TWI579355B - An adhesive composition, an adhesive sheet, an optical film with an adhesive, and an optical laminate - Google Patents

Description

Adhesive composition, adhesive sheet, optical film with adhesive and optical laminate

The present invention relates to an adhesive composition suitable for an optical film, and an optical sheet using the adhesive sheet and the adhesive. The optical film to be used in the present invention includes, for example, a polarizing plate or a retardation film. Further, the present invention relates to an optical layered body which is preferably used for liquid crystal display by laminating an optical film of an adhesive on a glass substrate.

The polarizing plate is widely used by being mounted in a liquid crystal display device. The polarizing plate is generally circulated in a state in which a transparent protective film is formed on two areas of the polarizing film, an adhesive layer is formed on the surface of at least one of the protective films, and a release film is adhered to the adhesive layer. Further, an elliptically polarizing plate is formed by laminating a retardation film on a polarizing plate in a state in which a protective film is bonded to both surfaces of the polarizing film, and the adhesive layer/release film is adhered to the retardation film side in this order. The situation. Further, there is a case where the adhesive layer/release film is 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 provided with an adhesive layer as described above are collectively referred to as an optical film. Before bonding to the liquid crystal cell, the optical film provided with the adhesive layer is cut into a specific size, and the release film is peeled off, and bonded to the liquid crystal cell via the exposed adhesive layer. Such an optical film provided with an adhesive layer has a problem of workability in which the adhesive layer is easily broken at the time of cutting. Therefore, after the adhesive layer is formed, it is usually matured for a sufficient period of time and then used for use, and there is still room for improvement in productivity.

Regarding the adhesive applied to an optical film, the viewpoint of transparency or weather resistance In particular, an acrylic resin produced by copolymerizing a monomer having a polar functional group such as a hydroxyl group or a carboxyl group as a main component of acrylate is often used. A crosslinking agent is blended into such an acrylic resin to impart a necessary cohesive force. Here, the term "crosslinking agent" means a compound having at least two functional groups capable of reacting with a polar functional group constituting the acrylic resin to form a crosslinked structure, and specifically, an isocyanate compound or an epoxy system. a compound, a metal chelate compound, an amine compound, or the like. Among them, an isocyanate compound is widely used as a crosslinking agent.

That is, by blending an isocyanate crosslinking agent having at least two isocyanate groups (-NCO) in the molecule into an acrylic resin having a polar functional group, the functional group and the crosslinking agent in the acrylic resin are passed over time. The isocyanate group reacts to form a crosslinked structure, thereby exhibiting cohesive force and improving workability. Therefore, if the speed of the crosslinking reaction is increased, the time required until sufficient workability is exhibited can be shortened. As a method of increasing the rate of the crosslinking reaction, for example, a method of formulating an amine compound as a crosslinking catalyst is described in paragraph 0046 of Japanese Patent No. 4,370,888 (Patent Document 1). In this case, an isocyanate compound is considered to be suitable. As a crosslinking agent.

Japanese Patent Laid-Open Publication No. 2009-173772 (Patent Document 2) discloses that a decane compound having an amine group and an isocyanate crosslinking agent are blended in an acrylic resin having a hydroxyl group to produce a good process. An adhesive composition for an optical member. Further, in Japanese Patent Laid-Open Publication No. 2009-215528 (Patent Document 3), it is proposed to mix an isocyanate crosslinking agent and a decane coupling agent to have an aromatic ring and a small amount of an amine group. In the acrylic resin having a carboxyl group and/or a hydroxyl group, an adhesive composition for an optical film which exhibits good processability can be obtained.

When the compound having an amine group or the acrylic resin having an amine group is used as a component of the adhesive composition, the adhesive composition having an amine group in the constituent component can be promoted although the crosslinking reaction of the adhesive can be promoted. In the case of contact with a certain release film, there is a problem that the amine group reacts with the release agent in the release film, and the adhesive sheet formed of the adhesive composition and the release film are firmly adhered to become unpeelable. The release film is next.

Further, each of the components constituting the adhesive composition is mixed in a state of being dissolved in a solvent, and after being in a solution state, it is applied onto a suitable substrate, and then dried to form an adhesive sheet. At this time, in order to keep the coatability constant, it is desirable to change the viscosity of the coating solution to a small extent.

On the other hand, the optical film with an adhesive is attached to the liquid crystal cell with the adhesive layer side to form a liquid crystal panel, but in this state, it is set to a high temperature or high temperature and high humidity condition, or is repeatedly heated and cooled. In the case where the size of the optical film changes, the adhesive layer is foamed, or a ridge or peeling occurs between the optical film and the adhesive layer or between the adhesive layer and the liquid crystal cell glass. This kind of inconvenience does not occur and the durability is excellent. Further, 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 periphery of the optical film. As a result, the outer peripheral portion is whitened when black is displayed. The phenomenon of color unevenness is also caused, so it is also sought to suppress such discoloration or color unevenness. Further, the so-called secondary workability is also sought as follows: when the optical film with an adhesive is attached to the liquid crystal cell, it is incomplete. In this case, the optical film is peeled off and then peeled off, and a new film is bonded again. When the film is peeled off, the adhesive layer is peeled off along with the optical film, and the adhesive remains on the unit glass, and no stain or the like occurs.

An object of the present invention is to provide an adhesive composition, an adhesive sheet using the same, and an optical film with an adhesive, which can be made to have a small change in viscosity in a solution state, and has good coating properties. An adhesive sheet or an optical film with an adhesive which is required to have a short curing time after the formation of the adhesive layer and can be processed without problems, and can be made into durability and An optical film with an adhesive which is excellent in secondary workability; and an optical film with an adhesive attached thereto is bonded to a glass substrate represented by a liquid crystal cell to provide an optical laminate.

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and found that by adding a specific amount of a crosslinking agent and an organic acid to the following acrylic resin, adhesion with a small change in viscosity in a solution state can be obtained. In the composition of the above-mentioned acrylic resin, (meth) acrylate is used as a main component, and a (meth)acrylic monomer having a hydroxyl group is contained and a specific atom is separated from a portion to be a main chain by polymerization. A monomer mixture having a carboxyl group (meth) acrylate monomer at a number of positions is obtained by copolymerization. Moreover, the present inventors have found that when the adhesive composition is formed into a sheet shape, a high gel fraction is exhibited with a short aging time, and an adhesive sheet excellent in workability is obtained. Further, the inventors of the present invention have found that when the adhesive sheet is provided on the surface of the optical film as an adhesive layer, it is possible to obtain an adhesive which is excellent in durability and secondary workability, which is represented by workability. The optical film of the agent. The present invention has been completed based on such findings.

That is, the adhesive composition of the present invention contains 100 parts by weight of the acrylic resin (A), 0.01 to 5 parts by weight of the crosslinking agent (B), and 0.03 to 5 parts by weight of the organic acid (C). (A) is a copolymer obtained from a monomer mixture having a weight average molecular weight of 500,000 to 2,000,000, and the monomer mixture comprising: (meth) acrylate (A-1) shown below having a weight of 94.8 to 99.89 %, 0.1 to 5 wt% of the (meth)acrylic monomer (A-2) having a hydroxyl group, and 0.01 to 0.2 wt% of the carboxyl group-containing (meth)acrylate (A-3) shown below.

The above (meth) acrylate (A-1) is represented by the following formula (I): wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group or an aralkyl group having a carbon number of 14 or less, and these groups are formed. The hydrogen atom may be substituted by a group -O-(C ₂ H ₄ O) _n -R ₃ , where 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.

Further, the carboxyl group-containing (meth) acrylate (A-3) is represented by the following formula (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.

A preferred example of the carboxyl group-containing (meth) acrylate (A-3) is 2-carboxyl acrylate. Ethyl ester.

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

Further, the pressure-sensitive adhesive composition may further contain a decane-based compound (D) in an amount of from 0.03 to 2 parts by weight.

The adhesive sheet of the present invention is formed into a sheet shape from any of the above adhesive compositions. The above-mentioned adhesive composition is usually present in a state of being dissolved in a solvent. Therefore, the adhesive composition (solution) is applied onto a suitable substrate, and the solvent is dried and removed to obtain an adhesive sheet.

The adhesive sheet can have a gel fraction of one day after the adhesive composition is applied into a sheet form, and a ratio of a gel fraction of the adhesive composition to a sheet form for 8 days after the adhesive composition is 0.8 or more. . Further, the adhesive sheet can be obtained by coating the adhesive composition into a sheet form for 4 days, and the ratio of the gel fraction to the gel fraction after applying the adhesive composition to the sheet for 8 days becomes 0.97 or more.

In general, the adhesive sheets are preferably formed on a plastic film, and a typical example of the plastic film in this case is a release film which is subjected to release treatment.

Further, the optical film with an adhesive of the present invention is obtained by laminating any of the above adhesive sheets on an optical film. It is advantageous that the optical film includes at least one of a polarizing plate and a retardation film.

Further, the optical layering system of the present invention has the above optical film with an adhesive The adhesive sheet is laminated on the glass substrate.

The adhesive composition of the present invention is less likely to cause viscosity change by blending the organic acid (C) in a solution state, and is excellent in coatability. In addition, the adhesive composition is an acrylic resin (A) having a (meth) acrylate (A-3) having a carboxyl group at a position corresponding to a specific atomic number by a site which is polymerized into a main chain. As the main component, and the crosslinking agent (B) is blended therein, the crosslinking reaction can be rapidly progressed, and the curing time from the application of the adhesive composition to the sheet form to the specific gel fraction can be shortened. Therefore, the processability of the formed adhesive sheet can be improved.

