JP6499193B2 - Pressure-sensitive adhesive composition for polarizing plate, pressure-sensitive adhesive sheet, polarizing plate with pressure-sensitive adhesive layer and laminate - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition for polarizing plate, a pressure-sensitive adhesive sheet, a polarizing plate with a pressure-sensitive adhesive layer, and a laminate.

  In recent years, the use of liquid crystal elements for displays mounted on vehicles, outdoor instruments, displays for personal computers, TVs, etc. has been expanding, and along with this, the use environment has become extremely severe. The liquid crystal element has a structure in which a liquid crystal material is sandwiched between two substrates (eg, a glass plate), and a polarizing plate is attached to the surface of the substrate via an adhesive layer. Therefore, the pressure-sensitive adhesive layer is also required to have durability under high temperature and high humidity.

  The pressure-sensitive adhesive layer for polarizing plate is usually attached to the polarizing plate in a state where the peel-treated cover film is attached to one side at the time of production of the liquid crystal element, and then the cover film is peeled off to expose the pressure-sensitive adhesive layer It is then attached to the substrate. At that time, static electricity is generated due to the high insulation properties of the cover film and the polarizing plate, which may adversely affect the alignment of the liquid crystal or damage the electronic component.

  For this reason, antistatic properties are also required for the pressure-sensitive adhesive layer for polarizing plates, and an ionic compound is added to the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer as a pressure-sensitive adhesive layer for polarizing plates having antistatic properties. The technology to be included is reported.

  For example, Patent Document 1 discloses an adhesive containing an acrylic resin obtained by polymerizing a specific (meth) acrylic acid ester, an ionic compound having an organic cation and being solid at room temperature, and a crosslinking agent. An agent composition is described. Patent Document 2 describes a pressure-sensitive adhesive composition containing an ionic compound having a melting point of 50 ° C. or more and a base polymer having a glass transition temperature of 0 ° C. or less.

JP, 2010-66756, A JP, 2009-19162, A

  In general, a polarizing plate often has a protective film for protecting a polarizer. The pressure-sensitive adhesive layer is formed in contact with the protective film. However, according to the study of the present inventors, the polymer component constituting the protective film causes a hydrolysis reaction in the wet heat environment by the ionic compound contained in the pressure-sensitive adhesive layer to corrode the polarizing plate, etc. , It turned out that a problem arises in long-term reliability. In addition, it is required that the problems described above do not occur even under more severe conditions than the conventional long-term tests due to the further thinning and use range of further members in recent years.

  The object of the present invention is to provide a pressure-sensitive adhesive composition for polarizing plate capable of forming a pressure-sensitive adhesive layer having excellent antistatic performance and durability under high temperature and high humidity, and an adhesive formed from the above composition An adhesive sheet having an agent layer, an adhesive layer-attached polarizing plate having the adhesive layer, and a laminate having the adhesive layer.

  The present inventors diligently studied to solve the above problems. As a result, when the (meth) acrylic polymer obtained from the polymerizable monomer containing a specific amount of (meth) acrylic acid ester, the crosslinking agent, and the specific ionic compound are used in combination, the above problems It has been found that the present invention can be solved, and the present invention has been completed.

The present invention is, for example, the following [1] to [6].
[1] (A) A (meth) acrylic polymer obtained by polymerizing a polymerizable monomer containing 41% by mass or more of a (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group When,
(B) a crosslinking agent,
(C) An ionic compound wherein the anion is selected from N, N-bis (fluorosulfonyl) imide and N, N-bis (trifluoromethanesulfonyl) imide, the cation is an organic cation, and the melting point is 25 ° C. or higher A pressure-sensitive adhesive composition for a polarizing plate containing

[2] The pressure-sensitive adhesive composition for a polarizing plate according to [1], further containing a silane coupling agent (D).
[3] The pressure-sensitive adhesive composition for a polarizing plate according to [1] or [2], wherein the organic cation in the ionic compound (C) is a tetraalkylammonium cation represented by the formula (c-1).

［式（ｃ−１）中、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立にアルキル基である。］
［４］ ［１］〜［３］のいずれか１項に記載の偏光板用粘着剤組成物より形成された粘着剤層を有する偏光板用粘着シート。

[In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group. ]
[4] A pressure-sensitive adhesive sheet for a polarizing plate having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for a polarizing plate according to any one of [1] to [3].

  [5] Pressure-sensitive adhesive having a polarizing plate and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for polarizing plate according to any one of [1] to [3] on at least one surface of the polarizing plate Agent layer attached polarizing plate.

  [6] A polarizing plate has a polarizer and a protective film disposed on the polarizer, and the polarizer, the protective film, the adhesive for polarizing plate according to any one of [1] to [3]. A laminated body in which a pressure-sensitive adhesive layer formed of the agent composition and a glass substrate are laminated in this order.

  According to the present invention, a pressure-sensitive adhesive composition for a polarizing plate capable of forming a pressure-sensitive adhesive layer excellent in antistatic performance and having durability under high temperature and high humidity, and adhesion formed from the composition The adhesive sheet which has an agent layer, the polarizing plate with an adhesive layer which has the said adhesive layer, and the laminated body which has the said adhesive layer can be provided.

Hereinafter, the pressure-sensitive adhesive composition for a polarizing plate, the pressure-sensitive adhesive sheet for a polarizing plate, the polarizing plate with a pressure-sensitive adhesive layer, and the laminate of the present invention will be described. Hereinafter, the pressure-sensitive adhesive composition for polarizing plate of the present invention is simply referred to as "pressure-sensitive adhesive composition", and the pressure-sensitive adhesive sheet for polarizing plate of the present invention is also simply referred to as "pressure-sensitive adhesive sheet".
In the present specification, acrylic and methacrylic are also collectively referred to as "(meth) acrylic".

[Pressure-sensitive adhesive composition for polarizing plate]
The pressure-sensitive adhesive composition for a polarizing plate of the present invention contains a (meth) acrylic polymer (A), a crosslinking agent (B), and an ionic compound (C) described below. The pressure-sensitive adhesive composition may optionally contain a silane coupling agent (D), and may contain an organic solvent (E).

[(Meth) acrylic polymer (A)]
The (meth) acrylic polymer (A) is a polymer of a polymerizable monomer containing a (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group, and the above-mentioned polymerizable monomer Obtained by polymerizing. Thus, the (meth) acrylic polymer (A) preferably has a structural unit derived from (a1).

