Curable adhesive composition and polarizing plate

Abstract

The present invention provides a curable adhesive composition suitable for bonding of a polarizing plate and a thermoplastic resin film, and a polarizing plate which sequentially comprises a polarizing plate, an adhesive layer, and a thermoplastic resin film and has good adhesion between the polarizing plate and the thermoplastic resin film. The present invention provides a curable adhesive composition, and a polarizing plate which sequentially comprises a polarizing plate, an adhesive layer, and a thermoplastic resin film and the adhesive layer is a cured product layer of the above-mentioned curable adhesive composition, the above-mentioned curable adhesive composition comprising a maleic anhydride-modified compound (A), a (meth)acrylate compound (B), and a photopolymerization initiator (C), the (meth)acrylate compound (B) comprising a monofunctional (meth)acrylate compound (B-1), the monofunctional (meth)acrylate compound (B-1) comprising a (meth)acrylic alicyclic alkyl ester compound and a (meth)acrylic linear or branched C 36 alkyl ester compound.

Description

TECHNICAL FIELD

[0001] The present application relates to a curable adhesive composition and a polarizing plate. BACKGROUND

[0002] A polarizing plate which is widely used in image display devices such as liquid crystal display devices and organic EL display devices generally has a constitution in which a thermoplastic resin film such as a protective film is attached to one side or both sides of a polarizing film. The attachment of the polarizing film to the thermoplastic resin film is usually performed using an adhesive. As the adhesive, a curable adhesive for active energy rays, a water-based adhesive (for example, Japanese Patent Application Laid-Open No. 2009-008860 (Patent Document 1)) is known.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-008860 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] An object of the present application is to provide a curable adhesive composition which is suitable for the attachment of a polarizing film to a thermoplastic resin film. Another object of the present application is to provide a polarizing plate which comprises a polarizing film, an adhesive layer and a thermoplastic resin film in this order, and in which the adhesion of the polarizing film to the thermoplastic resin film is excellent.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] The present application provides a curable adhesive composition and a polarizing plate as shown below.

[0010] [1] A curable adhesive composition comprising a maleic anhydride-modified compound (A), a (meth)acrylate compound (B) and a photopolymerization initiator (C),

[0011] The above (meth)acrylate compound (B) comprises a monofunctional (meth)acrylate compound (B-1),

[0012] The above monofunctional (meth)acrylate compound (B-1) comprises a (meth)acrylic alicyclic alkyl ester compound and a (meth)acrylic linear or branched C4-C 36 alkyl ester compound.

[0013] [2] The curable adhesive composition according to [1], wherein the content of the above monofunctional (meth)acrylate compound (B-1) is 60 mass% or more and 99 mass% or less in 100 mass% of the above (meth)acrylate compound (B).

[0014] [3] The curable adhesive composition according to [1] or [2], wherein the (meth)acrylate cyclic alkyl ester compound and the (meth)acrylate linear or branched C4-C4 bond is formed in the C4-C4 bond of the above-mentioned (meth)acrylate cyclic alkyl ester compound and the above-mentioned (meth)acrylate linear or branched C4-C4 bond. 36 Of the total alkyl ester compounds, the content of the above-mentioned (meth)acrylate cyclic alkyl ester compounds is 5% or more and 80% or less per 100% by mass.

[0015] [4] The curable adhesive composition according to any one of [1] to [3] further comprises unmodified polybutadiene (D).

[0016] [5] According to the curable adhesive composition described in [4], wherein, in 100% by mass of the total amount of the maleic anhydride modified compound (A) and the unmodified polybutadiene (B), the content of the maleic anhydride modified compound (A) is 40% by mass or more and 90% by mass or less.

[0017] [6] The curing adhesive composition according to any one of [1] to [5] further comprises petroleum resin (E).

[0018] [7] The curable adhesive composition according to any one of [1] to [6], wherein the maleic anhydride modified compound (A) comprises a maleic anhydride modified polymer (A-1).

[0019] [8] A curable adhesive composition according to any one of [1] to [7], wherein a cured film comprising the above-mentioned curable adhesive composition with a thickness of 10 μm has a curing strength of 400 g / (m²) at a temperature of 40°C and a relative humidity of 90%. 2 • 24hr) or less of permeability.

[0020] [9] A polarizing plate, comprising, in sequence, a polarizing film, an adhesive layer, and a thermoplastic resin film.

[0021] The adhesive layer described above is the cured layer of any of the curable adhesive compositions described in [1] to [8].

[0022]

[10] According to the polarizing plate described in [9], the thermoplastic resin film is a (meth)acrylic resin film.

[0023] Invention Effects

[0024] A curable adhesive composition suitable for bonding a polarizer to a thermoplastic resin film is provided; and a polarizing plate comprising a polarizer, an adhesive layer and a thermoplastic resin film in sequence, wherein the polarizer and the thermoplastic resin film have good adhesion. Attached Figure Description

[0025] Figure 1is a schematic cross-sectional view showing one example of a layer constitution of a polarizing plate of the present application.

[0026] Figure 2 is a schematic cross-sectional view showing another example of a layer constitution of a polarizing plate of the present application. DETAILED DESCRIPTION

[0027] <Curable adhesive composition>

[0028] The curable adhesive composition of the present application (hereinafter, also referred to as "adhesive composition") is suitable for the adhesion of a thermoplastic resin film, and for example, can be used for the lamination of a thermoplastic resin film with another thermoplastic resin film (or layer). One example of the application of the adhesive composition of the present application is for a polarizing plate, that is, can be used for the production of a polarizing plate. More specifically, the adhesive composition of the present application is useful as an adhesive composition for the lamination of a polarizing sheet with a thermoplastic resin film.

[0029] In the present specification, a polarizing plate refers to a laminated optical film comprising a polarizing sheet and a thermoplastic resin film laminated to one or both faces thereof. In the polarizing plate, the polarizing sheet and the above-mentioned thermoplastic resin film are laminated via an adhesive layer. The adhesive layer is a layer formed from an adhesive composition, and more specifically, a layer of a cured product of an adhesive composition.

[0030] The polarizing plate can comprise a film or layer other than the polarizing sheet and the above-mentioned thermoplastic resin film.

[0031] The above-mentioned adhesive composition is a curable adhesive composition comprising a maleic anhydride-modified compound (A), a (meth)acrylate compound (B), and a photopolymerization initiator (C). The adhesive composition can comprise components other than these.

[0032] Note that, in the present specification, the compounds exemplified as each component to be contained or can be contained in the adhesive composition can be used alone or in combination of a plurality of kinds, unless otherwise specified.

[0033] 〔1〕Maleic anhydride-modified compound (A)

[0034] The maleic anhydride-modified compound (A) is a compound containing a maleic anhydride structure within the molecule. The adhesive composition can contain one maleic anhydride-modified compound (A), or can contain two or more maleic anhydride-modified compounds (A).

[0035] As the maleic anhydride-modified compound (A), a maleic anhydride-modified polymer (A-1) can be exemplified.

[0036] The maleic anhydride-modified polymer (A-1) is a polymer modified by introducing a maleic anhydride structure as a side chain of the polymer. The adhesive composition can contain one maleic anhydride-modified polymer (A-1), or two or more maleic anhydride-modified polymers (A-1).

[0037] The maleic anhydride structure is a structure represented by the following formula.

[0038] [Chemical Formula 1]

[0039]

[0040] (* indicates a bonding bond to the main chain.)

[0041] In the maleic anhydride-modified polymer (A-1), as the polymer modified by maleic anhydride, mention can be made of diene-based polymers, polyolefin-based polymers, (meth)acrylic-based polymers, polyester-based polymers, polystyrene-based polymers, polyether-based polymers, and the like. These polymers can be homopolymers composed of one monomer, or copolymers composed of two or more monomers.

[0042] In the present specification, "(meth)acrylic acid" means at least one selected from the group consisting of acrylic acid and methacrylic acid. The same applies to the expressions such as "(meth)acryloyl group" and "(meth)acrylate".

[0043] The maleic anhydride-modified polymer (A-1) is preferably a maleic anhydride-modified polybutadiene. These polymers can each be a homopolymer or a copolymer. When a copolymer, the comonomer is, for example, an olefin monomer.

[0044] The polybutadiene can be a 1,4-polybutadiene, or a 1,2-polybutadiene, or can contain both a structural unit formed by 1,4-addition and a structural unit formed by 1,2-addition. The 1,4-addition can be trans-addition, or cis-addition.

[0045] From the viewpoint of being able to produce an adhesive composition which is solvent-free and has good adhesive ability, the maleic anhydride-modified polymer (A-1) is preferably liquid. Liquid means that flowability is exhibited at a temperature of 25°C.

[0046] From the viewpoint of obtaining an adhesive composition which has good coatability, the maleic anhydride-modified polymer (A-1) in liquid form has a viscosity at 25°C of usually 1 Pa-sec or more and 1300 Pa-sec or less, preferably 10 Pa-sec or more and 1000 Pa-sec or less, more preferably 15 Pa-sec or more and 700 Pa-sec or less, and further preferably 15 Pa-sec or more and 150 Pa-sec or less.

[0047] The number average molecular weight of the maleic anhydride-modified polymer (A-1) is usually 500 or more and 15,000 or less, and from the viewpoint of viscosity and coatability, it is preferably 600 or more and 12,000 or less, more preferably 700 or more and 10,000 or less, and further preferably 2,000 or more and 10,000 or less.

[0048] The number average molecular weight of the maleic anhydride-modified polymer (A-1) can be measured as a standard polystyrene conversion value based on gel permeation chromatography (GPC).

[0049] The acid value of the maleic anhydride-modified polymer (A-1) is usually 10 KOH mg / g or more and 200 KOH mg / g or less, and from the viewpoint of the adhesion ability of the adhesive composition to the thermoplastic resin film (or layer) and the like, it is preferably 15 KOH mg / g or more and 150 KOH mg / g or less, more preferably 20 KOH mg / g or more and 100 KOH mg / g or less, and further preferably 45 KOH mg / g or more and 80 KOH mg / g or less. The use of a maleic anhydride-modified polymer (A-1) having an acid value within this range is advantageous in improving the adhesion ability of the adhesive composition to the thermoplastic resin film (or layer), and in particular, in the case where a polyvinyl alcohol-based polarizing plate is used as the polarizing plate, it is advantageous in providing an adhesive composition having high adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film.