As described above, the optical film with an adhesive of the present invention is excellent in workability, and even if there is a certain problem after lamination on the glass substrate once, even if it is peeled off from the glass substrate together with the adhesive, after peeling The surface of the glass substrate is also less likely to cause paste residue or stains, and can be used again as a glass substrate, and is excellent in secondary workability.

The optical film with an adhesive is formed into an optical laminate for liquid crystal display by, for example, laminating on a glass substrate of a liquid crystal cell. The optical laminate is subjected to high temperature conditions or under moist heat conditions, and in an environment of heating and cooling repeatedly, the adhesive sheet is offset and the stress caused by the change of the size of the optical film and the glass substrate is moderated, so that the optical layer is partially heated. The stress concentration is reduced, and the embossing or peeling of the adhesive layer to the glass substrate can be suppressed. Moreover, it is possible to prevent stress concentration when exposed to high temperatures and to suppress discoloration or color unevenness.

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

[Acrylic resin (A)]

The acrylic resin (A) constituting the adhesive composition of the present invention contains, as a main component, a structural unit derived from the (meth) acrylate (A-1) represented by the above formula (I), and further contains The structural unit of the hydroxy (meth)acrylic monomer (A-2) and the structural unit derived from the carboxyl group-containing (meth) acrylate (A-3) represented by the above formula (II). Here, (meth)acrylic acid may be any of acrylic acid and methacrylic acid, and the term "(meth)" when it is called (meth)acrylate or the like is also the same. In the present specification, the (meth) acrylate (A-1) represented by the above formula (I) may be simply referred to as "monomer (A-1)", and the (meth) acrylate having a hydroxyl group may be used. The monomer (A-2) is simply referred to as "monomer (A-2)", and the carboxyl group-containing (meth) acrylate (A-3) represented by the above formula (II) is simply referred to as " Monomer (A-3)".

In the above 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. Each of the hydrogen atoms of the alkyl group or the aralkyl group represented by R ₂ may also be substituted with a group -O-(C ₂ H ₄ O) _n -R ₃ . Here, n represents an integer of 0 or 1 to 4, and R ₃ represents an alkyl group or an aryl group having a carbon number of 12 or less.

As in the monomer (A-1) In the above formula (I) R ₂ is a non-substituted alkyl group are, specifically, can be exemplified: such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl a linear alkyl acrylate of an ester, n-octyl acrylate, and lauryl acrylate; a branched alkyl acrylate such as isobutyl acrylate, 2-ethylhexyl acrylate, and isooctyl acrylate; a linear alkyl methacrylate of methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate; And branched alkyl methacrylates such as isobutyl methacrylate, 2-ethylhexyl methacrylate, and isooctyl methacrylate.

In the above, it is preferably n-butyl acrylate. Specifically, among all the monomers constituting the acrylic resin (A), n-butyl acrylate is 50% by weight or more, and it satisfies the above-mentioned monomer (A-1). The specification is therefore preferably used.

In the monomer (I), R ₂ in the formula (I) is an aralkyl group, and specific examples thereof include benzyl acrylate or benzyl methacrylate.

Next, the hydrogen atom of the alkyl group or the aralkyl group constituting R ₂ in the formula (I) in the monomer (A-1) is substituted with a group -O-(C ₂ H ₄ O) _n -R ₃ . In the group -O-(C ₂ H ₄ O) _n -R ₃ , n is 0 or an integer of 1 to 4 as defined above, and particularly preferably 0, 1 or 2. Further, R ₃ is an alkyl group or an aryl group having 12 or less carbon atoms as defined above, and may be a straight chain or a branched group as long as the carbon number of the alkyl group is 3 or more. In the case of exemplifying the aryl group constituting R ₃ , in addition to the phenyl group or the naphthyl group, a phenyl group substituted with an alkyl group such as a tolyl group or a xylyl group or an ethylphenyl group, a biphenyl group (or a benzene group) may be mentioned. Phenylphenyl) and the like. R _{3 is} especially preferably the aryl group.

R ₂ in the formula (I) in the monomer (A-1) is an alkyl group, and a hydrogen atom thereof is substituted by a group -O-(C ₂ H ₄ O) _n -R ₃ , specifically, it is exemplified: For example, 2-methoxyethyl acrylate, ethoxymethyl acrylate, 2-phenoxyethyl acrylate, 2-(2-phenoxyethoxy)ethyl acrylate, and 2-(o-phenylene acrylate) An alkoxyalkyl acrylate, an aryloxyalkyl ester or an aryloxy ethoxyalkyl ester of phenoxy)ethyl ester; such as 2-methoxyethyl methacrylate or ethoxy methacrylate Methyl ester, 2-phenoxyethyl methacrylate, 2-(2-phenoxyethoxy)ethyl methacrylate, and 2-(o-phenylphenoxy)ethyl methacrylate An alkoxyalkyl methacrylate, an aryloxyalkyl ester or an aryloxyethoxyalkyl ester or the like.

These monomers (A-1) may be used singly or in combination. As described above, it is also preferred that the monomer (A-1) has n-butyl acrylate as a main component, and other copolymerization of the other (meth) acrylate corresponding to the formula (I) is also effective. One of the preferable compositions of the monomer (A-1) is exemplified by all the monomers constituting the acrylic resin (A), and the n-butyl acrylate is 50% by weight or more, and 3 to 15% by weight. The ratio is formulated as the above formula (I) and wherein R ₂ is an alkane in which a hydrogen atom is substituted with a group -O-(C ₂ H ₄ O) _n -R ₃ (wherein n and R ₃ are as defined above) A base of (meth) acrylate.

The monomer (A-2) is a (meth)acrylic monomer having a hydroxyl group, and examples thereof include 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate. 4-hydroxybutyl methacrylate, 2-(2-hydroxyethoxy)ethyl (meth) acrylate, and the like. Among these, 2-hydroxyethyl acrylate is preferably used as one of the monomers (A-2) constituting the acrylic resin (A).

The monomer (A-3) is represented by the above formula (II). In the 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, preferably a linear alkyl group, but is bonded to a (meth)acrylic acid moiety CH ₂ =C(R ₄ )COO- and a terminal carboxyl group- It is assumed that the carbon chains of COOH are in series and the number of carbon atoms is at least two, and may be branched as long as the number of carbon atoms is three or more. In the formula (II), an acrylate is preferable, and specific examples thereof include 2-carboxyethyl acrylate, 3-carboxypropyl acrylate, and 4-carboxybutyl acrylate. Of course, the compound in which the acrylate is changed to a methacrylate may also be a monomer (A-3).

2-carboxyethyl acrylate is usually produced by dimerization of acrylic acid. In this case, in many cases, the 2-carboxyethyl acrylate as a main component is lower than the acrylic acid itself or a terpolymer of acrylic acid. The mixture of the polymers is obtained and sold directly as a mixture. Thus, of course, the carboxyl group-containing (meth)acrylic monomer may be copolymerized together with the carboxyl group-containing (meth)acrylate (A-3) represented by the formula (II).

In the acrylic resin (A) defined by the present invention, the content of the structural unit derived from the (meth) acrylate represented by the above 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 hydroxyl group-containing (meth)acrylic monomer (A-2) is 0.1 to 5% by weight, and is derived from the carboxyl group-containing (meth)acrylic acid represented by the above formula (II). The content of the structural unit of the ester, that is, the monomer (A-3) is 0.01 to 0.2% by weight. The adhesive composition for providing an adhesive sheet excellent in workability can be obtained by copolymerizing the monomers (A-1), (A-2) and (A-3) in such a ratio. . 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 preferably 3% by weight or less. Further, the content of the structural unit derived from the monomer (A-3) is preferably 0.18% by weight or less, particularly preferably 0.15% by weight or less. Of course, the total amount of the structural units derived from the monomers (A-1), (A-2) and (A-3), respectively, does not exceed 100% by weight.

The acrylic resin (A) used in the present invention may further contain a structural unit derived from a monomer other than the monomers (A-1), (A-2) and (A-3) described above. When an example of a monomer other than the monomers (A-1), (A-2), and (A-3) is exemplified, there is an unsaturated monomer other than the formula (II) having a polar functional group other than a hydroxyl group. a (meth) acrylate having an alicyclic structure in the molecule, a styrene monomer, a vinyl monomer, a (meth) acrylamide derivative, and a plurality of (meth) acrylonitrile groups in the molecule. Monomers, etc.

Hereinafter, an unsaturated monomer other than the formula (II) having a polar functional group other than a hydroxyl group will be described. The polar functional group other than the hydroxyl group as referred to herein may be a free carboxyl group or a heterocyclic group represented by an epoxy ring. The oligomer of acrylic acid itself or a trimer of acrylic acid described above at the monomer (A-3) corresponds to an unsaturated monomer other than the formula (II) having a free carboxyl group. Further, examples of the unsaturated monomer having a heterocyclic group include acryloyl morpholine, vinyl caprolactam, N-vinyl-2-pyrrolidone, and tetrahydroanthracene (meth)acrylate. Ester, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, and the like.