  The polymerizable monomer may be only a (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group, and, together with the (a1), a polyoxyalkylene group, an alkoxyalkyl group and a crosslinkable group And the crosslinkable group-containing monomer (a3), and at least one other monomer selected from the other monomers (a4). For example, the polymerizable monomer containing said (a1)-(a3) and containing said (a4) as needed is mentioned.

  Here, the crosslinkable group is a group capable of introducing a crosslinking point which can be crosslinked by the crosslinking agent (B) into the (meth) acrylic polymer (A), and a hydroxyl group, a carboxyl group, etc. It can be mentioned.

  Hereinafter, the (meth) acrylic acid ester (a1) is also referred to as “monomer (a1)”, and the (meth) acrylic acid ester (a2) is also referred to as “monomer (a2)”, and contains a crosslinkable group The monomer (a3) is also referred to as "monomer (a3)", and the other monomer (a4) is also referred to as "monomer (a4)".

<< Monomer (a1) >>
The monomer (a1) is a (meth) acrylic acid ester having a polyoxyalkylene group or an alkoxyalkyl group. The monomer (a1) is preferably a (meth) acrylic acid ester having no crosslinkable group.

The monomer (a1) is represented by, for example, the formula (a-1).
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 the 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 1-20, more preferably 1-4, still more preferably 1-2.

As a monomer (a1), the alkoxy alkyl (meth) acrylate and the alkoxy polyalkylene glycol mono (meth) acrylate are mentioned, for example.
Examples of alkoxyalkyl (meth) acrylates include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (3-ethoxypropyl (meth) acrylate Examples include meta) acrylate, 4-methoxybutyl (meth) acrylate and 4-ethoxybutyl (meth) acrylate.

  As alkoxypolyalkylene glycol mono (meth) acrylate, for example, methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meth) acrylate, Methoxy triethylene glycol mono (meth) acrylate is mentioned.

Among these, as the monomer (a1), an alkoxyalkyl (meth) acrylate in which R ^{2 in} the formula (a-1) is an alkoxyalkyl group is preferable from the viewpoint of reactivity.
A monomer (a1) may be used individually by 1 type, and may use 2 or more types.

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

  When the amount of the monomer (a1) used is 41% by mass or more, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the (meth) acrylic polymer (A) exhibits high polarity and is polarized Excellent adhesion to plates and substrates (especially glass plates). Therefore, the pressure-sensitive adhesive layer does not float or peel from the polarizing plate or the substrate even under high temperature and high humidity heat, and a pressure-sensitive adhesive layer excellent in durability can be obtained. In addition, reworkability is good because of excellent adhesion to the substrate, and adhesion of the pressure-sensitive adhesive layer to the punching blade, the peripheral polarizing plate, and the like hardly occurs, and the workability is excellent. When the amount of the monomer (a1) used is 50% by mass or more, the above effect is more remarkable. When the amount of the monomer (a1) used is within the above range, the affinity between the (meth) acrylic polymer (A) and the ionic compound (C) described later is good, and the ionic compound (C) Bleed can be suppressed.

<< Monomer (a2) >>
The monomer (a2) is a (meth) acrylic acid ester having neither a polyoxyalkylene group, an alkoxyalkyl group nor a crosslinkable group. The (meth) acrylic polymer (A) preferably has a structural unit derived from (a2).
The monomer (a2) is represented, for example, by the formula (a-2).
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 having neither a polyoxyalkylene group, an alkoxyalkyl group nor a crosslinkable group.

Examples of the organic group in R ⁶ include an alicyclic group such as an alkyl group and a cycloalkyl group, an aryl group, an aralkyl group, an aryloxyalkyl group, and an N-monoalkyl substituted aminoalkyl group. The carbon number of the alkyl group is usually 1 to 24. Carbon number of alicyclic groups, such as a cycloalkyl group, is 3-15 normally. The carbon number of the aryl group is usually 6 to 10. The aralkyl group usually comprises an alkylene group having 1 to 6 carbon atoms and an aryl group having 6 to 10 carbon atoms. The aryloxyalkyl group usually comprises an alkyleneoxy group having 1 to 6 carbon atoms and an aryl group having 6 to 10 carbon atoms. The carbon number of the N-monoalkyl substituted aminoalkyl group is usually 1-12.

  Examples of the monomer (a2) include alicyclic group-containing (meth) acrylic acid esters such as (meth) acrylic acid alkyl esters and (meth) acrylic acid cycloalkyl esters, (meth) acrylic acid aryl esters, And (meth) acrylic acid aralkyl esters, (meth) acrylic acid aryloxyalkyl esters, and N-monoalkyl-substituted aminoalkyl group-containing (meth) acrylates.

  Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate and isobutyl (meth) Acrylate, tert-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, lauryl (meth) a Relate, stearyl (meth) acrylate, isostearyl (meth) acrylate.

  Examples of alicyclic group-containing (meth) acrylic acid esters such as (meth) acrylic acid cycloalkyl esters, (meth) acrylic acid aryl esters and (meth) acrylic acid aralkyl esters include, for example, cyclohexyl (meth) acrylate and isobornyl ( Examples include meta) acrylate, phenyl (meth) acrylate and benzyl (meth) acrylate.

  Examples of (meth) acrylic acid aryloxyalkyl esters include phenoxymethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-tolyloxyethyl (meth) acrylate, xylyloxymethyl (meth) acrylate, and naphthyl. Oxymethyl (meth) acrylate is mentioned.

As the N-monoalkyl substituted aminoalkyl group-containing (meth) acrylate, for example, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) And acrylates.
The monomers (a2) may be used alone or in combination of two or more.

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

<< Monomer (a3) >>
The monomer (a3) is a monomer containing a crosslinkable group. The (meth) acrylic polymer (A) may have a structural unit derived from (a3).
By using the monomer (a3) as the polymerizable monomer constituting the (meth) acrylic polymer (A), a crosslinking point which can be crosslinked by the crosslinking agent (B) can be a (meth) acrylic polymer (A) can be introduced.

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

The organic group in R ^8, hydroxyalkyl group having 1 to 12 carbon atoms, and a carboxyl group-substituted aliphatic group.

