KR101908169B1 - Adhesive composition, adhesive sheet, optical film with adhesive, and optical laminate - Google Patents

Abstract

(I)
(식 중, R₁은 수소 또는 메틸; R₂는 알킬 또는 아랄킬이지만, 기 -O-(C₂H₄O)_n-R₃으로 치환되어도 되고, n은 0 또는 1~4의 정수, R₃은 알킬 또는 아릴)로 나타내는 (메타)아크릴산에스테르 94.8~99.89중량％, (A-2) 수산기를 가지는 (메타)아크릴계 단량체 0.1~5중량％, (A-3) 하기 식(Ⅱ)

(Ⅱ)
(식 중, R₄는 수소 또는 메틸; A는 C_{2 -4}의 2가의 기)로 나타내는 카르복실기 함유 (메타)아크릴산에스테르 0.01~0.2중량％.A crosslinking agent and an organic acid are blended in the acrylic resin as the copolymer (A-1) to (A-3) below to form a pressure-sensitive adhesive composition, which is formed into a sheet to form a pressure-sensitive adhesive sheet. (A-1) a compound represented by the following formula (I)

(I)
(C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4, and R ₃ is hydrogen or methyl, R ₂ is alkyl or aralkyl, R ₃ is alkyl or aryl) to represent a (meth) acrylic acid ester 94.8 ~ 99.89 wt%, (a-2) to (meth) acrylic monomer of 0.1 to 5 wt%, (a-3) having a hydroxyl group in formula (ⅱ)

(II)
(Wherein, R ₄ is hydrogen or methyl; A is a divalent group of C _{2 -4)} 0.01 ~ 0.2% by weight of the carboxyl group-containing (meth) acrylic acid ester represented by the.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, an optical film with an adhesive, and an optical laminate,

The present invention relates to a pressure-sensitive adhesive composition suitable for an optical film, a pressure-sensitive adhesive sheet using the same, and an optical film with a pressure-sensitive adhesive. The optical film to be used in the present invention includes, for example, a polarizing plate and a retardation film. The present invention also relates to an optical laminate in which the optical film with a pressure-sensitive adhesive is laminated on a glass substrate and suitably used for liquid crystal display.

The polarizer is mounted on a liquid crystal display device and widely used. The polarizing plate generally has a transparent protective film laminated on both sides of a polarizing film, and a pressure-sensitive adhesive layer is formed on the surface of at least one of the protective films, and the pressure-sensitive adhesive layer is distributed on the pressure-sensitive adhesive layer. In addition, a retardation film is laminated on a polarizing plate in which a protective film is stuck on both sides of a polarizing film to form an elliptically polarizing plate, and a pressure-sensitive adhesive layer / release film is adhered to the retardation film in this order. Further, the pressure-sensitive adhesive layer / release film is adhered to the surface of the retardation film in this order. In this specification, a polarizing plate, an elliptically polarizing plate, a retardation film, and the like provided with a pressure-sensitive adhesive layer are collectively referred to as an optical film. Prior to bonding to the liquid crystal cell, the optical film provided with these pressure sensitive adhesive layers is cut to a predetermined size, and then the release film is peeled off and bonded to the liquid crystal cell through the exposed pressure sensitive adhesive layer. The optical film provided with such a pressure-sensitive adhesive layer has a problem of workability in that the pressure-sensitive adhesive layer tends to be detached at the time of cutting. Therefore, after the pressure-sensitive adhesive layer is formed, it is generally cured by curing for a sufficient period of time, and is still available for improvement in terms of productivity.

As the pressure sensitive adhesive to be applied to the optical film, an acrylic resin which is produced by copolymerizing a monomer having a polar functional group such as a hydroxyl group or a carboxyl group as a main component and having an acrylate ester as a main component is widely used from the viewpoints of transparency and weather resistance. A crosslinking agent is added to such an acrylic resin to give necessary cohesive force. Herein, the crosslinking agent is a compound having at least two functional groups capable of forming a crosslinking structure in response to polar functional groups constituting the acrylic resin, and specifically includes an isocyanate compound, an epoxy compound, a metal chelate compound, an amine compound Compounds. Among them, an isocyanate compound is widely used as a crosslinking agent.

That is, by blending an isocyanate crosslinking agent having at least two isocyanato groups (-NCO) in the molecule with an acrylic resin having a polar functional group, the functional group in the acrylic resin reacts with the isocyanate group in the crosslinking agent over time, The structure is formed to exhibit the cohesive force and the processability is improved. Thus, if the speed of the crosslinking reaction is increased, the time required for exhibiting sufficient workability can be shortened. As a means for raising the speed of the crosslinking reaction, for example, in Japanese Patent No. 4370888 (Patent Document 1), paragraph 0046 discloses compounding an amine compound as a crosslinking catalyst. In this case, an isocyanate compound It is said that it is appropriate.

Japanese Patent Laid-Open Publication No. 2009-173772 (Patent Document 2) proposes that an acrylic resin having a hydroxyl group is blended with a silane compound having an amino group and an isocyanate crosslinking agent to obtain a pressure-sensitive adhesive composition for an optical member exhibiting good workability . Japanese Patent Laid-Open Publication No. 2009-215528 (Patent Document 3) also discloses that an isocyanate-based crosslinking agent and a silane coupling agent are blended with an acrylic resin having an aromatic ring and a small amount of amino group and having a carboxyl group and / or hydroxyl group, Sensitive adhesive composition for an optical film.

When a compound having an amino group or an acrylic resin having an amino group is used as a component of the pressure-sensitive adhesive composition, the crosslinking reaction of the pressure-sensitive adhesive can be promoted, but the pressure-sensitive adhesive composition having an amino group in the constituent The amino group is reacted with the releasing agent in the peeling film and the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition sticks firmly to the peeling film, so that the peeling film can not be peeled off.

Each of these components constituting the pressure-sensitive adhesive composition is dissolved and dissolved in a solvent to prepare a solution, which is then coated on a suitable substrate and dried to form a pressure-sensitive adhesive sheet. At this time, in order to keep the coating property constant, it is required that the viscosity change of the applied solution is small.

On the other hand, the optical film with a pressure-sensitive adhesive layer is applied to the liquid crystal cell on the pressure-sensitive adhesive layer side to form a liquid crystal panel. However, when the optical film is placed under high temperature or high temperature and high humidity conditions in this state, or heating and cooling are repeated, , There is a possibility that foaming occurs in the pressure-sensitive adhesive layer or peeling or peeling may occur between the optical film and the pressure-sensitive adhesive layer or between the pressure-sensitive adhesive layer and the liquid-crystal cell glass. . Further, when exposed to a high temperature, the distribution of the residual stress acting on the optical film becomes uneven and the stress concentration occurs on the outer peripheral portion of the optical film, resulting in a phenomenon called "white void" , It may cause stains, so it is also required to suppress such white spots and stains. In addition, when the optical film with a pressure-sensitive adhesive is applied to the liquid crystal cell, if the optical film is defective, the optical film is peeled once and then the new film is again stuck again. The so-called reworkability that no adhesive remains and haze is not generated is also required.

Disclosure of the Invention An object of the present invention is to provide a pressure-sensitive adhesive sheet which has a small viscosity change in a solution state and has good applicability, a short curing time required until a pressure-sensitive adhesive layer is formed, Or an optical film with a pressure-sensitive adhesive, and which is excellent in durability and workability, a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition, and an optical film with a pressure-sensitive adhesive, To a glass substrate as a representative example, to provide an optical laminate.

The inventors of the present invention have conducted intensive studies to solve these problems. As a result, they have found that (meth) acrylic acid ester is a main component, and a (meth) acrylic monomer having a hydroxyl group and a carboxyl group , A pressure-sensitive adhesive composition having a small viscosity change in a solution state can be obtained by mixing a predetermined amount of a crosslinking agent and an organic acid in an acrylic resin obtained by copolymerization of a monomer mixture containing a (meth) acrylic acid ester monomer having Further, it has been found that when the pressure-sensitive adhesive composition is formed into a sheet-like shape, a high gel fraction can be obtained with a short curing time, and a pressure-sensitive adhesive sheet excellent in workability can be obtained. It has also been found that an optical film with a pressure-sensitive adhesive excellent in workability, durability, and workability can be obtained by providing this pressure-sensitive adhesive sheet as a pressure-sensitive adhesive layer on the surface of an optical film. The present invention has been completed on the basis of such findings.

That is, the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition comprising 94.8 to 99.89% by weight of (meth) acrylic acid ester (A-1) shown below, 0.1 to 5% by weight of (meth) acrylic monomer (B) 0.01 to 0.2% by weight of a crosslinking agent (B), and 0.01 to 0.2% by weight of a (meth) acrylic acid ester (A- , And 0.03 to 5 parts by weight of an organic acid (C).

(Meth) acrylic acid ester (A-1) is represented by the following formula (I), wherein R ₁ represents a hydrogen atom or a methyl group; R ₂ represents an alkyl group or an aralkyl group having not more than 14 carbon atoms, but the hydrogen atom constituting these groups may be substituted with a group -O- (C ₂ H ₄ O) _n -R ₃ wherein n is 0 or 1 - And R ₃ represents an alkyl group or an aryl group having 12 or less carbon atoms.

