JP2016079237A - Adhesive composition for polarizer, adhesive sheet, polarizer and laminate with adhesive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for polarizer excellent in antistatic performance, capable of forming an adhesive layer with durability under high temperature and high humidity and used for lamination of a polarizer and a glass substrate.SOLUTION: There is provided an adhesive composition for polarizer containing (A) a polymerizable monomer having the content of (meth)acrylic acid ester having a polyoxyalkylene group or an alkoxyalkyl group (a1) or 4 mass% or less and the content of a hydroxyl group-containing monomer (a3) of 3 mass% or less, (B) a crosslinking agent and (C) an ionic compound having an anion selected from N,N-bis(fluorosulfonyl)imide and N,N-bis(trifluoromethanesulfonyl)imide, a cation which is an organic cation and the melting point of 25°C or more and used for lamination of a polarizer and a glass substrate.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition for polarizing plates, 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 in vehicles, outdoor instruments or PC displays, televisions, and the like has been expanded, and 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 (eg, a glass plate), and a polarizing plate is attached to the surface of the substrate via an adhesive layer. Accordingly, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is also required to have durability under high temperature and high humidity heat.

  The pressure-sensitive adhesive layer for polarizing plate is usually stuck on the polarizing plate with a cover film peeled off on one side during the production of the liquid crystal element, and then the cover film is peeled off to expose the pressure-sensitive adhesive layer. And then pasted on the substrate. At that time, static electricity is generated because the insulating properties of the cover film and the polarizing plate are high, which may adversely affect the orientation of the liquid crystal or damage electronic components.

  For this reason, antistatic performance is also required for the pressure-sensitive adhesive for polarizing plates, and a technology for incorporating an ionic compound into the base polymer constituting the pressure-sensitive adhesive as a pressure-sensitive adhesive for polarizing plates having antistatic performance has been reported. Has been.

  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 surface protective sheet for an optical member 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.

JP 2010-66756 A JP 2009-19162 A

  In general, the polarizing plate generally has a protective film for protecting the polarizer. The pressure-sensitive adhesive layer is formed in contact with the protective film. However, according to the study by the present inventors, the polymer component constituting the protective film causes a hydrolysis reaction and corrodes the polarizing plate by the ionic compound contained in the pressure-sensitive adhesive layer in a humid heat environment. It turns out that problems arise in long-term reliability. In addition, due to the further thinning of the member and the widening of the range of use in recent years, it is required that the above-mentioned problem does not occur even under conditions more severe than those of the long-term tests so far.

  An object of the present invention is to be used for bonding a polarizing plate and a glass substrate, which is excellent in antistatic performance and capable of forming an adhesive layer having durability under high temperature and high humidity. An adhesive composition for a polarizing plate, an adhesive sheet having an adhesive layer formed from the composition, a polarizing plate with an adhesive layer having the adhesive layer, and a laminate having the adhesive layer are provided. It is in.

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

The present invention includes, for example, the following [1] to [8].
[1] (A) The content of the (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group is 4% by mass or less, and the content of the hydroxyl group-containing monomer (a3) is 3% by mass. %, A (meth) acrylic polymer obtained by polymerizing a polymerizable monomer,
(B) a crosslinking agent;
(C) an ionic compound in which 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; Containing
A pressure-sensitive adhesive composition for a polarizing plate, which is used for bonding a polarizing plate and a glass substrate.

[2] The pressure-sensitive adhesive composition for a polarizing plate according to [1], wherein the melting point of the ionic compound (C) is 25 ° C. or higher and lower than 50 ° C.
[3] The pressure-sensitive adhesive composition for a polarizing plate according to [1] or [2], wherein in the ionic compound (C), the organic cation is a tetraalkylammonium cation represented by the formula (c-1).

［式（ｃ−１）中、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立に直鎖および分岐状から選ばれるアルキル基である。］
［４］ イオン性化合物（Ｃ）において、有機カチオンが、トリブチルメチルアンモニウムカチオンおよびドデシルトリメチルアンモニウムカチオンから選ばれる、［１］〜［３］のいずれか１項に記載の偏光板用粘着剤組成物。

[In the formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently an alkyl group selected from linear and branched. ]
[4] The pressure-sensitive adhesive composition for a polarizing plate according to any one of [1] to [3], wherein in the ionic compound (C), the organic cation is selected from a tributylmethylammonium cation and a dodecyltrimethylammonium cation. .

[5] The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a polymerizable monomer having a content of (meth) acrylic acid ester (a1) of 0 to 2% by mass. The pressure-sensitive adhesive composition for polarizing plates according to any one of [1] to [4] [6] Formed from the pressure-sensitive adhesive composition for polarizing plates according to any one of [1] to [5]. A pressure-sensitive adhesive sheet for a polarizing plate having a pressure-sensitive adhesive layer.

  [7] Adhesive having a polarizing plate and an adhesive layer formed from the adhesive composition for a polarizing plate according to any one of [1] to [5] on at least one surface of the polarizing plate. A polarizing plate with an agent layer.

  [8] The polarizing plate has a polarizer and a protective film disposed on the polarizer, and the polarizer, the protective film, and the polarizing plate adhesive according to any one of [1] to [5] The laminated body formed by laminating | stacking the adhesive layer formed from the agent composition, and the glass substrate in this order.

