Curable adhesive composition and polarizing plate

Abstract

The present application 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. A curable adhesive composition comprising a maleic anhydride-modified compound (A), an unmodified polybutene (B), a (meth)acrylate compound (C), and a photopolymerization initiator (D), and a polarizing plate which sequentially comprises a polarizing plate, an adhesive layer, and a thermoplastic resin film and has the adhesive layer as a cured product layer of the above-mentioned curable adhesive composition are provided.

Description

Technical Field

[0001] This invention relates to curable adhesive compositions and polarizing plates. Background Technology

[0002] Polarizing plates, widely used in image display devices such as liquid crystal displays and organic EL displays, typically have a thermoplastic resin film, such as a protective film, laminated to one or both sides of the polarizing plate. The lamination of the polarizing plate to the thermoplastic resin film usually uses an adhesive. Known adhesives include active energy ray-curable adhesives and water-based adhesives (e.g., Japanese Patent Application Publication No. 2009-008860 (Patent Document 1)).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-008860 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The object of this invention is to provide a curable adhesive composition suitable for bonding polarizers to thermoplastic resin films. Another object of this invention is to provide a polarizing plate comprising, in sequence, a polarizer, an adhesive layer, and a thermoplastic resin film, wherein the polarizer and the thermoplastic resin film exhibit good adhesion.

[0008] Methods for solving problems

[0009] The present invention 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), unmodified polybutene (B), a (meth)acrylate compound (C) and a photopolymerization initiator (D).

[0011] [2] According to the curable adhesive composition described in [1], wherein, in 100% by mass of the above-mentioned maleic anhydride modified compound (A) and unmodified polybutene (B), the content of the above-mentioned maleic anhydride modified compound (A) is 40% by mass or more and 90% by mass or less.

[0012] [3] The curable adhesive composition according to [1] or [2], wherein the (meth)acrylate compound (C) comprises a monofunctional (meth)acrylate compound (C-1).

[0013] [4] According to the curable adhesive composition described in [3], in which the content of the monofunctional (meth)acrylate compound (C-1) is 60% or more and 99% or less in 100% by mass of the above-mentioned (meth)acrylate compound (C).

[0014] [5] The curable adhesive composition according to [3] or [4], wherein the monofunctional (meth)acrylate compound (C-1) comprises at least one compound selected from (meth)acrylate cycloalkyl ester compounds and aromatic (meth)acrylate compounds.

[0015] [6] The curable adhesive composition according to any one of [3] to [5], wherein the monofunctional (meth)acrylate compound (C-1) comprises a (meth)acrylate cycloalkyl ester compound and a (meth)acrylate straight-chain or branched C4-C5 chain. 36 Alkyl ester compounds.

[0016] [7] The curable adhesive composition according to [6], wherein the above-mentioned (meth)acrylate cyclic alkyl ester compound and the above-mentioned (meth)acrylate straight chain or branched chain C4-C 36 Of the total alkyl ester compounds, the content of the above-mentioned (meth)acrylate cyclic alkyl ester compounds is 30% or more and 80% or less per 100% by mass.

[0017] [8] The curing adhesive composition according to any one of [1] to [7] further comprises petroleum resin (E).

[0018] [9] The curable adhesive composition according to any one of [1] to [8], wherein the maleic anhydride modified compound (A) comprises a maleic anhydride modified polymer (A-1).

[0019]

[10] A curable adhesive composition according to any one of [1] to [9], 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 • Permeability of less than 24 hours.

[0020]

[11] 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

[10] .

[0022]

[12] According to the polarizing plate described in

[11] , the above-mentioned 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 1 This is a schematic cross-sectional view illustrating an example of the layered structure of the polarizing plate of the present invention.

[0026] Figure 2 This is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate of the present invention. Detailed Implementation

[0027] <Curing adhesive compositions>

[0028] The curable adhesive composition of the present invention (hereinafter also referred to as "adhesive composition") 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 of the application of the adhesive composition of the present invention is for use in polarizing plates, that is, 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 plates to thermoplastic resin films.

[0029] In this specification, a polarizing plate refers to a laminated optical film comprising a polarizer and a thermoplastic resin film stacked on one or both sides thereof. In the polarizing plate, the polarizer and the aforementioned thermoplastic resin film are laminated by an adhesive layer. The adhesive layer is a layer formed of an adhesive composition, and more specifically, a cured layer of the adhesive composition.

[0030] The polarizing plate may contain films or layers other than polarizing sheets and the aforementioned thermoplastic resin films.

[0031] The adhesive composition described above is a curable adhesive composition comprising a maleic anhydride-modified compound (A), unmodified polybutene (B), a (meth)acrylate compound (C), and a photopolymerization initiator (D). The adhesive composition may contain other components besides these.

[0032] It should be noted that, unless otherwise specified, the compounds exemplified in this specification as components contained in or may be contained in the adhesive composition may be used alone or in combination.

[0033] [1] Maleic anhydride modified compound (A)

[0034] Maleic anhydride modified compound (A) is a compound that contains a maleic anhydride structure within its molecule. The adhesive composition may contain one maleic anhydride modified compound (A) or two or more maleic anhydride modified compounds (A).

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

[0036] Maleic anhydride-modified polymer (A-1) is a polymer modified by introducing maleic anhydride structures as side chains of the polymer. The adhesive composition may contain one maleic anhydride-modified polymer (A-1) or two or more maleic anhydride-modified polymers (A-1).

[0037] The aforementioned maleic anhydride structure refers to the following structure.

[0038] [Chemical Formula 1]

[0039]

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

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

[0042] In this specification, "(meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. The same applies to the descriptions of "(meth)acryloyl" and "(meth)acrylate", etc.

[0043] The maleic anhydride-modified polymer (A-1) is preferably maleic anhydride-modified polybutadiene. These polymers can be either homopolymers or copolymers. When they are copolymers, the comonomers are, for example, olefin monomers.

[0044] Polybutadiene can be 1,4-polybutadiene or 1,2-polybutadiene, and can also contain both structural units formed by 1,4-addition and structural units formed by 1,2-addition. 1,4-addition can be trans-addition or cis-addition.

[0045] From the perspective of being able to prepare solvent-free adhesive compositions with good bonding ability, the maleic anhydride modified polymer (A-1) is preferably in liquid form. Liquid form means exhibiting fluidity at a temperature of 25°C.

[0046] From the viewpoint of obtaining an adhesive composition with good coatability, the viscosity of the liquid maleic anhydride modified polymer (A-1) at 25°C is generally 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 even more 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 typically 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 even more 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 determined 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 typically 10 KOH mg / g or higher and 200 KOH mg / g or lower. From the viewpoint of the adhesive composition's adhesion to thermoplastic resin films (or layers), an acid value of 15 KOH mg / g or higher and 150 KOH mg / g or lower is preferred, more preferably 20 KOH mg / g or higher and 100 KOH mg / g or lower, and even more preferably 45 KOH mg / g or higher and 80 KOH mg / g or lower. Using a maleic anhydride-modified polymer (A-1) with an acid value within this range is advantageous in improving the adhesive composition's adhesion to thermoplastic resin films (or layers), especially when using a polyvinyl alcohol-based polarizer as the polarizer, as it provides an adhesive composition with high adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film.

[0050] The acid value of the maleic anhydride modified polymer (A-1) was determined by neutralization titration using phenolphthalein as an indicator, according to JIS K 0070:1992.

[0051] When the total amount of the adhesive composition is set to 100% by mass, the content of maleic anhydride modified compound (A) is generally 3% by mass or more and 40% by mass or less. From the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), especially from the viewpoint of improving the adhesion between polyvinyl alcohol polarizers and thermoplastic resin films when using polyvinyl alcohol polarizers as polarizers, it is preferable to be 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.

[0052] [2] Unmodified polybutene (B)

[0053] Unmodified polybutene (B) is unmodified polybutene obtained through the addition polymerization of butene. Unmodified means that it does not contain reactive or polar groups in its side chains. The structural units derived from butene in unmodified polybutene (B) are preferably mainly derived from isobutene, but may further include structural units derived from n-butene. The adhesive composition may contain one type of unmodified polybutene, or two or more types of unmodified polybutene.

[0054] From the perspective of being able to prepare solvent-free adhesive compositions with good bonding ability, unmodified polybutene (B) is preferably in a liquid state. Liquid state means exhibiting fluidity at a temperature of 25°C.

[0055] From the viewpoint of obtaining an adhesive composition with good coatability, the viscosity of the liquid unmodified polybutene (B) at 25°C is preferably 0.01 Pa·sec or more and 5 Pa·sec or less, more preferably 0.02 Pa·sec or more and 3 Pa·sec or less, and even more preferably 0.03 Pa·sec or more and 2 Pa·sec or less.