(I)

(I)

The carboxyl group-containing (meth) acrylic acid ester (A-3) is represented by the following formula (II), wherein R ₄ represents a hydrogen atom or a methyl group; A represents a divalent organic group having 2 to 4 carbon atoms.

(Ⅱ)

(II)

A suitable example of the carboxyl group-containing (meth) acrylic acid ester (A-3) is 2-carboxyethyl acrylate.

In these pressure-sensitive adhesive compositions, the crosslinking agent (B) preferably contains an isocyanate-based compound. The organic acid (C) is preferably a carboxylic acid represented by the following formula (III), wherein R ₅ represents a hydrogen atom or an alkyl or alkenyl group having 4 or less carbon atoms.

(Ⅲ)

(III)

These pressure-sensitive adhesive compositions may further contain a silane-based compound (D), and a suitable amount thereof is in the range of 0.03 to 2 parts by weight.

The pressure sensitive adhesive sheet of the present invention is formed in a sheet form from any one of the above pressure sensitive adhesive compositions. Since the above pressure-sensitive adhesive composition is usually present in a molten state in a solvent, the pressure-sensitive adhesive composition (solution) is applied on a suitable substrate and the solvent is removed by drying to obtain a pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive sheet can have a ratio of the gel fraction after one day to 0.8 or more after coating the pressure-sensitive adhesive composition onto the sheet, relative to the gel fraction after 8 days after coating the pressure-sensitive adhesive composition onto the sheet. The pressure-sensitive adhesive sheet can have a ratio of gel fraction after 4 days from coating of the pressure-sensitive adhesive composition to the sheet after 8 days from coating the pressure-sensitive adhesive composition in sheet form to 0.97 or more.

These pressure sensitive adhesive sheets are generally preferably formed on a plastic film, and a typical example of the plastic film in that case is a release film subjected to release treatment.

In the optical film with a pressure-sensitive adhesive of the present invention, any one of the above-mentioned pressure-sensitive adhesive sheets is bonded to the optical film. It is advantageous that the optical film contains at least one of a polarizing plate and a retardation film.

In the optical laminate of the present invention, the above-mentioned optical film with a pressure-sensitive adhesive is laminated on a glass substrate on the pressure-sensitive adhesive sheet side.

In the pressure-sensitive adhesive composition of the present invention, since the organic acid (C) is blended in a solution state, the viscosity change hardly occurs and the application property is excellent. Further, this pressure-sensitive adhesive composition comprises, as a main component, an acrylic resin (A) comprising a (meth) acrylic acid ester (A-3) having a carboxyl group at a position spaced a predetermined number of atoms from a main chain site by polymerization, (B) is blended, the crosslinking reaction proceeds rapidly, and the curing time until the gel fraction reaches a predetermined gel fraction after coating the pressure-sensitive adhesive composition into a sheet form can be shortened, thereby improving the workability of the formed pressure-sensitive adhesive sheet .

The optical film with a pressure-sensitive adhesive of the present invention is excellent in workability as described above, and once laminated on a glass substrate, if any defect occurs, the adhesive film remains on the surface of the glass substrate after peeling from the glass substrate together with the adhesive. And haze are less likely to occur, and can be used again as a glass substrate, resulting in excellent workability.

This optical film with a pressure-sensitive adhesive is laminated on, for example, a glass substrate of a liquid crystal cell to provide an optical laminate for liquid crystal display. The adhesive layer absorbs and relaxes the stress caused by the dimensional change of the optical film and the glass substrate in an environment in which the optical laminate is heated under high temperature conditions and under repeated heating and cooling conditions so that local stress concentration And the lifting and peeling of the pressure-sensitive adhesive layer against the glass substrate is suppressed. It is also possible to prevent the concentration of stress when exposed to high temperatures and to suppress the occurrence of white spots and unevenness.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic cross-sectional view showing an example of a suitable layer structure of an optical laminate according to the present invention. FIG.

Hereinafter, the present invention will be described in detail. The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A), a crosslinking agent (B) and an organic acid (C). First, each component constituting the pressure-sensitive adhesive composition will be described.

[Acrylic resin (A)]

The acrylic resin (A) constituting the pressure-sensitive adhesive composition of the present invention contains a structural unit derived from the (meth) acrylic acid ester (A-1) represented by the formula (I) Includes a structural unit derived from a monomer (A-2) and a structural unit derived from a carboxyl group-containing (meth) acrylic ester (A-3) represented by the formula (II). Here, (meth) acrylic acid means either acrylic acid or methacrylic acid, and "(meth)" when other (meth) acrylate is used is the same. In the present specification, the (meth) acrylic acid ester (A-1) represented by the above formula (I) is simply referred to as a "monomer (A-1)" and the (meth) acrylic monomer A-2) "and the carboxyl group-containing (meth) acrylic acid ester (A-3) represented by the above formula (II) are simply referred to as" monomer (A-3) ".

In the formula (I), which is a main structural unit of the acrylic resin (A), R ₁ is a hydrogen atom or a methyl group, and R ₂ is an alkyl group or an aralkyl group having a carbon number of 14 or less. The alkyl group or aralkyl group represented by R ₂ may be substituted with a group -O- (C ₂ H ₄ O) _n -R ₃ in each hydrogen atom. Wherein n represents 0 or an integer of 1 to 4, and R ₃ represents an alkyl group or an aryl group having 12 or less carbon atoms.

Specific examples of the monomer (A-1) in which R ₂ in the formula (I) is an unsubstituted alkyl group include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, The same straight chain alkyl acrylate; Branched acrylic acid alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate and isooctyl acrylate; Linear methacrylic alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate and lauryl methacrylate; And branched methacrylic alkyl esters such as isobutyl methacrylate, 2-ethylhexyl methacrylate and dioctyl methacrylate are exemplified.

Of these, n-butyl acrylate is preferable, and specifically, the content of n-butyl acrylate is 50% by weight or more among the total monomers constituting the acrylic resin (A) and the content of the monomer (A-1) It is preferable to use it satisfactorily.

Specific examples of the monomer (A-1) in which R ₂ in formula (I) is an aralkyl group include benzyl acrylate and benzyl methacrylate.

Next, in the monomer (A-1), the hydrogen atom of the alkyl group or aralkyl group constituting R ₂ in the formula (I) is substituted with the group -O- (C ₂ H ₄ O) _n -R ₃ Explain. In this group -O- (C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4 as defined above, but is preferably 0, 1 or 2 in particular. R ₃ is an alkyl group or an aryl group having 12 or less carbon atoms, as defined above, and may be linear or branched if the alkyl group has 3 or more carbon atoms. Examples of the aryl group constituting R ₃ include, in addition to phenyl and naphthyl, phenylalkyl substituted with a nucleus alkyl group including tolyl, xylyl, ethylphenyl, biphenylyl (or phenylphenyl), and the like. It is particularly preferred that R ₃ is an aryl group.

In the monomer (A-1), R ₂ in the formula (I) is an alkyl group and the hydrogen atom thereof is substituted with a group -O- (C ₂ H ₄ O) _n -R ₃ , Alkoxyalkyl of acrylic acid such as methoxyethyl, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2- (2-phenoxyethoxy) ethyl acrylate and 2- (o-phenylphenoxy) ethyl acrylate, aryloxyalkyl Or aryloxyethoxyalkyl esters; Methoxyethyl methacrylate, ethoxymethyl methacrylate, 2-phenoxyethyl methacrylate, 2- (2-phenoxyethoxy) ethyl methacrylate and 2- (o-phenylphenoxy) methacrylate Alkoxyalkyl, aryloxyalkyl or aryloxyethoxyalkyl esters of methacrylic acid such as ethyl.

These monomers (A-1) may be used alone, or a plurality of different monomers may be used. As described above, it is preferable that the monomer (A-1) is mainly composed of n-butyl acrylate as a main component, but it is also effective to copolymerize other (meth) acrylic acid esters corresponding to the formula (I). As one of the suitable compositions of the monomer (A-1), it is preferable that at least 50 wt% of n-butyl acrylate among all the monomers constituting the acrylic resin (A) (Meth) acrylic acid ester in which R ₂ in the formula is an alkyl group in which the hydrogen atom is replaced by -O- (C ₂ H ₄ O) _n -R ₃ (wherein n and R ₃ are as defined above) By weight based on the total weight of the composition.

The monomer (A-2) is a (meth) acrylic monomer having a hydroxyl group, and examples thereof include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate and 2- (2-hydroxyethoxy) ethyl (meth) acrylate. Of these, it is preferable to use 2-hydroxyethyl acrylate as one of the monomers (A-2) constituting the acrylic resin (A).

