KR101887693B1 - Pressure sensitive adhesive sheet, optical film with pressure sensitive adhesive and optical laminate - Google Patents

Abstract

A pressure-sensitive adhesive composition comprising 100 parts by weight of an acrylic resin having a weight average molecular weight of 1 million to 2,000,000 and 0.01 to 5 parts by weight of a crosslinking agent as a copolymer obtained from a monomer mixture containing (A-1) to (A-3) And is formed into a sheet to form a pressure-sensitive adhesive sheet.
(I) wherein R ₁ is hydrogen or methyl, R ₂ is alkyl or aralkyl, or may be substituted with a group -O- (C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4, and R ₃ is alkyl or aryl), (A-2) 0.1 to 5% by weight of a (meth) acrylic monomer having a hydroxyl group, (a-3) the formula (II) (wherein, R ₄ is hydrogen or methyl; a is a divalent group of C _{2 -4)} a carboxyl group-containing (meth) acrylic ester represented by the 0.01~0.2 wt.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive sheet, an optical film with an adhesive, and an optical laminate,

The present invention relates to a pressure-sensitive adhesive sheet and an optical film with a pressure-sensitive adhesive using the same.

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 to which an optical film with a pressure-sensitive adhesive is applied and which is suitably used for liquid crystal displays.

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, a pressure-sensitive adhesive layer is formed on the surface of at least one protective film, and a release film is adhered on the pressure-sensitive adhesive layer.

There is also a case where a retardation film is laminated on a polarizing plate in which a protective film is bonded to both surfaces of a polarizing film to form an elliptically polarizing plate and the pressure-sensitive adhesive layer / release film is adhered to the retardation film in this order. Further, the pressure-sensitive adhesive layer / release film may be adhered to the surface of the retardation film in this order. In the present specification, a polarizing plate, an elliptically polarizing plate, a retardation film, and the like on which the pressure-sensitive adhesive layer is provided 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, then the release film is peeled off and bonded to the liquid crystal cell via 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 fall off at the time of cutting. Therefore, curing (curing refers to increasing the gel fraction by progressing the crosslinking reaction for a certain period of time after formation of the pressure-sensitive adhesive layer) over a sufficient time after forming the pressure-sensitive adhesive layer, It is general, and there is still room for improvement in terms of productivity.

From the viewpoints of transparency and weatherability, acrylic resins produced by copolymerizing a monomer having a polar functional group such as a hydroxyl group or a carboxyl group as main components are widely used as an adhesive for an optical film. A crosslinking agent is added to such an acrylic resin to provide necessary cohesive force. Herein, the crosslinking agent is a compound having at least two functional groups capable of forming a crosslinking structure in the molecule in response to the polar functional group constituting the acrylic resin, and specific examples thereof include isocyanate compounds, epoxy compounds, metal chelate compounds, Based compounds. Among them, an isocyanate compound is widely used as a crosslinking agent.

That is, by blending an isocyanate-based crosslinking agent having at least two isocyanato groups (-NCO) in a molecule with an acrylic resin having a polar functional group, the functional group in the acrylic resin reacts with the isocyanato group in the crosslinking agent over time A crosslinked structure is formed, and cohesive force is exhibited and workability is improved. Thus, if the speed of the crosslinking reaction is increased, the time required for exhibiting sufficient workability can be shortened. JP2004-190012-A discloses that, as means for increasing the rate of the crosslinking reaction, an amine compound is compounded as a crosslinking catalyst. In this case, it is said that an isocyanate compound is suitable as a crosslinking agent.

In addition, 2009-173772-A proposes that an acrylic resin having a hydroxyl group is mixed with a silane compound having an amino group and an isocyanate-based crosslinking agent to obtain a pressure-sensitive adhesive composition for an optical member exhibiting good processability. Further, in JP2009-215528-A, 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, It is proposed to use a composition of the present invention.

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 as described above, the pressure-sensitive adhesive composition having an amino group in the constituent component can be easily removed There is a problem that the releasing agent in the peeling film reacts with the amino group and sticks firmly to the peeling film, so that the peeling film can not be peeled off.

On the other hand, the optical film with a pressure-sensitive adhesive adheres to the liquid crystal cell on the pressure-sensitive adhesive layer side to form a liquid crystal panel. However, when the liquid crystal panel is placed under high temperature or high temperature and high humidity conditions in this state, , There is a case where foaming occurs in the pressure-sensitive adhesive layer, or floating 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, , And excellent durability. In addition, when exposed to a high temperature, the distribution of the residual stress acting on the optical film becomes uneven, and stress concentration occurs in the outer peripheral portion of the optical film. As a result, a phenomenon in which the outer peripheral portion becomes white during black display, It is necessary to suppress the opacity and the color unevenness because there are cases in which a phenomenon called out or color unevenness is generated in some cases. Further, when the optical film with a pressure-sensitive adhesive is bonded 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. However, A so-called reworkability is required in which no adhesive remains on the cell glass and no clouding occurs.

An object of the present invention is to provide a pressure-sensitive adhesive sheet and pressure-sensitive adhesive sheet which are excellent in durability and reworkability, have a short curing time required until a pressure-sensitive adhesive layer is formed, To provide an adhesive optical film and to bond the optical film with a pressure-sensitive adhesive to a glass substrate having a liquid crystal cell as a typical example, thereby providing an optical laminate. The inventors of the present invention have conducted intensive studies in order 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 is contained at a position apart from the When a pressure-sensitive adhesive composition comprising a crosslinking agent in an acrylic resin obtained by copolymerization of a monomer mixture containing a (meth) acrylic acid ester monomer having a carboxyl group is formed in a sheet form, a high gel fraction is exhibited at a short curing time, Thereby obtaining a pressure-sensitive adhesive sheet. It has also been found that an optical film with a pressure-sensitive adhesive excellent in durability, reworkability and workability can be obtained by providing the pressure-sensitive adhesive sheet as a pressure-sensitive adhesive layer on the surface of the optical film.

That is, the present invention includes the following.

[1] A thermosetting resin composition which comprises 94.8 to 99.89 wt% of a (meth) acrylic acid ester (A-1) represented by the following formula (I), 0.1 to 5 wt% of a (meth) acrylic monomer 0.004 to 0.2% by weight of a carboxyl group-containing (meth) acrylic acid ester (A-3) represented by the following formula (II): 100 parts by weight of an acrylic resin (A) having a weight average molecular weight of 1,000,000 to 2,000,000 , And a crosslinking agent (B) in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the pressure-sensitive adhesive composition.