  According to the present invention, the antistatic performance is excellent, and an adhesive layer having durability under high temperature and high humidity can be formed, which is used for bonding a polarizing plate and a glass substrate. An adhesive composition for a polarizing plate, an adhesive sheet having an adhesive layer formed from the composition, a polarizing plate with an adhesive layer having the adhesive layer, and a laminate having the adhesive layer are provided. be able to.

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

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

[(Meth) acrylic polymer (A)]
In the (meth) acrylic polymer (A), the content of the (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group is 4% by mass or less, and the hydroxyl group-containing monomer (a3) Is a polymer obtained by polymerizing a polymerizable monomer having a content of 3% by mass or less.

  The polymerizable monomer may not include the (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group, and 0% by mass in 100% by mass of the polymerizable monomer. May be included in the range of 4% by mass or less.

Further, the polymerizable monomer may not contain the hydroxyl group-containing monomer (a3), and is in the range of more than 0% by mass and 3% by mass or less in 100% by mass of the polymerizable monomer. May be included.
The polymerizable monomer preferably contains a (meth) acrylic acid ester (a2) that does not have any of a polyoxyalkylene group, an alkoxyalkyl group, and a crosslinkable group. It is preferable to contain a crosslinkable group-containing monomer (a4) other than a hydroxyl group. The polymerizable monomer can further contain another monomer (a5).

  Here, the said crosslinkable group is a group which can introduce | transduce into the (meth) acrylic-type polymer (A) the crosslinking point which can be bridge | crosslinked with a crosslinking agent (B), and a hydroxyl group, an amino group, carboxyl Group and the like.

  Examples of the polymerizable monomer that forms the (meth) acrylic polymer (A) include the above (a2), and include at least one selected from the above (a3) and (a4). The polymerizable monomer containing said (a1) and (a5) is 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)”. The body (a3) is also referred to as “monomer (a3)”, the crosslinkable group-containing monomer (a4) other than the hydroxyl group is also referred to as “monomer (a4)”, and the other monomer (a5) Also referred to as “monomer (a5)”.

<< 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.

A monomer (a1) is represented by a 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 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. Carbon number of an alkylene group is 1-10 normally, Preferably it is 1-5. Carbon number of an alkyl group is 1-10 normally, Preferably it is 1-4. 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) acrylate and alkoxypolyalkylene glycol mono (meth) acrylate.
Examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl ( Examples include meth) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate.

  Examples of the alkoxypolyalkylene glycol mono (meth) acrylate include methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, ethoxydiethylene glycol mono (meth) acrylate, And methoxytriethylene glycol mono (meth) acrylate.

A monomer (a1) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A), the content of the monomer (a1) is 4% by mass or less, preferably 2% by mass or less, more preferably. Is 1% by mass or less.

When the content of the monomer (a1) is 4% by mass or less, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the (meth) acrylic polymer (A) is aggregated in a high heat environment. Excellent power. Therefore, it can be set as the adhesive layer excellent in heat resistance. If the content of the monomer (a1) is 1% by mass or less, the effect is more remarkable. If the content of the monomer (a1) 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 no polyoxyalkylene group, alkoxyalkyl group or crosslinkable group.

A monomer (a2) is represented by a 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 having no polyoxyalkylene group, alkoxyalkyl group or crosslinkable group.

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

  As the monomer (a2), for example, (meth) acrylic acid alkyl ester, (meth) acrylic acid cycloalkyl ester-containing (meth) acrylic acid ester, (meth) acrylic acid aryl ester, ( Examples include meth) acrylic acid aralkyl esters and (meth) acrylic acid aryloxyalkyl esters.

  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) acrylate Relate, stearyl (meth) acrylate, isostearyl (meth) acrylate.

  Examples of (meth) acrylic acid ester such as (meth) acrylic acid cycloalkyl ester, (meth) acrylic acid ester, (meth) acrylic acid aryl ester and (meth) acrylic acid aralkyl ester include cyclohexyl (meth) acrylate, isobornyl ( And (meth) 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. An oxymethyl (meth) acrylate is mentioned.

A monomer (a2) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A), the content of the monomer (a2) is preferably 70% by mass or more, more preferably 87 to 99. It is 9 mass%, More preferably, it is 90-99.9 mass%.

<< Monomer (a3) >>
The monomer (a3) is a monomer containing a hydroxyl group.
A monomer (a3) is represented by a 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 hydroxyl group. Examples of the organic group having a hydroxyl group include a hydroxyalkyl group having 1 to 12 carbon atoms.

  Examples of the monomer (a3) include hydroxyalkyl (meth) acrylate, and examples thereof include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, Examples thereof include 6-hydroxyhexyl (meth) acrylate and 8-hydroxyoctyl (meth) acrylate.

  Examples of the monomer (a3) include, in addition to the compound represented by the formula (a-3), N-hydroxyalkyl (meth) acrylamide, hydroxyalkyl vinyl ether, and alcohol derivatives having an ethylenic double bond. Specific examples include N-methylol acrylamide, N-hydroxyethyl acrylamide, 2-hydroxyethyl vinyl ether, allyl alcohol, and methallyl alcohol.

A monomer (a3) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A), the content of the monomer (a3) is 3% by mass or less, preferably 0.01 to 3% by mass. .

  If the content of the monomer (a3) is 3% by mass or less, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing the (meth) acrylic polymer (A) has an appropriate stress relaxation property. Have. Therefore, it can be set as the adhesive layer excellent in heat resistance and heat-and-moisture resistance.

