TWI688626B - Adhesive composition for polarizing plate, adhesive sheet, polarizing plate with adhesive layer and laminate - Google Patents

Abstract

This invention provides an adhesive composition for polarizing plate, which has excellent anti-static property and is capable of forming an adhesive layer with durability under high-temperature and high-moisture environment.

This invention provides an adhesive composition for polarizing plate containing (A) a (meth)acrylic polymer obtained by polymerizing a polymerizable monomer having 41 mass% or more of a (meth) acrylate easter (a1) having a polyoxyalkylene group or an alkoxy alkyl group, (B) crosslinker, (C) an ionic compound in which an anion is selected from N,N-bis(fluorosulfonyl)imide and N,N-bis(trifluoromethanesulfonyl)imide, a cation is organic cation and has a melting point of 25℃ or more.

Description

Adhesive composition for polarizing plate, adhesive sheet, polarizing plate and layered body with adhesive layer

The invention relates to an adhesive composition for polarizing plates, an adhesive sheet, a polarizing plate with an adhesive layer and a laminate.

In recent years, the use of liquid crystal elements in vehicle mounting, outdoor tools, computer monitors, televisions, etc. has gradually expanded, and consequently the use environment has become very severe. The liquid crystal element has a structure in which a liquid crystal material is sandwiched between two substrates (e.g., a glass plate), and a polarizing plate is adhered to the surface of the substrate through an adhesive layer. However, the aforementioned adhesive layer also requires durability under high temperature/high humidity.

When the adhesive layer for polarizing plates is used in the manufacture of liquid crystal devices, it is usually attached to the polarizing plate in a state where a cover film with a peeling treatment is attached to one side, and then, the cover film is peeled off to make the adhesive layer After exposure, it is attached to the substrate. At this time, static electricity is generated due to the high insulating properties of the cover film and the polarizing plate, which further causes adverse effects such as chaotic alignment of the liquid crystal and damage to electronic parts.

Therefore, antistatic properties are also required for the adhesive layer for polarizing plates. As an adhesive layer for polarizing plates with antistatic properties, there has been reported a technique for containing an ionic compound in the adhesive composition forming the adhesive layer.

For example, Patent Document 1 describes an adhesive composition containing: an acrylic resin obtained by polymerizing a specific (meth)acrylate, an ionic compound having an organic cation and being solid at room temperature, and Crosslinking agent. Patent Literature 2 describes an adhesive composition containing an ionic compound having a melting point of 50° C. or higher and a base polymer having a glass transition temperature of 0° C. or lower.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1]: Japanese Patent Laid-Open No. 2010-66756

[Patent Document 2]: Japanese Patent Laid-Open No. 2009-19162

Generally speaking, the polarizing plate mostly has a protective film for protecting the polarizer. The adhesive layer is formed by bonding the protective film. However, after reviewing by the present inventors, it is understood that under humid and hot environments, the ionic compounds contained in the adhesive layer will cause hydrolysis of the polymer components of the protective film, corrosion of the polarizing plate, etc. cause problems. In addition, due to the widening of the thickness of other components and the scope of use, it is required that even under more severe conditions than the long-term tests so far, The aforementioned problem arises.

An object of the present invention is to provide an adhesive composition for polarizing plates that has excellent antistatic performance and can form an adhesive layer that is durable under high temperature and high humidity, and an adhesive sheet having an adhesive layer formed by the foregoing composition , A polarizing plate with an adhesive layer with the adhesive layer, and a laminate with the adhesive layer.

In order to solve the above-mentioned problems, the present inventor has conducted a intensive review. As a result, it was found that when a (meth)acrylic polymer obtained from a polymerizable monomer containing a specific amount of a specific (meth)acrylate, a crosslinking agent, and a specific ionic compound are used in combination, it can be solved The above subject further completes the present invention.

The present invention is, for example, the following [1] to [6].

[1] An adhesive composition for polarizing plates, comprising: (A) polymerizing (meth)acrylate (a1) containing 41 mass% or more of polyoxyalkylene or alkoxyalkyl group (Meth)acrylic polymer obtained by polymerizing a reactive monomer; (B) crosslinking agent; (C) anion is selected from N,N-bis(fluorosulfonyl)imide and N,N-bis (Trifluoromethanesulfonyl) amide imide, an ionic compound with an organic cation and a melting point of 25°C or higher.

[2] An adhesive composition for polarizing plates as described in [1], which further includes a silane coupling agent (D).

[3] The adhesive composition for polarizing plates according to [1] or [2], wherein, in the ionic compound (C), the organic cation is a tetraalkylammonium represented by the formula (c-1) cation.

[式(c-1)中，R¹、R²、R³及R⁴各自獨立為烷基。]

[In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group. ]

[4] An adhesive sheet for polarizing plates having an adhesive layer formed by the polarizing plate adhesive composition according to any one of [1] to [3].

[5] A polarizing plate with an adhesive layer, comprising a polarizing plate and at least one side of the polarizing plate, by the polarizing plate adhesive according to any one of [1] to [3] The adhesive layer formed by the composition.

[6] A laminate, which is a laminate of polarizers and protective films in sequence, an adhesive layer formed by the adhesive for the polarizing plate described in any one of claims 1 to 3, and a glass substrate ; Wherein the polarizing plate has a polarizer and a protective film disposed on the polarizer.

According to the present invention, it is possible to provide a polarizing plate having an excellent antistatic performance and capable of forming an adhesive layer having durability under high temperature and high humidity An adhesive composition, an adhesive sheet having an adhesive layer formed by the foregoing composition, a polarizing plate with an adhesive layer attached to the adhesive layer, and a laminate having the adhesive layer.

Hereinafter, the adhesive composition for polarizing plates of the present invention, the adhesive sheet for polarizing plates, the polarizing plate with an adhesive layer and the laminate will be described. In the following, the adhesive composition for polarizing plates of the present invention is also simply referred to as "adhesive composition", and the adhesive sheet for polarizing plates of the present invention is also simply referred to as "adhesive sheet".

In this specification, acrylic acid and methacrylic acid are collectively referred to and described as "(meth)acrylic acid".

[Adhesive composition for polarizing plate]

The adhesive composition for polarizing plates of the present invention is described below, and contains (meth)acrylic polymer (A), crosslinking agent (B), and ionic compound. The aforementioned adhesive composition may contain a silane coupling agent (D) as needed, and may also contain an organic solvent (E).

[(Meth)acrylic polymer (A)]

The (meth)acrylic polymer (A) is a polymer containing a polymerizable monomer having a (meth)acrylate (a1) having a polyoxyalkylene group or an alkoxyalkyl group, and the polymerizable monomer It is obtained by body polymerization. Therefore, (meth)acrylic polymer The compound (A) preferably has a structural unit derived from (a1).

