JP2022104566A - Curable adhesive composition and polarizing plate - Google Patents

Abstract

To provide a curable adhesive composition suitable for bonding a polarizer and a thermoplastic resin film together, and a polarizing plate including a polarizer, an adhesive layer and a thermoplastic resin film in this order and having good adhesion between the polarizer and the thermoplastic resin film.SOLUTION: There are provided: a curable adhesive composition containing a maleic anhydride-modified compound (A), a (meth)acrylate compound (B) and a photopolymerization initiator (C), wherein the (meth)acrylate compound (B) contains a monofunctional (meth)acrylate compound (B-1), and the monofunctional (meth)acrylate compound (B-1) contains an alicyclic alkyl (meth)acrylate compound and a linear or branched C4-C36 alkyl (meth)acrylate compound; and a polarizing plate including a polarizer, an adhesive layer and a thermoplastic resin film in this order, the adhesive layer being a cured product layer of the curable adhesive composition.SELECTED DRAWING: Figure 1

Description

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

A polarizing plate widely used in an image display device such as a liquid crystal display device or an organic EL display device usually has a structure in which a thermoplastic resin film such as a protective film is bonded to one side or both sides of a polarizing element. An adhesive is usually used for bonding the splitter and the thermoplastic resin film. As the adhesive, an active energy ray-curable adhesive and a water-based adhesive are known [for example, Japanese Patent Application Laid-Open No. 2009-008660 (Patent Document 1)].

Japanese Unexamined Patent Publication No. 2009-008660

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

The present invention provides the curable adhesive composition and the polarizing plate shown below.
[1] Contains maleic anhydride-modified compound (A), (meth) acrylate compound (B) and photopolymerization initiator (C).
The (meth) acrylate compound (B) contains a monofunctional (meth) acrylate compound (B-1).
The monofunctional (meth) acrylate compound (B-1) is a curable adhesive composition containing an alicyclic alkyl (meth) acrylate compound and a linear or branched _C4 -C ₃₆ alkyl (meth) acrylate compound. ..
[2] The content of the monofunctional (meth) acrylate compound (B-1) is 60% by mass or more and 99% by mass or less in 100% by mass of the (meth) acrylate compound (B) according to [1]. Curable adhesive composition.
[3] 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 _C4 -C ₃₆ alkyl (meth) acrylate compound. The curable adhesive composition according to [1] or [2], which is 5% by mass or more and 80% by mass or less in 100% by mass.
[4] The curable adhesive composition according to any one of [1] to [3], which further comprises unmodified polybutadiene (D).
[5] When the content of the maleic anhydride-modified compound (A) is 40% by mass or more and 90% by mass or less in the total amount of 100% by mass of the maleic anhydride-modified compound (A) and the unmodified polybutadiene (B). The curable adhesive composition according to [4].
[6] The curable adhesive composition according to any one of [1] to [5], which further comprises a petroleum resin (E).
[7] The curable adhesive composition according to any one of [1] to [6], wherein the maleic anhydride-modified compound (A) contains a maleic anhydride-modified polymer (A-1).
[8] The cured film having a thickness of 10 μm made of the curable adhesive composition has a moisture permeability of 400 g / ( ^m 2.24 hr) or less at a temperature of 40 ° C. and a relative humidity of 90% [1] to [7]. The curable adhesive composition according to any one.
[9] A polarizing plate containing a polarizing element, an adhesive layer, and a thermoplastic resin film in this order.
The adhesive layer is a polarizing plate which is a cured product layer of the curable adhesive composition according to any one of [1] to [8].
[10] The polarizing plate according to [9], wherein the thermoplastic resin film is a (meth) acrylic resin film.

A curable adhesive composition suitable for bonding a decoder and a thermoplastic resin film, and a polarizing plate including a polarizing element, an adhesive layer, and a thermoplastic resin film in this order, wherein the substituent and the thermoplastic resin are used. It is possible to provide a polarizing plate having good adhesion to a film.

It is a schematic sectional drawing which shows an example of the layer structure of the polarizing plate which concerns on this invention. It is a schematic sectional drawing which shows another example of the layer structure of the polarizing plate which concerns on this invention.

<Curable adhesive composition>
The curable adhesive composition according to the present invention (hereinafter, also referred to as “adhesive composition”) is suitable for adhering a thermoplastic resin film, for example, a thermoplastic resin film and another thermoplastic resin film (hereinafter, also referred to as “adhesive composition”). Or it can be used for bonding with a layer). An example of application of the adhesive composition according to the present invention is for a polarizing plate, that is, it can be used for producing a polarizing plate. More specifically, the adhesive composition according to the present invention is useful as an adhesive composition used for bonding a polarizing element and a thermoplastic resin film.

As used herein, the polarizing plate refers to a laminated optical film including a polarizing element and a thermoplastic resin film laminated on one side or both sides thereof. In the polarizing plate, the polarizing element and the thermoplastic resin film are laminated via an adhesive layer. The adhesive layer is a layer formed from the adhesive composition, and more specifically, a cured product layer of the adhesive composition.
The polarizing plate may include a polarizing element and a film or layer other than the above-mentioned thermoplastic resin film.

The adhesive composition is a curable adhesive composition containing a maleic anhydride-modified compound (A), a (meth) acrylate compound (B) and a photopolymerization initiator (C). The adhesive composition may contain components other than these.
Unless otherwise specified, the compounds exemplified as the components contained or may be contained in the adhesive composition in the present specification may be used alone or in combination of two or more.

[1] Maleic anhydride-modified compound (A)
The maleic anhydride-modified compound (A) is a compound containing a maleic anhydride structure in the 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 compound (A).
Examples of the maleic anhydride-modified compound (A) include a maleic anhydride-modified polymer (A-1).

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).

（＊は主鎖への結合手を表す。） The above-mentioned maleic anhydride structure means the following structure.

(* Indicates a bond to the main chain.)

In the maleic anhydride-modified polymer (A-1), the polymer to be modified with maleic anhydride includes a diene polymer, a polyolefin polymer, a (meth) acrylic polymer, a polyester polymer, and a polystyrene-based polymer. Examples thereof include coalescing and polyether polymers. These polymers may be homopolymers composed of one kind of monomer, or may be copolymers composed of two or more kinds of monomers.

As used herein, the term "(meth) acrylic" refers to at least one selected from the group consisting of acrylic and methacrylic. The same applies to the notations such as "(meth) acryloyl" and "(meth) acrylate".

The maleic anhydride-modified polymer (A-1) is preferably maleic anhydride-modified polybutadiene. Each of these polymers may be a homopolymer or a copolymer. When it is a copolymer, the copolymerization monomer is, for example, an olefin monomer.

The polybutadiene may be 1,4-polybutadiene, 1,2-polybutadiene, a structural unit formed by 1,4-addition and a structural unit formed by 1,2-addition. May include both. The 1,4-addition may be a trans addition or a cis addition.

The maleic anhydride-modified polymer (A-1) is preferably liquid because it can prepare a solvent-free adhesive composition having good adhesive ability. Liquid means that it exhibits fluidity at a temperature of 25 ° C.
The viscosity of the liquid maleic anhydride-modified polymer (A-1) at 25 ° C. is usually 1 Pa · sec or more and 1300 Pa · sec or less, preferably 10 Pa, from the viewpoint of obtaining an adhesive composition having good coatability. It is sec or more and 1000 Pa · sec or less, more preferably 15 Pa · sec or more and 700 Pa · sec or less, and further preferably 15 Pa · sec or more and 150 Pa · sec or less.

The number average molecular weight of the maleic anhydride-modified polymer (A-1) is usually 500 or more and 15,000 or less, preferably 600 or more and 12,000 or less, and more preferably 700 or more and 10,000 or less from the viewpoint of viscosity and coatability. It is more preferably 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 KOH mg / g or more and 200 KOH mg / g or less, which is preferable from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer). Is 15 KOH mg / g or more and 150 KOH mg / g or less, more preferably 20 KOH mg / g or more and 100 KOH mg / g or less, and further preferably 45 KOH mg / g or more and 80 KOH mg / g or less. The use of the maleic anhydride-modified polymer (A-1) having an acid value in the above range is advantageous in enhancing the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and in particular, it is advantageous. When a polyvinyl alcohol-based polarizing element is used as the polarizing element, it is advantageous in providing an adhesive composition having high adhesion between the polyvinyl alcohol-based polarizing element 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 to the thermoplastic resin film (or layer). From the viewpoint of the adhesive ability of the composition, particularly from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizing element and the thermoplastic resin film when a polyvinyl alcohol-based polarizing element is used as the polarizing element, it is preferably 5% by mass or more. It is 35% by mass or less, more preferably 10% by mass or more and 30% by mass or less.