As a monomer (a3), a hydroxyl-containing (meth) acrylate and a carboxyl group-containing (meth) acrylate are mentioned, for example.
Examples of the hydroxyl group-containing (meth) acrylate include hydroxyalkyl (meth) acrylate and the like, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate are mentioned.

Examples of carboxyl group-containing (meth) acrylates include β-carboxyethyl (meth) acrylate and 5-carboxypentyl (meth) acrylate.
As a monomer (a3), the ethylenically unsaturated carboxylic acid can also be mentioned besides the compound represented by Formula (a-3). Examples of the ethylenically unsaturated carboxylic acids include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid.
The monomer (a3) may be used alone or in combination of two or more.

  The amount of the monomer (a3) used in 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A) is preferably from the viewpoint of expression of durability and stress relaxation characteristics by appropriate crosslinking. Is 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.

<< Monomer (a4) >>
The (meth) acrylic polymer (A) may have a structural unit derived from (a4).
As the monomer (a4), for example, 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, α-methyl Styrene-based monomers such as styrene; diene-based monomers such as butadiene, isoprene and chloroprene; nitrile-based monomers such as (meth) acrylonitrile; and amide group-containing monomers.
As the amide group-containing monomer, for example, N-mono such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-hexyl (meth) acrylamide and the like Alkyl substituted acrylamide; N, N-dialkyl substituted acrylamides, such as N, N- dimethyl acrylamide, N, N- dimethyl methacrylamide, are mentioned.
A monomer (a4) may be used individually by 1 type, and 2 or more types may be used.

<< Production conditions of (meth) acrylic polymer (A) >>
The (meth) acrylic polymer (A) can be produced by, for example, conventionally known polymerization methods such as solution polymerization method, bulk polymerization method, emulsion polymerization method and suspension polymerization method, and among them, the solution polymerization method Is preferred. Specifically, a polymerization solvent and a polymerizable monomer are charged in a reaction vessel, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the reaction start temperature is usually 40 to 100 ° C., preferably 50. The reaction system is maintained at a temperature of 80 ° C., usually 50 to 90 ° C., preferably 60 to 90 ° C., and reacted for 4 to 20 hours.

Examples of the polymerization initiator include an azo initiator and a peroxide polymerization initiator.
As an azo 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-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbo) Nitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'- Azobis (N, N′-dimethylene isobutyl amidine), 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azo Di (isobutylamido) dihydrate, 4,4'-azobis (4-cyanopentanoic acid), 2,2'-azobis (2-cyanopropanol), dimethyl-2,2'-azobis (2-methyl propionate) And azo compounds such as 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide].

  As a peroxide type polymerization initiator, for example, t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate , Di-2-ethylhexyl peroxydicarbonate, t-butylperoxy bivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-bis (4,4-di-t-butylperoxycyclohexyl) propane Di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl ) Propane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) Butane, 2,2-bis (4,4-di -t- octylperoxycarbonyl cyclohexyl), and butane.

The polymerization initiator may be used alone or in combination of two or more.
The addition of multiple polymerization initiators during polymerization is also not limited.
The polymerization initiator is usually in the range of 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass with respect to 100 parts by mass of the polymerizable monomer forming the (meth) acrylic polymer (A). Used in quantity. In addition, during the polymerization reaction, a polymerization initiator, a chain transfer agent, a polymerizable monomer, and a polymerization solvent may be added as appropriate.

As a polymerization solvent used for solution polymerization, for example, aromatic hydrocarbons such as benzene, toluene, xylene and the like; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane and the like; cyclopentane, Alicyclic hydrocarbons such as cyclohexane, cycloheptane and cyclooctane; diethylether, diisopropylether, 1,2-dimethoxyethane, dibutylether, tetrahydrofuran, dioxane, anisole, phenylethylether, ethers such as diphenylether; chloroform, Halogenated hydrocarbons such as carbon tetrachloride, 1,2-dichloroethane and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate and methyl propionate; acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone And ketones such as cyclohexanone; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; sulfoxides such as dimethyl sulfoxide and sulfolane Etc.
The polymerization solvents may be used alone or in combination of two or more.

<< Physical properties and content of (meth) acrylic polymer (A) >>
The (meth) acrylic polymer (A) has, for example, a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC method), in terms of polystyrene, generally at least 400,000, preferably It is a polymer (A-1) of 450,000 to 2,000,000, more preferably 600,000 to 1,800,000, further preferably 800,000 to 1,800,000. It is preferable at the point of the durability of an adhesive layer that Mw is more than the said lower limit. It is preferable at the point of the coating property of an adhesive composition as Mw is below the said upper limit.

  The polymer (A-1) has a molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) measured by GPC method, usually 2 to 60, preferably 3 to 45, more preferably 3 to 3 It is twenty. It is preferable at the point of the adhesive expression to a board | substrate or a polarizing plate etc. as Mw / Mn is more than the said lower limit. It is preferable at the point which is excellent in heat resistance and durable maintenance that Mw / Mn is below the said upper limit.

  The (meth) acrylic polymer (A) can be composed of only the polymer (A-1). The (meth) acrylic polymer (A) may be a blend of the above-mentioned polymer (A-1) and a low molecular weight polymer (A-2). Use of the blend is preferable in terms of the improvement of wettability and the improvement of stress relaxation.

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, still more preferably 100 parts by mass of the polymer (A-1). 1 to 30 parts by mass.
The Mw of the low molecular weight polymer (A-2) measured by the GPC method is, in terms of polystyrene, 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, for example, a differential scanning calorimeter, and from the monomer units constituting the copolymer and the content ratio thereof, Fox It can be calculated by the formula of For example, the (meth) acrylic polymer (A) can be synthesized such that the glass transition temperature (Tg) determined by the Fox equation is usually −70 to 10 ° C., preferably −60 to 0 ° C. . The glass transition temperature of the homopolymer comprising each monomer in the Fox formula can be, for example, the value described in Polymer Handbook Forth Edition (Wiley-Interscience 2003).

[Crosslinking agent (B)]
The pressure-sensitive adhesive composition of the present invention contains a crosslinking agent (B). The crosslinking agent (B) is suitably selected by the crosslinkable group which may be introduce | transduced into a (meth) acrylic-type 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 the crosslinking agent (B), a crosslinked product (network polymer) can be formed, and a pressure-sensitive adhesive layer excellent in heat resistance can be obtained.