The monomer (A-3) is represented by the above formula (II). In this formula (II), R ₄ is a hydrogen atom or a methyl group, and A is a divalent organic group having 2 to 4 carbon atoms. The divalent organic group represented by A is typically alkylene, and it is preferably straight-chain alkylene. However, it is preferred that the carbon chain connecting the (meth) acrylic acid moiety CH ₂ C (R ₄ ) COO- and the terminal carboxyl group -COOH May be branched when the number of carbon atoms is 3 or more on the premise that at least two of them are connected in series. Among the formula (II), an acrylic acid ester is preferable, and specific examples thereof include 2-carboxyethyl acrylate, 3-carboxypropyl acrylate, 4-carboxybutyl acrylate and the like. Of course, the compound in which these acrylic acid esters are changed to methacrylic acid esters can also be a monomer (A-3).

2-carboxyethyl acrylate is usually produced by dimerization of acrylic acid. In this case, it can be obtained as a mixture of acrylic acid itself and an oligomer of acrylic acid or more, in addition to 2-carboxyethyl acrylate as a main component, Many are sold as. Thus, it is of course not necessary to copolymerize other carboxyl group-containing (meth) acrylic monomers with the carboxyl group-containing (meth) acrylic acid ester (A-3) represented by the formula (II).

In the acrylic resin (A) specified in the present invention, the content of the structural unit derived from the (meth) acrylic acid ester represented by the formula (I), that is, the monomer (A-1) is 94.8 to 99.89% by weight, The content of the structural unit derived from the (meth) acrylic monomer (A-2) is 0.1 to 5% by weight, and the content of the structural unit derived from the carboxyl group- containing (meth) acrylic acid ester, The content of the structural unit is 0.01 to 0.2% by weight. By copolymerizing the monomers (A-1), (A-2) and (A-3) at such a limited ratio, a pressure-sensitive adhesive composition can be obtained which gives a pressure-sensitive adhesive sheet excellent in workability. The content of the structural unit derived from the monomer (A-1) is preferably 95% by weight or more, especially 96% by weight or more, and more preferably 99.5% by weight or less. The content of the structural unit derived from the monomer (A-2) is preferably 0.5% by weight or more, more preferably 4% by weight or less, particularly 3% by weight or less. The content of the structural unit derived from the monomer (A-3) is preferably 0.18% by weight or less, particularly 0.15% by weight or less. Of course, the total amount of the structural units derived from each of the monomers (A-1), (A-2) and (A-3) does not exceed 100% by weight.

The acrylic resin (A) used in the present invention may contain a structural unit derived from a monomer other than the above-mentioned monomers (A-1), (A-2) and (A-3). Examples of the monomers other than the monomers (A-1), (A-2) and (A-3) include unsaturated monomers other than the formula (II) having a polar functional group other than the hydroxyl group, Acrylate esters, styrene monomers, vinyl monomers, (meth) acrylamide derivatives, and monomers having a plurality of (meth) acryloyl groups in the molecule.

Unsaturated monomers other than the formula (II) having a polar functional group other than the hydroxyl group will be described. Herein, the polar functional group other than the hydroxyl group may be a free carboxyl group, a heterocyclic group including an epoxy ring, and the like. The oligomer of acrylic acid itself or a trimer or more of acrylic acid described in the monomer (A-3) described above corresponds to an unsaturated monomer other than the formula (II) having a free carboxyl group. Examples of the unsaturated monomer having a heterocyclic group include acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl acrylate Acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, and glycidyl (meth) acrylate.

In the case of copolymerizing an unsaturated monomer having a polar functional group other than a hydroxyl group, the (meth) acrylic monomer (A-2) having a hydroxyl group and the carboxyl group-containing (meth) acrylic acid ester (A-3) Based on the total monomers constituting the acrylic resin (A), the total amount of the unsaturated monomers having a polar functional group is preferably 5% by weight or less, more preferably 4% by weight or less, particularly preferably 3% by weight or less.

Next, (meth) acrylic acid esters having an alicyclic structure in the molecule will be described. The alicyclic structure is a cycloparaffin structure having a carbon number of usually 5 or more, preferably 5 to 7 or so. Specific examples of the acrylic ester having an alicyclic structure include acrylic acid esters such as acrylic acid esters such as cyclohexyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, acrylic acid cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, Cyclohexyl methoxyacrylate, cyclohexyl acrylate, cyclohexyl acrylate, and the like. Specific examples of methacrylic acid esters having an alicyclic structure include methacrylic acid esters such as isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, methacrylic Trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, and cyclohexylphenyl methacrylate.

Examples of the styrene-based monomer include, in addition to styrene, alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene and octylstyrene; Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene and iodostyrene; Also, there are nitrostyrene, acetylstyrene, methoxystyrene, divinylbenzene, and the like.

Examples of vinyl monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate and vinyl laurate; Vinyl halides such as vinyl chloride and vinyl bromide; Vinylidene halides such as vinylidene chloride; Nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone and vinylcarbazole; Conjugated diene monomers such as butadiene, isoprene, and chloroprene; Also, acrylonitrile, methacrylonitrile, and the like are available.

(Meth) acrylamide derivatives such as N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N- (3- hydroxypropyl) (Meth) acrylamide, N- (4-hydroxybutyl) (meth) acrylamide, N- (5-hydroxypentyl) (Meth) acrylamide, N- (ethoxymethyl) (meth) acrylamide, N- (propoxymethyl) (Meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N- (Meth) acrylamide, 2-acryloylamino-2-methyl (meth) acrylate, N- -1-propanesulfonic acid and the like.

Examples of the monomer having a plurality of (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9- (Meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di A monomer having an acryloyl group;

And monomers having three (meth) acryloyl groups in the molecule such as trimethylolpropane tri (meth) acrylate.

When a monomer other than the monomers (A-1), (A-2) and (A-3) which are essential components of the acrylic resin (A) is copolymerized with the monomer having no polar functional group, It is preferable that the content is usually not more than 5% by weight, more preferably not more than 3% by weight, particularly not more than 1% by weight based on the entire monomers constituting the composition.

The resin component constituting the pressure-sensitive adhesive composition is composed of the (meth) acrylic acid ester represented by the formula (I), that is, the monomer (A-1), the (meth) acrylic monomer (A) having a structural unit derived from each of the carboxyl group-containing (meth) acrylic acid ester represented by the general formula (1), that is, the monomer (A-3). The acrylic resin (A) having the structural units derived from the monomers (A-1), (A-2) and (A-3) at a predetermined ratio may be mixed with an acrylic resin different from the acrylic resin. The different acrylic resins to be mixed in this case include, for example, those having a structural unit derived from the (meth) acrylic acid ester of the formula (I) and having no polar functional group. The acrylic resin (A) having a predetermined proportion of the structural units derived from the monomers (A-1), (A-2) and (A-3) is not less than 80% by weight and not less than 90% .

The acrylic resin (A) obtained by copolymerization of the monomer mixture containing the monomers (A-1), (A-2) and (A-3) has a weight average molecular weight in terms of standard polystyrene by gel permeation chromatography (GPC) Mw is in the range of 500,000 to 2,000,000. The weight average molecular weight Mw is particularly preferably from 500,000 to 170,000. If the weight average molecular weight in terms of standard polystyrene is 500,000 or more, the adhesiveness under high temperature and high humidity is improved, and the possibility of peeling or peeling between the glass substrate and the pressure sensitive adhesive sheet tends to be lowered. . If the weight average molecular weight is not more than 2,000,000, even if the size of the optical film adhered to the pressure-sensitive adhesive sheet changes, the pressure-sensitive adhesive layer changes in accordance with the dimensional change thereof. So that there is a tendency that white vignetting and unevenness are suppressed. The molecular weight distribution represented by the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is not particularly limited, but is preferably in the range of about 3 to 7, for example.

It is preferable that the acrylic resin (A) has a glass transition temperature in the range of -10 to -60 占 폚 in order to exhibit adhesiveness. The glass transition temperature of the resin can be measured by a differential scanning calorimeter.

The acrylic resin (A) can be produced by various known methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method and a suspension polymerization method. In the production of the acrylic resin, usually a polymerization initiator is used. The polymerization initiator is used in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the total amount of all the monomers used in the production of the acrylic resin.

As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, and the like are used. As the photopolymerization initiator, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone and the like can be given. As the thermal polymerization initiator, for example, 2,2'-azobisisobutylonitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane- (2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile), dimethyl-2,2 ' Azo compounds such as azobis (2-methylpropionate) and 2,2'-azobis (2-hydroxymethylpropionitrile); Lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate , organic peroxides such as tert-butyl peroxypivalate and (3,5,5-trimethylhexanoyl) peroxide; And inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Redox-based initiators in which a peroxide and a reducing agent are used in combination may also be used as a polymerization initiator.

As a method for producing an acrylic resin, a solution polymerization method is preferable among the above-mentioned methods. A specific example of the solution polymerization method will be described. A desired monomer and an organic solvent are mixed, and a thermal polymerization initiator is added in a nitrogen atmosphere, and the solution polymerization is carried out at about 40 to 90 ° C, preferably about 50 to 80 ° C for 3 to 15 hours Followed by stirring. In order to control the reaction, a monomer or a thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a state dissolved in an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; Esters such as ethyl acetate and butyl acetate; Aliphatic alcohols such as propyl alcohol and isopropyl alcohol; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and the like.