[2] (Meta) acrylate compound (B)
The (meth) acrylate compound (B) is a radically polymerizable compound having one or more (meth) acryloyloxy groups in the molecule.
The adhesive composition may contain one or more (meth) acrylate compounds (B).

The (meth) acrylate compound (B) includes a monofunctional (meth) acrylate compound (B-1) having one (meth) acryloyloxy group in the molecule and two (meth) acryloyloxy groups in the molecule. Examples thereof include a bifunctional (meth) acrylate compound (B-2) having the above, and a polyfunctional (meth) acrylate compound (B-3) having three or more (meth) acryloyloxy groups in the molecule.
The (meth) acrylate compound (B) is a monofunctional (meth) acrylate compound (B-1), a bifunctional (meth) acrylate compound (B-2) and a polyfunctional (meth) acrylate compound (B-3). Each can be contained in one kind or two or more kinds.

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

Other examples of the monofunctional (meth) acrylate compound (B-1) include, for example,
Aralkyl (meth) acrylates such as benzyl (meth) acrylates, 2-phenoxyethyl (meth) acrylates, phenoxyethylene glycol (meth) acrylates, 2-hydroxy-3-phenoxypropyl (meth) acrylates, ethoxylated-o- An aromatic (meth) acrylate compound in which the group bonded to -O- of the ester bond (-C (= O) -O-) such as phenoxy (meth) acrylate such as phenylphenol (meth) acrylate contains an aromatic ring;
Ester bond (-C (=) of cyclohexyl (meth) acrylate, cyclohexylmethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, isobornyl (meth) acrylate, etc. An alicyclic alkyl (meth) acrylate compound in which the group bonded to —O— of O) —O—) contains an alicyclic ring;
Aminoalkyl (meth) acrylate compounds such as N, N-dimethylaminoethyl (meth) acrylate;
A group that binds to -O- of an ester bond (-C (= O) -O-) such as dicyclopentenyloxyethyl (meth) acrylate, ethyl carbitol (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate Examples of the (meth) acrylate compound containing an ether bond include those other than the above.

Still another example of the monofunctional (meth) acrylate compound (B-1) is, for example,
2-Hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, trimethylolpropane mono (meth) A (meth) acrylate compound in which the group bonded to -O- of an ester bond (-C (= O) -O-) contains a hydroxyl group, such as acrylate and pentaerythritol mono (meth) acrylate;
2-Carboxyl (meth) acrylate, ω-carboxy-polycaprolactone (n≈2) mono (meth) acrylate, 1- [2- (meth) acryloyloxyethyl] phthalic acid, 1- [2- (meth) acryloyl Oxyethyl] hexahydrophthalic acid, 1- [2- (meth) acryloyloxyethyl] succinic acid, 4- [2- (meth) acryloyloxyethyl] trimellitic acid, N- (meth) acryloyloxy-N', Examples thereof include (meth) acrylate compounds in which the group bonded to -O- of the ester bond (-C (= O) -O-) contains a carboxyl group, such as N'-dicarboxymethyl-p-phenylenediamine.

Examples of the bifunctional (meth) acrylate compound (B-2) include alkylene glycol di (meth) acrylate, polyoxyalkylene glycol di (meth) acrylate, halogen-substituted alkylene glycol di (meth) acrylate, and aliphatic polyol di. Di (meth) acrylate, di (meth) acrylate of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylate of dioxane glycol or dioxane dialkanol, di (meth) of alkylene oxide adduct of bisphenol A or bisphenol F. ) Acrylate, bisphenol A or bisphenol F epoxy di (meth) acrylate and the like can be mentioned.

More specific examples of the bifunctional (meth) acrylate compound (B-2) include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, and 1,4-butanediol di (). Meta) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethyl propandi (meth) acrylate, pentaerythritol di (meth) Meta) 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 (Meta) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicone di (meth) acrylate, hydroxypivalate neopentyl glycol ester di (meth) acrylate, 2,2-bis [ 4- (meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyldi (meth) acrylate, tricyclodecanedimethanol Di (meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (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, ethoxy Di (meth) acrylate of 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 (B-2) preferably has at least one alicyclic skeleton or at least one aromatic ring in the molecule, more preferably at least one aromatic ring.

The bifunctional (meth) acrylate (B-2) has moisture permeability of the cured product, compatibility with the maleic anhydride-modified compound (A), and adhesion with a thermoplastic resin film (particularly (meth) acrylic resin film). From the viewpoint of the above, it is preferable to include the compound represented by the following formula, and more preferably the compound represented by the following formula.

(In the formula, R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group, and X represents ethylene oxide (-C ₂ H ₄ O-) or propylene oxide (-C ₃ H ₆ O-). , N represents an integer of 1 to 20, and m represents an integer of 1 to 20.)
X is preferably ethylene oxide, and the average of the total of m and n is preferably 2 to 20, more preferably 3 to 15, and even more preferably 4 to 13. ..

Examples of the polyfunctional (meth) acrylate compound (B-3) having three or more (meth) acryloyloxy groups in the molecule include glycerintri (meth) acrylate, alkoxylated glycerintri (meth) acrylate, and trimethyl propantri. (Meta) Acrylate, Ditrimethylol Propantri (Meta) Acrylate, Ditrimethylol Propanetetra (Meta) Acrylate, Pentaerythritol Tri (Meta) Acrylate, Pentaerythritol Tetra (Meta) Acrylate, Dipentaerythritol Tetra (Meta) Acrylate, Dipenta Poly (meth) acrylate of trifunctional or higher functional aliphatic polyols such as erythritol penta (meth) acrylate and dipenta erythritol hexa (meth) acrylate;
Poly (meth) acrylates of trifunctional or higher functional halogen-substituted polyols;
Tri (meth) acrylate of glycerin alkylene oxide adduct;
Tri (meth) acrylate of alkylene oxide adduct of trimethylolpropane;
1,1,1-Tris [(meth) acryloyloxyethoxyethoxy] propane;
Examples thereof include tris (hydroxyethyl) isocyanurate tri (meth) acrylate.

From the viewpoint of reducing the viscosity of the adhesive composition, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and from the viewpoint of the wet and heat durability of the polarizing plate using the polyvinyl alcohol-based polarizing element, that is, The (meth) acrylate compound (B) is monofunctional from the viewpoint of providing a polarizing plate having good adhesion between the polyvinyl alcohol-based polarizing element and the thermoplastic resin film even after being placed in a moist heat environment. Contains (meth) acrylate compound (B-1).

When the total amount of the (meth) acrylate compound (B) is 100% by mass, the content of the monofunctional (meth) acrylate compound (B-1) is usually 60% by mass or more, and the thermoplastic resin film (or layer) is formed. ), And more preferably 70% by mass or more, more preferably 80% by mass or more, from the viewpoint of the adhesive ability of the adhesive composition and the wet and heat durability of the polarizing plate using the polyvinyl alcohol-based polarizing element. ..

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

When the content of the monofunctional (meth) acrylate compound (B-1) is less than 100% by mass, the balance of the (meth) acrylate compound (B) is the bifunctional (meth) acrylate compound (B-2) and /. Alternatively, it is a polyfunctional (meth) acrylate compound (B-3), and preferably contains a bifunctional (meth) acrylate compound (B-2).

From the viewpoint of reducing the viscosity of the adhesive composition, the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), and the moist heat durability of the polarizing plate using a polyvinyl alcohol-based polarizing element. The monofunctional (meth) acrylate compound (B-1) contains an alicyclic alkyl (meth) acrylate compound and a linear or branched _C4 -C ₃₆ alkyl (meth) acrylate compound, and the alicyclic alkyl (meth). ) It is preferably composed of an acrylate compound and a linear or branched _C4 -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, nonyl (meth) acrylate, and decyl. (Meta) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isomyristyl. Examples thereof include (meth) acrylate, behenyl (meth) acrylate, and tetradecyl (meth) acrylate.

From the viewpoint of the wet heat durability of the polarizing plate using a polyvinyl alcohol-based polarizing element, the carbon number of the linear or branched _C4 - _C36 alkyl (meth) acrylate compound is preferably 8 or more, more preferably 8 or more. It is 10 or more, and particularly preferably 12 or more. The carbon number may be 24 or less, or may be 22 or less.