<< Monomer (a4) >>
The monomer (a4) is a monomer containing a crosslinkable group other than a hydroxyl group.
By using the monomer (a4) as the polymerizable monomer constituting the (meth) acrylic polymer (A), the crosslinking point that can be crosslinked by the crosslinking agent (B) is used as the (meth) acrylic polymer. (A) can be introduced.
A monomer (a4) is represented by a formula (a-4), for example.
CH ₂ = CR ⁹ -COOR ¹⁰ (a-4)
R ⁹ is a hydrogen atom or a methyl group, and R ¹⁰ is an organic group having a crosslinkable group other than a hydroxyl group. Examples of the crosslinkable group other than the hydroxyl group include an amino group and a carboxyl group.

Examples of the organic group for R ¹⁰ include an N-monoalkyl-substituted aminoalkyl group having 1 to 12 carbon atoms and a carboxyl group-substituted aliphatic group.
Examples of the monomer (a4) include amino group-containing (meth) acrylate and carboxyl group-containing (meth) acrylate.

  Examples of amino group-containing (meth) acrylates include N-monoalkyl-substituted aminoalkyl (meth) acrylates. For example, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meta) ) Acrylate and monoethylaminopropyl (meth) acrylate.

Examples of the carboxyl group-containing (meth) acrylate include β-carboxyethyl (meth) acrylate and 5-carboxypentyl (meth) acrylate.
Examples of the monomer (a4) include an ethylenically unsaturated carboxylic acid and (meth) acrylamides in addition to the compound represented by the formula (a-4). Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid. Examples of (meth) acrylamides include N-methacrylate such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and N-hexyl (meth) acrylamide. Monoalkyl-substituted acrylamides; N, N-dialkyl-substituted acrylamides such as N, N-dimethylacrylamide and N, N-dimethylmethacrylamide.

A monomer (a4) may be used individually by 1 type, and may use 2 or more types.
In 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A), the content of the monomer (a4) is preferably 0 to 10% by mass, more preferably 0.01 to 7%. Mass% is preferred.

  In 100% by mass of the polymerizable monomer forming the (meth) acrylic polymer (A), the total content of the monomer (a3) and the monomer (a4) is durability due to appropriate crosslinking. From the viewpoint of the development of stress relaxation properties, it is preferably more than 0% by mass and 13% by mass or less, more preferably 0.1 to 10% by mass, and still more preferably 0.2 to 5% by mass.

<< Monomer (a5) >>
Examples of the monomer (a5) 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, α-methyl Examples thereof include styrene monomers such as styrene; diene monomers such as butadiene, isoprene and chloroprene; and nitrile monomers such as (meth) acrylonitrile.
A monomer (a5) may be used individually by 1 type, and may use 2 or more types.

<< Production conditions for (meth) acrylic polymer (A) >>
The (meth) acrylic polymer (A) can be produced by, for example, a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, and among these, the solution polymerization method Is preferred. Specifically, a polymerization solvent and a polymerizable monomer are charged into a reaction vessel, a polymerization initiator is added in 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 50 to 90 ° C., preferably 60 to 90 ° C., and is allowed to react for 4 to 20 hours.

Examples of the polymerization initiator include azo initiators and peroxide polymerization initiators.
Examples of the azo initiator include 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-carbohydrate) Nitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′- Azobis (N, N′-dimethyleneisobutylamidine), 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azo (Isobutylamide) dihydrate, 4,4′-azobis (4-cyanopentanoic acid), 2,2′-azobis (2-cyanopropanol), dimethyl-2,2′-azobis (2-methylpropionate) Azo compounds such as 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide].

  Examples of peroxide polymerization initiators include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, and di-i-propyl peroxydicarbonate. , Di-2-ethylhexyl peroxydicarbonate, t-butyl peroxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4- 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.

A polymerization initiator may be used individually by 1 type, and may use 2 or more types.
It is not limited that the polymerization initiator is added a plurality of times during the polymerization.
A polymerization initiator is 0.001-5 mass parts normally with respect to 100 mass parts of polymerizable monomers which form a (meth) acrylic-type polymer (A), Preferably it is the range of 0.005-3 mass parts. Used in quantity. Moreover, you may add suitably a polymerization initiator, a chain transfer agent, a polymerizable monomer, and a polymerization solvent during the said polymerization reaction.

Examples of the polymerization solvent used for 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; cyclopentane, Cycloaliphatic hydrocarbons such as cyclohexane, cycloheptane, cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, diphenyl ether; chloroform, Halogenated hydrocarbons such as carbon tetrachloride, 1,2-dichloroethane, chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate, methyl propionate; acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone Ketones 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.
A polymerization solvent may be used individually by 1 type, and may use 2 or more types.

<< Physical properties and content of (meth) acrylic polymer (A) >>
The (meth) acrylic polymer (A) has a weight average molecular weight (Mw) measured by, for example, a gel permeation chromatography method (GPC method), and is usually at least 400,000 in terms of polystyrene, preferably The polymer (A1) is 450,000 to 2,000,000, more preferably 600,000 to 1,800,000, still more preferably 800,000 to 1,800,000, and particularly preferably more than 1,000,000 to 1.8 million. It is preferable from the point of durability of an adhesive layer that Mw is more than the said lower limit. It is preferable at the point of the applicability | paintability of an adhesive composition as Mw is below the said upper limit.