[Crosslinking agent (B)]

The crosslinking agent (B) and the organic acid (C) are added to the acrylic resin (A) as described above to obtain a pressure-sensitive adhesive composition. The crosslinking agent (B) is a compound having at least two functional groups capable of reacting with a hydroxyl group or a carboxyl group as the polar functional group in the acrylic resin (A) and capable of crosslinking the acrylic resin, and specifically, an isocyanate compound, Metal chelate compounds, and aziridine compounds.

The isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule, and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated ) Xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and the like. An adduct in which an isocyanate compound is reacted with a polyol such as glycerol or trimethylolpropane, or an isocyanate compound in the form of a dimer, a trimer or the like can also be a crosslinking agent used in a pressure-sensitive adhesive. Two or more isocyanate compounds may be mixed and used.

The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include bisphenol A type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglyceride N, N, N ', N'-tetraglycidyl-m, N, N'-tetramethyl aniline, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, -Xylene diamine, and the like. Two or more kinds of epoxy compounds may be mixed and used.

Examples of the metal chelate compound include a compound for boiling acetylacetone or ethyl acetoacetate on a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium .

The aziridine compound is a compound having at least two skeletons of a three-membered ring composed of one nitrogen atom and two carbon atoms, which is also called ethyleneimine, in the molecule, and examples thereof include diphenylmethane-4,4'-bis (1-aziridyne (2-methyl aziridine), tris-1-aziridinylphosphine oxide, triethylenediaminephosphine oxide, triethylenemalamine, isophthaloylbis-1- Hexamethylene-1,6-bis (1-aziridinecapamide), trimethylolpropane tris-? -Aziridinylpropionate, tetramethylolmethane tris-? -Aziridinylpropionate and the like .

Of these crosslinking agents, isocyanate compounds, particularly xylylene diisocyanate, tolylene diisocyanate or hexamethylene diisocyanate, or adducts in which these isocyanate compounds are reacted with a polyol such as glycerol or trimethylolpropane, , A trimer or the like, a mixture of these isocyanate compounds, and the like are preferably used.

Particularly suitable isocyanate compounds include tolylene diisocyanate, adducts obtained by reacting tolylene diisocyanate with a polyol, dimers of tolylene diisocyanate, and trimer of tolylene diisocyanate.

The crosslinking agent (B) is blended in a proportion of 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic resin (A). The blending amount of the crosslinking agent (B) is preferably about 0.1 to 3 parts by weight, more preferably about 0.1 to 1 part by weight, based on 100 parts by weight of the acrylic resin (A). When the amount of the crosslinking agent (B) relative to 100 parts by weight of the acrylic resin (A) is 0.01 part by weight or more, particularly 0.1 part by weight or more, the durability of the pressure-sensitive adhesive sheet tends to be improved. , And that the white voids when the optical film with a pressure-sensitive adhesive is applied to a liquid crystal display device are not conspicuous.

[Organic acid (C)]

The organic acid (C) to be incorporated in the pressure-sensitive adhesive composition is preferably a carboxylic acid represented by the above formula (III). It is preferable that the organic acid (C) is volatilized when the pressure-sensitive adhesive composition is coated on a suitable substrate and then dried.

R ₅ in the formula (III) is a hydrogen atom or an alkyl group or an alkenyl group having not more than 4 carbon atoms. Examples of such carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid and vinylacetic acid. Among them, formic acid, acetic acid, acrylic acid or methacrylic acid is preferable from the viewpoint of volatility.

The organic acid (C) is blended in a proportion of 0.03 to 5 parts by weight based on 100 parts by weight of the acrylic resin (A). The blending amount of the organic acid (C) is preferably 0.05 part by weight or more, particularly 0.1 part by weight or more, per 100 parts by weight of the acrylic resin (A). It is preferably 2 parts by weight or less, particularly 1.5 parts by weight or less, based on 100 parts by weight of the acrylic resin (A). When the amount of the organic acid (C) relative to 100 parts by weight of the acrylic resin (A) is 0.03 parts by weight or more, particularly 0.1 parts by weight or more, the viscosity change of the pressure-sensitive adhesive composition in a solution state is reduced, , It is preferable that the organic acid (C) is difficult to remain in the pressure-sensitive adhesive sheet after drying.

[Silane compound (D)]

The pressure-sensitive adhesive composition of the present invention preferably contains a silane-based compound (D) in order to improve the adhesion between the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive optical film and the glass substrate after the pressure- It is preferable to blend the silane compound (D).

Examples of the silane compound (D) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-glycidoxypropyltrimethoxysilane, 3- 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyl tri (methacryloyloxypropyl) silane, 2- Methoxy silane, 3-mercaptopropyl trimethoxy silane, 3-glycidoxypropyl trimethoxy silane, 3-glycidoxypropyl triethoxy silane, 3-glycidoxypropyl dimethoxymethyl silane, 3- Methoxypropyldimethylsilane, and cyanoethylpropyldimethylsilane. Two or more silane compounds (D) may be used.

The silane compound (D) may be a silicone oligomer type. Examples of the silicone oligomer in the form of a (monomer) - (monomer) copolymer include the following.

3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer And mercaptopropyl group-containing copolymers such as 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer;

Mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltri A mercapto methyl group-containing copolymer such as a methoxy silane-tetraethoxy silane copolymer;

3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane copolymer Tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane- 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer and 3-methacryloyloxypropylmethyl di Copolymers containing methacryloyloxypropyl groups such as methoxy silane-tetraethoxy silane copolymers;

3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane- 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer Copolymers containing acryloyloxypropyl groups such as polymers;

Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer Polymer, vinyl methyl dimethoxy silane-tetramethoxy silane copolymer, vinyl methyl dimethoxy silane-tetraethoxy silane copolymer, vinyl methyl diethoxy silane-tetramethoxy silane copolymer and vinyl methyl diethoxy silane-tetraethoxy Vinyl group-containing copolymers such as silane copolymers, and the like.

These silane-based compounds are often liquid. The blending amount of the silane compound (D) in the pressure-sensitive adhesive composition is usually about 0.01 to 10 parts by weight, preferably 0.03 to 2 parts by weight, more preferably 0.03 to 1 part by weight, based on 100 parts by weight of the solid content of the acrylic resin (A) Parts by weight. When the amount of the silane compound relative to 100 parts by weight of the solid content of the acrylic resin (A) is 0.01 parts by weight or more, particularly 0.03 parts by weight or more, adhesion between the pressure-sensitive adhesive sheet and the glass substrate is improved. If the amount is 10 parts by weight or less, particularly 2 parts by weight or less or 1 part by weight or less, the silane compound tends to be inhibited from bleeding out from the pressure-sensitive adhesive sheet.

[Preparation of pressure-sensitive adhesive composition]

Each of the components described above is mixed in a state dissolved in a solvent to form a pressure-sensitive adhesive composition.

Examples of the solvent include aromatic hydrocarbons such as toluene and xylene; Esters such as ethyl acetate and butyl acetate; Aliphatic alcohols such as propyl alcohol and isopropyl alcohol; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and the like. Although this pressure-sensitive adhesive composition shows good performance, it is preferable that the pressure-sensitive adhesive composition does not contain an amino group in order to avoid a strong adhesion when it comes into contact with a specific release film. It is particularly preferable that it does not have a tertiary amino group.

The pressure-sensitive adhesive composition dissolved in the above solvent is applied on a suitable substrate and dried to form a pressure-sensitive adhesive sheet. The substrate used here is generally a plastic film, and a typical example thereof is a release film subjected to release treatment. The release film is a film obtained by subjecting a surface of a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyallylate to a release agent treatment such as silicone treatment .

Since the pressure-sensitive adhesive composition (solution) of the present invention is applied onto a suitable substrate, and then the solvent is dried and removed to form a pressure-sensitive adhesive sheet, the change in viscosity in the solution state is preferably small. The viscosity change can be defined by the following formula using the viscosity η ₂ after 6 hours from the viscosity η ₁ immediately after the preparation of the pressure-sensitive adhesive composition.

Viscosity change (%) = (? _2- ? ₁ ) /? ₁ × 100

The viscosity change defined by this formula is preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less. If the viscosity change of the pressure-sensitive adhesive composition in a solution state is 20% or less, it is preferable because the coating property of the solution is good. Here, the viscosity is a value measured at the number of revolutions of 12 rpm using two spindles using an analog viscometer (LVT) manufactured by Brookfield.

The pressure-sensitive adhesive composition in the solution state may further contain a crosslinking catalyst, an antistatic agent, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler and a resin other than the acrylic resin (A). Some of them are not dissolved in the solvent constituting the pressure-sensitive adhesive composition and are dispersed. However, even if some of the components are dispersed, the discussion of the above viscosity can be applied equally. When a crosslinking catalyst is mixed with the pressure-sensitive adhesive composition in combination with a crosslinking agent, the pressure-sensitive adhesive sheet can be cured for a short period of time. In the resulting optical film with a pressure-sensitive adhesive, peeling or peeling may occur between the optical film and the pressure- It is possible to inhibit foaming from occurring or to improve the workability.