When the unsaturated monomer having a polar functional group other than a hydroxyl group is copolymerized, the (meth)acrylic monomer (A-2) having a hydroxyl group as an essential component, and the above formula (II) are included. In the case of the carboxyl group-containing (meth) acrylate (A-3), the total amount of the unsaturated monomers having a polar functional group is preferably based on all the monomers constituting the acrylic resin (A). 5 The weight% or less is more preferably 4% by weight or less, and particularly preferably 3% by weight or less.

Next, the (meth) acrylate having an alicyclic structure in the molecule will be described. The alicyclic structure refers to a naphthene structure having a carbon number of usually 5 or more, preferably about 5 to 7. Specific examples of the acrylate having an alicyclic structure include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, and trimethyl acrylate. Cyclohexyl ester, t-butylcyclohexyl acrylate, cyclohexyl α-ethoxyacrylate, cyclohexyl phenyl acrylate, and the like. Further, examples of the methacrylate having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentanyl methacrylate, and cyclododecyl methacrylate. And methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, t-butylcyclohexyl methacrylate, cyclohexyl phenyl methacrylate, and the like.

In the case of styrene-based monomers, in addition to styrene, there are, for example, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene. Alkyl styrene of propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene; such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and Halogenated styrene of iodine styrene; further, nitrostyrene, ethyl styrene styrene, methoxy styrene, divinyl benzene, and the like.

Examples of vinyl monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate, such as vinyl chloride or vinyl bromide. Halogenated ethylene; a vinylidene halide of ethylene; a nitrogen-containing aromatic vinyl such as vinyl pyridine, vinyl pyrrolidone, and vinyl carbazole; a conjugated diene of butadiene, isoprene, and chloroprene Further; acrylonitrile, methacrylonitrile, and the like.

Examples of the (meth) acrylamide derivatives include N-hydroxymethyl (meth) acrylamide, N-(2-hydroxyethyl) (meth) acrylamide, and N-(3). -hydroxypropyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-(5-hydroxypentyl)(meth)acrylamide, N-( 6-hydroxyhexyl)(meth)acrylamide, N-(methoxymethyl)(meth)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-( Propyloxymethyl)(meth)acrylamide, N-(butoxymethyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N- Diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-(3-dimethylaminopropyl) (meth) acrylamide, N-(1, 1-dimethyl-3-oxobutyl butyl) (meth) acrylamide, N-[2-(2-o-oxy-1-imidazolidinyl)ethyl](methyl) decylamine 2-propenylamino-2-methyl-1-propanesulfonic acid and the like.

For example, a monomer having a plurality of (meth) acrylonitrile groups in the molecule is exemplified by 1,4-butanediol di(meth)acrylate and 1,6-hexanediol di(meth)acrylic acid. Ester, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylic acid a monomer having two (meth) acrylonitrile groups in the molecule of the ester and tripropylene glycol di(meth) acrylate; for example, three molecules in the molecule of trimethylolpropane tri(meth) acrylate (A) a monomer such as an acrylonitrile group.

Copolymerization of a monomer other than the monomers (A-1), (A-2), and (A-3) which are essential components of the acrylic resin (A) and which does not have a polar functional group In the meantime, the amount is usually 5% by weight or less, more preferably 3% by weight or less, and still more preferably 1% by weight or less based on the total of the monomers constituting the acrylic resin (A).

As described above, the resin component constituting the adhesive composition may be a (meth)acrylic acid having a (meth) acrylate represented by the formula (I), that is, a monomer (A-1) having a hydroxyl group. The acrylic resin (A) having a monomer (A-2) and a carboxyl group-containing (meth) acrylate represented by the formula (II), that is, a structural unit of the monomer (A-3), is mixed in two or more kinds. By. Further, an acrylic resin (A) having a structural unit derived from the monomers (A-1), (A-2) and (A-3) at a specific ratio may be mixed with an acrylic resin different therefrom. Examples of the acrylic resin to be mixed in this case include those having a structural unit derived from the (meth) acrylate of the above formula (I) and having no polar functional group. The acrylic resin (A) having a structural unit derived from the monomers (A-1), (A-2), and (A-3) at a specific ratio is preferably 80% by weight or more of all the acrylic resins. Further, it is preferably 90% by weight or more.

The acrylic resin (A) obtained by copolymerization of a monomer mixture containing the monomers (A-1), (A-2) and (A-3) is a gel permeation (GPC, gel permeation). The measured weight average molecular weight Mw of the standard polystyrene is in the range of 500,000 to 2,000,000. The weight average molecular weight Mw is particularly preferably from 500,000 to 1.7 million. When the weight average molecular weight in terms of standard polystyrene is 500,000 or more, the adhesion under high temperature and high humidity is improved, and the possibility of swelling or peeling between the glass substrate and the adhesive sheet tends to decrease, and there is a second time. The tendency to improve the workability is therefore preferred. Further, if the weight average molecular weight is 2,000,000 or less, there is The lower tendency is that even if the size of the optical film attached to the adhesive sheet changes, the adhesive layer changes in accordance with the dimensional change, so that the difference between the brightness of the peripheral portion of the liquid crystal cell and the brightness of the central portion disappears. It is preferable because it can suppress discoloration or color unevenness. The molecular weight distribution represented by the ratio Mw/Mn of the weight average molecular weight Mw and the number average molecular weight Mn is not particularly limited, but is preferably in the range of, for example, about 3 to 7.

Further, in order to exhibit adhesiveness, the acrylic resin (A) preferably has a glass transition temperature of from -10 to -60C. 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, or a suspension polymerization method. In the production of the acrylic resin, a polymerization initiator is usually used. The polymerization initiator can be used in an amount of about 0.001 to 5 parts by weight based on 100 parts by weight of the total of all the monomers used in the production of the acrylic resin.

As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, or the like can be used. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone and the like. Examples of the thermal polymerization initiator include, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis ( Cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methyl An azo compound of oxyvaleronitrile), 2,2'-azobis(methyl 2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); Lauryl peroxide, tert-butyl hydroperoxide, benzammonium peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate Ester, peroxy neodecanoic acid third Butyl acrylate, tert-butyl peroxypivalate, and organic peroxides of 3,5,5-trimethylhexyl peroxide; inorganic peroxidation such as potassium persulfate, ammonium persulfate, and hydrogen peroxide Things and so on. Further, a redox initiator such as a peroxide and a reducing agent may be used as a polymerization initiator.

As a method of producing an acrylic resin, in the method described above, a solution polymerization method is preferred. Specific examples of the solution polymerization method include mixing a desired monomer and an organic solvent, and adding a thermal polymerization initiator in a nitrogen atmosphere at about 40 to 90 ° C, preferably 50 to 80 ° C. Stir for about 3 to 15 hours. Further, in order to control the reaction, a monomer or a thermal polymerization initiator may be added to the polymerization continuously or intermittently, or may be added in a state of being dissolved in an organic solvent. Here, as the organic solvent, for example, an aromatic hydrocarbon such as toluene or xylene; an ester such as ethyl acetate or butyl acetate; an aliphatic alcohol such as propanol or isopropanol; Methyl ethyl ketone, and ketones of methyl isobutyl ketone.

[Crosslinking agent (B)]

The crosslinking agent (B) and the organic acid (C) are blended into the above acrylic resin (A) to prepare an adhesive composition. The crosslinking agent (B) is a compound having at least two functional groups reactive with a hydroxyl group or a carboxyl group as a polar functional group in the acrylic resin (A) and crosslinked with an acrylic resin, and specifically, An isocyanate type compound, an epoxy type compound, a metal chelate type compound, an aziridine type compound, etc. are illustrated.

The isocyanate compound is a compound having at least two isocyanate groups (-NCO) in the molecule, and examples thereof include toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and benzodiamethylene diisocyanate. An acid ester, hydrogenated benzene dimethylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate or the like. Further, an adduct obtained by reacting the isocyanate compound with a polyol such as glycerin or trimethylolpropane or a dimer or a trimer of the isocyanate compound may be used as an adhesive. The crosslinking agent used. Two or more kinds of isocyanate compounds may be used in combination.

The epoxy compound is a compound having at least two epoxy groups in the molecule, and examples thereof include a bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and glycerin condensed water. Glycerol ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidyl diphenyl ether, N,N,N', N'-tetraglycidyl-m-xylenediamine and the like. Two or more epoxy compounds may be used in combination.

As the metal chelate compound, for example, a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, ruthenium, magnesium, vanadium, chromium, and zirconium may be exemplified with ethyl acetate or ethyl acetonitrile. a compound such as a bit.

The aziridine-based compound has at least two compounds having a three-membered ring skeleton of one nitrogen atom and two carbon atoms in the molecule, and examples thereof include diphenylmethane-4, 4'. - bis(1-aziridinecarbamamine), toluene-2,4-bis(1-aziridinecarboxamide), tri-ethyl melamine, isodecyl bis(1-(2-methyl) Aziridine)), tris(1-aziridinylphosphine oxide), hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane tris (β-aza-propion) Pyridylpropionate), tetramethylolmethanetris(β-aziridine propionate), and the like.

Among the crosslinking agents, an isocyanate compound such as phenylenediethylene diisocyanate, toluene diisocyanate or hexamethylene diisocyanate, or such an isocyanate compound such as glycerin or trishydroxyl is preferably used. An adduct obtained by reacting a polyol of a propane or a dimer or a trimer of the isocyanate compound, a mixture of the isocyanate compounds, and the like.