  The polymer (A1) has a molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) measured by GPC method of usually 2 to 60, preferably 3 to 45, more preferably 3 to 20. is there. It is preferable that Mw / Mn is equal to or more than the lower limit in terms of adhesion to a substrate or a polarizing plate. When Mw / Mn is not more than the above upper limit value, it is excellent in heat resistance and preferable in terms of durability maintenance.

  The (meth) acrylic polymer (A) can be composed only of the polymer (A1). The (meth) acrylic polymer (A) may be a blend of the polymer (A1) and the low molecular weight polymer (A2). Use of the blend is preferable in terms of improving wettability and stress relaxation.

  The content of the low molecular weight polymer (A2) is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 1 to 30 parts by mass with respect to 100 parts by mass of the polymer (A1). Part.

Mw measured by GPC method of a low molecular weight polymer (A2) is a polystyrene conversion value, and is usually 50,000 or less, Preferably it is 1000-50,000, More preferably, it is 2000-20,000.
The glass transition temperature (Tg) of the (meth) acrylic polymer (A) can be measured, for example, by a differential scanning calorimeter. From the monomer units constituting the copolymer and the content ratio thereof, Fox It can be calculated by the following formula. For example, the (meth) acrylic polymer (A) can be synthesized so that the glass transition temperature (Tg) determined by the Fox equation is usually −70 to 10 ° C., preferably −60 to 0 ° C. . As the glass transition temperature of a homopolymer composed of each monomer in the Fox formula, for example, a value described in Polymer Handbook Forth Edition (Wiley-Interscience 1999) can be used.

[Crosslinking agent (B)]
The pressure-sensitive adhesive composition of the present invention contains a crosslinking agent (B). A crosslinking agent (B) is suitably selected by the crosslinkable group which can 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 body (network polymer) can be formed, and an adhesive layer excellent in heat resistance can be obtained.

A crosslinking agent (B) may be used individually by 1 type, and may use 2 or more types.
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, the content of the crosslinking agent (B) is 0.01 to 3 parts by mass when the Mw of the (meth) acrylic polymer (A1) is 800,000 or more, and 400,000 to less than 800,000. 5 to 25 parts by mass.

  When Mw of (A1) is 800,000 or more, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition expresses stress relaxation characteristics and has sufficient heat resistance by blending the crosslinking agent (B) within the above range. Sex can be obtained. Moreover, it is excellent in flexibility and adhesion. When Mw of (A1) is 400,000 or more and less than 800,000, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition by blending the cross-linking agent (B) within the above range is due to the cohesive force of the pressure-sensitive adhesive layer. Sufficient heat resistance can be obtained. Moreover, the sticking of the adhesive layer from the substrate or base material, the punching blade, and adhesion to the surrounding polarizing plate are suppressed, and the workability is excellent.

  As the isocyanate compound, an isocyanate compound having 2 or more isocyanate groups in one molecule is usually used, preferably 2 to 8, and more preferably 3 to 6. When the number of isocyanate groups is within the above range, it is preferable from the viewpoint of the crosslinking reaction efficiency between the (meth) acrylic polymer (A) and the isocyanate compound and the flexibility of the pressure-sensitive adhesive layer.

  Examples of the diisocyanate compound having 2 isocyanate groups in one molecule include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate. Aliphatic diisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, 2,2,4-trimethyl. Examples include aliphatic diisocyanates having 4 to 30 carbon atoms such as -1,6-hexamethylene diisocyanate. As the alicyclic diisocyanate, an alicyclic group having 7 to 30 carbon atoms such as isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, etc. Diisocyanate is mentioned. Examples of the aromatic diisocyanate include aromatic diisocyanates having 8 to 30 carbon atoms such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate.

  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 toluene, 1,3,5-triisocyanate benzene, and 4,4 ', 4 "-triphenylmethane triisocyanate.

  Examples of the isocyanate compound include multimers (for example, dimers or trimers, biurets, and isocyanurates) and derivatives (for example, polyhydric alcohols) of the above isocyanate compounds having 2 or 3 isocyanate groups. Addition reaction product with two or more diisocyanate compounds) and polymer. Examples of the polyhydric alcohol in the derivative include trivalent or higher alcohols such as trimethylolpropane, glycerin and pentaerythritol as low molecular weight polyhydric alcohols; high molecular weight polyhydric alcohols such as polyether polyols, Examples include polyester polyol, acrylic polyol, polybutadiene polyol, and polyisoprene polyol.

  Examples of such isocyanate compounds include diphenylmethane diisocyanate trimer, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate or tolylene diisocyanate biuret or isocyanurate, trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate. Reaction product (for example, a trimolecular adduct of tolylene diisocyanate or xylylene diisocyanate), a reaction product of trimethylolpropane and hexamethylene diisocyanate (for example, a trimolecular adduct of hexamethylene diisocyanate), a polyether polyisocyanate, Polyester polyisocyanate is mentioned.

  Among the isocyanate compounds, the reaction product of trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate (coronate L manufactured by Nippon Polyurethane Industry Co., Ltd., Soken Chemical ( TD-75, etc.), isocyanurate of hexamethylene diisocyanate or tolylene diisocyanate (Asahi Kasei Kogyo Co., Ltd. TSE-100, Nippon Polyurethane Industry Co., Ltd. 2050, etc.) is 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′- Diamine glycidylaminomethyl). Examples of commercially available products include E-5CM manufactured by Soken Chemical Co., Ltd. and E-5XM manufactured by Soken Chemical Co., Ltd.