[0050] The acid value of the maleic anhydride-modified polymer (A-1) is measured by the neutralization titration method with phenothalin as an indicator according to JIS K 0070:1992.

[0051] The content of the maleic anhydride-modified compound (A) is usually 3% by mass or more and 40% by mass or less, and from the viewpoint of the adhesion ability of the adhesive composition to the thermoplastic resin film (or layer), and in particular, in the case where a polyvinyl alcohol-based polarizing plate is used as the polarizing plate, the viewpoint of improving the adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film, it is preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less, when the total amount of the adhesive composition is taken as 100% by mass.

[0052] 〔2〕 (METH) ACRYLATE COMPOUND (B)

[0053] The (meth) acrylate compound (B) is a radical polymerizable compound having one or more (meth) acryloyloxy groups in the molecule.

[0054] The adhesive composition contains one or two or more (meth) acrylate compounds (B).

[0055] As the (meth)acrylate compound (B), a monofunctional (meth)acrylate compound (B-1) having one (meth)acryloyloxy group in the molecule, a difunctional (meth)acrylate compound (B-2) having two (meth)acryloyloxy groups in the molecule, and a polyfunctional (meth)acrylate compound (B-3) having three or more (meth)acryloyloxy groups in the molecule can be mentioned.

[0056] The (meth)acrylate compound (B) can contain one or two or more kinds of the monofunctional (meth)acrylate compound (B-1), the difunctional (meth)acrylate compound (B-2), and the polyfunctional (meth)acrylate compound (B-3), respectively.

[0057] One example of the monofunctional (meth)acrylate compound (B-1) is an alkyl (meth)acrylate. As the alkyl (meth)acrylate, a (meth)acrylic acid methyl ester, a (meth)acrylic acid ethyl ester, a (meth)acrylic acid n-propyl ester, a (meth)acrylic acid isopropyl ester, a (meth)acrylic acid n-butyl ester, a (meth)acrylic acid isobutyl ester, a (meth)acrylic acid t-butyl ester, a (meth)acrylic acid 2-ethylhexyl ester, a (meth)acrylic acid nonyl ester, a (meth)acrylic acid decyl ester, a (meth)acrylic acid isodecyl ester, a (meth)acrylic acid tetradecyl ester, a (meth)acrylic acid undecyl ester, a (meth)acrylic acid dodecyl ester, a (meth)acrylic acid lauryl ester, a (meth)acrylic acid cetyl ester, a (meth)acrylic acid stearyl ester, a (meth)acrylic acid isostearyl ester, a (meth)acrylic acid isomyristyl ester, a (meth)acrylic acid behenyl ester, and the like (straight-chain or branched alkyl (meth)acrylate compounds) can be mentioned.

[0058] As another example of the monofunctional (meth)acrylate compound (B-1), a compound which is the following compound and is other than the above-mentioned compound, and the like can be mentioned.

[0059] (meth)acrylic acid benzyl ester and the like (aromatic alkyl (meth)acrylate compounds), and (meth)acrylic acid 2-phenoxyethyl ester, phenoxyethanol (meth)acrylate, (meth)acrylic acid 2-hydroxy-3-phenoxypropyl ester, ethoxylated o-phenylphenol (meth)acrylate, and the like (phenoxy (meth)acrylate compounds) having a group bonded to the -O- of the ester bond (-C(=O)-O-) containing an aromatic ring;

[0060] (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid cyclohexylmethyl ester, (meth)acrylic acid dicyclopentyl ester, 1,4-cyclohexanedimethanol mono(meth)acrylate, (meth)acrylic acid isobornyl ester, and the like (alicyclic alkyl (meth)acrylate compounds) having a group bonded to the -O- of the ester bond (-C(=O)-O-) containing an alicyclic ring;

[0061] N,N-dimethylaminoethyl (meth)acrylate, and the like (aminoalkyl (meth)acrylate compounds);

[0062] Dicyclopentenyloxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and the like (meth)acrylate compounds in which the group bonded to the -O- of the ester bond (-C(=O)-O-) contains an ether bond.

[0063] As another example of the monofunctional (meth)acrylate compound (B-1), for example, N,N-dimethylaminoethyl (meth)acrylate, and the like (aminoalkyl (meth)acrylate compounds) can be given.

[0064] 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, pentaerythritol mono(meth)acrylate, and the like (meth)acrylate compounds in which the group bonded to the -O- of the ester bond (-C(=O)-O-) contains a hydroxyl group;

[0065] 2-carboxyethyl (meth)acrylate, ω-carboxy-polycaprolactone (n≈2) mono(meth)acrylate, 1-[2-(meth)acryloyloxyethyl]phthalate, 1-[2-(meth)acryloyloxyethyl]hexahydrophthalate, 1-[2-(meth)acryloyloxyethyl]succinate, 4-[2-(meth)acryloyloxyethyl]trimellitate, N-(meth)acryloyloxy-N',N'-dicarboxymethyl-p-phenylenediamine, and the like (meth)acrylate compounds in which the group bonded to the -O- of the ester bond (-C(=O)-O-) contains a carboxyl group.

[0066] As the 2-functional (meth)acrylate compound (B-2), for example, an alkylene glycol di(meth)acrylate, a polyoxyalkylene glycol di(meth)acrylate, a halogen-substituted alkylene glycol di(meth)acrylate, a di(meth)acrylate of an aliphatic polyol, a di(meth)acrylate of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, a di(meth)acrylate of dioxane glycol or dioxane dialkanol, a di(meth)acrylate of an alkylene oxide adduct of bisphenol A or bisphenol F, an epoxy di(meth)acrylate of bisphenol A or bisphenol F, and the like can be given.

[0067] If more specific examples of the 2-functional (meth)acrylate compound (B-2) are given, there are ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, silicone di(meth)acrylate, di(meth)acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis[4-(meth)acryloyloxyethoxyethoxycyclohexyl]propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 1,3-dioxan-2,5-diyl di(meth)acrylate (alternative name: dioxaneglycol di(meth)acrylate), di(meth)acrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane (chemical name: 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane), tris(hydroxyethyl)isocyanurate di(meth)acrylate, di(meth)acrylate of ethoxylated bisphenol A, di(meth)acrylate of propoxylated bisphenol A, di(meth)acrylate of ethoxylated bisphenol F, di(meth)acrylate of propoxylated bisphenol F, and the like.

[0068] The 2-functional (meth)acrylate (B-2) preferably has at least one alicyclic skeleton or at least one aromatic ring in the molecule, more preferably at least one aromatic ring.

[0069] The 2-functional (meth)acrylate (B-2) preferably contains a compound represented by the following formula, more preferably a compound represented by the following formula, from the viewpoint of moisture permeability of the cured product, compatibility with the maleic anhydride-modified compound (A), and adhesion to a thermoplastic resin film (particularly, a (meth)acrylic resin film).

[0070] [Chemical Formula 2]

[0071]

[0072] (In the formula, R1and R2each independently represent a hydrogen atom or a methyl group, X represents an oxirane (-C2H4O-) or an oxetane (-C3H6O-), n represents an integer of 1 to 20, and m represents an integer of 1 to 20.)

[0073] X is preferably an oxirane, and in addition, the average of the total of m and n is preferably from 2 to 20, more preferably from 3 to 15, and further preferably from 4 to 13.

[0074] As the multifunctional (meth)acrylate compound (B-3) having 3 or more (meth)acryloyloxy groups in the molecule, there can be mentioned glycerol tri(meth)acrylate, alkoxylated glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like;

[0075] a multifunctional (meth)acrylate compound of a halogen-substituted polyol having 3 or more functions;

[0076] a tri(meth)acrylate of an alkylene oxide adduct of glycerol;

[0077] a tri(meth)acrylate of an alkylene oxide adduct of trimethylolpropane;

[0078] 1,1,1-tris[(meth)acryloyloxyethoxyethoxy]propane;

[0079] tris(hydroxyethyl)isocyanurate tri(meth)acrylate, and the like.

[0080] From the viewpoint of reducing the viscosity of the adhesive composition, the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and the viewpoint of the moisture heat resistance of a polarizing plate using a polyvinyl alcohol-based polarizing plate, i.e., the viewpoint of providing a polarizing plate in which the adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film is good even after being placed in a moisture heat environment, the (meth)acrylate compound (B) contains a monofunctional (meth)acrylate compound (B-1).

[0081] When the total amount of the (meth)acrylate compound (B) is taken as 100% by mass, the content of the monofunctional (meth)acrylate compound (B-1) is usually 60% by mass or more, and from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and the viewpoint of the moisture heat resistance of a polarizing plate using a polyvinyl alcohol-based polarizing plate, it is preferably 70% by mass or more, and more preferably 80% by mass or more.

[0082] The content of the monofunctional (meth)acrylate compound (B-1) can be 100% by mass, provided that the total amount of the (meth)acrylate compound (B) is 100% by mass, but from the viewpoint of the mechanical strength of the cured product of the adhesive composition, and further the mechanical strength of the polarizing plate produced using the adhesive composition, it is preferably 99% by mass or less, more preferably 98% by mass or less, and can be 90% by mass or less.

[0083] In the case where the content of the monofunctional (meth)acrylate compound (B-1) is less than 100% by mass, the remaining portion of the (meth)acrylate compound (B) is a difunctional (meth)acrylate compound (B-2) and / or a multifunctional (meth)acrylate compound (B-3), and preferably contains the difunctional (meth)acrylate compound (B-2).

[0084] From the viewpoint of reducing the viscosity of the adhesive composition, the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and the viewpoint of the hygrothermal durability of the polarizing plate using a polyvinyl alcohol-based polarizing plate, the monofunctional (meth)acrylate compound (B-1) contains a (meth)acrylic alicyclic alkyl ester compound and a (meth)acrylic straight-chain or branched C4-C 36 alkyl ester compound, and preferably consists of a (meth)acrylic alicyclic alkyl ester compound and a (meth)acrylic straight-chain or branched C4-C 36 alkyl ester compound.

