KR20230127257A - Curable adhesive composition and polarizer - Google Patents

Abstract

[Problem] To provide a polarizing plate comprising a curable adhesive composition suitable for bonding a polarizer and a thermoplastic resin film, a polarizer, an adhesive layer and a thermoplastic resin film in this order, with good adhesion between the polarizer and the thermoplastic resin film.
[Solution] A curable adhesive composition containing a maleic anhydride-modified compound (A), unmodified polybutene (B), a (meth)acrylate compound (C) and a photopolymerization initiator (D), a polarizer, an adhesive layer and a thermoplastic As a polarizing plate comprising a resin film in this order, a polarizing plate in which the adhesive layer is a cured product layer of the curable adhesive composition is provided.

Description

Curable adhesive composition and polarizer

The present invention relates to a curable adhesive composition and a polarizing plate.

BACKGROUND OF THE INVENTION [0002] A polarizing plate widely used in image display devices typified by liquid crystal display devices and organic EL display devices usually has a configuration in which a thermoplastic resin film such as a protective film is bonded to one side or both sides of a polarizer. An adhesive is normally used for bonding between a polarizer and a thermoplastic resin film. Active energy ray-curable adhesives and water-based adhesives are known as the adhesive [for example, Japanese Unexamined Patent Publication No. 2009-008860 (Patent Document 1)].

Patent Document 1: Japanese Unexamined Patent Publication No. 2009-008860

An object of the present invention is to provide a curable adhesive composition suitable for bonding between a polarizer and a thermoplastic resin film. Another object of the present invention is to provide a polarizing plate comprising a polarizer, an adhesive layer and a thermoplastic resin film in this order, with good adhesion between the polarizer and the thermoplastic resin film.

The present invention provides a curable adhesive composition and a polarizing plate shown below.

[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).

[2] The content of the maleic anhydride-modified compound (A) is 40 mass% or more and 90 mass% or less of 100 mass% of the total amount of the maleic anhydride-modified compound (A) and unmodified polybutene (B) [1 ] The curable adhesive composition described in.

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

[4] The content of the monofunctional (meth)acrylate compound (C-1) is curable according to [3], wherein the content of the (meth)acrylate compound (C) is 60% by mass or more and 99% by mass or less based on 100% by mass of the (meth)acrylate compound (C). adhesive composition.

[5] The monofunctional (meth)acrylate compound (C-1) contains at least one compound selected from the group consisting of alicyclic alkyl (meth)acrylate compounds and aromatic (meth)acrylate compounds. The curable adhesive composition according to [3] or [4].

[6] The monofunctional (meth)acrylate compound (C-1) includes an alicyclic alkyl (meth)acrylate compound and a linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound [ The curable adhesive composition according to any one of 3] to [5].

[7] The content of the alicyclic alkyl (meth)acrylate compound is the total amount of the alicyclic alkyl (meth)acrylate compound and the linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound, 100 mass Curable adhesive composition as described in [6] which is 30 mass % or more and 80 mass % or less among %.

[8] The curable adhesive composition according to any one of [1] to [7] further containing a petroleum resin (E).

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

[10] The cured film having a thickness of 10 μm made of the curable adhesive composition is any one of [1] to [9] having a moisture permeability of 400 g/(m 2 24 hr) or less at a temperature of 40° C. and a relative humidity of 90% The curable adhesive composition described in.

[11] A polarizing plate comprising a polarizer, an adhesive layer and a thermoplastic resin film in this order,

The said adhesive bond layer is a polarizing plate which is a hardened|cured material layer of the curable adhesive composition as described in any one of [1]-[10].

[12] The polarizing plate according to [11], wherein the thermoplastic resin film is a (meth)acrylic resin film.

As a polarizing plate comprising a curable adhesive composition suitable for bonding a polarizer and a thermoplastic resin film, a polarizer, an adhesive layer and a thermoplastic resin film in this order, a polarizing plate having good adhesion between the polarizer and the thermoplastic resin film can be provided.

1 is a schematic cross-sectional view showing an example of the layer configuration of a polarizing plate according to the present invention.
2 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate according to the present invention.

<Curable adhesive composition>

The curable adhesive composition (hereinafter also referred to as “adhesive composition”) according to the present invention is suitable for bonding a thermoplastic resin film, and can be used, for example, for bonding a thermoplastic resin film and another thermoplastic resin film (or layer). An example of the application of the adhesive composition according to the present invention is for a polarizing plate, that is, it can be used to manufacture a polarizing plate. More specifically, the adhesive composition concerning this invention is useful as an adhesive composition used for bonding of a polarizer and a thermoplastic resin film.

In this specification, a polarizing plate refers to a laminated optical film comprising a polarizer and a thermoplastic resin film laminated on one or both surfaces thereof. In the polarizing plate, the polarizer and the thermoplastic resin film are laminated via an adhesive layer. The adhesive layer is a layer formed of an adhesive composition, more specifically, a cured product layer of the adhesive composition.

A polarizing plate may contain films or layers other than a polarizer and the said thermoplastic resin film.

The adhesive composition is a curable adhesive composition containing a maleic anhydride modified compound (A), unmodified polybutene (B), a (meth)acrylate compound (C), and a photopolymerization initiator (D). The adhesive composition may contain components other than these.

In addition, the compounds exemplified as each component that is or may be included in the adhesive composition in the present specification may be used alone or in combination of a plurality of types unless otherwise specified.

[1] maleic anhydride modified compound (A)

The maleic anhydride-modified compound (A) is a compound containing a maleic anhydride structure in a molecule. The adhesive composition may contain one type of maleic anhydride-modified compound (A), or may contain two or more types of maleic anhydride-modified compounds (A).

As a maleic anhydride-modified compound (A), the maleic anhydride-modified polymer (A-1) is mentioned.

The maleic anhydride-modified polymer (A-1) is a polymer modified by introducing a maleic anhydride structure as a side chain of a polymer. The adhesive composition may contain one type of maleic anhydride-modified polymer (A-1), or may contain two or more types of maleic anhydride-modified polymer (A-1).

The said maleic anhydride structure means the following structure.

(* indicates a binding hand to the main chain.)

In the maleic anhydride-modified polymer (A-1), examples of the maleic anhydride-modified polymer include diene polymers, polyolefin polymers, (meth)acrylic polymers, polyester polymers, polystyrene polymers, polyether polymers, and the like. can be heard These polymers may be homopolymers composed of one type of monomer or copolymers composed of two or more types of monomers.

In this specification, "(meth)acryl" shows at least 1 sort(s) chosen from the group which consists of an acryl and methacryl. The same applies to descriptions such as "(meth)acryloyl" and "(meth)acrylate".

It is preferable that maleic anhydride-modified polymer (A-1) is maleic anhydride-modified polybutadiene. Each of these polymers may be a homopolymer or a copolymer. The copolymerization monomer in the case of a copolymer is, for example, an olefin monomer.

Polybutadiene may be 1,4-polybutadiene or 1,2-polybutadiene, and includes both structural units formed by 1,4-addition and structural units formed by 1,2-addition. may be 1,4-addition may be trans addition or cis addition.

It is preferable that the maleic anhydride-modified polymer (A-1) is liquid-type from the viewpoint of being able to prepare an adhesive composition having a non-solvent type and having a good adhesive ability. A liquid type means what shows fluidity at a temperature of 25 degreeC.

The viscosity at 25°C of the liquid maleic anhydride-modified polymer (A-1) is usually 1 Pa·sec or more and 1300 Pa·sec or less, preferably 10 Pa·sec, from the viewpoint of obtaining an adhesive composition with good coatability. ·sec or more and 1000 Pa·sec or less, more preferably 15 Pa·sec or more and 700 Pa·sec or less, and still more preferably 15 Pa·sec or more and 150 Pa·sec or less.

The number average molecular weight of the maleic anhydride-modified polymer (A-1) is usually 500 or more and 15000 or less, and from the viewpoint of viscosity and coatability, it is preferably 600 or more and 12000 or less, more preferably 700 or more and 10000 or less. Preferably they are 2000 or more and 10000 or less.

The number average molecular weight of the maleic anhydride-modified polymer (A-1) can be measured as a standard polystyrene equivalent value by gel permeation chromatography (GPC).

The acid value of the maleic anhydride-modified polymer (A-1) is usually 10 KOHmg/g or more and 200 KOHmg/g or less, and from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), etc., it is preferably 15 KOHmg/g or more and 150 KOHmg/g or less, more preferably 20 KOHmg/g or more and 100 KOHmg/g or less, still more preferably 45 KOHmg/g or more and 80 KOHmg/g or less. Use of the maleic anhydride-modified polymer (A-1) having an acid value within the above range is advantageous in enhancing the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and is particularly advantageous as a polarizer based on polyvinyl alcohol. In the case of using a polarizer, it is advantageous in providing an adhesive composition having high adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film.

The acid value of the maleic anhydride-modified polymer (A-1) is measured by a neutralization titration method using phenolphthalein as an indicator according to JIS K 0070:1992.