The polymerizable monomer is not only a (meth)acrylate (a1) having a polyoxyalkylene group or an alkoxyalkyl group, but may also be selected from the group (a1) and further containing At least one of the (meth)acrylate (a2), the monomer (a3) containing a crosslinkable group, and the other monomer (a4) of any of the group, the alkoxyalkyl group, and the crosslinkable group One kind. For example, the polymerizable monomer containing the above-mentioned (a1) to (a3) and (a4) as necessary is cited.

Here, the aforementioned crosslinkable group is a group capable of introducing a crosslinkable point along with the crosslinkable agent of the crosslinking agent (B) into the (meth)acrylic polymer (A), and examples thereof include a hydroxyl group and a carboxyl group. .

Hereinafter, the (meth)acrylate (a1) is called "monomer (a1)", and the (meth)acrylate (a2) is called "monomer (a2)" and contains a crosslinkable group The monomer (a3) is called "monomer (a3)", and the other monomer (a4) is called "monomer (a4)".

"Single (a1)"

The monomer (a1) is a (meth)acrylate having a polyoxyalkylene or alkoxyalkyl group. The monomer (a1) is preferably a (meth)acrylate having no crosslinkable group.

The monomer (a1) is represented by the formula (a-1), for example.

CH ₂ =CR ¹ -COOR ² …(a-1)

R ¹ is a hydrogen atom or a methyl group, and R ² is a group represented by formula (g-1).

-(R ³ O) _n R ⁴ …(g-1)

R ³ is an alkylene group, R ⁴ is an alkyl group, and n is an integer of 1 or more. The carbon number of the alkylene group is usually 1 to 10, preferably 1 to 5. The carbon number of the alkyl group is usually 1 to 10, preferably 1 to 4. n is preferably 1 to 20, more preferably 1 to 4, and still more preferably 1 to 2.

Examples of the monomer (a1) include alkoxyalkyl (meth)acrylates and alkoxyalkyl polyalkylene glycol mono(meth)acrylates.

Examples of alkoxyalkyl (meth)acrylates include: methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, (meth)acrylic acid- 2-ethoxyethyl ester, (meth)acrylic acid-3-methoxypropyl ester, (meth)acrylic acid-3-ethoxypropyl ester, (meth)acrylic acid-4-methoxy Butyl ester, 4-ethoxybutyl (meth)acrylate.

Examples of alkoxyalkyl polyalkylene glycol mono(meth)acrylates include methoxydiethylene glycol mono(meth)acrylate and methoxydipropylene glycol mono(meth)acrylic acid. Ester, ethoxytriethylene glycol mono(meth)acrylate, ethoxydiethylene glycol mono(meth)acrylate, methoxytriethylene glycol mono(meth)acrylate.

As the monomer (a1), among these, from the viewpoint of reactivity, it is preferable that R ² of the formula (a-1) is an alkoxyalkyl (meth)acrylate which is an alkoxyalkyl group.

As the monomer (a1) system, one kind may be used alone, or two or more kinds may be used in combination.

Of 100% by mass of the polymerizable monomer forming the (meth)acrylic polymer (A), the amount of the monomer (a1) used is 41% by mass or more, preferably 50% by mass or more, and more preferably 60 to 99.3 quality%.

If the usage amount of the monomer (a1) is 41% by mass or more, the adhesive formed by the adhesive composition containing the (meth)acrylic polymer (A) The agent layer exhibits high polarity and has excellent adhesion to polarizing plates and substrates (especially glass plates) and the like. Therefore, even under high temperature and high humidity, floating or peeling of the adhesive layer from the polarizing plate or the substrate does not occur, and the adhesive layer can be excellent in durability. In addition, since the adhesiveness to the base material is excellent, the reworkability is good, and further, it is difficult to cause adhesion of the adhesive layer to the punching blade, the peripheral polarizing plate, etc., so the workability is excellent. When the usage amount of the monomer (a1) is 50% by mass or more, the aforementioned effect is more remarkable. If the usage amount of the monomer (a1) is within the aforementioned range, the (meth)acrylic polymer (A) has a good affinity with the ionic compound (C) described later, and the bleed of the ionic compound (C) can also be suppressed .

"Single (a2)"

The monomer (a2) is (meth)acrylate which does not have any of polyoxyalkylene group, alkoxyalkyl group and crosslinkable group. The (meth)acrylic polymer (A) preferably has the structural unit derived from (a2).

The monomer (a2) is represented by the formula (a-2), for example.

CH ₂ =CR ⁵ -COOR ⁶ …(a-2)

R ⁵ is a hydrogen atom or a methyl group, and R ⁶ is an organic group that does not have any of a polyoxyalkylene group, an alkoxyalkyl group, and a crosslinkable group.

Examples of the organic group in R ⁶ include alicyclic groups such as alkyl groups and cycloalkyl groups; aryl groups, aralkyl groups, aryloxyalkyl groups, and amine alkyl groups substituted with N-monoalkyl groups. The carbon number of the alkyl group is usually 1 to 24. The carbon number of alicyclic groups such as cycloalkyl groups is usually 3 to 15. The carbon number of the aryl group is usually 6 to 10. The aralkyl group is generally composed of an alkylene group having 1 to 6 carbon atoms and an aryl group having 6 to 10 carbon atoms. The carbon number of amine alkyl substituted with N-monoalkyl is usually 1 to 12.

Examples of the monomer (a2) include alicyclic base-containing (meth)acrylates such as alkyl (meth)acrylate and cycloalkyl (meth)acrylate; and aryl (meth)acrylate Aralkyl (meth)acrylate; oxyalkyl (meth)acrylate; (meth)acrylate containing amine alkyl substituted with N-monoalkyl.

Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, (meth) ) N-butyl acrylate, isobutyl (meth) acrylate, third butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate , 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, N-decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate , (Octadecyl methacrylate).

Examples of (meth)acrylates containing alicyclic groups such as cycloalkyl (meth)acrylates, aryl (meth)acrylates, and aralkyl (meth)acrylates include, for example: (methyl) Cyclohexyl acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate.

Examples of aryloxyalkyl (meth)acrylates include phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and (meth)acrylic acid-2- Tolyloxymethyl, xyloxymethyl (meth)acrylate, naphthylmethyl (meth)acrylate.

Examples of (meth)acrylates containing amine alkyl substituted with N-monoalkyl include monomethylaminoethyl (meth)acrylate and monoethylaminoethyl (meth)acrylate Ester, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate.

As the monomer (a2) system, one kind may be used alone, or two or more kinds may be used in combination.

Of 100% by mass of the polymerizable monomer forming the (meth)acrylic polymer (A), the amount of the monomer (a2) used is preferably less than 59% by mass, more preferably 0.2 to 49.9% by mass, and still more It is 0.5 to 39.8% by mass.

"Single (a3)"

The monomer (a3) is a monomer containing a crosslinkable group. The (meth)acrylic polymer (A) may have a structural unit derived from (a3).

As the polymerizable monomer constituting the (meth)acrylic polymer (A), when the monomer (a3) is used, a crosslinkable point that can be crosslinked with the crosslinking agent can be introduced into the (meth)acrylic system Polymer (A).

