, the storage modulus of the adhesive, and the durability of the polarizing plate were evaluated by the methods described below.

[0190] (Measurement of tensile modulus) The resin film was cut into a rectangle measuring 70 mm in length and 10 mm in width. The length direction of the test piece was the MD direction of the resin film, and the width direction was the TD direction (the direction perpendicular to the MD direction) of the resin film. Next, the test piece was clamped at both ends in the length direction (MD direction of the resin film) with the upper and lower grippers of a tensile tester (Autograph AG-1S tester, manufactured by Shimadzu Corporation) so that the distance between the grippers was 5 cm, and the test piece was pulled in the length direction (MD direction of the resin film) at a tension rate of 50 mm / min in an environment of 80 ° C. The tensile modulus (MPa) of the resin film in the MD direction at 80 ° C. was calculated from the slope of the initial straight line in the obtained stress-strain curve.

[0191] (Measurement of the arithmetic mean roughness Ra of the film) The arithmetic mean roughness Ra within the film surface was measured for each type of film using a non-contact surface / layer cross-sectional shape measurement system (product name "vertscan") manufactured by Ryoka Systems Co., Ltd. These measurements were taken over a 100 mm wide area centered on the center of the width direction of each type of film, and the values ​​were calculated from measurements taken at any point within that 100 mm wide area using a 50x objective lens over a measurement range of 70 μm x 100 μm.

[0192] (Measurement of curling force of polarizing laminate) The maximum curl force of the polarizing laminate at 80° C. was measured according to the following procedure. A circular sample with a diameter of 22 mm was cut from the polarizing laminate. The circular polarizing laminate was placed on the main plate of a viscoelasticity measuring device (Anton Paar's "Physica MCR301") with the acrylic resin film (B) side facing up (the side facing the measuring jig), and a measuring jig (PP25) was placed so that its flat bottom surface covered the entire top surface of the polarizing laminate. The gap between the measuring jig and the plate was adjusted so that the force applied to the measuring jig was the distance specified by the zero gap setting at room temperature, and the measuring jig was raised 0.02 mm from this point to a reference height, at which point the measuring jig was fixed.

[0193] Next, while monitoring the force acting on the measuring jig, the temperature of the main plate was raised from 23°C to 80°C at 2°C / min, held at 80°C for 120 minutes, and then lowered to 23°C at 2°C / min and held there for 120 minutes. The maximum upward force acting on the measuring jig due to the sample's thermal contraction recorded during this process was taken as the curl force [N] at 80°C.

[0194] After the temperature increase program was completed (after maintaining the temperature at 23° C. for 120 minutes), the direction of curl of the polarizing laminate was visually determined.

[0195] (Measurement of shrinkage rate in the TD direction (transmission axis direction) of polarizing laminate) The shrinkage rate in the TD direction of the polarizing laminate was measured by the following method. First, a long polarizing laminate was cut into a square measuring 100 mm in the longitudinal direction (MD) × 100 mm in the transverse direction (TD). The MD direction of the polarizing laminate refers to the absorption axis direction of the polarizer in the polarizing laminate, and the TD direction of the polarizing laminate refers to the transmission axis direction of the polarizer in the polarizing laminate. After cutting the plate, the dimension in the TD direction (L0) was measured using a two-dimensional measuring instrument NEXIVVMR-12072 (manufactured by Nikon Corporation). The dimension in the MD direction was also measured in the same manner.

[0196] Next, the polarizing laminate was left to stand for 144 hours in an environment at 80°C (relative humidity: 5%). After this step, the dimensions in the TD direction (L80) and MD direction of the polarizing laminate were measured in the same manner as above.

[0197] The shrinkage rate in the TD direction (%) was calculated from the following formula, and the shrinkage rate in the TD direction (80° C.) in the width direction of each polarizing plate was calculated. Shrinkage rate in TD direction (transmission axis direction) (80℃) = [(L0-L80) / L0] x 100

[0198] If the polarizing laminate curled after being left standing in an environment at 80°C for 144 hours, the polarizing laminate was sandwiched between glass plates to make the polarizing laminate flat, and then the measurement was performed.