When the total amount of the adhesive composition is 100% by mass, the content of the maleic anhydride-modified compound (A) is usually 3% by mass or more and 40% by mass or less, and the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer) From the viewpoint of, in particular, in the case of using a polyvinyl alcohol-based polarizer as a polarizer, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film, it is preferably 5% by mass or more and 35% by mass or less, more preferably It is 10 mass % or more and 30 mass % or less.

[2] Unmodified polybutene (B)

The unmodified polybutene (B) is unmodified polybutene, and is a polymer obtained by addition polymerization of butene. That it is not modified means that the side chain does not contain a reactive group or a polar group. The structural unit derived from butene contained in the unmodified polybutene (B) is preferably a structural unit derived mainly from isobutene, and a structural unit derived from normal butene may be further contained. The adhesive composition may contain one type of unmodified polybutene, or may contain two or more types of unmodified polybutene.

It is preferable that the unmodified polybutene (B) is in liquid form from the viewpoint of being able to prepare an adhesive composition having good adhesive ability in a non-solvent form. A liquid type means what shows fluidity at a temperature of 25 degreeC.

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, from the viewpoint of obtaining an adhesive composition with good coatability. ·sec or more and 3 Pa·sec or less, more preferably 0.03 Pa·sec or more and 2 Pa·sec or less.

The number average molecular weight of the unmodified polybutene (B) is usually 200 or more and 1500 or less, and from the viewpoint of viscosity and coatability, it is preferably 250 or more and 1000 or less, more preferably 300 or more and 600 or less. The number average molecular weight of the unmodified polybutene (B) can be measured by a vapor pressure molecular weight measurement method.

When the total amount of the adhesive composition is 100% by mass, the content of the unmodified polybutene (B) is usually 1% by mass or more and 20% by mass or less, and the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer) From the viewpoint, particularly in the case of using a polyvinyl alcohol-based polarizer as the polarizer, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film, it is preferably 2% by mass or more and 18% by mass or less, more preferably is 3% by mass or more and 15% by mass or less.

When the total amount of the adhesive composition is 100% by mass, the total amount of the maleic anhydride-modified compound (A) and the unmodified polybutene (B) is usually 4% by mass or more and 60% by mass or less, and the thermoplastic resin film (or layer ) From the viewpoint of the adhesive composition of the adhesive composition, in particular, in the case of using a polyvinyl alcohol-based polarizer as a polarizer, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film, preferably 5% by mass or more It is 50 mass % or less, More preferably, it is 10 mass % or more and 40 mass % or less, More preferably, it is 15 mass % or more and 30 mass % or less.

When the total amount of the maleic anhydride-modified compound (A) and the unmodified polybutene (B) in the adhesive composition is 100% by mass, the content of the unmodified polybutene (B) is usually 5% by mass or more and 65% by mass. Hereinafter, in the case of using a polyvinyl alcohol-based polarizer as a polarizer, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), in particular, from the viewpoint of increasing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film , preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less.

When the total amount of the maleic anhydride-modified compound (A) and unmodified polybutene (B) in the adhesive composition is 100% by mass, the content of the maleic anhydride-modified compound (A) is the thermoplastic resin film (or layer) From the viewpoint of the adhesion ability of the adhesive composition to, in particular, in the case of using a polyvinyl alcohol-based polarizer as a polarizer, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film, preferably 40% by mass or more 90 It is mass % or less, More preferably, it is 50 mass % or more and 80 mass % or less.

[3] (meth)acrylate compound (C)

The (meth)acrylate compound (C) is a radically polymerizable compound having one or more (meth)acryloyloxy groups in the molecule.

The adhesive composition may contain one or two or more (meth)acrylate compounds (C).

As the (meth)acrylate compound (C), a monofunctional (meth)acrylate compound (C-1) having one (meth)acryloyloxy group in the molecule and two (meth)acryloyloxy groups in the molecule bifunctional (meth)acrylate compound (C-2) having three or more (meth)acryloyloxy groups in the molecule; and polyfunctional (meth)acrylate compound (C-3) having three or more (meth)acryloyloxy groups.

The (meth)acrylate compound (C) is a monofunctional (meth)acrylate compound (C-1), a bifunctional (meth)acrylate compound (C-2) and a polyfunctional (meth)acrylate compound (C-1). 3) can each contain 1 type, or 2 or more types.

An example of the monofunctional (meth)acrylate compound (C-1) is an alkyl (meth)acrylate. As the alkyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i -Butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl Syl(meth)acrylate, dodecyl(meth)acrylate, lauryl(meth)acrylate, cetyl(meth)acrylate, stearyl(meth)acrylate, isostearyl(meth)acrylate, isomyristyl Linear or branched alkyl (meth)acrylate compounds, such as (meth)acrylate, behenyl (meth)acrylate, and tetradecyl (meth)acrylate, are mentioned.

Other examples of the monofunctional (meth)acrylate compound (C-1) include, for example,

Aralkyl (meth)acrylates such as benzyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate ) Acrylates, phenoxy (meth) acrylates such as ethoxylated -o-phenylphenol (meth) acrylate, etc., the group bonded to -O- of the ester bond (-C (= O) -O-) is directional Aromatic (meth)acrylate compounds containing a ring;

Cyclohexyl(meth)acrylate, cyclohexylmethyl(meth)acrylate, dicyclopentanyl(meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, isobornyl(meth)acrylate, etc. of, an alicyclic alkyl (meth)acrylate compound in which the group bonded to -O- of the ester bond (-C(=O)-O-) contains an alicyclic ring;

aminoalkyl (meth)acrylate compounds such as N,N-dimethylaminoethyl (meth)acrylate;

-O- of ester bonds (-C(=O)-O-), such as dicyclopentenyloxyethyl (meth)acrylate, ethylcarbitol (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate As a (meth)acrylate compound in which the group couple|bonded with contains an ether bond, those other than the above are mentioned.

As another example of the monofunctional (meth)acrylate compound (C-1), for example,

2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate A group bonded to -O- of an ester bond (-C(=O)-O-) containing a hydroxyl group, such as rate, trimethylolpropane mono(meth)acrylate, pentaerythritol mono(meth)acrylate, etc. meth)acrylate compounds;

2-carboxyethyl (meth)acrylate, ω-carboxy-polycaprolactone (n≒2) mono(meth)acrylate, 1-[2-(meth)acryloyloxyethyl]phthalic acid, 1-[2- (meth)acryloyloxyethyl]hexahydrophthalic acid, 1-[2-(meth)acryloyloxyethyl]succinic acid, 4-[2-(meth)acryloyloxyethyl]trimellitic acid, N-( meth)acryloyloxy-N',N'-dicarboxymethyl-p-phenylenediamine, etc., wherein the group bonded to -O- of the ester linkage (-C(=O)-O-) contains a carboxyl group (meth)acrylate compounds, etc. are mentioned.

Examples of the bifunctional (meth)acrylate compound (C-2) include alkylene glycol di(meth)acrylate, polyoxyalkylene glycol di(meth)acrylate, and halogen-substituted alkylene glycol di(meth)acrylate. , di(meth)acrylates of aliphatic polyols, di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecanedialkanols, di(meth)acrylates of dioxane glycols or dioxane dialkanols, bisphenol A or bisphenols di(meth)acrylate of an alkylene oxide adduct of F, epoxydi(meth)acrylate of bisphenol A or bisphenol F, and the like.

More specific examples of the bifunctional (meth)acrylate compound (C-2) include ethylene glycol di(meth)acrylate, 1,3-butanedioldi(meth)acrylate, and 1,4-butanedioldi(meth)acrylate. Acrylate, 1,6-hexanedioldi(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, neopentylglycoldi(meth)acrylate, trimethylolpropanedi(meth)acrylate, pentachloride Erythritol di(meth)acrylate, ditrimethylolpropane di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, Tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, silicon di(meth)acrylate, hydroxyl Di(meth)acrylate of cipivalic acid neopentyl glycol ester, 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane, 2,2-bis[4-(meth)acrylo Iloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, 1,3-dioxane-2,5-diyldi(meth)acrylate ) Acrylate [alias: dioxane glycoldi(meth)acrylate], acetal compound of hydroxypivalaldehyde and trimethylolpropane [chemical name: 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl -5-hydroxymethyl-1,3-dioxane] di(meth)acrylate, tris(hydroxyethyl)isocyanurate di(meth)acrylate, di(meth)acrylate of ethoxylated bisphenol A , di(meth)acrylate of propoxylated bisphenol A, di(meth)acrylate of ethoxylated bisphenol F, di(meth)acrylate of propoxylated bisphenol F, and the like.

The bifunctional (meth)acrylate (C-2) preferably has at least one alicyclic backbone or at least one aromatic ring in the molecule, and more preferably has at least one aromatic ring.

The bifunctional (meth)acrylate (C-2) is, from the viewpoint of the moisture permeability of the cured product, compatibility with the maleic anhydride-modified compound (A), and adhesion to the thermoplastic resin film (particularly the (meth)acrylic resin film), as follows. It is preferable to contain the compound represented by a formula, and it is more preferable that it is a compound represented by the following formula.