[0085] As the (meth)acrylic straight-chain or branched C4-C 36 alkyl ester compound, for example, (meth)acrylic acid butyl ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid isodecyl ester, (meth)acrylic acid undecyl ester, (meth)acrylic acid dodecyl ester, (meth)acrylic acid lauryl ester, (meth)acrylic acid cetyl ester, (meth)acrylic acid stearyl ester, (meth)acrylic acid isostearyl ester, (meth)acrylic acid isomyristyl ester, (meth)acrylic acid behenyl ester, (meth)acrylic acid myristyl ester, and the like can be given.

[0086] From the viewpoint of the hygrothermal durability of the polarizing plate using a polyvinyl alcohol-based polarizing plate, the number of carbon atoms of the (meth)acrylic straight-chain or branched C4-C 36 alkyl ester compound is preferably 8 or more, more preferably 10 or more, and particularly preferably 12 or more. The number of carbon atoms can be 24 or less, or 22 or less.

[0087] From the viewpoint of the adhesive ability of the adhesive composition and the viewpoint of the hygrothermal durability of the polarizing plate using a polyvinyl alcohol-based polarizing plate, the content of the (meth)acrylic alicyclic alkyl ester compound is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 70% by mass or less, further preferably 15% by mass or more and 60% by mass or less, further preferably 20% by mass or more and 50% by mass or less, in 100% by mass of the total amount of the (meth)acrylic straight-chain or branched C4-C10 alkyl ester compound. 36 The content of the (meth)acrylic alicyclic alkyl ester compound is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 70% by mass or less, further preferably 15% by mass or more and 60% by mass or less, further preferably 20% by mass or more and 50% by mass or less, in 100% by mass of the total amount of the (meth)acrylic straight-chain or branched C4-C10 alkyl ester compound.

[0088] The content of the (meth)acrylic ester compound (B) is usually 15% by mass or more and 75% by mass or less, preferably 15% by mass or more and 70% by mass or less, more preferably 20% by mass or more and 60% by mass or less, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer).

[0089] 〔3〕Photopolymerization initiator (C)

[0090] The photopolymerization initiator (C) is not particularly limited as long as it is a compound capable of generating a living radical, an acid, or the like by the action of light and initiating the polymerization of the (meth)acrylic ester compound (B).

[0091] The adhesive composition can contain only one photopolymerization initiator (C) or two or more.

[0092] The photopolymerization initiator (C) is not particularly limited, and examples include oxime-based compounds such as O-acyl oxime compounds, alkyl phenone compounds, and acyl phosphine oxide compounds.

[0093] The O-acyl oxime compound is a compound having the structure shown in the following formula (d). Hereinafter, * represents a bonding bond.

[0094] [Chemical Formula 3]

[0095]

[0096] As the O-acyl oxime compound, N-benzoyloxy-1-(4-phenylsulfanylphenyl)butane-1- ketone-2-imine, N-benzoyloxy-1-(4-phenylsulfanylphenyl)octane-1-ketone-2-imine, N- benzoyloxy-1-(4-phenylsulfanylphenyl)-3-cyclopentylpropane-1-ketone-2-imine, N- acetyloxy-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethane-1-imine, N-acetyloxy-1- [9-ethyl-6-{2-methyl-4-(3,3-dimethyl-2,4-dioxolanylmethoxy)benzoyl}-9H-carbazol-3-yl] ethane-1-imine, N-acetyloxy-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-3- cyclopentylpropane-1-imine, N-benzoyloxy-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3- yl]-3-cyclopentylpropane-1-ketone-2-imine, N-acetyloxy-1-[4-(2-hydroxyethoxy)phenylsulfanylphenyl]propane-1-ketone-2-imine, N-acetyloxy-1-[4-(1-methyl-2- methoxyethoxy)-2-methylphenyl]-1-(9-ethyl-6-nitro-9H-carbazol-3-yl)methane-1-imine, and the like can be mentioned.

[0097] Commercially available products such as Irgacure (trade name) OXE01, Irgacure OXE02, Irgacure OXE03 (manufactured by BASF Corporation), N-1919, NCI-930, NCI-831 (manufactured by ADEKA Corporation), and the like can also be used.

[0098] The alkylphenone compound is a compound having a partial structure represented by the following formula (d4) or a partial structure represented by the following formula (d5). In these partial structures, the benzene ring can have a substituent.

[0099] [Chemical Formula 4]

[0100]

[0101] As the compound having the structure represented by formula (d4), 2-methyl-2-morpholino-1-(4- methylsulfanylphenyl)propane-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutane-1- ketone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]butane-1- ketone, and the like can be mentioned.

[0102] Commercially available products such as Omnirad (trade name) 369, Omnirad 907, Omnirad 379 (manufactured by IGM Resins B.V. Corporation), and the like can also be used.

[0103] As the compound having a structure represented by formula (d5), 2-hydroxy-2-methyl-l-phenylpropan-l-one, 2-hydroxy-2-methyl-l-〔4-(2-hydroxyethoxy)phenyl〕propan-l-one, 1-hydroxycyclohexyl phenyl ketone, an oligomer of 2-hydroxy-2-methyl-l-(4-isopropenylphenyl)propan-l-one, α,α-diethoxyacetophenone, benzil dimethyl ketal, and the like can be mentioned.

[0104] Commercially available products such as Omnirad (trade name) 184 (manufactured by IGM Resins B.V.) can also be used.

[0105] As the acylphosphine oxide compound, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (for example, trade name "Omnirad 819" (manufactured by IGM Resins B.V.)), 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the like can be mentioned.

[0106] As further examples of the photopolymerization initiator (C), the following can be mentioned:

[0107] benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and the like benzoin compounds;

[0108] benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl diphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4,4'-di(N,N'-dimethylamino)-benzophenone, and the like benzophenone compounds;

[0109] xanthone compounds such as 2-isopropylthioxanthone, 2,4-diethylthioxanthone, and the like;

[0110] anthracene compounds such as 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 2-ethyl-9,10-diethoxyanthracene, and the like;

[0111] quinone compounds such as 9,10-phenanthrenequinone, 2-ethylanthraquinone, camphorquinone, and the like;

[0112] benzil, phenyl glyoxylate methyl ester, titanocene compounds, and the like.

[0113] The content of the photopolymerization initiator (C) is usually 0.1 mass% or more and 20 mass% or less, preferably 0.5 mass% or more and 15 mass% or less, and more preferably 1 mass% or more and 10 mass% or less (for example, 8 mass% or less), based on 100 mass% of the total amount of the adhesive composition, from the viewpoint of the curability of the adhesive composition and the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer).

[0114] The content of the photopolymerization initiator (C) is usually 0.1 parts by mass or more and 30 parts by mass or less, preferably 0.5 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total amount of the (meth)acrylate compound (B), from the viewpoint of the curability of the adhesive composition and the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer).

[0115] 〔4〕Unmodified polybutadiene (D)

[0116] The adhesive composition can further contain an unmodified polybutadiene (D). It is advantageous for the adhesive composition to further contain the unmodified polybutadiene (D) from the viewpoint of the adhesive ability of the adhesive composition and the viewpoint of the moisture heat resistance of the polarizing plate using the polyvinyl alcohol-based polarizing plate.

[0117] The unmodified polybutadiene (D) is a polybutadiene which is not modified, and is a polymer obtained by addition polymerization of 1,3-butadiene. Unmodified means that no reactive group or polar group is contained in the side chain. The adhesive composition can contain one unmodified polybutadiene, or two or more unmodified polybutadienes.

[0118] The unmodified polybutadiene (D) can be 1,4-polybutadiene, or 1,2-polybutadiene, or can contain both a structural unit formed by 1,4-addition (1,4-addition unit) and a structural unit formed by 1,2-addition (1,2-addition unit). The 1,4-addition can be trans-addition, or cis-addition.

[0119] In the case where the unmodified polybutadiene (D) contains both the 1,4-addition unit and the 1,2-addition unit, the content of each of them is usually 1,4-addition unit / 1,2-addition unit = 50 to 95 / 50 to 5, preferably 70 to 90 / 30 to 10, and more preferably 75 to 90 / 25 to 10, in terms of molar ratio.

[0120] The proportion of the vinyl group contained in the unmodified polybutadiene (B) is preferably 35% or less, more preferably 30% or less, preferably 1% or more, and more preferably 10% or more.

[0121] The unmodified polybutadiene (D) is preferably liquid in order to produce an adhesive composition which is solvent-free and has good adhesion. Liquid means that it exhibits fluidity at 25°C.

[0122] The unmodified polybutadiene (D) is preferably liquid in order to produce an adhesive composition which is solvent-free and has good adhesion. Liquid means that it exhibits fluidity at 25°C.

[0123] The unmodified polybutadiene (D) is preferably liquid in order to produce an adhesive composition which is solvent-free and has good adhesion. Liquid means that it exhibits fluidity at 25°C.

[0124] The number average molecular weight of the unmodified polybutadiene (D) can be measured as a polystyrene conversion value based on GPC.

[0125] The unmodified polybutadiene (D) is preferably liquid in order to produce an adhesive composition which is solvent-free and has good adhesion. Liquid means that it exhibits fluidity at 25°C.

[0126] The unmodified polybutadiene (D) is preferably liquid in order to produce an adhesive composition which is solvent-free and has good adhesion. Liquid means that it exhibits fluidity at 25°C.

[0127] In the case where the adhesive composition contains the unmodified polybutadiene (D), the content of the unmodified polybutadiene (D) is usually 5% by mass or more and 65% by mass or less, preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, based on 100% by mass of the total amount of the maleic anhydride-modified compound (A) and the unmodified polybutadiene (D) in the adhesive composition, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and particularly from the viewpoint of improving the adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film in the case where the polyvinyl alcohol-based polarizing plate is used as the polarizing plate.

[0128] In the case where the adhesive composition contains the unmodified polybutadiene (D), the content of the maleic anhydride-modified compound (A) is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 80% by mass or less, based on 100% by mass of the total amount of the maleic anhydride-modified compound (A) and the unmodified polybutadiene (D) in the adhesive composition, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and particularly from the viewpoint of improving the adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film in the case where the polyvinyl alcohol-based polarizing plate is used as the polarizing plate.