[0199] (Measurement of storage modulus) The storage modulus of the pressure-sensitive adhesive layer at a temperature of 25°C or 60°C was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). The pressure-sensitive adhesive layer was removed from the pressure-sensitive adhesive sheet, multiple layers were stacked to a thickness of 1 mm, and cut into a piece with a diameter of 8 mm. The stage / pressure-sensitive adhesive layer / measuring system was set in the device so that they were stacked in this order, and measurements were carried out in this state in the temperature range of -20°C to 80°C under conditions of a frequency of 1.0 Hz, a deformation of 1%, a load of 1 N, and a heating rate of 10°C / min, to determine the storage modulus of the pressure-sensitive adhesive layer at a temperature of 25°C or 60°C.

[0200] (Durability evaluation of polarizing plates) The polarizing plate was cut into 160mm x 220mm pieces (with the long sides parallel to the absorption axis of the polarizing plate), and the adhesive layer side of the cut polarizing plate was attached to Eagle glass. The polarizing plate attached to the glass was then subjected to a test in which it was kept in an oven maintained at 80°C for 500 hours under dry conditions. After the test, the polarizing plate was checked for peeling between the adhesive layer and the film at the edge (short side) of the polarizing plate. The area where the distance from the edge of the adhesive layer corresponding to the edge of the short side of the polarizing plate to the tip of the peeling in the long side direction was 1mm or more was extracted, and the sum of the short side lengths of the area was calculated. The ratio of this sum to the short side length was calculated and evaluated according to the following criteria. ○: The area where peeling has occurred over a distance of 1 mm or more is less than 20% of the length of the short side ×: The area where peeling has occurred over a distance of 1 mm or more is 20% or more of the length of the short side.

[0201] Preparation of various films to be used (Preparation of Thermoplastic Resin Film A) (Thermoplastic resin film A-1) A uniaxially stretched polyethylene terephthalate film having a thickness of 80 μm and a tensile modulus (MD direction) of 1,573 MPa at 80° C. was prepared.

[0202] (Thermoplastic resin film A-2) A (meth)acrylic resin film having a thickness of 80 μm and a tensile modulus (MD direction) at 80° C. of 1,378 MPa was prepared by the following procedure. The following raw materials were prepared. (Meth)acrylic resin (A): A methacrylic resin (a homopolymer of methyl methacrylate) with a triad syndiotacticity (rr) of 76%. (Meth)acrylic resin (B-2): a radical copolymer of methyl methacrylate / methyl acrylate = 98.6 / 1.4 (mass ratio) and a triad syndiotacticity (rr) of 51% Rubber elastomer particles (C): These elastomer particles have a three-layer structure: the innermost layer is made of a hard polymer polymerized with methyl methacrylate and a small amount of allyl methacrylate, the middle layer is made of a soft elastomer polymerized with butyl acrylate as the main component and styrene and a small amount of allyl methacrylate, and the outermost layer is made of a hard polymer polymerized with methyl methacrylate and a small amount of ethyl acrylate. The average particle size up to the middle layer is 240 nm. In this rubber particle, the combined mass of the innermost and middle layers is 70% of the entire particle. An unstretched (meth)acrylic resin film having a thickness of 80 μm was produced by melt extrusion from a mixture of 12 parts of (meth)acrylic resin (A), 68 parts of (meth)acrylic resin (B-2), and 20 parts of rubber elastomer particles (C).

[0203] (Thermoplastic resin film A-3) A (meth)acrylic resin film having a thickness of 80 μm and a tensile modulus (MD direction) at 80° C. of 1,000 MPa was prepared by the following procedure. The following raw materials were prepared. (Meth)acrylic resin (B-1): a radical copolymer of methyl methacrylate / methyl acrylate = 97 / 3 (mass ratio) with a triad syndiotacticity (rr) of 48% An unstretched (meth)acrylic resin film having a thickness of 80 μm was produced by melt extrusion from a mixture of 70 parts of (meth)acrylic resin (B-1) and 30 parts of rubber elastomer particles (C). The (meth)acrylic resin (A) and rubber elastomer particles (C) were the same as those used in the thermoplastic resin film A-2.