(Wherein, R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group, X represents ethylene oxide (-C ₂ H ₄ O-) or propylene oxide (-C ₃ H ₆ O-), n represents an integer from 1 to 20, and m represents an integer from 1 to 20.)

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 still more preferably 4 to 13.

As the polyfunctional (meth)acrylate compound (C-3) having three or more (meth)acryloyloxy groups in the molecule, glycerin tri(meth)acrylate, alkoxylated glycerin tri(meth)acrylate, trimethylolpropane Tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, di poly(meth)acrylates of trifunctional or higher functional aliphatic polyols such as pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate;

poly(meth)acrylates of trifunctional or higher halogen-substituted polyols;

tri(meth)acrylate of an alkylene oxide adduct of glycerin;

tri(meth)acrylate of an alkylene oxide adduct of trimethylolpropane;

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

Tris(hydroxyethyl) isocyanurate tri(meth)acrylate etc. are mentioned.

The (meth)acrylate compound (C) is a monofunctional (meth)acrylate compound (C- 1) is preferably included.

When the total amount of the (meth)acrylate compound (C) is 100% by mass, the content of the monofunctional (meth)acrylate compound (C-1) is usually 60% by mass or more, and the thermoplastic resin film (or layer ) From the viewpoint of the adhesive composition's adhesive ability to, it is preferably 70% by mass or more, more preferably 80% by mass or more.

When the total amount of the (meth)acrylate compound (C) is 100% by mass, the content of the monofunctional (meth)acrylate compound (C-1) may be 100% by mass, but the mechanical strength of the cured product of the adhesive composition Furthermore, from the viewpoint of the mechanical strength of the polarizing plate produced using the adhesive composition, it is preferably 99% by mass or less, more preferably 98% by mass or less, and may be 90% by mass or less.

When the content of the monofunctional (meth)acrylate compound (C-1) is less than 100% by mass, the remainder of the (meth)acrylate compound (C) is a difunctional (meth)acrylate compound (C-2) and/or or a polyfunctional (meth)acrylate compound (C-3), preferably a bifunctional (meth)acrylate compound (C-2).

From the viewpoint of reducing the viscosity of the adhesive composition and the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), the monofunctional (meth)acrylate compound (C-1) is an alicyclic alkyl (meth)acrylic acid. It is preferable to contain at least 1 sort(s) of compound selected from the group which consists of a late compound and an aromatic (meth)acrylate compound.

In addition, from the viewpoint of the wet heat durability of the polarizing plate using the polyvinyl alcohol-based polarizer, that is, from the viewpoint of providing a polarizing plate having good adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film even after being placed in a moist heat environment, monofunctional (meth) The acrylate compound (C-1) preferably contains at least one selected from alicyclic alkyl (meth)acrylate compounds and linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compounds. It is more preferable to include a formula alkyl (meth)acrylate compound and a linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound.

Examples of the linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound include butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and nonyl (meth)acrylate. Late, 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, behenyl (meth)acrylate, tetradecyl (meth)acrylate, etc. are mentioned.

From the viewpoint of wet heat durability of a polarizing plate using a polyvinyl alcohol-based polarizer, the number of carbon atoms of the linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound is preferably 8 or more, more preferably 10 or more. , particularly preferably 12 or more. 24 or less may be sufficient as the said carbon number, and 22 or less may be sufficient as it.

When the monofunctional (meth)acrylate compound (C-1) contains both an alicyclic alkyl (meth)acrylate compound and a linear or branched C ₄ -C ₃₆ alkyl (meth)acrylate compound, the adhesive composition From the viewpoint of adhesive ability and the wet heat durability of a polarizing plate using a polyvinyl alcohol-based polarizer, the content of the alicyclic alkyl (meth) acrylate compound is an alicyclic alkyl (meth) acrylate compound and straight or branched C Of 100 mass% of the total amount of ₄ -C ₃₆ alkyl (meth)acrylate compounds, it is preferably 30 mass% or more and 90 mass% or less, more preferably 30 mass% or more and 80 mass% or less, still more preferably 40 It is 75 mass % or more by mass %, and more preferably 50 mass % or more and 70 mass % or less.

When the total amount of the adhesive composition is 100% by mass, the content of the (meth)acrylate compound (C) is usually 15% by mass or more and 75% by mass or less, and the adhesive composition adheres to the thermoplastic resin film (or layer). From the viewpoint of ability, it is preferably 15% by mass or more and 70% by mass or less, more preferably 20% by mass or more and 60% by mass or less.

[4] photopolymerization initiator (D)

The photopolymerization initiator (D) is not particularly limited as long as it is a compound capable of initiating polymerization of the (meth)acrylate compound (C) by generating active radicals, acids, and the like under the action of light.

The adhesive composition may contain only 1 type of photoinitiator (D), and may contain 2 or more types.

Although it does not restrict|limit especially as a photoinitiator (D), Oxime type compounds, such as an O-acyl oxime compound, an alkylphenone compound, an acylphosphine oxide compound, etc. are mentioned.

The O-acyloxime compound is a compound having a structure represented by the following formula (d). Hereinafter, * represents a binding hand.

As an O-acyloxime compound, N-benzoyloxy-1-(4-phenylsulfanylphenyl)butan-1-one-2-imine, N-benzoyloxy-1-(4-phenylsulfanylphenyl)octan-1 -One-2-imine, N-benzoyloxy-1-(4-phenylsulfanylphenyl)-3-cyclopentylpropan-1-one-2-imine, N-acetoxy-1-[9-ethyl-6 -(2-methylbenzoyl)-9H-carbazol-3-yl]ethane-1-imine, N-acetoxy-1-[9-ethyl-6-{2-methyl-4-(3,3-dimethyl -2,4-dioxacyclopentanylmethyloxy)benzoyl}-9H-carbazol-3-yl]ethane-1-imine, N-acetoxy-1-[9-ethyl-6-(2-methylbenzoyl) -9H-carbazol-3-yl]-3-cyclopentylpropan-1-imine, N-benzoyloxy-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl ]-3-cyclopentylpropan-1-one-2-imine, N-acetyloxy-1-[4-(2-hydroxyethyloxy)phenylsulfanylphenyl]propan-1-one-2-imine, N -Acetyloxy-1-[4-(1-methyl-2-methoxyethoxy)-2-methylphenyl]-1-(9-ethyl-6-nitro-9H-carbazol-3-yl)methan-1 - Immigration, etc.

Commercially available products such as Igacure (trade name) OXE01, OXE02, and OXE03 (above, manufactured by BASF), N-1919, NCI-930, and NCI-831 (above, manufactured by ADEKA) may also be used.

The alkylphenone compound is a compound having a partial structure represented by the following formula (d4) or a partial structure represented by the following formula (d5). Among these partial structures, the benzene ring may have a substituent.

As a compound having a structure represented by formula (d4), 2-methyl-2-morpholino-1-(4-methylsulfanylphenyl)propan-1-one, 2-dimethylamino-1-(4-morpholino Nophenyl)-2-benzylbutan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]butan-1-one etc. can be mentioned.

Commercially available products such as Omnirad (trade name) 369, 907, and 379 (above, manufactured by IGM Resins B.V.) may be used.

As a compound having a structure represented by formula (d5), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxy Toxy) phenyl] propan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1- (4-isopropenylphenyl) propan-1-one oligomer, α, α- Diethoxy acetophenone, benzyl dimethyl ketal, etc. are mentioned.

A commercially available product such as Omnirad (trade name) 184 (manufactured by IGM Resins B.V.) may be used.

As the acylphosphine oxide compound, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (for example, trade name "Omnirad 819" (manufactured by IGM Resins B.V.)), 2,4,6-trimethylbenzoyldiphenylphos A pin oxide etc. are mentioned.

As further examples of the photopolymerization initiator (D),

benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

Benzophenone, o-benzoyl methyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3',4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, benzophenone compounds such as 2,4,6-trimethylbenzophenone and 4,4'-di(N,N'-dimethylamino)-benzophenone;

xanthone compounds such as 2-isopropylthioxanthone and 2,4-diethylthioxanthone;

anthracene compounds such as 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 2-ethyl-9,10-diethoxyanthracene;

quinone compounds such as 9,10-phenanthrenequinone, 2-ethylanthraquinone, and camphorquinone;

Benzyl, methyl phenylglyoxylate, titanocene compounds, etc. are mentioned.

When the total amount of the adhesive composition is 100% by mass, the content of the photopolymerization initiator (D) is usually 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 for the thermoplastic resin film (or layer). From the viewpoint of the adhesive ability of the composition, 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 (for example, 8% by mass or less).

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

[5] Tackifier

The adhesive composition may further contain a tackifier. The tackifying resin is not particularly limited and can be appropriately selected from known ones, 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, phenol-based resins, xylene-based resins, and the like.

Especially, it is preferable that the adhesive composition further contains a petroleum resin (E). Adhesiveness can be improved and the water vapor transmission rate of the cured film formed from adhesive composition can be reduced because adhesive composition further contains a petroleum resin (E).