The monomer (a3) is represented by the formula (a-3), for example.

CH ₂ =CR ⁷ -COOR ⁸ …(a-3)

R ⁷ is a hydrogen atom or a methyl group, and R ⁸ is an organic group having a crosslinkable group. Examples of the crosslinkable group include a hydroxyl group and a carboxyl group.

Examples of the organic group in R ⁸ include a hydroxyalkyl group having 1 to 12 carbon atoms, an aliphatic group substituted with a carboxyl group, and the like.

Examples of the monomer (a3) include (meth)acrylates containing hydroxyl groups and (meth)acrylates containing carboxyl groups.

Examples of (meth)acrylates containing hydroxyl groups include (meth)acrylic acid hydroxyl groups Alkyl esters, etc., for example: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (meth)acrylic acid- 6-hydroxyhexyl ester, 8-hydroxyoctyl (meth)acrylate.

Examples of carboxyl group-containing (meth)acrylates include (meth)acrylic acid-β-carboxyethyl ester and (meth)acrylic acid-5-carboxypentyl ester.

As the monomer (a3), in addition to the compound represented by the formula (a-3), an ethylenically unsaturated carboxylic acid may also be mentioned. Examples of ethylenically unsaturated carboxylic acids include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid.

As the monomer (a3) system, one kind may be used alone, or two or more kinds may be used in combination.

The use amount of the monomer (a3) in 100% by mass of the polymerizable monomer forming the (meth)acrylic polymer (A) is from the viewpoint of durability by moderate crosslinking and expression of stress relaxation characteristics It is preferably more than 0% by mass and 15% by mass or less, more preferably 0.1 to 10% by mass, and still more preferably 0.2 to 5% by mass.

"Single (a4)"

The (meth)acrylic polymer (A) may contain structural units derived from the monomer (a4).

Examples of the monomer (a4) include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene and α-methyl Styrene-based monomers such as styrene; diene-based monomers such as butadiene, isoprene, chloroprene; nitrile-based monomers such as (meth)acrylonitrile; monomers containing an amide group.

Examples of monomers containing an amide group include (meth)acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acrylamide, etc. Monoalkyl-substituted acrylic amide; N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, and other N,N-dialkyl-substituted acrylic amide.

As the monomer (a4) system, one kind may be used alone, or two or more kinds may be used in combination.

"Production conditions of (meth)acrylic polymer (A)"

The (meth)acrylic polymer (A) system can be produced by a conventionally known polymerization method such as solution polymerization method, bulk polymerization method, emulsification polymerization method, suspension polymerization method, etc. Solution polymerization method. Specifically, a polymerization solvent and a polymerizable monomer are placed in the reaction vessel, and a polymerization initiator is added under an inert gas environment such as nitrogen gas. The reaction initiation temperature is usually 40 to 100°C, preferably 50 to At 80°C, the reaction system is usually maintained at a temperature of 50 to 90°C, preferably 60 to 90°C, and allowed to react for 4 to 20 hours.

Examples of the polymerization initiator include azo-based initiators and peroxide-based polymerization initiators.

As the azo-based initiator, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2 ,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methyl Butyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy -2,4-Dimethylvaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethylene isobutane Amidam), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl Group)-propionylamide], 2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanovaleric acid), 2,2'- Azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-propionic acid methyl ester), 2,2'-azobis[2-methyl-N- (2-hydroxyethyl)] azo compounds such as amide propionate.

Examples of the peroxide-based initial polymerization agent include tertiary butyl peroxide, cumene hydroperoxide, cumylhydroperoxide, cumylhydroperoxide, benzoyl peroxide, lauryl peroxide, Peroxyhexylanyl peroxide, diisopropyl peroxycarbonate, di-2-ethylhexyl peroxycarbonate, tertiary butyl peroxypivalate, 2,2'-bis(4,4'- Di 3rd butyl cyclohexyl peroxide) propane, 2,2'-bis(4,4'-di-third pentylcyclohexyl peroxide) propane, 2,2'-bis(4,4'-di Trioctylcyclohexyl peroxide) propane, 2,2'-bis(4,4'-di-α-cumylcyclohexyl peroxide) propane, 2,2'-bis(4,4'-di third Butyl cyclohexyl peroxide) butane, 2,2'-bis (4,4'-di-third octyl cyclohexyl peroxide) butane.

As the polymerization initiator system, one kind may be used alone, or two or more kinds may be used in combination.

There is no limit to the addition of multiple polymerization initiators during the polymerization.

The polymerization initiator is generally used in an amount in the range of 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass relative to 100 parts by mass of the polymerizable monomer forming the (meth)acrylic polymer (A). In addition, a polymerization initiator, a chain transfer agent, a polymerizable monomer, and a polymerization solvent may be appropriately added during the polymerization reaction.

烷、苯甲醚、苯乙醚、二苯基醚等醚類；氯仿、四氯化碳、1,2-二氯乙烷、氯苯等鹵化烴類；乙酸乙酯、乙酸丙酯、乙酸丁酯、乙酸乙酯、丙酸甲酯等酯類；丙酮、甲基乙基酮、二乙基酮、甲基異丁基酮、環己酮等酮類；N,N-二甲基甲醯胺、N,N-二甲基乙醯胺、N-甲基吡咯烷酮等醯胺類；乙腈、芐腈等腈類；二甲基亞碸、環丁碸等碸類等。 Examples of the polymerization solution used in the solution polymerization include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; and cyclopentane and cyclohexane Alkane, cycloheptane, cyclooctane and other alicyclic hydrocarbons; diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, di

Alkanes, anisole, phenethyl ether, diphenyl ether and other ethers; chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene and other halogenated hydrocarbons; ethyl acetate, propyl acetate, butyl acetate Ester, ethyl acetate, methyl propionate and other esters; acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; N,N-dimethyl formamide Amides such as amines, N,N-dimethylacetamide and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; dimethyl sulfoxides, ciprones, etc.

One type of polymerization solution may be used alone, or two or more types may be used in combination.

"Physical properties and content of (meth)acrylic polymer (A)"

(Meth)acrylic polymer (A), for example, the weight-average molecular weight (Mw) measured by gel permeation chromatography (GPC method), in polystyrene conversion value, is usually 400,000 or more , Preferably 450,000 to 2 million, more preferably 600,000 to 1.8 million, and still more preferably 800,000 to 1.8 million polymer (A-1). When Mw is equal to or greater than the aforementioned lower limit, it is preferable from the viewpoint of the durability of the adhesive layer. When Mw is equal to or lower than the above upper limit, it is preferable from the viewpoint of the coatability of the adhesive composition.

The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the polymer (A-1) measured by the GPC method is usually 2 to 60, preferably 3 to 45, and more preferably 3 to 20. When Mw/Mn is equal to or greater than the aforementioned lower limit, the viewpoint of exhibiting adhesion to the substrate or polarizing plate is preferred. When Mw/Mn is below the above upper limit, the durability from excellent heat resistance is maintained Is better.