[0056] The number average molecular weight of unmodified polybutene (B) is typically 200 or more and 1500 or less, and preferably 250 or more and 1000 or less, more preferably 300 or more and 600 or less, from the viewpoint of viscosity and coatability. The number average molecular weight of unmodified polybutene (B) can be determined by vapor pressure molecular weight determination.

[0057] When the total amount of the adhesive composition is set to 100% by mass, the content of unmodified polybutene (B) is generally 1% by mass or more and 20% by mass or less. From the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), especially from the viewpoint of improving the adhesion between polyvinyl alcohol polarizers and thermoplastic resin films when using polyvinyl alcohol polarizers as polarizers, it is preferable to be 2% by mass or more and 18% by mass or less, more preferably 3% by mass or more and 15% by mass or less.

[0058] When the total amount of the adhesive composition is set to 100% by mass, the combined amount of maleic anhydride modified compound (A) and unmodified polybutene (B) is generally 4% by mass or more and 60% by mass or less. From the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), especially from the viewpoint of improving the adhesion between polyvinyl alcohol polarizers and thermoplastic resin films when using polyvinyl alcohol polarizers as polarizers, it is preferable to be 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less.

[0059] When the total amount of maleic anhydride modified compound (A) and unmodified polybutene (B) in the adhesive composition is set to 100% by mass, the content of unmodified polybutene (B) is generally 5% by mass or more and 65% by mass or less. From the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), especially from the viewpoint of improving the adhesion between polyvinyl alcohol polarizers and thermoplastic resin films when using polyvinyl alcohol polarizers as polarizers, it is preferable to be 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less.

[0060] When the total amount of maleic anhydride modified compound (A) and unmodified polybutene (B) in the adhesive composition is set to 100% by mass, from the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), and especially from the viewpoint of improving the adhesion between polyvinyl alcohol polarizers and thermoplastic resin films when using polyvinyl alcohol polarizers as polarizers, the content of maleic anhydride modified compound (A) is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 80% by mass or less.

[0061] [3] (Meth)acrylate compounds (C)

[0062] (Meth)acrylate compounds (C) are free radical polymerizable compounds having one or more (meth)acryloyloxy groups in the molecule.

[0063] The adhesive composition may contain one or more (meth)acrylate compounds (C).

[0064] Examples of (meth)acrylate compounds (C) include monofunctional (meth)acrylate compounds (C-1) having one (meth)acryloyloxy group in the molecule, difunctional (meth)acrylate compounds (C-2) having two (meth)acryloyloxy groups in the molecule, and polyfunctional (meth)acrylate compounds (C-3) having three or more (meth)acryloyloxy groups in the molecule.

[0065] (Meth)acrylate compound (C) may contain one or more monofunctional (meth)acrylate compounds (C-1), difunctional (meth)acrylate compounds (C-2), and polyfunctional (meth)acrylate compounds (C-3).

[0066] An example of a monofunctional (meth)acrylate compound (C-1) is an alkyl (meth)acrylate. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecanyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, isomyristyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, and other straight-chain or branched alkyl ester compounds of (meth)acrylate.

[0067] Other examples of monofunctional (meth)acrylate compounds (C-1) include, for example:

[0068] Aromatic (meth)acrylate compounds such as benzyl (meth)acrylate, aralkyl (meth)acrylates, 2-phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, etc., whose phenoxy (meth)acrylate groups contain an aromatic ring and are bonded to an ester bond (-C(=O)-O-).

[0069] Cyclohexyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, 1,4-cyclohexanediethanol mono(meth)acrylate, isobornyl methacrylate, and other alicyclic alkyl methacrylate compounds whose groups bonded to the ester bond (-C(=O)-O-) include alicyclic rings.

[0070] (Meth)acrylate N,N-dimethylaminoethyl ester and other (meth)acrylate aminoalkyl ester compounds;

[0071] Dicyclopentenyloxyethyl methacrylate, ethyl carbitol methacrylate, tetrahydrofurfuryl methacrylate, and other (meth)acrylate compounds whose groups bonded to the -O- group of the ester bond (-C(=O)-O-) include ether bonds, and which are not mentioned above, are (meth)acrylate compounds.

[0072] Other examples of monofunctional (meth)acrylate compounds (C-1) include, for example:

[0073] 2-Hydroxyethyl methacrylate, 2- or 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, trimethylolpropane mono(meth)acrylate, pentaerythritol mono(meth)acrylate, and other (meth)acrylate compounds whose groups bonded to the -O- of the ester bond (-C(=O)-O-) include hydroxyl groups;

[0074] 2-Carboxyethyl methacrylate, 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]trimethacrylate, N-(meth)acryloyloxy-N',N'-dicarboxymethyl-p-phenylenediamine, and other (meth)acrylate compounds whose groups include carboxyl groups are bonded to the -O- group of the ester bond (-C(=O)-O-).

[0075] Examples of difunctional (meth)acrylate compounds (C-2) include alkylene glycol di(meth)acrylates, polyoxyalkylene glycol di(meth)acrylates, halogen-substituted alkylene glycol di(meth)acrylates, di(meth)acrylates of aliphatic polyols, di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecanediol, di(meth)acrylates of dioxanediol or dioxanediol, di(meth)acrylates of epoxide adducts of bisphenol A or bisphenol F, and epoxy di(meth)acrylates of bisphenol A or bisphenol F.

[0076] More specific examples of difunctional (meth)acrylate compounds (C-2) include ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane dimethacrylate, pentaerythritol dimethacrylate, bis(trimethylolpropane)dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polytetramethylene glycol dimethacrylate, organosilicon dimethacrylate, and di(meth)propylene of neopentyl glycol hydroxypentanoate. Ester, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis[4-(meth)acryloyloxyethoxyethoxycyclohexyl]propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, 1,3-dioxane-2,5-diyl di(meth)acrylate (also known as dioxanediol di(meth)acrylate), hydroxyneopental and trimethylolpropane Acetal compounds [chemical name: 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane] di(meth)acrylate, tri(hydroxyethyl)isocyanurate di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, propoxylated bisphenol F di(meth)acrylate, etc.

[0077] The 2-functional (meth)acrylate (C-2) preferably has at least one alicyclic skeleton or at least one aromatic ring in the molecule, more preferably at least one aromatic ring.

[0078] From the viewpoints of the moisture permeability of the cured product, its compatibility with the maleic anhydride modified compound (A), and its adhesion to thermoplastic resin films (especially (meth)acrylic resin films), the 2-functional (meth)acrylate (C-2) preferably contains the compound shown in the following formula, and more preferably the compound shown in the following formula.

[0079] [Chemical Formula 2]

[0080]

[0081] (In the formula, R1 and R2 each independently represent a hydrogen atom or a methyl group, X represents ethylene oxide (-C2H4O-) or propylene oxide (-C3H6O-), n represents an integer from 1 to 20, and m represents an integer from 1 to 20.)

[0082] X is preferably ethylene oxide, and the average of the sum of m and n is preferably 2 to 20, more preferably 3 to 15, and even more preferably 4 to 13.

[0083] Examples of polyfunctional (meth)acrylate compounds (C-3) having three or more (meth)acryloyloxy groups in the molecule include glycerol tri(meth)acrylate, alkoxylated glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, bis(trimethylolpropane tri(meth)acrylate, bis(trimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, which are poly(meth)acrylates of aliphatic polyols with three or more functions.

[0084] Poly(meth)acrylates of halogenated polyols with three or more functions;

[0085] Tri(meth)acrylate of glycerol alkyl oxide adduct;

[0086] Tri(meth)acrylate of the epoxide adduct of trimethylolpropane;

[0087] 1,1,1-Tris[(meth)acryloyloxyethoxyethoxy]propane;

[0088] Tris(hydroxyethyl) isocyanurate, tri(meth)acrylate, etc.

[0089] From the viewpoint of reducing the viscosity of the adhesive composition and the adhesive composition's ability to bond to thermoplastic resin films (or layers), the (meth)acrylate compound (C) preferably comprises a monofunctional (meth)acrylate compound (C-1).

[0090] When the total amount of (meth)acrylate compound (C) is set to 100% by mass, the content of monofunctional (meth)acrylate compound (C-1) is usually 60% by mass or more, and from the viewpoint of the adhesive composition's ability to adhere to thermoplastic resin films (or layers), it is preferably 70% by mass or more, and more preferably 80% by mass or more.

[0091] When the total amount of (meth)acrylate compound (C) is set to 100% by mass, the content of monofunctional (meth)acrylate compound (C-1) can be 100% by mass, but from the viewpoint of the mechanical strength of the cured adhesive composition and, more importantly, the mechanical strength of the polarizer made using the adhesive composition, it is preferable to be 99% by mass or less, more preferably 98% by mass or less, and can be 90% by mass or less.