(Wherein R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group having a carbon number of 14 or less or an aralkyl group having a carbon number of 14 or less, and the hydrogen atom constituting R ₂ is a group -O- (C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4, and R ₃ is an alkyl group having 12 or less carbon atoms or an aryl group having 12 or less carbon atoms.

(Wherein R ₄ represents a hydrogen atom or a methyl group, and A represents a divalent organic group having 2 to 4 carbon atoms.)

[2] The pressure-sensitive adhesive sheet according to [1], wherein the ratio of the gel fraction after two days from the application of the pressure-sensitive adhesive composition in a sheet form to the gel fraction after 7 days from application to the sheet form is 0.8 or more.

[3] The pressure-sensitive adhesive sheet according to [1] or [2], wherein the carboxyl group-containing (meth) acrylic acid ester (A-3) is 2-carboxyethyl acrylate.

[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the crosslinking agent (B) contains an isocyanate compound.

[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the pressure-sensitive adhesive composition further contains 0.03 to 2 parts by weight of the silane compound (C).

[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5], which is formed on a plastic film.

[7] The pressure-sensitive adhesive sheet according to [6], wherein the plastic film is a release film subjected to release treatment.

[8] An optical film with a pressure-sensitive adhesive comprising a pressure-sensitive adhesive sheet according to any one of [1] to [5] which is bonded to an optical film and an optical film.

[9] The optical film with an adhesive according to [8], wherein the optical film is selected from a polarizing plate and a retardation film.

[10] An optical laminate comprising a glass substrate and an optical film with a pressure-sensitive adhesive according to [8] or [9] laminated on the glass substrate at the pressure-sensitive adhesive sheet side.

The pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive sheet of the present invention comprises 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 site, Since the cross-linking reaction proceeds rapidly and the curing time from the application of the pressure-sensitive adhesive composition to the sheet type to reach a predetermined gel fraction can be shortened, . Therefore, it is possible to shorten the curing time required until the cutting or the like is performed.

In addition, the optical film with a pressure-sensitive adhesive of the present invention, once laminated on a glass substrate, is free from any residue or blur on the surface of the glass substrate after peeling, even if peeled off from the glass substrate together with the pressure- And can be used again as a glass substrate, resulting in excellent reworkability.

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. Since the adhesive layer absorbs and relaxes the stress caused by the dimensional change of the optical film and the glass substrate under an environment in which the optical laminate is heated under high temperature conditions and under repeated heating and cooling conditions, Concentration is relieved, and floating or peeling of the pressure-sensitive adhesive layer against the glass substrate is suppressed. In addition, it is also possible to prevent the concentration of stress in the case of exposure to a high temperature and to suppress the occurrence of opacity and color unevenness.

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 sheet of the present invention is formed in a sheet form from a pressure-sensitive adhesive composition containing an acrylic resin (A) and a crosslinking agent (B). First, each component constituting the pressure-sensitive adhesive composition will be described.

[Acrylic resin (A)]

The pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive sheet, wherein the acrylic resin (A) contains a structural unit derived from the (meth) acrylic acid ester (A-1) represented by the above formula (I) as a main component, Includes a structural unit derived from a (meth) acrylic monomer (A-2) and a structural unit derived from a carboxyl group-containing (meth) acrylic ester (A-3) represented by the above formula (II). Here, the term "(meth) acrylic acid" means either acrylic acid or methacrylic acid, and "(meth)" when referring to (meth) acrylate or the like is also intended. In the present specification, the (meth) acrylic monomer (A-1) represented by the above formula (I) is simply referred to as the "monomer (A- Monomer (A-2) "and the carboxyl group-containing (meth) acrylic acid ester (A-3) represented by the above formula (II) may be simply referred to as" monomer (A-3) ".

R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkyl group having not more than 14 carbon atoms (having 1 to 14 carbon atoms), or an alkyl group having not more than 14 carbon atoms (having a carbon number of 7 to 20) 14). The alkyl group or the aralkyl group represented by R ₂ may be substituted with a hydrogen atom of the group -O- (C ₂ H ₄ O) _n -R ₃ . Herein, n represents 0 or an integer of 1 to 4, and R ₃ represents an alkyl group having 12 or less carbon atoms (having 1 to 12 carbon atoms) or an aryl group having 12 or less carbon atoms (having 6 to 12 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, Linear alkyl esters of acrylic acid (having 1 to 14 carbon atoms), such as lauryl; Branched acrylic acid (3 to 14 carbon atoms) alkyl esters such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; (C 1-14) alkyl (meth) acrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate and lauryl methacrylate ester; And branched methacrylic acid (3 to 14 carbon atoms) alkyl esters such as isobutyl methacrylate, 2-ethylhexyl methacrylate, and dioctyl methacrylate are exemplified.

Of these, n-butyl acrylate is preferable, and specifically, n-butyl acrylate among all the monomers constituting the acrylic resin (A) is 50% by weight or more, and the above-mentioned monomer (A-1) It is preferable to use it so that it satisfies.

Specific examples of the monomer (A-1) in which R ₂ in formula (I) is an (aralkyl group) of ₇ to 14 carbon atoms 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 . In this group -O- (C ₂ H ₄ O) _n -R ₃ , n is an integer of 0 or 1 to 4 as defined above, but is preferably 0, 1 or 2 in particular. R ₃ is an alkyl group having 12 or less carbon atoms (having 1 to 12 carbon atoms) or an aryl group having 12 or less carbon atoms (having 6 to 12 carbon atoms) as defined above and may be branched even when the number of carbon atoms in the alkyl group is 3 or more. Examples of the aryl group constituting R ₃ include, in addition to the phenyl group and the naphthyl group, a phenylalkyl-substituted phenyl group and a biphenylyl (or phenylphenyl) group, including a tolyl group, a xylyl group and an ethylphenyl group. R ₃ is particularly preferably an aryl group thereof.

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. Specifically, Alkoxyalkyl (meth) acrylates of acrylic acid such as 2-methoxyethyl, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2- (2-phenoxyethoxy) ethyl acrylate and 2- Esters, aryloxyalkyl esters of acrylic acid or aryloxyethoxyalkyl-esters of acrylic acid; Methoxyethyl methacrylate, ethoxymethyl methacrylate, 2-phenoxyethyl methacrylate, 2- (2-phenoxyethoxy) ethyl methacrylate, and 2- (o-phenyl Alkoxyalkyl esters of methacrylic acid, aryloxyalkyl esters of methacrylic acid, and aryloxyethoxyalkyl esters of methacrylic acid, and the like.