An adhesive composition capable of forming a cured film with low moisture permeability is suitable for applications requiring suppression of entry and exit of moisture through the cured film. For example, in a polarizing plate in which a thermoplastic resin film is laminated on at least one surface of a polarizer via an adhesive layer, or an image display panel including the same, if the adhesive layer has low moisture permeability, the polarizing plate or image display panel resulting from the entry and exit of moisture It becomes possible to suppress the curl (bending) of.

The fact that the adhesive composition further contains a petroleum resin (E) may be advantageous also in improving the adhesion between the polarizer and the thermoplastic resin film.

Examples of the petroleum resin (E) include aromatic petroleum resins, aliphatic petroleum resins, cyclic aliphatic petroleum resins, aliphatic/aromatic petroleum resins, and coumarone resins. Moreover, what hydrogenated these resins etc. are mentioned.

The aromatic petroleum resin is a resin containing one or two or more types of structural units derived from aromatic hydrocarbons, and hydrogenated resins or modified resins may be used.

The aromatic petroleum resin is preferably a C9 petroleum resin. The C9-based petroleum resin is a resin obtained by copolymerizing a C9 fraction, and may be obtained by hydrogenating the resin or modifying the resin.

The C9-based petroleum resin may be a resin obtained by copolymerizing a C9 fraction with other monomer components, hydrogenated resin, or modified resin. As another monomer component, C5 fraction is mentioned.

Examples of the C9 fraction include petroleum fractions having about 8 to 10 carbon atoms such as styrene, alkylstyrene, vinyltoluene, 1-methyl-1-phenylethylene, indene, and methylindene.

Examples of the C5 fraction include petroleum fractions having about 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, isoprene, and piperylene.

Further, the petroleum resin (E) may be a C5-based petroleum resin obtained by copolymerizing the above-mentioned C5 oil component, a hydrogenated C5-based petroleum resin, or a modified resin. Alternatively, an alicyclic hydrocarbon-based resin polymerized after cyclodimerization of the C5 fraction may be used. As an alicyclic hydrocarbon-type resin, the polymer etc. which contain the structural unit derived from dicyclopentadiene are mentioned.

The weight average molecular weight of the petroleum resin (E) is usually 500 or more and 10000 or less, from the viewpoint of reducing the water vapor permeability of the cured film formed from the adhesive composition and the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer). , It is preferably 500 or more and 7000 or less, more preferably 600 or more and 5000 or less, and still more preferably 600 or more and 3000 or less.

The weight average molecular weight of a petroleum resin (E) can be measured as a standard polystyrene conversion value by GPC.

In the case where the adhesive composition contains a petroleum resin (E), when the total amount of the adhesive composition is 100% by mass, the content of the petroleum resin (E) is from the viewpoint of reducing the water vapor transmission rate of a cured film formed from the adhesive composition, And, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), in particular, in the case of using a polyvinyl alcohol-based polarizer as a polarizer, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizer and the thermoplastic resin film , Preferably it is 20 mass % or more and 70 mass % or less, More preferably, it is 30 mass % or more and 65 mass % or less.

The water vapor transmission rate of the cured film formed from the adhesive composition is preferably low. The cured film having a thickness of 10 μm made of the adhesive composition has a moisture permeability measured by the cup method specified in JIS Z 0208 under conditions of a temperature of 40° C. and a relative humidity of 90%, preferably 400 g/(m 2 24 hr) or less. , more preferably 300 g/(m 2 24 hr) or less, still more preferably 200 g/(m 2 24 hr) or less. The moisture permeability is usually 1 g/(m 2 24 hr) or more, for example 5 g/(m 2 24 hr) or more.

Specifically, the moisture permeability J of the cured film made of the adhesive composition is obtained by preparing a laminate formed by forming the cured film on a base film having a known moisture permeability, measuring the moisture permeability of the laminate by the above method, and using the measurement result. It can obtain|require based on the following formula.

1/Jt=(1/J)+(1/Jsub)

In the above formula, Jt is the water vapor transmission rate of the laminate, and Jsub is the water vapor transmission rate of the base film. As a base film, the same thing as the thermoplastic resin film mentioned later can be used. When measuring the moisture permeability of a laminate according to JIS Z 0208, the laminate is adhered to a cup with the cured film facing outward.

Regarding the laminate, when a (meth)acrylic resin film having a thickness of, for example, 60 μm is used as the base film, the laminate of the (meth)acrylic resin film and a cured film having a thickness of 10 μm made of an adhesive composition is JIS Z The moisture permeability measured by the cup method specified in No. 0208 under conditions of a temperature of 40 ° C and a relative humidity of 90% is preferably 55 g / (m 2 24 hr) or less, more preferably 50 g / (m 2 24 hr) or less. The moisture permeability is usually 1 g/(m 2 24 hr) or more, for example 5 g/(m 2 24 hr) or more.

[6] Other ingredients

The adhesive composition may contain other components other than the above.

Examples of other components include curable components other than (meth)acrylate compound (C) and crosslinking agents; Additives, such as a coupling agent, antioxidant, a ultraviolet absorber, and a heat stabilizer, are mentioned.

[7] Viscosity of adhesive composition

The viscosity of the adhesive composition at 25°C is preferably 10000 mPa·sec or less, more preferably 2 mPa·sec or more and 7000 mPa·sec or less, and 300 mPa·sec or more and 5000 mPa·sec or less. it is more preferable

The viscosity of the adhesive composition at 25°C can be measured with an E-type viscometer.

<Polarizer>

The adhesive composition according to the present invention is suitable for bonding a thermoplastic resin film, and can be used for bonding a thermoplastic resin film and another thermoplastic resin film (or layer), for example. An example of the application of the adhesive composition according to the present invention is for polarizing plates, that is, it can be used to manufacture polarizing plates. More specifically, the adhesive composition according to the present invention is useful as an adhesive composition used for bonding a polarizer and a thermoplastic resin film such as a protective film laminated thereon.

A polarizing plate according to the present invention includes a polarizer and a thermoplastic resin film laminated on at least one surface thereof via an adhesive layer formed from the adhesive composition. The adhesive layer is a layer of a cured product of the adhesive composition.

In the polarizing plate according to the present invention, since the polarizer and the thermoplastic resin film are adhered using the adhesive composition, the adhesion between the polarizer and the thermoplastic resin film can be improved, and the moist heat durability of the polarizing plate can be improved. . That is, according to the present invention, it is possible to provide a polarizing plate having good adhesion between the polarizer and the thermoplastic resin film even after being placed in a moist heat environment.

The polarizing plate according to the present invention can be suitably used for image display devices such as liquid crystal display devices and organic EL devices.

[1] Configuration of polarizing plate

Examples of the layer structure of the polarizing plate according to the present invention are shown in FIGS. 1 and 2 .

As shown in FIG. 1, the polarizing plate according to the present invention may include a polarizer 30, a first adhesive layer 15, and a first thermoplastic resin film 10 in this order, that is, a polarizer 30 And, it may include a first thermoplastic resin film 10 laminated and bonded through the first adhesive layer 15 on one side thereof.

It is preferable that the 1st adhesive bond layer 15 and the 1st thermoplastic resin film 10 are in direct contact.

It is preferable that the polarizer 30 and the first adhesive layer 15 are in direct contact.

Further, as shown in FIG. 2 , the polarizing plate according to the present invention includes a polarizer 30, a first thermoplastic resin film 10 laminated and bonded on one side thereof via a first adhesive layer 15, and a polarizer 30 ) may include a second thermoplastic resin film 20 laminated and bonded via the second adhesive layer 25 on the other side of the film.

It is preferable that the 1st adhesive bond layer 15 and the 1st thermoplastic resin film 10 are in direct contact.

It is preferable that the polarizer 30 and the first adhesive layer 15 are in direct contact.

It is preferable that the second adhesive layer 25 and the second thermoplastic resin film 20 are in direct contact.

It is preferable that the polarizer 30 and the second adhesive layer 25 are in direct contact.

When the polarizing plate has the first adhesive layer 15 and the second adhesive layer 25, either one may be formed of the adhesive composition according to the present invention, and both adhesive layers are formed of the adhesive composition according to the present invention it may be It is preferable that the adhesive layer formed from the adhesive composition concerning this invention is an adhesive layer on the visual recognition side (an adhesive layer far from the adhesive layer mentioned later).

In the case where both adhesive layers are formed from the adhesive composition according to the present invention, these adhesive compositions may have the same composition or different compositions.

It is not limited to the example of FIGS. 1 and 2, and the polarizing plate according to the present invention may include other layers (or films) other than the above. Other layers include, for example, a pressure-sensitive adhesive layer laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30; a separate film laminated on the outer surface of the pressure-sensitive adhesive layer (also called a "release film"); A protective film laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30 (also called a "surface protection film"); An optical functional film (or layer) laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30 through an adhesive layer or a pressure-sensitive adhesive layer, and the like.

[2] Polarizer

The polarizer 30 is a film having a function of selectively transmitting linearly polarized light in one direction from natural light. As the polarizer 30, for example, an iodine polarizer in which iodine as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, and a dye system in which a dichroic dye as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. A polarizer and a coating type polarizer obtained by coating a dichroic dye in a lyotropic liquid crystal state and aligning and fixing the polarizer. 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.