It is also useful to blend an ultraviolet curable compound with the pressure-sensitive adhesive composition to form a pressure-sensitive adhesive sheet, and then curing the pressure-sensitive adhesive sheet by irradiating ultraviolet rays to form a harder pressure-sensitive adhesive layer.

[Adhesive sheet]

As described above, the pressure-sensitive adhesive sheet of the present invention is formed in a sheet form from the pressure-sensitive adhesive composition described above. The ratio of the gel fraction after allowing the pressure-sensitive adhesive sheet to stand at room temperature for one day after coating the pressure-sensitive adhesive composition as a sheet, relative to the gel fraction after 8 days of storage at room temperature after coating it as a sheet, can do. When the ratio is 0.8 or more, it means that the cross-linking reaction proceeds quickly after coating on the sheet, and the curing of the pressure-sensitive adhesive is proceeding the next day. That is, the ratio of the gel fraction is a criterion of the curing rate. The ratio of the gel fraction after allowing to stand at room temperature for 4 days after coating the pressure-sensitive adhesive composition onto the sheet relative to the gel fraction after the application of the pressure-sensitive adhesive composition in sheet form for 8 days at room temperature can be 0.97 or more . When the ratio is 0.97 or more, it means that the hardening of the pressure-sensitive adhesive is almost completed at the point of the fourth day. That is, the ratio of the gel fraction is a standard for the workability of the adhesive sheet. When the ratio of the gel fraction after allowing to stand at room temperature for one day after coating the sheet composition with respect to the gel fraction after the application of the pressure-sensitive adhesive composition in sheet form and leaving it at room temperature for 8 days is 0.8 or more And the ratio of the gel fraction after left to stand at room temperature for 4 days after coating into a sheet form is more preferably 0.97 or more.

Here, the gel fraction is a value measured according to the following (1) to (4).

(1) A metal mesh (its weight is defined as Wm) consisting of a pressure-sensitive adhesive sheet having a size of about 8 cm × about 8 cm and SUS304 having a size of about 10 cm × about 10 cm is bonded.

(2) The assembly obtained in the above (1) is weighed, its weight is made to be Ws, and then folded four times so as to surround the adhesive sheet and fixed with a stapler, and weighed to be Wb.

(3) The mesh stapled in (2) above was placed in a glass container, and 60 ml of ethyl acetate was added thereto to immerse the glass. The glass container was then stored at room temperature for 3 days.

(4) The mesh is taken out from the glass container, dried at 120 DEG C for 24 hours and weighed. The weight is expressed as Wa, and the gel fraction is calculated based on the following equation.

Gel fraction (% by weight) = [{Wa- (Wb-Ws) -Wm} / (Ws-Wm)

As described above, the pressure-sensitive adhesive sheet is cured by taking a certain amount of time after its production and is used in a state in which the crosslinking reaction proceeds to show a certain degree of gel fraction. The gel fraction in the state in which the crosslinking reaction proceeds, that is, in the state where the curing is completed can be adjusted, for example, by the kind of the acrylic resin (A) which is an effective component of the pressure-sensitive adhesive composition for forming it and the amount of the crosslinking agent. Specifically, the amount of the monomer having a polar functional group containing the monomer (A-2) and the monomer (A-3) in the acrylic resin (A) is increased or the amount of the crosslinking agent (B) , The gel fraction becomes high, so that the gel fraction can be adjusted by adjusting these amounts.

[Optical film with pressure-sensitive adhesive]

In the optical film with a pressure-sensitive adhesive of the present invention, a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition as described above is applied to at least one side of the optical film. In the optical laminate with a pressure-sensitive adhesive in the state that the pressure-sensitive adhesive sheet is bonded to the optical film as described above, or in the optical laminate further laminated on the glass substrate, the layer of the pressure-sensitive adhesive sheet is simply referred to as "pressure- do. The optical film used in the pressure-sensitive adhesive optical film is a film having optical properties, and examples thereof include a polarizing plate and a retardation film.

The polarizing plate is an optical film having a function of emitting polarized light to incident light such as natural light. A linearly polarizing plate having a property of absorbing linearly polarized light having a vibration plane in a certain direction and transmitting linearly polarized light having a vibration plane orthogonal thereto and a linearly polarized plate having a vibration plane in a certain direction, A polarizing plate having properties of transmitting linearly polarized light, an elliptically polarizing plate obtained by laminating a polarizing plate and a retardation film to be described later, and the like. As a suitable example of a polarizing plate, particularly a polarizing film (also referred to as a polarizer) which functions as a linear polarizing plate, a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film .

The retardation film is an optical film exhibiting optical anisotropy, and includes, for example, polyvinyl alcohol, polycarbonate, polyester, polyallylate, polyimide, polyolefin, cyclic polyolefin, polystyrene, polysulfone, polyethersulfone, polyvinylidene fluoride A stretched film obtained by stretching a polymer film composed of rid / polymethyl methacrylate, liquid crystal polyester, acetyl cellulose, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride or the like to the extent of 1.01 to 6 times. Among them, a polymer film in which a polycarbonate film or a cyclic polyolefin film is uniaxially or biaxially stretched is preferable. A monoaxial phase difference film, a wide viewing angle phase difference film, a low light modulus phase difference film, and the like.

A film exhibiting optical anisotropy by application and orientation of a liquid crystal compound or a film exhibiting optical anisotropy by application of an inorganic layer compound can also be used as a retardation film. Such a retardation film is referred to as a temperature-compensated retardation film, and a film in which a rod-shaped liquid crystal sold by Shin-Nippon Petroleum Co. under the trade name of "LC film " A slurry-oriented film of a rod-shaped liquid crystal sold under the trade name of "NH film ", a slurry-oriented film of a circular liquid crystal sold under the trade name" WV film " from FUJIFILM Corporation, Quot; VAC film "and a biaxially oriented film sold under the trade name" new VAC film "from Sumitomo Chemical Co., Ltd., and the like.

In addition, a protective film adhered to these optical films can also be used as an optical film. As the protective film, a transparent resin film is used. As the transparent resin, for example, an acetylcellulose resin represented by triacetylcellulose or diacetylcellulose, a methacrylic resin represented by polymethylmethacrylate, a polyester resin, a polyolefin Based resin, a polycarbonate resin, a polyetheretherketone resin, and a polysulfone resin. The resin constituting the protective film may be blended with a UV absorber such as a salicylic ester compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound or a nickel complex salt compound. As the protective film, an acetylcellulose-based resin film such as a triacetylcellulose film is suitably used.

Among the optical films described above, the linear polarizer is often used in a state in which a protective film is attached to one side or both sides of a polarizing film constituting the linear polarizer, for example, a polarizing film made of a polyvinyl alcohol-based resin. The above-mentioned elliptically polarizing plate is obtained by laminating a linearly polarizing plate and a retardation film, but many of the linearly polarizing plates also have a protective film adhered to one or both sides of the polarizing film. When the pressure-sensitive adhesive sheet according to the present invention is applied to such an elliptically polarizing plate, it is usually bonded to the retardation film side.

The optical film with a pressure-sensitive adhesive is preferably applied to the surface of the pressure-sensitive adhesive layer with a releasing film subjected to the releasing treatment as described above, and the surface of the pressure-sensitive adhesive layer is preferably protected until used. The optical film with a pressure-sensitive adhesive provided with the release film can be obtained by, for example, a method of applying the pressure-sensitive adhesive composition described above to the release-treated surface of a release film to form an adhesive sheet and laminating the obtained pressure- A method in which a composition is applied to form a pressure-sensitive adhesive sheet, a release film is applied to the pressure-sensitive adhesive surface to protect the pressure-sensitive adhesive sheet, and an optical film with a pressure-sensitive adhesive is formed.

The thickness of the pressure-sensitive adhesive layer formed on the optical film is not particularly limited, but is usually preferably 30 占 퐉 or less, more preferably 10 占 퐉 or more, and further preferably 15 to 25 占 퐉. If the thickness of the pressure-sensitive adhesive layer is 30 占 퐉 or less, the adhesiveness under high temperature and high humidity is improved, the possibility of peeling or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be lowered, And even if the thickness of the optical film adhered thereto changes, the thickness of the adhesive layer changes following the dimensional change thereof, so that the brightness of the peripheral edge portion of the liquid crystal cell and the brightness of the center portion So that there is a tendency that white appearance and unevenness are suppressed.

When the optical film with a pressure-sensitive adhesive of the present invention is attached to a glass substrate to form an optical laminate and there is any defect and the optical film is peeled off from the glass substrate, the pressure-sensitive adhesive layer is peeled off according to the optical film, It is easy to attach the optical film with the adhesive again to the glass substrate after peeling, since haze and residual adhesive remaining on the surface of the adhesive film hardly occur. That is, the so-called reworkability is excellent.