Each of these monomers (A-1) may be used singly or in combination with one or more other monomers. 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), n-butyl acrylate is at least 50% by weight among all the monomers constituting the acrylic resin (A) and, the (meth) R ₂ is the formula, an alkyl group which is substituted with a hydrogen atom groups _{-O- (C 2 H 4 O)} n -R 3 ( here, n and R ₃ have the same meanings as defined above.) Acrylic acid ester in a proportion of 3 to 15% by weight.

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) acrylic acid (having 1 to 6 carbon atoms) such as 2- (2-hydroxyethoxy) ethyl (meth) acrylate. Among them, 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 an alkylene group and is preferably a linear alkylene group, but it is preferable that the divalent organic group connecting the (meth) acrylic acid moiety CH ₂ ═C (R ₄ ) COO- and the terminal carboxyl group -COOH It may be branched if the carbon number is 3 or more on the premise that the carbon chains are at least 2 in series. Among the compounds represented by formula (II), acrylic acid esters are preferable, and specifically acrylic acid carboxy (1 to 6 carbon atoms) such as 2-carboxyethyl acrylate, 3-carboxypropyl acrylate and 4-carboxybutyl acrylate is exemplified. Of course, the compound obtained by changing the acrylic acid ester thereof to methacrylic acid ester may also be monomer (A-3).

2-carboxyethyl acrylate is usually produced by dimerization of acrylic acid, and in this case, in addition to 2-carboxyethyl acrylate as a main component, acrylic acid itself or an oligomer of acrylic acid or a trimer thereof is obtained, In many cases. It goes without saying that such a mixture containing a carboxyl group-containing (meth) acrylic acid ester (A-2) represented by the formula (II) and other carboxyl group-containing (meth) acrylic monomers may be used for copolymerization.

In the acrylic resin (A) defined 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) having a hydroxyl group is 0.1 to 5% by weight and the content of the structural unit derived from the (meth) acrylic monomer having a carboxyl group represented by the formula (II) The content of the structural unit derived from the monomer (A-3) is 0.01 to 0.2% by weight. By copolymerizing the monomer (A-1), the monomer (A-2) and the monomer (A-3) at such a limited ratio, excellent workability is exhibited and a polarizing plate is obtained. Can be prevented, and a pressure-sensitive adhesive sheet having various durability and reworkability can be obtained. The content of the structural unit derived from the monomer (A-1) is preferably 95% by weight or more, particularly 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 0.12% by weight or less, particularly 0.1% by weight or less. Of course, the total amount of the structural units derived from each of the monomer (A-1), the monomer (A-2) and the monomer (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 monomer (A-1), the monomer (A-2) and the monomer (A-3) described above. Examples of the monomer other than the monomer (A-1), the monomer (A-2) and the monomer (A-3) include unsaturated monomers other than the formula (II) having a polar functional group other than the hydroxyl group, (Meth) acrylate ester, a styrene monomer, a vinyl monomer, a (meth) acrylamide derivative, and a monomer having a plurality of (meth) acryloyl groups in the molecule.

An unsaturated monomer other than the formula (II) having a polar functional group other than the hydroxyl group will be described. The polar functional group other than the hydroxyl group referred to herein may be a free carboxyl group, a heterocyclic group including an epoxy ring, and the like. First, the oligomer of acrylic acid itself or a trimer or more of acrylic acid described in the monomer (A-3) portion 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, 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), and it is preferable that the total amount of the unsaturated monomers having a polar functional group is 5 wt% or less, more preferably 4 wt% or less, particularly 3 wt% or less based on the total monomers constituting the acrylic resin (A) Do.

Next, the (meth) acrylic acid ester 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 acid ester having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, Cyclohexyl methoxyacrylate, cyclohexyl methoxyacrylate, and cyclohexylphenyl acrylate. Specific examples of the methacrylic acid ester having an alicyclic structure include methacrylic acid such as isobornyl, cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, Trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, cyclohexylphenyl methacrylate, and the like.

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

Examples of the vinyl monomer 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.

Examples of (meth) acrylamide derivatives include N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N- (3- hydroxypropyl) , 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- (2-oxo-1-imidazolidinyl) Methyl-1-propanesulfonic acid and the like.

Examples of the monomer having plural (meth) acryloyl groups in the molecule include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, (Meth) acrylate such as ethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and tripropylene glycol di Monomers having two (meth) acryloyl groups; Monomers having three (meth) acryloyl groups in the molecule, such as trimethylolpropane tri (meth) acrylate, and the like.

When the monomer other than the monomer (A-1), the monomer (A-2) and the monomer (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 whole monomers constituting the copolymer (A).

The resin component constituting the pressure-sensitive adhesive composition is a (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 (II), that is, the monomer (A-3). The acrylic resin (A) having a structural unit derived from the monomer (A-1), the monomer (A-2) and the monomer (A-3) at a predetermined ratio may be mixed with an acrylic resin good. The other acrylic resin to be mixed in this case is, for example, one having a structural unit derived from a (meth) acrylic acid ester of the above formula (I) and having no polar functional group. The acrylic resin (A) having a predetermined proportion of the structural units derived from the monomer (A-1), the monomer (A-2) and the monomer (A-3) accounts for 80 wt% % Or more.

The acrylic resin (A) obtained by copolymerization of the monomer mixture containing the monomer (A-1), the monomer (A-2) and the monomer (A-3) has a polystyrene-equivalent value in accordance with gel permeation chromatography (GPC) Has a weight average molecular weight (Mw) in the range of from 1,000,000 to 2,000,000. When the weight average molecular weight in terms of standard polystyrene is more than 1,000,000, the adhesiveness under high temperature and high humidity is improved and the possibility of floating or peeling between the glass substrate and the pressure sensitive adhesive sheet tends to be lowered. . If the weight average molecular weight is less than 2,000,000, even if the size of the optical film bonded to the pressure-sensitive adhesive sheet changes, the pressure-sensitive adhesive layer follows and changes in accordance with the dimensional change. And there is a tendency that cloudiness and color 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) constituting the pressure-sensitive adhesive sheet 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, a polymerization initiator is usually 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. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone and the like. As the thermal polymerization initiator, for example, 2,2'-azobisisobutylonitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile Azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile) Azo compounds such as azobis (2-methylpropionate), and 2,2'-azobis (2-hydroxymethylpropionitrile); Butyl peroxide, lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, Organic peroxides such as neodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl) peroxide; Inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. A redox-type initiator using a peroxide and a reducing agent 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 methods shown above.