The polarizer 30 is not limited to an absorption-type polarizer, but a reflection-type polarizer that selectively transmits linearly polarized light in one direction from natural light and reflects linearly polarized light in another direction, or a scattering-type polarizer that scatters linearly polarized light in another direction. Although it may be a polarizer, an absorption type polarizer is preferable from the viewpoint of excellent visibility when the polarizing plate is applied to an image display device or the like.

Among them, the polarizer 30 is more preferably a polyvinyl alcohol-based polarizer composed of a polyvinyl alcohol-based resin, adsorbing and orienting a dichroic dye such as iodine or a dichroic dye on a polyvinyl alcohol-based resin film. A polyvinyl alcohol-based polarizer is more preferred, and a polyvinyl alcohol-based polarizer obtained by adsorbing and orienting iodine on a polyvinyl alcohol-based resin film is particularly preferred.

A polyvinyl alcohol-type polarizer can be manufactured by a conventionally well-known method using a polyvinyl alcohol-type resin film (or layer).

The thickness of the polarizer 30 can be 30 μm or less, and is preferably 25 μm or less (for example, 20 μm or less, further 15 μm or less, further 10 μm or less, further 8 μm or less). The thickness of the polarizer 30 is 2 micrometers or more normally. Reducing the thickness of the polarizer 30 is advantageous for reducing the thickness of a polarizing plate and, by extension, an image display device to which it is applied.

[3] Thermoplastic resin film

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 each contain a light-transmitting (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin-based resin (polyethylene resin, polypropylene-based resin, etc.) , polyolefin-based resins such as cyclic polyolefin-based resins (norbornene-based resins and the like); cellulose ester-based resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resin; Or it may be a film containing a mixture or copolymer thereof.

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may each be an unstretched film or a uniaxially or biaxially stretched film. Biaxial stretching may be simultaneous biaxial stretching in which the film is simultaneously stretched in two stretching directions, or sequential biaxial stretching in which the film is stretched in a first direction and then in a second direction different from the first direction.

The first thermoplastic resin film 10 and/or the second thermoplastic resin film 20 may be a protective film that plays a role of protecting the polarizer 30, or may be a protective film having an optical function such as a retardation film. there is.

For example, by stretching the film containing the thermoplastic resin (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer or the like on the thermoplastic resin film, a retardation film to which an arbitrary retardation value is applied can be obtained.

The (meth)acrylic resin may be, for example, a polymer containing methacrylic acid ester as a main monomer (containing 50% by mass or more), and is preferably a copolymer in which methacrylic acid ester and other copolymerization components are copolymerized.

In one embodiment, (meth)acrylic-type resin contains methyl methacrylate as a copolymerization component, or contains methyl methacrylate and methyl acrylate.

As other copolymerization components other than methyl acrylate, for example, ethyl methacrylate, n-, i- or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-methacrylate methacrylic acid esters other than methyl methacrylate, such as ethylhexyl and 2-hydroxyethyl methacrylate;

acrylic esters such as ethyl acrylate, n-, i- or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate;

2-(hydroxymethyl)methyl acrylate, 2-(1-hydroxyethyl)methyl acrylate, 2-(hydroxymethyl)ethyl acrylate, 2-(hydroxymethyl)n-, i- or t-butyl acrylate, etc. hydroxyalkyl acrylic acid esters of;

unsaturated acids such as methacrylic acid and acrylic acid;

halogenated styrenes such as chlorostyrene and bromostyrene;

substituted styrenes such as vinyltoluene and α-methylstyrene;

unsaturated nitriles such as acrylonitrile and methacrylonitrile;

unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride;

unsaturated imides such as phenyl maleimide and cyclohexyl maleimide;

Monofunctional monomers, such as these, are mentioned.

As for the said other monofunctional monomer, only 1 type may be used independently, and 2 or more types may be used together.

A polyfunctional monomer may be used as the other copolymerization component.

Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and nonaethylene glycol di. What esterified the hydroxyl group of both terminals of ethylene glycol, such as (meth)acrylate and tetradecaethylene glycol di(meth)acrylate, or its oligomer with (meth)acrylic acid;

What esterified the hydroxyl groups of both terminals of propylene glycol or its oligomer with (meth)acrylic acid;

What esterified the hydroxyl group of dihydric alcohol, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate, with (meth)acrylic acid;

bisphenol A, alkylene oxide adducts of bisphenol A, or those obtained by esterifying the hydroxyl groups at both terminals of halogen-substituted products thereof with (meth)acrylic acid;

What esterified polyhydric alcohols, such as trimethylol propane and pentaerythritol, with (meth)acrylic acid, and what ring-opened the epoxy group of glycidyl (meth)acrylate to these terminal hydroxyl groups;

dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen-substituted products thereof, or alkylene oxide adducts thereof with ring-opening addition of an epoxy group of glycidyl (meth)acrylate;

aryl (meth)acrylate; Aromatic divinyl compounds, such as divinylbenzene;

etc. can be mentioned.

Especially, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are used preferably.

The (meth)acrylic resin may be one modified by a reaction between the functional groups of the copolymer. Examples of the reaction include a demethanol condensation reaction in the high molecular chain between a methyl ester group of methyl (meth)acrylate and a hydroxyl group of 2-(hydroxymethyl)methyl acrylate, and a carboxyl group of (meth)acrylic acid and a hydroxyl group of 2-(hydroxymethyl) acrylate. ) The dehydration condensation reaction in the high molecular chain of the hydroxyl group of methyl acrylate, etc. are mentioned.

The glass transition temperature of the (meth)acrylic resin is preferably 80°C or higher and 160°C or lower. The glass transition temperature is determined by adjusting the polymerization ratio of the methacrylic acid ester monomer and the acrylic acid ester monomer, the carbon chain length of each ester group and the type of functional groups they have, and the polymerization ratio of the polyfunctional monomer to the entire monomer. can be controlled

As a means for increasing the glass transition temperature of (meth)acrylic resin, it is also effective to introduce a cyclic structure into the main chain of the polymer. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, and a lactone structure. Specifically, cyclic acid anhydride structures, such as a glutaric anhydride structure and a succinic anhydride structure; Cyclic imide structures, such as a glutarimide structure and a succinimide structure; and lactone ring structures such as butyrolactone and valerolactone.

As the content of the cyclic structure in the main chain is increased, the glass transition temperature of the (meth)acrylic resin tends to be increased.

A method in which a cyclic acid anhydride structure or a cyclic imide structure is introduced by copolymerizing a monomer having a cyclic structure such as maleic anhydride or maleimide; a method of introducing a cyclic acid anhydride structure by dehydration/demethanol condensation reaction after polymerization; It can be introduced by a method of reacting an amino compound to introduce a cyclic imide structure.

The resin (polymer) having a lactone ring structure is obtained by preparing a polymer having a hydroxyl group and an ester group in the polymer chain, and then heating the hydroxyl group and ester group in the obtained polymer to form an organic phosphorus compound or the like as necessary. It can be obtained by a method of forming a lactone ring structure by cyclocondensation in the presence of a catalyst.

The 1st thermoplastic resin film 10 and the 2nd thermoplastic resin film 20 may contain additives as needed. Examples of additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact resistance modifiers, and surfactants.

The (meth)acrylic resin may contain acrylic rubber particles as an impact modifier from the viewpoint of film formability to a film, impact resistance of the film, and the like. The acrylic rubber particles are particles containing an acrylic acid ester-based elastomer as an essential component, and examples thereof include those having a single-layer structure containing substantially only this elastomer, and those having a multi-layer structure containing this elastomer as one layer. .

As an example of the elastic polymer, a crosslinked elastic copolymer obtained by copolymerizing alkyl acrylate as a main component with other vinylic monomers and crosslinkable monomers copolymerizable therewith can be given.

Examples of the alkyl acrylate serving as the main component of the elastomer include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, etc., in which the number of carbon atoms in the alkyl group is 1 to 8, and the alkyl group has 4 or more carbon atoms. Alkyl is preferably used.

Examples of other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule. More specifically, methacrylic acid esters such as methyl methacrylate; Aromatic vinyl compounds, such as styrene; Vinyl cyan compounds, such as acrylonitrile, etc. are mentioned.

Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, more specifically, ethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, etc. (meth)acrylates of polyhydric alcohols; alkenyl esters of (meth)acrylic acid such as allyl (meth)acrylate; Divinylbenzene etc. are mentioned.

At least one of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is preferably a film containing a (meth)acrylic resin ((meth)acrylic resin film), and the (meth)acrylic resin film The resin film is preferably laminated and bonded to the polarizer 30 via an adhesive layer formed from the adhesive composition according to the present invention.

The adhesive composition according to the present invention can exhibit particularly good adhesion when the thermoplastic resin film is a (meth)acrylic resin film. Therefore, the adhesive composition concerning this invention can be used suitably for bonding of a polarizer and a (meth)acrylic-type resin film.