Examples of the particularly preferable isocyanate-based compound include toluene diisocyanate, an adduct obtained by reacting toluene diisocyanate with a polyhydric alcohol, a dimer of tolylene diisocyanate, and a terpolymer of toluene diisocyanate.

The crosslinking agent (B) is blended in a ratio 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) based on 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, which is preferable. Moreover, when it is 5 parts by weight or less, the discoloration when the optical film with an adhesive is applied to a liquid crystal display device becomes inconspicuous, and it is preferable.

[Organic acid (C)]

The organic acid (C) to be formulated in the adhesive composition is preferably a carboxylic acid represented by the above formula (III). Further, the organic acid (C) is preferably volatilized when the adhesive composition is applied onto a suitable substrate and then dried.

R ₅ in the above formula (III) is a hydrogen atom or an alkyl group or alkenyl group having a carbon number of 4 or less. Examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, acrylic acid, methacrylic acid, crotonic acid, methacrylic acid, and vinyl acetic acid. Among them, formic acid, acetic acid, acrylic acid or methacrylic acid is preferred from the viewpoint of volatility.

The organic acid (C) is blended in a ratio of 0.03 to 5 parts by weight based on 100 parts by weight of the acrylic resin (A). The compounding amount of the organic acid (C) is preferably 0.05 parts by weight or more, particularly 0.1 parts by weight or more, based on 100 parts by weight of the acrylic resin (A). Moreover, it is preferably 2 parts by weight or less, and particularly preferably 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) based on 100 parts by weight of the acrylic resin (A) is 0.03 part by weight or more, particularly 0.1 part by weight or more, the viscosity change of the adhesive composition in a solution state is small, so that it is preferable. Moreover, when it is 5 parts by weight or less, the organic acid (C) is less likely to remain in the adhesive sheet after drying, which is preferable.

[decane compound (D)]

After the adhesive composition of the present invention is formed into an adhesive film or an optical film with an adhesive, it is preferable to contain a decane-based compound (D) in order to improve the adhesion to the glass substrate, and it is preferable to carry out the blending. The decane-based compound (D) is blended in the acrylic resin before the crosslinking.

Examples of the decane-based compound (D) include vinyltrimethoxydecane, vinyltriethoxydecane, vinyltris(2-methoxyethoxy)decane, and 3-glycidoxypropyl group. Trimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-chloropropylmethyldimethoxy Baseline, 3-chloropropyltrimethoxydecane, 3-methylpropenyloxypropyltrimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-glycidoxypropyltrimethoxydecane , 3- Glycidoxypropyl triethoxy decane, 3-glycidoxypropyl dimethoxymethyl decane, 3-glycidoxy propyl ethoxy dimethyl decane, and the like. Two or more kinds of decane-based compounds (D) can also be used.

The decane compound (D) may also be a polyoxyl oligomer type. When the polyfluorene oxide oligomer is represented by a (monomer)-(monomer) copolymer, for example, the following may be mentioned.

Such as 3-mercaptopropyltrimethoxydecane-tetramethoxydecane copolymer, 3-mercaptopropyltrimethoxydecane-tetraethoxydecane copolymer, 3-mercaptopropyltriethoxydecane-tetramethyl a decyl propyl-containing copolymer of a oxydecane copolymer and a 3-mercaptopropyltriethoxydecane-tetraethoxydecane copolymer; such as a mercaptomethyltrimethoxydecane-tetramethoxydecane copolymer , mercaptomethyltrimethoxydecane-tetraethoxydecane copolymer, mercaptomethyltriethoxydecane-tetramethoxydecane copolymer, and mercaptomethyltriethoxydecane-tetraethoxydecane copolymerization Copolymer containing a mercaptomethyl group; such as 3-methacryloxypropyltrimethoxydecane-tetramethoxydecane copolymer, 3-methylpropenyloxypropyltrimethoxydecane-four Ethoxy decane copolymer, 3-methacryloxypropyltriethoxydecane-tetramethoxydecane copolymer, 3-methylpropenyloxypropyltriethoxydecane-tetraethoxy Pyrrolizane copolymer, 3-methacryloxypropylmethyldimethoxydecane-tetramethoxydecane copolymer, 3-methylpropenyloxypropyl Dimethoxydecane-tetraethoxydecane copolymer, 3-methacryloxypropylmethyldiethoxydecane-tetramethoxydecane copolymer, and 3-methylpropenyloxypropane a copolymer of a methyl methacryloxypropyl group containing a methyl dimethyl ethoxy decane-tetraethoxy decane copolymer; For example, 3-propenyloxypropyltrimethoxydecane-tetramethoxydecane copolymer, 3-propenyloxypropyltrimethoxydecane-tetraethoxydecane copolymer, 3-propenyloxypropane Triethoxy decane-tetramethoxydecane copolymer, 3-propenylmethoxypropyltriethoxydecane-tetraethoxydecane copolymer, 3-propenyloxypropylmethyldimethoxy Pyridinium-tetramethoxydecane copolymer, 3-propenylmethoxypropylmethyldimethoxydecane-tetraethoxydecane copolymer, 3-propenyloxypropylmethyldiethoxydecane - a copolymer of 1,4-methoxydecane copolymer and a copolymer of 3-propenyloxypropylmethyldiethoxydecane-tetraethoxydecane having a propyleneoxypropyl group; such as vinyltrimethoxy Pyridinium-tetramethoxydecane copolymer, vinyltrimethoxydecane-tetraethoxydecane copolymer, vinyltriethoxydecane-tetramethoxydecane copolymer, vinyltriethoxydecane- Tetraethoxy decane copolymer, vinyl methyl dimethoxy decane-tetramethoxy decane copolymer, vinyl methyl dimethoxy decane - tetraethoxy decane , Vinyl methyl diethoxy silane-- tetramethoxy silane-copolymer, and vinyl methyl diethoxy silane-- tetraethyl orthosilicate copolymer of vinyl group-containing copolymer.

In most cases, the decane-based compounds are liquid. The blending amount of the decane-based compound (D) in the adhesive composition is usually from 0.01 to 10 parts by weight, preferably from 0.03 to 2 parts, per 100 parts by weight of the solid content of the acrylic resin (A). The part by weight is further preferably 0.03 to 1 part by weight. When the amount of the decane-based compound is 0.01 parts by weight or more, particularly 0.03 parts by weight or more, based on 100 parts by weight of the solid content of the acrylic resin (A), the adhesion between the adhesive sheet and the glass substrate is improved, so that it is preferable. . In addition, when the amount is 10 parts by weight or less, particularly 2 parts by weight or less or 1 part by weight or less, the decane-based compound tends to be prevented from oozing out from the adhesive sheet, which is preferable.

[Preparation of Adhesive Composition]

Each component described above is mixed in a state of being dissolved in a solvent to prepare an adhesive composition. Here, as the solvent, for example, an aromatic hydrocarbon such as toluene or xylene; an ester such as ethyl acetate or butyl acetate; an aliphatic alcohol such as propanol or isopropanol; A group of ethyl ketones and ketones of methyl isobutyl ketone. Further, the adhesive composition exhibits good performance, but in the case of contact with a specific release film, in order to avoid a strong adhesion, it is preferred that the amine group is not contained. It is especially preferred that it does not contain a tertiary amine group.

The adhesive composition dissolved in the above solvent is applied onto a suitable substrate and dried to form an adhesive sheet. The substrate used herein is usually a plastic film, and as a typical example thereof, a release film which has been subjected to release treatment can be mentioned. The release film may be, for example, a surface on which an adhesive sheet is formed on a film of various resins including polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyarylate, or the like. Demolition treatment of oxygen treatment, etc.

The adhesive composition (solution) of the present invention is formed by coating on a suitable substrate, followed by drying and removing the solvent to form an adhesive sheet, and therefore it is preferred that the viscosity change in the solution state is small. The viscosity change can be defined by the following formula using the viscosity η ₁ immediately after the preparation of the adhesive composition and the viscosity η ₂ after 6 hours from the preparation.

Viscosity change (%) = (η _{2 -} η ₁ ) / η ₁ × 100

The viscosity change defined by the formula is preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less. When the viscosity change of the adhesive composition in a solution state is 20% or less, the coating property of the solution is good, which is preferable. Here, the viscosity was measured using a pointer viscometer (LVT) manufactured by Brookfield using a No. 2 spindle at a rotational speed of 12 rpm.

In the adhesive composition in a solution state, a cross-linking catalyst, an antistatic agent, a weathering stabilizer, an adhesive, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and an acrylic resin may be further formulated ( Resin other than A). Among these, there are also those which are insoluble in the solvent constituting the adhesive composition, but the above-mentioned viscosity is also applicable even in the state in which a part of the components are dispersed. When the crosslinking agent and the crosslinking catalyst are blended together in the adhesive composition, the adhesive sheet can be prepared by a short-time aging, and the optical film of the obtained adhesive can be suppressed. The embossing or peeling occurs between the optical film and the adhesive sheet, or foaming is caused in the adhesive sheet, and the secondary workability is further improved.

Further, it is also useful to prepare an ultraviolet curable compound in the adhesive composition, and to form a harder adhesive layer after forming an adhesive sheet and irradiating it with ultraviolet rays.