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 캜, preferably about 60 to 80 캜, 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 or 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) is blended with 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 which is a polar functional group in the acrylic resin (A) and capable of crosslinking the acrylic resin, and specifically includes an isocyanate compound, Compounds, 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. Further, it is also possible to use 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, or 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 resin, 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 compounds for charging acetylacetone or ethyl acetonate with polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium have.

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 Bis (1-aziridinecarboxamide), triethylene melamine, isophthaloylbis-1- (2-methyl aziridine), tris-1-aziridinylphosphine oxide, Hexamethylene-1,6-bis (1-aziridinecarboxamide), trimethylolpropane tris-? -Aziridinylpropionate, tetramethylolmethane tris-? -Aziridinylpropionate and the like .

Of these crosslinking agents, an isocyanate compound, particularly xylylene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, or an adduct in which these isocyanate compounds are allowed to react with a polyol such as glycerol or trimethylolpropane, A dimer, 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 which allow tolylene diisocyanate to react with polyols, dimers of tolylene diisocyanate, and trimer of tolylene diisocyanate.

The crosslinking agent (B) is compounded 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, and 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 parts by weight or more, particularly 0.1 parts by weight or more, the durability of the pressure-sensitive adhesive sheet tends to be improved. It is preferable that the optical film with the pressure-sensitive adhesive is applied to a liquid crystal display device so that the opacity becomes inconspicuous.

[Other components constituting the pressure-sensitive adhesive composition]

The pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive sheet of the present invention preferably contains a silane compound (C) in order to improve the adhesion between the pressure-sensitive adhesive sheet and the glass substrate. Particularly, It is preferable to contain the compound (C).

Examples of the silane compound (C) 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 (C) may be used.

The silane compound (C) 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 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymers; copolymers containing mercaptopropyl groups;

Mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, Copolymers containing mercaptomethyl groups, such as ethoxysilane-tetraethoxysilane copolymers;

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-methacryloyloxypropyl methyl Copolymers containing methacryloyloxypropyl groups, such as diethoxysilane-tetraethoxysilane copolymer;

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, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, Copolymers containing acryloyloxypropyl groups, such as copolymers;

Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer Polymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetra Vinyl group-containing copolymers, such as methoxy silane copolymers, and the like.

These silane-based compounds are liquids in most cases. The blending amount of the silane compound (C) 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 3 parts by weight, per 100 parts by weight of the solid content of the acrylic resin (A) To 1 part 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, adhesiveness 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-based compound tends to be inhibited from bleeding out from the pressure-sensitive adhesive sheet.

The above-described pressure-sensitive adhesive composition shows good performance, but it is preferable that the pressure-sensitive adhesive composition does not contain an amino group in order to avoid strong adhesion when it comes into contact with a specific release film. It is particularly preferred that it does not have a tertiary amino group.

The pressure sensitive adhesive composition 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). It is also useful to blend an ultraviolet curing compound into the pressure-sensitive adhesive composition and cure the pressure-sensitive adhesive sheet by irradiating ultraviolet rays after forming the pressure-sensitive adhesive sheet to make a harder pressure-sensitive adhesive layer. In particular, when a crosslinking catalyst is mixed with a crosslinking agent in a pressure-sensitive adhesive composition, it is possible to prepare a pressure-sensitive adhesive sheet by curing for a short period of time. In the resulting optical film with a pressure-sensitive adhesive, floating or peeling may occur between the optical film and the pressure- It is possible to suppress foaming or the like from occurring in the sheet, and furthermore, the workability of the sheet can be further improved.

These components constituting the pressure-sensitive adhesive composition are mixed in a state dissolved in a solvent, applied on a suitable substrate, and dried to obtain 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 may be a film formed of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate, or the like, on which a pressure-sensitive adhesive sheet is formed, have.

[Gel fraction of pressure-sensitive adhesive sheet]

The pressure-sensitive adhesive sheet of the present invention is formed by using the pressure-sensitive adhesive composition as described above. By applying the pressure-sensitive adhesive composition as described above, coating it in a sheet form and then leaving it at room temperature for 7 days, the gel fraction after coating in a sheet form after being left at room temperature for 2 days Can be set to 0.8 or more. When the ratio is 0.8 or more, it means that the crosslinking reaction proceeds rapidly after coating in the form of a sheet, and the curing of the pressure-sensitive adhesive is almost completed at the point of two days. That is, this ratio is a criterion of workability. Here, the gel fraction is a value measured according to the following (1) to (4).

(1) A pressure-sensitive adhesive sheet having an area of about 8 cm x about 8 cm and a metal mesh (weight of Wm) made of SUS304 of about 10 cm x about 10 cm are bonded.

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

(3) In the above (2), the staple-fixed mesh is placed in a glass container, and 60 mL of ethyl acetate is added thereto for immersion, and then the glass container is kept at room temperature for 3 days.

(4) The mesh is extracted from the glass container, dried at 120 ° 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 often used after being cured for a certain period of time after its production, and is used in a state in which a 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 depending on the kind of the acrylic resin (A) as 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) If the amount is increased, the gel fraction becomes higher, and therefore, the gel fraction may be adjusted by adjusting the amount thereof.

[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 bonded to at least one surface of the optical film. In the optical laminate with the pressure-sensitive adhesive in the state that the pressure-sensitive adhesive sheet is adhered to the optical film as described above, or the optical laminate with the pressure-sensitive adhesive sheet laminated on the glass substrate, the layer of the pressure-sensitive adhesive sheet is simply referred to as " pressure- There are also cases. 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 polarizing plate is provided with a linearly polarizing plate that absorbs linearly polarized light having a vibration plane in a certain direction and transmits linearly polarized light having a vibration plane orthogonal thereto, reflects linearly polarized light having a vibration plane in a certain direction, A polarizing plate having a property of transmitting linearly polarized light having a polarizing plate, and an elliptically polarizing plate in which a polarizing plate and a retardation film described later are laminated. As a preferable 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, polyarylate, polyimide, polyolefin, cyclic polyolefin, polystyrene, polysulfone, polyethersulfone, polyvinylidene fluoride And a stretched film obtained by stretching a polymer film containing polypropylene, polymethyl methacrylate, liquid crystal polyester, acetyl cellulose, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride, etc. to a degree of 1.01 to 6 times. Among them, a polymer film obtained by uniaxially stretching or biaxially stretching a polycarbonate film or a cyclic polyolefin film is preferable. A uniaxial retardation film, a wide-angle-of-view retardation film, a low-light-elasticity-retardation retardation film, and the like.