[0204] (Thermoplastic resin film A-4) A (meth)acrylic resin film having a thickness of 60 μm and a tensile modulus (MD direction) at 80° C. of 1279 MPa was prepared by the following procedure. A 60 μm-thick unstretched (meth)acrylic resin film was produced by melt extrusion from a mixture of 16 parts (meth)acrylic resin (A), 64 parts (meth)acrylic resin (B-1), and 20 parts rubber elastomer particles (C). The same (meth)acrylic resin (A) and rubber elastomer particles (C) as used in thermoplastic resin film A-2 were used, and the same (meth)acrylic resin (B-1) as used in thermoplastic resin film A-3 was used.

[0205] (Thermoplastic resin film A-5) A (meth)acrylic resin film having a thickness of 80 μm and a tensile modulus at 80° C. of 1431 MPa was prepared by the following procedure. An unstretched (meth)acrylic resin film having a thickness of 80 μm was produced by melt extrusion from a mixture of 50 parts of (meth)acrylic resin (A), 30 parts of (meth)acrylic resin (B-1), and 20 parts of rubber elastomer particles (C). The (meth)acrylic resin (A) and rubber elastomer particles (C) were the same as those used in thermoplastic resin film A-2, and the (meth)acrylic resin (B-1) was the same as that used in thermoplastic resin film A-3.

[0206] (Thermoplastic resin film A-6) A (meth)acrylic resin film having a thickness of 60 μm and a tensile modulus of elasticity of 1078 MPa at 80° C. was prepared. A 60 μm-thick unstretched (meth)acrylic resin film was produced by melt extrusion from a mixture of 50 parts (meth)acrylic resin (A), 30 parts (meth)acrylic resin (B-1), and 20 parts rubber elastomer particles (C). The same (meth)acrylic resin (A) and rubber elastomer particles (C) were used as the thermoplastic resin film A-2, and the same (meth)acrylic resin (B-1) as the thermoplastic resin film A-3.

[0207] (Preparation of acrylic resin film B) ((Meth)acrylic resin film B-1) The acrylic resin used was a copolymer of methyl methacrylate / methyl acrylate in a mass ratio of 96 / 4.The rubber elastomer particles used were the rubber elastomer particles (C) described above.

[0208] Pellets containing the acrylic resin and the rubber elastomer particles (C) in a mass ratio of 70 / 30 were melt-kneaded in a twin-screw extruder to produce pellets of an acrylic resin composition. The pellets were fed into a 65 mmφ single-screw extruder and extruded through a T-die set at 275°C. The extruded film-like molten resin was sandwiched between a polishing roll (cooling roll) with a mirror surface set at 45°C and a metal elastic roll (elastic roll) with a high elastic modulus and a metal surface formed of a metal material and filled with a fluid, and cooled to produce an acrylic resin film B-1 with a thickness of 60 μm and a tensile modulus of 1027 MPa at 80°C.

[0209] The arithmetic mean roughness Ra of the contact surface (smooth surface) with the polishing roll and the contact surface (uneven surface) with the elastic metal roll (elastic roll) of the obtained acrylic resin film B-1 was measured by the method described above. The Ra of the smooth surface was 2.0 nm, and the Ra of the uneven surface was 12.9 nm. Furthermore, after the film was dried at 115°C for 24 hours, the arithmetic mean roughness Ra of the contact surface (smooth surface) with the polishing roll and the contact surface (uneven surface) with the elastic metal roll (elastic roll) was measured by the same method and the amount of change was calculated. The Ra of the uneven surface was 2.6 nm, and the Ra of the smooth surface was 13.6 nm.

[0210] ((Meth)acrylic resin film B-2) A 60 μm-thick unstretched (meth)acrylic resin film was produced by melt extrusion from a mixture of 85 parts (meth)acrylic resin (B-1) and 15 parts rubber elastomer particles (C). The same (meth)acrylic resin (A) and rubber elastomer particles (C) as those used in thermoplastic resin film A-2 were used, and the same (meth)acrylic resin (B-1) as that used in thermoplastic resin film A-3 was used.