The crosslinking agent (B) may be used alone or in combination of two or more.
In the pressure-sensitive adhesive composition of the present invention, the content of the crosslinking agent (B) is appropriately selected according to the (meth) acrylic polymer (A), and 100 parts by mass of the (meth) acrylic polymer (A) It is preferable that it is 0.01-25 mass parts with respect to. More preferably, when the Mw of the (meth) acrylic polymer (A-1) is 800,000 or more, the content of the crosslinking agent (B) is 0.01 to 3 parts by mass, and 400 to 800,000. In the case of 5 to 25 parts by mass.

  When Mw of (A-1) is 800,000 or more, by blending the crosslinking agent (B) within the above range, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition exhibits stress relaxation characteristics and is sufficiently Heat resistance can be obtained. In addition, it is excellent in flexibility and adhesion. When Mw of (A-1) is 400,000 or more and less than 800,000, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition contains the aggregation of the pressure-sensitive adhesive layer by blending the crosslinking agent (B) within the above range. Sufficient heat resistance can be obtained by force. Further, the sticking out of the adhesive layer from the substrate or the base material, adhesion to the punching blade and the peripheral polarizing plate is suppressed, and the workability is excellent.

  As an isocyanate compound, the isocyanate compound in which the number of isocyanate groups in 1 molecule is 2 or more is used normally, Preferably it is 2-8, More preferably, it is 3-6. When the number of isocyanate groups is in the above range, it is preferable in terms of the crosslinking reaction efficiency of the (meth) acrylic polymer (A) and the isocyanate compound, and in terms of maintaining the flexibility of the pressure-sensitive adhesive layer.

  Examples of the diisocyanate compound having 2 isocyanate groups per molecule include aliphatic diisocyanates, alicyclic diisocyanates and aromatic diisocyanates. As aliphatic diisocyanates, ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, 2,2,4-trimethyl isocyanate Aliphatic diisocyanates having 4 to 30 carbon atoms such as 1,6-hexamethylene diisocyanate can be mentioned. Examples of alicyclic diisocyanates include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, and the like. Family diisocyanates. Examples of the aromatic diisocyanate include aromatic diisocyanates having 8 to 30 carbon atoms, such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthyl diisocyanate, diphenyl ether diisocyanate, diphenyl methane diisocyanate, diphenyl propane diisocyanate, and the like.

  Examples of the isocyanate compound having 3 or more isocyanate groups in one molecule include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate. Specifically, 2,4,6- triisocyanate toluene, 1,3,5-triisocyanate benzene, 4,4 ', 4 "-triphenylmethane triisocyanate is mentioned.

  In addition, as the isocyanate compound, for example, a multimer (for example, dimer or trimer, biuret body, isocyanurate body) or derivative (for example, polyhydric alcohol) of the above-mentioned isocyanate compound having 2 or 3 or more isocyanate groups Addition reaction products with two or more molecules of diisocyanate compounds), polymers. Examples of the polyhydric alcohol in the derivative include low molecular weight polyhydric alcohols such as tri- or higher alcohols such as trimethylolpropane, glycerin and pentaerythritol; and high molecular weight polyhydric alcohols such as polyether polyols, Polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols are mentioned.

  As such an isocyanate compound, for example, trimer of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, biuret or isocyanurate of hexamethylene diisocyanate or tolylene diisocyanate, trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate (For example, trimolecular adduct of tolylene diisocyanate or xylylene diisocyanate), reaction product of trimethylolpropane with hexamethylene diisocyanate (for example, trimolecular adduct of hexamethylene diisocyanate), polyether polyisocyanate, Polyester polyisocyanate is mentioned.

  Among isocyanate compounds, the reaction product of trimethylolpropane with tolylene diisocyanate or xylylene diisocyanate in that it can improve the aging property and light leakage performance (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd., Soken Chemical ( TD-75, etc., Inc., and isocyanurate of hexamethylene diisocyanate or tolylene diisocyanate (TSE-100, manufactured by Asahi Kasei Kogyo Co., Ltd., 2050, manufactured by Nippon Polyurethane Industry Co., Ltd.) are preferable.

  Examples of the epoxy compound include compounds having two or more epoxy groups in the molecule, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexane Diol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′- And diamines (glycidyl aminomethyl). Examples of commercially available products include E-5 CM manufactured by Soken Chemical Co., Ltd., and E-5 XM manufactured by Soken Chemical Co., Ltd.

  As the metal chelate compound, for example, alkoxide, acetylacetone, ethyl acetoacetate and the like are coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. Compounds are mentioned. Specific examples thereof include aluminum isopropylate, aluminum secondary butyrate, aluminum ethylacetoacetate / diisopropylate, aluminum trisethylacetoacetate and aluminum trisacetylacetonate.

[Ionic Compound (C)]
The pressure-sensitive adhesive composition of the present invention comprises an anion selected from N, N-bis (fluorosulfonyl) imide and N, N-bis (trifluoromethanesulfonyl) imide, and an organic cation, and has a melting point of 25 ° C. or higher Contains an ionic compound (C).

  When the pressure-sensitive adhesive composition contains the ionic compound (C), the surface resistance value of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition can be reduced, and a pressure-sensitive adhesive layer having antistatic performance can be obtained.

  In addition, in general, a polarizing plate to which the pressure-sensitive adhesive layer is attached often has a protective film for protecting a polarizer, and as the protective film, a cellulose film such as triacetyl cellulose, A polycarbonate film, a polyether sulfone film, etc. are mentioned, Especially cellulose films, such as a triacetyl cellulose, are used well.

  The conventionally known ionic compounds contain many ionic compounds that cause a hydrolysis reaction with triacetyl cellulose, while the ionic compounds (C) hardly cause a hydrolysis reaction with triacetyl cellulose. From this, even if the pressure-sensitive adhesive layer containing the ionic compound (C) is attached onto the protective film, the pressure-sensitive adhesive layer exposed to the moist heat environment is not likely to corrode the protective film, A polarizing plate with a pressure-sensitive adhesive layer excellent in long-term reliability can be obtained.

The anion contained in the ionic compound (C) is N, N-bis (fluorosulfonyl) imide ((FSO ₂ ) ₂ N ⁻ ) and N, N-bis (trifluoromethanesulfonyl) imide ((CF ₃ SO ₂ ) ₂ N ^-) is selected from the group consisting of.