[0092] When the content of monofunctional (meth)acrylate compound (C-1) is less than 100% by mass, the remaining portion of (meth)acrylate compound (C) is difunctional (meth)acrylate compound (C-2) and / or polyfunctional (meth)acrylate compound (C-3), preferably containing difunctional (meth)acrylate compound (C-2).

[0093] From the viewpoint of reducing the viscosity of the adhesive composition and the adhesive composition's ability to bond to thermoplastic resin films (or layers), the monofunctional (meth)acrylate compound (C-1) preferably contains at least one compound selected from (meth)acrylate cycloalkyl ester compounds and aromatic (meth)acrylate compounds.

[0094] Furthermore, from the viewpoint of the damp heat durability of polarizing plates using polyvinyl alcohol-based polarizers, that is, from the viewpoint of providing polarizing plates that maintain good adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film even after being placed in a damp heat environment, the monofunctional (meth)acrylate compound (C-1) preferably contains C4-C4 compounds selected from (meth)acrylate alicyclic alkyl ester compounds and (meth)acrylate linear or branched C4-C4 compounds. 36 At least one of the alkyl ester compounds, more preferably comprising an alicyclic alkyl ester compound of (meth)acrylate and a C4-C straight-chain or branched (meth)acrylate. 36 Alkyl ester compounds.

[0095] As a straight-chain or branched C4-C of (meth)acrylic acid 36 Alkyl ester compounds, for example, include butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, isomyristyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, etc.

[0096] From the perspective of the damp heat durability of polarizing plates using polyvinyl alcohol-based polarizers, the C4-C4 bonds of (meth)acrylic acid, whether linear or branched, are important factors. 36 The alkyl ester compound preferably has 8 or more carbon atoms, more preferably 10 or more, and particularly preferably 12 or more. The number of carbon atoms may be 24 or less, or 22 or less.

[0097] The monofunctional (meth)acrylate compound (C-1) comprises a (meth)acrylate cycloalkyl ester compound and a straight-chain or branched (meth)acrylate C4-C5 group. 36In the case of alkyl ester compounds, from the viewpoint of the adhesive ability of the adhesive composition and the damp heat durability of the polarizer using polyvinyl alcohol-based polarizers, alkyl ester compounds of (meth)acrylate and C4-C4 compounds of (meth)acrylate with straight or branched chains are preferred. 36 Of the total 100% by mass of alkyl ester compounds, the content of (meth)acrylate cyclic alkyl ester compounds is preferably 30% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 80% by mass or less, further preferably 40% by mass or more and 75% by mass or less, and even more preferably 50% by mass or more and 70% by mass or less.

[0098] When the total amount of the adhesive composition is set to 100% by mass, the content of (meth)acrylate compound (C) is generally 15% by mass or more and 75% by mass or less. From the viewpoint of the adhesive composition's ability to bond to thermoplastic resin films (or layers), it is preferably 15% by mass or more and 70% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

[0099] [4] Photopolymerization initiator (D)

[0100] There are no particular limitations on photopolymerization initiators (D), as long as they are compounds that can generate active free radicals, acids, etc. through the action of light and initiate the polymerization of (meth)acrylate compounds (C).

[0101] The adhesive composition may contain only one photopolymerization initiator (D) or two or more.

[0102] As a photopolymerization initiator (D), there are no particular limitations, and examples include oxime compounds such as O-acyl oxime compounds, alkyl phenyl ketone compounds, and acylphosphine oxide compounds.

[0103] O-acyloxime compounds are compounds having the structure shown in formula (d) below. Hereinafter, * denotes a bond.

[0104] [Chemical Formula 3]

[0105]

[0106] Examples of O-acyl oxime compounds include N-benzoyloxy-1-(4-phenylthiophenyl)butane-1-one-2-imine, N-benzoyloxy-1-(4-phenylthiophenyl)octane-1-one-2-imine, N-benzoyloxy-1-(4-phenylthiophenyl)-3-cyclopentylpropane-1-one-2-imine, N-acetoxy-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethane-1-imine, and N-acetoxy-1-[9-ethyl-6-{2-methyl-4-(3,3-dimethyl-2,4-dioxane-2,4-dioxane-3-yl]-9H-carbazole-3-yl]ethane-1-imine. Examples of imines include: [9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-3-cyclopentylpropane-1-imine, [9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-3-cyclopentylpropane-1-one-2-imine, [4-(2-hydroxyethoxy)phenylthiophenyl]propane-1-one-2-imine, and [4-(1-methyl-2-methoxyethoxy)-2-methylphenyl]-1-(9-ethyl-6-nitro-9H-carbazole-3-yl)methane-1-imine, etc.

[0107] You can also use commercially available products such as Irgacure (product name) OXE01, Irgacure OXE02, Irgacure OXE03 (all manufactured by BASF), N-1919, NCI-930, and NCI-831 (all manufactured by ADEKA).

[0108] Alkyl phenyl ketone compounds are compounds having a partial structure as shown in formula (d4) or a partial structure as shown in formula (d5). In these partial structures, the benzene ring may have substituents.

[0109] [Chemical Formula 4]

[0110]

[0111] Examples of compounds having the structure shown in formula (d4) include 2-methyl-2-morpholino-1-(4-methylthioalkylphenyl)propane-1-one, 2-dimethylamino-1-(4-morpholinophenyl)-2-benzylbutane-1-one, and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]butane-1-one.

[0112] You can also use commercially available products such as Omnirad 369, Omnirad 907, and Omnirad 379 (all manufactured by IGM Resins B.V.).

[0113] Examples of compounds having the structure shown in formula (d5) include oligomers of 2-hydroxy-2-methyl-1-phenylpropane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-(4-isopropenylphenyl)propane-1-one, α,α-diethoxyacetophenone, and benzoyladimethyl ketal.

[0114] Alternatively, commercially available products such as Omnirad 184 (manufactured by IGM Resins BV) can be used.

[0115] Examples of acylphosphine oxide compounds include phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (e.g., trade name "Omnirad 819" (manufactured by IGM Resins BV)) and 2,4,6-trimethylbenzoyl diphenylphosphine oxide.

[0116] Further examples of photopolymerization initiators (D) can be cited as follows:

[0117] Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and other benzoin compounds;

[0118] Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4,4'-di(N,N'-dimethylamino)-benzophenone and other benzophenone compounds;

[0119] 2-Isopropylthioxanthone, 2,4-diethylthioxanthone, and other xanthone compounds;

[0120] Anthracene compounds such as 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 2-ethyl-9,10-diethoxyanthracene;

[0121] Quinone compounds such as 9,10-phenanthroquinone, 2-ethylanthraquinone, and camphorquinone;

[0122] Benzoyl, methyl phenylglyoxylate, titanium ceramsite, etc.

[0123] When the total amount of the adhesive composition is set to 100% by mass, the content of photopolymerization initiator (D) is generally 0.1% by mass or more and 20% by mass or less. From the viewpoint of the curability of the adhesive composition and the adhesive composition's ability to bond to thermoplastic resin films (or layers), it is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less (e.g., 8% by mass or less).

[0124] When the total amount of (meth)acrylate compound (C) is set to 100 parts by mass, the content of photopolymerization initiator (D) is generally 0.1 parts by mass or more and 30 parts by mass or less. From the viewpoint of the curability of the adhesive composition and the adhesive composition's ability to bond to thermoplastic resin films (or layers), it is preferable to be 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.

[0125] [5] Tackifier

[0126] The adhesive composition may further include a tackifier. There are no particular limitations on the tackifying resin; it may be suitably selected from known tackifying resins, such as rosin derivatives (e.g., rosin, polymerized rosin, hydrogenated rosin), terpene resins (e.g., terpene resins, aromatic modified terpene resins, terpene phenol resins, hydrogenated terpene resins), petroleum resins, phenolic resins, xylene resins, etc.

[0127] The adhesive composition preferably further comprises petroleum resin (E). By further comprising petroleum resin (E) in the adhesive composition, the adhesion can be improved and the moisture permeability of the cured film formed by the adhesive composition can be reduced.

[0128] Adhesive compositions capable of forming a cured film with low moisture permeability are suitable for applications requiring suppression of moisture ingress or egress through the cured film. For example, in a polarizing plate or an image display panel containing a polarizing plate in which a thermoplastic resin film is laminated on at least one side by an adhesive layer, if the adhesive layer is low in moisture permeability, it is possible to suppress curling (warping) of the polarizing plate or image display panel caused by moisture ingress or egress.

[0129] The adhesive composition further includes petroleum resin (E), which is also advantageous in improving the adhesion between the polarizer and the thermoplastic resin film.