A film exhibiting optical anisotropy depending on the application and orientation of the liquid crystalline compound or a film exhibiting optical anisotropy upon application of an inorganic layered compound can also be used as a retardation film. Such a retardation film is referred to as a temperature-compensated retardation film. A film obtained by Shin-Nihon Sekiyu Co., Ltd., which is sold under the trade name "LC film" A rod-shaped liquid crystal sold by FUJIFILM Corporation under the trade name of "WV film " is a film in which the liquid crystal is obliquely oriented, A biaxially oriented type film sold under the trade name of "VAC film" from Kaku Co., and a biaxially oriented type film sold under the trade name "new VAC film" from Sumitomo Chemical Co.,

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 such as 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 triacetyl cellulose 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 adhered to one side or both sides of a polarizing film constituting the linear polarizing plate, 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 the linearly polarizing plate often has a protective film adhered to one or both sides of the polarizing film in many cases. When the pressure-sensitive adhesive sheet according to the present invention is bonded to such an elliptically polarizing plate, it is usually bonded to the retardation film side.

In the optical film with a pressure-sensitive adhesive, it is preferable that the release film subjected to the release treatment as described above is adhered to the surface of the pressure-sensitive adhesive layer and the surface of the pressure-sensitive adhesive layer is protected until use. The optical film with a pressure-sensitive adhesive on which the release film is provided can be obtained by, for example, a method of laminating the obtained pressure-sensitive adhesive sheet onto an optical film by applying the pressure-sensitive adhesive composition onto the release- To form a pressure-sensitive adhesive sheet, and then a peeling film is bonded to the pressure-sensitive adhesive surface to protect the pressure-sensitive adhesive sheet to form an optical film with a pressure-sensitive adhesive.

The thickness of the pressure-sensitive adhesive layer formed on the optical film is not particularly limited, but it 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 floating or peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be lowered, When the thickness of the optical film bonded to the optical film is changed, the thickness of the adhesive layer is varied in accordance with the change in the size of the optical film, so that the brightness of the periphery of the liquid crystal cell and the brightness So that there is a tendency that opacity and color unevenness are suppressed.

When the optical film with a pressure-sensitive adhesive of the present invention adheres to a glass substrate to form an optical laminate, there is a problem that when the optical film is peeled from the glass substrate, the pressure-sensitive adhesive layer is peeled off along the optical film, It is easy to reattach the adhesive film-attached optical film to the glass substrate after peeling, because no fogging or residual residue occurs on the surface of the glass substrate on which the adhesive film is formed. 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 order to laminate the optical film with a pressure-sensitive adhesive on a glass substrate to form an optical laminate, for example, the release film may be peeled off from the optical film with the pressure-sensitive adhesive obtained as described above, and the exposed pressure-sensitive adhesive layer surface may be bonded to the surface of the glass substrate. Examples of the glass substrate include glass substrates for liquid crystal cells, glass for antiglare, and glass for sunglasses. Among them, an optical film (upper polarizing plate) with an adhesive is laminated on a glass substrate on the front side (viewing side) of the liquid crystal cell, and another optical film (lower polarizing plate) with an adhesive is further laminated on the glass substrate on the back side of the liquid crystal cell Is preferable because 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.

For the optical laminate according to the present invention, examples of several suitable layer constructions are shown in a schematic cross-sectional view in Fig. 1 (A), a protective film 3 having a surface treatment layer 2 is adhered to one surface of a polarizing film 1 on a surface opposite to the surface treatment layer 2, The polarizing plate 5 is constituted.

In this example, the polarizing plate 5 also serves as the optical film 10 referred to in the present invention. On the surface of the polarizing film (1) opposite to the protective film (3), a pressure-sensitive adhesive layer (20) is provided to constitute an optical film (25) with a pressure-sensitive adhesive. The surface of the pressure-sensitive adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 serving as a glass substrate to constitute the optical laminate 40.

1B, the first protective film 3 having the surface treatment layer 2 is adhered to one surface of the polarizing film 1 on the surface 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. [ 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 a pressure sensitive adhesive. The surface of the pressure-sensitive adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 serving as a glass substrate to constitute the optical laminate 40.

1C, the protective film 3 having the surface treatment layer 2 is adhered to one surface of the polarizing film 1 on the surface opposite to the surface treatment layer 2, The polarizing plate 5 is constituted. The optical film 10 is formed by adhering the retardation film 7 to the surface of the polarizing film 1 opposite to the protective film 3 with the interlayer adhesive 8 interposed therebetween. 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 bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical laminate 40. [

1D, a first protective film 3 having a surface treatment layer 2 is formed on one surface of the polarizing film 1, and a first protective film 3 having a surface treatment layer 2 is formed on one surface of the polarizing film 1 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. [ The retardation film 7 is adhered to the outside of the second protective film 4 constituting the polarizing plate 5 via the interlayer adhesive 8 so that the optical film 10 is formed. 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 bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical laminate 40. [

In these examples, the first protective film 3 and the second protective film 4 are generally formed of a triacetyl cellulose film, but they may also be composed of the various transparent resin films described 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 example shown in Figs. 1C and 1D, a small-sized liquid crystal display device may have a suitable example of this retardation film 7 as 1 / 4 wave plate. In this case, it is common that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7, which is a 1/4 wavelength plate, are arranged to intersect at almost 45 degrees, but the characteristics of the liquid crystal cell 30 , The angle may be shifted to some extent from 45 degrees. On the other hand, in the case of a large-sized liquid crystal display device such as a television, a phase difference 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 and 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 so as to be almost orthogonal or nearly parallel. When the retardation film 7 is constituted by a 1/4 wavelength plate, a uniaxially or biaxially stretched film is suitably used. When the retardation film 7 is provided for compensation of phase difference of the liquid crystal cell 30 or viewing angle compensation, in addition to the uniaxial or biaxially stretched film, a film oriented in the thickness direction in addition to uniaxial or biaxial stretching, Such as a film in which a phase difference developing substance such as a liquid crystal is coated on the polarizing film and is oriented and fixed, may be used as the retardation film 7.