The (meth)acrylic polymer (A) series may be composed only of the above-mentioned polymer (A-1). In addition, the (meth)acrylic polymer (A) may be a mixture of the polymer (A-1) and the low molecular weight polymer (A-2). When using the aforementioned mixture, it is preferable from the viewpoint of improvement of wettability and improvement of stress mixability.

The content of the low molecular weight polymer (A-2) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 1 with respect to 100 parts by mass of the polymer (A-1). To 30 parts by mass.

The Mw of the low-molecular-weight polymer (A-2) measured by the GPC method in terms of polystyrene is usually 50,000 or less, preferably 1,000 to 50,000, and more preferably 2,000 to 20,000.

The glass transition temperature (Tg) of the (meth)acrylic polymer (A) can be measured by a differential scanning calorimeter, and the monomer units and the content ratio of the copolymer can be determined by Calculate by Fox's formula. For example, when the glass transition temperature (Tg) obtained by the Fox formula is usually -70 to 10°C, preferably -60 to 0°C, the (meth)acrylic polymer (A) can be synthesized. The glass transition temperature of the homopolymer containing each monomer in the Fox formula can be, for example, the value described in the Polymer Handbook Forth Edition (Wiley-Interscience 2003).

[Crosslinking agent (B)]

The adhesive composition of the present invention contains a crosslinking agent (B). Crosslinking agent B series It is appropriately selected according to the crosslinkable group that can be introduced into the (meth)acrylic polymer (A). For example, an isocyanate compound, an epoxy compound, and a metal chelate compound can be used.

By crosslinking the (meth)acrylic polymer (A) with a crosslinking agent (B), a crosslinked body (Network polymer) can be formed, and an adhesive layer with excellent heat resistance can be obtained.

As the crosslinking agent (B), one type may be used alone, or two or more types may be used in combination.

In the adhesive composition of the present invention, the content of the crosslinking agent (B) is appropriately selected according to the (meth)acrylic polymer (A), and the content of the (meth)acrylic polymer (A) ) For 100 parts by mass, preferably 0.01 to 25 parts by mass. More preferably, the content of the crosslinking agent (B) is 0.01 to 3 parts by mass when the Mw of the (meth)acrylic polymer (A-1) is 800,000 or more; 400,000 and less than 800,000 , 5 to 25 parts by mass.

When the Mw of (A-1) is 800,000 or more, by preparing the crosslinking agent (B) within the above range, the adhesive layer system formed of the adhesive composition can exhibit stress relaxation characteristics and obtain sufficient heat resistance. In addition, it exhibits excellent flexibility and adhesion. (A-1) When the Mw is more than 400,000 and less than 800,000, by mixing the crosslinking agent (B) within the above range, the adhesive layer formed from the adhesive composition, by the aggregation of the adhesive layer Sufficient heat resistance. In addition, the adhesion to the substrate of the adhesive layer, the protrusion from the base material, the punching blade, and the peripheral polarizing plate is suppressed, and excellent workability is exhibited.

As the isocyanate compound, an isocyanate compound having 2 or more isocyanate groups in one molecule is generally used, preferably 2 to 8, More preferably, it is 3 to 6. When the number of isocyanate groups is in the aforementioned range, it is preferred from the viewpoint of the efficiency of the crosslinking reaction between the (meth)acrylic polymer (A) and the isocyanate compound, and the viewpoint of maintaining the flexibility of the adhesive layer.

Examples of the isocyanate compound having 2 or more isocyanate groups in one molecule include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate. Examples of the aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, and 3-methyl The aliphatic diisocyanates having 4 to 30 carbon atoms, such as alkyl-1,5-pentane diisocyanate and 2,2,4-trimethyl-1,6-hexane diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated dimethylbenzene diisocyanate, hydrogenated tolyl diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethyl dimethyl Cycloaliphatic diisocyanate having 7 to 30 carbon atoms such as benzene diisocyanate. Examples of the aromatic diisocyanate include benzene diisocyanate, methyl diisocyanate, dimethyl diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate. Aromatic diisocyanates with 8 to 30 carbon atoms.

Examples of the isocyanate compound having 3 or more isocyanate groups in one molecule include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate. Specific examples include 2,4,6-triisocyanate methylbenzene, 1,3,5-triisocyanate benzene, and 4,4,4′-triphenylmethane triisocyanate.

Also, examples of the isocyanate compound include isocyanate Among the above isocyanates with 2 or 3 or more acid esters, polymers (for example: 2 or 3 polymers, biuret, isocyanurate), derivatives (for example: polyol and 2 molecules Addition reaction product of the above diisocyanate compound), polymer. As the polyols in the aforementioned derivatives, low molecular weight polyols include, for example, trivalent or higher alcohols such as trimethylolpropane, glycerin, and neopentyl alcohol; polymer polyols include, for example, polyether polyols and polyester polyols Alcohol, acrylic polyol, polybutadiene polyol, polyisoprene polyol.

Examples of such isocyanate compounds include terpolymers of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate or tolyl diisocyanate biuret or isocyanurate. Acid ester, reaction product of trimethylolpropane and tolyl diisocyanate or xylyl diisocyanate (for example: 3-molecular adduct of tolyl diisocyanate or xylyl diisocyanate), trimethylol propane The reaction product with hexamethylene diisocyanate (for example: 3 molecular adducts of hexamethylene diisocyanate).

Among the isocyanate compounds, from the viewpoint of improving the curing property and light leakage resistance, the reaction product of trimethylolpropane and tolyl diisocyanate or xylyl diisocyanate (CORONATE manufactured by Nippon Polyurethane Industry Co., Ltd.) is preferred L, TD-75, etc., manufactured by Soken Chemical Co., Ltd.), cyanurate of hexamethylene diisocyanate or tolyl diisocyanate (TSE-100 manufactured by Asahi Kasei Industries Co., Ltd., Japan Polyurethane Industry Co., Ltd. 2050, etc.).

Examples of epoxy compounds are compounds having two or more epoxy groups in the molecule, and examples include ethylene glycol epoxypropyl ether and polyethylene. Glycol glycidyl ether, glycerol glycidyl ether, glycerol triglycidyl propyl ether, 1,6-hexanediol glycidyl propyl ether, trimethylol propane glycidyl ether , Epoxypropylaniline, Diaminoglycidoxypropylamine, N,N,N',N'-tetraepoxypropyl m-xylylenediamine, 1,3-bis(N,N'-diamine Base epoxypropyl amine methyl). As a commercially available product, for example, E-5CM manufactured by Chongken Chemical Co., Ltd. and E-5XM manufactured by Chongken Chemical Co., Ltd.

Examples of the metal chelate compound include, on polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium, alkoxides, acetone, and acetyl Compounds such as ethyl acetate for coordination. Specifically, aluminum isopropoxide, secondary aluminum butyrate, ethyl acetate/diisopropyl aluminum, ethyl acetate aluminum, and aluminum pyruvate are listed.