[0211] ((Meth)acrylic resin film B-3) A 50 μm-thick unstretched (meth)acrylic resin film was produced by melt extrusion from a mixture of 70 parts of (meth)acrylic resin (B-1) and 30 parts of rubber elastomer particles (C). The rubber elastomer particles (C) were the same as those used in the thermoplastic resin film A-2, and the (meth)acrylic resin (B-1) was the same as those used in the thermoplastic resin film A-3.

[0212] ((Meth)acrylic resin film B-4) An unstretched (meth)acrylic resin film having a thickness of 80 μm was produced by melt extrusion from a mixture of 85 parts of (meth)acrylic resin (B-1) and 15 parts of rubber elastomer particles (C). The rubber elastomer particles (C) were the same as those used in the thermoplastic resin film A-2, and the (meth)acrylic resin (B-1) was the same as those used in the thermoplastic resin film A-3.

[0213] (Photo-curing adhesive A) The following raw materials were prepared: (a1) 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (a2) Neopentyl glycol diglycidyl ether (a3) A polymer with a weight average molecular weight of 15,000 obtained by radical polymerization of a monomer consisting of 25 parts of glycidyl methacrylate and 75 parts of methyl methacrylate (GMA-PMMA (polymethyl methacrylate) copolymer) (a4) Hydroxybutyl vinyl ether (b1) Triarylsulfonium hexafluorophosphate 25 parts by mass of (a1), 55 parts by mass of (a2), 15 parts by mass of (a3), 5 parts by mass of (a4), and 2.25 parts by mass (solid content) of (b1) were mixed and then degassed to prepare photocurable adhesive A. Note that photocationic polymerization initiator (b1) was actually mixed as a 50% propylene carbonate solution. The cured layer of photocurable adhesive A had a tensile modulus of elasticity of 47 MPa at 80°C.

[0214] (Photo-curing adhesive B) The following raw materials were prepared: (a5) 2-ethylhexyl glycidyl ether 70 parts by mass of (a1), 20 parts by mass of (a2), 10 parts by mass of (a5), and 2.25 parts by mass (solid content) of (b1) were mixed and then degassed to prepare photocurable adhesive B. Note that (a1), (a2), and (b1) were the same as those used in photocurable adhesive A. The tensile modulus of elasticity of the cured layer of photocurable adhesive B at 80°C was 139 MPa.

[0215] In the protective films used in the examples and comparative examples, the width direction is parallel to the transmission axis direction of the polarizer.

[0216] (Preparation of adhesive layer) (Preparation of (meth)acrylic resin α-1, which serves as the base for the adhesive) A reaction vessel equipped with a condenser, nitrogen inlet, thermometer, and stirrer was charged with 80 parts by weight of n-butyl acrylate, 10 parts by weight of methyl acrylate, 8.0 parts by weight of 2-phenoxyethyl acrylate, 1.0 part by weight of 2-hydroxyethyl acrylate, and 1.0 part by weight of acrylic acid as acrylic monomers. Ethyl acetate was then added in an amount of 150 parts per 100 parts of the total acrylic monomers to prepare an ethyl acetate solution of the acrylic monomers. The air in the reaction vessel was purged with nitrogen gas to remove oxygen, and the internal temperature was raised to 55°C. A solution of azobisisobutyronitrile (polymerization initiator) dissolved in ethyl acetate was then added in an amount of 0.3 parts by weight per 100 parts of the total monomers. After adding the polymerization initiator, the temperature was maintained for 1 hour. Then, ethyl acetate was continuously added to the reaction vessel while maintaining the internal temperature at 54 to 56°C. When the concentration of the (meth)acrylic resin α-1 reached 35% by mass, the addition of ethyl acetate was stopped. The temperature was maintained for 12 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin α-1 to 20% by mass, thereby preparing an ethyl acetate solution of the (meth)acrylic resin α-1.