The (meth)acrylic resin film preferably contains a (meth)acrylic resin as its resin component.

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be films composed of the same thermoplastic resin or films composed of mutually different thermoplastic resins. The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be the same or different in thickness, the presence or absence of additives, their types, phase difference characteristics, and the like.

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

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

The first thermoplastic resin film 10 and/or the second thermoplastic resin film 20 has a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, You may be equipped with surface treatment layers (coating layers), such as an antifouling layer and a conductive layer.

The thickness of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is usually 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, respectively. or less, 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 may be 50 μm or less and 40 μm or less, respectively. Reducing the thickness of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is advantageous for reducing the thickness of a polarizing plate and, by extension, an image display device to which it is applied.

Surface modification treatment such as saponification treatment, plasma treatment, corona treatment, and priming is performed on the surfaces of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 to which the adhesive composition is applied, from the viewpoint of improving adhesion, also good

[4] Production of polarizing plate and adhesive layer

By laminating and bonding the first thermoplastic resin film 10 on one side of the polarizer 30 via the first adhesive layer 15, a polarizing plate having the structure shown in FIG. 1 can be obtained, and the other side of the polarizer 30 The polarizing plate of the structure shown in FIG. 2 can be obtained by further laminating and adhering the 2nd thermoplastic resin film 20 to the surface via the 2nd adhesive bond layer 25.

In the case of manufacturing a polarizing plate having both the first thermoplastic resin film 10 and the second thermoplastic resin film 20 (hereinafter collectively referred to simply as a "thermoplastic resin film"), these thermoplastic resin films are produced step by step. may be laminated and bonded on one side at a time, or both sides of the thermoplastic resin film may be laminated and bonded at the same time.

In the polarizing plate of the structure shown in FIG. 1, the 1st adhesive bond layer 15 is formed from the adhesive composition concerning this invention. The first adhesive layer 15 is a cured product layer of the adhesive composition according to the present invention.

In the polarizing plate having the configuration shown in FIG. 2 , at least one of the first adhesive layer 15 and the second adhesive layer 25 is formed of the adhesive composition according to the present invention. The first adhesive layer 15 and/or the second adhesive layer 25 are cured layers of the adhesive composition according to the present invention.

In the polarizing plate having the configuration shown in Fig. 2, the first adhesive layer 15 and the second adhesive layer 25 are formed of the adhesive composition according to the present invention, and the other is different from the adhesive composition according to the present invention. It may be formed from other, different adhesive compositions.

Examples of other adhesive compositions include conventionally known water-based adhesives and active energy ray-curable adhesives.

Examples of water-based adhesives include conventionally known adhesive compositions using a polyvinyl alcohol-based resin or a urethane resin as a main component.

An active energy ray-curable adhesive is an adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. In the case of using an active energy ray-curable adhesive, the adhesive layer of the polarizing plate is a cured product layer of the adhesive.

The active energy ray-curable adhesive may be an adhesive containing an epoxy-based compound curable by cationic polymerization as a curable component, and is preferably an ultraviolet curable adhesive containing such an epoxy-based compound as a curable component. An epoxy-based compound means a compound having an average of one or more, preferably two or more epoxy groups in a molecule. An epoxy-type compound may use only 1 type, and may use 2 or more types together.

Examples of the epoxy compound include hydrogenated epoxy compounds obtained by reacting epichlorohydrin with an alicyclic polyol obtained by subjecting an aromatic ring of an aromatic polyol to a hydrogenation reaction (glycidyl ether of a polyol having an alicyclic ring); Aliphatic epoxy-type compounds, such as polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide adduct; and an alicyclic epoxy-based compound which is an epoxy-based compound having one or more epoxy groups bonded to an alicyclic ring in a molecule.

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

When the active energy ray-curable adhesive contains an epoxy-based compound curable by cationic polymerization as a curable component, it is preferable to contain a photocationic polymerization initiator. As a photocationic polymerization initiator, it is aromatic diazonium salt, for example; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; An iron-alene complex etc. are mentioned.

When the active energy ray-curable adhesive contains a radically polymerizable component such as a (meth)acrylic compound, it is preferable to contain an optical radical polymerization initiator. Examples of the photoradical polymerization initiator include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthone, fluorenone, camphaquinone, benzaldehyde, anthraquinone, and the like.

Adhesion between the polarizer 30 and the thermoplastic resin film is performed by applying an adhesive composition to the bonding surface of the polarizer 30 and/or the bonding surface of the thermoplastic resin film, or injecting the adhesive composition between the polarizer 30 and the thermoplastic resin film. and overlapping both films through a layer of an adhesive composition, and bonding them by pressing them from the top and bottom using, for example, a bonding roll or the like.

For the formation of the adhesive composition layer, various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater can be used. Moreover, the method of casting|flow_spreading an adhesive composition in the meantime may be sufficient, supplying continuously the polarizer 30 and the thermoplastic resin film so that both bonding surfaces may become inside.

Before applying the adhesive composition, to one or both of the bonding surfaces of the polarizer 30 and the thermoplastic resin film, adhesion facilitating treatment such as saponification treatment, corona discharge treatment, plasma treatment, flame treatment, priming treatment, anchor coating treatment ( surface activation treatment) may be performed.

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

A light source used for irradiating active energy rays may be any light source capable of generating ultraviolet rays, electron beams, X-rays, or the like. In particular, low-pressure mercury-vapor lamps, medium-pressure mercury-vapor lamps, high-pressure mercury-vapor lamps, ultra-high-pressure mercury-vapor lamps, chemical lamps, black light lamps, microwave-excited mercury-vapor lamps, metal halide lamps, etc., which have a luminescence distribution at a wavelength of 400 nm or less, are suitably used.

The thickness of the adhesive layer formed from the adhesive composition according to the present invention, in the case of a 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. , more preferably 2 μm or more and 50 μm or less. From the viewpoint of reducing the thickness of the polarizing plate, the thickness of the adhesive layer is preferably 30 μm or less, and further preferably 20 μm or less.

The thickness of the first adhesive layer 15 and the second adhesive layer 25 may be the same or different.

[5] Other components of the polarizing plate

[5-1] Optical functional film

The polarizing plate may include an optical functional film other than the polarizer 30 for imparting a desired optical function, and a suitable example thereof is a retardation film.

As described above, although the first thermoplastic resin film 10 and/or the second thermoplastic resin film 20 may serve as a retardation film, a retardation film may be laminated separately from the thermoplastic resin film. In the latter case, the retardation film may be laminated on the outer surface of the first thermoplastic resin film 10 and/or the second thermoplastic resin film 20 through an adhesive layer or an adhesive layer.

Examples of the retardation film include a birefringent film composed of a stretched film of a thermoplastic resin having light transmission properties; A film in which discotic liquid crystals or nematic liquid crystals are aligned and fixed; What the said liquid crystal layer was formed on the base film, etc. are mentioned.

The base film is usually a film made of a thermoplastic resin, and an example of the thermoplastic resin is a cellulose ester-based resin such as triacetyl cellulose.

As the thermoplastic resin forming the birefringent film, those described for the first and second thermoplastic resin films 10 and 20 can be used.

Examples of other optical functional films (optical members) that can be included in the polarizing plate are light collecting plates, brightness enhancing films, reflective layers (reflective films), transflective layers (transflective reflective films), light diffusion layers (light diffusion films), and the like. These are generally provided when the polarizing plate is a polarizing plate arranged on the back side (backlight side) of the liquid crystal cell.

[5-2] Adhesive layer

The polarizing plate according to the present invention may contain a pressure-sensitive adhesive layer for bonding it to an image display element such as a liquid crystal cell or an organic EL element, or another optical member. The pressure-sensitive adhesive layer is laminated on the outer surface of the polarizer 30 in the polarizing plate having the configuration shown in FIG. 1 and on the outer surface of the first thermoplastic resin film 10 or the second thermoplastic resin film 20 in the polarizing plate having the configuration shown in FIG. 2 can do.

As the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, those having (meth)acrylic resins, silicone-based resins, polyester-based resins, polyurethane-based resins, polyether-based resins and the like as base polymers can be used. Among them, from the viewpoints of transparency, adhesive strength, reliability, weatherability, heat resistance, reworkability and the like, (meth)acrylic pressure-sensitive adhesives are preferable.

The thickness of the pressure-sensitive adhesive layer is determined depending on its adhesive strength and the like, and is suitably in the range of 1 µm or more and 50 µm or less, preferably 2 µm or more and 40 µm or less.

The polarizing plate may include a separate film laminated on the outer surface of the pressure-sensitive adhesive layer. The separation film may be a film made of polyethylene-based resins such as polyethylene, polypropylene-based resins such as polypropylene, and polyester-based resins such as polyethylene terephthalate. Especially, the stretched film of polyethylene terephthalate is preferable.

If necessary, the pressure-sensitive 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, and the like.

[5-3] protection film

The polarizing plate according to the present invention may include a protective film for protecting its surface (thermoplastic resin film surface, polarizer surface, etc.). A protection film is peeled off for every adhesive layer it has, after a polarizing plate is bonded to an image display element or another optical member, for example.