[0129] 〔5〕Tackifier

[0130] The adhesive composition can further contain a tackifier. The tackifier resin is not particularly limited and can be appropriately selected from publicly known tackifier resins, and for example, rosin derivatives (e.g., rosin, polymerized rosin, hydrogenated rosin), terpene-based resins (e.g., terpene resin, aromatic-modified terpene resin, terpene phenol resin, hydrogenated terpene resin), petroleum resins, phenol-based resins, xylene-based resins, and the like can be given.

[0131] Among them, the adhesive composition preferably further contains a petroleum resin (E). By further containing the petroleum resin (E) in the adhesive composition, the adhesion can be improved, and the moisture permeability of the cured film formed from the adhesive composition can be reduced.

[0132] The adhesive composition capable of forming a cured film having low moisture permeability is suitable for use in which it is required to suppress the passage of moisture through the cured film. For example, in a polarizing plate in which a thermoplastic resin film is laminated to at least one side of a polarizing plate via an adhesive layer, or an image display panel containing the polarizing plate, if the adhesive layer is low in moisture permeability, the curling (warping) of the polarizing plate or the image display panel caused by the passage of moisture can be suppressed.

[0133] Further, the adhesive composition further containing the petroleum resin (E) is also advantageous in improving the adhesion between the polarizing plate and the thermoplastic resin film.

[0134] As the petroleum resin (E), aromatic petroleum resins, aliphatic petroleum resins, cyclic aliphatic petroleum resins, aliphatic-aromatic petroleum resins, coumarone resins, and the like can be given. In addition, resins obtained by hydrogenating these resins, and the like can also be given.

[0135] The aromatic petroleum resins are resins containing one or two or more structural units derived from aromatic hydrocarbons, and can be resins obtained by hydrogenating the resins, or resins obtained by modifying the resins.

[0136] The aromatic petroleum resins are preferably C9 petroleum resins. The C9 petroleum resins are resins obtained by copolymerizing a C9 fraction, and can be resins obtained by hydrogenating the resins, or resins obtained by modifying the resins.

[0137] The C9 petroleum resins can also be resins obtained by copolymerizing a C9 fraction with other monomer components, and can be resins obtained by hydrogenating the resins, or resins obtained by modifying the resins. As the other monomer components, a C5 fraction can be given.

[0138] As the C9 fraction, for example, petroleum fractions having 8 to 10 or so carbon atoms, such as styrene, alkylstyrene, vinyltoluene, 1-methyl-1-phenylethylene, indene, methylindene, and the like can be given.

[0139] As the C5 fraction, for example, petroleum fractions having 4 to 5 or so carbon atoms, such as cyclopentadiene, pentene, pentadiene, isoprene, piperylene, and the like can be given.

[0140] In addition, the petroleum resin (E) can be a C5 petroleum resin obtained by copolymerizing the above-described C5 fraction, a resin obtained by hydrogenating the C5 petroleum resin, or a resin obtained by modifying the resin. Furthermore, an alicyclic hydrocarbon-based resin obtained by polymerizing a C5 fraction cyclodimer can also be given. As the alicyclic hydrocarbon-based resin, a polymer containing a structural unit derived from dicyclopentadiene, and the like can be given.

[0141] The weight average molecular weight of the petroleum resin (E) is usually 500 or more and 10,000 or less, and from the viewpoint of reducing the moisture permeability of a cured film formed from the adhesive composition, and the viewpoint of the adhesive ability of the adhesive composition to a thermoplastic resin film (or layer), it is preferably 500 or more and 7,000 or less, more preferably 600 or more and 5,000 or less, and further preferably 600 or more and 3,000 or less.

[0142] The weight average molecular weight of the petroleum resin (E) can be measured as a standard polystyrene conversion value based on GPC.

[0143] In the case where the adhesive composition contains the petroleum resin (E), the content of the petroleum resin (E) is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 65% by mass or less, based on 100% by mass of the total amount of the adhesive composition, from the viewpoint of reducing the moisture permeability of the cured film formed from the adhesive composition, and the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and particularly in the case where a polyvinyl alcohol-based polarizing plate is used as the polarizing plate, the viewpoint of improving the adhesion between the polyvinyl alcohol-based polarizing plate and the thermoplastic resin film.

[0144] The moisture permeability of the cured film formed from the adhesive composition is preferably low. The moisture permeability of the cured film having a thickness of 10 μm containing the adhesive composition is preferably 400 g / (m 2 ·24 hr) or less, more preferably 300 g / (m 2 ·24 hr) or less, and further preferably 200 g / (m 2 ·24 hr) or less, as measured by the cup method prescribed in JIS Z 0208 under conditions of a temperature of 40°C and a relative humidity of 90%. The moisture permeability is generally 1 g / (m 2 ·24 hr) or more, for example, 5 g / (m 2 ·24 hr) or more.

[0145] The moisture permeability J of the cured film containing the adhesive composition can be specifically obtained as follows: a laminate in which the cured film is formed on a substrate film whose moisture permeability is known is produced, the moisture permeability of the laminate is measured by the above-described method, and the measurement result is used to obtain based on the following equation.

[0146] 1 / Jt = (1 / J) + (1 / Jsub)

[0147] In the above equation, Jt is the moisture permeability of the above-described laminate, and Jsub is the moisture permeability of the above-described substrate film. The same substrate film as the thermoplastic resin film described later can be used as the substrate film. When the moisture permeability of the laminate is measured in accordance with JIS Z 0208, the above-described cured film is installed in the cup with the outside facing outward.

[0148] With respect to the above-described laminate, in the case where, for example, a (meth)acrylic resin film having a thickness of 60 μm is used as the above-described substrate film, the moisture permeability of the laminate of the (meth)acrylic resin film and the cured film having a thickness of 10 μm containing the adhesive composition is preferably 55 g / (m 2 ·24 hr) or less, more preferably 50 g / (m 2 ·24 hr) or less, as measured by the cup method prescribed in JIS Z 0208 under conditions of a temperature of 40°C and a relative humidity of 90%. The moisture permeability is generally 1 g / (m 2• 24hr or more, for example 5g / (m 2 ·24hr) or more.

[0149] [6] Other ingredients

[0150] The adhesive composition may contain other components besides those mentioned above.

[0151] Other components include curing agents other than (meth)acrylate compounds (C), crosslinking agents, coupling agents, antioxidants, UV absorbers, heat stabilizers, and other additives.

[0152] [7] Viscosity of the adhesive composition

[0153] The viscosity of the adhesive composition at 25°C is preferably 10,000 mPa·sec or less, more preferably 2 mPa·sec or more and 7,000 mPa·sec or less, and even more preferably 300 mPa·sec or more and 5,000 mPa·sec or less.

[0154] The viscosity of the adhesive composition at 25°C can be measured using an E-type viscometer.

[0155] <Polarizing plate>

[0156] The adhesive composition of the present invention described above is suitable for bonding thermoplastic resin films, for example, it can be used for laminating thermoplastic resin films to other thermoplastic resin films (or layers). An example application of the adhesive composition of the present invention is for use in polarizing plates, i.e., it can be used to manufacture polarizing plates. More specifically, the adhesive composition of the present invention is useful as an adhesive composition for laminating polarizing sheets to thermoplastic resin films such as protective films laminated thereon.

[0157] The polarizing plate of the present invention comprises a polarizing film and a thermoplastic resin film laminated on at least one side thereon by an adhesive layer formed of the above-described adhesive composition. The adhesive layer is a cured layer of the above-described adhesive composition.

[0158] Because the polarizing plate of the present invention uses the above-described adhesive composition to bond the polarizing film to the thermoplastic resin film, the adhesion between the polarizing film and the thermoplastic resin film is excellent, and the polarizing plate also exhibits good damp heat durability. In other words, according to the present invention, a polarizing plate with good adhesion between the polarizing film and the thermoplastic resin film can be provided even after being placed in a damp heat environment.

[0159] The polarizing plate of the present invention can be used in image display devices such as liquid crystal display devices and organic EL devices.

[0160] [1] Structure of polarizing plate

[0161] Examples of the layer constitution of the polarizing plate of the present application are shown in Figure 1 and Figure 2 .

[0162] As shown in Figure 1 , the polarizing plate of the present application can comprise, in order, the polarizing plate 30, the first adhesive layer 15, and the first thermoplastic resin film 10, i.e., the polarizing plate 30 and the first thermoplastic resin film 10 laminated and attached to one face thereof via the first adhesive layer 15.

[0163] The first adhesive layer 15 is preferably in direct contact with the first thermoplastic resin film 10.

[0164] The polarizing plate 30 is preferably in direct contact with the first adhesive layer 15.

[0165] In addition, as shown in Figure 2 , the polarizing plate of the present application can comprise the polarizing plate 30, the first thermoplastic resin film 10 laminated and attached to one face thereof via the first adhesive layer 15, and the second thermoplastic resin film 20 laminated and attached to the other face of the polarizing plate 30 via the second adhesive layer 25.

[0166] The first adhesive layer 15 is preferably in direct contact with the first thermoplastic resin film 10.

[0167] The polarizing plate 30 is preferably in direct contact with the first adhesive layer 15.

[0168] The second adhesive layer 25 is preferably in direct contact with the second thermoplastic resin film 20.

[0169] The polarizing plate 30 is preferably in direct contact with the second adhesive layer 25.

[0170] In the case where the polarizing plate has the first adhesive layer 15 and the second adhesive layer 25, either one of the adhesive layers can be formed of the adhesive composition of the present application, or both of the adhesive layers can be formed of the adhesive composition of the present application. The adhesive layer formed of the adhesive composition of the present application is preferably the adhesive layer on the visible side (the adhesive layer away from the adhesive layer described later).

[0171] In the case where both of the adhesive layers are formed of the adhesive composition of the present application, the adhesive compositions can be the same composition or different compositions.

[0172] The present application is not limited to Figure 1 and Figure 2Examples, the polarizing plate of the present application can contain other layers (or films) than the above. As the other layers, for example, an adhesive layer laminated to the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizing plate 30; a separator film (also referred to as a "release film") laminated to the outer surface of the adhesive layer; a protective film (also referred to as a "surface protective film") laminated to the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizing plate 30; an optical functional film (or layer) laminated to the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizing plate 30 via an adhesive layer, an adhesive layer, and the like can be given.