The content of the alicyclic alkyl (meth) acrylate compound is determined from the viewpoint of the adhesive ability of the adhesive composition and the moist heat durability of the polarizing plate using the polyvinyl alcohol-based polarizing element. In a total amount of 100% by mass of the compound and the linear or branched _C4 -C ₃₆ alkyl (meth) acrylate compound, it is preferably 5% by mass or more and 80% by mass or less, and more preferably 10% by mass or more and 70% by mass. It is more preferably 15% by mass or more and 60% by mass or less, still more preferably 20% by mass or more and 50% by mass or less.

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

[3] Photopolymerization Initiator (C)
The photopolymerization initiator (C) is not particularly limited as long as it is a compound that can initiate the polymerization of the (meth) acrylate compound (B) by generating active radicals, acids and the like by the action of light.
The adhesive composition may contain only one type of photopolymerization initiator (C), or may contain two or more types.

The photopolymerization initiator (C) is not particularly limited, and examples thereof include oxime compounds such as O-acyloxime compounds, alkylphenone compounds, and acylphosphine oxide compounds.

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

Examples of the O-acyloxym compound include N-benzoyloxy-1- (4-phenylsulfanylphenyl) butane-1-on-2-imine and N-benzoyloxy-1- (4-phenylsulfanylphenyl) octane-1-. On-2-imin, N-benzoyloxy-1- (4-phenylsulfanylphenyl) -3-cyclopentylpropane-1-on-2-imin, N-acetoxy-1- [9-ethyl-6- (2-ethyl-6- (2-) Methylbenzoyl) -9H-carbazole-3-yl] ethane-1-imine, N-acetoxy-1- [9-ethyl-6- {2-methyl-4- (3,3-dimethyl-2,4-di) Oxacyclopentanylmethyloxy) benzoyl} -9H-carbazole-3-yl] ethane-1-imine, N-acetoxy-1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-3 Il] -3-cyclopentylpropane-1-imine, N-benzoyloxy-1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl] -3-cyclopentylpropane-1-one -2-Imin, N-acetyloxy-1- [4- (2-hydroxyethyloxy) phenylsulfanylphenyl] Propane-1-on-2-imin, N-acetyloxy-1- [4- (1-methyl) -2-Methylethoxy) -2-methylphenyl] -1- (9-ethyl-6-nitro-9H-carbazole-3-yl) methane-1-imine and the like can be mentioned.
Commercially available products such as Irgacure (trade name) OXE01, OXE02, OXE03 (above, manufactured by BASF), N-1919, NCI-930, NCI-831 (above, manufactured by ADEKA) may 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). In these partial structures, the benzene ring may have a substituent.

Examples of the compound having a structure represented by the formula (d4) include 2-methyl-2-morpholino-1- (4-methylsulfanylphenyl) propan-1-one and 2-dimethylamino-1- (4-morpholinophenyl). ) -2-Benzylbutane-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] butane-1-one, etc. Be done.
Commercially available products such as Omnirad (trade name) 369, 907, and 379 (all manufactured by IGM Resins B.V.) may be used.

Examples of the compound having a structure represented by the formula (d5) include 2-hydroxy-2-methyl-1-phenylpropan-1-one and 2-hydroxy-2-methyl-1- [4- (2-hydroxyethoxy). ) Phenyl] Propane-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1- (4-isopropenylphenyl) propan-1-one oligomer, α, α-diethoxyacetophenone, benzyl Examples include dimethyl ketal and the like.
Commercially available products such as Omnirad (trade name) 184 (manufactured by IGM Resins B.V.) may be used.

Examples of the acylphosphine oxide compound include phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (for example, trade name "Omnirad 819" (manufactured by IGM Resins VV)) and 2,4,6-trimethylbenzoyl. Examples thereof include diphenylphosphine oxide.

As a further example of the photopolymerization initiator (C),
Benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether;
Benzophenone, o-Methyl benzoyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4 Benzophenone compounds such as 6-trimethylbenzophenone, 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, 2-ethyl-9,10-diethoxyanthracene;
Quinone compounds such as 9,10-phenanthrenquinone, 2-ethylanthraquinone, camphorquinone;
Examples thereof include benzyl, methyl phenylglyoxylate, and titanocene compounds.

When the total amount of the adhesive composition is 100% by mass, the content of the photopolymerization initiator (C) is usually 0.1% by mass or more and 20% by mass or less, and from the viewpoint of curability of the adhesive composition and From the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), it is preferably 0.5% by mass or more and 15% by mass or less, and 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 (B) is 100 parts by mass, the content of the photopolymerization initiator (C) is usually 0.1 parts by mass or more and 30 parts by mass or less, and the adhesive composition is cured. From the viewpoint of properties and the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), it is preferably 0.5 parts by mass or more and 20 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less. Is.

[4] Unmodified polybutadiene (D)
The adhesive composition can further include unmodified polybutadiene (D). Further inclusion of the unmodified polybutadiene (D) in the adhesive composition may be advantageous from the viewpoint of the adhesive ability of the adhesive composition and the moist heat durability of the polarizing plate using the polyvinyl alcohol-based polarizing element.

Unmodified polybutadiene (D) is unmodified polybutadiene, which is a polymer obtained by addition polymerization of 1,3-butadiene. Not modified means that the side chain does not contain reactive or polar groups. The adhesive composition may contain one type of unmodified polybutadiene or may contain two or more types of unmodified polybutadiene.

The unmodified polybutadiene (D) may be 1,4-polybutadiene, 1,2-polybutadiene, or a structural unit (1,4-addition unit) formed by 1,4-addition. ) And the structural units formed by 1,2-addition (1,2-addition units) may be included. The 1,4-addition may be a trans addition or a cis addition.
When unmodified polybutadiene (D) contains both 1,4-addition units and 1,2-addition units, their content is in molar ratio, usually 1,4-addition units / 1,2-addition units. = 50 to 95/50 to 5, preferably 70 to 90/30 to 10, and more preferably 75 to 90/25 to 10.

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

The unmodified polybutadiene (D) is preferably liquid because it can prepare a solvent-free adhesive composition having good adhesive ability. Liquid means that it exhibits fluidity at a temperature of 25 ° C.
The viscosity of the liquid unmodified polybutadiene (D) at 25 ° C. is preferably 0.1 Pa · sec or more and 100 Pa · sec or less, and more preferably 0. It is 2 Pa · sec or more and 50 Pa · sec or less, and more preferably 0.5 Pa · sec or more and 10 Pa · sec or less.

The number average molecular weight of the unmodified polybutadiene (D) is usually 500 or more and 15,000 or less, preferably 600 or more and 10,000 or less, more preferably 700 or more and 9000 or less, still more preferably, from the viewpoint of viscosity and coatability. Is 1000 or more and 5000 or less.
The number average molecular weight of unmodified polybutadiene (D) can be measured as a standard polystyrene conversion value by GPC.

When the adhesive composition contains unmodified polybutadiene (D), the content of unmodified polybutadiene (D) is usually 1% by mass or more and 20% by mass or less when the total amount of the adhesive composition is 100% by mass. There is, from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), particularly when a polyvinyl alcohol-based decoder is used as the polarizing element, between the polyvinyl alcohol-based polarizing element and the thermoplastic resin film. From the viewpoint of enhancing the adhesiveness, it is preferably 2% by mass or more and 18% by mass or less, and more preferably 3% by mass or more and 15% by mass or less.

When the adhesive composition contains unmodified polybutadiene (D), the total amount of the maleic anhydride-modified compound (A) and the unmodified polybutadiene (D) is usually set when the total amount of the adhesive composition is 100% by mass. 4% by mass or more and 60% by mass or less, and from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), particularly when a polyvinyl alcohol-based polarizing element is used as the polarizing element, the polyvinyl alcohol-based polarizing element From the viewpoint of enhancing the adhesion between the and the thermoplastic resin film, it is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and further preferably 15% by mass or more. It is 30% by mass or less.

When the adhesive composition contains the unmodified polybutadiene (D), the unmodified polybutadiene (when the total amount of the anhydrous maleic acid-modified compound (A) and the unmodified polybutadiene (D) in the adhesive composition is 100% by mass, the unmodified polybutadiene ( The content of D) is usually 5% by mass or more and 65% by mass or less, and from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), in particular, a polyvinyl alcohol-based polarizing element is used as the substituent. In some cases, it is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, from the viewpoint of enhancing the adhesion between the polyvinyl alcohol-based polarizing element and the thermoplastic resin film. ..