[Ionic compound (C)]

The adhesive composition of the present invention contains an anion selected from bis(fluorosulfonyl)amide imine and N,N-bis(trifluoromethanesulfonyl)amide imide and an organic cation and has a melting point of 25°C The above ionic compound (C).

Since the adhesive composition contains the ionic compound (C), the surface resistance value of the adhesive layer formed of the adhesive composition can be reduced, and an adhesive layer having antistatic properties can be obtained.

In addition, the polarizing plate to which the adhesive layer is attached generally has a protective film for protecting the polarizer. Examples of the protective film include cellulose films such as cellulose triacetate, polycarbonate films, and poly Ether membranes, etc., especially cellulose membranes such as cellulose triacetate are often used.

Ionic compounds known in the past are mostly triacetic acid Cellulose produces an ionic compound that undergoes a hydrolysis reaction. On the other hand, the aforementioned ionic compound (C) hardly undergoes a hydrolysis reaction with cellulose triacetate. Therefore, even if an adhesive layer containing the ionic compound (C) is attached to the protective film, since the adhesive layer exposed to a hot and humid environment does not worry about corroding the protective film, a long-term reliability can be obtained Polarizing plate with adhesive layer.

The anionic ion-containing compound (C) is selected from bis (fluoromethyl sulfo acyl) Amides ^{_{((FSO 2) 2 N -}} ) and N, N- bis (trifluoromethanesulfonyl acyl) Amides ((CF ₃ SO _{2) 2} N ^-).

鎓陽離子、烷基銨陽離子、烷基鋶陽離子、烷基鏻離子及該等之衍生物。作為含有吡咯環之鎓陽離子，列舉：吡咯鎓陽離子、吲哚鎓陽離子、咔唑鎓陽離子等。作為衍生物，列舉於構成前述有機陽離子之環上具有1或2以上的烷基之陽離子等，該烷基之碳數通常為1至12。 Examples of the organic cation contained in the ionic compound (C) include pyridinium cation, piperidinium cation, pyrrolium cation, dihydropyrrolidinium cation, pyrrolium ring-containing onium cation, imidazolium cation, and tetrahydropyrimidinium cation. , Dihydropyrimidinium cation, pyrazolium cation, pyridine

Onium cations, alkylammonium cations, alkylammonium cations, alkylphosphonium ions and derivatives of these. Examples of the pyrrolium-containing onium cation include pyrrolium cation, indolium cation, and carbazolium cation. Examples of derivatives include cations having an alkyl group of 1 or more on the ring constituting the aforementioned organic cation, and the carbon number of the alkyl group is usually 1 to 12.

Among these, alkylammonium cations are preferred, and in particular, tetraalkylammonium cations represented by formula (c-1) are more preferred.

In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group.

Preferably, R ¹ is an alkyl group having 1 to 18 carbons, and R ² to R ⁴ are alkyl groups having 1 to 8 carbons. For obtaining an excellent adhesive due to moisture and heat resistance, it is more preferable that R ¹ is an alkyl group having 1 to 14 carbon atoms, R ² to R ⁴ is an alkyl group having 1 to 6 carbon atoms, and it is more preferable that R ¹ is The alkyl group having 1 to 10 carbon atoms and R ² to R ⁴ are alkyl groups having 1 to 6 carbon atoms. Any of the alkyl groups in R ¹ , R ² , R ³ and R ⁴ is preferably a normal alkyl group. In addition, when the alkyl group has a carbon number in the above range, it is suitable to exhibit appropriate compatibility between the (meth)acrylic polymer (A) and the ionic compound (C). Appropriate compatibility is exhibited, it exhibits good antistatic performance at the initial stage, and suppresses deterioration of antistatic performance due to bleed-out over time and deterioration of adhesion with adherend. Furthermore, it has excellent moisture and heat resistance.

Examples of the tetraalkylammonium cation represented by the above formula (c-1) include: tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrahexylammonium cation, trimethyldecylammonium cation , Triethylmethylammonium cation, tributylmethylammonium cation, tributylethylammonium cation, dodecylmethylammonium cation, etc.

The melting point of the ionic compound (C) is 25°C or higher, preferably 25°C or higher and less than 60°C, and particularly preferably 27°C or higher and less than 50°C. The ionic compound (C) with a melting point in the aforementioned range is polymerized with (meth)acrylic acid The affinity between the compound (A) is good, and the bleeding of the ionic compound (C) from the adhesive layer during long-term storage can be suppressed. The melting point can be measured by differential scanning calorimetry (DSC), for example, as described in the examples.

As the ionic compound (C), specifically, tributylmethylamine bis(trifluoromethanesulfonyl)amide and n-dodecyltrimethylaminebis(fluorosulfonyl)amide are preferable.

The content of the ionic compound in the adhesive composition of the present invention is usually more than 0 parts by mass and 15 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer (A) from the viewpoint of durability. , Preferably 0.1 to 10 parts by mass, more preferably 0.1 to 8 parts by mass.

[Silane coupling agent (D)]

The adhesive composition of the present invention may contain a silane coupling agent (D) in addition to the aforementioned compounds. The use of the silane coupling agent (D) contributes to the viewpoint of firmly adhering the adhesive layer to the substrate such as a glass plate and preventing the peeling of the polarizing plate in a high-humidity and hot environment.

Examples of the silane coupling agent (D) include vinyl trimethoxysilane, vinyl triethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacrylamide Oxypropyltrimethoxysilane, 3-methacryloxypropylmethyl diethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. containing polymerizable unsaturated groups Silane coupling agent; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyl diethoxysilane, 2-(3,4-epoxy Cyclohexyl) ethyl trimethoxysilane and other silane coupling agents containing epoxy groups; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl Group)-3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-amine Silane coupling agents containing amine groups such as propylpropyltrimethoxysilane; silane coupling agents containing halogen atoms such as 3-chloropropyltrimethoxysilane.

The content of the silane coupling agent in the adhesive composition for polarizing plates of the present invention is usually 0 to 1 part by mass, preferably 0.01 to 1 relative to 100 parts by mass of the (meth)acrylic polymer (A). The part by mass is more preferably 0.05 to 0.5 parts by mass.

[Organic Solvent (E)]

In order to adjust the coating property, the adhesive composition of the present invention preferably contains an organic solvent (E). The organic solvent is exemplified by the polymerization solvent described in the paragraph <Production conditions of (meth)acrylic polymer (A)>. For example, a polymer solution containing a (meth)acrylic polymer (A) and a polymerization solvent, a crosslinking agent (B), and an ionic compound (C) can be mixed to prepare an adhesive composition. In the adhesive composition of the present invention, the content of the organic solvent is usually 50 to 90% by mass, preferably 60 to 90% by mass.

In addition, the "solid content" in this specification means all the components except the above-mentioned organic solvent E in the contained components in the adhesive composition, and the "solid content concentration" refers to the aforementioned 100% by mass relative to the adhesive composition The ratio of solid content.