[Optical laminate]

In the optical film with a pressure-sensitive adhesive of the present invention, the pressure-sensitive adhesive layer side can be laminated on a glass substrate to obtain an optical laminate. In the case of laminating an optical film with an adhesive on a glass substrate to form an optical laminate, for example, the release film may be peeled off from the optical film with an adhesive attached as described above, and the exposed surface of the adhesive layer may be applied to the surface of the glass substrate. Examples of the glass substrate include a glass substrate for a liquid crystal cell, an anti-glare glass, and a glass for sunglasses. Among them, an optical film (upper polarizing plate) with a pressure-sensitive adhesive is laminated on a glass substrate on the front side (viewing side) of a liquid crystal cell and another optical film with a pressure-sensitive adhesive (lower polarizing plate) is laminated on the glass substrate on the back side of the liquid crystal cell Is preferable in that it can be used as a panel (liquid crystal panel) for a liquid crystal display device. Examples of the material of the glass substrate include soda lime glass, low alkali glass, and alkali-free glass. Non-alkali glass is suitably used for the liquid crystal cell.

Examples of several suitable layer constructions for the optical laminate according to the present invention are shown in a schematic cross-sectional view in Fig. 1 (A), a protective film 3 having a surface treatment layer 2 on one side of a polarizing film 1 is adhered on a surface opposite to the surface treatment layer 2 to form a polarizing plate 5). In this example, the polarizing plate 5 is also the optical film 10 referred to in the present invention at the same time. A pressure sensitive adhesive layer 20 is provided on the surface of the polarizing film 1 opposite to the protective film 3 to form an optical film 25 with an adhesive. The surface of the pressure sensitive adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 as a glass substrate to form the optical laminated body 40.

In the example shown in Fig. 1B, the first protective film 3 having the surface treatment layer 2 on one side of the polarizing film 1 is bonded on the side opposite to the surface treatment layer 2, The second protective film 4 is attached to the other surface of the polarizing film 1 to constitute a polarizing plate 5.

In this example as well, the polarizing plate 5 simultaneously serves as the optical film 10 in the present invention. A pressure sensitive adhesive layer 20 is provided on the outside of the second protective film 4 constituting the polarizing plate 5 to constitute an optical film 25 with an adhesive. The surface of the pressure sensitive adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 as a glass substrate to form the optical laminated body 40.

1C, the protective film 3 having the surface treatment layer 2 on one side of the polarizing film 1 is attached on the side opposite to the surface treatment layer 2 to form a polarizing plate 5). On the surface of the polarizing film 1 opposite to the protective film 3, a retardation film 7 is bonded to the surface of the polarizing film 1 through the interlayer adhesive 8 to constitute the optical film 10. A pressure sensitive adhesive layer (20) is provided on the outer side of the retardation film (7) constituting the optical film (10) to constitute an optical film (25) with a pressure sensitive adhesive. The surface of the pressure-sensitive adhesive layer 20 opposite to the optical film 10 is then laminated on the liquid crystal cell 30 as a glass substrate to form the optical laminate 40.

1 (D), the first protective film 3 having the surface treatment layer 2 on one side of the polarizing film 1 is bonded on the side opposite to the surface treatment layer 2, And the second protective film 4 is adhered to the other surface of the polarizing film 1 to constitute the polarizing plate 5. A retardation film 7 is attached to the outside of the second protective film 4 constituting the polarizing plate 5 through the interlayer adhesive 8 to constitute the optical film 10. A pressure sensitive adhesive layer (20) is provided on the outer side of the retardation film (7) constituting the optical film (10) to constitute an optical film (25) with a pressure sensitive adhesive. The surface of the pressure-sensitive adhesive layer 20 opposite to the optical film 10 is then laminated on the liquid crystal cell 30 as a glass substrate to form the optical laminate 40.

In these examples, the first protective film 3 and the second protective film 4 are generally made of a triacetyl cellulose film, but they may also be composed of various transparent resin films mentioned above. The surface treatment layer formed on the surface of the first protective film 3 may be a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or the like. It is also possible to provide a plurality of layers.

When a retardation film 7 is laminated on the polarizing plate 5 as in the examples shown in Figs. 1C and 1D, in the case of a small and medium-sized liquid crystal display device, as a suitable example of the retardation film 7, / 4 wave plate. In this case, it is general that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7, which is a 1/4 wave plate, intersect at almost 45 degrees. However, depending on the characteristics of the liquid crystal cell 30, There is also some deviation from the figure. On the other hand, in the case of a large-sized liquid crystal display device such as a television, a retardation film having various retardation values is used in accordance with the characteristics of the liquid crystal cell 30 for the purpose of compensating the retardation of the liquid crystal cell 30 or compensating the viewing angle. In this case, it is general that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 are arranged to be almost orthogonal or almost parallel. When the retardation film 7 is constituted by a 1/4 wavelength plate, a uniaxial or biaxially stretched film is suitably used. When the retardation film 7 is provided for compensation of the retardation of the liquid crystal cell 30 or for the purpose of viewing angle compensation, in addition to the uniaxial or biaxially oriented film, a film oriented in the thickness direction in addition to the uniaxial or biaxial stretching, A film referred to as an optical compensation film such as a film in which a retardation-developing substance such as liquid crystal is coated on the support film and is oriented and fixed may be used as the retardation film 7.

Similarly, when the polarizing plate 5 and the retardation film 7 are bonded to each other through the interlaminar adhesive 8 as in the examples shown in Figs. 1C and 1D, the interlaminar adhesive 8 is coated with a general acrylic adhesive But it is of course possible to use the pressure-sensitive adhesive sheet defined in the present invention. The polarizing plate 5 and the retardation film 7 are arranged in such a manner that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 are substantially orthogonal or nearly parallel to each other, In the application in which roll-to-roll bonding can be carried out and the re-peeling property between the two is not required, instead of the interlayer pressure-sensitive adhesive 8 shown in Figs. 1C and 1D, It is also possible to use an adhesive which can not be peeled off. Examples of such an adhesive include an aqueous adhesive agent composed of an aqueous solution or an aqueous dispersion and exhibiting an adhesive force by evaporating water as a solvent, and an ultraviolet curable adhesive agent cured by ultraviolet irradiation to develop an adhesive force.

It is also possible to form the pressure-sensitive adhesive layer 20 itself on the retardation film 7 shown in Figs. 1C and 1D by itself and to be an optical film with a pressure-sensitive adhesive according to the present invention . In the optical film with a pressure-sensitive adhesive in which the pressure-sensitive adhesive layer is formed on the retardation film, the pressure-sensitive adhesive layer can be applied to a liquid crystal cell as a glass substrate to form an optical laminate. In addition, a polarizing plate is laminated on the retardation film side You may.

1 shows an example in which the optical film 25 with a pressure-sensitive adhesive is disposed on the viewer side of the liquid crystal cell 30, the optical film with a pressure-sensitive adhesive according to the present invention is arranged on the back side of the liquid crystal cell, It can also be deployed. In the case of disposing the optical film with a pressure-sensitive adhesive of the present invention on the back side of the liquid crystal cell, a protective film having no surface treatment layer is employed in place of the protective film 3 having the surface treatment layer 2 shown in Fig. The rest can be configured in the same manner as (A) to (D) of FIG. In this case, various optical films known to be disposed on the back side of the liquid crystal cell, such as a brightness enhancement film, a light-condensing film, and a diffusion film, may be provided outside the protective film constituting the polarizing plate.

As described above, the optical laminate of the present invention can be suitably used for a liquid crystal display device. The liquid crystal display device formed from the optical laminate of the present invention can be applied to a liquid crystal display for a personal computer including a notebook type, a desktop type, a PDA (Personal Digital Assistant) and the like, a television, a vehicle display, A video camera, an electronic desk calculator, a clock, and the like.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" indicating amounts used or contents are based on weight unless otherwise specified.

In the following examples, the weight average molecular weight was measured by using "Shodex GPC KF-802" (trade name, available from Showa Denko Co., Ltd.), "TSKgel XL" And a total of 5 samples were placed in series and tetrahydrofuran was used as an eluent to prepare a sample having a polystyrene standard conversion of 5 mg / ml, a sample introduction amount of 100 μl, a temperature of 40 ° C and a flow rate of 1 ml / . ≪ / RTI >

First, an acrylic resin (A) to be a main component of the pressure-sensitive adhesive composition according to the present invention and a polymerization example which is similar to the acrylic resin (A) but produces an acrylic resin deviating from the present invention. In the following polymerization examples, the following were used as the carboxyl group-containing monomers.

β-CEA: β-carboxyethyl acrylate sold under the trade name "β-CEA" by Daicel Cytech Co., Ltd. The chemical composition,

CH ₂ = CH (COOCH ₂ CH ₂ ) _n COOH (n = average 1)

Specifically 40% of 2-carboxyethyl acrylate (i.e., a dimer of acrylic acid), 40% of an oligomer of trimeric acrylic acid or more and 20% of acrylic acid. Hereinafter, it is referred to as " beta-CEA " Hereinafter, when it is referred to as " 2-carboxyethyl acrylate ", a dimer of acrylic acid,

CH ₂ = CHCOOCH ₂ CH ₂ COOH

It is assumed to refer to itself.