[0130] Examples of petroleum resins (E) include aromatic petroleum resins, aliphatic petroleum resins, cyclic aliphatic petroleum resins, aliphatic-aromatic petroleum resins, and coumarone-based resins. Additionally, resins obtained by hydrogenating these resins can also be cited.

[0131] Aromatic petroleum resins are resins containing one or more structural units derived from aromatic hydrocarbons. They can be resins obtained by hydrogenation of the resin or resins obtained by modification of the resin.

[0132] Aromatic petroleum resins are preferably C9-based petroleum resins. C9-based petroleum resins are resins obtained by copolymerizing C9 fractions, and can be resins obtained by hydrogenation of the resin or resins obtained by modification of the resin.

[0133] C9 series petroleum resins can also be obtained by copolymerizing the C9 fraction with other monomer components, or by hydrogenating the resin, or by modifying the resin. C5 fraction is an example of one of the other monomer components.

[0134] Examples of C9 fractions include petroleum fractions with approximately 8 to 10 carbon atoms, such as styrene, alkylstyrene, vinyltoluene, 1-methyl-1-phenylethylene, indene, and methylindene.

[0135] Examples of C5 fractions include petroleum fractions with approximately 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, isoprene, and isoprene (Japanese: ピペリレン).

[0136] Furthermore, the petroleum resin (E) can be a C5-based petroleum resin obtained by copolymerizing the aforementioned C5 fraction, a resin obtained by hydrogenating the C5-based petroleum resin, or a resin obtained by modifying the resin. Alternatively, it can be an alicyclic hydrocarbon resin obtained by polymerizing the C5 fraction after cyclization dimerization. Examples of alicyclic hydrocarbon resins include polymers containing structural units derived from dicyclopentadiene.

[0137] The weight-average molecular weight of the petroleum resin (E) is typically 500 or more and 10,000 or less. From the viewpoint of reducing the moisture permeability of the cured film formed by the adhesive composition and the adhesive composition's ability to bond to the 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 even more preferably 600 or more and 3,000 or less.

[0138] The weight-average molecular weight of petroleum resin (E) can be determined as a GPC-based conversion value for standard polystyrene.

[0139] When the adhesive composition contains petroleum resin (E), and the total amount of the adhesive composition is set to 100% by mass, from the viewpoint of reducing the moisture permeability of the cured film formed by the adhesive composition, and from the viewpoint of the adhesive composition's ability to bond to the thermoplastic resin film (or layer), and especially from the viewpoint of improving the adhesion between the polyvinyl alcohol polarizer and the thermoplastic resin film when using a polyvinyl alcohol polarizer as the polarizer, the content of 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.

[0140] The cured film formed from the adhesive composition preferably has low moisture permeability. For a cured film with a thickness of 10 μm containing the adhesive composition, the moisture permeability measured using the cup method specified in JIS Z 0208 at a temperature of 40°C and a relative humidity of 90% is preferably 400 g / (m²). 2 • 24hr or less, more preferably 300g / (m 2 • 24hr or less, more preferably 200g / (m 2 • Below 24hr. The permeability is typically 1 g / (m³). 2 • 24hr or more, for example, 5g / (m 2 ·24hr) or more.

[0141] The permeability J of a cured film containing an adhesive composition can be specifically determined as follows: a laminate is prepared by forming the cured film on a substrate film with known permeability, the permeability of the laminate is measured using the method described above, and the result is determined based on the following formula.

[0142] 1 / Jt=(1 / J)+(1 / Jsub)

[0143] In the above formula, Jt represents the moisture permeability of the laminate, and Jsub represents the moisture permeability of the substrate film. The same substrate film as the thermoplastic resin film described later can be used. When measuring the moisture permeability of the laminate according to JIS Z 0208, the laminate is mounted in a cup with the cured film facing outwards.

[0144] Regarding the aforementioned laminate, when using, for example, a 60 μm thick (meth)acrylic resin film as the substrate film, the preferred moisture permeability of the laminate of this (meth)acrylic resin film and a 10 μm thick cured film containing an adhesive composition, measured using the cup method specified in JIS Z0208 at a temperature of 40°C and a relative humidity of 90%, is 55 g / (m²). 2 • 24hr or less, more preferably 50g / (m 2 • Below 24hr. The permeability is typically 1 g / (m³). 2• 24hr or more, for example, 5g / (m 2 ·24hr) or more.

[0145] [6] Other ingredients

[0146] The adhesive composition may contain other components besides those mentioned above.

[0147] Other components include curing agents other than (meth)acrylate compounds (C), crosslinking agents, coupling agents, antioxidants, UV absorbers, heat stabilizers, and other additives.

[0148] [7] Viscosity of the adhesive composition

[0149] 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.

[0150] The viscosity of the adhesive composition at 25°C can be measured using an E-type viscometer.

[0151] <Polarizing plate>

[0152] 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.

[0153] 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.

[0154] 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.

[0155] The polarizing plate of the present invention can be used in image display devices such as liquid crystal display devices and organic EL devices.

[0156] [1] Structure of polarizing plate

[0157] An example of the layer structure of the polarizing plate of the present invention is shown below. Figure 1 and Figure 2 .

[0158] like Figure 1 As shown, the polarizing plate of the present invention may sequentially include a polarizing sheet 30, a first adhesive layer 15 and a first thermoplastic resin film 10, that is, it may include a polarizing sheet 30 and a first thermoplastic resin film 10 laminated on one side of the polarizing sheet by means of the first adhesive layer 15.

[0159] The first adhesive layer 15 is preferably in direct contact with the first thermoplastic resin film 10.

[0160] The polarizer 30 is preferably in direct contact with the first adhesive layer 15.

[0161] Alternatively, it can be like Figure 2 As shown, the polarizing plate of the present invention includes a polarizing film 30, a first thermoplastic resin film 10 laminated on one side by a first adhesive layer 15, and a second thermoplastic resin film 20 laminated on the other side of the polarizing film 30 by a second adhesive layer 25.

[0162] The first adhesive layer 15 is preferably in direct contact with the first thermoplastic resin film 10.

[0163] The polarizer 30 is preferably in direct contact with the first adhesive layer 15.

[0164] The second adhesive layer 25 is preferably in direct contact with the second thermoplastic resin film 20.

[0165] The polarizer 30 is preferably in direct contact with the second adhesive layer 25.

[0166] When the polarizing plate has a first adhesive layer 15 and a second adhesive layer 25, either one can be formed by the adhesive composition of the present invention, or both adhesive layers can be formed by the adhesive composition of the present invention. The adhesive layer formed by the adhesive composition of the present invention is preferably the adhesive layer on the observation side (the adhesive layer away from the adhesive layer described later).

[0167] When two adhesive layers are formed by the adhesive composition of the present invention, these adhesive compositions may have the same composition or different compositions.

[0168] Not limited to Figure 1 and Figure 2For example, the polarizing plate of the present invention may include other layers (or films) besides those described above. Examples of other layers include, for instance, an adhesive layer laminated on the outer surfaces of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizer 30; a release film (also called a "release film") laminated on the outer surface of the adhesive layer; a protective film (also called a "surface protection film") laminated on the outer surfaces of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizer 30; and an optically functional film (or layer) laminated on the outer surfaces of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and / or the polarizer 30 by means of an adhesive layer and an adhesive layer, etc.

[0169] [2] Polarizing plate

[0170] Polarizer 30 is a film that selectively transmits linearly polarized light in a certain direction from natural light. Examples of polarizers 30 include iodine-based polarizers formed by adsorbing iodine (a dichroic pigment) onto a polyvinyl alcohol-based resin film and orienting it; dye-based polarizers formed by adsorbing dichroic dyes (dichroic pigments) onto a polyvinyl alcohol-based resin film and orienting them; and coated polarizers obtained by coating a dichroic dye in a lyotropic liquid crystal state, orienting and immobilizing it. These polarizers are called absorption-type polarizers because they selectively transmit linearly polarized light in one direction from natural light and absorb linearly polarized light in another direction.

[0171] The polarizer 30 is not limited to an absorptive polarizer. It can also be a reflective polarizer that selectively transmits linearly polarized light in one direction from natural light, reflects linearly polarized light in another direction, or scatters linearly polarized light in another direction. However, from the perspective of superior visual performance when the polarizer is applied to image display devices, etc., an absorptive polarizer is preferred.

[0172] The polarizer 30 is more preferably a polyvinyl alcohol polarizer made of polyvinyl alcohol resin, and even more preferably a polyvinyl alcohol polarizer obtained by adsorbing iodine, dichroic dyes and other dichroic pigments into a polyvinyl alcohol resin film and causing it to oriented. It is particularly preferably a polyvinyl alcohol polarizer obtained by adsorbing iodine into a polyvinyl alcohol resin film and causing it to oriented.