  Examples of the organic cation contained in the ionic compound (C) include pyridinium cation, piperidinium cation, pyrrolidinium cation, pyrrolin cation, cation having a pyrrole ring, imidazolium cation, tetrahydropyrimidinium cation, dihydropyri There may be mentioned midinium cations, pyrazolium cations, pyrazolinium cations, alkyl ammonium cations, alkyl sulfonium cations, alkyl phosphonium cations and their derivatives. Examples of the cation having a pyrrole ring include pyrrole cation, indole cation, carbazole cation and the like. As a derivative, the cation etc. which have one or two or more alkyl groups on the ring which comprises the said organic cation are mentioned, Carbon number of the said alkyl group is 1-12 normally.

  Among these, an alkyl ammonium cation is preferable, and in particular, a tetraalkyl ammonium cation represented by the formula (c-1) is more preferable.

式（ｃ−１）中、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立にアルキル基である。

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 carbon atoms, and R ^{2 to} R ⁴ are an alkyl group having 1 to 8 carbon atoms. More preferably, R ¹ is an alkyl group having 1 to 14 carbon atoms, and R ^{2 to} R ⁴ are an alkyl group having 1 to 6 carbon atoms, more preferably because a pressure-sensitive adhesive layer excellent in moisture and heat resistance is obtained. And R ¹ is an alkyl group having 1 to 10 carbon atoms, and R ^{2 to} R ⁴ are an alkyl group having 1 to 6 carbon atoms. It is preferable that the alkyl group in R < ¹ >, R < ² >, R < ³ > and R < ⁴ > is all n-alkyl groups. In addition, it is desirable that the alkyl group has a carbon number in the above range in order to express appropriate compatibility between the (meth) acrylic polymer (A) and the ionic compound (C). By exhibiting appropriate compatibility, an initial good antistatic performance is exhibited, and deterioration of the antistatic performance due to bleeding over time and adhesion deterioration with an adherend are suppressed. Furthermore, it is excellent in heat and humidity resistance.

  As the tetraalkyl ammonium cation represented by the above formula (c-1), tetramethyl ammonium cation, tetraethyl ammonium cation, tetrabutyl ammonium cation, tetrahexyl ammonium cation, trimethyldecyl ammonium cation, triethyl methyl ammonium cation, tributyl methyl ammonium Cation, tributylethyl ammonium cation, dodecyl trimethyl ammonium cation and the like can be mentioned.

  The melting point of the ionic compound (C) is 25 ° C. or more, preferably 25 ° C. or more and less than 60 ° C., particularly preferably 27 ° C. or more and less than 50 ° C. The ionic compound (C) having a melting point in the above range has good affinity with the (meth) acrylic polymer (A), and suppresses bleeding of the ionic compound (C) from the adhesive layer during long-term storage Can. The melting point can be measured, for example, by differential scanning calorimetry (DSC) by the method described in the examples.

  Specifically, as the ionic compound (C), tributylmethylammonium bis (trifluoromethanesulfonyl) imide and n-dodecyltrimethylammonium bis (fluorosulfonyl) imide are preferable.

  The content of the ionic compound (C) in the pressure-sensitive adhesive composition of the present invention is usually more than 0 parts by mass and 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer (A) from the viewpoint of durability. Or less, preferably 0.1 to 10 parts by mass, more preferably 0.1 to 8 parts by mass.

[Silane coupling agent (D)]
The pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent (D) in addition to the above compounds. By using the silane coupling agent (D), the pressure-sensitive adhesive layer can be firmly adhered to a substrate such as a glass plate, which can contribute to preventing peeling of the polarizing plate under a high humidity and heat environment.

  As the silane coupling agent (D), for example, vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, Polymerizable unsaturated group-containing silane coupling agents such as 3-methacryloxypropyltriethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane Epoxy group-containing silane coupling agents such as 3-glycidoxypropylmethyldiethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyl Pirtriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,1 Amino group-containing silane coupling agents such as 3-dimethyl-butylidene) propylamine and N-phenyl-3-aminopropyltrimethoxysilane; halogen-containing silane coupling agents such as 3-chloropropyltrimethoxysilane.

  The content of the silane coupling agent (D) in the pressure-sensitive adhesive composition for a polarizing plate of the present invention is usually 0 to 1 parts by mass, preferably 0 based on 100 parts by mass of the (meth) acrylic polymer (A). 0.01 to 1 part by mass, more preferably 0.05 to 0.5 parts by mass.

[Organic solvent (E)]
The pressure-sensitive adhesive composition of the present invention preferably contains an organic solvent (E) in order to adjust its coatability. Examples of the organic solvent include the polymerization solvents described in the section “Production conditions of (meth) acrylic polymer (A)”. For example, a pressure-sensitive adhesive composition can be prepared by mixing a polymer solution containing a (meth) acrylic polymer (A) and a polymerization solvent, a crosslinking agent (B), and an ionic compound (C). . In the pressure-sensitive 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, in this specification, "solid content" means all the components except the said organic solvent (E) among the components in an adhesive composition, and "solid content concentration" means the adhesive composition 100. The ratio of said solid content to mass% is said.

[Additive]
The pressure-sensitive adhesive composition of the present invention is, in addition to the above components, an antioxidant, a light stabilizer, a metal corrosion inhibitor, a tackifier, a plasticizer, a crosslinking accelerator, and a surfactant within the range not impairing the effects of the present invention. It may contain one or more selected from agents, (meth) acrylic polymers other than the above (A), and rework agents.

[Preparation of pressure-sensitive adhesive composition for polarizing plate]
The pressure-sensitive adhesive composition for a polarizing plate of the present invention comprises a (meth) acrylic polymer (A), a crosslinking agent (B), an ionic compound (C), and, if necessary, other components, It can be prepared by mixing according to known methods. For example, a 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, if necessary, blending other components.
The pressure-sensitive adhesive composition is excellent in adhesion to a glass substrate, a polarizing plate or the like and durability under high temperature and high humidity, and thus can be suitably used for bonding the polarizing plate and the glass substrate.

[Adhesive layer]
The pressure-sensitive adhesive layer of the present invention is formed from the above-mentioned pressure-sensitive adhesive composition. For example, by advancing the crosslinking reaction in the above-mentioned pressure-sensitive adhesive composition, specifically, the above-mentioned pressure-sensitive adhesive layer can be obtained by crosslinking the (meth) acrylic polymer (A) with the crosslinking agent (B) .