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

  The polarizing plate to which the pressure-sensitive adhesive layer is attached generally has a protective film for protecting the polarizer, and as the protective film, a cellulose film such as triacetyl cellulose, Examples thereof include polycarbonate films and polyethersulfone films, and cellulose films such as triacetyl cellulose are often used.

  Conventionally known ionic compounds have many ionic compounds that cause hydrolysis reaction with triacetylcellulose, while the ionic compound (C) hardly causes hydrolysis reaction with triacetylcellulose. From this, even if a pressure-sensitive adhesive layer containing the ionic compound (C) is affixed on the protective film, the pressure-sensitive adhesive layer exposed to a moist heat environment is not likely to corrode the protective film. A polarizing plate with an adhesive layer having excellent long-term reliability can be obtained.

Anions contained in the ionic compound (C) are N, N-bis (fluorosulfonyl) imide ((FSO ₂ ) ₂ N ⁻ ) and N, N-bis (trifluoromethanesulfonyl) imide ((CF ₃ SO ₂ )). ₂ N ⁻ ).

  Examples of the organic cation contained in the ionic compound (C) include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a pyrroline cation, a cation having a pyrrole ring, an imidazolium cation, a tetrahydropyrimidinium cation, and a dihydropyrim. Examples include midinium cation, pyrazolium cation, pyrazolinium cation, alkylammonium cation, alkylsulfonium cation, alkylphosphonium cation and derivatives thereof. Examples of the cation having a pyrrole ring include a pyrrole cation, an indole cation, and a carbazole cation. Examples of the derivative include a cation having 1 or 2 or more alkyl groups on the ring constituting the organic cation, and the alkyl group usually has 1 to 12 carbon atoms.

  Among these, an alkylammonium cation is preferable, and a tetraalkylammonium cation represented by the formula (c-1) is particularly preferable.

式（ｃ−１）中、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴はそれぞれ独立に直鎖状または分岐状のアルキル基である。

In formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently a linear or branched alkyl group.

Preferably, R ¹ is an alkyl group having 1 to 18 carbon atoms, and R ^{2 to} R ⁴ are alkyl groups having 1 to 8 carbon atoms. More preferably, R ¹ is an alkyl group having 1 to 14 carbon atoms, R ^{2 to} R ⁴ are alkyl groups having 1 to 6 carbon atoms, and more preferably, because a pressure-sensitive adhesive layer that is superior in moist heat resistance is obtained. , R ¹ is an alkyl group having 1 to 10 carbon atoms, and R ^{2 to} R ⁴ are alkyl groups having 1 to 6 carbon atoms. All of the alkyl groups in R ¹ , R ² , R ³ and R ⁴ are preferably n-alkyl groups. Moreover, it is desirable that the alkyl group has a carbon number within the above range in order to develop appropriate compatibility between the (meth) acrylic polymer (A) and the ionic compound (C). By exhibiting appropriate compatibility, good initial antistatic performance is exhibited, and deterioration of antistatic performance due to bleeding over time and deterioration of adhesion to an adherend are suppressed. Furthermore, it is excellent in moisture and heat resistance.

  Examples of the tetraalkylammonium cation represented by the formula (c-1) include a tetramethylammonium cation, a tetraethylammonium cation, a tetrabutylammonium cation, a tetrahexylammonium cation, a trimethyldecylammonium cation, a triethylmethylammonium cation, and a tributylmethylammonium cation. Cation, tributylethylammonium cation, dodecyltrimethylammonium cation, etc. are mentioned.

  The melting point of the ionic compound (C) is 25 ° C. or higher, preferably 25 ° C. or higher and lower than 60 ° C., more preferably 25 ° C. or higher and lower than 50 ° C., particularly preferably 27 ° C. or higher and lower 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 pressure-sensitive adhesive layer during long-term storage. Can do. The melting point can be measured by differential scanning calorimetry (DSC).

  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. Part or less, preferably 0.1 to 10 parts by weight, more preferably 0.1 to 8 parts by weight.

[Silane coupling agent (D)]
The pressure-sensitive adhesive composition of the present invention preferably contains a silane coupling agent (D) in addition to the compound. 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 the prevention of peeling of the polarizing plate in a high-humidity heat environment.

  Examples of the silane coupling agent (D) include 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, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyl Pyrtriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, Examples include 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.

  Content of the silane coupling agent (D) in the adhesive composition for polarizing plates of this invention is 0-1 mass part normally with respect to 100 mass parts of (meth) acrylic-type polymers (A), Preferably it is 0. 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part 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. As an organic solvent, the polymerization solvent demonstrated in the column of << the manufacturing condition of (meth) acrylic-type polymer (A) >> is mentioned. 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 the present specification, “solid content” refers to all components excluding the organic solvent (E) among the components contained in the pressure-sensitive adhesive composition, and “solid content concentration” refers to the pressure-sensitive adhesive composition 100. The ratio of the said solid content with respect to the mass% is said.

[Additive]
The pressure-sensitive adhesive composition of the present invention is an antioxidant, a light stabilizer, a metal corrosion inhibitor, a tackifier, a plasticizer, a cross-linking accelerator, and a surface active agent as long as the effects of the present invention are not impaired in addition to the above components. One or two or more selected from an agent, a (meth) acrylic polymer other than the above (A), and a reworking agent may be contained.