When the adhesive composition contains unmodified polybutadiene (D), male anhydride-modified when the total amount of the anhydrous maleic acid-modified compound (A) and the unmodified polybutadiene (D) in the adhesive composition is 100% by mass. The content of the compound (A) is determined from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), particularly when a polyvinyl alcohol-based polarizing element is used as the polarizing element, the polyvinyl alcohol-based polarizing element and the heat. From the viewpoint of enhancing the adhesion with the plastic resin film, it is preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 80% by mass or less.

[5] Adhesive imparting agent The adhesive composition may further contain a tackifier. The tackifier resin is not particularly limited and may be appropriately selected from known ones. For example, a rosin derivative (for example, rosin, polymerized rosin, hydrogenated rosin), a terpene-based resin (for example, terpene resin, aromatic modification) can be appropriately selected. (Terpene resin, terpene phenol resin, hydrogenated terpene resin), petroleum resin, phenol-based resin, xylene-based resin and the like can be mentioned.

Above all, it is preferable that the adhesive composition further contains the petroleum resin (E). By further containing the petroleum resin (E) in the adhesive composition, the adhesiveness can be improved and the moisture permeability of the cured film formed from the adhesive composition can be reduced.
The adhesive composition capable of forming a cured film having low moisture permeability is suitable for applications in which it is required to suppress the inflow and outflow of water 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 polarizing element via an adhesive layer or an image display panel including the polarizing plate, if the adhesive layer has low moisture permeability, the moisture content is reduced. It is possible to suppress curl (warp) of the polarizing plate or the image display panel caused by entering and exiting.
Further inclusion of the petroleum resin (E) in the adhesive composition may be advantageous in improving the adhesion between the substituent and the thermoplastic resin film.

Examples of the petroleum resin (E) include aromatic petroleum resin, aliphatic petroleum resin, cyclic aliphatic petroleum resin, aliphatic / aromatic petroleum resin, and kumaron resin. Further, hydrogenated ones of these resins and the like can also be mentioned.
The aromatic petroleum resin is a resin containing one or more structural units derived from aromatic hydrocarbons, and may be hydrogenated from the resin or modified from the resin.

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 a hydrogenated resin or a modified resin.
The C9-based petroleum resin may be a resin obtained by copolymerizing a C9 fraction with another monomer component, or may be a hydrogenated resin or a modified resin. good. Examples of other monomer components include C5 fraction.

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 methyl indene.
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 fraction, a hydrogenated C5-based petroleum resin, or a modified resin. good. Further, it may be an alicyclic hydrocarbon resin obtained by polymerizing the C5 fraction after cyclization dimerization. Examples of the alicyclic hydrocarbon-based resin include polymers containing a structural unit derived from dicyclopentadiene.

The weight average molecular weight of the petroleum resin (E) is usually 500 or more and 10,000 or less, from the viewpoint of reducing the moisture permeability of the cured film formed from 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 500 or more and 7,000 or less, more preferably 600 or more and 5000 or less, and further preferably 600 or more and 3000 or less.
The weight average molecular weight of the petroleum resin (E) can be measured as a standard polystyrene-equivalent value by GPC.

When the adhesive composition contains the petroleum resin (E) and the total amount of the adhesive composition is 100% by mass, the content of the petroleum resin (E) is the content of the cured film formed from the adhesive composition. From the viewpoint of reducing moisture permeability and from the viewpoint of the adhesive ability of the adhesive composition to the thermoplastic resin film (or layer), particularly when a polyvinyl alcohol-based polarizing element is used as the polarizing element, the polyvinyl alcohol-based polarizing element and heat are used. From the viewpoint of enhancing the adhesion with the plastic resin film, it is preferably 20% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 65% by mass or less.

The moisture permeability of the cured film formed from the adhesive composition is preferably low. A cured film having a thickness of 10 μm made of an adhesive composition has a moisture permeation measured at a temperature of 40 ° C. and a relative humidity of 90% by the cup method specified in JIS Z 0208, 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 water permeability is usually 1 g / ( ^m 2.24 hr) or more, for example, 5 g / ( ^m 2.24 hr) or more.

The moisture permeability J of the cured film made of the adhesive composition specifically prepares a laminated body formed by forming the cured film on a base film having a known moisture permeability, and determines the moisture permeability of the laminated body. It can be measured by the above method and obtained based on the following formula using the measurement results.
1 / Jt = (1 / J) + (1 / Jsub)
In the above formula, Jt is the moisture permeability of the laminated body, and Jsub is the moisture permeability of the base film. As the base film, the same film as the thermoplastic resin film described later can be used. When measuring the moisture permeability of the laminate according to JIS Z 0208, the laminate is attached to the cup with the cured film facing outward.

With respect to the laminate, for example, when a (meth) acrylic resin film having a thickness of 60 μm is used as the base film, the (meth) acrylic resin film and a cured film having a thickness of 10 μm made of an adhesive composition are laminated. The body has a water permeability measured by the cup method specified in JIS Z 0208 under the conditions of a temperature of 40 ° C. and a relative humidity of 90%, preferably 55 g / ( ^m 2.24 hr) or less, more preferably. It is 50 g / ( ^m 2.24 hr) or less. The water permeability is usually 1 g / ( ^m 2.24 hr) or more, for example, 5 g / ( ^m 2.24 hr) or more.

[6] Other components The adhesive composition may contain other components other than the above.
Examples of other components include curable components other than the (meth) acrylate compound (C), cross-linking agents; additives such as coupling agents, antioxidants, ultraviolet absorbers, and heat stabilizers.

[7] Viscosity of Adhesive Composition The viscosity of the adhesive composition at 25 ° C. is preferably 10,000 mPa · sec or less, more preferably 2 mPa · sec or more and 7,000 mPa · sec or less, and 300 mPa · sec or more and 5000 mPa or more. -It is more preferably sec or less.
The viscosity of the adhesive composition at 25 ° C. can be measured by an E-type viscometer.

<Polarizer>
The adhesive composition according to the present invention is suitable for adhering a thermoplastic resin film, and can be used, for example, for laminating a thermoplastic resin film and another thermoplastic resin film (or layer). An example of application of the adhesive composition according to the present invention is for a polarizing plate, that is, it can be used for producing a polarizing plate. More specifically, the adhesive composition according to the present invention is useful as an adhesive composition used for bonding a polarizing element and a thermoplastic resin film such as a protective film laminated on the polarizing element.

The polarizing plate according to the present invention includes a polarizing element 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 cured product layer of the adhesive composition.

In the polarizing plate according to the present invention, since the polarizing element and the thermoplastic resin film are adhered to each other by using the above-mentioned adhesive composition, the adhesion between the polarizing element and the thermoplastic resin film can be improved, and the adhesion can be improved. , The wet and 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 polarizing element 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 an image display device such as a liquid crystal display device and an organic EL device.

[1] Structure 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 can include the polarizing element 30, the first adhesive layer 15, and the first thermoplastic resin film 10 in this order, that is, the polarizing element 30 and its plurality. It can include a first thermoplastic resin film 10 laminated and bonded via the first adhesive layer 15 on one surface.
It is preferable that the first adhesive layer 15 and the first thermoplastic resin film 10 are in direct contact with each other.
It is preferable that the splitter 30 and the first adhesive layer 15 are in direct contact with each other.

Further, as shown in FIG. 2, the polarizing plate according to the present invention includes a polarizing element 30, a first thermoplastic resin film 10 laminated and bonded to one surface thereof via a first adhesive layer 15, and a polarizing plate. The other surface of the child 30 may include a second thermoplastic resin film 20 laminated and bonded via the second adhesive layer 25.
It is preferable that the first adhesive layer 15 and the first thermoplastic resin film 10 are in direct contact with each other.
It is preferable that the splitter 30 and the first adhesive layer 15 are in direct contact with each other.
It is preferable that the second adhesive layer 25 and the second thermoplastic resin film 20 are in direct contact with each other.
It is preferable that the splitter 30 and the second adhesive layer 25 are in direct contact with each other.

When the polarizing plate has the first adhesive layer 15 and the second adhesive layer 25, either one may be formed from the adhesive composition according to the present invention, or both adhesive layers may be the present. It may be formed from the adhesive composition according to the invention. The adhesive layer formed from the adhesive composition according to the present invention is preferably an adhesive layer on the visual side (an adhesive layer far from the adhesive layer described later).
When 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.