  The conditions for forming the pressure-sensitive adhesive layer are, for example, as follows. The pressure-sensitive adhesive composition of the present invention is coated on a support, and usually dried at 50 to 150 ° C., preferably 60 to 100 ° C., usually 1 to 10 minutes, preferably 2 to 7 minutes. The solvent is removed to form a coating. The thickness of the dried coating is usually 5 to 75 μm, preferably 10 to 50 μm.

  The pressure-sensitive adhesive layer is preferably formed under the following conditions. The pressure-sensitive adhesive composition of the present invention is coated on a support, and a cover film is attached on a coating film formed under the above conditions, usually 3 days or more, preferably 7 to 10 days, usually 5 to 60 ° C. Preferably, curing is performed in an environment of 15 to 40 ° C., usually 30 to 70% RH, preferably 40 to 70% RH. When crosslinking is performed under the above-described aging conditions, formation of a crosslinked product (network polymer) can be efficiently performed.

  The pressure-sensitive adhesive composition may be applied to a predetermined thickness by a known method such as spin coating, knife coating, roll coating, bar coating, blade coating, die coating or gravure coating. A method of coating and drying can be used.

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

  The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention preferably has a gel fraction of 20 to 98% by mass, more preferably from the viewpoint of distortion suppression of a polarizing plate, cohesion, adhesion and removability. Is 30 to 98% by mass, more preferably 35 to 95% by mass.

Further, the surface resistivity of the pressure-sensitive adhesive layer is preferably 1.0 × 10 ¹⁴ Ω / sq or less, more preferably 1.0 × 10 ¹³ Ω / sq or less, particularly preferably 1.0 × 10 ⁵ to 1 It is .0 × 10 ¹² Ω / □. The surface resistance value indicates the electrical resistance of the surface of the pressure-sensitive adhesive layer, and the smaller the value, the smaller the electrical resistance and the better the antistatic performance. The surface resistance value can be measured by the method described in the examples.

  Since the pressure-sensitive adhesive layer of the present invention is formed from the pressure-sensitive adhesive composition having the above-described constitution, it is excellent even under moist heat promoting conditions of 85 ° C./90% RH stricter than 60 ° C./90% RH. It shows durability.

[Adhesive sheet for polarizing plate]
The pressure-sensitive adhesive sheet for a polarizing plate of the present invention has a pressure-sensitive adhesive layer formed of the above-described pressure-sensitive adhesive composition for a polarizing plate. As the pressure-sensitive adhesive sheet, for example, a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, a double-sided pressure-sensitive adhesive sheet having the substrate and the pressure-sensitive adhesive layer formed on both sides of the substrate, a substrate, and one of the substrates The adhesive sheet in which the single-sided adhesive sheet which has the said adhesive layer formed in the surface and the cover film by which the peeling process was carried out on the surface which is not in contact with the base material of the adhesive layer of these adhesive sheets is mentioned.

  As a base material and a cover film, For example, Polyester film, such as a polyethylene terephthalate (PET); Plastic film, such as polyolefin films, such as polyethylene, a polypropylene, an ethylene-vinyl acetate copolymer, etc. are mentioned.

The formation conditions and gel fraction of the pressure-sensitive adhesive layer are the same as the conditions described in the section of [pressure-sensitive adhesive layer].
The thickness of the pressure-sensitive adhesive layer is usually 5 to 75 μm, preferably 10 to 50 μm, from the viewpoint of maintaining the adhesion performance. Although the film thickness of a base material and a cover film is not specifically limited, Usually, 10-125 micrometers, Preferably it is 25-75 micrometers.

[Polarizing plate with pressure-sensitive adhesive layer and laminate]
The polarizing plate with a pressure-sensitive adhesive layer of the present invention has a polarizing plate and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for a polarizing plate of the present invention on at least one surface of the polarizing plate. In the present specification, “polarizing plate” is used to mean including “polarizing film”.

As a polarizing plate, a conventionally well-known polarizing plate can be used, For example, the polarizing plate which has a polarizer and the polarizer protective film arrange | positioned on the single side | surface or both surfaces of the said polarizer is mentioned.
As a polarizer, the stretched film obtained by making a film which consists of polyvinyl alcohol-type resin contain a polarization | polarized-light component and extending | stretching is mentioned, for example. Examples of polyvinyl alcohol resins include polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and saponified ethylene-vinyl acetate copolymer. The polarization component includes, for example, iodine or a dichroic dye.

  Examples of the polarizer protective film include films made of cellulose such as acetyl cellulose such as triacetyl cellulose and diacetyl cellulose, polycarbonate films, and polyether sulfone films. In the present invention, even when a cellulose film is used as a polarizer protective film and a pressure-sensitive adhesive layer is formed in contact with the cellulose film, long-term reliability, specifically, moisture and heat resistance is excellent.

The thickness of the polarizing plate is usually 30 to 250 μm, preferably 50 to 200 μm.
There is no particular limitation on the method of forming the pressure-sensitive adhesive layer on the surface of the polarizing plate, and the above-mentioned pressure-sensitive adhesive composition is directly coated on the surface of the polarizing plate using a bar coater or the like, dried and aged. The method of transcribe | transferring the adhesive layer which this has to the polarizing plate surface, and ripening is mentioned. The conditions for drying and aging, the gel fraction and the like are the same as the conditions described in the [adhesive layer].

  The thickness of the pressure-sensitive adhesive layer formed on the polarizing plate is usually 5 to 75 μm, preferably 10 to 50 μm, in dry thickness. The pressure-sensitive adhesive layer may be formed on at least one surface of the polarizing plate, and the pressure-sensitive adhesive layer may be formed on only one side of the polarizing plate, or the pressure-sensitive adhesive layer may be formed on both sides of the polarizing plate. Can be mentioned.

In addition, layers having other functions such as an antiglare layer, a retardation layer, and a viewing angle improvement layer may be stacked on the polarizing plate.
A liquid crystal element is manufactured by providing the adhesive layer-attached polarizing plate 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 a liquid crystal layer is sandwiched between two substrates.