[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 other components as necessary. It can prepare by mixing by a well-known method. For example, a crosslinking agent (B) and an ionic compound (C) are added to a polymer solution containing the (meth) acrylic polymer (A) obtained when the (meth) acrylic polymer (A) is synthesized. And blending with other components as necessary.
Since the pressure-sensitive adhesive composition is excellent in adhesion to a glass substrate or a polarizing plate and durability under high temperature and high humidity, it can be suitably used for bonding a polarizing plate and a 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, the pressure-sensitive adhesive layer can be obtained by proceeding with the crosslinking reaction in the above-mentioned pressure-sensitive adhesive composition, specifically, 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 applied onto a support and varies depending on the type of solvent, but is usually 50 to 150 ° C., preferably 60 to 100 ° C., usually 1 to 10 minutes, preferably 2 to 7 minutes. Then, the solvent is removed and a coating film is formed. The film thickness of the dried coating film is usually 5 to 75 μm, preferably 10 to 50 μm.

  The pressure-sensitive adhesive layer is preferably formed under the following conditions. After apply | coating the adhesive composition of this invention on a support body and sticking a cover film on the coating film formed on the said conditions, normally 3 days or more, Preferably it is 7-10 days, Usually 5-60 degreeC, It is preferably cured under an environment of 15 to 40 ° C., usually 30 to 70% RH, preferably 40 to 70% RH. When crosslinking is performed under the aging conditions as described above, a crosslinked body (network polymer) can be efficiently formed.

  As a method for applying the pressure-sensitive adhesive composition, a known thickness such as a spin coating method, a knife coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, or a gravure coating method may be used. The method of applying and drying can be used.

  Examples of the support and cover film include polyester films such as polyethylene terephthalate (PET); and plastic films such as 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 has a gel fraction of preferably 20 to 98% by mass, more preferably from the viewpoints of distortion suppression of the polarizing plate, cohesion, adhesion, and removability. Is 30 to 98 mass%, more preferably 35 to 95 mass%.

The surface resistance value of the pressure-sensitive 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 to 1. 0.0 × 10 ¹² Ω / □. The surface resistance value indicates the electric resistance on the surface of the pressure-sensitive adhesive layer, and the smaller the value, the smaller the electric 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 structure, it is excellent even under a moist heat acceleration condition of 85 ° C./90% RH, which is stricter than 60 ° C./90% RH. Shows durability.

[Plastic adhesive sheet]
The pressure-sensitive adhesive sheet for polarizing plates of the present invention has a pressure-sensitive adhesive layer formed from the above-mentioned pressure-sensitive adhesive composition for polarizing plates. Examples of the pressure-sensitive adhesive sheet include a double-sided pressure-sensitive adhesive sheet having only the pressure-sensitive adhesive layer, a base material, and a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer formed on both surfaces of the base material, the base material, and one of the base materials. Examples thereof include a single-sided pressure-sensitive adhesive sheet having the above-mentioned pressure-sensitive adhesive layer formed on the surface, and a pressure-sensitive adhesive sheet having a peel-treated cover film attached to the surface of the pressure-sensitive adhesive sheet that is not in contact with the base material.

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

The conditions for forming the pressure-sensitive adhesive layer and the gel fraction are the same as the conditions described in the column [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 adhesive 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 adhesive layer and laminate]
The polarizing plate with an adhesive layer of this invention has a polarizing plate and the adhesive layer formed from the adhesive composition for polarizing plates of this invention in the at least one surface of the said polarizing plate. In this specification, “polarizing plate” is used to include “polarizing film”.

A conventionally well-known polarizing plate can be used as a polarizing plate, 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 resins contain a polarizing component, and extending | stretching is mentioned, for example. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, and a saponified product of an ethylene / vinyl acetate copolymer. Examples of the polarization component include iodine or a dichroic dye.

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

The thickness of the polarizing plate is usually 30 to 250 μm, preferably 50 to 200 μm.
The method for forming the pressure-sensitive adhesive layer on the surface of the polarizing plate is not particularly limited. The method for applying the pressure-sensitive adhesive composition directly on the surface of the polarizing plate using a bar coater and drying and aging, the pressure-sensitive adhesive sheet for polarizing plate of the present invention There is a method in which the pressure-sensitive adhesive layer possessed by is transferred and aged on the surface of the polarizing plate. The conditions for drying and aging, the gel fraction, and the like are the same as the conditions described in the [Adhesive layer] column.

  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 terms of dry film thickness. In addition, the adhesive layer should just be formed in at least one surface of a polarizing plate, the aspect in which an adhesive layer is formed only in the single side | surface of a polarizing plate, the aspect in which an adhesive layer is formed in both surfaces of a polarizing plate Is mentioned.

Moreover, the layer which has other functions, such as a glare-proof layer, a phase difference layer, a viewing angle improvement layer, may be laminated | stacked on the said polarizing plate, for example.
A liquid crystal element is produced by providing the polarizing plate with the pressure-sensitive adhesive layer of the present invention obtained as described above on the substrate surface of the 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, the pressure-sensitive adhesive layer formed from the polarizer, the protective film, the pressure-sensitive adhesive composition for polarizing plate of the present invention, and A laminated body in which glass substrates are laminated in this order can be manufactured.

  As a board | 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, and more preferably 0.05 to 2 mm.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. In the following description of Examples and the like, “part” means “part by mass” unless otherwise specified.

