JP2003049143A - Adhesive for optical film and optical film using the adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic adhesive for an optical film, reducing the stress caused by the dimensional change of a member such as the optical film especially having a large sticking area, and preventing leak of light and a picture frame phenomenon, and further to provide an acrylic adhesive sheet for the optical film, using the adhesive. SOLUTION: This adhesive for an optical member comprises a polymer consisting essentially of a (meth)acrylic ester, an antioxidant and a cross-linking agent, and has 30-60% gel fraction. The content of a polymer component having <=10,000 molecular weight measured by a GPC in the sol component of the adhesive is >=25 wt.% based on the amount of the sol component. The optical member is obtained by forming an adhesive layer comprising the adhesive on one or both surfaces of a backing such as a polarization film, a retardation film and an elliptical polarization film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive for an optical film, an optical film using the pressure-sensitive adhesive, and in particular, an optical film constituting a pressure-sensitive adhesive layer-attached polarizing film attached to a liquid crystal cell of a liquid crystal display device. It's about film.

[0002]

2. Description of the Related Art In a liquid crystal cell of a liquid crystal display device, a polarizing film or the like having a three-layer structure in which a triacetate protective film is sandwiched between both sides of a polyvinyl alcohol-based polarizer is generally used as an adhesive layer. Pasted through.

Liquid crystal display devices have been used as display devices for calculators, watches, televisions and various measuring instruments, and have been used under various conditions. Under such circumstances, for example, Japanese Patent Laid-Open No. 3-12471
The publication discloses that a polarizing film having a pressure-sensitive adhesive layer having excellent durability can be obtained by increasing the degree of crosslinking of an acrylic polymer and setting the weight average molecular weight of an uncrosslinked polymer to 100,000 or more. Has been done.

However, increasing the molecular weight of the pressure-sensitive adhesive or increasing the degree of cross-linking so that the pressure-sensitive adhesive layer can withstand use under harsh conditions is to suppress the dimensional change of the polarizing film with the pressure-sensitive adhesive. However, the stress caused by the dimensional change of the polarizing film under high temperature or high temperature and high humidity conditions cannot be sufficiently absorbed and relaxed. For this reason, the residual stress acting on the polarizing film becomes non-uniform, and stress concentration particularly occurs at the peripheral portion, resulting in a problem that light leakage easily occurs in the liquid crystal display device.

Under these circumstances, for example, Japanese Patent Laid-Open No. 2000-109771 uses a pressure-sensitive adhesive composition containing a high-molecular weight polymer and a low-molecular weight polymer to absorb and relax stress caused by dimensional change of a substrate. It is disclosed that it is possible to prevent optical defects under heat and moist heat conditions.
This has made it possible to obtain a polarizing film with a pressure-sensitive adhesive layer that has durability under some conditions, but with the liquid crystal display device expanding to fields of use such as those for in-vehicle use and outdoor measuring instruments, It is required to prevent optical defects under severe conditions. To that end, Japanese Patent Laid-Open No. 2000-109771
It is necessary to extremely reduce the weight average molecular weight of the low molecular weight polymer disclosed in the publication. However, if the weight average molecular weight is lowered, under high temperature conditions, the pressure-sensitive adhesive polymer in the outer peripheral part in contact with oxygen in the air is significantly deteriorated, and the stress relaxation property of the polarizing film is different between the central part and the outer peripheral part. A so-called frame phenomenon occurs in which the hue is different in the outer peripheral portion.

[0006]

DISCLOSURE OF THE INVENTION The present invention relieves stress due to dimensional change of a member such as a polarizing film, a retardation film and an elliptical polarizing film having a particularly large attachment area,
An object is to provide an acrylic pressure-sensitive adhesive for an optical film that suppresses light leakage and a frame phenomenon, and to provide an acrylic pressure-sensitive adhesive sheet for an optical film using the pressure-sensitive adhesive.

[0007]

The pressure-sensitive adhesive for an optical film of the present invention is obtained by cross-linking a pressure-sensitive adhesive composition containing a polymer containing a (meth) acrylic acid ester as a main component, an antioxidant and a cross-linking agent. The adhesive has a gel fraction of 30% or more and 60% or less, and the sol content of the adhesive has a molecular weight of 10,000 or less by GPC, and the polymer component is 25% by weight or more in the sol content. .