[Adhesive sheet]

The adhesive sheet of the present invention is also formed into a sheet form from the above-described adhesive composition as described above. Further, the adhesive sheet can be applied to the above-mentioned adhesive composition in the form of a sheet and left at room temperature for one day. The ratio of the gel fraction to the gel fraction after being applied in a sheet form and left at room temperature for 8 days was 0.8 or more. The ratio of 0.8 or more indicates that the crosslinking reaction proceeds rapidly from the application of the sheet, and the curing of the adhesive is sufficiently carried out on the next day. That is, the ratio of the gel fraction becomes a standard of the aging rate. Further, the gel fraction can be applied to a sheet form and left at room temperature for 4 days, and the gel fraction can be applied to the adhesive composition in a sheet form and left at room temperature for 8 days. The ratio of the gel fraction was 0.97 or more. The ratio of 0.97 or more indicates that the hardening of the adhesive is substantially completed at the fourth day. That is, the ratio of the gel fraction is a standard of workability of the adhesive sheet. More preferably, both of them are satisfied, that is, the gel fraction after the adhesive composition is applied in a sheet form and left at room temperature for one day, and is applied to a sheet form and placed at room temperature. The ratio of the gel fraction after the day is 0.8 or more, and the gel fraction after the adhesive composition is applied into a sheet form and left at room temperature for 4 days is applied to the sheet form at room temperature. The ratio of the gel fraction after 8 days of standing was 0.97 or more.

Here, the gel fraction is based on the values measured by the following (1) to (4).

(1) An adhesive sheet having an area of about 8 cm × about 8 cm is bonded to a wire mesh (having a weight of Wm) of about 10 cm × about 10 cm containing SUS304.

(2) The composition obtained in the above (1) was weighed, and the weight was set to Ws, and secondly, it was folded four times in the manner of wrapping the adhesive sheet, and pinned by a stapler (stapler). Weigh and set its weight to Wb.

(3) The wire meshed with the stapler in the above (2) was placed in a glass container, and after immersing it in 60 mL of ethyl acetate, the glass container was stored at room temperature for 3 days.

(4) The screen was taken out from the glass container, dried at 120 ° C for 24 hours, weighed, and the weight was made into Wa, and the gel fraction was calculated based on the following formula.

Gel fraction (% by weight) = [{Wa - (Wb - Ws) - Wm} / (Ws - Wm)] × 100

As described above, in many cases, the adhesive sheet is aged after a certain period of time after the production, and is subjected to a crosslinking reaction to form a state in which a certain degree of gel fraction is exhibited. In the state in which the crosslinking reaction is carried out in such a manner that the gel fraction in the state in which the aging is completed can be, for example, the kind of the acrylic resin (A) or the crosslinking agent as the active ingredient of the adhesive composition forming the same. The amount is adjusted. Specifically, the amount of the monomer having a polar functional group including the monomer (A-2) and the monomer (A-3) in the acrylic resin (A) is increased, or the adhesive composition is improved. When the amount of the crosslinking agent (B) is increased, the gel fraction is increased. Therefore, the gel fraction can be adjusted by adjusting the amounts.

[Optical film with adhesive]

The optical film with an adhesive of the present invention is obtained by laminating an adhesive sheet formed of an adhesive composition as described above on at least one side of the optical film. In the optical layered body in which the adhesive sheet is bonded to the optical film in such a manner as to adhere to the optical film, or the optical layered body in which the adhesive film is laminated on the glass substrate, the adhesive sheet may be used in the present specification. The layer is simply referred to as the "adhesive layer". The optical film used for the optical film with an adhesive is a film which has optical characteristics, and a polarizing plate, a retardation film, etc. are mentioned, for example.

The polarizing plate refers to an optical film that has a function of emitting polarized light with respect to incident light such as natural light. The polarizer has the following: has absorption with a certain side a linear polarizing plate that transmits linearly polarized light to a vibrating surface and transmits a linearly polarized light having a vibrating surface orthogonal thereto; has a linear polarized light that reflects a vibrating surface having a certain direction, and transmits a straight line having a vibrating surface orthogonal thereto A polarizing plate that has a polarizing property; and an elliptically polarizing plate in which a polarizing plate and a retardation film are laminated in the following manner. A preferred example of a polarizing film (sometimes referred to as a polarizing element) that exhibits a function as a polarizing plate, particularly a linear polarizing plate, is to align a dichroic dye such as iodine or a dichroic dye to a single sheet. A shaft-extending polyvinyl alcohol resin film.

The retardation film refers to an optical film exhibiting optical anisotropy, and for example, by including polyvinyl alcohol, polycarbonate, polyester, polyarylate, polyimine, polyolefin, and cyclic polymerization. Olefin, polystyrene, polyfluorene, polyether oxime, polyvinylidene fluoride/polymethyl methacrylate, liquid crystal polyester, acetyl cellulose, ethylene-vinyl acetate copolymer saponified product, polyvinyl chloride, etc. The polymer film is extended to 1.01 to 6 times to obtain a stretched film or the like. Among them, a polymer film in which a polycarbonate film or a cyclic polyolefin film is uniaxially stretched or biaxially stretched is preferable. There is a uniaxial retardation film, a wide viewing angle retardation film, a low photoelastic modulus retardation film, etc., but it is applicable to these.

In addition, a film exhibiting optical anisotropy by application or alignment of a liquid crystal compound or a film exhibiting optical anisotropy by application of an inorganic layer compound can be used as a retardation film. Such a retardation film is called a temperature-compensated retardation film, and is a film which is sold under the trade name "LC Film" by Nippon Oil Co., Ltd., which is a twisted alignment of a rod-shaped liquid crystal; Nippon Oil Co., Ltd. sells a film that is sold under the trade name "NH Film" with a rod-shaped liquid crystal tilting; Fujifilm Co., Ltd. The film is sold under the trade name "WV Film" with a disc-shaped liquid crystal tilting alignment; Sumitomo Chemical Co., Ltd. sells a completely biaxial alignment film under the trade name "VAC Film"; A biaxially oriented film sold by the company under the trade name "new VAC Film".

Further, a protective film can be used as an optical film by adhering to the optical film. As the protective film, a transparent resin film can be used, and examples of the transparent resin include an ethylene glycol-based resin typified by triethylenesulfonyl cellulose or diethyl cellulose, and polymethacrylic acid. A methyl methacrylate resin, a polyester resin, a polyolefin resin, a polycarbonate resin, a polyether ether ketone resin, a polyfluorene resin, or the like represented by a methyl ester. A salicylate-based compound, a benzophenone-based compound, a benzotriazole-based compound, or a third compound may be blended in the resin constituting the protective film. A UV absorber such as a compound, a cyanoacrylate compound or a nickel salt-smelling compound. As the protective film, an ethylene glycol-based resin film such as a triethylenesulfonated cellulose film can be preferably used.

In the optical film described above, in many cases, the linear polarizing plate is used in a state in which a protective film is adhered to one surface or both surfaces of a polarizing film constituting the polarizing film, for example, a polyvinyl alcohol-based resin. Further, the elliptically polarizing plate is provided with a linear polarizing plate and a retardation film. However, in many cases, the linear polarizing plate is in a state in which a protective film is adhered to one surface or both surfaces of the polarizing film. When the adhesive sheet of the present invention is bonded to such an elliptically polarizing plate, it is usually bonded to the retardation film side.

The optical film with an adhesive is preferably adhered to the surface of the adhesive layer by the release film as described above, and the surface of the adhesive layer is protected until use. An optical film having an adhesive attached to the release film as such can be borrowed It is produced by coating the above-mentioned adhesive composition on the release-treated surface of the release film to form an adhesive sheet, and laminating the obtained adhesive sheet on the optical film; coating the adhesive composition An adhesive film is formed on an optical film to form an adhesive sheet, and a release film is bonded to the surface of the adhesive to protect the optical film with an adhesive.

The thickness of the adhesive layer formed on the optical film is not particularly limited, but is usually preferably 30 μm or less, more preferably 10 μm or more, and still more preferably 15 to 25 μm. When the thickness of the adhesive layer is 30 μm or less, the adhesion under high temperature and high humidity is improved, and the possibility of bulging or peeling between the glass substrate and the adhesive layer tends to decrease, and the secondary workability tends to be improved. Preferably, when the thickness is 10 μm or more, there is a tendency that even if the size of the optical film attached thereto changes, the adhesive layer changes in accordance with the dimensional change, so that the peripheral portion of the liquid crystal cell The difference between the brightness and the brightness of the center portion disappears, and discoloration or color unevenness is suppressed, so that it is preferable.

In the case where the optical film with an adhesive of the present invention is adhered to a glass substrate to form an optical laminate, and the optical film is peeled off from the glass substrate, the adhesive layer is peeled off together with the optical film. The surface of the glass substrate connected to the adhesive layer hardly causes stains or residue of the paste, and the optical film of the adhesive can be easily attached to the peeled glass substrate. That is, the secondary workability is excellent.

[optical laminate]

The optical film with an adhesive of the present invention can be laminated on a glass substrate to form an optical laminate. Laminating an optical film with an adhesive on When the optical layered body is formed on the glass substrate, for example, the release film may be peeled off from the optical film of the adhesive obtained by the above-described method, and the exposed adhesive layer may be bonded to the surface of the glass substrate. Examples of the glass substrate include a glass substrate of a liquid crystal cell, a glass for antiglare, and a glass for sunglasses. Wherein, an optical film (upper polarizing plate) with an adhesive is laminated on the glass substrate on the front side (viewing side) of the liquid crystal cell, and another optical film with an adhesive is laminated on the glass substrate on the back side of the liquid crystal cell ( The optical laminate formed of the lower polarizing plate can be used as a panel (liquid crystal panel) for a liquid crystal display device, and thus is preferable. Examples of the material of the glass substrate include soda lime glass, low alkali glass, and alkali-free glass. In the liquid crystal cell, alkali-free glass can be preferably used.