Not limited to the examples of FIGS. 1 and 2, the polarizing plate according to the present invention may include a layer (or film) other than the above. Examples of the other layer include 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 polarizing element 30; and a separate layer laminated on the outer surface of the pressure-sensitive adhesive layer. Film (also referred to as "release film"); Protective film laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20 and / or the polarizing element 30 (also referred to as "surface protective film"). Examples thereof include an optically 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 polarizing element 30 via an adhesive layer or an adhesive layer. ..

[2] Polarizer The splitter 30 is a film having a function of selectively transmitting linearly polarized light in a certain direction from natural light. The splitter 30 includes, for example, an iodine-based polarizing element in which iodine as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, and a dichroic dye as a dichroic dye is adsorbed on a polyvinyl alcohol-based resin film. -Examples include an oriented dye-based polarizing element and a coating type polarizing element coated with a dichroic dye in a Riotrovic liquid crystal state and oriented / immobilized. These splitters are called absorption-type splitters because they selectively transmit linear polarization in one direction from natural light and absorb linear polarization in the other direction.

The polarizing element 30 is not limited to the absorption type polarizing element, but is a reflective polarizing element that selectively transmits linear polarization in one direction from natural light and reflects the linear polarization in the other direction, or linear polarization in the other direction. A scattering type polarizing element may be used, but an absorption type polarizing element is preferable from the viewpoint of excellent visibility when the polarizing plate is applied to an image display device or the like.
Above all, the polarizing element 30 is more preferably a polyvinyl alcohol-based polarizing element composed of a polyvinyl alcohol-based resin, and a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented on the polyvinyl alcohol-based resin film. It is more preferable that it is a polyvinyl alcohol-based polarizing element, and it is particularly preferable that it is a polyvinyl alcohol-based polarizing element in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film.
The polyvinyl alcohol-based polarizing element can be produced by a conventionally known method using a polyvinyl alcohol-based resin film (or layer).

The thickness of the splitter 30 can be 30 μm or less, 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 splitter 30 is usually 2 μm or more. Reducing the thickness of the polarizing element 30 is advantageous for reducing the thickness of the polarizing plate and, by extension, the image display device to which the polarizing plate 30 is applied.

[3] Thermoplastic Resin Film Each of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is a translucent (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin resin. (Polyethylene resin, polypropylene resin, etc.), cyclic polyolefin resin (norbornen resin, etc.) and other polyolefin resins; triacetyl cellulose, diacetyl cellulose and other cellulose ester resins; polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. Polyester-based resin; Polycarbonate-based resin; (meth) acrylic-based resin; or a film composed of a mixture thereof, a copolymer, or the like.

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be either an unstretched film or a uniaxially or biaxially stretched film, respectively. The biaxial stretching may be simultaneous biaxial stretching in which the two stretching directions are simultaneously stretched, or sequential biaxial stretching in which the stretching is performed in the first direction and then in a different second 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 polarizing element 30, or is a protective film that also has an optical function such as a retardation film. You can also do it.
For example, an arbitrary retardation value was given by stretching a film made of the thermoplastic resin (uniaxial stretching or biaxial stretching, etc.) or forming a liquid crystal layer or the like on the thermoplastic resin film. It can be a retardation film.

The (meth) acrylic resin can be, for example, a polymer containing a methacrylic acid ester as a main monomer (containing 50% by mass or more), and the methacrylic acid ester and other copolymerization components are copolymerized with each other. It is preferably a copolymer.
In one embodiment, the (meth) acrylic resin comprises methyl methacrylate as a copolymerization component, or comprises methyl methacrylate and methyl acrylate.

Examples of the copolymerization component other than methyl acrylate include ethyl methacrylate, n-, i- or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate and methacrylic acid. Methacrylic acid esters other than methyl methacrylate, such as 2-hydroxyethyl acid;
Acrylic acid esters such as ethyl acrylate, n-, i- or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate;
Methyl 2- (hydroxymethyl) acrylate, methyl 2- (1-hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, n-, i- or t-butyl 2- (hydroxymethyl) acrylate, etc. Hydroxyalkyl acrylates 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;
Unsaturatedimides such as phenylmaleimide and cyclohexylmaleimide;
Examples thereof include monofunctional monomers such as.
As the above-mentioned other monofunctional monomers, only one kind may be used alone, or two or more kinds may be used in combination.

A polyfunctional monomer may be used as the above-mentioned 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 (meth). Ethylene glycol such as acrylate, tetradecaethylene glycol di (meth) acrylate, or the hydroxyl groups at both ends of the oligomer are esterified with (meth) acrylic acid;
Esterification of both end hydroxyl groups of propylene glycol or its oligomers with (meth) acrylic acid;
A hydroxyl group of a dihydric alcohol such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) acrylate esterified with (meth) acrylic acid;
Bisphenol A, alkylene oxide adducts of bisphenol A, or both end hydroxyl groups of these halogen substituents esterified with (meth) acrylic acid;
Polyhydric alcohols such as trimethylolpropane and pentaerythritol esterified with (meth) acrylic acid, and glycidyl (meth) acrylate epoxy groups added to these terminal hydroxyl groups by ring opening;
Succinic acid, adipic acid, terephthalic acid, phthalic acid, dibasic acids such as these halogen substituents, or alkylene oxide adducts thereof to which an epoxy group of glycidyl (meth) acrylate is ring-opened and added;
Aryl (meth) acrylate; aromatic divinyl compounds such as divinylbenzene;
And so on.
Of these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

The (meth) acrylic resin may be modified by the reaction between the functional groups of the copolymer. The reaction includes, for example, a demethanol condensation reaction in a polymer chain of a methyl ester group of methyl (meth) acrylate and a hydroxyl group of methyl 2- (hydroxymethyl) acrylate, and a carboxyl group of (meth) acrylate. Examples thereof include a dehydration condensation reaction in a polymer chain with a hydroxyl group of methyl 2- (hydroxymethyl) acrylate.

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 the polymerization ratio of the methacrylic acid ester-based monomer and the acrylic acid ester-based monomer, the carbon chain length of each ester group, the types of functional groups having them, and the polyfunctional monomer for the entire monomer. It can be controlled by adjusting the polymerization ratio of the monomer.

It is also effective to introduce a ring structure into the main chain of the polymer as a means for increasing the glass transition temperature of the (meth) acrylic resin. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure and a lactone structure. Specific examples thereof include a cyclic acid anhydride structure such as a glutaric anhydride structure and a succinic anhydride structure; a cyclic imide structure such as a glutarimide structure and a succinic anhydride structure; and a lactone ring structure such as butyrolactone and valerolactone.
The larger the content of the ring structure in the main chain, the higher the glass transition temperature of the (meth) acrylic resin tends to be.
The cyclic acid anhydride structure and the cyclic imide structure are introduced by copolymerizing a monomer having a cyclic structure such as maleic anhydride and maleimide; a cyclic acid anhydride structure is obtained by a dehydration / demethanol condensation reaction after polymerization. Method of introduction; It can be introduced by a method of reacting an amino compound to introduce a cyclic imide structure or the like.
For a resin (polymer) having a lactone ring structure, after preparing a polymer having a hydroxyl group and an ester group in a polymer chain, the hydroxyl group and the ester group in the obtained polymer are required by heating. Therefore, it can be obtained by a method of forming a lactone ring structure by cyclization condensation in the presence of a catalyst such as an organic phosphorus compound.

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may contain additives, if necessary. Examples of the additive include a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, an impact resistance improving agent, a surfactant and the like.

The (meth) acrylic resin may contain acrylic rubber particles which are impact resistance improving agents from the viewpoint of film forming property on the film, impact resistance of the film, and the like. Acrylic rubber particles are particles containing an elastic polymer mainly composed of an acrylic acid ester as an essential component, and have a single-layer structure substantially composed of only this elastic polymer, or one elastic polymer. Examples thereof include a multi-layer structure having layers.
Examples of the elastic polymer include a crosslinked elastic copolymer containing an alkyl acrylate as a main component and copolymerized with another copolymerizable vinyl-based monomer and a crosslinkable monomer.
The alkyl acrylate which is the main component of the elastic polymer includes, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethyl hexyl acrylate, etc., which have an alkyl group having 1 or more and 8 or less carbon atoms. , And alkyl acrylate having an alkyl group having 4 or more carbon atoms is preferably used.
Examples of other vinyl-based monomers copolymerizable with the above alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methyl methacrylate. Methacrylic acid esters such as; aromatic vinyl compounds such as styrene; vinyl cyan compounds such as acrylonitrile and the like can be mentioned.
Examples of the crosslinkable monomer include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di (meth) acrylate and butane. Examples thereof include (meth) acrylates of polyhydric alcohols such as diol di (meth) acrylate; alkenyl esters of (meth) acrylic acid such as allyl (meth) acrylate; divinylbenzene and the like.