The antioxidant is preferably a phenol compound, and the crosslinking agent is preferably an isocyanate compound, an epoxy compound or an aziridine compound. It is preferable that a silane coupling agent is further added to the adhesive.

Further, the optical film of the present invention comprises a support, on one or both sides of which a pressure-sensitive adhesive layer made of the above-mentioned pressure-sensitive adhesive for an optical film is formed. The support may be a polarizing film or a retardation film. It is preferably either a film or an elliptically polarizing film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive for optical films of the present invention comprises a pressure-sensitive adhesive composition containing a polymer containing a (meth) acrylic acid ester as a main component, an antioxidant and a cross-linking agent, which undergo a cross-linking reaction. The adhesive has a gel fraction of 30% or more and 60% or less, and the sol content of the adhesive has a molecular weight of 10,000 or less by GPC of a polymer component of 25% by weight or more in the sol content.

The polymer containing a (meth) acrylic acid ester as a main component used in the present invention is obtained by polymerizing a monomer mixture containing a (meth) acrylic acid ester as a main component by a conventionally known polymerization method. It is a polymer. This monomer mixture contains a (meth) acrylic acid ester as a main component and a functional group-containing monomer having a functional group capable of undergoing a crosslinking reaction with a crosslinking agent as an essential component. Moreover, you may mix | blend other vinyl type monomers.

Examples of the (meth) acrylic acid ester used as the main component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate and iso-butyl (meth) acrylate. Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, Mention may be made of methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate and phenoxyethyl (meth) acrylate. These can be used alone or in combination.

Further, examples of the functional group-containing monomer include
Monomers having carboxyl groups such as (meth) acrylic acid, β-carboxyethyl acrylate, itaconic acid, crotonic acid, maleic acid, fumaric acid and maleic anhydride, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate, chloro
-2-Hydroxypropyl acrylate, diethylene glycol mono (meth) acrylate and hydroxyl group-containing monomers such as allyl alcohol, epoxy group-containing monomers such as glycidyl (meth) acrylate, aminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, etc. Amino group-containing monomers, acrylamide, methylol (meth) acrylamide, methoxyethyl (meth) acrylamide and other amide group-containing monomers, vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane and other silicon-containing monomers And monomers having an acetoacetyl group such as acetoacetoxyethyl (meth) acrylate. These can be used alone or in combination.

Further, as other monomers, aromatic vinyl monomers such as styrene, methylstyrene and vinyltoluene, vinyl acetate, vinyl chloride, (meth) acrylonitrile and the like may be copolymerized alone or in combination.

These monomers are functional group-containing monomers of 0.1 to 100 parts by weight of (meth) acrylic acid ester.
1 to 25 parts by weight is preferable, and 0.5 to 15 parts by weight is more preferable. Other monomers may be blended in an amount of about 0 to 50 parts by weight.

The antioxidant used in the present invention is 2,
6-di-t-butyl-4-methylphenol, n-octadecyl-3
-(3,5-di-t-butyl-4-hydroxyphenol) propionate, triethyleneglycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6 -Hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) ) Propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)-
1,3,5-triazine, 2,2-thio-diethylenebis 〔3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate], 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester and other phenolic antioxidants, dilauryl 3,3′-thiodipropio , Distearyl 3,3'-thiodipropionate, pentaerythritol tetrakis (3-lauryl thiopropionate) and sulfur antioxidants such as 2-mercaptobenzimidazole,
Examples thereof include amine-based antioxidants such as octylated diphenylamine and phosphite-based antioxidants such as tris (2,4-ditertiarybutylphenyl) phosphite. In particular, a phenol compound having a higher effect of suppressing the frame phenomenon is preferable.