[0173] Polyvinyl alcohol polarizers can be manufactured using polyvinyl alcohol resin films (or layers) through conventionally known methods.

[0174] The thickness of the polarizer 30 can be set to 30 μm or less, preferably 25 μm or less (for example, preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and still more preferably 8 μm or less). The thickness of the polarizer 30 is usually 2 μm or more. Reducing the thickness of the polarizer 30 is beneficial for the thinning of the polarizer plate and, consequently, the image display device using the polarizer plate.

[0175] [3] Thermoplastic resin film

[0176] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can each be a film containing a light-transmitting (preferably optically transparent) thermoplastic resin, such as a polyolefin resin containing chain polyolefin resins (polyethylene resin, polypropylene resin, etc.), cyclic polyolefin resins (norbornene resin, etc.); cellulose ester resins such as triacetylcellulose and diacetylcellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins; or mixtures or copolymers thereof.

[0177] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be either unstretched films or films that have undergone uniaxial or biaxial stretching. Biaxial stretching can be simultaneous biaxial stretching in two stretching directions, or it can be sequential biaxial stretching where the film is stretched in the first direction and then stretched in a second direction different from it.

[0178] The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can be protective films that serve to protect the polarizer 30, or protective films with optical functions such as phase difference films.

[0179] For example, by stretching a film containing the aforementioned thermoplastic resin (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer on the thermoplastic resin film, a phase difference film with arbitrary phase difference values ​​can be produced.

[0180] (Meth)acrylic resins can be, for example, polymers containing 50% or more by mass of methacrylate as the main monomer, preferably copolymers obtained by copolymerizing methacrylate with other copolymers.

[0181] In one embodiment, the (meth)acrylic resin contains methyl methacrylate as a copolymer component, or contains methyl methacrylate and methyl acrylate as copolymer components.

[0182] Other copolymer components besides methyl methacrylate include, for example, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate or tert-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and other methacrylates other than methyl methacrylate.

[0183] Acrylates such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate or tert-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate;

[0184] Hydroxyalkyl acrylates such as methyl 2-(hydroxymethyl)acrylate, methyl 2-(1-hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, n-butyl 2-(hydroxymethyl)acrylate, isobutyl acrylate or tert-butyl acrylate;

[0185] Unsaturated acids such as methacrylic acid and acrylic acid;

[0186] Halogenated styrene derivatives such as chlorostyrene and bromostyrene;

[0187] Vinyltoluene, α-methylstyrene, and other substituted styrene derivatives;

[0188] Unsaturated nitriles such as acrylonitrile and methacrylonitrile;

[0189] Unsaturated anhydrides such as maleic anhydride and citrate anhydride;

[0190] Unsaturated imides such as phenylmaleimide and cyclohexylmaleimide; and monofunctional monomers.

[0191] The other monofunctional monomers mentioned above can be used alone or in combination of two or more.

[0192] Multifunctional monomers can be used as other copolymer components mentioned above.

[0193] Examples of multifunctional monomers include 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, tetradecaethylene glycol di(meth)acrylate, and tetradecaethylene glycol di(meth)acrylate, which are compounds formed by esterifying two terminal hydroxyl groups of ethylene glycol or its oligomers with (meth)acrylate.

[0194] A compound formed by esterification of two terminal hydroxyl groups of propylene glycol or its oligomers with (meth)acrylic acid;

[0195] Neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, butanediol di(meth)acrylate, etc. are compounds formed by esterifying the hydroxyl groups of diols with (meth)acrylic acid;

[0196] A compound formed by esterification of two terminal hydroxyl groups of bisphenol A, bisphenol A alkyl oxide adducts, or their halogenated derivatives with (meth)acrylic acid;

[0197] Compounds obtained by esterification of polyols such as trimethylolpropane and pentaerythritol with (meth)acrylic acid, and compounds obtained by ring-opening addition of glycidyl methacrylate to their terminal hydroxyl groups;

[0198] Compounds formed by ring-opening addition of glycidyl (meth)acrylate to dicarboxylic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, their halogenated derivatives, or their alkyl oxide adducts;

[0199] Aryl methacrylates; aromatic divinyl compounds such as divinylbenzene; etc.

[0200] Ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferred materials.

[0201] (Meth)acrylic resins can be resins modified by reactions between functional groups present in the copolymer. Examples of such reactions include, for instance, the intramolecular demethanolization condensation reaction of the methyl group of (meth)acrylate with the hydroxyl group of 2-(hydroxymeth)acrylate, and the intramolecular dehydration condensation reaction of the carboxyl group of (meth)acrylic acid with the hydroxyl group of 2-(hydroxymeth)acrylate.

[0202] The glass transition temperature of (meth)acrylic resins is preferably above 80°C and below 160°C. The glass transition temperature can be controlled by adjusting the polymerization ratio of methacrylate monomers to acrylate monomers, the carbon chain length of their respective ester groups and the types of functional groups they possess, as well as the polymerization ratio of polyfunctional monomers to all monomers.

[0203] Introducing ring structures into the polymer backbone is also an effective method for increasing the glass transition temperature of (meth)acrylic resins. The ring structures are preferably heterocyclic structures such as cyclic anhydride structures, cyclic imide structures, and lactone structures. Specifically, examples include cyclic anhydride structures such as glutaric anhydride and succinic anhydride; cyclic imide structures such as glutarimide and succinimidide; and lactone ring structures such as butyrolactone and valerolactone.

[0204] The higher the content of ring structures in the main chain, the greater the tendency to increase the glass transition temperature of (meth)acrylic resins.

[0205] Cyclic anhydride structures and cyclic imide structures can be introduced by the following methods: by copolymerizing monomers with cyclic structures such as maleic anhydride and maleimide; by introducing cyclic anhydride structures through dehydration and demethanolification condensation reactions after polymerization; and by reacting amino compounds to introduce cyclic imide structures.

[0206] Resins (polymers) with lactone ring structures can be obtained by the following method: after preparing a polymer with hydroxyl and ester groups in the polymer chain, the hydroxyl and ester groups in the obtained polymer are cyclized and condensed by heating in the presence of a catalyst such as an organophosphorus compound, as needed, to form a lactone ring structure.

[0207] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may contain additives as needed. Examples of additives include lubricants, anti-blocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact resistance modifiers, and surfactants.

[0208] From the perspective of membrane-forming properties and impact resistance, (meth)acrylic resins can contain acrylic rubber particles as impact modifiers. Acrylic rubber particles refer to particles in which an elastic polymer based on acrylate is a necessary component. Examples of acrylic rubber particles include single-layer particles that are essentially formed solely by the elastic polymer, and multilayer particles in which the elastic polymer is one layer.

[0209] As an example of the aforementioned elastic polymer, a crosslinked elastic copolymer can be obtained by copolymerizing alkyl acrylate as the main component and other vinyl monomers and crosslinking monomers that can copolymerize with it.

[0210] Alkyl acrylates, which are the main components of elastic polymers, include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc., in which the alkyl group has about 1 to 8 carbon atoms. Alkyl acrylates with 4 or more carbon atoms are preferred.

[0211] Other vinyl monomers that can copolymerize with the aforementioned alkyl acrylates include compounds having a polymerizable carbon-carbon double bond in the molecule; more specifically, methacrylates such as methyl methacrylate; aromatic vinyl compounds such as styrene; and vinyl cyanide compounds such as acrylonitrile.

[0212] Examples of crosslinking monomers include compounds that have at least two polymerizable carbon-carbon double bonds within the molecule. More specifically, examples include (meth)acrylates of polyols such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate; alkenyl esters of (meth)acrylates such as allyl (meth)acrylate; and divinylbenzene.

[0213] At least one of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is preferably a film containing (meth)acrylic resin ((meth)acrylic resin film), which is preferably laminated to the polarizer 30 by means of an adhesive layer formed by the adhesive composition of the present invention.

[0214] The adhesive composition of the present invention exhibits particularly good adhesion when the thermoplastic resin film is a (meth)acrylic resin film. Therefore, the adhesive composition of the present invention is suitable for bonding polarizers to (meth)acrylic resin films.

[0215] (Meth)acrylic resin films preferably contain (meth)acrylic resins in their resin composition.

[0216] The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be films made of the same thermoplastic resin or films made of different thermoplastic resins. The first thermoplastic resin film 10 and the second thermoplastic resin film 20 can be the same or different in terms of thickness, presence or absence of additives, their types, phase difference characteristics, etc.

[0217] 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 resin film (preferably a cyclic polyolefin resin film), a cellulose ester resin, or a polyester resin film.