  For example, the polarizing plate has a polarizer and a protective film disposed on the polarizer, and the polarizer, the protective film, a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for polarizing plate of the present invention, A laminated body in which glass substrates are laminated in this order can be manufactured.

  As a substrate which a liquid crystal cell has, glass plates, such as an alkali free glass plate, are mentioned, for example. The thickness of the substrate is preferably 5 mm or less, more preferably 0.05 to 2 mm.

  Hereinafter, the present invention will be more specifically described based on examples, but the present invention is not limited to these examples. In the description of the following examples etc., unless otherwise stated, "part" shows a "mass part".

[Evaluation of ionic compounds]
2 g of water and 2 g of an ionic compound were added to a polypropylene bottle to prepare a test solution having a concentration of 50% by mass. Into this test solution, 0.25 g (thickness 40 μm, 40 mm × 120 mm) of triacetyl cellulose film (TAC film; K-10 manufactured by Konica Minolta Co., Ltd.) was added and immersed. The polypropylene bottle is allowed to stand in an environment at a temperature of 85 ° C. and a humidity of 85% for 300 hours, and then the test solution is collected, and the acetic acid concentration in the solution is measured by high performance liquid column chromatography (manufactured by Shimadzu Corporation) It analyzed by. The results are shown in Table 1.
The ionic compounds used in the above evaluation are as follows. The melting point of the ionic compound was measured by differential scanning calorimetry (DSC) at a temperature rising rate of 10 ° C./min from −20 ° C. to 400 ° C.

  As shown in Table 1, in the ionic compounds (C3) and (C4), the acetic acid concentration in the solution is high, so it is considered that the hydrolysis of the TAC film has proceeded. On the other hand, in the ionic compounds (C1) and (C2), the progress of hydrolysis of the TAC film is considered to be low because the concentration of acetic acid in the solution is low. In particular, in the case of the ionic compound (C1), the concentration of acetic acid in the solution was approximately the same as that of water for reference.

[GPC]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the (meth) acrylic polymer (A) were determined by gel permeation chromatography (GPC method) under the following conditions.
-Measuring device: HLC-8320GPC (made by Tosoh Corp.)
・ GPC column configuration: the following 4 columns (all manufactured by Tosoh Corporation)
(1) TSKgel HxL-H (guard column)
(2) TSKgel GMHxL
(3) TSKgel GMHxL
(4) TSKgel G2500HxL
・ Flow rate: 1.0 mL / min
・ Column temperature: 40 ° C
Sample concentration: 1.5% (w / v) (diluted with tetrahydrofuran)
-Mobile phase solvent: tetrahydrofuran-Standard polystyrene conversion

Synthesis Example A1
90 parts of 2-methoxyethyl acrylate, 6.5 parts of n-butyl acrylate, 3 parts of 2-hydroxyethyl acrylate, 0.5 parts of acrylamide in a reaction apparatus equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube And 100 parts of ethyl acetate solvent were charged, and the temperature was raised to 80 ° C. while introducing nitrogen gas. Next, 0.1 part of 2,2′-azobisisobutyronitrile was added, and a polymerization reaction was performed at 80 ° C. for 6 hours in a nitrogen gas atmosphere. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution having a solid concentration of 30% by mass. Mw of the obtained (meth) acrylic polymer A1 was 1,000,000, and Mw / Mn was 7.5.

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

[Composition example A4]
Into a reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen introducing pipe, 100 parts of a toluene solvent was charged, and the temperature was raised to 90 ° C. while introducing nitrogen gas. Next, 80 parts of 2-methoxyethyl acrylate, 20 parts of n-butyl acrylate and 2 parts of 2,2'-azobisisobutyronitrile are added dropwise over 2 hours from the dropping funnel, and further 2,2'-azobis 1 part of isobutyro nitrile was added, and a polymerization reaction was carried out at 90 ° C. for 6 hours under a nitrogen gas atmosphere. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution with a solid concentration of 30% by mass containing a mixed solvent of toluene and ethyl acetate. Mw of the obtained (meth) acrylic polymer A4-2 was 5,000, and Mw / Mn was 2.1.

  Next, (meth) acrylic polymer A4-2 is contained in 100 parts of a polymer solution having a solid content concentration of 30% by mass containing (meth) acrylic polymer A4-1 obtained in the same manner as in Synthesis Example A1. Ten parts of a polymer solution having a solid concentration of 30% by mass was added to prepare a polymer solution having a solid concentration of 30% by mass.

Synthesis Example A5
The same procedure as in Synthesis Example A1 was conducted, except that the polymerizable monomer used for the polymerization reaction was changed as described in Table 2, and 0.15 part of 2,2'-azobisisobutyronitrile was blended. A polymer solution having a solid content concentration of 30% by mass, which contains the (meth) acrylic polymer A5, was prepared. The results are shown in Table 2.

Synthesis Examples A6 and A7
The procedure was carried out in the same manner as in Synthesis Example A1 except that the polymerizable monomer used for the polymerization reaction was changed as described in Table 2, and the blending amount of ethyl acetate charged with the polymerizable monomer was 200 parts. A polymer solution having a solid content concentration of 25% by mass was prepared, which contains a (meth) acrylic polymer A6 or A7. The results are shown in Table 2.

Example 1
(1) Preparation of adhesive composition The (meth) acrylic polymer solution (solid content concentration: 30% by mass) obtained in Synthesis Example A1 and the crosslinking agent (B) (B1): manufactured by Nippon Polyurethane Industry Co., Ltd. “Coronate L” (solids concentration 75% by mass) and (C1): (nC ₄ H ₉ ) ₃ (CH ₃ ) N ⁺ (CF ₃ SO ₂ ) ₂ N ⁻ as the ionic compound (C) An adhesive composition was obtained by mixing “KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent (D). The ratio of each component is 0.4 parts of (B1) and 2.0 parts of (C1) to 100 parts of the polymer A1 contained in the (meth) acrylic polymer solution obtained in Synthesis Example A1. And (D) an amount of 0.2 parts (all are solid content values).

(2) Preparation of Pressure-Sensitive Adhesive Sheet After foaming, the pressure-sensitive adhesive composition obtained in the above (1) was applied onto a release-treated polyethylene terephthalate film (PET film) using a doctor blade at a liquid temperature of 25 ° C. It dried at 90 degreeC for 3 minutes, and formed the coating film with a dry film thickness of 20 micrometers. On the opposite side of the coated surface of the PET film to which the PET film is attached, a peeling-treated PET film is further attached, allowed to stand for 7 days in a 23 ° C./50% RH environment, and aged to obtain two PET films. A pressure-sensitive adhesive sheet having a 20 μm-thick pressure-sensitive adhesive layer sandwiched therebetween was obtained.