[Polymerization Example 1]

A reactor equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirrer was charged with 120 parts of ethyl acetate. After replacing air in the apparatus with nitrogen gas, oxygen was not added and the internal temperature was raised to 75 ° C. A total amount of azobisisobutyronitrile (polymerization initiator) (0.05 part) dissolved in 5 parts of ethyl acetate was added in an amount of 69.0 parts, and then 69.9 parts of butyl acrylate as a monomer (A-1) and 20.0 parts of methyl acrylate , 8.0 parts of 2- (2-phenoxyethoxy) ethyl acrylate, 2.0 parts of 2-hydroxyethyl acrylate as the monomer (A-2) and 0.1 parts of β-CEA as the monomer (A-3) Was added dropwise into the reaction system. After that, the internal temperature was kept at 74 to 76 ° C for 5 hours to complete the reaction. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 40% to prepare an ethyl acetate solution of an acrylic resin. The acrylic resin thus obtained had a weight average molecular weight Mw in terms of polystyrene as measured by GPC of 680,000 and an Mw / Mn of 4.9. This is referred to as acrylic resin A.

[Polymerization Example 2]

81.8 parts of ethyl acetate, 69.7 parts of butyl acrylate as monomer (A-1), 20.0 parts of methyl acrylate and 20.0 parts of 2- (2-phenoxyethoxy) ethyl acrylate as a monomer (A-1) were placed in a reaction vessel equipped with a stirrer, a thermometer, , 2.0 parts of 2-hydroxyethyl acrylate as the monomer (A-2) and 0.3 part of beta-CEA as the monomer (A-3) were charged into the flask, Gt; 55 C. < / RTI > Thereafter, a total amount of a solution obtained by dissolving 0.14 part of azobisisobutyronitrile (polymerization initiator) in 10 parts of ethyl acetate was added. Ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts / hour while the internal temperature was maintained at 54 to 56 DEG C for 1 hour after addition of the initiator, and at the time when the concentration of the acrylic resin reached 35% , The addition of ethyl acetate was stopped and the temperature was maintained at this temperature for 12 hours from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20% to prepare an ethyl acetate solution of an acrylic resin. The weight average molecular weight Mw of the obtained acrylic resin in terms of polystyrene by GPC was 153,000 and Mw / Mn was 4.2. This is referred to as acrylic resin B.

[Polymerization Example 3]

Except that the amount of butyl acrylate charged was changed to 68.85 parts, the amount of 2-hydroxyethyl acrylate charged was changed to 3.0 parts, and the amount of β-CEA was changed to 0.15 parts. In the same manner as in Polymerization Example 2, an ethyl acetate solution of acrylic resin It was prepared. The weight average molecular weight Mw of the obtained acrylic resin in terms of polystyrene by GPC was 144,000 and Mw / Mn was 4.6. This is referred to as acrylic resin C.

[Polymerization Example 4]

Except that the amount of butyl acrylate charged was changed to 67.9 parts, the amount of 2-hydroxyethyl acrylate added was changed to 4.0 parts, and the amount of β-CEA was changed to 0.1 parts. In the same manner as in Polymerization Example 2, an ethyl acetate solution of acrylic resin It was prepared. The obtained acrylic resin had a weight average molecular weight Mw of 147,000 and a Mw / Mn of 4.5 as measured by GPC in terms of polystyrene. This is referred to as acrylic resin D.

[Polymerization Example 5]

Except that the charged amount of butyl acrylate was changed to 70.4 parts and the amount of 2-hydroxyethyl acrylate was changed to 1.0 part, and 0.6 parts of acrylic acid was added instead of the addition of < RTI ID = 0.0 & Of ethyl acetate was prepared. The acrylic resin thus obtained had a weight average molecular weight Mw of 660,000 and a Mw / Mn of 5.0 as measured by GPC in terms of polystyrene. This is referred to as acrylic resin X.

The composition of the monomers charged in Polymerization Examples 1 to 5 and the weight average molecular weight and Mw / Mn of the obtained acrylic resin are summarized in Table 1. In addition, in Polymerization Example 1, the amount of β-CEA added was 0.1% based on the sum of the monomers (ie, the acrylic resin obtained) as shown in Table 1, but 2-carboxyethyl acrylate contained in β- , The proportion of the structural unit derived from 2-carboxyethyl acrylate in the acrylic resin is 0.04%. Polymerization examples 2 to 4 also follow this.

(Footnote in Table 1: Meaning of symbols representing monomers)

(A-1)

BA: butyl acrylate

MA: methyl acrylate

PEA2: Acrylic acid 2- (2-phenoxyethoxy) ethyl

(A-2)

2HEA: 2-hydroxyethyl acrylate

(A-3)

β-CEA: a mixture of 40% of 2-carboxyethyl acrylate (dimer of acrylic acid), 40% of oligomers of trimeric acrylate or more and acrylic acid and 20% of acrylic acid

AA: Acrylic acid

Next, examples and comparative examples in which a pressure-sensitive adhesive is prepared using the acrylic resin prepared above and applied to an optical film will be shown. In the following examples, the following were used as the crosslinking agent, the organic acid, and the silane-based compound, respectively. "Colonate L" and "KBM-403" are trade names.

<Cross-linking agent>

Colonate L: Trimethylol propane of tolylene diisocyanate An ethyl acetate solution (solid content concentration 75%) of the duct body was obtained from Japan Polyurethane Co., Ltd.

<Organic acid>

Acrylic acid: CH ₂ = CHCOOH, liquid, obtained from Japan Shokubai Co., Ltd.

&Lt; Silane-based compound &

KBM-403: 3-glycidoxypropyltrimethoxysilane, liquid, available from Shin-Etsu Chemical Co., Ltd.

[Examples 1 to 11 and Comparative Examples 1 to 5]

(a-1) Production of pressure-sensitive adhesive compositions 1 to 5

A 40% ethyl acetate solution of the acrylic resin A obtained in Polymerization Example 1 was used, and the crosslinking agent (colloquin L) and the organic acid (acrylic acid) described above were added to each of the amounts shown in Table 2 and the above- (KBM-403), and ethyl acetate was further added so that the solid concentration became 28% to prepare pressure-sensitive adhesive compositions 1 to 5. The crosslinking agent (Colonate L) is an ethyl acetate solution having a solid concentration of 75% as described above, but the addition amount shown in Table 2 is the solid content.

(a-2) Production of pressure-sensitive adhesive compositions 6 and 7

Pressure-sensitive adhesive compositions 6 and 7 were prepared by conducting operations according to (a-1) except that 20% acetic acid ethyl acetate solution of acrylic resin B obtained in Polymerization Example 2 was used.

(a-3) Production of pressure-sensitive adhesive compositions 8 and 9

Pressure-sensitive adhesive compositions 8 and 9 were prepared by conducting operations according to (a-1) except that 20% acetic acid ethyl acetate solution of acrylic resin C obtained in Polymerization Example 3 was used.

(a-4) Production of pressure-sensitive adhesive compositions 10 and 11

Pressure-sensitive adhesive compositions 10 and 11 were prepared by conducting operations according to (a-1) except that 20% ethyl acetate solution of acrylic resin D obtained in Polymerization Example 4 was used.

(a-5) Production of pressure-sensitive adhesive compositions 12 to 15

(A-1) to (a-4) were carried out except that the organic acid was not mixed to prepare pressure-sensitive adhesive compositions 12 to 15.

(a-6) Production of pressure-sensitive adhesive composition 16

A pressure-sensitive adhesive composition 16 was prepared by using the 40% ethyl acetate solution of the acrylic resin X obtained in Polymerization Example 5 and operating in the same manner as in (a-1) except that the organic acid was not mixed.

(b) Evaluation of viscosity change of pressure-sensitive adhesive composition

The viscosity of each of the pressure-sensitive adhesive compositions prepared in (a-1) to (a-6) was measured immediately after preparation and after 6 hours of preparation by the aforementioned method. The value of the preparation just after the column of "η _1" of Table 2, respectively, represent the value after preparation six hours a column of "η _2" in Table 2, (η ₁ -η ₂₎ / η ₁ × 100 as determined by a The rate of change in viscosity is shown in the column of &quot; viscosity change &quot; in Table 2.

(c) Production of a pressure-sensitive adhesive sheet

Each of the pressure-sensitive adhesive compositions prepared in (a-1) to (a-6) was subjected to a releasing treatment of a polyethylene terephthalate film (trade name: Coated with an applicator so as to have a thickness of 20 mu m after drying, and dried at 100 DEG C for 1 minute to prepare a pressure-sensitive adhesive sheet.

(d) Measurement of gel fraction of the adhesive sheet

The gel fraction was measured for each of the pressure-sensitive adhesive sheets prepared in (c) for 1 day at room temperature, for 4 days, and for 8 days, respectively. The value after leaving for one day is shown in the column of "the first day" in Table 2, the value after leaving for four days in the column of "the fourth day" of table 2, And the ratio of the gel fraction after leaving for one day to the gel fraction after leaving for 8 days is shown in the column of "Day 1 / Day 8" in Table 2 and the ratio of the gel fraction after leaving for 4 days to the gel fraction after leaving for 8 days The ratios are shown in the column of &quot; Day 4 / Day 8 &quot; in Table 2.