[0217] (Preparation of adhesive layer α-1) For 100 parts of the solid content of the obtained (meth)acrylic resin α-1 for pressure-sensitive adhesives, 0.3 parts by mass (active ingredient basis) of a crosslinking agent, trade name "D-103" manufactured by Mitsui Chemicals, Inc. (an ethyl acetate solution (solid content concentration 75% by mass) of a trimethylolpropane adduct of tolylene diisocyanate), 1.0 part by mass of a silane compound, trade name "KR-519" manufactured by Shin-Etsu Chemical Co., Ltd. (a mercapto group-containing silicone oligomer, mercapto equivalent 450 g / mol), and N-octyl-4-methylpyridinium nitrite were used as an ionic compound. 2.5 parts by mass of hexafluorophosphate was added, and ethyl acetate was further added so that the solids concentration became 14% by mass to prepare a solution of PSA composition A. PSA composition α-1 was applied to the release-treated surface of a release-treated polyethylene terephthalate separate film ("PLR-382190" obtained from Lintec Corporation) using an applicator so that the thickness after drying would be 20 μm, and the applied film was dried at 100° C. for 1 minute to prepare PSA layer α-1 (adhesive sheet). The storage modulus at 25°C was 0.107 MPa, and the storage modulus at 60°C was 0.076 MPa.

[0218] [Example 1] (Preparation of polarizing laminate and durability evaluation) The side of (meth)acrylic resin film B-1 that contacts the polishing roll (the mirror surface side) was subjected to corona treatment, and then a photocurable adhesive A containing a photocurable epoxy resin and a photocationic polymerization initiator was applied to the corona-treated surface to a thickness of 3 μm. On the other hand, one side of the thermoplastic resin film A-1 (PET) serving as the thermoplastic resin film A was subjected to a corona treatment, and then the photocurable adhesive B was coated to a thickness of 3 μm on the corona-treated surface.

[0219] Next, the adhesive-coated side of the acrylic resin film B-1 was placed on one side of a 24-μm-thick polarizing film in which iodine was adsorbed and oriented in polyvinyl alcohol, and the adhesive-coated side of the thermoplastic resin film A-1 (PET) was placed on the other side of the polarizing film, and they were sandwiched and pressed between a pair of 100 mmφ nip rolls. After that, ultraviolet light was irradiated from the acrylic resin film B-1 side to cure both adhesive layers, thereby producing a polarizing laminate. The curling force of the obtained polarizing laminate was measured to be 2.5 N, the curl direction was reverse curl, and the dimensional shrinkage rate in the TD (transmission axis) direction was 0.54%. The polarizing film used had a tensile modulus of elasticity of 14,445 MPa in the MD direction and 4,324 MPa in the TD direction at 25°C.

[0220] (Preparation of polarizing plate) The outer surface of the acrylic resin film B-1 of the polarizing laminate was bonded to the side of the adhesive layer α-1 prepared above opposite to the separate film (the adhesive layer side) using a laminator, and then the laminate was cured for 5 days at a temperature of 23°C and a relative humidity of 65%RH to obtain a polarizing plate.

[0221] The resulting polarizing plate was subjected to a durability evaluation using the method described above. When the plate was held at 80°C for 500 hours under dry conditions, peeling occurred in an area of ​​0.23% of the length of the short side.

[0222] [Example 2] A polarizing laminate was produced in the same manner as in Example 1, except that thermoplastic resin film A-5 was used instead of thermoplastic resin film A-1 (PET) as thermoplastic resin film A, and photocurable adhesive A was used for both adhesive layers, and a durability evaluation was performed. The polarizing laminate had a reverse curl, a curl force of 0.74 N, and a dimensional shrinkage rate in the TD direction of 1.03%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in an area covering 1.0% of the length of the short side.

[0223] [Example 3] A polarizing laminate was produced in the same manner as in Example 1, except that thermoplastic resin film A-2 was used instead of thermoplastic resin film A-1 (PET) as thermoplastic resin film A, and photocurable adhesive A was used for both adhesive layers, and a durability evaluation was performed. The polarizing laminate had a reverse curl, a curl force of 0.37 N, and a dimensional shrinkage rate in the TD direction of 1.07%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in an area covering 1.6% of the length of the short side.