A protection film is comprised, for example of a base film and the adhesive layer laminated|stacked on it. Regarding the pressure-sensitive adhesive layer, the above description is cited.

The resin constituting the base film may be, for example, a thermoplastic resin such as 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, and a polycarbonate-based resin. there is. Preferably, they are polyester-type resins, such as polyethylene terephthalate.

Example

Hereinafter, the present invention will be described more specifically by showing examples, but the present invention is not limited by these examples. In the examples, % and parts representing content or amount used are based on mass 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.

<Example 1>

(1) Preparation of Curable Adhesive Composition

The components shown in Table 1 were mixed in the compounding amounts shown in Table 1 to prepare curable adhesive composition A. The unit of the compounding quantity of each component shown in Table 1 is a mass part.

Details of each component shown in Table 1 are as follows.

(A): Maleic anhydride-modified liquid polybutadiene (trade name "Lithene ultra N4-B-10MA" manufactured by Synthomer, number average molecular weight: 8200, viscosity at 25°C: 60 to 90 Pa.sec, acid value: 54 KOHmg/g)

(Ba): Unmodified liquid polybutene (trade name "Nichiyu Polybutene Emawet 0N" manufactured by Nichiyu Co., Ltd., number average molecular weight: 370)

(Bb): Unmodified liquid polybutene (trade name "Nichiyu Polybutene Emawet 015N" manufactured by Nichiyu Co., Ltd., number average molecular weight: 580)

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

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

(C-2): ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., 10 moles of EO)

(D): Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.)

(E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Co., Ltd., hydrogenated resin (alicyclic saturated hydrocarbon resin containing dicyclopentadiene as a monomer component), softening point (nominal value): 104.5 ° C. Weight average molecular weight (nominal): 610)

(2) Fabrication of polarizer

Corona treatment was performed on the surface of a polymethyl methacrylate (PMMA) film having a thickness of 60 μm, and the curable adhesive composition A prepared in (1) above was applied to the corona treatment surface using an adhesive coating device. The obtained coating layer and a polyvinyl alcohol-iodine polarizer having a thickness of 23 μm were laminated using a nip roll to obtain a polarizer having a PMMA film.

Subsequently, corona treatment was performed on the surface of a retardation film [trade name "ZEONOR" manufactured by Nippon Zeon Co., Ltd.] with a thickness of 50 μm containing a cyclic polyolefin-based resin, and the curable adhesive prepared according to the following was applied to the corona-treated surface Composition B was applied using an adhesive application device. The obtained coating layer and the polarizer surface of the polarizer having a PMMA film were laminated using a nip roll to obtain a laminate. From the retardation film side in this laminate, the total amount of light (integrated amount of light irradiation intensity in the wavelength range of 320 to 400 nm) is about 200 mJ / cm 2 (meter: UV Power Puck II manufactured by Fusion UV) The layer of the curable adhesive composition B and the layer of the curable adhesive composition A were cured by irradiating ultraviolet rays (UVB), which are measured values by), to prepare a polarizing plate. In addition, the thickness of the cured layer of curable adhesive composition A was about 10 μm, and the thickness of the cured layer of curable adhesive composition B was 2.5 μm.

Curable adhesive composition B is 1,4 parts by mass of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Celoxide 2021P" manufactured by Daicel Co., Ltd.) 100 parts by mass - 25 parts by mass of butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Co., Ltd.) and 5.6 parts by mass of photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., Ltd.) are added and prepared by mixing.

<Examples 2 to 9, Comparative Example 1>

Curable adhesive composition A was prepared like Example 1 except having changed the compounding quantity of the compounding component as shown in Table 1. In addition, a polarizing plate was produced in the same manner as in Example 1 except that this curable adhesive composition A was used.

<Measurement and evaluation>

(1) Water vapor transmission rate of cured film formed from curable adhesive composition A

The curable adhesive composition A was coated on a PMMA film having a thickness of 60 μm subjected to corona treatment using an adhesive coating device.

An untreated polyethylene terephthalate (PET) film was laminated on the coating layer of the curable adhesive composition A, and bonded using a nip roll. Subsequently, the total integrated light amount (integrated amount of light irradiation intensity in the wavelength range of 320 to 400 nm) is about 200 mJ / cm 2 (meter: measured value by UV Power Puck II manufactured by Fusion UV), ultraviolet rays ( The adhesive layer was cured by irradiation with UVB) to obtain a laminate having a layer configuration of PMMA film/cured adhesive layer/PET film. Then, the PET film was peeled off to obtain a laminate (sample for measuring moisture permeability) having a layer configuration of PMMA film/cured adhesive layer (cured film).

The obtained laminate (sample for measuring moisture permeability) was measured for moisture permeability [g/(m 2 24 hr)] at a temperature of 40°C and a relative humidity of 90% by the cup method specified in JIS Z 0208. In addition, in the measurement, the cured adhesive layer (cured film) in the laminate was made to be in an environment of a temperature of 40°C and a relative humidity of 90%. Further, the laminate was attached to the cup with the cured film facing outward.

The results are shown in the column of "Water Permeability of Laminate" in Table 1. Numerical values in parentheses indicate the thickness (unit: µm) of the cured film of the laminate.

Furthermore, the water vapor transmission rate (J) of the cured film itself at a temperature of 40°C and a relative humidity of 90% was determined based on the following formula using the water vapor transmission rate (Jt) of the obtained laminate.

1/Jt=(1/J)+(1/Jsub)

The PMMA film having a thickness of 60 μm as the base film had a moisture permeability (Jsub) of 70 g/(m 2 24 hr) measured at a temperature of 40° C. and a relative humidity of 90% by the cup method specified in JIS Z 0208.

The results are shown in the column of "Water Permeability of Cured Film" in Table 1. Numerical values in parentheses indicate the thickness (unit: µm) of the cured film.

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

An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the direction of the absorption axis of the polarizer) x 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminate. The obtained laminate was used as a test piece for measuring the peel strength between the polarizer and the PMMA film. The blade of the cutter was inserted between the polarizer and the PMMA film of the test piece, and 30 mm was peeled off from the end in the longitudinal direction, the peeled portion was held by the grip part of the tester, and the lower part of the grip gripped the glass plate. Regarding the test piece in this state, in accordance with JIS K 6854-2: 1999 "Adhesive-Peel Adhesion Strength Test Method-Part 2: 180-degree Peel" in an atmosphere of a temperature of 23 ° C. and a relative humidity of 55%, the grip movement speed is 300 A peeling test was performed at mm/min, the average peeling force over a length of 170 mm excluding 30 mm of the grip portion was determined, and this was taken as the peeling strength between the polarizer and the PMMA film. The results are shown in Table 1. The peeling strength was measured after preparing the polarizing plate and placing it in an environment of a temperature of 23°C and a relative humidity of 50% RH for 24 hours.

In Table 1, "breaking" means that the peeling strength is very large and the PMMA film or polarizer is broken before the film is peeled off. In Comparative Example 1, the adhesiveness between the polarizer and the PMMA film was too weak and the peel strength could not be measured.

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

An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate having the pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the direction of the absorption axis of the polarizer) x 25 mm in width, and the pressure-sensitive adhesive layer was bonded to glass to obtain a laminate. After placing the obtained laminate in a high-temperature, high-humidity environment with a temperature of 80°C and 90% RH for 24 hours, it was placed in an environment with a temperature of 23°C and relative humidity 50% RH for 24 hours. After that, the blade of the cutter was inserted between the polarizer and the PMMA film of the obtained laminate, and 30 mm was peeled off from the end in the longitudinal direction, the peeled portion was held by the grip part of the tester, and the lower part of the grip was held by the glass plate. Regarding the test piece in this state, in accordance with JIS K 6854-2: 1999 "Adhesive-Peel Adhesion Strength Test Method-Part 2: 180-degree Peel" in an atmosphere of a temperature of 23 ° C. and a relative humidity of 55%, the grip movement speed is 300 A peeling test was performed at mm/min, the average peeling force over a length of 170 mm excluding 30 mm of the grip portion was determined, and this was taken as the peeling strength between the polarizer and the PMMA film. The results are shown in Table 1.

<Example 10>

(1) Preparation of Curable Adhesive Composition

The components shown in Table 2 were mixed in the compounding amounts shown in Table 2 to prepare curable adhesive composition C. The unit of the compounding quantity of each component shown in Table 2 is a mass part.

Details of each component shown in Table 2 are as follows.

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

(Bb): Unmodified liquid polybutene (trade name "Nichiyu Polybutene Emawet 015N" manufactured by Nichiyu Co., Ltd., number average molecular weight: 580)

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

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

(C-1c): Stearyl acrylate (trade name "A-S" manufactured by Shin Nakamura Chemical Industry Co., Ltd.)

(C-1d): Lauryl acrylate (trade name "LA" manufactured by Osaka Yuki Chemical Industry Co., Ltd.)

(C-2): ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin-Nakamura Chemical Industry Co., Ltd., 10 moles of EO)

(D): Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.)