[additive]

The adhesive composition of the present invention, in addition to the above-mentioned components, may contain an antioxidant, a light stabilizer, a metal corrosion inhibitor, an adhesion-imparting agent, a plasticizer, a cross-linking agent, as long as the effect of the present invention is not impaired. One or more types of accelerators, surfactants, (meth)acrylic polymers other than the aforementioned (A), and reprocessing agents.

[Preparation of adhesive composition for polarizing plate]

The adhesive composition for polarizing plates of the present invention can be a polymer solution of a (meth)acrylic polymer (A) and a polymerization solvent, a crosslinking agent (B), an ionic compound (C), and others as necessary The ingredients are mixed and prepared in a conventional manner. For example, in the polymer solution containing the (meth)acrylic polymer (A) obtained when synthesizing the (meth)acrylic polymer (A), a crosslinking agent (B) and an ionic compound (C ) And other ingredients as necessary.

The aforementioned adhesive composition is excellent in adhesion to glass substrates, polarizing plates, etc. and durability under high temperature and high humidity, and can be suitably used for bonding of polarizing plates and glass substrates.

[Adhesive layer]

The adhesive layer of the present invention is formed of the above-mentioned adhesive composition. For example, by performing the cross-linking reaction in the adhesive composition described above, specifically, by performing a cross-linking reaction of the (meth)acrylic polymer (A) with a cross-linking agent (B), the aforementioned adhesion is obtained剂层。 Agent layer.

The formation conditions of the adhesive layer are as follows. The adhesive composition of the present invention is coated on a support, although it varies according to the type of solvent, it is usually 50 to 150°C, preferably 60 to 100°C; usually 1 to 10 minutes, preferably Dry for 2 to 7 minutes to remove the solvent, and then form a coating film. The film thickness of the dried coating film is usually 5 to 75 μm, preferably 10 to 50 μm.

The adhesive layer is preferably formed under the following conditions. After the adhesive composition of the present invention is applied to a support, and a coating film thickness is applied to the coating film formed under the above conditions, it is usually 3 days or more, preferably 7 to 10 days; usually 5 to 60 ℃, preferably 15 to 40 ℃; usually 30 to 70% RH, preferably 40 to 70% RH environment for aging. Crosslinking under the above-mentioned ripening conditions can efficiently form a network polymer.

As the coating method of the adhesive composition is a conventional method, for example, a spin coating method, a knife coating method, a roll coating method, a bar coating method, a blade coating method, and a die coating method can be used. The cloth method and the gravure coating method are methods for coating/drying the adhesive composition to a predetermined thickness.

Examples of the support and the cover film include polyester films such as polyethylene terephthalate (PET); plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

The adhesive layer formed from the adhesive composition of the present invention is preferably from 20 to 98% by mass from the viewpoint of suppressing the warpage, cohesive force, adhesive force, and re-peelability of the polarizing plate. It is preferably 30 to 98% by mass, and more preferably 35 to 95% by mass.

In addition, the surface resistance value of the adhesive layer is preferably 1.0×10 ¹⁴ Ω/□ or less, more preferably 1.0×10 ¹³ Ω/□ or less, and particularly preferably 1.0×10 ⁵ Ω/□ to 1.0×10 ¹² Ω/□. The surface resistance value shows the resistance of the surface of the adhesive layer. The smaller the value, the smaller the resistance, indicating excellent antistatic performance. The surface resistance value can be measured by the method described in the examples.

The adhesive layer of the present invention is formed by the adhesive composition containing the above-mentioned composition, which is even under such humid heat accelerating conditions as 85℃/90%RH, which is more severe than 60℃/90%RH, It still shows excellent durability.

[Adhesive sheet for polarizing plate]

The adhesive sheet for polarizing plates of the present invention has an adhesive layer formed by the adhesive composition for polarizing plates described above. As the adhesive sheet, for example, a double-sided adhesive sheet having only the above-mentioned adhesive layer, a double-sided adhesive sheet having the above-mentioned adhesive layer formed on both sides of the substrate, and having a substrate and a substrate A single-sided adhesive sheet on which the above-mentioned adhesive layer is formed on one side, and an adhesive sheet to which a peeling-treated cover film is attached on the surface of the base material of the adhesive layer on which the adhesive layer is not adhered.

Examples of the base material and cover film include polyester films such as polyethylene terephthalate (PET); plastic films such as polyolefin films such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer.

The formation conditions and gel fraction of the adhesive layer are the same as those described in the paragraph of [Adhesive Layer].

The film thickness of the adhesive layer is from the viewpoint of maintaining the adhesive performance, It is usually 5 to 75 μm, preferably 10 to 50 μm. The film thickness of the base material and the cover film is not particularly limited, but it is usually 10 to 125 μm, preferably 25 to 75 μm.

[Polarizer and laminate with an adhesive layer]

The polarizing plate with an adhesive layer of the present invention is on at least one side of the polarizing plate and the polarizing plate, and has an adhesive layer formed by the adhesive composition for polarizing plate of the present invention. In addition, in this specification, "polarizing plate" is used with the meaning containing "polarizing film".

As the polarizing plate, a conventionally known polarizing plate can be used, and for example, a polarizing plate having a polarizer protective film disposed on one side or both sides of the polarizer and the polarizer.

As the polarizer, for example, a stretched film obtained by stretching a film made of a polyvinyl alcohol-based resin containing a polarizing component is stretched. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, polyvinyl formaldehyde, polyvinyl acetaldehyde, and saponified polymer of ethylene/vinyl acetate copolymer. Examples of polarizing components include iodine and dichroic dyes.

Examples of the polarizer protective film include cellulose-containing films such as cellulose acetate such as triacetyl cellulose and cellulose diacetate; polycarbonate films; and polyether dope films. In the present invention, a cellulose film is used as a polarizer protective film, and even when an adhesive layer is formed by adhering the cellulose film, the long-term reliability, specifically, the humidity resistance is excellent.

The thickness of the polarizing plate is usually 30 to 250 μm, preferably It is 50 to 200 μm.

The method of forming the adhesive layer on the surface of the polarizing plate is not particularly limited, and an example is a method of directly coating and drying the above-mentioned adhesive composition on the surface of the polarizing plate using a bar coater or the like; The method for transferring the adhesive layer of the adhesive sheet for polarizing plate of the present invention to the surface of the polarizing plate and aging it. The conditions for drying and aging or gel fraction are the same as those described in the paragraph of [Adhesive Layer].

The thickness of the adhesive layer formed on the polarizing plate is usually 5 to 75 μm in dry film thickness, preferably 10 to 50 μm. In addition, the adhesive layer series includes only the form of forming an adhesive layer on one side of the polarizing plate and the form of forming an adhesive layer on both sides of the polarizing plate.

In addition, the polarizing plate may be a layer having another base layer such as an anti-glare layer, a retardation layer, and a viewing angle enhancement layer.