The amount of the antioxidant to be added is as follows: Polymer 1 containing the (meth) acrylic acid ester as a main component.
It is 0.001 to 3 parts by weight with respect to 00 parts by weight. When the amount of the antioxidant is less than 0.001 part by weight, the adhesive polymer in the outer peripheral portion of the polarizing film is significantly deteriorated under high temperature conditions, so that a frame phenomenon is likely to occur. On the other hand, when the amount of the antioxidant exceeds 3 parts by weight, the compatibility with the pressure-sensitive adhesive decreases, so that peeling of the polarizing film occurs under high temperature or high temperature and high humidity conditions.

Examples of the cross-linking agent used in the present invention include isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds and amine compounds. Particularly, an isocyanate compound, an epoxy compound or an aziridine compound is preferable. These crosslinking agents may be used alone or in combination of two or more kinds.

Examples of the isocyanate compound include tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate and the like. Isocyanate monomers and isocyanate compounds obtained by adding these isocyanate monomers to trimethylolpropane and the like, isocyanurate compounds, burette type compounds, and further known polyether polyols and polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc. Examples of urethane prepolymer type isocyanates Can.

As the epoxy compound, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis (N,
N-diglycidylaminomethyl) cyclohexane, N, N, N ',
N'-tetraglycidyl-m-xylylenediamine, N, N, N ', N'-
Tetraglycidylaminophenylmethane, triglycidyl isocyanurate, mN, N-diglycidylaminophenylglycidyl ether, N, N-diglycidyltoluidine, N,
Examples thereof include N-diglycidyl aniline.

Examples of the aziridine-based cross-linking agent include diphenylmethane-4,4'-bis (1-aziridinecarboxamide),
Trimethylolpropane tri-β-aziridinyl propionate, tetramethylolmethane tri-β-aziridinyl propionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylene melamine, bisiso Phthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, trimethylolpropane tri-
Examples include β- (2-methylaziridine) propionate.

The amount of the cross-linking agent to be added is 100% of the polymer containing the (meth) acrylic acid ester as a main component.
It is 0.001 to 5 parts by weight with respect to parts by weight. When the amount of the cross-linking agent is less than 0.001 part by weight, the gel fraction tends to be less than 30%, the cohesive force of the obtained pressure-sensitive adhesive is low, and foaming is likely to occur under high temperature conditions. Further, when the amount of the cross-linking agent exceeds 5 parts by weight, the gel fraction tends to exceed 60% and the resulting pressure-sensitive adhesive becomes inferior in stress relaxation property, and light leakage and peeling under high temperature and high temperature and high humidity conditions occur. Occurs.

In the pressure-sensitive adhesive for optical films of the present invention, the polymer component having a molecular weight of 10,000 or less in the sol component (uncrosslinked polymer) by gel permeation chromatography (GPC method) is 25% by weight or more. Molecular weight in sol 1
If the amount of the polymer component is less than 25% by weight, the pressure-sensitive adhesive obtained will be inferior in stress relaxation property, and light leakage will occur under high temperature and high temperature and high humidity conditions.

A silane coupling agent is preferably blended in the pressure-sensitive adhesive for optical members of the present invention. As the silane coupling agent, a silicon compound having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-
Amino group-containing silicon compounds such as aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane and N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxy Examples thereof include methoxysilane.

The optical film of the present invention has a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive for optical film on one side or both sides of a support. Examples of the support include a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, and the like. In particular, the polarizing film, the retardation film or the elliptically polarizing film is the stress of the pressure-sensitive adhesive for the optical film. More relaxed.

[0026]

EXAMPLES The present invention will be described more specifically by showing examples, but the present invention is not limited thereto.

<Production Example 1> Acrylic polymer solution A
Preparation of n-butyl acrylate (n-BA) 95 parts by weight, acrylic acid (AA) 5 parts by weight, ethyl acetate 100 parts by weight and azobisisobutyronitrile (AIBN) 0.2 parts by weight were placed in a reaction vessel, After the air in the reaction vessel was replaced with nitrogen gas, the reaction vessel was stirred at room temperature in a nitrogen atmosphere.
The temperature was raised to 0 ° C. and the reaction was performed for 12 hours. After the reaction, it was diluted with ethyl acetate to give an acrylic polymer solution A having a solid content of 20%.
(Weight average molecular weight 1.5 million) was obtained.