(e) Production of Polarizer with Adhesive

On one surface of a polarizing plate having a three-layer structure in which both surfaces of a polarizing film in which iodine is adsorbed and oriented on polyvinyl alcohol are sandwiched by a protective film made of triacetylcellulose, a surface opposite to the separator of the pressure- Adhesive surface) was laminated by a laminator and then cured for 7 days at a temperature of 23 캜 and a relative humidity of 65% to prepare a polarizing plate with a pressure-sensitive adhesive.

(f) Fabrication and evaluation of optical laminate

The separator was peeled off from the polarizer with a pressure-sensitive adhesive prepared in (e), and the pressure-sensitive adhesive side thereof was attached on both sides of a glass substrate for liquid crystal cell [trade name "EAGLE XG", obtained from Corning Incorporated] so as to become cross- did. This optical laminated body was subjected to an heat resistance test in which it was stored for 96 hours under a drying condition at a temperature of 80 캜. Thereafter, the state of expression of white voids when light was incident from one side of the polarizing film was visually observed. The results were classified according to the following criteria and shown in the column of &quot; white void &quot;

&Lt; Expression state of white void &

◎: No white void is seen at all.

○: White void is hardly noticeable.

△: White void is slightly visible.

X: White voids are markedly observed.

The same optical laminate as above was stored for 300 hours at a temperature of 60 DEG C and a relative humidity of 90% when a heat resistance test was conducted for 300 hours at a temperature of 80 DEG C (&quot; heat resistance &quot; (1 hour) in which the temperature was lowered to -30 ° C from the state of heating at 70 ° C, and then the temperature was raised to 70 ° C. (Hereinafter referred to as &quot; inner HS &quot; in Table 2) was subjected to a heat shock test in which the test was repeated 100 times. The optical laminate after the test was visually observed. The results are classified into the following criteria, and are summarized in the column of &quot; durability &quot;

&Lt; Evaluation Criteria of Heat Resistance Test, Humidity Heat Test and Heat Resistance Impact Test &gt;

?: No change in appearance such as peeling, peeling, foaming and the like can be seen at all.

?: Almost no change in external appearance such as peeling, peeling, and foaming.

Δ: Appearance of peeling, peeling, foaming and the like are slightly visible.

X: Appearance changes such as lifting, peeling, foaming and the like are remarkably confirmed.

(g) Evaluation of lithographic properties of optical film with adhesive

Evaluation of reworkability was carried out as follows. First, the polarizer with a pressure-sensitive adhesive prepared in (e) above was cut into test pieces of 25 mm x 150 mm in size. Next, the separator was peeled off from the test piece, and then the glass plate was bonded to the glass substrate for a liquid crystal cell from the pressure-sensitive adhesive layer side using a bonding machine (trade name "Lamy Packer" manufactured by Fuji Plasma Co., Ltd.) at a temperature of 50 ° C and a pressure of 5 kg / cm ² kPa) for 20 minutes. Subsequently, the resultant was heat-treated at 70 ° C for 2 hours and then stored in an oven at 50 ° C for 48 hours. Then, the polarizing plate was peeled off from the adhesion test specimen in an atmosphere at a temperature of 23 ° C and a relative humidity of 50% (In a direction parallel to the glass surface in a state in which the polarizer was peeled away from the polarizer) at the speed of 90 deg. C to observe the state of the surface of the glass plate, and classified according to the following criteria. The results are also shown in the column of &quot; reworkability &quot; in Table 2.

<Evaluation Criteria for Re-workability>

⊚: Haze is not confirmed on the surface of the glass plate at all.

?: Almost no haze was observed on the surface of the glass plate.

?: Haze and the like are confirmed on the surface of the glass plate.

X: Residual adhesive remained on the surface of the glass plate.

(Footnote in Table 2)

The meaning of the reference numerals showing the functional group-containing monomers in the column of &quot; acrylic resin &quot;

2HEA: 2-hydroxyethyl acrylate (hydroxyl group-containing component)

β-CEA: a mixture (carboxyl-containing component) of 40% of 2-carboxyethyl acrylate (dimer of acrylic acid), 40% of oligomer of acrylic acid or more of trimer and acrylic acid,

AA: Acrylic acid

Explanation of column of "viscosity"

η ₁ : Viscosity immediately after preparation of pressure-sensitive adhesive composition

η ₂ : Viscosity after 6 hours from the preparation of the pressure-sensitive adhesive composition

Viscosity change (%) = (? _2- ? ₁ ) /? ₁ × 100

As shown in Tables 1 and 2, a predetermined amount of a crosslinking agent was added to an acrylic resin A in which a predetermined amount of 2-carboxyethyl acrylate corresponding to the formula (II) was copolymerized, and a predetermined amount of organic acid was further blended to obtain a pressure- In Examples 1 to 11, a pressure-sensitive adhesive sheet having a gel fraction ratio on the first day and the fourth day with respect to the gel fraction on the eighth day after coating onto the sheet, while suppressing the viscosity change of the composition. For this reason, it is possible to shorten the curing time from the coating after coating to the sheet-like state until the coating can be carried out without any problem, and the workability is excellent. The pressure-sensitive adhesive sheet of these Examples had almost satisfactory results in heat resistance, heat resistance, and thermal shock resistance.

On the other hand, the acrylic resin had a structural unit derived from 2-carboxyethyl acrylate corresponding to the formula (II), but Comparative Examples 1 to 4 in which no organic acid was added showed a large change in viscosity of the composition, Not full yet. In Comparative Example 5 in which the acrylic resin X having no structural unit derived from 2-carboxyethyl acrylate corresponding to the formula (II) was used, the gel fraction on the first day to the gel fraction after coating on the sheet on the 8th day And the ratio of the gel fraction on the fourth day is lower than 0.97, so that it can not be said that the workability is sufficient.

The pressure-sensitive adhesive composition of the present invention exhibits small change in viscosity with time and exhibits good applicability. Further, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition can shorten the curing time required until the sheet can be processed after the sheet is formed, and is excellent in workability and durability and workability. The optical film provided with the pressure-sensitive adhesive sheet is suitably used for a liquid crystal display device.

One… ... Polarizing film,
2… ... Surface treatment layer,
3 ... ... (First) protective film,
4… ... The second protective film,
5 ... ... Polarizer,
7 ... ... Retardation film,
8… ... Interlayer adhesive,
10 ... ... Optical film,
20 ... ... A pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) bonded to a liquid crystal cell (glass substrate)
25 ... ... An optical film with an adhesive,
30 ... ... Liquid crystal cells (glass substrates),
40 ... ... Optical laminate.

Claims (13)

(A) (A-1)

(I)
(Wherein R ₁ represents a hydrogen atom or a methyl group; R ₂ represents an alkyl group or an aralkyl group having a carbon number of 14 or less, and the hydrogen atom constituting these groups is a group -O- (C ₂ H ₄ O) _n -R ₃ , wherein n represents 0 or an integer of 1 to 4, and R ₃ represents an alkyl group or an aryl group having 12 or less carbon atoms)
, 94.8 to 99.89% by weight of (meth) acrylic acid ester represented by the following formula
(A-2) 0.1 to 5% by weight of a (meth) acrylic monomer having a hydroxyl group and
(A-3) a compound represented by the following formula (II)

(II)
(Wherein R ₄ represents a hydrogen atom or a methyl group; and A represents a divalent organic group having 2 to 4 carbon atoms)
And 0.01 to 0.2% by weight of a carboxyl group-containing (meth) acrylic acid ester represented by the following formula (1): 100 parts by weight of an acrylic resin having a weight average molecular weight of 500,000 to 2,000,000,
(B) 0.01 to 5 parts by weight of a crosslinking agent and
(C) 0.03 to 5 parts by weight of an organic acid. The method according to claim 1,
Wherein the carboxyl group-containing (meth) acrylic acid ester (A-3) is 2-carboxyethyl acrylate. The method according to claim 1,
The pressure-sensitive adhesive composition (B) contains an isocyanate compound. The method according to claim 1,
The organic acid (C) is represented by the following formula (III)

(III)
(Wherein R ₅ represents a hydrogen atom or an alkyl or alkenyl group having 4 or less carbon atoms)
Is a carboxylic acid. The method according to claim 1,
(D) 0.03 to 2 parts by weight of a silane-based compound. A pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition according to any one of claims 1 to 5 in a sheet form. The method of claim 6,
Wherein the ratio of the gel fraction after one day to that after coating the sheet composition with respect to the gel fraction after 8 days after coating the pressure sensitive adhesive composition onto the sheet is 0.8 or more. The method of claim 6,
Wherein the ratio of the gel fraction after 4 days from coating of the sheet composition to the gel fraction after 8 days after coating the pressure sensitive adhesive composition onto the sheet is 0.97 or more. The method of claim 6,
A pressure-sensitive adhesive sheet formed on a plastic film. The method of claim 9,
The plastic film is a release film subjected to releasing treatment. An optical film with a pressure-sensitive adhesive, characterized in that the pressure-sensitive adhesive sheet of claim 6 is bonded to an optical film. The method of claim 11,
Wherein the optical film is selected from a polarizing plate and a retardation film. The optical laminate according to claim 11, wherein the optical film with a pressure-sensitive adhesive is laminated on a glass substrate on the pressure-sensitive adhesive sheet side.

Images