A liquid crystal element is manufactured by disposing the polarizing plate with an adhesive layer of the present invention obtained as described above on the substrate surface of a liquid crystal cell. Here, the liquid crystal cell has a structure in which the liquid crystal layer is sandwiched between two substrates.

For example, the above-mentioned polarizing plate having a polarizer and a protective film disposed on the polarizer in sequence, the above-mentioned polarizing plate, the above-mentioned protective film, an adhesive layer and a glass formed by the adhesive composition for polarizing plate of the present invention can be manufactured A laminate formed by laminating substrates.

Examples of the substrate having a liquid crystal cell include glass substrates such as alkali-free glass substrates. The thickness of the substrate is preferably 5 mm or less, and more preferably 0.05 to 2 mm.

[Example]

Hereinafter, the present invention will be further specifically explained based on the embodiments, but the present invention is not limited by these embodiments. In the descriptions of the following examples and the like, unless otherwise specified, "parts" are expressed as "parts by mass".

[Evaluation of ionic compounds]

Add 2g of water and 2g of ionic compound to a polypropylene bottle to make a test solution with a concentration of 50% by mass. Into this test solution, 0.25 g (thickness 40 μm, 40 mm×120 mm) of cellulose triacetate film (TAC film; K-10 manufactured by KONICA MINOLTA Co., Ltd.) was put and impregnated. After the polypropylene bottle was allowed to stand for 300 hours at a temperature of 85°C and a humidity of 85%, the test solution was sampled, and the concentration of acetic acid in the solution was measured by a high-speed liquid column chromatography (manufactured by Shimadzu Corporation). For analysis. The results are shown in Table 1.

The ionic compounds used in the above evaluation are as follows. In addition, the melting point of the ionic compound is measured by differential scanning calorimetry (DSC) at a rate of temperature increase from -20°C to 400°C at 10°C per minute.

As shown in Table 1, in the ionic compounds (C3) and (C4), since the concentration of acetic acid in the liquid is high, it is considered that it undergoes hydrolysis of the TAC film. On the other hand, in the ionic compounds (C1) and (C2), since the concentration of acetic acid in the liquid is low, it is considered that the degree of progress of the hydrolysis of the TAC membrane is low. Especially in the ionic compound (C1), the concentration of acetic acid in the liquid is almost the same as that of the reference water.

[GPC]

For the (meth)acrylic polymer (A), the weight average molecular weight (Mw) and the number average molecular weight (Mn) were determined by gel permeation chromatography (GPC method) under the following conditions.

‧Measurement device: HLC-8320GPC (manufactured by TOSOH Corporation)

‧Composition of GPC column: the following 4 columns (all made by TOSOH Co., Ltd.)

(1) TSKgel H×L-H (guard column)

(2) TSKgel GMH×L

(3) TSKgel GMH×L

(4) TSKgel G2500H×L

‧Flow rate: 1.0mL/min

‧Column temperature: 40℃

‧Sample concentration: 1.5% (w/v) (diluted with tetrahydrofuran)

‧Mobile phase solvent: Tetrahydrofuran

‧Conversion of standard polystyrene

[Synthesis Example A1]

In a reaction device equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube, charge 90 parts of 2-methoxyethyl acrylate, 6.5 parts of n-butyl acrylate, and 3 parts of 2-hydroxyethyl acrylate , 0.5 part of acrylic amide and 100 parts of ethyl acetate solvent, and the temperature was raised to 80°C while introducing nitrogen gas. Next, 0.1 part of 2,2'-azobisisobutyronitrile was added, and polymerization was carried out at 80°C for 6 hours under a nitrogen atmosphere. After the reaction was completed, it was diluted with ethyl acetate to prepare a polymer solution having a solid concentration of 30% by mass. The Mw of the obtained (meth)acrylic polymer A1 was 1 million, and Mw/Mn was 7.5.

[Synthesis Examples A2 and A3]

Except that the polymerizable monomer used in the polymerization reaction was changed as described in Table 2, the same procedure as in Synthesis Example A1 was carried out, and a (meth)acrylic polymer A2 or A3 containing 30% by mass of solid content was prepared. Polymer solution. The results are shown in Table 2.

[Synthesis Example A4]

In a reaction device equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube, 100 parts of toluene solvent was fed, and the temperature was raised to 90°C while introducing nitrogen. Next, 80 parts of 2-methoxyethyl acrylate, 20 parts of n-butyl acrylate, and 2 parts of 2,2'-azobisisobutyronitrile were dropped through a dropping funnel over 2 hours, further One part of 2,2'-azobisisobutyronitrile was added, and polymerization was carried out at 90°C for 6 hours under a nitrogen atmosphere. anti- After finishing the reaction, it was diluted with ethyl acetate to prepare a polymer solution with a solid concentration of 30% by mass. The obtained (meth)acrylic polymer A4-2 had an Mw of 5,000 and an Mw/Mn of 2.1.

Next, the (meth)acrylic polymer-containing polymer was added to 100 parts of the polymer solution containing a (meth)acrylic polymer A4-1 having a solid content concentration of 30% by mass, which was carried out in the same manner as in Synthesis Example A1. A4-2 has 10 parts of a polymer solution having a solid concentration of 30% by mass, and prepares a polymer solution having a solid concentration of 30% by mass.

[Synthesis Example A5]

Except that the polymerizable monomer used in the polymerization reaction was changed as described in Table 2, and 2,2'-azobisisobutyronitrile was adjusted to 0.15 parts, it was carried out in the same manner as in Synthesis Example A1. ) Acrylic polymer A5, a polymer solution with a solid concentration of 30% by mass. The results are shown in Table 2.

[Synthesis Examples A6 and A7]

Except that the polymerizable monomer used in the polymerization reaction was changed as described in Table 2, and the blending amount of ethyl acetate with the polymerizable monomer became 200 parts, it was carried out in the same manner as in Synthesis Example A1. ) A polymer solution of acrylic polymer A6 or A7 with a solid concentration of 25% by mass. The results are shown in Table 2.

[Example 1]

(1) Adjustment of adhesive composition

The (meth)acrylic polymer solution (solid content concentration 30% by mass) obtained in Synthesis Example A1 (B1) as a crosslinking agent (B): "CORONATE L" manufactured by Japan Polyurethane Industry Co., Ltd. ( a solid concentration of 75 mass%) as the ionic compound (C) of _{(C1) :( nC 4 H9)} 3 (CH 3) N + (CF 3 SO 2) 2 N -, and a silane-coupling agent (D) "KBM-403" made by Shin-Etsu Chemical Co., Ltd. was mixed to obtain an adhesive composition. Moreover, the ratio of each component is (B1) 0.4 part, (C1) 2.0 part, and (D) with respect to 100 parts of the polymer A1 contained in the (meth)acrylic-type polymer solution obtained by the synthesis example A1. ) Becomes 0.2 (either one is a solid score).