<Production Example 2> Acrylic polymer solution B
Preparation of n-butyl acrylate (n-BA) 95 parts by weight, 2-hydroxyethyl acrylate (2-HEA) 5 parts by weight, ethyl acetate 90 parts by weight and benzoyl peroxide 0.2 parts by weight were placed in a reaction vessel. After replacing the air in the reaction vessel with nitrogen gas, the temperature of the reaction vessel was raised to 67 ° C. in a nitrogen atmosphere with stirring and the reaction was carried out for 15 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain an acrylic polymer solution B having a solid content of 20% (weight average molecular weight 1.3 million).

<Production Example 3> Acrylic polymer solution C
Preparation of n-BA 99.5 parts by weight, 2-HEA 0.5 parts by weight, toluene 100 parts by weight, n-dodecyl mercaptan as a chain transfer agent 5 parts by weight, and AIBN 3 parts by weight are put in a reaction container, and After replacing the air with nitrogen gas, the temperature of this reaction vessel was raised to 100 ° C. in a nitrogen atmosphere with stirring and the reaction was carried out for 6 hours. After the reaction, dilute with toluene,
An acrylic polymer solution C (weight average molecular weight 9000) having a solid content of 40% was obtained.

<Production Example 4> Acrylic polymer solution D
Preparation of n-BA 100 parts by weight, toluene 100 parts by weight, α-methylstyrene dimer 5 parts by weight as a chain transfer agent, and AIBN 2 parts by weight were placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas, In a nitrogen atmosphere with stirring, the temperature of this reaction vessel was raised to 100 ° C. and the reaction was performed for 6 hours. After the reaction, the mixture was diluted with toluene to obtain an acrylic polymer solution D (weight average molecular weight 7,000) having a solid content of 40%.

<Production Example 5> Preparation of acrylic polymer E 99.5 parts by weight of n-BA, 5 parts by weight of AA, and 3 parts by weight of n-dodecyl mercaptan as a chain transfer agent were placed in a reaction container, and air in the reaction container was placed in the reaction container. Was replaced with nitrogen gas, and then heated to 60 ° C. in a nitrogen atmosphere with stirring. Then, as a polymerization initiator, 2,2'-azobis (4-methoxy-2,4
-Dimethylvaleronitrile) (0.005 parts by weight) was added with stirring to uniformly mix. After the addition of the polymerization initiator, the temperature of the reaction system increased, and when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 110 ° C., and then gradually started to decrease. The temperature in the system was forcibly cooled to 60 ° C. with a water bath. After forced cooling, 2,2'-azobis (4-methoxy) was added.
0.002 parts by weight of -2,4-dimethylvaleronitrile) was added under stirring to uniformly mix. After the second charge of initiator,
The temperature of the reaction system rose, but when the polymerization reaction was continued without cooling, the temperature of the reaction system reached 105 ° C. Then, the temperature of the reaction system was forcibly cooled to 75 ° C. with a water bath.

Further, 0.01 part of dimethyl 2,2'-azobis (2-methylpropionate) was added. When the temperature of the reaction system rose, but the polymerization reaction was continued without cooling,
The temperature of the reaction system reached 120 ° C. The temperature of the reaction system was cooled to 110 ° C. with a water bath. Continuing, polymerization initiator 1,
1'-azobis (cyclohexane-1-carbonitrile) 0.1
After adding 5 parts by weight of the mixture under stirring and performing a polymerization reaction for 2 hours,
The reaction system was cooled to room temperature with a water bath, and the solid content was 99% by weight.
Polymer E (weight average molecular weight 4000) was obtained.

<Production Example 6> Acrylic polymer solution F n-BA 99.5 parts by weight, 2-HEA 0.5 parts by weight, ethyl acetate 50 parts by weight, toluene 100 parts by weight, and AIB
N0.3 was placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas. Then, the temperature of the reaction vessel was raised to 80 ° C. in a nitrogen atmosphere with stirring, and the reaction was performed for 10 hours. After the reaction, the mixture was diluted with toluene to obtain an acrylic polymer solution F (weight average molecular weight 100,000) having a solid content of 40%.