[0173] 〔2〕Polarizing plate

[0174] The polarizing plate 30 is a film having a function of selectively transmitting linearly polarized light in a certain direction from natural light. As the polarizing plate 30, for example, an iodine-based polarizing plate in which a polyvinyl alcohol-based resin film is adsorbed with iodine as a dichroic dye and oriented, a dye-based polarizing plate in which a polyvinyl alcohol-based resin film is adsorbed with a dichroic dye as a dichroic dye and oriented, and a coated polarizing plate obtained by coating a dichroic dye in a lyotropic liquid crystal state and orienting, immobilizing it, and the like can be given. These polarizing plates are called absorption-type polarizing plates because they selectively transmit linearly polarized light in a certain direction from natural light and absorb linearly polarized light in the other direction.

[0175] The polarizing plate 30 is not limited to an absorption-type polarizing plate, and can be a reflection-type polarizing plate that selectively transmits linearly polarized light in a certain direction from natural light and reflects linearly polarized light in the other direction, or a scattering-type polarizing plate that scatters linearly polarized light in the other direction, but from the aspect of excellent visuality when the polarizing plate is applied to an image display device or the like, an absorption-type polarizing plate is preferred.

[0176] Among them, the polarizing plate 30 is more preferably a polyvinyl alcohol-based polarizing plate composed of a polyvinyl alcohol-based resin, further preferably a polyvinyl alcohol-based polarizing plate obtained by adsorbing a dichroic dye such as iodine or a dichroic dye to a polyvinyl alcohol-based resin film and orienting it, and particularly preferably a polyvinyl alcohol-based polarizing plate obtained by adsorbing iodine to a polyvinyl alcohol-based resin film and orienting it.

[0177] The polyvinyl alcohol-based polarizing plate can be manufactured using a polyvinyl alcohol-based resin film (or layer) by a method known in the art.

[0178] The thickness of the polarizing plate 30 can be set to 30 μm or less, preferably 25 μm or less (for example, preferably 20 μm or less, further preferably 15 μm or less, still further preferably 10 μm or less, yet further preferably 8 μm or less). The thickness of the polarizing plate 30 is usually 2 μm or more. Reducing the thickness of the polarizing plate 30 is advantageous for thinning of the polarizing plate, and further, an image display device or the like using the polarizing plate.

[0179] 〔3〕 Thermoplastic resin film

[0180] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can each be a film containing a thermoplastic resin having light transmittance (preferably, optical transparency), for example, a film containing a polyolefin-based resin such as a chain polyolefin-based resin (polyethylene resin, polypropylene-based resin, etc.), a cyclic polyolefin-based resin (norbornene-based resin, etc.); a cellulose ester-based resin such as triacetyl cellulose, diacetyl cellulose, etc.; a polyester-based resin such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.; a polycarbonate-based resin; a (meth)acrylic-based resin; or a mixture, copolymer, etc. thereof.

[0181] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can each be any of a film that has not been stretched, or a film that has been uniaxially or biaxially stretched. The biaxial stretching can be simultaneous biaxial stretching in which stretching is performed simultaneously in two stretching directions, or sequential biaxial stretching in which stretching is performed in a first direction and then in a second direction different from the first direction.

[0182] The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can be a protective film that functions to protect the polarizing plate 30, or a protective film that has an optical function such as a phase difference film.

[0183] For example, by stretching (uniaxial stretching or biaxial stretching, etc.) a film containing the above-described thermoplastic resin, or forming a liquid crystal layer, etc. on the thermoplastic resin film, a phase difference film that imparts an arbitrary phase difference value can be produced.

[0184] The (meth)acrylic-based resin can be, for example, a polymer containing 50% by mass or more of a methacrylate ester as a main monomer, and is preferably a copolymer obtained by copolymerizing a methacrylate ester with another copolymerization component.

[0185] In one embodiment, the (meth)acrylic-based resin contains a methyl methacrylate ester as a copolymerization component, or contains a methyl methacrylate ester and a methyl acrylate ester as copolymerization components.

[0186] As other copolymerization components other than methyl acrylate, for example, ethyl methacrylate, n-butyl, isobutyl or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate and the like methacrylate esters other than methyl methacrylate can be mentioned;

[0187] ethyl acrylate, n-butyl, isobutyl or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate and the like acrylate esters;

[0188] methyl 2-(hydroxymethyl)acrylate, methyl 2-(1-hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, n-butyl, isobutyl or t-butyl 2-(hydroxymethyl)acrylate and the like hydroxyalkyl acrylate esters;

[0189] unsaturated acids such as methacrylic acid and acrylic acid;

[0190] halogenated styrenes such as chlorostyrene and bromostyrene;

[0191] substituted styrenes such as vinyltoluene and α-methylstyrene;

[0192] unsaturated nitriles such as acrylonitrile and methacrylonitrile;

[0193] unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride;

[0194] unsaturated imides such as phenylmaleimide and cyclohexylmaleimide; and monofunctional monomers.

[0195] The above other monofunctional monomers can be used singly or in combination of two or more.

[0196] As the above other copolymerization components, a polyfunctional monomer can be used.

[0197] As the polyfunctional monomer, for example, compounds in which both terminal hydroxyl groups of ethylene glycol or its oligomer are esterified with (meth)acrylic acid, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate and tetradecaethylene glycol di(meth)acrylate can be mentioned;

[0198] compounds in which both terminal hydroxyl groups of propylene glycol or its oligomer are esterified with (meth)acrylic acid;

[0199] compounds in which the hydroxyl groups of a dihydric alcohol are esterified with (meth)acrylic acid, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate and butanediol di(meth)acrylate.

[0200] a compound in which both terminal hydroxyl groups of bisphenol A, an alkylene oxide adduct of bisphenol A, or a halogen-substituted product thereof are esterified with (meth)acrylic acid;

[0201] a compound in which a polyhydric alcohol such as trimethylolpropane or pentaerythritol is esterified with (meth)acrylic acid, and a compound in which the epoxy group of glycidyl (meth)acrylate is ring-opening added to the terminal hydroxyl group thereof;

[0202] a compound in which the epoxy group of glycidyl (meth)acrylate is ring-opening added to a divalent acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid, a halogen-substituted product thereof, or an alkylene oxide adduct thereof;

[0203] an aryl (meth)acrylate; an aromatic divinyl compound such as divinylbenzene; and the like.

[0204] Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

[0205] The (meth)acrylic resin can be a resin modified by a reaction between functional groups possessed by a copolymer. As the reaction, for example, a high-molecular chain intramolecular dehydration condensation reaction of a methyl ester group of methyl (meth)acrylate with a hydroxyl group of 2-(hydroxymethyl) methyl acrylate, a high-molecular chain intramolecular dehydration condensation reaction of a carboxyl group of (meth)acrylic acid with a hydroxyl group of 2-(hydroxymethyl) methyl acrylate, and the like can be given.

[0206] The glass transition temperature of the (meth)acrylic resin is preferably 80°C or higher and 160°C or lower. The glass transition temperature can be controlled by adjusting the polymerization ratio of the methacrylate monomer and the acrylate monomer, the carbon chain length of each ester group and the kind of functional groups they possess, and the polymerization ratio of the multifunctional monomer with respect to the total monomers.

[0207] As a method for increasing the glass transition temperature of the (meth)acrylic resin, it is also effective to introduce a ring structure into the main chain of the polymer. The ring structure is preferably a heterocyclic structure such as a cyclic anhydride structure, a cyclic imide structure, and a lactone structure. Specifically, a cyclic anhydride structure such as glutaric anhydride structure, succinic anhydride structure; a cyclic imide structure such as glutaric imide structure, succinic imide structure; a lactone ring structure such as butyrolactone, valerolactone can be given.

[0208] The greater the content of the ring structure present in the main chain, the greater the tendency to increase the glass transition temperature of the (meth)acrylic resin.

[0209] The cyclic anhydride structure and the cyclic imide structure can be introduced by, for example, a method of introducing by copolymerization of a monomer having a cyclic structure such as maleic anhydride or maleimide; a method of introducing the cyclic anhydride structure by dehydration-methanol elimination condensation reaction after polymerization; and a method of introducing the cyclic imide structure by reaction with an amino compound.

[0210] The resin (polymer) having a lactone ring structure can be obtained by, after a polymer having a hydroxyl group and an ester group in a high molecular chain is prepared, cyclizing and condensing the hydroxyl group and the ester group in the obtained polymer by heating in the presence of a catalyst such as an organophosphorus compound to form a lactone ring structure.

[0211] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can contain an additive as needed. As the additive, for example, a lubricant, an anti-blocking agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, an impact resistance improver, a surfactant, and the like can be mentioned.

[0212] From the viewpoint of film-forming properties in film formation, impact resistance of the film, and the like, the (meth)acrylic resin can contain an acrylic rubber particle as an impact resistance improver. The acrylic rubber particle refers to a particle having an elastic polymer mainly composed of an acrylic ester as a necessary component, and examples of the acrylic rubber particle include a single-layer structure particle formed substantially only of the elastic polymer, and a multi-layer structure particle having the elastic polymer as one layer.

[0213] As an example of the elastic polymer, a crosslinked elastic copolymer obtained by copolymerizing an alkyl acrylate as a main component, and other vinyl monomers copolymerizable therewith and a crosslinking monomer can be mentioned.

[0214] As the alkyl acrylate as a main component of the elastic polymer, for example, an alkyl acrylate having an alkyl group having 1 or more and 8 or less carbon atoms such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate can be mentioned, and an alkyl acrylate having an alkyl group having 4 or more carbon atoms is preferably used.

[0215] As the other vinyl monomer copolymerizable with the above alkyl acrylate, a compound having one polymerizable carbon-carbon double bond in the molecule can be mentioned, and more specifically, a methacrylate such as methyl methacrylate; an aromatic vinyl compound such as styrene; a vinyl cyanide compound such as acrylonitrile; and the like can be mentioned.

[0216] As the crosslinkable monomer described above, a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule can be mentioned, and more specifically, (meth)acrylate esters of polyhydric alcohols such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate; allyl esters of (meth)acrylic acid such as allyl (meth)acrylate; and the like can be mentioned.

[0217] At least either one of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is preferably a film containing a (meth)acrylic resin ((meth)acrylic resin film), which is preferably laminated and attached to the polarizing plate 30 by the adhesive layer formed from the adhesive composition of the present application.