An example of a preferred layer formation in the form of a cross-sectional pattern is shown in Fig. 1 for the optical laminate of the present invention. In the example shown in FIG. 1(A), the protective film 3 having the surface treated layer 2 is adhered to one surface of the polarizing film 1 on the side opposite to the surface treated layer 2 to constitute the polarizing plate 5. In this example, the polarizing plate 5 also becomes the so-called optical film 10 of the present invention. The adhesive layer 20 is provided on the surface of the polarizing film 1 opposite to the protective film 3 to constitute an optical film 25 with an adhesive. Then, the surface of the adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical layered body 40.

In the example shown in FIG. 1(B), the first protective film 3 having the surface treatment layer 2 is adhered to the single side of the polarizing film 1 on the side opposite to the surface treatment layer 2, and the second protective film 4 is applied. The polarizing plate 5 is formed by being adhered to the other surface of the polarizing film 1. In this example, the polarizing plate 5 also becomes the so-called optical film of the present invention. 10. The adhesive layer 20 is provided on the outer side of the second protective film 4 constituting the polarizing plate 5 to constitute an optical film 25 with an adhesive. Then, the surface of the adhesive layer 20 opposite to the polarizing plate 5 is bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical layered body 40.

In the example shown in FIG. 1(C), the protective film 3 having the surface treated layer 2 is adhered to one surface of the polarizing film 1 on the side opposite to the surface treated layer 2 to constitute the polarizing plate 5. The retardation film 7 is adhered to the surface of the polarizing film 1 opposite to the protective film 3 via the interlayer adhesive 8, thereby constituting the optical film 10. The 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 an adhesive. Then, the surface of the adhesive layer 20 on the opposite side to the optical film 10 is bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical layered body 40.

Further, in the example shown in Fig. 1(D), the first protective film 3 having the surface treatment layer 2 is adhered to the single side of the polarizing film 1 on the side opposite to the surface treatment layer 2, and the second protection is applied. The film 4 is adhered to the other side 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, thereby constituting the optical film 10. The 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 an adhesive. Then, the surface of the adhesive layer 20 on the opposite side to the optical film 10 is bonded to the liquid crystal cell 30 as a glass substrate to constitute the optical layered body 40.

In these examples, the first protective film 3 and the second protective film 4 are usually composed of a triacetyl cellulose film, and may be composed of various transparent resin films described above. Moreover, the surface treatment layer formed on the surface of the first protective film 3 can be It is a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and the like. Multiple layers of these may also be provided.

In the case where the retardation film 7 is laminated on the polarizing plate 5 as in the case of the example shown in FIG. 1 (C) and (D), as long as it is a small-sized liquid crystal display device, it is used as the retardation film 7 For a good example, a quarter-wave plate can be cited. In this case, the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 as the quarter-wave plate are usually arranged at substantially 45 degrees, but they are also based on the characteristics of the liquid crystal cell 30. This angle is offset from 45 degrees to some extent. On the other hand, as long as it is a large liquid crystal display device such as a television, a phase difference film having various phase difference values depending on the characteristics of the liquid crystal cell 30 for the purpose of phase difference compensation or viewing angle compensation of the liquid crystal cell 30 can be used. In this case, the absorption axis of the polarizing plate 5 and the slow axis of the retardation film 7 are generally arranged in a substantially orthogonal or substantially parallel relationship. In the case where the retardation film 7 is constituted by a quarter-wave plate, a uniaxial or biaxial stretching film can be preferably used. Further, in the case where the retardation film 7 is provided for the purpose of phase difference compensation or viewing angle compensation of the liquid crystal cell 30, in addition to the uniaxial or biaxially stretched film, it may be in the thickness direction in addition to the uniaxial or biaxial stretching. A film which is an alignment film, a film obtained by applying a phase difference expression material such as a liquid crystal onto a support film, and an alignment film is referred to as an optical compensation film, and is used as the retardation film 7.

Similarly, in the case where the polarizing plate 5 and the retardation film 7 are bonded via the interlayer adhesive 8 as in the case of the examples shown in Figs. 1(C) and (D), the interlayer adhesive 8 is usually a general acrylic adhesive. Of course, the adhesive sheet specified in the present invention can also be used here. As in the case of the large liquid crystal display device as described above, the absorption axis of the polarizing plate 5 and the slow phase axis of the retardation film 7 are substantially orthogonal. In the case of being arranged in a substantially parallel relationship, the polarizing plate 5 and the retardation film 7 may be bonded in a roll-to-roll manner, and in the case where re-peelability between the two is not required, it may be used once firmly. An adhesive which cannot be peeled off by bonding is used instead of the interlayer adhesive 8 shown in (C) and (D) of Fig. 1 . As such an adhesive, for example, a water-based adhesive which is composed of an aqueous solution or an aqueous dispersion, which exhibits an adhesive force by evaporating water as a solvent, and an ultraviolet curing type which exhibits an adhesive force by ultraviolet irradiation hardening Followers and so on.

Further, the adhesive layer 20 formed on the retardation film 7 as shown in (C) and (D) of FIG. 1 can be directly circulated, and can be an optical film of the present invention as an adhesive. The optical film with an adhesive layer formed on the retardation film can be attached to the liquid crystal cell as a glass substrate to form an optical laminate, and the polarizing plate can be attached. On the side of the retardation film, another optical film with an adhesive was formed.

1 shows an example in which the optical film 25 with an adhesive is placed on the viewing side of the liquid crystal cell 30. However, the optical film with an adhesive of the present invention may be provided on the back side of the liquid crystal cell, that is, on the backlight side. When the optical film with an adhesive of the present invention is disposed on the back side of the liquid crystal cell, a protective film having no surface treatment layer may be used instead of the protective film 3 having the surface treatment layer 2 shown in FIG. This is also configured in the same manner as (A) to (D) of Fig. 1 . In this case, various optical films which are well-disposed to the back side of the liquid crystal cell, such as a brightness enhancement film, a light-concentrating film, and a diffusion film, may be provided on the outer side of the protective film constituting the polarizing plate.

As described above, the optical laminate of the present invention can be preferably used for liquid Crystal display device. The liquid crystal display device formed of the optical laminate of the present invention can be used for, for example, a liquid crystal display for a personal computer including a notebook type, a desktop type, a PDA (Personal Digital Assistant), a television, a display for a vehicle, and an electronic Dictionary, digital camera, digital video camera, desktop electronic calculator, clock and so on.

Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by the examples. In the examples, the % and the part of the amount or content used are based on weight unless otherwise specified.

In the following example, the weight average molecular weight is "Shodex GPC KF-802" manufactured by Tosoh Corporation and "Shodex GPC KF-802" manufactured by Showa Denko Co., Ltd. Five roots and a total of five were connected in series as a column, and tetrahydrofuran was used as the eluate at a sample concentration of 5 mg/mL, a sample introduction amount of 100 μL, a temperature of 40 ° C, and a flow rate of 1 mL/min. The value measured by standard polystyrene conversion.

First, an acrylic resin (A) specified in the present invention which is a main component of the adhesive composition, and a polymerization example similar to the acrylic resin other than the one specified in the present invention are disclosed. In the following polymerization examples, the following system containing a carboxyl group is used.

β-CEA: β-carboxyethyl acrylate sold under the trade name “β-CEA” by Daicel-Cytec Co., Ltd. Its chemical composition is expressed as CH ₂ =CH(COOCH ₂ CH ₂ ) _n COOH (n=average 1). Specifically, 2-carboxyethyl acrylate (ie, dimer of acrylic acid) is 40%, and acrylic acid is trimeric. The oligomer above the material was 40% and the acrylic acid was 20%. Hereinafter, the trade name is expressed as "β-CEA". In the following, when it is referred to as "2-carboxyethyl acrylate", it means a dimer of acrylic acid, that is, CH ₂ =CHCOOCH ₂ CH ₂ COOH itself.

[Polymer Example 1]

In a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, and a stirrer, 120 parts of ethyl acetate was added, and the air in the apparatus was replaced with nitrogen gas to prevent oxygen, and the internal temperature was raised to 75 °C. After adding a solution of 0.05 parts of azobisisobutyronitrile (polymerization initiator) to 5 parts of ethyl acetate in a total amount, the internal temperature was maintained at 74 to 76 ° C while being used as a monomer (A- 1) 69.9 parts of butyl acrylate, 20.0 parts of methyl acrylate and 8.0 parts of 2-(2-phenoxyethoxy)ethyl acrylate, 2.0 parts of 2-hydroxyethyl acrylate as monomer (A-2) And a mixed solution of 0.1 part of β-CEA as a monomer (A-3) was added dropwise to the reaction system over 2 hours. Thereafter, the mixture was kept at an internal temperature of 74 to 76 ° C for 5 hours to complete the reaction. Finally, ethyl acetate was added, and the concentration of the acrylic resin was adjusted to 40% to prepare an ethyl acetate solution of an acrylic resin. The obtained acrylic resin had a weight average molecular weight Mw of 680,000 in terms of polystyrene measured by GPC, and Mw/Mn was 4.9. This was made into the acrylic resin A.