<Production Example 7> 100 parts by weight of acrylic polymer solution G n-BA, 100 parts by weight of ethyl acetate, 50 parts by weight of toluene, and AIBN 0.2 were placed in a reaction vessel, and the air in the reaction vessel was replaced with nitrogen gas. After the replacement, the reaction vessel was heated to 72 ° C. in a nitrogen atmosphere with stirring and reacted for 10 hours. After the reaction, the mixture was diluted with ethyl acetate to obtain an acrylic polymer solution G (weight average molecular weight 300,000) having a solid content of 40%.

<Preparation of pressure-sensitive adhesive sheet for optical film> A polarizing film was used as a support, and a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on a polyester film obtained by subjecting the pressure-sensitive adhesive composition containing the above acrylic polymer solution to a release treatment. It was transferred to a support and aged for 7 days under the conditions of a temperature of 23 ° C. and a humidity of 65% to produce an optical film pressure-sensitive adhesive sheet.

<Measurement of gel fraction> The gel fraction is measured at a temperature of 23.
About 0.1 g of the pressure-sensitive adhesive on the optical film pressure-sensitive adhesive sheet that had been aged for 7 days at a temperature of 65 ° C. and a humidity of 65% was collected in a sample bottle, 30 cc of ethyl acetate was added, and the mixture was shaken for 24 hours. The content of (1) was filtered off with a 200-mesh stainless steel wire net, the residue on the wire net was dried at 100 ° C. for 2 hours, and the dry weight was measured, and determined by the following formula [I].

[0037]

[Equation 1]

<Measurement of molecular weight and molecular weight distribution of sol content> For the pressure-sensitive adhesive on the optical film pressure-sensitive adhesive sheet aged for 7 days at a temperature of 23 ° C. and a humidity of 65%, gel permeation chromatography was performed under the following measurement conditions. The weight percentage of the molecular weight of 10,000 or less in the uncrosslinked polymer (sol content) was determined by means of photography. Device name: Tosoh Corporation, HLC-8120 Column: Tosoh Corporation, G7000HXL 7.8mm ID x 30cm 1 GMHXL 7.8mm ID x 30cm 2 G2000HXL 7.0mm ID x 30cm 1 sample concentration: 1.5mg Dilute with tetrahydrofuran so that the concentration becomes / ml Mobile phase solvent: Tetrohydrofuran Flow rate: 1.0 ml / min Column temperature: 40 ° C

[0039]

Example 1 100 parts by weight of the solid content of the polymer solution A and 60 parts by weight of the solid content of the polymer solution C were mixed, and 0.1 part by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) as a crosslinking agent and As an antioxidant, 0.2 parts by weight of a phenolic compound [pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]] was added, and the mixture was stirred well to produce an adhesive. A composition was obtained. After applying it to a polyester film that has been subjected to a peeling treatment and drying it to form a 25 μm pressure-sensitive adhesive layer, transfer it to one side of a polarizing film, and age it for 7 days at a temperature of 23 ° C. and a humidity of 65% to obtain an optical film. An adhesive sheet was obtained. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0040]

Example 2 100 parts by weight of the solid content of the polymer solution A and 20 parts by weight of the solid content of the polymer solution D were mixed, and 0.15 parts by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) and an antioxidant were added to the mixture. As a phenolic compound [triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl)]
Propionate]] 0.1 part by weight was added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to form a pressure-sensitive adhesive layer having a thickness of 25 μm, which is then transferred to one side of a polarizing film at a temperature of 23
It was aged for 7 days at a temperature of 65 ° C. and a humidity of 65% to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0041]

Example 3 100 parts by weight of the solid content of the polymer solution B and 40 parts by weight of the solid content of the polymer solution D were mixed, and 0.1 part by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) and an antioxidant were added to the mixture. As a phenolic compound [triethylene glycol-bis-
0.2 parts by weight of [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] was added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to form a 25 μm pressure-sensitive adhesive layer, which is then transferred to one side of a polarizing film at a temperature of 23 ° C.
It was aged for 7 days under the condition of a humidity of 65% to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0042]