[Evaluation of ionic compounds]
2 g of water and 2 g of ionic compound were added to a polypropylene bottle to prepare a test solution having a concentration of 50% by mass. To this test solution, 0.25 g (thickness 40 μm, 40 mm × 120 mm) of triacetylcellulose film (TAC film; K-10 manufactured by Konica Minolta Co., Ltd.) was added and immersed. The polypropylene bottle was allowed to stand in an environment of 85 ° C. and 85% humidity for 300 hours, and then the test solution was collected and the acetic acid concentration in the solution was measured by high performance liquid column chromatography (manufactured by Shimadzu Corporation). ). The results are shown in Table 1.
The ionic compounds used in the above evaluation are as follows.

  As shown in Table 1, in the ionic compounds (C3) and (C4), the hydrolysis of the TAC film is considered to have progressed because the acetic acid concentration in the liquid was high. On the other hand, in the ionic compounds (C1) and (C2), since the acetic acid concentration in the liquid is low, the progress of hydrolysis of the TAC film is considered to be low. In particular, in the ionic compound (C1), the concentration of acetic acid in the liquid was almost the same as that of reference water.

[GPC]
About the (meth) acrylic-type polymer (A), the weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated | required on condition of the following by the gel permeation chromatography method (GPC method).
-Measuring device: HLC-8320GPC (manufactured by Tosoh Corporation)
-GPC column configuration: The following four 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]
A reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen inlet tube was charged with 94 parts of n-butyl acrylate, 6 parts of acrylic acid, and 250 parts of ethyl acetate solvent, and the temperature was raised to 80 ° C. while introducing nitrogen gas. The temperature rose. 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, it was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 28.5% by mass. Mw of obtained (meth) acrylic-type polymer A1 was 1.8 million, and Mw / Mn was 5.9.

[Synthesis Examples A2, A3, A7 and A8]
Solid content including (meth) acrylic polymer A2, A3, A7 or A8, which is performed in the same manner as in Synthesis Example A1 except that the polymerizable monomer used in the polymerization reaction is changed as described in Table 2. A polymer solution having a concentration of 28.5% by mass was prepared. The results are shown in Table 2.

[Synthesis Example A4]
The polymerizable monomer used in the polymerization reaction was changed as described in Table 2, and the same procedure as in Synthesis Example A1 was conducted except that 0.08 part of 2,2′-azobisisobutyronitrile was blended. A polymer solution containing (meth) acrylic polymer A4 and having a solid concentration of 28.5% by mass was prepared. The results are shown in Table 2.

[Synthesis Example A5]
A reaction apparatus equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen introduction tube was charged with 100 parts of toluene solvent, and the temperature was raised to 90 ° C. while introducing nitrogen gas. Next, 30 parts of n-butyl acrylate, 50 parts of t-butyl acrylate, 20 parts of benzyl acrylate, and 2 parts of 2,2′-azobisisobutyronitrile were dropped from the dropping funnel over 2 hours. 1 part of 2′-azobisisobutyronitrile was added, and a polymerization reaction was performed at 90 ° C. for 6 hours in a nitrogen gas atmosphere. After completion of the reaction, the reaction mixture was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 30% by mass containing a mixed solvent of toluene and ethyl acetate. Mw of obtained (meth) acrylic-type polymer A5-2 was 5,000, and Mw / Mn was 2.1.

  Next, a (meth) acrylic polymer A5-1 was obtained in the same manner as in Synthesis Example A1 except that the polymerizable monomer used in the polymerization reaction was changed as described in Table 2. In 100 parts of the polymer solution having a solid content concentration of 28.5% by mass containing the (meth) acrylic polymer A5-1 obtained, the solid content concentration of 28.5% by mass containing the (meth) acrylic polymer A5-2. 10 parts of the above polymer solution was added to prepare a polymer solution having a solid content concentration of 28.5% by mass.

[Synthesis Example A6]
The polymerization monomer used in the polymerization reaction was changed as described in Table 2, and the same procedure as in Synthesis Example A1 was conducted except that the amount of ethyl acetate charged together with the polymerization monomer was changed to 200 parts. A polymer solution containing a (meth) acrylic polymer A6 and having a solid content concentration of 33% by mass was prepared. The results are shown in Table 2.

[Example 1]
(1) Preparation of pressure-sensitive adhesive composition The (meth) acrylic polymer solution (solid content concentration 28.5% by mass) obtained in Synthesis Example A1 and the crosslinking agent (B) (B1): Nippon Polyurethane Industry Co., Ltd. ) “Coronate L” (solid content concentration 75% by mass), (B3): “E-5CM” (solid content concentration 5% by mass) manufactured by Soken Chemical Co., Ltd., and (C1) as the ionic compound (C) ): (N-C ₄ H ₉ ) ₃ (CH ₃ ) N ⁺ (CF ₃ SO ₂ ) ₂ N ⁻ and “KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent (D) It mixed and the adhesive composition was obtained. The ratio of each component is as follows: (B1) 0.6 part, (B3) 0.01 part with respect to 100 parts of the polymer A1 contained in the (meth) acrylic polymer solution obtained in Synthesis Example A1. , (C1) 2.0 parts and (D) 0.2 parts (both solid content values).

(2) Preparation of pressure-sensitive adhesive sheet After removing bubbles, the pressure-sensitive adhesive composition obtained in (1) above was applied on a polyethylene terephthalate film (PET film) that had been peeled off at a liquid temperature of 25 ° C. using a doctor blade. The film was dried at 90 ° C. for 3 minutes to form a coating film having a dry film thickness of 20 μm. Two PET films were obtained by further laminating the peeled PET film on the surface of the coating film opposite to the surface on which the PET film was applied, and leaving it to stand for aging in a 23 ° C./50% RH environment for 7 days. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 20 μm sandwiched between the layers was obtained.