(2) Production of adhesive sheet

After removing the bubbles, apply the adhesive composition obtained in (1) above to the peeled polyethylene terephthalate film (PET film) at a liquid temperature of 25°C using a spatula, at 90°C It was dried for 3 minutes to form a coating film with a dry film thickness of 20 μm. The peeled PET film was further laminated on the opposite side of the attached surface of the aforementioned PET film, and allowed to stand for 7 days in a 23°C/50%RH environment to be matured to obtain 2 pieces. An adhesive sheet with an adhesive layer of 20 μm in thickness is sandwiched between PET films.

(3) Manufacture of polarizing plate with adhesive layer

After defoaming, on the peeled polyethylene terephthalate film (PET film), the adhesive composition obtained in (1) above was applied at a liquid temperature of 25°C using a spatula at 90°C After drying for 3 minutes, an adhesive sheet having a coating film with a dry film thickness of 20 μm was obtained. The above-mentioned sheet and the polarizing plate (thickness: 110 μm, layer structure: cellulose triacetate film/polyvinyl alcohol film/cellulose triacetate film) are pasted together by bonding the above-mentioned coating film to the polarizing plate, and on 23 It was allowed to stand for 7 days in an environment of ℃/50%RH to be matured, and a polarizing plate with an adhesive layer with a PET film, an adhesive layer with a thickness of 20 μm, and a polarizing plate was obtained.

[Examples 2 to 10, Comparative Examples 1 to 3]

In Example 1, except that the formulation composition was changed as described in Table 3, the same procedure as in Example 1 was carried out to obtain an adhesive composition, an adhesive sheet, and a polarizing plate with an adhesive layer.

And each material of Table 3 is as follows.

Crosslinking agent (B)

B1: Trimethylolpropane adduct of tolyl diisocyanate

(Made by Japan Polyurethane Industry Co., Ltd., CORONATE L, solid content concentration 75% by mass)

B2: Trimethylolpropane adduct of dimethylbenzene diisocyanate

(Synthetic Chemical Co., Ltd., TD-75, solid content concentration 75% by mass)

B3: Epoxy-based crosslinking agent (manufactured by Chongken Chemical Co., Ltd., E-5CM, solid content concentration 5 mass%)

Ionic compound (C)

Same as the ionic compounds C1 to C4 used in the aforementioned [Evaluation of Ionic Compounds]

Silane coupling agent (D)

D: Glycidoxpropyltrimethoxy silane

(Made by Shin-Etsu Chemical Industry Co., Ltd., KBM-403)

[Evaluation]

[Gel fraction]

From the adhesive sheet obtained in the example/comparative example, about 0.1 g of the adhesive layer was sampled into a sampling bottle, after adding 30 mL of ethyl acetate and shaking for 4 hours, the contents of the sampling bottle were made of 200 mesh stainless steel The gold net was filtered, and the residue on the gold net was dried at 100°C for 2 hours, and then the dry weight was measured. The gel fraction of the adhesive layer is determined by the following formula.

/Gel fraction (%)=(dry weight/adhesive layer sampling weight)×100(%)

[Surface resistance value]

The adhesive sheet obtained in the example/comparative example was cut in a size of 100 mm×100 mm to prepare a test piece. The PET film was peeled off from the adhesive sheet, and the adhesive layer was sandwiched by the circular surface electric shock and the back electrode. Apply a voltage of 100V and measure the surface resistance value after 60 seconds. In addition, the measurement was carried out in accordance with the double-ring electric shock method of JIS K6911 (1955), and the measurement of the surface resistance value used an R8252 digital potentiometer (manufactured by ADC Co., Ltd.).

[Measurement of adhesion]

The polarizing plate with an adhesive layer (laminated body containing PET film/adhesive layer/polarizing plate) obtained in the Examples/Comparative Examples was cut into a size of 70 mm×25 mm to prepare a test piece. The PET film was peeled off from the test piece, and using a laminator roll, the laminate containing the adhesive layer/polarizing plate was placed on one side of an alkali glass plate with a thickness of 2 mm to adhere the adhesive layer and the alkali glass Board bonding. The resulting laminate was kept in a sterilization kettle adjusted to 50°C/5 atm for 20 minutes. Then at 23℃/50% After being left in the RH environment for more than 2 hours, the surface of the alkali glass plate to be adhered was stretched from the bottom of the polarizing plate at a peeling angle: 180° and a peeling speed: 300 mm/min, and the adhesive strength (peel strength) was measured.

[Durability Test]

The polarizing plate with an adhesive layer (laminated body containing PET film/adhesive layer/polarizing plate) obtained in the Examples/Comparative Examples was cut into a size of 150 mm×250 mm to prepare a test piece. Peel the PET film from the test piece, and use a laminator roll to place the laminate containing the adhesive layer/polarizing plate on one side of the alkali-free glass plate with a thickness of 2 mm to adhere the adhesive layer to the alkali-free glass plate Bonding. The obtained laminate was kept in an autoclave adjusted to 50°C/5 atm for 20 minutes to prepare a test plate. Two identical test boards were made. The aforementioned test panel was placed under the condition of a temperature of 85°C (heat resistance) or the condition of a temperature of 85°C/humidity 90%RH (humidity and heat resistance) for 50 hours. Appearance defects such as foaming from the adhesive layer of the test panel, cracking of the test panel, and glass of the adhesive layer were evaluated by visual observation on the following criteria.

(Benchmark)

‧AA: 0% of the area of appearance defects

‧BB: The area of appearance defects exceeds 0% and less than 3%

‧CC: The area of appearance defects exceeds 3% and less than 5%

‧DD: more than 5% of the area with appearance defects

Claims (6)

An adhesive composition for polarizing plates, comprising: (A) a (meth)acrylic polymer obtained by polymerizing a polymerizable monomer containing 41% by mass or more of (meth)acrylate (a1), The (meth)acrylate (a1) is an alkoxyalkyl (meth)acrylate; (B) a crosslinking agent; and (C) the anion is selected from N,N-bis(fluorosulfonyl)amide Imine and N,N-bis(trifluoromethanesulfonyl)amide imide, ionic compounds whose cations are organic cations and whose melting point is above 25°C. The adhesive composition for polarizing plates as described in item 1 of the patent application scope includes a silane coupling agent (D). The adhesive composition for polarizing plates as described in Item 1 or Item 2 of the patent application scope, wherein, in the ionic compound (C), the organic cation is a tetraalkylammonium represented by the formula (c-1) cation

[In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group]. An adhesive sheet for polarizing plates having an adhesive layer formed by the adhesive composition for polarizing plates according to any one of claims 1 to 3. A polarizing plate with an adhesive layer, which has a polarizing plate and at least one side of the polarizing plate, by the adhesive composition for polarizing plate according to any one of claims 1 to 3 The adhesive layer formed. A laminated body formed by sequentially laminating a polarizer, a protective film, an adhesive layer formed by the adhesive composition for a polarizing plate as described in any one of claims 1 to 3, and a glass substrate ; Wherein, the polarizing plate has a polarizer and a protective film disposed on the polarizer.