[0218] In another embodiment, the first thermoplastic resin film 10 and the second thermoplastic resin film 20 are (meth)acrylic resin films.

[0219] The first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 may have surface treatment layers (coatings) such as a hard coating layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an antistatic layer, an anti-fouling layer, and a conductive layer on their outer surface (the surface opposite to the polarizer 30).

[0220] 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.

[0221] 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.

[0222] [4] Manufacturing of polarizing plate and adhesive layer

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] 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.

[0228] Other adhesive compositions include conventionally known water-based adhesives or active energy radiation-cured adhesives.

[0229] Examples of water-based adhesives include conventionally known adhesive compositions that use polyvinyl alcohol resins or urethane resins as the main component.

[0230] Reactive energy radiation-cured adhesives are adhesives that are cured by irradiation with reactive energy rays such as ultraviolet light, visible light, electron beams, and X-rays. When using reactive energy radiation-cured adhesives, the adhesive layer on the polarizing plate is the cured layer of that adhesive.

[0231] The active energy radiation-curable adhesive can be an adhesive containing an epoxy compound that cures via cationic polymerization as a curing component, preferably an ultraviolet-curable adhesive containing such an epoxy compound as a curing component. An epoxy compound refers to a compound having an average of one or more, preferably two or more, epoxy groups within its molecule. Only one epoxy compound may be used, or two or more may be used in combination.

[0232] Examples of epoxy compounds include hydrogenated epoxy compounds (glycidyl ethers of polyols having alicyclic rings) obtained by reacting epichlorohydrin with an alicyclic polyol to obtain alicyclic polyols; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyols or their alkyl oxide adducts; and alicyclic epoxy compounds that have one or more epoxy groups bonded to alicyclic rings within the molecule.

[0233] In active energy radiation-curable adhesives, the curing component can replace the aforementioned epoxy compounds or contain free radical polymerizable (meth)acrylic acid compounds together with them. Examples of (meth)acrylic acid compounds include (meth)acrylic acid ester monomers having one or more (meth)acryloyloxy groups within the molecule; (meth)acrylic acid ester oligomers having at least two (meth)acryloyloxy groups within the molecule, obtained by reacting two or more compounds containing functional groups; and other compounds containing (meth)acryloyloxy groups.

[0234] In the case where the active energy ray-curable adhesive contains an epoxy compound that is cured by cationic polymerization as a curing component, it is preferable to contain a photocationic polymerization initiator. Examples of photocationic polymerization initiators include aromatic diazonium salts; aromatic iodonium salts, aromatic sulfonium salts, and other sulfonium salts; iron-aromatic complexes, etc.

[0235] In the case of active energy radiation-curable adhesives containing free radical polymerizable components such as (meth)acrylic acid compounds, it is preferable to contain a photoradical polymerization initiator. Examples of photoradical polymerization initiators include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthones, fluorenones, camphorquinone, benzaldehyde, and anthraquinones.

[0236] The bonding of the polarizer 30 to the thermoplastic resin film may include the following steps: applying an adhesive composition to the bonding surface of the polarizer 30 and / or the bonding surface of the thermoplastic resin film, or injecting an adhesive composition between the polarizer 30 and the thermoplastic resin film, and bonding the two films by overlapping the layers of the adhesive composition, for example by pressing from above and below using a bonding roller.

[0237] The adhesive composition layer can be formed using various coating methods, such as doctor blades, wire bars, die coaters, comma coaters, and gravure coaters. Alternatively, the adhesive composition can be cast between the polarizer 30 and the thermoplastic resin film, with their bonding surfaces facing inwards.

[0238] Before applying the adhesive composition, one or both of the bonding surfaces of the polarizer 30 and the thermoplastic resin film can be subjected to easy-bonding treatments (surface activation treatments) such as saponification, corona discharge, plasma treatment, flame treatment, primer treatment, and anchor coating.

[0239] In the case of using an active energy ray curable adhesive, the adhesive composition layer is cured by irradiating it with active energy rays.

[0240] Light sources used for irradiating active energy rays can be any source capable of producing ultraviolet rays, electron beams, X-rays, etc. Light sources with luminous distribution at wavelengths below 400nm are particularly suitable, such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0241] The thickness of the adhesive layer formed by the adhesive composition of the present invention in the polarizing plate is, for example, 0.1 μm or more and 100 μm or less, preferably 0.5 μm or more and 80 μm or less, more preferably 1 μm or more and 60 μm or less, and even more preferably 2 μm or more and 50 μm or less. From the viewpoint of making the polarizing plate thinner, it is also preferable to set the thickness of the adhesive layer to 30 μm or less, and even more preferably 20 μm or less.

[0242] The thicknesses of the first adhesive layer 15 and the second adhesive layer 25 can be the same or different.

[0243] [5] Other constituent elements of the polarizing plate

[0244] [5-1] Optical functional films

[0245] 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.

[0246] 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.

[0247] 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.

[0248] The substrate film is typically a film containing a thermoplastic resin, an example of which is a cellulose ester resin such as triacetyl cellulose.

[0249] 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.

[0250] 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.

[0251] [5-2] Adhesive layer

[0252] 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.

[0253] 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.

[0254] The thickness of the adhesive layer is determined based on its adhesive strength, etc., and a range of 1 μm or more and 50 μm or less is appropriate, preferably 2 μm or more and 40 μm or less.

[0255] The polarizing plate may include a release film laminated on the outer surface of the adhesive layer. The release film may be a film containing polyethylene resins such as polyethylene, polypropylene resins such as polypropylene, polyester resins such as polyethylene terephthalate, etc. Among them, a stretch film of polyethylene terephthalate is preferred.

[0256] The adhesive layer may contain glass fibers, glass beads, resin beads, fillers containing metal powder or other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, etc., as needed.

[0257] [5-3] Protective film

[0258] The polarizing plate of the present invention may include a protective film for protecting its surface (the surface of the thermoplastic resin film, the surface of the polarizer, etc.). The protective film, for example, is peeled off together with its adhesive layer after the polarizing plate is attached to an image display element or other optical component.

[0259] The protective film, for example, consists of a substrate film and an adhesive layer laminated thereon. Regarding the adhesive layer, refer to the description above.

[0260] The resin constituting the substrate 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, or a thermoplastic resin such as polycarbonate. Polyester-based resins such as polyethylene terephthalate are preferred.

[0261] Example

[0262] The present invention is illustrated below with examples, but the invention is not limited to these examples. In the examples, percentages and parts representing the content or amount used are mass references unless otherwise specified. The thickness of the film and adhesive layer (cured film) was measured using a digital micrometer “MH-15M” manufactured by Nikon Corporation.

[0263] <Example 1>

[0264] (1) Preparation of curing adhesive composition

[0265] Mix the components shown in Table 1 at the proportions shown in Table 1 to prepare curable adhesive composition A. The proportions of each component shown in Table 1 are in parts by mass.

[0266] The details of each component shown in Table 1 are as follows.

[0267] (A): Maleic anhydride modified liquid polybutadiene (trade name "Lithene ultraN4-B-10MA" manufactured by Synthomer, number average molecular weight: 8200, viscosity at 25°C: 60~90Pa·sec, acid value: 54KOHmg / g)

[0268] (Ba): Unmodified liquid polybutene (trade name "Nippon Yu Co., Ltd.", number average molecular weight: 370)

[0269] (Bb): Unmodified liquid polybutene (trade name "Nichiyu Polybutene·EMAWET015N" manufactured by Nichiyu Corporation, number average molecular weight: 580)

[0270] (C-1a): Dicyclopentyl acrylate (trade name "FA-513AS" manufactured by Hitachi Chemical Co., Ltd.)

[0271] (C-1b): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0272] (C-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., EO 10 mol)

[0273] (D): Phenylene bis(2,4,6-trimethylbenzoyl)phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins BV)

[0274] (E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Co., Ltd., hydrogenated resin (alicyclic saturated hydrocarbon resin with dicyclopentadiene as monomer component), softening point (nominal value): 104.5℃, weight average molecular weight (nominal value): 610)

[0275] (2) Fabrication of polarizing plates

[0276] A 60 μm thick polymethyl methacrylate (PMMA) film was subjected to corona treatment. The curable adhesive composition A prepared in (1) above was then applied to the corona-treated surface using an adhesive coating device. The resulting coating layer was then laminated with a 23 μm thick polyvinyl alcohol-iodine polarizer using a clamping roller to obtain a polarizer with a PMMA film.