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 acrylic resin film is preferably laminated and bonded to the polarizing element 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 good adhesion particularly when the thermoplastic resin film is a (meth) acrylic resin film. Therefore, the adhesive composition according to the present invention can be suitably used for bonding a polarizing element and a (meth) acrylic resin film.
The (meth) acrylic resin film preferably has a resin component of the (meth) acrylic resin.

The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be films made of the same thermoplastic resin, or may be films made of different thermoplastic resins. The first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be the same or different in terms of thickness, presence / absence of additives, their types, retardation 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 resin film (preferably a cyclic polyolefin resin film) or a cellulose ester film. It is a resin or a polyester 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, and a charge on the outer surface thereof (the surface opposite to the polarizing element 30). A surface treatment layer (coating layer) such as an antifouling layer, an antifouling layer, and a conductive layer may be provided.

The thicknesses of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 are 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 or less, and further preferably 15 μm or more and 65 μm or less. Is. The thickness of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 may be 50 μm or less, or 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 the polarizing plate and the image display device to which the polarizing plate is applied.

From the viewpoint of improving adhesion, surface modification such as saponification treatment, plasma treatment, corona treatment, primer treatment, etc. is performed on the surface to which the adhesive composition of the first thermoplastic resin film 10 and the second thermoplastic resin film 20 is applied. Quality treatment may be performed.

[4] Manufacture of a polarizing plate and an adhesive layer By laminating and adhering a first thermoplastic resin film 10 to one surface of a polarizing element 30 via a first adhesive layer 15, the configuration shown in FIG. 1 is configured. A polarizing plate can be obtained, and the second thermoplastic resin film 20 is further laminated and adhered to the other surface of the polarizing element 30 via the second adhesive layer 25 to obtain a polarizing plate having the configuration shown in FIG. Obtainable.
When producing a polarizing plate having both a first thermoplastic resin film 10 and a second thermoplastic resin film 20 (hereinafter, these are collectively simply referred to as “thermoplastic resin film”), these thermoplastic resins are used. The film may be laminated and bonded one side at a time step by step, or the thermoplastic resin films on both sides may be laminated and bonded at the same time.

In the polarizing plate having the structure shown in FIG. 1, the first adhesive layer 15 is formed from the adhesive composition according to the present 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 from the adhesive composition according to the present invention. The first adhesive layer 15 and / or the second adhesive layer 25 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, one of the first adhesive layer 15 and the second adhesive layer 25 is formed from the adhesive composition according to the present invention, and the other is the adhesive composition according to the present invention. It may be formed from another adhesive composition different from the one.
Examples of other adhesive compositions include conventionally known water-based adhesives and active energy ray-curable adhesives.

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

The 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. When an active energy ray-curable adhesive is used, the adhesive layer of the polarizing plate is a cured product layer of the adhesive.

The active energy ray-curable adhesive can be an adhesive containing an epoxy-based compound that is cured by cationic polymerization as a curable component, and preferably an ultraviolet curable adhesive containing such an epoxy-based compound as a curable component. It is an agent. The epoxy-based compound means a compound having an average of one or more, preferably two or more epoxy groups in the molecule. Only one kind of epoxy compound may be used, or two or more kinds may be used in combination.

As the epoxy compound, a hydrided epoxy compound (having an alicyclic ring) obtained by reacting an alicyclic polyol obtained by reacting an aromatic ring of an aromatic polyol with epichlorohydrin Polyglycidyl ether of polyol); Aromatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof; epoxy compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule. Examples thereof include certain alicyclic epoxy compounds.

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

When the active energy ray-curable adhesive contains an epoxy-based compound that is cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; and iron-allene complexes.
When the active energy ray-curable adhesive contains a radically polymerizable component such as a (meth) acrylic compound, it preferably contains a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include an acetophenone-based initiator, a benzophenone-based initiator, a benzoin ether-based initiator, a thioxanthone-based initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like.

The adhesive composition is applied to the bonding surface of the polarizing element 30 and / or the bonding surface of the thermoplastic resin film, or the polarizing element 30 and the thermoplastic resin are bonded to each other. It is possible to include a step of injecting an adhesive composition between the film and the film, laminating both films via a layer of the adhesive composition, and pressing the films from above and below using, for example, a bonding roll or the like to bond the films. ..

For the formation of the adhesive composition layer, for example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Further, a method may be used in which the polarizing element 30 and the thermoplastic resin film are continuously supplied so that the bonding surface of both is on the inner side, and the adhesive composition is cast between them.

Before applying the adhesive composition, one or both of the bonded surfaces of the polarizing element 30 and the thermoplastic resin film are subjected to saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, and anchor coating treatment. You may perform easy-adhesion treatment (surface activation treatment) such as.

When an active energy ray-curable adhesive is used, the adhesive composition layer is cured by irradiating it with active energy rays.
The light source used for irradiating the active energy rays may be any light source capable of generating ultraviolet rays, electron beams, X-rays and the like. In particular, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave pumped mercury lamp, a metal halide lamp and the like having a emission distribution having a wavelength of 400 nm or less are preferably used.

The thickness of the adhesive layer formed from the adhesive composition according to the present invention is, for example, 0.1 μm or more and 100 μm or less, preferably 0.5 μm or more and 80 μm or less, and more preferably 1 μm or more and 60 μm in the polarizing plate. It is less than or equal to, and more preferably 2 μm or more and 50 μm or less. From the viewpoint of reducing the thickness of the polarizing plate, it is also preferable that the thickness of the adhesive layer is 30 μm or less, more preferably 20 μm or less.
The first adhesive layer 15 and the second adhesive layer 25 may have the same thickness or may be different in thickness.

[5] Other components of the polarizing plate [5-1] Optical functional film The polarizing plate can be provided with an optical functional film other than the polarizing element 30 for imparting a desired optical function. A suitable example thereof is a retardation film.
As described above, the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 can also serve as the retardation film, but the retardation film can also be laminated separately from the thermoplastic resin film. .. In the latter case, the retardation film can be laminated on the outer surface of the first thermoplastic resin film 10 and / or the second thermoplastic resin film 20 via the pressure-sensitive adhesive layer and the adhesive layer.

The retardation film is a birefringent film composed of a stretched film of a translucent thermoplastic resin; a film in which a discotic liquid crystal or a nematic liquid crystal is oriented and fixed; the above liquid crystal layer is formed on a base film. The ones that have been made 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 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 optically functional films (optical members) that may be included in the polarizing plate include a condenser plate, a brightness improving film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), and a light diffusing layer (light). Diffusing film) etc. These are generally provided when the polarizing plate is a polarizing plate arranged on the back surface side (backlight side) of the liquid crystal cell.

[5-2] Adhesive Layer The polarizing plate according to the present invention may include an adhesive layer for attaching the polarizing plate 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 the outer surface of the polarizing element 30 in the polarizing plate having the structure shown in FIG. 1, and the outer surface of the first thermoplastic resin film 10 or the second thermoplastic resin film 20 in the polarizing plate having the structure shown in FIG. Can be laminated to.

As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer, a (meth) acrylic resin, a silicone-based resin, a polyester-based resin, a polyurethane-based resin, a polyether-based resin, or the like as a base polymer can be used. Among them, a (meth) acrylic pressure-sensitive adhesive is preferable from the viewpoints of transparency, adhesive strength, reliability, weather resistance, heat resistance, reworkability and the like.

The thickness of the pressure-sensitive adhesive layer is determined according to the adhesive strength and the like, but a range of 1 μm or more and 50 μm or less is appropriate, and preferably 2 μm or more and 40 μm or less.

The polarizing plate may include a separate film laminated on the outer surface of the pressure-sensitive adhesive layer. The separate film can be a film made of a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate, or the like. Of these, a stretched film of polyethylene terephthalate is preferable.

The pressure-sensitive adhesive layer contains, if necessary, a filler made of glass fiber, glass beads, resin beads, metal powder or other inorganic powder, a pigment, a colorant, an antioxidant, an ultraviolet absorber, an antioxidant and the like. be able to.