(3) Preparation of polarizing plate with pressure-sensitive adhesive After removing the bubbles, the pressure-sensitive adhesive composition obtained in (1) above is peeled off onto a polyethylene terephthalate film (PET film) that has been subjected to a release treatment using a doctor blade at a liquid temperature of 25 ° C. And dried at 90 ° C. for 3 minutes to obtain a pressure-sensitive adhesive sheet having a coating film having a dry film thickness of 20 μm. The sheet and the polarizing plate (thickness: 110 μm, layer structure: triacetyl cellulose film / polyvinyl alcohol film / triacetyl cellulose film) were bonded together so that the coating film and the polarizing plate were in contact with each other, and 23 ° C./50%. The plate was allowed to stand and matured for 7 days under the conditions of RH to obtain a polarizing plate with a pressure-sensitive adhesive layer having a PET film, a pressure-sensitive adhesive layer having a thickness of 20 μm, and a polarizing plate.

[Examples 2 to 10, Comparative Examples 1 to 4]
In Example 1, the adhesive composition, the adhesive sheet, and the polarizing plate with an adhesive layer were obtained like Example 1 except having changed the compounding composition as described in Table 3.
In addition, each material of Table 3 is as showing below.

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

[Evaluation]
[Gel fraction]
About 0.1 g of the pressure-sensitive adhesive layer was collected in a sampling bottle from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and 30 mL of ethyl acetate was added and shaken for 4 hours. The mixture was filtered through a metal mesh, the residue on the metal mesh was dried at 100 ° C. for 2 hours, and the dry weight was measured. The gel fraction of the pressure-sensitive adhesive layer was determined by the following formula.
Gel fraction (%) = (Dry weight / Adhesive layer sampling weight) × 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 from the adhesive sheet, and the adhesive layer was sandwiched between 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 was implemented by the double ring electrode method based on JISK6911 (1995), and the surface resistance value measurement used R8252 digital electrometer (made by ADC Co., Ltd.).

[Measurement of adhesive strength]
A polarizing plate with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples (a laminate comprising PET film / pressure-sensitive adhesive layer / polarizing plate) 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 composed of the pressure-sensitive adhesive layer / polarizing plate is pasted on one side of the 2 mm-thick alkali glass plate using a laminator roll so that the pressure-sensitive adhesive layer and the alkali glass plate are in contact with each other. I wore it. The obtained laminate was held in an autoclave adjusted to 50 ° C./5 atm for 20 minutes. Next, after being left in a 23 ° C./50% RH environment for 2 hours or more, the edge of the polarizing plate was pulled at a peeling angle of 180 ° and a peeling speed of 300 mm / min with respect to the alkali glass plate surface of the adherend. The adhesive strength (peel strength) was measured.

[Durability test]
A polarizing plate with a pressure-sensitive adhesive layer obtained in Examples and Comparative Examples (a laminate comprising PET film / pressure-sensitive adhesive layer / polarizing plate) was cut into a size of 150 mm × 250 mm to prepare a test piece. The PET film is peeled off from the test piece, and the pressure-sensitive adhesive layer and the non-alkali glass plate are brought into contact with one side of the 2 mm-thick non-alkali glass plate using a laminator roll. Stuck on. 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 prepared. The test plate was allowed to stand for 500 hours under conditions of a temperature of 85 ° C. (heat resistance) or a temperature of 85 ° C./90% humidity (humidity heat 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 according to the following criteria.

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

Claims (8)

(A) The content of the (meth) acrylic acid ester (a1) having a polyoxyalkylene group or an alkoxyalkyl group is 4% by mass or less, and the content of the hydroxyl group-containing monomer (a3) is 3% by mass or less. A (meth) acrylic polymer obtained by polymerizing a polymerizable monomer;
(B) a crosslinking agent;
(C) an ionic compound in which 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 polarizing plates, which is used for bonding a polarizing plate and a glass substrate.   The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, wherein the melting point of the ionic compound (C) is 25 ° C or higher and lower than 50 ° C. The adhesive composition for polarizing plates of Claim 1 or 2 whose organic cation is a tetraalkylammonium cation represented by Formula (c-1) in an ionic compound (C).

[In the formula (c-1), R ¹ , R ² , R ³ and R ⁴ are each independently a linear or branched alkyl group. ]   The adhesive composition for polarizing plates according to any one of claims 1 to 3, wherein in the ionic compound (C), the organic cation is selected from a tributylmethylammonium cation and a dodecyltrimethylammonium cation.   The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a polymerizable monomer having a (meth) acrylic acid ester (a1) content of 2% by mass or less. The adhesive composition for polarizing plates of any one of -4.   The adhesive sheet for polarizing plates which has an adhesive layer formed from the adhesive composition for polarizing plates of any one of Claims 1-5.   The polarizing plate with an adhesive layer which has a polarizing plate and the adhesive layer formed from the adhesive composition for polarizing plates of any one of Claims 1-5 in the at least one surface of the said polarizing plate. .   A polarizing plate has a polarizer and a protective film disposed on the polarizer, and is formed from the polarizer, the protective film, and the pressure-sensitive adhesive composition for a polarizing plate according to claim 1. A laminate in which the pressure-sensitive adhesive layer and the glass substrate are laminated in this order.