Likewise, when the polarizing plate 5 and the retardation film 7 are bonded to each other with the interlayer adhesive 8 interposed therebetween, the interlaminar adhesive 8 may be provided with a general Acrylic pressure sensitive adhesive is usually used, but it is of course possible to use the pressure sensitive adhesive sheet specified in the present invention. When the polarizing plate 5 and the retardation film 7 are arranged such that the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 are in a substantially orthogonal or substantially parallel relationship as in the large liquid crystal display device described above, ) Can be roll-to-roll bonded, and in the case where the re-releasability 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 is firmly bonded and can not be peeled off. Examples of such an adhesive include an aqueous adhesive composed of an aqueous solution or an aqueous dispersion and exhibiting an adhesive force by evaporating water as a solvent, an ultraviolet curable adhesive which is cured by ultraviolet irradiation and exhibits an adhesive force.

1 (C) and 1 (D), it is possible to distribute itself to the retardation film 7 itself and to form an optical film with a pressure-sensitive adhesive according to the present invention . The pressure-sensitive adhesive optical film on which the pressure-sensitive adhesive layer is formed on the retardation film can be formed into an optical laminate by bonding the pressure-sensitive adhesive layer to a liquid crystal cell as a glass substrate. In addition to bonding the polarizing plate to the retardation film side, It may be an optical film.

1 shows an example in which the optical film 25 with a pressure-sensitive adhesive is disposed on the visual side of the liquid crystal cell 30, the optical film with a pressure-sensitive adhesive according to the present invention has a back side of the liquid crystal cell, Or on the backlight side. 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. 1 , And other configurations are the same as those shown in Figs. 1 (A) to 1 (D). In this case, various optical films known to be disposed on the back surface 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.

INDUSTRIAL APPLICABILITY 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), a television, a vehicle- Digital cameras, digital video cameras, electronic desk calculators, watches, and the like.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" indicating the amounts used and contents are based on weight unless otherwise specifically acknowledged.

In the following examples, the weight average molecular weight was measured by using a GPC apparatus equipped with four columns of "TSKgel XL" manufactured by TOSOH CORPORATION as a column, and "Shodex GPC (trade name, manufactured by Showa Denko K.K., KF-802 "were connected in series and five were connected in series. Using tetrahydrofuran as the eluent, a sample concentration of 5 mg / mL, a sample introduction amount of 100 mu L, a temperature of 40 DEG C, a flow rate of 1 mL / min Lt; RTI ID = 0.0 > polystyrene. ≪ / RTI >

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

? CEA:? -carboxyethyl acrylate sold by Dai-Celsius Tec Co. under the trade name of "? -CEA". The chemical composition thereof is represented by CH ₂ ═CH (COOCH ₂ CH ₂ ) _n COOH (n = 1 on average), specifically 40% of 2-carboxyethyl acrylate (dimer of acrylic acid) 40% of oligomers and 20% of acrylic acid. Hereinafter, it is indicated as "? CEA" In the table, "" is omitted (the same applies hereinafter).

AA: acrylic acid CH ₂ = CHCOOH.

M-5300: omega -carboxy-polycaprolactone (n?) Having a chemical composition of CH ₂ = CHCOO (C ₅ H ₁₀ COO) _n H is sold by Toagosei Co. under the trade name of "M- 2) Monoacrylate. Hereinafter, it is indicated as "M-5300"

A-SA: 2-acryloyloxyethyl sulfosuccinate having the chemical composition of CH ₂ = CHCOOCH ₂ CH ₂ OCOCH ₂ CH ₂ COOH, which is sold by Shin Nakamura Kagaku Kogyo K.K. under the trade name of "A-SA" Nate. Hereinafter, it is indicated by "A-SA" according to the product name.

[Polymerization Example 1]

81.8 parts of ethyl acetate as a solvent, 70.8 parts of butyl acrylate as monomer (A-1), 20.0 parts of methyl acrylate, and 20.0 parts of acrylic acid 2- (2-ethylhexyl acrylate) as a solvent were added to a reaction vessel equipped with a stirrer, a thermometer, , 1.0 part of 2-hydroxyethyl acrylate as the monomer (A-2) and 0.2 part of "? CEA" as the monomer (A-3) The inside temperature was raised to 55 캜 while replacing air to make it oxygen-free. 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 into the reaction vessel at an addition rate of 17.3 parts / hr while maintaining the internal temperature at 54 to 56 占 폚, and the concentration of the acrylic resin was 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 acrylic resin. The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 16.6 million, and Mw / Mn of 4.0. This is referred to as acrylic resin A. This acrylic resin contains 0.08% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contains 0.08% of a structural unit derived from a trimer of acrylic acid and a structural unit derived from acrylic acid 0.04% of a structural unit.

[Polymerization Example 2]

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 1 except that the amount of butyl acrylate in the monomer composition was changed to 70.9 parts and the amount of "? CEA "was changed to 0.1 part. The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 1,640,000 and an Mw / Mn value of 4.0. This is referred to as acrylic resin B. This acrylic resin contains 0.04% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contains 0.04% of a structural unit derived from a trimer of acrylic acid and a 0.02% of structural units.

[Polymerization Example 3]

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 1 except that the amount of butyl acrylate was changed to 70.92 parts and the amount of "? CEA" was changed to 0.08 part in the monomer composition. The acrylic resin thus obtained had a weight average molecular weight (Mw) of 1,515,000 and a Mw / Mn value of 4.7 in terms of polystyrene according to GPC. This is referred to as acrylic resin C. This acrylic resin contains 0.032% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contains 0.032% of a structural unit derived from a trimer of acrylic acid and a structural unit derived from acrylic acid 0.016% of structural units.

[Polymerization Example 4]

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 1 except that the amount of butyl acrylate was changed to 70.95 parts and the amount of "? CEA" was changed to 0.05 parts in the monomer composition. The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 1,660,000 and an Mw / Mn value of 4.8. This is referred to as acrylic resin D. This acrylic resin contains 0.02% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contains 0.02% of a structural unit derived from a trimer of acrylic acid and a structural unit derived from acrylic acid It contains 0.01% of structural units.

[Polymerization Example 5]

Except that the amount of butyl acrylate in the monomer composition was changed to 70.9 parts and the amount of "? CEA "was changed to 0.1 part, and the same amount of 4-hydroxybutyl acrylate (1.0 part) was used instead of 2-hydroxyethyl acrylate 1, an ethyl acetate solution of an acrylic resin was prepared. The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 16.6 million, and Mw / Mn of 4.0. This is referred to as an acrylic resin E. This acrylic resin contains 0.04% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contains 0.04% of a structural unit derived from a trimer of acrylic acid and a 0.02% of structural units.