[0218] The adhesive composition of the present application can particularly exhibit good adhesion when the thermoplastic resin film is a (meth)acrylic resin film. Therefore, the adhesive composition of the present application can be suitably used for the attachment of a polarizing plate to a (meth)acrylic resin film.

[0219] The (meth)acrylic resin film preferably has a resin component containing a (meth)acrylic resin.

[0220] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be films composed of the same thermoplastic resin, or films composed of different thermoplastic resins from each other. The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be the same or different in thickness, presence or absence of additives, kind of additives, phase difference characteristics, and the like.

[0221] In one embodiment, the first thermoplastic resin film 10 is a (meth)acrylic resin film, and the second thermoplastic resin film 20 is a polyolefin-based resin film (preferably a cyclic polyolefin-based resin film), a cellulose ester-based resin, or a polyester-based resin film.

[0222] In another embodiment, the first thermoplastic resin film 10 and the second thermoplastic resin film 20 are (meth)acrylic resin films.

[0223] The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can have a surface treatment layer (coating layer) such as a hard coat layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an antistatic layer, a stain-proof layer, a conductive layer, or the like on the outer surface (surface on the side opposite to the polarizing plate 30).

[0224] The thicknesses of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 are typically 5 μm or more and 200 μm or less, preferably 10 μm or more and 120 μm or less, more preferably 10 μm or more and 85 μm or less, and even more preferably 15 μm or more and 65 μm or less. The thicknesses of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be 50 μm or less, or 40 μm or less. Reducing the thickness of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is beneficial for the thinning of polarizing plates, and consequently, for image display devices using such polarizing plates.

[0225] From the perspective of improving adhesion, the surfaces of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 coated with the adhesive composition can be subjected to surface modification treatments such as saponification, plasma treatment, corona treatment, and primer treatment.

[0226] [4] Manufacturing of polarizing plate and adhesive layer

[0227] By laminating and bonding the first thermoplastic resin film 10 to one side of the polarizer 30 via the first adhesive layer 15, a result can be obtained. Figure 1 The polarizing plate shown can be further modified by laminating and bonding a second thermoplastic resin film 20 to the other side of the polarizing plate 30 using a second adhesive layer 25. Figure 2 The polarizing plate shown is configured as follows.

[0228] In manufacturing a polarizing plate having a first thermoplastic resin film 10 and a second thermoplastic resin film 20 (hereinafter, they are also simply referred to as "thermoplastic resin films"), these thermoplastic resin films can be laminated and bonded one side at a time in stages, or the thermoplastic resin films on both sides can be laminated and bonded simultaneously.

[0229] exist Figure 1 In the polarizing plate shown, the first adhesive layer 15 is formed of the adhesive composition of the present invention. The first adhesive layer 15 is a cured layer of the adhesive composition of the present invention.

[0230] exist Figure 2 In the polarizing plate shown, at least one of the first adhesive layer 15 and the second adhesive layer 25 is formed of the adhesive composition of the present invention. The first adhesive layer 15 and / or the second adhesive layer 25 are cured layers of the adhesive composition of the present invention.

[0231] exist Figure 2 In the polarizing plate shown, either the first adhesive layer 15 or the second adhesive layer 25 can be formed by the adhesive composition of the present invention, and the other can be formed by an adhesive composition different from the adhesive composition of the present invention.

[0232] As other adhesive compositions, water-based adhesives or active energy ray-curable adhesives conventionally known can be given.

[0233] As the water-based adhesive, for example, an adhesive composition conventionally known using a polyvinyl alcohol-based resin or a urethane resin as a main component can be given.

[0234] The active energy ray-curable adhesive is an adhesive which is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, X-rays, and the like. In the case of using the active energy ray-curable adhesive, the adhesive layer possessed by the polarizing plate is a cured product layer of the adhesive.

[0235] The active energy ray-curable adhesive can be an adhesive containing an epoxy-based compound which is cured by cationic polymerization as a curable component, and is preferably an ultraviolet ray-curable adhesive containing the epoxy-based compound as a curable component. The epoxy-based compound refers to a compound having 1 or more, preferably 2 or more, epoxy groups in the molecule on average. The epoxy-based compound can be used alone or in combination with two or more kinds.

[0236] As the epoxy-based compound, a hydrogenated epoxy-based compound (glycidyl ether of a polyol having an alicyclic ring) obtained by subjecting epichlorohydrin to a hydrogenation reaction with respect to the aromatic ring of an aromatic polyol; an alicyclic epoxy-based compound which is an epoxy-based compound having 1 or more epoxy groups in the molecule which are bonded to an alicyclic ring; an aliphatic epoxy-based compound such as a polyglycidyl ether of an aliphatic polyol or an epoxy alkane adduct thereof; and the like can be given.

[0237] In the active energy ray-curable adhesive, as the curable component, a (meth)acrylic compound which is radically polymerizable can be contained instead of or together with the above-described epoxy-based compound. As the (meth)acrylic compound, a (meth)acrylate monomer having 1 or more (meth)acryloyloxy groups in the molecule; a (meth)acrylate oligomer having 2 or more (meth)acryloyloxy groups in the molecule obtained by subjecting two or more kinds of compounds containing a functional group to a reaction; and the like containing a (meth)acryloyloxy group can be given.

[0238] In the case where the active energy ray-curable adhesive contains an epoxy-based compound which is cured by cationic polymerization as a curable component, a photocationic polymerization initiator is preferably contained. As the photocationic polymerization initiator, for example, an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt, an aromatic sulfonium salt, and the like; an iron-arene complex; and the like can be given.

[0239] In the case where the active energy ray-curable adhesive contains a radical polymerizable component such as a (meth)acrylic compound, a photoradical polymerization initiator is preferably contained. As the photoradical polymerization initiator, for example, a phenylacetone-based initiator, a benzophenone-based initiator, a benzoin ether-based initiator, a thioxanthone-based initiator, an xanthone, a fluorenone, camphorquinone, benzaldehyde, anthraquinone, or the like can be given.

[0240] The adhesion of the polarizing plate 30 to the thermoplastic resin film can include a process of applying an adhesive composition to the bonding surface of the polarizing plate 30 and / or the bonding surface of the thermoplastic resin film, or injecting the adhesive composition between the polarizing plate 30 and the thermoplastic resin film, and laminating the films by the layer of the adhesive composition, for example, by pressing from above and below using a bonding roll or the like.

[0241] The formation of the adhesive composition layer can utilize various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, or the like. Alternatively, it can be a method of continuously supplying the polarizing plate 30 and the thermoplastic resin film with the bonding surfaces of both inside, and casting the adhesive composition therebetween.

[0242] Before the application of the adhesive composition, one or both of the bonding surfaces of the polarizing plate 30 and the thermoplastic resin film can be subjected to an easy adhesion treatment (surface activation treatment) such as a saponification treatment, a corona discharge treatment, a plasma treatment, a flame treatment, a primer treatment, an anchor coating treatment, or the like.

[0243] In the case of using an active energy ray-curable adhesive, the adhesive composition layer is cured by irradiation of active energy rays.

[0244] The light source for irradiation of active energy rays can be any light source capable of generating ultraviolet rays, electron beams, X-rays, or the like. It is particularly suitable to use, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light, a microwave-excited mercury lamp, a metal halide lamp, or the like, which has an emission distribution at a wavelength of 400 nm or less.

[0245] The thickness of the adhesive layer formed from the adhesive composition of the present application is, for example, 0.1 μm or more and 100 μm or less in the polarizing plate, preferably 0.5 μm or more and 80 μm or less, more preferably 1 μm or more and 60 μm or less, and further preferably 2 μm or more and 50 μm or less. From the viewpoint of thinning of the polarizing plate, it is also preferable to set the thickness of the adhesive layer to 30 μm or less, and further preferably to 20 μm or less.

[0246] The thickness of the first adhesive layer 15 and the second adhesive layer 25 can be the same or different.

[0247] 〔5〕Other Constituent Elements of the Polarizing Plate

[0248] [5-1] Optical functional films

[0249] The polarizer may have other optically functional films besides the polarizer 30 to impart the desired optical function; a suitable example is a phase retardation film.

[0250] As described above, the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can also serve as a phase retardation film, but a phase retardation film can also be laminated separately from the thermoplastic resin film. In the latter case, the phase retardation film can be laminated on the outer surface of the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 by means of an adhesive layer and a bonding agent layer.

[0251] Examples of phase retardation films include birefringent films made of a stretched film of a thermoplastic resin with light transmittance; films formed by orienting and fixing a disk-shaped liquid crystal or a nematic liquid crystal; and films on which the above-mentioned liquid crystal layer is formed on a substrate film.

[0252] The substrate film is typically a film containing a thermoplastic resin, an example of which is a cellulose ester resin such as triacetyl cellulose.

[0253] The thermoplastic resin described for the first and second thermoplastic resin films 10 and 20 can be used as the thermoplastic resin for forming the birefringent film.

[0254] Examples of other optical functional films (optical components) that can be included in a polarizing plate include a light-concentrating plate, a brightness enhancement film, a reflective layer (reflective film), a semi-transparent reflective layer (semi-transparent reflective film), and a light-diffusing layer (light-diffusing film). These are typically provided when the polarizing plate is disposed on the back side (backlight side) of the liquid crystal cell.

[0255] [5-2] Adhesive layer

[0256] The polarizing plate of the present invention may include an adhesive layer for bonding it to image display elements such as liquid crystal cells, organic EL elements, or other optical components. The adhesive layer is... Figure 1 The polarizing plate shown can be stacked on the outer surface of the polarizer 30. Figure 2 The polarizing plate shown can be laminated on the outer surface of the first thermoplastic resin film 10 or the second thermoplastic resin film 20.

[0257] As an adhesive used in the adhesive layer, adhesives based on polymers such as (meth)acrylic resins, silicone resins, polyester resins, polyurethane resins, and polyether resins can be used. Among these, (meth)acrylic adhesives are preferred from the viewpoints of transparency, adhesion, reliability, weather resistance, heat resistance, and reprocessability.