(E): Petroleum resin (trade name "T-REZ HA105" manufactured by JXTG Energy Co., Ltd., hydrogenated resin (alicyclic saturated hydrocarbon resin containing dicyclopentadiene as a monomer component), softening point (nominal value): 104.5 ° C. Weight average molecular weight (nominal): 610)

(2) Fabrication of polarizer

Corona treatment was performed on the surface of a polymethyl methacrylate (PMMA) film having a thickness of 60 μm, and the curable adhesive composition C prepared in (1) above was applied to the corona treatment surface using an adhesive coating device. The obtained coating layer and a polyvinyl alcohol-iodine polarizer having a thickness of 23 µm were laminated using a nip roll to obtain a polarizer having a PMMA film.

Subsequently, corona treatment was performed on the surface of a retardation film [trade name "ZEONOR" manufactured by Nippon Zeon Co., Ltd.] with a thickness of 50 μm containing a cyclic polyolefin-based resin, and the curable adhesive prepared according to the following was applied to the corona-treated surface Composition B was applied using an adhesive application device. The obtained coating layer and the polarizer surface of the polarizer having a PMMA film were laminated using a nip roll to obtain a laminate. From the retardation film side in this laminate, the total amount of light (integrated amount of light irradiation intensity in the wavelength range of 320 to 400 nm) is about 200 mJ / cm 2 (meter: UV Power Puck II manufactured by Fusion UV) The layer of the curable adhesive composition B and the layer of the curable adhesive composition C were cured by irradiating ultraviolet (UVB), which is a measured value by), to prepare a polarizing plate. In addition, the thickness of the cured layer of curable adhesive composition C was about 10 μm, and the thickness of the cured layer of curable adhesive composition B was 2.5 μm.

Curable adhesive composition B is 1,4 parts by mass of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Celoxide 2021P" manufactured by Daicel Co., Ltd.) 100 parts by mass - 25 parts by mass of butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Co., Ltd.) and 5.6 parts by mass of photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., Ltd.) are added and prepared by mixing.

<Examples 11 to 12, Comparative Examples 2 to 3>

A curable adhesive composition C was prepared in the same manner as in Example 10 except that the compounding amount of the compounding components was changed as shown in Table 2. In addition, a polarizing plate was produced in the same manner as in Example 10 except that this curable adhesive composition C was used.

<Measurement and evaluation>

(1) Water vapor transmission rate of cured film formed from curable adhesive composition C

The curable adhesive composition C was coated on a PMMA film having a thickness of 60 μm subjected to corona treatment using an adhesive coating device.

An untreated polyethylene terephthalate (PET) film was laminated on the coating layer of the curable adhesive composition C, and bonded using a nip roll. Subsequently, the total integrated light amount (integrated amount of light irradiation intensity in the wavelength range of 320 to 400 nm) is about 200 mJ / cm 2 (meter: measured value by UV Power Puck II manufactured by Fusion UV), ultraviolet rays ( The adhesive layer was cured by irradiation with UVB) to obtain a laminate having a layer configuration of PMMA film/cured adhesive layer/PET film. Then, the PET film was peeled off to obtain a laminate (sample for measuring moisture permeability) having a layer configuration of PMMA film/cured adhesive layer (cured film).

The obtained laminate (sample for measuring moisture permeability) was measured for moisture permeability [g/(m 2 24 hr)] at a temperature of 40°C and a relative humidity of 90% by the cup method specified in JIS Z 0208. In addition, in the measurement, the cured adhesive layer (cured film) in the laminate was made to be in an environment of a temperature of 40°C and a relative humidity of 90%. Further, the laminate was attached to the cup with the cured film facing outward.

The results are shown in the column of "Water Permeability of Laminate" in Table 2. Numerical values in parentheses indicate the thickness (unit: µm) of the cured film of the laminate.

Furthermore, the water vapor transmission rate (J) of the cured film itself at a temperature of 40°C and a relative humidity of 90% was determined based on the following formula using the water vapor transmission rate (Jt) of the obtained laminate.

1/Jt=(1/J)+(1/Jsub)

The PMMA film having a thickness of 60 μm as the base film had a moisture permeability (Jsub) of 70 g/(m 2 24 hr) measured at a temperature of 40° C. and a relative humidity of 90% by the cup method specified in JIS Z 0208.

The results are shown in the column of "Water Permeability of Cured Film" in Table 2. Numerical values in parentheses indicate the thickness (unit: µm) of the cured film.

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

An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with the pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the direction of the absorption axis of the polarizer) x 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminate. The obtained laminate was used as a test piece for measuring the peel strength between the polarizer and the PMMA film. The blade of the cutter was inserted between the polarizer and the PMMA film of the test piece, and 30 mm was peeled off from the end in the longitudinal direction, the peeled portion was held by the grip part of the tester, and the lower part of the grip gripped the glass plate. Regarding the test piece in this state, in accordance with JIS K 6854-2: 1999 "Adhesive-Peel Adhesion Strength Test Method-Part 2: 180-degree Peel" in an atmosphere of a temperature of 23 ° C. and a relative humidity of 55%, the grip movement speed is 300 A peeling test was performed at mm/min, the average peeling force over a length of 170 mm excluding 30 mm of the grip portion was determined, and this was taken as the peeling strength between the polarizer and the PMMA film. The results are shown in Table 2. The peeling strength was measured after preparing the polarizing plate and placing it in an environment of a temperature of 23°C and a relative humidity of 50% RH for 24 hours.

In Table 2, "breaking" means that the peeling strength is very large and the PMMA film or polarizer is broken before the film is peeled off.

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

An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate having the pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the direction of the absorption axis of the polarizer) x 25 mm in width, and the pressure-sensitive adhesive layer was bonded to glass to obtain a laminate. After placing the obtained laminate in a high-temperature, high-humidity environment with a temperature of 80°C and 90% RH for 24 hours, it was placed in an environment with a temperature of 23°C and relative humidity 50% RH for 24 hours. After that, the blade of the cutter was inserted between the polarizer and the PMMA film of the obtained laminate, and 30 mm was peeled off from the end in the longitudinal direction, the peeled portion was held by the grip part of the tester, and the lower part of the grip was held by the glass plate. Regarding the test piece in this state, in accordance with JIS K 6854-2: 1999 "Adhesive-Peel Adhesion Strength Test Method-Part 2: 180-degree Peel" in an atmosphere of a temperature of 23 ° C. and a relative humidity of 55%, the grip movement speed is 300 A peeling test was performed at mm/min, the average peeling force over a length of 170 mm excluding 30 mm of the grip portion was determined, and this was used as the peeling strength between the polarizer and the PMMA film. The results are shown in Table 2.

10 1st thermoplastic resin film, 15 1st adhesive layer, 20 2nd thermoplastic resin film, 25 2nd adhesive layer, 30 polarizer.

Claims (12)

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 content of the maleic anhydride-modified compound (A) according to claim 1, wherein the content of the maleic anhydride-modified compound (A) and unmodified polybutene (B) is 40% by mass or more and 90% by mass in 100% by mass of the total amount. The following curable adhesive composition. The curable adhesive composition according to claim 1 or 2, wherein the (meth)acrylate compound (C) comprises a monofunctional (meth)acrylate compound (C-1). The curable adhesive composition according to claim 3, wherein the content of the monofunctional (meth)acrylate compound (C-1) is 60% by mass or more and 99% by mass or less with respect to 100% by mass of the (meth)acrylate compound (C). . The monofunctional (meth)acrylate compound (C-1) according to claim 3 or 4 is at least one selected from the group consisting of alicyclic alkyl (meth)acrylate compounds and aromatic (meth)acrylate compounds. A curable adhesive composition comprising one type of compound. The monofunctional (meth)acrylate compound (C-1) according to any one of claims 3 to 5 is an alicyclic alkyl (meth)acrylate compound and straight or branched chain C ₄ -C ₃₆ Curable adhesive composition comprising an alkyl (meth) acrylate compound. The method of claim 6, wherein the content of the alicyclic alkyl (meth) acrylate compound, the alicyclic alkyl (meth) acrylate compound and the linear or branched C ₄ -C ₃₆ alkyl (meth) acrylate compound Curable adhesive composition which is 30 mass % or more and 80 mass % or less in 100 mass % of total amounts. The curable adhesive composition according to any one of claims 1 to 7, further comprising a petroleum resin (E). The curable adhesive composition according to any one of claims 1 to 8, wherein the maleic anhydride-modified compound (A) contains a maleic anhydride-modified polymer (A-1). The cured film according to any one of claims 1 to 9, wherein the cured film having a thickness of 10 μm made of the curable adhesive composition has a water vapor transmission rate of 400 g/(m 2 24 hr) or less at a temperature of 40° C. and a relative humidity of 90%. Curable adhesive composition having. A polarizing plate comprising a polarizer, an adhesive layer and a thermoplastic resin film in this order,
The adhesive layer is a polarizing plate that is a cured product layer of the curable adhesive composition according to any one of claims 1 to 10. The polarizing plate of claim 11, wherein the thermoplastic resin film is a (meth)acrylic resin film.