[0224] [Example 4] A polarizing laminate was produced in the same manner as in Example 1, except that thermoplastic resin film A-3 was used instead of thermoplastic resin film A-1 (PET) as thermoplastic resin film A, and photocurable adhesive A was used for both adhesive layers, and a durability evaluation was performed. The polarizing laminate had a reverse curl, a curl force of 0.09 N, and a dimensional shrinkage rate in the TD direction of 1.23%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in an area covering 2.9% of the length of the short side.

[0225] [Comparative Example 1] A polarizing laminate was produced in the same manner as in Example 1, except that thermoplastic resin film A-4 was used instead of thermoplastic resin film A-1 (PET) as thermoplastic resin film A, and photocurable adhesive A was used for both adhesive layers, and a durability evaluation was performed. The polarizing laminate had a normal curl, a curl force of 0.04 N, and a dimensional shrinkage rate in the TD direction of 1.30%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in an area covering 52.7% of the length of the short side.

[0226] Comparative Example 2 A polarizing laminate was produced in the same manner as in Comparative Example 1, except that the surface of (meth)acrylic resin film B-1 attached to the polyvinyl alcohol film was reversed, and a durability evaluation was performed. The polarizing laminate had a normal curl, a curl force of 0.04 N, and a dimensional shrinkage rate in the TD direction of 1.30%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under dry conditions, peeling occurred in an area of ​​72.5% of the length of the short side.

[0227] Comparative Example 3 A polarizing laminate was produced in the same manner as in Example 4, except that (meth)acrylic resin film B-2 was used as (meth)acrylic resin film B, and a durability evaluation was performed. The polarizing laminate had a normal curl, a curl force of 0.075 N, and a dimensional shrinkage rate in the TD direction of 1.09%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in the entire region along the length of the short side.

[0228] Comparative Example 4 A polarizing laminate was produced in the same manner as in Comparative Example 1, except that thermoplastic resin film A-6 was used instead of thermoplastic resin film A-4 as thermoplastic resin film A, and (meth)acrylic resin film B-3 was used as (meth)acrylic resin film B, and a durability evaluation was performed. The polarizing laminate had a reverse curl, a curl force of 0.035 N, and a dimensional shrinkage rate in the TD direction of 1.60%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in the entire region along the length of the short side.

[0229] Comparative Example 5 A polarizing laminate was produced in the same manner as in Comparative Example 4, except that (meth)acrylic resin film B-4 was used as acrylic resin film B, and a durability evaluation was performed. The polarizing laminate had a normal curl, a curl force of 0.29 N, and a dimensional shrinkage rate in the TD direction of 1.10%. In addition, in a test in which the laminate was kept at 80°C for 500 hours under drying conditions, peeling occurred in the entire region along the length of the short side.

[0230] [Table 1] [Table 2] [Explanation of symbols]

[0231] 10...adhesive layer, 20...(meth)acrylic resin film B, 20b...rubber elastomer particles, 20A...surface of (meth)acrylic resin film B on the adhesive layer side, 30...polarizer, 40...thermoplastic resin film A, 52, 54...adhesive layer, 100...polarizing plate.

Claims

1. A polarizing plate comprising: a polarizing laminate comprising a thermoplastic resin film A, a polarizer, and a (meth)acrylic resin film B in this order; and a pressure-sensitive adhesive layer provided on the (meth)acrylic resin film B of the polarizing laminate, When the polarizing laminate is exposed to an environment of 80°C for 2 hours, the polarizing laminate curls so that the surface on the thermoplastic resin film A side is convex and the surface on the (meth)acrylic resin film B is concave, or does not curl, the maximum curl force of the polarizing laminate during exposure to an environment at 80°C for 2 hours is 3 N or less, A polarizing plate, wherein the polarizing laminate has a dimensional shrinkage rate in the transmission axis direction of 1.25% or less before and after exposure to an environment at 80°C for 144 hours.

2. 2. The polarizing plate according to claim 1, wherein the thermoplastic resin film A is a polyester resin film or a (meth)acrylic resin film.

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