[0277] Next, a 50 μm thick phase retardation film (trade name "ZEONOR" manufactured by ZEON Corporation of Japan) containing a cyclic polyolefin resin was subjected to corona treatment. A curable adhesive composition B prepared as described below was then applied to the corona-treated surface using an adhesive coating apparatus. A laminate was obtained by stacking the resulting coating layer with the polarizer surface of a polarizer containing a PMMA film using a clamping roller. The total cumulative light intensity (cumulative amount of light irradiation intensity in the wavelength region of 320–400 nm) irradiated from the phase retardation film side of the laminate was approximately 200 mJ / cm². 2 A polarizing plate was fabricated by curing layers of both adhesive composition B and adhesive composition A under ultraviolet (UVB) light (measurement device: based on the UV Power Puck II manufactured by FusionUV). It should be noted that the thickness of the cured layer of adhesive composition A is approximately 10 μm, and the thickness of the cured layer of adhesive composition B is 2.5 μm.

[0278] The curable adhesive composition B was prepared by mixing 100 parts by weight of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylic acid (trade name "Celloxide2021P" manufactured by Daicel Co., Ltd.) with 25 parts by weight of 1,4-butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Co., Ltd.) and 5.6 parts by weight of photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., Ltd.).

[0279] <Examples 2-9, Comparative Example 1>

[0280] As shown in Table 1, the proportions of the compounding components were changed, and otherwise the same procedure was followed as in Example 1 to prepare a curable adhesive composition A. Furthermore, using this curable adhesive composition A, a polarizing plate was fabricated in the same manner as in Example 1, except that...

[0281] <Measurement and Evaluation>

[0282] (1) Moisture permeability of the cured film formed by the curing adhesive composition A

[0283] Curing adhesive composition A was applied to a 60 μm thick PMMA film that had undergone corona treatment using an adhesive application apparatus.

[0284] Untreated polyethylene terephthalate (PET) film is laminated onto a coating layer of curable adhesive composition A, and bonding is performed using clamping rollers. Next, the film is irradiated with a total cumulative light intensity (cumulative amount of light irradiation intensity in the wavelength region of 320–400 nm) of approximately 200 mJ / cm².2 (Measurement apparatus: based on measurements from the UV Power Puck II manufactured by FusionUV Corporation) Ultraviolet (UVB) light cured the adhesive layer, resulting in a laminate consisting of a PMMA film, a cured adhesive layer, and a PET film. Then, the PET film was peeled off, yielding a laminate consisting of a PMMA film and a cured adhesive layer (cured film) (sample for moisture permeability measurement).

[0285] For the obtained laminate (sample for moisture permeability measurement), the moisture permeability [g / (m³)] at a temperature of 40℃ and a relative humidity of 90% was measured using the cup method specified in JIS Z 0208. 2 • 24hr). It should be noted that during the measurement, the cured adhesive layer (cured film) in the above-mentioned laminate was placed in an environment with a temperature of 40°C and a relative humidity of 90%. In addition, the laminate was mounted on the cup with the cured film facing outwards.

[0286] The results are shown in the "Water Permeability of Laminates" column of Table 1. The values ​​in parentheses represent the thickness of the cured film in the laminate (unit: μm).

[0287] In addition, using the moisture permeability (Jt) of the obtained laminate, the moisture permeability (J) of the cured film itself at a temperature of 40°C and a relative humidity of 90% is calculated based on the following formula.

[0288] 1 / Jt=(1 / J)+(1 / Jsub)

[0289] A 60 μm thick PMMA film used as the substrate membrane, measured using the cup method specified in JIS Z 0208 at 40°C and 90% relative humidity, had a water permeability (Jsub) of 70 g / (m²). 2 •24hr).

[0290] The results are shown in the "Water Permeability of Cured Film" column of Table 1. The values ​​in parentheses represent the thickness of the cured film (unit: μm).

[0291] (2) Evaluation of the adhesion between the polarizer and the PMMA film in the polarizing plate (initial)

[0292] An adhesive layer is formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with adhesive layer is cut into a length (parallel to the absorption axis of the polarizer) of 200 mm × width of 25 mm, and the adhesive layer is bonded to a glass plate to obtain a laminate. The obtained laminate is used as a test piece for determining the peel strength between the polarizer and the PMMA film. A cutting tool is placed between the polarizer and the PMMA film of the test piece, and a 30 mm peel is made from the end along the length direction. The peeled portion is clamped by the clamping part of the testing machine, and the glass plate is clamped by the lower clamping part. For the test piece in this state, a peel test is performed in an atmosphere with a temperature of 23°C and a relative humidity of 55%, according to JIS K 6854-2:1999 "Adhesives - Peel strength test method - Part 2: 180-degree peel", at a clamping movement speed of 300 mm / min. The average peel force over a length of 170 mm excluding the 30 mm clamping portion is determined and taken as the peel strength between the polarizer and the PMMA film. The results are shown in Table 1. Peel strength was measured after the polarizing plate was fabricated and placed in an environment of 23°C and 50% RH for 24 hours.

[0293] In Table 1, "fracture" refers to a condition where the peel strength is very high, and the PMMA film or polarizer breaks before the film is peeled off. In Comparative Example 1, the adhesion between the polarizer and the PMMA film was too weak to determine the peel strength.

[0294] (3) Evaluation of the adhesion between the polarizer and the PMMA film in the polarizing plate (after exposure to high temperature and high humidity environment)

[0295] An adhesive layer is formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with adhesive layer is cut into a size of 200 mm in length (parallel to the absorption axis of the polarizer) × 25 mm in width, and the adhesive layer is bonded to the glass to obtain a laminate. The obtained laminate is placed in a high temperature and high humidity environment of 80°C and 90% RH for 24 hours, and then placed in an environment of 23°C and 50% RH for 24 hours. Then, a cutting tool of a cutting machine is placed between the polarizer and the PMMA film of the obtained laminate, and 30 mm is peeled off from the end along the length direction. The peeled part is clamped by the clamping part of the testing machine, and the glass plate is clamped by the lower clamping part. For the test piece in this condition, a peel test was conducted in an atmosphere of 23°C and 55% relative humidity, according to JIS K 6854-2:1999 "Adhesives - Test method for peel strength - Part 2: 180-degree peel", with a clamping and moving speed of 300 mm / min. The average peel force over a length of 170 mm excluding the 30 mm clamping portion was determined and taken as the peel strength between the polarizer and the PMMA film. The results are shown in Table 1.

[0296] [Table 1]

[0297]

[0298] <Example 10>

[0299] (1) Preparation of curing adhesive composition

[0300] Mix the components shown in Table 2 at the proportions shown in Table 2 to prepare curable adhesive composition C. The proportions of each component shown in Table 2 are in parts by mass.

[0301] The details of each component shown in Table 2 are as follows.

[0302] (Ab): Maleic anhydride modified liquid polybutadiene (trade name "Lithene ultraN4-5000-10MA" manufactured by Synthomer, number average molecular weight: 5500, viscosity at 25℃: 25~60Pa·sec, acid value: 54KOHmg / g)

[0303] (Bb): Unmodified liquid polybutene (trade name "Nichiyu Polybutene·EMAWET015N" manufactured by Nichiyu Corporation, number average molecular weight: 580)

[0304] (C-1a): Dicyclopentyl acrylate (trade name "FA-513AS" manufactured by Hitachi Chemical Co., Ltd.)

[0305] (C-1b): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0306] (C-1c): Stearyl acrylate (trade name "AS" manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0307] (C-1d): Lauryl acrylate (trade name "LA" manufactured by Osaka Organic Chemicals Co., Ltd.)

[0308] (C-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., EO 10 mol)

[0309] (D): Phenylene bis(2,4,6-trimethylbenzoyl)phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins BV)

[0310] (E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Co., Ltd., hydrogenated resin (alicyclic saturated hydrocarbon resin with dicyclopentadiene as monomer component), softening point (nominal value): 104.5℃, weight average molecular weight (nominal value): 610)

[0311] (2) Fabrication of polarizing plates

[0312] A 60 μm thick polymethyl methacrylate (PMMA) film was subjected to corona treatment. The curable adhesive composition C prepared in (1) above was then applied to the corona-treated surface using an adhesive coating device. The resulting coating layer was then laminated with a 23 μm thick polyvinyl alcohol-iodine polarizer using a clamping roller to obtain a polarizer with a PMMA film.

[0313] Next, a 50 μm thick phase retardation film (trade name "ZEONOR" manufactured by ZEON Corporation of Japan) containing a cyclic polyolefin resin was subjected to corona treatment. A curable adhesive composition B prepared as described below was then applied to the corona-treated surface using an adhesive coating apparatus. A laminate was obtained by stacking the resulting coating layer with the polarizer surface of a polarizer containing a PMMA film using a clamping roller. The total cumulative light intensity (cumulative amount of light irradiation intensity in the wavelength region of 320–400 nm) irradiated from the phase retardation film side of the laminate was approximately 200 mJ / cm². 2 A polarizing plate was fabricated by curing layers of curable adhesive composition B and curable adhesive composition C under ultraviolet (UVB) light (measurement device: based on the UV Power Puck II manufactured by FusionUV). It should be noted that the thickness of the cured layer of curable adhesive composition C is approximately 10 μm, and the thickness of the cured layer of curable adhesive composition B is 2.5 μm.