[Polymerization Example 6] (for comparison)

The amount of butyl acrylate in the monomer composition was changed to 70.4 parts and the amount of "? CEA "was changed to 0.6 part, and the same amount (8.0 parts) of 2-phenoxyethyl acrylate was used instead of 2- (2-phenoxyethoxy) An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 1. The obtained acrylic resin had a weight average molecular weight (Mw) of 1,690,000 and a Mw / Mn value of 4.2 in terms of polystyrene according to GPC. This is referred to as an acrylic resin V. The acrylic resin contained 0.24% of a structural unit derived from 2-carboxyethyl acrylate corresponding to the monomer (A-3), and further contained 0.24% of a structural unit derived from a trimer of acrylic acid and a structural unit derived from acrylic acid It contains 0.12% of structural units.

[Polymerization Example 7] (for comparison)

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 6 except that the same amount of acrylic acid was used as the monomer composition (0.6 parts) instead of "? CEA ". The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 1,600,000 and a Mw / Mn value of 5.2. This is referred to as an acrylic resin W. The acrylic resin does not contain a structural unit corresponding to the monomer (A-3), but instead contains 0.6% of a structural unit derived from acrylic acid.

[Polymerization Example 8] (for comparison)

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 6 except that the same amount (0.6 parts) of "M-5300" was used instead of "βCEA" in the monomer composition. The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 158,000 and a Mw / Mn of 4.5. This is referred to as acrylic resin X. This acrylic resin also does not contain a structural unit corresponding to the monomer (A-3), and instead, ω-carboxy-polycaprolactone monoacrylate CH ₂ ═CHCOO (C ₅ H ₁₀ COO) _n H 2) containing 0.6% of a structural unit derived from the above.

[Polymerization Example 9] (for comparison)

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 8 except that the amount of butyl acrylate was changed to 69.3 parts and the amount of "M-5300" was changed to 1.7 parts in the monomer composition.

The obtained acrylic resin had a weight average molecular weight (Mw) in terms of polystyrene according to GPC of 1,740,000 and an Mw / Mn value of 3.9. This is referred to as acrylic resin Y. This acrylic resin also does not contain a structural unit corresponding to the monomer (A-3), and instead, ω-carboxy-polycaprolactone monoacrylate CH ₂ ═CHCOO (C ₅ H ₁₀ COO) _n H 2) containing 1.7% of a structural unit derived from the above.

[Polymerization Example 10] (for comparison)

An ethyl acetate solution of an acrylic resin was prepared in the same manner as in Polymerization Example 2, except that the same amount (0.1 part) of "A-SA" was used instead of "βCEA" in the monomer composition. The obtained acrylic resin had a weight average molecular weight (Mw) of 1.73 million and a Mw / Mn of 3.9 in terms of polystyrene according to GPC. This is referred to as an acrylic resin Z. This acrylic resin does not contain a structural unit corresponding to the monomer (A-3), but instead contains a structural unit derived from ₂ -acryloyloxyethyl succinate CH ₂ = CHCOOCH ₂ CH ₂ OCOCH ₂ CH ₂ COOH By weight.

The preparation compositions of the monomers in the above Polymerization Examples 1 to 10 and the list of the weight average molecular weight and Mw / Mn of the obtained acrylic resin are summarized in Table 1.

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

BA: butyl acrylate

MA: methyl acrylate

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

PEA: 2-phenoxyethyl acrylate

2HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

? CEA:? -carboxyethyl acrylate

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

[Containing 40% of 2-carboxyethyl acrylate (n = 1 in the above formula)]

AA: Acrylic acid

M-5300:? -Carboxy-polycaprolactone (n? 2) monoacrylate

A-SA: 2-acryloyloxyethyl succinate

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 and the silane-based compound, respectively (all trade names).

<Cross-linking agent>

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

&Lt; Silane-based compound &

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

[Examples 1 to 5 and Comparative Examples 1 to 6]

(a) Production of pressure-sensitive adhesive

A 20% ethyl acetate solution of the acrylic resin obtained in Polymerization Examples 1 to 10 was used, and the above-mentioned crosslinking agent (Colonate L) was added to each of 100 parts of the solid content in the amounts shown in Table 2, (KBM-403) were mixed, and ethyl acetate was added thereto so that the solid concentration became 13%, thereby obtaining a pressure-sensitive adhesive composition. The crosslinking agent (colonnate 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.

(b) Production of a pressure-sensitive adhesive sheet

Each of the pressure-sensitive adhesive compositions prepared in the above (a) was applied to a releasably treated surface of a polyethylene terephthalate film (trade name "PLR-382050", available from Lintec Co., Ltd., referred to as a separator) subjected to releasing treatment using an applicator And dried at 100 占 폚 for 1 minute to prepare a pressure-sensitive adhesive sheet.

(c) Measurement of gel fraction of the adhesive sheet

The gel fraction was measured by the method described above for each of the pressure-sensitive adhesive sheets prepared in the above (b) after being left at room temperature for 2 days and then left at room temperature for 7 days. Values after leaving for 2 days are shown in the column of &quot; 2nd day &quot; in Table 2, and values after being left for 7 days are shown in column of &quot; Day 7 &quot; in Table 2. The gel fraction after being left for 7 days, The gel fraction ratio is shown in the column of &quot; 2nd day / 7th day &quot;

(d) Production of Polarizer with Adhesive

On one surface of a three-layered polarizing plate in which both surfaces of a polarizing film in which iodine is adsorbed and oriented on polyvinyl alcohol are interposed by a protective film made of triacetylcellulose, a surface opposite to the separator of the pressure- (Pressure-sensitive adhesive surface) was bonded 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.

(e) Fabrication and evaluation of optical laminate

The separator was peeled off from the polarizer with a pressure-sensitive adhesive prepared in (d), and the pressure-sensitive adhesive side was adhered to both sides of a glass substrate for liquid crystal cell (trade name "EAGLE XG" Respectively. The optical laminate was subjected to a heat resistance test for 96 hours under a dry condition at a temperature of 80 캜. Thereafter, the state of expression of white turbidity when light was incident from one polarizing plate side was visually observed. The results are shown in the column of &quot; cloudiness &quot; in Table 2. &lt; tb &gt; &lt; TABLE &gt;

<Expression state of opacity>

◎: No cloudiness can be seen at all.

○: White turbidity is hardly noticeable.

△: White turbidity is slightly visible.

X: White turbidity appears remarkably.