Example 4 100 parts by weight of the solid content of the polymer solution A and 70 parts by weight of the solid content of the polymer E were mixed, and an epoxy compound (N, N, N ', N'-tetraglycidyl-m-as a crosslinking agent was added thereto.
Xylylenediamine) 0.02 part by weight, phenolic compound (2,6-di-t-butyl-4-methylphenol) 0.2 part by weight as an antioxidant, and silane coupling agent (3-glycidoxy) Propyltrimethoxysilane) 0.2
Parts by weight were added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to form a pressure-sensitive adhesive layer of 25 μm, which is then transferred to one side of a polarizing film, and the temperature is 23 ° C. and the humidity is 65%.
It was aged for a day to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0043]

Example 5 100 parts by weight of the polymer solution A and 50 parts by weight of the polymer solution D were mixed, and 0.05 part by weight of an aziridine compound (trimethylolpropane tri-β-aziridinyl propionate) as a crosslinking agent was added to the mixture. Phenolic compound (3,5-di-t-butyl-4-hydroxy)
-Benzylphosphonate-diethyl ester) 0.5 part by weight and a silane coupling agent (3-aminopropyltrimethoxysilane) 0.2 part by weight were added and well stirred to obtain an adhesive composition. It is applied to a polyester film that has been subjected to a peeling treatment and dried to provide a 25 μm pressure-sensitive adhesive layer, which is then transferred to one side of a polarizing film and the temperature is set to 2
It was aged for 7 days under the conditions of 3 ° C. and humidity of 65% to obtain an optical film pressure-sensitive adhesive sheet. Regarding the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, gel fraction and molecular weight 1 in sol
The weight percentage of less than ten thousand polymer components was measured. The results are shown in Table 1.

[0044]

Comparative Example 1 Example 1 except that no antioxidant was added
An optical film adhesive sheet was obtained in the same manner as. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0045]

Comparative Example 2 An optical film pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount of the polymer solution C was changed to 10 parts by weight. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0046]

Comparative Example 3 An optical film pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the isocyanate compound was changed to 5.5 parts by weight. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0047]

Comparative Example 4 An optical film pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the amount of the isocyanate compound was 0.0008 parts by weight. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0048]

Comparative Example 5 100 parts by weight of the solid content of the polymer solution A and 10 parts by weight of the solid content of the polymer solution F were mixed, and 0.1 part by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) was added as a crosslinking agent. The mixture was added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to 25 μm
After the pressure-sensitive adhesive layer was prepared, it was transferred to one side of the polarizing film and aged for 7 days under the conditions of temperature 23 ° C. and humidity 65% to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0049]

Comparative Example 6 100 parts by weight of the solid content of the polymer solution A and 20 parts by weight of the solid content of the polymer solution G were mixed, and 0.1 part by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) was added as a crosslinking agent. The mixture was added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to 25 μm
After the pressure-sensitive adhesive layer was prepared, it was transferred to one side of the polarizing film and aged for 7 days under the conditions of temperature 23 ° C. and humidity 65% to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0050]

Comparative Example 7 An optical film pressure-sensitive adhesive sheet was obtained in the same manner as Comparative Example 6 except that the solid content of the polymer solution G was changed to 60 parts by weight. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0051]

Comparative Example 8 100 parts by weight of the solid content of the polymer solution B and 10 parts by weight of the solid content of the polymer solution G were mixed, and 0.15 parts by weight of an isocyanate compound (trimethylolpropane tolylene diisocyanate) was added as a crosslinking agent. The mixture was added and well stirred to obtain an adhesive composition. It is applied to a peeled polyester film and dried to 25 μm
After the pressure-sensitive adhesive layer was prepared, it was transferred to one side of the polarizing film and aged for 7 days under the conditions of temperature 23 ° C. and humidity 65% to obtain an optical film pressure-sensitive adhesive sheet. With respect to the pressure-sensitive adhesive of the obtained optical film pressure-sensitive adhesive sheet, the gel fraction and the weight percentage of the polymer component having a molecular weight of 10,000 or less in the sol content were measured. The results are shown in Table 1.