[0258] The thickness of the adhesive layer is determined in accordance with its adhesive force and the like, and a range of 1 μm or more and 50 μm or less is appropriate, and preferably 2 μm or more and 40 μm or less.

[0259] The polarizing plate can include a separation film laminated to the outer surface of the adhesive layer. The separation film can be a film including a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate, or the like. Among them, a stretched film of polyethylene terephthalate is preferable.

[0260] The adhesive layer can include, as necessary, glass fibers, glass beads, resin beads, fillers including metal powder, other inorganic powder, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like.

[0261] [5-3] Protective Film

[0262] The polarizing plate of the present application can include a protective film for protecting the surface thereof (the surface of the thermoplastic resin film, the surface of the polarizing plate, or the like). The protective film is, for example, peeled off together with the adhesive layer possessed thereby after the polarizing plate is attached to an image display element or other optical member.

[0263] The protective film is, for example, composed of a base film and an adhesive layer laminated thereon. As for the adhesive layer, the above-described description is cited.

[0264] The resin constituting the base film can be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, a polycarbonate-based resin, or the like. A polyester-based resin such as polyethylene terephthalate is preferable.

[0265] Example

[0266] Hereinafter, the present application will be described more specifically by showing examples, but the present application is not limited to these examples. In the examples, % and parts indicating the content or the amount of use are mass-based unless otherwise specified. The thickness of the film and the adhesive layer (cured film) was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

[0267] Example 1

[0268] (1) Preparation of the curable adhesive composition

[0269] The components shown in Table 1 were mixed in the amounts shown in Table 1 to prepare the curable adhesive composition A. The amounts of the components shown in Table 1 are in mass parts.

[0270] The details of the components shown in Table 1 are as described below.

[0271] (A): Liquid maleic anhydride-modified polybutadiene (trade name "Lithene ultra N4-5000-10MA" manufactured by Synthomer, number average molecular weight: 5500, viscosity at 25°C: 25 to 60 Pa-sec, acid value: 54 mgKOH / g)

[0272] (B-1a): Dicyclopentyl acrylate (trade name "FA-513AS" manufactured by Hitachi Chemical Co., Ltd.)

[0273] (B-1b): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0274] (B-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Co., Ltd., EO 10 moles)

[0275] (C): Phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.)

[0276] (D): Unmodified liquid polybutadiene (trade name "Lithene ultra PM4" manufactured by Synthomer, number average molecular weight: 1500, viscosity at 25°C: 0.7 to 0.95 Pa-sec)

[0277] (E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Corporation, hydrogenated resin (alicyclic saturated hydrocarbon resin having dicyclopentadiene as a monomer component), softening point (nominal value): 104.5°C, weight average molecular weight (nominal value): 610)

[0278] (2) Production of Polarizing Plate

[0279] A surface of a polymethyl methacrylate (PMMA) film having a thickness of 60 μm was subjected to corona treatment, and the cured adhesive composition A prepared in the above (1) was applied to the corona-treated surface using an adhesive applicator. The resulting applied layer was laminated with a polyvinyl alcohol-iodine-based polarizing plate having a thickness of 23 μm using a nip roll, to obtain a polarizing plate with a PMMA film.

[0280] Next, the surface of a phase difference film (trade name "ZEONOR" manufactured by ZEON Corporation) having a thickness of 50 μm and containing a cyclic polyolefin-based resin was subjected to a corona treatment, and a curable adhesive composition B prepared according to the following was applied to the corona-treated surface using an adhesive applicator. The resulting applied layer was laminated with the polarizing plate side of a polarizing plate with a PMMA film using a nip roll to obtain a laminate. A polarizing plate was produced by curing the layer of the curable adhesive composition B and the layer of the curable adhesive composition A using ultraviolet rays (UVA) having a total cumulative light quantity (accumulated quantity of light irradiation intensity in the wavelength region of wavelengths of 320 to 400 nm) of about 200 mJ / cm 2 (assay device: measured value based on UV Power Puck II manufactured by Fusion UV Systems) to cure the layer of the curable adhesive composition B and the layer of the curable adhesive composition A, and a polarizing plate was produced. Note that the thickness of the cured layer of the curable adhesive composition A was about 10 μm, and the thickness of the cured layer of the curable adhesive composition B was 2.5 μm.

[0281] The curable adhesive composition B was prepared by adding 1,4-butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase Chemtex Corporation) 25 parts by mass and a photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Corporation) 5.6 parts by mass to 3,4-epoxycyclohexane carboxylic acid 3',4'-epoxycyclohexyl methyl ester (trade name "Celloxide 2021P" manufactured by Daicel Corporation) 100 parts by mass and mixing.

[0282] Examples 2 to 3 and Comparative Example 1

[0283] The curable adhesive composition A was prepared by changing the compounding amount of the compounding component as shown in Table 1, and otherwise, the same operation as in Example 1 was performed. In addition, using the curable adhesive composition A, a polarizing plate was produced in the same manner as in Example 1, except that.

[0284] <Assay and Evaluation>

[0285] (1) Moisture permeability of the cured film formed from the curable adhesive composition A

[0286] The curable adhesive composition A was applied to a PMMA film having a thickness of 60 μm on which a corona treatment was performed using an adhesive applicator.

[0287] An untreated polyethylene terephthalate (PET) film was laminated on the applied layer of the curable adhesive composition A, and the lamination was performed using a nip roll. Next, the total cumulative light quantity (accumulated quantity of light irradiation intensity in the wavelength region of wavelengths of 320 to 400 nm) of about 200 mJ / cm2 The adhesive layer was cured by ultraviolet rays (UVA) of a UV Power Puck II (measuring device: measured value based on UV Power Puck II manufactured by Fusion UV Systems, Inc.) to obtain a laminate having a layer structure of a PMMA film / cured adhesive layer / PET film. Then, the PET film was peeled off to obtain a laminate having a layer structure of a PMMA film / cured adhesive layer (cured film) (a sample for moisture permeability measurement).

[0288] For the obtained laminate (a sample for moisture permeability measurement), the moisture permeability at 40°C and 90% RH (g / (m 2 Note that, in the measurement, the cured adhesive layer (cured film) in the above laminate was left in an environment at 40°C and 90% RH. In addition, the laminate was installed in the cup with the cured film facing the outside.

[0289] The results are shown in the column of "Moisture permeability of laminate" in Table 1. The values in parentheses indicate the thickness of the cured film (unit: μm) possessed by the laminate.

[0290] In addition, using the moisture permeability (Jt) of the obtained laminate, the moisture permeability (J) of the cured film itself at 40°C and 90% RH was calculated based on the following equation.

[0291] 1 / Jt = (1 / J) + (1 / Jsub)

[0292] The moisture permeability (Jsub) of a PMMA film having a thickness of 60 μm as a base film, measured by the cup method prescribed in JIS Z 0208 at 40°C and 90% RH, was 70 g / (m 2 ·24hr).

[0293] The results are shown in the column of "Moisture permeability of cured film" in Table 1. The values in parentheses indicate the thickness of the cured film (unit: μm).

[0294] (2) Evaluation of adhesion between polarizing plate and PMMA film in polarizing plate (initial)

[0295] An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing plate) x 25 mm in width, and the adhesive layer was attached to a glass plate to obtain a laminate. The obtained laminate was placed in a high-temperature high-humidity environment at 80°C and 90% RH for 24 hours, and then placed in an environment at 23°C and 50% RH for 24 hours. Then, a cutter of a cutting machine was interposed between the polarizing plate and the PMMA film of the obtained laminate, and 30 mm was peeled from the end portion in the length direction. The peeled portion was gripped with a gripping portion of a tester, and the lower portion was gripped to grip the glass plate. For the test piece in this state, a peeling test was performed at a gripping moving speed of 300 mm / min in an atmosphere at 23°C and 55% RH in accordance with JIS K 6854-2: 1999 "Adhesives - Peel adhesion strength test method - Part 2: 180 degree peel", and the average peeling force on a length of 170 mm excluding 30 mm of the gripping portion was obtained as the peeling strength between the polarizing plate and the PMMA film. The results are shown in Table 1. The peeling strength was measured after the polarizing plate was left in an environment at 23°C and 50% RH for 24 hours.

[0296] In Table 1, "break" means that the peeling strength was very large, and the PMMA film or the polarizing plate was broken before the film was peeled. In Comparative Example 1, the adhesion between the polarizing plate and the PMMA film was too weak to measure the peeling strength.

[0297] (3) Evaluation of the adhesion between the polarizing plate and the PMMA film in the polarizing plate (after exposure to a high-temperature high-humidity environment)

[0298] An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing plate) x 25 mm in width, and the adhesive layer was attached to a glass plate to obtain a laminate. The obtained laminate was placed in a high-temperature high-humidity environment at 80°C and 90% RH for 24 hours, and then placed in an environment at 23°C and 50% RH for 24 hours. Then, a cutter of a cutting machine was interposed between the polarizing plate and the PMMA film of the obtained laminate, and 30 mm was peeled from the end portion in the length direction. The peeled portion was gripped with a gripping portion of a tester, and the lower portion was gripped to grip the glass plate. For the test piece in this state, a peeling test was performed at a gripping moving speed of 300 mm / min in an atmosphere at 23°C and 55% RH in accordance with JIS K 6854-2: 1999 "Adhesives - Peel adhesion strength test method - Part 2: 180 degree peel", and the average peeling force on a length of 170 mm excluding 30 mm of the gripping portion was obtained as the peeling strength between the polarizing plate and the PMMA film. The results are shown in Table 1. The peeling strength was measured after the polarizing plate was left in an environment at 23°C and 50% RH for 24 hours.

[0299] [Table 1]

[0300]

[0301] Example 4

[0302] (1) Preparation of the curable adhesive composition

[0303] A curable adhesive composition C was prepared by mixing the components shown in Table 2 at the mixing amounts shown in Table 2. The mixing amount of each component shown in Table 2 is in parts by mass.

[0304] Details of each component shown in Table 2 are described below.

[0305] (A): Maleic anhydride-modified liquid polybutadiene (trade name "Lithene ultra N4-5000-10MA" manufactured by Synthomer Co., Ltd., number average molecular weight: 5500, viscosity at 25°C: 25 to 60 Pa-sec, acid value: 54 mgKOH / g)

[0306] (B-la): Dicyclopentyl acrylate (trade name "FA-513AS" manufactured by Hitachi Chemical Co., Ltd.)