[5-3] Protective film The polarizing plate according to the present invention may include a protective film for protecting the surface thereof (thermoplastic resin film surface, polarizing element surface, etc.). After the polarizing plate is attached to, for example, an image display element or another optical member, the protective film is peeled off and removed together with the pressure-sensitive adhesive layer contained therein.

The protective film is composed of, for example, a base film and an adhesive layer laminated on the base film. The above description is cited for the pressure-sensitive adhesive layer.
The resin constituting the base film is, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate resin. be able to. A polyester resin such as polyethylene terephthalate is preferable.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples,% and parts representing the content or the amount used are based on mass unless otherwise specified. The thickness of the film and the adhesive layer (cured film) was measured using a digital micrometer "MH-15M" manufactured by Nikon Corporation.

<Example 1>
(1) Preparation of Curable Adhesive Composition The components shown in Table 1 were mixed in the blending amounts shown in Table 1 to prepare a curable adhesive composition A. The unit of the blending amount of each component shown in Table 1 is a part by mass.

The details of each component shown in Table 1 are as follows.
(A): Maleic anhydride-modified liquid polybutadiene (trade name "Lithene ultra N4-5000-10MA" manufactured by Synthomer, number average molecular weight: 5500, viscosity at 25 ° C.: 25-60 Pa · sec, acid value: 54 KOHmg / g. )
(B-1a): Dicyclopentanyl acrylate (trade name "FA-513AS" manufactured by Hitachi Kasei Co., Ltd.)
(B-1b): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin Nakamura Chemical Industry Co., Ltd.)
(B-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin Nakamura Chemical Industry Co., Ltd., EO 10 mol)
(C): Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.).
(D): Unmodified liquid polybutadiene (trade name "Lithene ultra PM4" manufactured by Synthomer, number average molecular weight: 1500, viscosity at 25 ° C.: 0.7 to 0.95 Pa · sec)
(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 value): 610)

(2) Preparation of Polarizing Plate The surface of a polymethylmethacrylate (PMMA) film having a thickness of 60 μm is subjected to corona treatment, and the curable adhesive composition A prepared in (1) above is coated with an adhesive on the corona-treated surface. It was painted using the device. The obtained coating layer and a polyvinyl alcohol-iodine-based splitter having a thickness of 23 μm were laminated using a nip roll to obtain a splitter with a PMMA film.

Next, the surface of a retardation film [trade name "ZEONOR" manufactured by Nippon Zeon Corporation] having a thickness of 50 μm made of a cyclic polyolefin resin was subjected to corona treatment, and the corona-treated surface was subjected to a curable adhesive prepared according to the following. The composition B was coated using an adhesive coating device. The obtained coating layer and the polarizing element surface of the polarizing element with PMMA film were laminated using a nip roll to obtain a laminated body. From the retardation film side of this laminated body, the total integrated light amount (integrated amount of light irradiation intensity in the wavelength region of 320 to 400 nm) is about 200 mJ / cm ² (measuring instrument: measured value by UV Power Pack 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 with ultraviolet rays (UVB) to prepare a polarizing plate. The thickness of the cured layer of the curable adhesive composition A was about 10 μm, and the thickness of the cured layer of the curable adhesive composition B was 2.5 μm.

The curable adhesive composition B is 1,4- to 100 parts by mass of 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Ceroxide 2021P" manufactured by Daicel Co., Ltd.). 25 parts by mass of butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Corporation) and 5.6 parts by mass of photopolymerization initiator (trade name "CPI-100P" manufactured by Sun Appro Co., Ltd.) Was added and prepared by mixing.

<Examples 2 to 3, Comparative Example 1>
A curable adhesive composition A was prepared in the same manner as in Example 1 except that the blending amount of the blended components was changed as shown in Table 1. Further, a polarizing plate was produced in the same manner as in Example 1 except that the curable adhesive composition A was used.

<Measurement and evaluation>
(1) Moisture Permeability of a Cured Film Formed from a Curable Adhesive Composition A A curable adhesive composition A was applied to a 60 μm-thick PMMA film treated with a 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. Next, irradiate ultraviolet rays (UVB) having a total integrated light amount (integrated amount of light irradiation intensity in a wavelength region of 320 to 400 nm) of about 200 mJ / cm ² (measuring instrument: measured value by UV Power Pack II manufactured by Fusion UV). The adhesive layer was cured by the above method to obtain a laminate having a layer structure 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 structure 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 the measurement, the cured adhesive layer (cured film) of the above laminated body was set to be in an environment of a temperature of 40 ° C. and a relative humidity of 90%. In addition, the laminate was attached to the cup with the cured film facing outward.
The results are shown in the column of "Humidity permeability of laminated body" in Table 1. The numerical values in parentheses indicate the thickness (unit: μm) of the cured film of the laminated body.
Further, using the moisture permeability (Jt) of the obtained laminate, the moisture permeability (J) at a temperature of 40 ° C. and a relative humidity of 90% of the cured film itself was determined based on the following formula.
1 / Jt = (1 / J) + (1 / Jsub)
The PMMA film having a thickness of 60 μm, which is a base film, has a moisture permeability (Jsub) of 70 g / (m ² ·) measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% by the cup method specified in JIS Z 0208. It was 24hr).
The results are shown in the column of "Humidity permeability of cured film" in Table 1. The numerical values in parentheses indicate the thickness (unit: μm) of the cured film.

(2) Evaluation of adhesion between the polarizing element and the PMMA film in the polarizing plate (initial)
An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with a pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing element) and 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminated body. The obtained laminate was used as a test piece for measuring the peel strength between the polarizing element and the PMMA film. A cutter blade was inserted between the polarizing element of the test piece and the PMMA film, and the peeled portion was peeled off by 30 mm from the end in the length direction. For the test piece in this state, in an atmosphere with a temperature of 23 ° C. and a relative humidity of 55%, according to JIS K 6854-2: 1999 "Adhesive-Peeling Adhesive Strength Test Method-Part 2: 180 Degree Peeling". A peeling test was performed at a gripping movement speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripped portion was obtained, which was used as the peeling strength between the extruder and the PMMA film. The results are shown in Table 1. The peel strength was measured after the polarizing plate was prepared and then placed 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 high and the PMMA film or the polarizing element is broken before the film is peeled off. In Comparative Example 1, the adhesion between the polarizing element and the PMMA film was too weak to measure the peel strength.

(3) Evaluation of adhesion between the polarizing element and the PMMA film in the polarizing plate (after exposure to a high temperature and high humidity environment)
An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with a pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing element) and 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminated body. The obtained laminate was placed in a high temperature and high humidity environment with a temperature of 80 ° C. and a relative humidity of 90% RH for 24 hours, and then placed in an environment with a temperature of 23 ° C. and a relative humidity of 50% RH for 24 hours. After that, insert the blade of the cutter between the polarizing element of the obtained laminate and the PMMA film, peel it off by 30 mm from the end in the length direction, grasp the peeled part with the grip part of the testing machine, and the lower part of the grip is glass. I grabbed the board. For the test piece in this state, in an atmosphere with a temperature of 23 ° C. and a relative humidity of 55%, according to JIS K 6854-2: 1999 "Adhesive-Peeling Adhesive Strength Test Method-Part 2: 180 Degree Peeling". A peeling test was performed at a gripping movement speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripped portion was obtained, which was used as the peeling strength between the extruder and the PMMA film. The results are shown in Table 1.

<Example 4>
(1) Preparation of Curable Adhesive Composition The components shown in Table 2 were mixed in the blending amounts shown in Table 2 to prepare a curable adhesive composition C. The unit of the blending amount of each component shown in Table 2 is a mass part.