Further, in the case where the heat resistance test in which the heat resistance test was carried out at a temperature of 80 ° C. for 300 hours (indicated as "heat resistance" in Table 2) and the temperature was kept at 60 ° C. and a relative humidity of 90% for 300 hours 2), and the process of lowering the temperature from -70 ° C to -30 ° C and subsequently raising the temperature to 70 ° C is referred to as one cycle (one hour) The optical stacked body after the test was observed with the naked eye for each of the heat shock test (indicated as &quot; inner HS &quot; in Table 2). The results are summarized in Table 2.

<Evaluation Criteria of Heat Resistance Test, Humidity Heat Test and Internal Heat Shock Test>

?: No change in appearance such as floating, peeling, and foaming is observed at all.

○: Almost no change in appearance such as floating, peeling, and foaming is observed.

△: Appearance changes such as floating, peeling, and foaming are slightly visible.

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

(f) 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 (c) above was cut into test pieces having a size of 25 mm x 150 mm. Next, the test piece was adhered to the glass substrate for a liquid crystal cell using a bonding apparatus ("Lamy Parker" (trade name), manufactured by Fuji Plastics Co., Ltd.) on the pressure-sensitive adhesive side and heated at 50 ° C. and 5 kg / ) Under a pressure of 20 MPa for 20 minutes. Then, the resultant was heat-treated at 70 DEG C for 2 hours and then stored in an oven at 50 DEG C for 48 hours. Then, the polarizing plate was peeled from the adhesive test piece at a temperature of 23 DEG C and a relative humidity of 50% at a rate of 300 mm / And peeled off in the direction of 180 DEG (folding back and along the surface of the glass substrate). The state of the surface of the glass substrate after peeling was observed 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>

⊚: no fogging or the like is observed on the surface of the glass substrate at all.

?: Almost no fogging was observed on the surface of the glass substrate.

?: Cloudiness or the like is confirmed on the surface of the glass substrate.

X: Residue of the pressure-sensitive adhesive is confirmed on the surface of the glass substrate.

(Footnote in Table 2: Meaning of symbols representing monomers of acrylic resin)

2HBA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

2CEA: 2-carboxyethyl acrylate (dimer of acrylic acid)

AA-3: Oligomer of trimer or more of acrylic acid

AA: Acrylic acid

M-5300:? -Carboxy-polycaprolactone (n? 2) monoacrylate

A-SA: 2-acryloyloxyethyl succinate

As shown in Tables 1 and 2, a predetermined amount of a crosslinking agent was compounded in acrylic resins A to E in which 2-carboxyethyl acrylate corresponding to the formula (II) was copolymerized in a predetermined amount within the range specified in the present invention, In Examples 1 to 5, a pressure-sensitive adhesive sheet having a high gel fraction ratio on the second day to the gel fraction on the seventh day after coating in a sheet form is provided. Therefore, it is possible to shorten the curing time from being coated in the form of a sheet to the time when processing such as cutting can be performed without any problem, and the workability is excellent. The pressure-sensitive adhesive sheet of these examples provides an optical laminate in which opacity is effectively prevented, and the reheat property is also good. In addition, almost satisfactory results were obtained in terms of heat resistance, heat resistance, and heat shock resistance. In particular, Example 4 has excellent performance in all of workability, anti-cloudiness, heat resistance, heat and humidity resistance, resistance to heat shock, and reworkability.

On the other hand, in Comparative Example 1 using the acrylic resin V having a structural unit derived from 2-carboxyethyl acrylate exceeding 0.2% corresponding to the formula (II) above, it was found that, on the second day after coating the pressure- On the 7th day, the gel fraction is comparable, but the workability is insufficient. Comparative Example 2 using an acrylic resin W copolymerized with acrylic acid instead of the carboxyl group-containing (meth) acrylic ester (A-3) represented by the above formula (II), similar to the above formula (II) Comparative Examples 3 to 6 using the acrylic resin X, Y or Z in which the carboxyl group-containing acrylic acid ester monomer having more atoms than the formula (II) in the main chain and the carboxyl group were copolymerized, , The ratio of the gel fraction on the second day to the gel fraction of 0.8% is less than 0.8, so that the workability is not sufficient. Generally, it was found that the white turbidity tends to be slightly generated by heating.

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet of the present invention is excellent in durability and reworkability, and can shorten the curing time required until the sheet can be processed after forming the sheet, and is excellent in 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 ... ... Phase difference 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 ... ... Optical film with adhesive
30 ... ... Liquid crystal cell (glass substrate)
40 ... ... The optical laminate

Claims (10)

(A) (A-1) 94.8 to 99.89% by weight of a (meth) acrylic acid ester represented by the following formula (I)
(A-2) 0.1 to 5% by weight of a (meth) acrylic monomer having a hydroxyl group, and
(A-3) 0.01 to 0.2% by weight of a carboxyl group-containing (meth) acrylic acid ester represented by the following formula (II)
, 100 parts by weight of an acrylic resin having a weight average molecular weight of 1,000,000 to 2,000,000, and
(B) a crosslinking agent in an amount of 0.01 to 5 parts by weight
A pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing no amino group in a sheet form:

In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group having 14 or less carbon atoms or an aralkyl group having 14 or less carbon atoms, and the hydrogen atom constituting R ₂ is a group -O- (C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4, R ₃ is an alkyl group having 12 or less carbon atoms or an aryl group having 12 or less carbon atoms, R ₄ is a hydrogen atom or a methyl group , And A represents a divalent organic group having 2 to 4 carbon atoms. The pressure-sensitive adhesive sheet according to claim 1, wherein the ratio of the gel fraction after two days from application of the pressure-sensitive adhesive composition in sheet form to the gel fraction after 7 days after application in sheet form is 0.8 or more. 3. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the carboxyl group-containing (meth) acrylic acid ester (A-3) is 2-carboxyethyl acrylate. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the crosslinking agent (B) contains an isocyanate compound. 3. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive composition further contains 0.03 to 2 parts by weight of the silane compound (C). The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive sheet is formed on the plastic film. The pressure-sensitive adhesive sheet according to claim 6, wherein the plastic film is a release film subjected to release treatment. A pressure-sensitive adhesive optical film comprising the pressure-sensitive adhesive sheet according to claim 1 or 2 bonded to an optical film and an optical film. The optical film with an adhesive according to claim 8, wherein the optical film is selected from a polarizing plate and a retardation film. An optical laminate comprising the glass substrate and the pressure-sensitive adhesive optical film according to claim 8 laminated on the glass substrate at the pressure-sensitive adhesive sheet side.

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