[0307] (B-lb): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0308] (B-lc): Lauryl acrylate (trade name "LA" manufactured by Osaka Organic Chemical Industry Ltd.)

[0309] (B-l d): Butyl acrylate (manufactured by FUJIFILM Wako Pure Chemical Corporation)

[0310] (B-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Co., Ltd., EO 10 moles)

[0311] (C): Phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.)

[0312] (D): Unmodified liquid polybutadiene (trade name "Lithene ultra PM4" manufactured by Synthomer Co., Ltd., number average molecular weight: 1500, viscosity at 25°C: 0.7 to 0.95 Pa-sec)

[0313] (E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Corporation, hydrogenated resin (alicyclic saturated hydrocarbon resin with dicyclopentadiene as a monomer component), softening point (nominal value): 104.5°C, weight average molecular weight (nominal value): 610)

[0314] (2) Production of Polarizing Plate

[0315] A surface of a poly(methyl methacrylate) (PMMA) film having a thickness of 60 μm was subjected to corona treatment, and the curable adhesive composition C prepared in the above (1) was applied to the corona-treated surface using an adhesive applicator. The resulting applied layer was laminated with a polyvinyl alcohol-iodine-based polarizing plate having a thickness of 23 μm using a nip roll to obtain a polarizing plate with a PMMA film.

[0316] Next, a surface of a phase difference film having a thickness of 50 μm containing a cyclic polyolefin-based resin (trade name "ZEONOR" manufactured by ZEON Corporation) was subjected to corona treatment, and the curable adhesive composition B prepared according to the following was applied to the corona-treated surface using an adhesive applicator. The resulting applied layer was laminated with the polarizing plate side of the polarizing plate with a PMMA film using a nip roll to obtain a laminate. The laminate was irradiated with ultraviolet rays (UVA) having a total cumulative light quantity (cumulative amount of light irradiation intensity in a wavelength region of wavelengths of 320 to 400 nm) of about 200 mJ / cm 2 (assay device: measured value based on UV Power Puck II manufactured by Fusion UV Systems) to cure the layer of the curable adhesive composition B and the layer of the curable adhesive composition C, and a polarizing plate was produced. Note that the thickness of the cured layer of the curable adhesive composition C was about 10 μm, and the thickness of the cured layer of the curable adhesive composition B was 2.5 μm.

[0317] The curable adhesive composition B was prepared by adding 1,4-butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase Chemtex Corporation) 25 parts by mass and a photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Corporation) 5.6 parts by mass to 3,4-epoxycyclohexane carboxylic acid 3',4'-epoxycyclohexyl methyl ester (trade name "Celloxide 2021P" manufactured by Daicel Corporation) 100 parts by mass and mixing.

[0318] <Example 5 to 8>

[0319] A curable adhesive composition C was produced by changing the compounding amounts of the compounding ingredients as shown in Table 2, and otherwise operating in the same manner as in Example 4. In addition, a polarizing plate was produced using the curable adhesive composition C, and otherwise in the same manner as in Example 4.

[0320] <Measurement and Evaluation>

[0321] (1) Moisture permeability of the cured film formed from the curable adhesive composition C

[0322] The curable adhesive composition C was applied to a PMMA film having a thickness of 60 μm on which a corona treatment was performed, using an adhesive applicator.

[0323] An untreated polyethylene terephthalate (PET) film was stacked on the applied layer of the curable adhesive composition C, and was laminated using a nip roll. Next, the adhesive layer was cured by irradiation with ultraviolet rays (UVA) having a total cumulative light amount (cumulative amount of light irradiation intensity in the wavelength region of wavelengths of 320 to 400 nm) of about 200 mJ / cm 2 A laminate having a layer constitution of a PMMA film / cured adhesive layer / PET film was obtained by curing the adhesive layer with ultraviolet rays (UVA) having a total cumulative light amount (cumulative amount of light irradiation intensity in the wavelength region of wavelengths of 320 to 400 nm) of about 200 mJ / cm

[0324] The moisture permeability of the obtained laminate (moisture permeability measurement sample) was measured by the cup method prescribed in JIS Z 0208 at a temperature of 40°C and a relative humidity of 90% (g / (m 2 Note that, in the measurement, the cured adhesive layer (cured film) in the above laminate was left in an environment at a temperature of 40°C and a relative humidity of 90%. In addition, the laminate was installed in the cup with the cured film facing the outside.

[0325] The results are shown in the column of "Moisture permeability of laminate" in Table 2. The values in parentheses indicate the thickness (unit: μm) of the cured film possessed by the laminate.

[0326] In addition, the moisture permeability (J) of the cured film itself at a temperature of 40°C and a relative humidity of 90% was calculated based on the following equation, using the moisture permeability (Jt) of the obtained laminate.

[0327] 1 / Jt = (1 / J) + (1 / Jsub)

[0328] The moisture permeability (Jsub) of a PMMA film having a thickness of 60 μm as a base film was 70 g / (m2·24 hr) measured by the cup method prescribed in JIS Z 0208 under conditions of a temperature of 40°C and a relative humidity of 90%. 2 ·24 hr).

[0329] The results are shown in the "Moisture permeability of cured film" column of Table 2. The values in parentheses represent the thickness of the cured film (unit: μm).

[0330] (2) Evaluation of the adhesion between the polarizing plate and the PMMA film in the polarizing plate (initial)

[0331] An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing plate) x 25 mm in width, and the adhesive layer was attached to a glass plate to obtain a laminate. The obtained laminate was used as a test piece for measuring the peeling strength between the polarizing plate and the PMMA film. The knife of a cutter was interposed between the polarizing plate and the PMMA film of the test piece, and the 30 mm from the end portion in the length direction was peeled, and the peeled portion was gripped by the gripping portion of the tester, and the lower portion was gripped for gripping the glass plate. The test piece in this state was subjected to a peeling test at a gripping moving speed of 300 mm / min in an atmosphere of a temperature of 23°C and a relative humidity of 55% in accordance with JIS K 6854-2: 1999 "Adhesives - Peel adhesion strength test method - Part 2: 180 degree peel", and the average peeling force over a length of 170 mm excluding the 30 mm of the gripping portion was calculated as the peeling strength between the polarizing plate and the PMMA film. The results are shown in Table 2. The peeling strength was measured after the polarizing plate was left to stand for 24 hours in an environment of a temperature of 23°C and a relative humidity of 50% RH.

[0332] In Table 2, "break" means that the peeling strength was very large, and the PMMA film or the polarizing plate was broken before the film was peeled.

[0333] (3) Evaluation of the adhesion between the polarizing plate and the PMMA film in the polarizing plate (after exposure to a high-temperature high-humidity environment)

[0334] An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing plate) x 25 mm in width, and the adhesive layer was attached to a glass plate to obtain a laminate. The obtained laminate was left in a high-temperature high-humidity environment at a temperature of 80°C and a relative humidity of 90% RH for 24 hours, and then left in an environment at a temperature of 23°C and a relative humidity of 50% RH for 24 hours. Then, a knife of a cutting machine was inserted between the polarizing plate and the PMMA film of the obtained laminate, and the 30 mm from the end in the length direction was peeled off, and the peeled portion was gripped with the gripping portion of a tester, and the lower portion was gripped for gripping the glass plate. For the test piece in this state, a peeling test was performed at a gripping moving speed of 300 mm / min in accordance with JIS K 6854-2: 1999 "Adhesives - Test methods for peel adhesion - Part 2: 180-degree peel" in an atmosphere at a temperature of 23°C and a relative humidity of 55%, and the average peeling force in a length of 170 mm excluding the 30 mm of the gripping portion was obtained as the peeling strength between the polarizing plate and the PMMA film. The results are shown in Table 2.

[0335] [Table 2]

[0336]

[0337] BRIEF DESCRIPTION OF DRAWINGS

[0338] 10: first thermoplastic resin film, 15: first adhesive layer, 20: second thermoplastic resin film, 25: second adhesive layer, 30: polarizing plate.

Claims

1. A curable adhesive composition comprising a maleic anhydride-modified compound A, a (meth)acrylate compound B, a photopolymerization initiator C, and an unmodified polybutadiene D, the (meth)acrylate compound B comprises a monofunctional (meth)acrylate compound B-1, The monofunctional (meth)acrylate compound B-1 contains a (meth)acrylic alicyclic alkyl ester compound and a (meth)acrylic straight-chain or branched C4-C 36 alkyl ester compound; wherein the content of the maleic anhydride-modified compound A is 50% by mass or more and 80% by mass or less in 100% by mass of the total amount of the maleic anhydride-modified compound A and the unmodified polybutadiene D; the maleic anhydride-modified compound A comprises a maleic anhydride-modified polymer A-1 which is a polymer modified by introducing a maleic anhydride structure as a side chain of a high molecule; wherein the content of the (meth)acrylic alicyclic alkyl ester compound is 5 mass% or more and 80 mass% or less in 100 mass% of the total amount of the (meth)acrylic alicyclic alkyl ester compound and the (meth)acrylic linear or branched C4-C 36 wherein the content of the (meth)acrylic alicyclic alkyl ester compound is 5 mass% or more and 80 mass% or less in 100 mass% of the total amount of the (meth)acrylic alicyclic alkyl ester compound and the (meth)acrylic linear or branched C4-C 2. The curable adhesive composition according to claim 1, wherein, the content of the monofunctional (meth)acrylate compound B-1 is 60% by mass or more and 99% by mass or less in 100% by mass of the (meth)acrylate compound B.

3. The curable adhesive composition according to claim 1 or 2, further comprising a petroleum resin E.

4. The curable adhesive composition according to claim 1 or 2, wherein The cured film of the curable adhesive composition having a thickness of 10 μm has a moisture permeability of 400 g / (m 2 ·24 hr) or less at a temperature of 40°C and a relative humidity of 90%.

5. A polarizing plate comprising, in this order, a polarizing sheet, an adhesive layer, and a thermoplastic resin film, the adhesive layer is a cured product layer of the curable adhesive composition according to any one of claims 1 to 4.

6. The polarizing plate according to claim 5, wherein the thermoplastic resin film is a (meth)acrylic resin film.

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