The details of each component shown in Table 2 are as follows.
(A): Maleic anhydride-modified liquid polybutadiene (trade name "Lithene ultra N4-5000-10MA" manufactured by Synthomer, number average molecular weight: 5500, viscosity at 25 ° C.: 25-60 Pa · sec, acid value: 54 KOHmg / g. )
(B-1a): Dicyclopentanyl acrylate (trade name "FA-513AS" manufactured by Hitachi Kasei Co., Ltd.)
(B-1b): Isostearyl acrylate (trade name "S-1800A" manufactured by Shin Nakamura Chemical Industry Co., Ltd.)
(B-1c): Lauryl acrylate (trade name "LA" manufactured by Osaka Organic Chemical Industry Co., Ltd.)
(B-1d): Butyl acrylate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.)
(B-2): Ethoxylated bisphenol A diacrylate (trade name "A-BPE-10" manufactured by Shin Nakamura Chemical Industry Co., Ltd., EO 10 mol)
(C): Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (trade name "Omnirad 819" manufactured by IGM Resins B.V.).
(D): Unmodified liquid polybutadiene (trade name "Lithene ultra PM4" manufactured by Synthomer, number average molecular weight: 1500, viscosity at 25 ° C.: 0.7 to 0.95 Pa · sec)
(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 value): 610)

(2) Preparation of Polarizing Plate The surface of a polymethylmethacrylate (PMMA) film having a thickness of 60 μm is subjected to corona treatment, and the curable adhesive composition C prepared in (1) above is coated with an adhesive on the corona-treated surface. It was painted using the device. The obtained coating layer and a polyvinyl alcohol-iodine-based splitter having a thickness of 23 μm were laminated using a nip roll to obtain a splitter with a PMMA film.

Next, the surface of a retardation film [trade name "ZEONOR" manufactured by Nippon Zeon Corporation] having a thickness of 50 μm made of a cyclic polyolefin resin was subjected to corona treatment, and the corona-treated surface was subjected to a curable adhesive prepared according to the following. The composition B was coated using an adhesive coating device. The obtained coating layer and the polarizing element surface of the polarizing element with PMMA film were laminated using a nip roll to obtain a laminated body. From the retardation film side of this laminated body, the total integrated light amount (integrated amount of light irradiation intensity in the wavelength region of 320 to 400 nm) is about 200 mJ / cm ² (measuring instrument: measured value by UV Power Pack 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 with ultraviolet rays (UVB) to prepare a polarizing plate. The thickness of the cured layer of the curable adhesive composition C was about 10 μm, and the thickness of the cured layer of the curable adhesive composition B was 2.5 μm.

The curable adhesive composition B is 1,4- to 100 parts by mass of 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Ceroxide 2021P" manufactured by Daicel Co., Ltd.). 25 parts by mass of butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Corporation) and 5.6 parts by mass of photopolymerization initiator (trade name "CPI-100P" manufactured by Sun Appro Co., Ltd.) Was added and prepared by mixing.

<Examples 5 to 8>
A curable adhesive composition C was prepared in the same manner as in Example 4 except that the blending amount of the blended components was changed as shown in Table 2. Further, a polarizing plate was produced in the same manner as in Example 4 except that the curable adhesive composition C was used.

<Measurement and evaluation>
(1) Moisture Permeability of a Cured Film Formed from a Curable Adhesive Composition C A curable adhesive composition C was applied to a 60 μm-thick PMMA film treated with a 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. Next, irradiate ultraviolet rays (UVB) having a total integrated light amount (integrated amount of light irradiation intensity in a wavelength region of 320 to 400 nm) of about 200 mJ / cm ² (measuring instrument: measured value by UV Power Pack II manufactured by Fusion UV). The adhesive layer was cured by the above method to obtain a laminate having a layer structure 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 structure 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 the measurement, the cured adhesive layer (cured film) of the above laminated body was set to be in an environment of a temperature of 40 ° C. and a relative humidity of 90%. In addition, the laminate was attached to the cup with the cured film facing outward.
The results are shown in the column of "Humidity permeability of laminated body" in Table 2. The numerical values in parentheses indicate the thickness (unit: μm) of the cured film of the laminated body.
Further, using the moisture permeability (Jt) of the obtained laminate, the moisture permeability (J) at a temperature of 40 ° C. and a relative humidity of 90% of the cured film itself was determined based on the following formula.
1 / Jt = (1 / J) + (1 / Jsub)
The PMMA film having a thickness of 60 μm, which is a base film, has a moisture permeability (Jsub) of 70 g / (m ² ·) measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% by the cup method specified in JIS Z 0208. It was 24hr).
The results are shown in the column of "Humidity permeability of cured film" in Table 2. The numerical values in parentheses indicate the thickness (unit: μm) of the cured film.

(2) Evaluation of adhesion between the polarizing element and the PMMA film in the polarizing plate (initial)
An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with a pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing element) and 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminated body. The obtained laminate was used as a test piece for measuring the peel strength between the polarizing element and the PMMA film. A cutter blade was inserted between the polarizing element of the test piece and the PMMA film, and the peeled portion was peeled off by 30 mm from the end in the length direction. For the test piece in this state, in an atmosphere with a temperature of 23 ° C. and a relative humidity of 55%, according to JIS K 6854-2: 1999 "Adhesive-Peeling Adhesive Strength Test Method-Part 2: 180 Degree Peeling". A peeling test was performed at a gripping movement speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripped portion was obtained, which was used as the peeling strength between the extruder and the PMMA film. The results are shown in Table 2. The peel strength was measured after the polarizing plate was prepared and then placed 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 high and the PMMA film or the polarizing element is broken before the film is peeled off.

(3) Evaluation of adhesion between the polarizing element and the PMMA film in the polarizing plate (after exposure to a high temperature and high humidity environment)
An adhesive layer was formed on the PMMA film side of the obtained polarizing plate. The obtained polarizing plate with a pressure-sensitive adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizing element) and 25 mm in width, and the pressure-sensitive adhesive layer was bonded to a glass plate to obtain a laminated body. The obtained laminate was placed in a high temperature and high humidity environment with a temperature of 80 ° C. and a relative humidity of 90% RH for 24 hours, and then placed in an environment with a temperature of 23 ° C. and a relative humidity of 50% RH for 24 hours. After that, insert the blade of the cutter between the polarizing element of the obtained laminate and the PMMA film, peel it off by 30 mm from the end in the length direction, grasp the peeled part with the grip part of the testing machine, and the lower part of the grip is glass. I grabbed the board. For the test piece in this state, in an atmosphere with a temperature of 23 ° C. and a relative humidity of 55%, according to JIS K 6854-2: 1999 "Adhesive-Peeling Adhesive Strength Test Method-Part 2: 180 Degree Peeling". A peeling test was performed at a gripping movement speed of 300 mm / min, and an average peeling force over a length of 170 mm excluding 30 mm of the gripped portion was obtained, which was used as the peeling strength between the extruder 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 extruder.

Claims (10)

It contains a maleic anhydride-modified compound (A), a (meth) acrylate compound (B) and a photopolymerization initiator (C).
The (meth) acrylate compound (B) contains a monofunctional (meth) acrylate compound (B-1).
The monofunctional (meth) acrylate compound (B-1) is a curable adhesive composition containing an alicyclic alkyl (meth) acrylate compound and a linear or branched _C4 -C ₃₆ alkyl (meth) acrylate compound. .. The curability according to claim 1, wherein the content of the monofunctional (meth) acrylate compound (B-1) is 60% by mass or more and 99% by mass or less in 100% by mass of the (meth) acrylate compound (B). Adhesive composition. The content of the alicyclic alkyl (meth) acrylate compound is 100% by mass, which is the total amount of the alicyclic alkyl (meth) acrylate compound and the linear or branched _C4 -C ₃₆ alkyl (meth) acrylate compound. The curable adhesive composition according to claim 1 or 2, wherein the content is 5% by mass or more and 80% by mass or less. The curable adhesive composition according to any one of claims 1 to 3, further comprising unmodified polybutadiene (D). The claim that the content of the maleic anhydride-modified compound (A) is 40% by mass or more and 90% by mass or less in the total amount of 100% by mass of the maleic anhydride-modified compound (A) and the unmodified polybutadiene (B). 4. The curable adhesive composition according to 4. The curable adhesive composition according to any one of claims 1 to 5, further comprising the petroleum resin (E). The curable adhesive composition according to any one of claims 1 to 6, wherein the maleic anhydride-modified compound (A) contains a maleic anhydride-modified polymer (A-1). The cured film having a thickness of 10 μm made of the curable adhesive composition has a moisture permeability of 400 g / ( ^m 2.24 hr) or less at a temperature of 40 ° C. and a relative humidity of 90%, according to any one of claims 1 to 7. The curable adhesive composition according to description. A polarizing plate containing a polarizing element, an adhesive layer, and a thermoplastic resin film in this order.
The adhesive layer is a polarizing plate which is a cured product layer of the curable adhesive composition according to any one of claims 1 to 8. The polarizing plate according to claim 9, wherein the thermoplastic resin film is a (meth) acrylic resin film.

Images