[Polymer Example 2]

81.8 parts of ethyl acetate was added to a reaction vessel equipped with a cooling tube, a nitrogen gas introduction tube, a thermometer, and a stirrer, and 69.7 parts of butyl acrylate, 20.0 parts of methyl acrylate, and 2-(2-acrylic acid) of the monomer (A-1) were added. 2-phenoxyethoxy) 8.0 parts of ethyl ester, 2.0 parts of 2-hydroxyethyl acrylate of monomer (A-2), and 0.3 part of β-CEA as monomer (A-3), and the air in the apparatus was replaced with nitrogen gas. Oxygen-free, the internal temperature was raised to 55 °C. Thereafter, a solution obtained by dissolving 0.14 parts of azobisisobutyronitrile (polymerization initiator) in 10 parts of ethyl acetate was added in a total amount. After the addition of the initiator, the temperature was maintained at this temperature for 1 hour, and then the internal temperature was maintained at 54 to 56 ° C, while ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hour. When the concentration became 35%, the addition of ethyl acetate was stopped, and the temperature was kept at this temperature from the start of the addition of ethyl acetate until 12 hours passed. Finally, ethyl acetate was added to adjust the concentration of the acrylic resin to 20%, and an ethyl acetate solution of an acrylic resin was prepared. The obtained acrylic resin had a weight average molecular weight Mw of 1.53 million in terms of polystyrene measured by GPC, and Mw/Mn was 4.2. This was made into the acrylic resin B.

[Polymer Example 3]

The amount of addition of butyl acrylate was changed to 68.85 parts, the amount of addition of 2-hydroxyethyl acrylate was changed to 3.0 parts, and the amount of addition of β-CEA was changed to 0.15 parts, and in the same manner as in Polymerization Example 2. An ethyl acetate solution of an acrylic resin was prepared. The obtained acrylic resin had a weight average molecular weight Mw of 1.44 million in terms of polystyrene measured by GPC, and Mw/Mn was 4.6. This was made into the acrylic resin C.

[polymerization example 4]

The amount of addition of butyl acrylate was changed to 67.9 parts, the amount of addition of 2-hydroxyethyl acrylate was changed to 4.0 parts, and the amount of addition of β-CEA was changed to 0.1 part by weight, and an ethyl acetate solution of an acrylic resin was prepared in the same manner as in the polymerization example 2. The obtained acrylic resin had a weight average molecular weight Mw of 1.47 million in terms of polystyrene measured by GPC, and Mw/Mn was 4.5. This was made into the acrylic resin D.

[Polymer Example 5]

The amount of addition of butyl acrylate was changed to 70.4 parts, and the amount of addition of 2-hydroxyethyl acrylate was changed to 1.0 part, and the same as in the polymerization example 1 except that β-CEA was not added and 0.6 parts of acrylic acid was added instead. In this manner, an ethyl acetate solution of an acrylic resin was prepared. The obtained acrylic resin had a weight average molecular weight Mw of 600,000 in terms of polystyrene measured by GPC, and Mw/Mn was 5.0. This was made into the acrylic resin X.

Table 1 shows a summary of the addition composition of the monomers in the above Polymerization Examples 1 to 5, and the weight average molecular weight and Mw/Mn of the obtained acrylic resin. In addition, in the polymerization example 1, the addition amount of β-CEA is as shown in Table 1, and is 0.1% based on the total of the monomers (that is, the obtained acrylic resin), but in β-CEA Since the 2-carboxyethyl acrylate contained was 40% as described above, the ratio of the structural unit derived from 2-carboxyethyl acrylate in the acrylic resin was 0.04%. Polymerization examples 2 to 4 are also based on this.

(Footnote to Table 1: indicates the meaning of the symbol of the monomer)

(A-1)

BA: butyl acrylate

MA: Methyl acrylate

PEA2: 2-(2-phenoxyethoxy)ethyl acrylate

(A-2)

2HEA: 2-hydroxyethyl acrylate

(A-3)

β-CEA: 40% of 2-carboxyethyl acrylate (dimer of acrylic acid), 40% of oligomer of acrylic acid terpolymer, and 20% of acrylic acid

AA: Acrylic

Next, examples and comparative examples in which an adhesive was prepared using the acrylic resin produced above and applied to an optical film were disclosed. In the following examples, the following were used as the crosslinking agent, the organic acid, and the decane-based compound.

"Coronate L" and "KBM-403" are trade names.

<crosslinker>

Coronate L: an ethyl acetate solution of a trimethylolpropane adduct of toluene diisocyanate (solid content concentration: 75%), obtained from Nippon Polyurethane Co., Ltd.

<organic acid>

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

<decane compound>

KBM-403: 3-glycidoxypropyltrimethoxydecane, liquid, Confidence is obtained by Vietnam Chemical Industry Co., Ltd.

[Examples 1 to 11 and Comparative Examples 1 to 5] (a-1) Manufacture of adhesive compositions 1 to 5

Using the 40% ethyl acetate solution of the acrylic resin A obtained in the polymerization example 1, the above-mentioned crosslinking agent (Coronate L) and organic acid (the amounts shown in Table 2) were mixed with respect to 100 parts of the solid content. The acrylic acid compound and the above-mentioned decane-based compound (KBM-403) were added in an amount of 0.5 parts, and ethyl acetate was added so that the solid content concentration was 28%, thereby preparing the adhesive compositions 1 to 5. Further, the crosslinking agent (Coronate L) is an ethyl acetate solution having a solid content concentration of 75% as described above, and the addition amount shown in Table 2 is the amount of the solid content component.

(a-2) Manufacture of adhesive compositions 6 and 7

The adhesive compositions 6 and 7 were prepared in accordance with the operation of (a-1), except that the 20% ethyl acetate solution of the acrylic resin B obtained in the polymerization example 2 was used.

(a-3) Manufacture of Adhesive Compositions 8 and 9

Adhesive compositions 8 and 9 were prepared in accordance with the operation of (a-1), except that a 20% ethyl acetate solution of the acrylic resin C obtained in Polymerization Example 3 was used.

(a-4) Manufacture of Adhesive Compositions 10 and 11

The adhesive compositions 10 and 11 were prepared in accordance with the operation of (a-1), except that the 20% ethyl acetate solution of the acrylic resin D obtained in the polymerization example 4 was used.

(a-5) Manufacture of adhesive composition 12-15

The adhesive compositions 12 to 15 were prepared in accordance with the operations of (a-1) to (a-4), respectively, except that the organic acid was not mixed.

(a-6) Manufacture of Adhesive Composition 16

The adhesive composition 16 was prepared according to the operation of (a-1) except that the 40% ethyl acetate solution of the acrylic resin X obtained in the polymerization example 5 was not used, and the organic acid was not mixed.

(b) Evaluation of viscosity change of the adhesive composition

For each of the adhesive compositions prepared in the above (a-1) to (a-6), the viscosity was measured by the method described above immediately after preparation and after 6 hours of preparation. The value immediately after preparation is shown in the column of "η ₁ " in Table 2, and the value after 6 hours of preparation is shown in the column of "η ₂ " in Table 2, and (η _{2 -} η ₁ ) / η ₁ × The rate of change of the calculated viscosity of 100 is shown in the column of "viscosity change" in Table 2.

(c) Production of adhesive sheets

Each of the adhesive compositions prepared in the above (a-1) to (a-6) was applied to the release-treated polyethylene terephthalate by an applicator so as to have a thickness of 20 μm after drying. The release film of the ester film [trade name "PLR-382050", obtained from LINTEC Co., Ltd., referred to as a separator] was dried at 100 ° C for 1 minute to prepare an adhesive sheet.

(d) Determination of gel fraction of adhesive sheet

The gel fraction prepared by placing the adhesive sheet prepared in the above (c) at room temperature for one day, after standing for 4 days, and after standing for 8 days, respectively, was measured by the method described above. The value after 1 day of placement is shown in the column of "Day 1" in Table 2. The value after 4 days of placement is shown in the "Day 4" column of Table 2, and the value after 8 days of placement is shown in the table. 2 of the "8th day" column, and will be placed 1 day later The ratio of the gel fraction to the gel fraction after 8 days of placement is shown in the column of "Day 1 / Day 8" in Table 2, and the gel fraction after 4 days of placement was compared with 8 days. The ratio of the gel fraction after that is shown in the column of "Day 4 / Day 8" in Table 2.

(e) Fabrication of a polarizer with an adhesive

The surface (adhesive surface) on the opposite side of the separator of the adhesive sheet prepared in the above (c) is bonded to the polyvinyl alcohol by a protective film containing triethylenesulfonyl cellulose by a bonding machine. After aligning on one surface of a polarizing plate having a three-layer structure on both sides of the iodine-based polarizing film, the film was aged at a temperature of 23 ° C and a relative humidity of 65% for 7 days to prepare a polarizing plate with an adhesive.