[0052]

[Table 1]

<Durability Test of Optical Film Adhesive Sheet>
The 15-inch size optical film pressure-sensitive adhesive sheets obtained in Examples 1 to 5 and Comparative Examples 1 to 8 had a thickness of 0.5 mm.
Laminated rolls were attached to both surfaces of the non-alkali glass plate in (2) so as to form a crossed Nicol. Then, 50 ℃,
It was held in an autoclave at 5 atm for 20 minutes for adhesion.
The sample thus obtained was heated to 120 ° C. and 80 ° C. 90
After being left for 500 hours under the condition of% RH, the optical film was visually observed for foaming and peeling, as well as light leakage and a frame phenomenon. The results are shown in Table 2. In the table, “◯” means that there is no problem in practical use, “Δ” means that a problem may occur in practical use, and “x” means that there is a problem in practical use. The light leakage and the frame phenomenon of Comparative Example 3 and Comparative Example 7 were not observable because the peeling of the adhesive sheet was large.

[0054]

[Table 2]

The optical member in which the pressure-sensitive adhesive of Examples 1 to 5 and the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive were formed on one surface of the polarizing film, even if the size was 15 inches and the bonding area was large,
Under high temperature atmosphere of 120 ° C for 500 hours and 80 ° C,
No peeling, foaming, light leakage, or frame phenomenon occurred in an atmosphere of high temperature and high humidity of 90% RH for 500 hours.

On the other hand, in Comparative Example 1, the frame phenomenon occurs because the adhesive does not contain an antioxidant. In Comparative Example 2, since the polymer component having a molecular weight of 10,000 or less in the sol content is small, light leakage occurs under high temperature conditions. In Comparative Example 3, because of the high gel fraction, large peeling occurred under high temperature and high temperature and high humidity conditions. In Comparative Example 4, the cohesive force of the adhesive was weak because the gel fraction of the adhesive was low, and foaming occurred under high temperature and high temperature and high humidity conditions. In Comparative Examples 5, 6 and 8, since the polymer component having a molecular weight of 10,000 or less in the sol content is small, light leakage occurs under high temperature and high temperature and high humidity conditions. Also in Comparative Example 7, since the polymer component having a molecular weight of 10,000 or less in the sol content is small, light leakage occurs under high temperature conditions.

[0057]

INDUSTRIAL APPLICABILITY As described above, the pressure-sensitive adhesive for optical members of the present invention and the optical member of the present invention using the pressure-sensitive adhesive for optical members are the stress of the pressure-sensitive adhesive layer under high temperature or high temperature and high humidity conditions. Due to its excellent relaxation property, peeling, foaming, light leakage, and frame phenomenon can be significantly suppressed under high temperature and high temperature and high humidity atmosphere. In particular, as shown in the examples, the effect is remarkable when the attachment area is large.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 510 G02F 1/1335 510 1/13363 1/13363 F term (reference) 2H049 BA02 BA04 BA06 BB51 2H091 FA08X FA08Z FA11X FB02 FB12 GA16 GA17 LA02 LA17 4J004 AA10 AA13 AA14 AB05 CA04 CA06 CB03 CC02 FA01 FA04 4J040 DF041 DF051 EF111 EF131 EF231 EF251 EF301 GA05 GA07 GA11 GA14 GA22 GA29 HB44 NA16 MA10 HD30 HC29 HC22 HD

Claims (6)

[Claims] 1. A pressure-sensitive adhesive comprising a polymer having a (meth) acrylic acid ester as a main component, an antioxidant and a crosslinking agent, wherein the pressure-sensitive adhesive has a gel fraction of 30 to 60%. A pressure-sensitive adhesive for an optical film, wherein a polymer component having a molecular weight of 10,000 or less measured by GPC in the sol portion of the agent is 25% by weight or more in the sol portion. 2. The pressure-sensitive adhesive for an optical film according to claim 1, wherein the antioxidant is a phenolic compound. 3. The pressure-sensitive adhesive for optical films according to claim 1, wherein the crosslinking agent is an isocyanate compound, an epoxy compound, or an aziridine compound. 4. The pressure-sensitive adhesive for an optical film according to claim 1, wherein the pressure-sensitive adhesive is further mixed with a silane coupling agent. 5. An optical film having a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive according to any one of claims 1 to 4 on one side or both sides of a support. 6. The optical film according to claim 5, wherein the support is a polarizing film, a retardation film or an elliptically polarizing film.