[0314] The curable adhesive composition B was prepared by mixing 100 parts by weight of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylic acid (trade name "Celloxide2021P" manufactured by Daicel Co., Ltd.) with 25 parts by weight of 1,4-butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Co., Ltd.) and 5.6 parts by weight of photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., Ltd.).

[0315] <Examples 11-12, Comparative Examples 2-3>

[0316] The curable adhesive composition C was prepared by varying the amounts of the compounding components as shown in Table 2, except that the procedure was the same as in Example 10. Furthermore, a polarizing plate was fabricated using this curable adhesive composition C, except that the procedure was the same as in Example 10.

[0317] <Measurement and Evaluation>

[0318] (1) Moisture permeability of the cured film formed by the curing adhesive composition C

[0319] A curable adhesive composition C was applied to a 60 μm thick PMMA film that had undergone corona treatment.

[0320] Untreated polyethylene terephthalate (PET) film is laminated onto a coating layer of curable adhesive composition C, and bonding is performed using clamping rollers. Next, the film is irradiated with a total cumulative light intensity (the cumulative amount of light irradiation intensity in the wavelength region of 320–400 nm) of approximately 200 mJ / cm². 2 (Measurement apparatus: based on measurements from the UV Power Puck II manufactured by FusionUV Corporation) Ultraviolet (UVB) light cured the adhesive layer, resulting in a laminate consisting of a PMMA film, a cured adhesive layer, and a PET film. Then, the PET film was peeled off, yielding a laminate consisting of a PMMA film and a cured adhesive layer (cured film) (sample for moisture permeability measurement).

[0321] For the obtained laminate (sample for moisture permeability measurement), the moisture permeability [g / (m³)] at a temperature of 40℃ and a relative humidity of 90% was measured using the cup method specified in JIS Z 0208. 2 • 24hr). It should be noted that during the measurement, the cured adhesive layer (cured film) in the above-mentioned laminate was placed in an environment with a temperature of 40°C and a relative humidity of 90%. In addition, the laminate was mounted on the cup with the cured film facing outwards.

[0322] The results are shown in the "Water Permeability of Laminates" column of Table 2. The values ​​in parentheses represent the thickness of the cured film in the laminate (unit: μm).

[0323] In addition, using the moisture permeability (Jt) of the obtained laminate, the moisture permeability (J) of the cured film itself at a temperature of 40°C and a relative humidity of 90% is calculated based on the following formula.

[0324] 1 / Jt=(1 / J)+(1 / Jsub)

[0325] A 60 μm thick PMMA film used as the substrate membrane, measured using the cup method specified in JIS Z 0208 at 40°C and 90% relative humidity, had a water permeability (Jsub) of 70 g / (m²). 2 •24hr).

[0326] The results are shown in the "Water Permeability of Cured Film" column of Table 2. The values ​​in parentheses represent the thickness of the cured film (unit: μm).

[0327] (2) Evaluation of the adhesion between the polarizer and the PMMA film in the polarizing plate (initial)

[0328] An adhesive layer is formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with adhesive layer is cut into a length (parallel to the absorption axis of the polarizer) of 200 mm × width of 25 mm, and the adhesive layer is bonded to a glass plate to obtain a laminate. The obtained laminate is used as a test piece for determining the peel strength between the polarizer and the PMMA film. A cutting tool is placed between the polarizer and the PMMA film of the test piece, and a 30 mm peel is made from the end along the length direction. The peeled portion is clamped by the clamping part of the testing machine, and the glass plate is clamped by the lower clamping part. For the test piece in this state, a peel test is performed in an atmosphere with a temperature of 23°C and a relative humidity of 55%, according to JIS K 6854-2:1999 "Adhesives - Peel strength test method - Part 2: 180-degree peel", at a clamping movement speed of 300 mm / min. The average peel force over a length of 170 mm excluding the 30 mm clamping portion is determined and taken as the peel strength between the polarizer and the PMMA film. The results are shown in Table 2. Peel strength was measured after the polarizing plate was fabricated and placed in an environment of 23°C and 50% RH for 24 hours.

[0329] In Table 2, "fracture" refers to a condition where the peel strength is very high, and the PMMA film or polarizer fractures before the film is peeled off.

[0330] (3) Evaluation of the adhesion between the polarizer and the PMMA film in the polarizing plate (after exposure to high temperature and high humidity environment)

[0331] An adhesive layer is formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with adhesive layer is cut into a size of 200 mm in length (parallel to the absorption axis of the polarizer) × 25 mm in width, and the adhesive layer is bonded to the glass to obtain a laminate. The obtained laminate is placed in a high temperature and high humidity environment of 80°C and 90% RH for 24 hours, and then placed in an environment of 23°C and 50% RH for 24 hours. Then, a cutting tool of a cutting machine is placed between the polarizer and the PMMA film of the obtained laminate, and 30 mm is peeled off from the end along the length direction. The peeled part is clamped by the clamping part of the testing machine, and the glass plate is clamped by the lower clamping part. For the test piece in this condition, a peel test was conducted in an atmosphere of 23°C and 55% relative humidity, according to JIS K 6854-2:1999 "Adhesives - Test method for peel strength - Part 2: 180-degree peel", with a clamping and moving speed of 300 mm / min. The average peel force over a length of 170 mm excluding the 30 mm clamping portion was determined and taken as the peel strength between the polarizer and the PMMA film. The results are shown in Table 2.

[0332] [Table 2]

[0333]

[0334] Explanation of reference numerals in the attached figures

[0335] 10: First thermoplastic resin film, 15: First adhesive layer, 20: Second thermoplastic resin film, 25: Second adhesive layer, 30: Polarizing film.

Claims

1. A curable adhesive composition comprising maleic anhydride-modified compound A, unmodified polybutene B, (meth)acrylate compound C, and photopolymerization initiator D, wherein, The maleic anhydride-modified compound A is maleic anhydride-modified polymer A-1. The maleic anhydride-modified polymer A-1 is a polymer modified by introducing maleic anhydride structures as side chains of the polymer. In a total mass percentage (100% by weight) of the maleic anhydride-modified compound A and the unmodified polybutene B, the content of the maleic anhydride-modified compound A is 40% by weight or more and 90% by weight or less. When the total amount of the adhesive composition is set to 100% by mass, the combined amount of the maleic anhydride modified compound A and the unmodified polybutene B is 10% by mass or more and 50% by mass or less. The (meth)acrylate compound C comprises a monofunctional (meth)acrylate compound C-1. Of the 100% by mass of the (meth)acrylate compound C, the content of the monofunctional (meth)acrylate compound C-1 is 60% by mass or more. The monofunctional (meth)acrylate compound C-1 comprises C4-C atoms selected from (meth)acrylate cyclic alkyl ester compounds and straight-chain or branched (meth)acrylate. 36 At least one of the alkyl ester compounds, When the total amount of the adhesive composition is set to 100% by mass, the content of the (meth)acrylate compound C is 20% by mass or more and 60% by mass or less.

2. The curable adhesive composition according to claim 1, wherein, In 100% by mass of the (meth)acrylate compound C, the content of the monofunctional (meth)acrylate compound C-1 is 60% by mass or more and 99% by mass or less.

3. The curable adhesive composition according to claim 1 or 2, wherein, The monofunctional (meth)acrylate compound C-1 comprises a (meth)acrylate cyclic alkyl ester compound and a straight-chain or branched (meth)acrylate C4-C5 group. 36 Alkyl ester compounds.

4. The curable adhesive composition according to claim 1 or 2, wherein, The (meth)acrylate cycloalkyl ester compound and the (meth)acrylate straight-chain or branched C4-C... 36 In a total of 100% by mass of alkyl ester compounds, the content of the (meth)acrylate cyclic alkyl ester compound is 30% by mass or more and 80% by mass or less.

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

6. The curable adhesive composition according to claim 1 or 2, wherein, A 10 μm thick cured film comprising the curable adhesive composition exhibits a strength of 400 g / (m²) at 40°C and 90% relative humidity. 2 • 24hr) or less of permeability.

7. A polarizing plate, comprising, in sequence, a polarizing film, an adhesive layer, and a thermoplastic resin film. The adhesive layer is the cured layer of the curable adhesive composition according to any one of claims 1 to 6.

8. The polarizing plate according to claim 7, wherein, The thermoplastic resin film is a (meth)acrylic resin film.

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