(f) Fabrication and evaluation of optical laminates

After peeling the separator from the polarizing plate with an adhesive prepared in the above (e), the adhesive surface is adhered to the glass substrate for liquid crystal cell by orthogonal polarization (product name "EAGLE XG", available from Corning Corporation) On both sides, the optical laminate is made. The optical laminate was subjected to a heat resistance test for 96 hours under dry conditions at a temperature of 80 °C. Thereafter, the state of discoloration at the time of incident light from the side of one polarizing film was visually observed. The results were classified using the following criteria and are shown in the "Decolorization" column of Table 2.

<Decoloration performance status>

◎: Decolorization was not observed at all.

○: Decolorization is hardly noticeable.

△: Decolorization was slightly noticeable.

×: Decolorization was clearly visible.

Further, regarding the optical layered body similar to the above, the following cases are respectively The optical laminate after the test was visually observed: a heat resistance test was carried out under a drying condition of a temperature of 80 ° C for 300 hours (referred to as "heat resistance" in Table 2); and storage was carried out at a temperature of 60 ° C and a relative humidity of 90%. The case of the humidity resistance test for hours (denoted as "moisture resistance" in Table 2); and the temperature from the state of heating to 70 ° C is lowered to -30 ° C, and then the temperature is raised to 70 ° C, and the process is set to 1 cycle (1 hour). The case where the thermal shock resistance test was repeated for 100 cycles (referred to as "HS (hot shock)" in Table 2). The results were classified using the following criteria and summarized in the column of "Durability" in Table 2.

<Evaluation criteria for heat resistance test, damp heat resistance test and thermal shock test>

◎: Appearance changes such as bulging, peeling, and foaming were not observed at all.

○: Appearance changes such as bulging, peeling, and foaming were hardly observed.

△: Appearance changes such as bulging, peeling, and foaming were slightly noticeable.

×: Appearance changes such as bulging, peeling, and foaming were clearly observed.

(g) Secondary processability evaluation of optical film with adhesive

The evaluation of the secondary workability was carried out in the following manner. First, the polarizing plate with an adhesive prepared in the above (e) was cut into a test piece having a size of 25 mm × 150 mm. Then, after the separator was peeled off from the test piece, the adhesive layer [product name "LAMIPACKER" manufactured by FUJIPLA Co., Ltd.] was adhered to the glass substrate for the liquid crystal cell with the adhesive layer side at a temperature of 50 ° C and a pressure of 5 kg / Autoclave treatment was carried out for 20 minutes at cm ² (490.3 kPa). The heat treatment was continued at 70 ° C for 2 hours, and then stored in an oven at 50 ° C for 48 hours, and the polarizing plate and the adhesive layer were combined from the adhesive test piece in an environment of a temperature of 23 ° C and a relative humidity of 50%. The film was peeled off at a speed of 300 mm/min in a direction of 180° (in a direction parallel to the glass surface in a state where the polarizing plate was peeled off and inverted), and the state of the surface of the glass plate was observed and classified by the following criteria. The results are shown together in the column of "secondary workability" in Table 2.

<Evaluation criteria for secondary workability>

◎: No stains were observed on the surface of the glass plate.

○: No stains or the like were observed on the surface of the glass plate.

△: stains and the like were observed on the surface of the glass plate.

×: The residue of the adhesive was observed on the surface of the glass plate.

(footnote to Table 2)

The meaning of the symbol indicating the monomer containing a functional group in the column of "acrylic resin"

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

β-CEA: 40% of 2-carboxyethyl acrylate (dimer of acrylic acid), 40% of oligomer of acrylic acid terpolymer or more, and 20% of acrylic acid (component containing carboxyl group)

AA: Acrylic

Description of the column of "Viscosity"

η ₁ : viscosity of the adhesive composition immediately after preparation

η ₂ : viscosity of the adhesive composition after 6 hours of preparation

Viscosity change (%): (η _{2 -} η ₁ ) / η ₁ × 100

As shown in Table 1 and Table 2, a specific amount of a crosslinking agent is blended in an acrylic resin A obtained by copolymerizing a specific amount of 2-carboxyethyl acrylate corresponding to the above formula (II), and then a specific formulation is prepared. Examples 1 to 11 which constitute an adhesive composition in an amount of an organic acid can provide a viscosity change of the composition, and the gel fraction of the first and fourth days of application to the sheet is condensed with respect to the day 8 A relatively high adhesive sheet with a good gel fraction. Therefore, not only the coating property in the case of coating into a sheet shape is good, but also the aging time until the processing such as cutting can be performed from the time of application until the processing is performed without problems, and the workability is excellent. The adhesive sheet of the examples can also obtain substantially satisfactory results in terms of heat resistance, moist heat resistance and thermal shock resistance.

On the other hand, the acrylic resin has a structural unit derived from 2-carboxyethyl acrylate of the above formula (II), but no organic acid is added. In Examples 1 to 4, the viscosity of the composition was largely changed, and the coating property was not sufficient. Further, in Comparative Example 5 using an acrylic resin X having no structural unit derived from 2-carboxyethyl acrylate of the above formula (II), the gel fraction of the first day of application in a sheet form was used. The ratio of the gel fraction to the eighth day was much lower than 0.8, and the ratio of the gel fraction on the fourth day to the gel fraction on the eighth day was less than 0.97, and it was difficult to say that the workability was sufficient.

Industrial availability

The viscosity change of the adhesive composition of the present invention decreases with the passage of time, showing good coatability. Moreover, the adhesive sheet obtained from the adhesive composition can be shortened to the aging time required after the sheet is formed until processing can be performed, and the workability is excellent, and the durability and secondary workability are also excellent. An optical film provided with the adhesive sheet is suitable for use in a liquid crystal display device.

1‧‧‧ polarizing film

2‧‧‧Surface treatment layer

3‧‧‧(first) protective film

4‧‧‧Second protective film

5‧‧‧Polar plate

7‧‧‧ phase difference film

8‧‧‧Interlayer adhesive

10‧‧‧Optical film

20‧‧‧Adhesive layer (adhesive sheet) attached to liquid crystal cell (glass substrate)

25‧‧‧Optical film with adhesive

30‧‧‧Liquid Crystal Unit (Glass Substrate)

40‧‧‧Optical laminate

1(A) to 1(D) are schematic cross-sectional views showing an example of a preferred layer configuration of an optical layered body of the present invention.

1‧‧‧ polarizing film

2‧‧‧Surface treatment layer

3‧‧‧(first) protective film

4‧‧‧Second protective film

5‧‧‧Polar plate

7‧‧‧ phase difference film

8‧‧‧Interlayer adhesive

10‧‧‧Optical film

20‧‧‧Adhesive layer (adhesive sheet) attached to liquid crystal cell (glass substrate)

25‧‧‧Optical film with adhesive

30‧‧‧Liquid Crystal Unit (Glass Substrate)

40‧‧‧Optical laminate

Claims (14)

An adhesive composition comprising: (A) 100 parts by weight of an acrylic resin, (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 acrylic resin a copolymer obtained from a monomer mixture having a weight average molecular weight of 500,000 to 2,000,000, and the monomer mixture comprising (A-1) a (meth) acrylate represented by the following formula (I): 94.8 to 99.89% by weight (wherein 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, and a hydrogen atom constituting the group may also be via a group -O-(C ₂ H ₄ O) _n -R _{3 is} substituted, wherein n represents 0 or an integer of 1 to 4, R ₃ represents an alkyl group or an aryl group having 12 or less carbon atoms, and (A-2) a (meth)acrylic monomer having a hydroxyl group is 0.1. ~5 wt%, and (A-3) a carboxyl group-containing (meth) acrylate represented by the following formula (II): 0.01 to 0.2% by weight (wherein R ₄ represents a hydrogen atom or a methyl group, and A represents a divalent organic group having 2 to 4 carbon atoms), wherein the organic acid (C) is a carboxylic acid represented by the following formula (III). (wherein R ₅ represents a hydrogen atom or an alkyl group or alkenyl group having 3 or less carbon atoms). The adhesive composition of claim 1, wherein the carboxyl group-containing (meth) acrylate (A-3) is 2-carboxyethyl acrylate. The adhesive composition of claim 1, wherein the crosslinking agent (B) contains an isocyanate compound. The adhesive composition of claim 2, wherein the crosslinking agent (B) contains an isocyanate compound. The adhesive composition of claim 1, which comprises 0.1 to 1.5 parts by weight of the organic acid (C). The adhesive composition according to any one of claims 1 to 5, which further contains (D) a decane-based compound in an amount of 0.03 to 2 parts by weight. An adhesive sheet characterized in that it is formed into a sheet form from the adhesive composition according to any one of claims 1 to 6. The adhesive sheet according to claim 7, wherein the ratio of the gel fraction after applying the adhesive composition to the sheet form for one day is 0.8 or more with respect to the gel fraction after 8 days of application to the sheet form. The adhesive sheet according to claim 7, wherein the ratio of the gel fraction after applying the adhesive composition to the sheet form for 4 days is 0.97 or more with respect to the gel fraction after 8 days of application to the sheet form. The adhesive sheet according to any one of claims 7 to 9, which is formed in a plastic On the membrane. The adhesive sheet of claim 10, wherein the plastic film is a release film which is subjected to release treatment. An optical film with an adhesive, characterized in that the adhesive sheet according to any one of claims 7 to 9 is attached to an optical film. The optical film of the adhesive of claim 12, wherein the optical film is selected from the group consisting of a polarizing plate and a retardation film. An optical laminate characterized in that an optical film with an adhesive as claimed in claim 12 or 13 is laminated on a glass substrate with its adhesive sheet side.