(3) Preparation of Polarizing Plate with Pressure-Sensitive Adhesive Layer After foaming, the pressure-sensitive adhesive composition obtained in the above (1) was applied on a peeling-treated polyethylene terephthalate film (PET film) using a doctor blade and the liquid temperature 25 It applied at ° C and dried at 90 ° C for 3 minutes to obtain a pressure-sensitive adhesive sheet having a dry film thickness of 20 μm. The sheet and a polarizing plate (thickness: 110 μm, layer structure: triacetyl cellulose film / polyvinyl alcohol film / triacetyl cellulose film) are laminated so that the coating film and the polarizing plate are in contact with each other, and 23 ° C./50% The mixture was allowed to stand for 7 days under the conditions of RH for aging to obtain a polarizing plate with a pressure-sensitive adhesive layer having a PET film, a pressure-sensitive adhesive layer with a thickness of 20 μm, and a polarizing plate.

[Examples 2 to 10, Comparative Examples 1 to 3]
A pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and a polarizing plate with a pressure-sensitive adhesive layer were obtained in the same manner as in Example 1 except that the composition was changed as described in Table 3 in Example 1.
In addition, each material of Table 3 is as showing below.

Crosslinking agent (B)
B1: Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L, solid concentration 75% by mass)
B2: A trimethylolpropane adduct of xylylene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., TD-75, solid content concentration 75% by mass)
B3: Epoxy-based crosslinking agent (manufactured by Soken Chemical Co., Ltd., E-5 CM, solid content concentration 5% by mass)
Ionizable compound (C)
The same as the ionic compounds C1 to C4 used in the above [Evaluation of ionic compounds].
Silane coupling agent (D)
D: Glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-403)

[Evaluation]
[Gel fraction]
About 0.1 g of a pressure-sensitive adhesive layer is taken from a pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples in a sampling bottle, and 30 mL of ethyl acetate is added thereto and shaken for 4 hours. The resultant was filtered through a wire mesh, and the residue on the wire mesh was dried at 100 ° C. for 2 hours to determine the dry weight. The gel fraction of the pressure-sensitive adhesive layer was determined by the following equation.
· Gel fraction (%) = (dry weight / adhesive layer collection weight) x 100 (%)

[Surface resistance value]
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 100 mm × 100 mm to prepare test pieces. The PET film was peeled off from the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer was sandwiched between the circular front and back electrodes. A voltage of 100 V was applied, and the surface resistance value after 60 seconds was measured. In addition, the measurement is implemented by the double ring electrode method based on JISK6911 (1995), and the surface resistance value measurement used R8252 digital electrometer (made by ADCC).

[Measurement of adhesive force]
A polarizing plate with a pressure-sensitive adhesive layer (a laminate comprising a PET film / pressure-sensitive adhesive layer / a polarizing plate) obtained in Examples and Comparative Examples was cut into a size of 70 mm × 25 mm to prepare a test piece. The PET film is peeled off from the test piece, and the laminate consisting of the pressure-sensitive adhesive layer / polarizing plate is attached using a laminator roll so that the pressure-sensitive adhesive layer and the alkali glass plate are in contact with one side of the 2 mm thick alkali glass plate. I wore it. The resulting laminate was held in an autoclave adjusted to 50 ° C./5 atm for 20 minutes. Then, after leaving in an environment of 23 ° C./50% RH for 2 hours or more, the end of the polarizing plate is pulled at a peeling angle of 180 ° and a peeling rate of 300 mm / min. The adhesion (peel strength) was measured.

[Durability test]
A polarizing plate with a pressure-sensitive adhesive layer (a laminate comprising a PET film / pressure-sensitive adhesive layer / a polarizing plate) obtained in Examples and Comparative Examples was cut into a size of 150 mm × 250 mm to prepare a test piece. Peel off the PET film from the test piece, and use a laminator roll so that the pressure-sensitive adhesive layer and the alkali-free glass plate are in contact with one side of the alkali-free glass plate with a thickness of 2 mm. Sticked to The obtained laminate was held in an autoclave adjusted to 50 ° C./5 atm for 20 minutes to prepare a test plate. Two similar test plates were made. The test plate was left for 500 hours under the conditions of temperature 85 ° C. (heat resistance) or temperature 85 ° C./humidity 90% RH (moisture and humidity resistance). Appearance defects such as foaming from the pressure-sensitive adhesive layer of the test plate, cracks in the test plate, and peeling of the pressure-sensitive adhesive layer were visually observed and evaluated based on the following criteria.

(Standard)
· AA: appearance defect area 0%
-BB: Appearance defect generation area exceeding 0% and less than 3%-CC: Appearance defect generation area-3% to less than 5%-DD: Appearance defect generation area-5% or more

Claims (6)

(A) A (meth) acrylic polymer obtained by polymerizing a polymerizable monomer containing 41% by mass or more of a (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group;
(B) a crosslinking agent,
(C) An ionic compound wherein the anion is selected from N, N-bis (fluorosulfonyl) imide and N, N-bis (trifluoromethanesulfonyl) imide, the cation is an organic cation, and the melting point is 25 ° C. or higher A pressure-sensitive adhesive composition for a polarizing plate containing   The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, further comprising a silane coupling agent (D). The adhesive composition for polarizing plates of Claim 1 or 2 whose organic cation is a tetraalkyl ammonium cation represented by Formula (c-1) in an ionic compound (C).

[In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group. ]   The adhesive sheet for polarizing plates which has an adhesive layer formed from the adhesive composition for polarizing plates of any one of Claims 1-3.   A polarizing plate with a pressure-sensitive adhesive layer having a polarizing plate and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for polarizing plate according to any one of claims 1 to 3 on at least one surface of the polarizing plate .   A polarizing plate has a polarizer and a protective film disposed on the polarizer, and the polarizer, the protective film, and the pressure-sensitive adhesive composition for polarizing plate according to any one of claims 1 to 3. A laminated body in which the pressure-sensitive adhesive layer and the glass substrate are laminated in this order.