JPH08120238A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE: To obtain a pressure-sensitive adhesive composition excellent in durability by mixing an acrylic resin with a curing agent, a silane compound represented by a specified formula and an epoxy alcohol. CONSTITUTION: A monomer (e.g. n-butyl acrylate) is copolymerized with a comonomer (e.g. acrylic acid) in the presence of a polymerization initiator in a solvent (e.g. toluene) to prepare an acrylic copolymer solution. This solution is mixed with 0.01-10 pts.wt., per 100 pts.wt. solid matter of the solution, curing agent comprising an isocyanate compound (e.g. tolylene diisocyanate), 0.0001-10 pts.wt. silane compound represented by formula I (R1 to R4 are each 1-24C alkyl or alkoxy) (e.g. tetramethoxysilane), 0.0001-10 pts.wt. epoxy alcohol represented by formula II (n is 1-20) (e.g. γ-glycidoxypropanol) and a curing aid comprising a polyol compound and/or a melamine compound to obtain a pressure-sensitive adhesive composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel pressure-sensitive adhesive composition which has a small change in cohesive force and adhesive force with time even under high temperature or high temperature and high humidity and is excellent in curved surface adhesive force. In particular, the present invention relates to a pressure-sensitive adhesive composition suitable for adhering an optical film and a substrate.

[0002]

2. Description of the Related Art Generally, conventionally used pressure-sensitive adhesive compositions or their applied products such as pressure-sensitive adhesive tapes and pressure-sensitive adhesive sheets can be adhered to various surfaces of an application body at room temperature under a pressure of about finger pressure. Is used for. However, when the composition or its applied article is exposed to high temperature or high temperature and high humidity conditions after being adhered to the adherend surface, it has a drawback of peeling from the adherend surface, and its application is also restricted. It is the actual situation.

In order to solve these problems, a pressure-sensitive adhesive composition exhibiting adhesiveness that can be used even under conditions of high temperature, high humidity, or water, for example, vinyl silane, epoxy silane, methacryl silane is added to an acrylic polymer. A pressure-sensitive adhesive composition containing at least one selected from the group (Japanese Patent Publication No. 62-30233), and an adhesive containing an epoxy group-containing silane compound in an acrylic resin having a hydroxyl group capable of reacting with an epoxy group. Composition (JP-A-61-7)
369), a pressure-sensitive adhesive composition obtained by blending an isocyanate group-containing organosilicon compound with an acrylic resin copolymerized with an ethylenically unsaturated monomer capable of reacting with an isocyanate group (JP-A-1-158080). Proposed.

[0004]

However, in the technique disclosed in Japanese Patent Publication No. 62-30233, the bonding strength between the acrylic polymer and the silane compound is weak, so that the improvement of the adhesive strength is small and the cohesive strength is small. It is still unsatisfactory in terms of obtaining a pressure-sensitive adhesive composition whose change with time is small. Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 61-7369, the reaction between the glycidyl group and the hydroxyl group-containing acrylic resin is slow, and it is difficult to cure at room temperature. When a catalyst is used, water resistance and moisture resistance are extremely reduced.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 1-158087, although the above-mentioned room temperature curability is improved, a pressure-sensitive adhesive composition which does not deteriorate in water resistance and humidity resistance with time is obtained. An adherend with a curved surface that requires adhesive strength,
For example, the adhesive performance to a curved surface portion of a film type liquid crystal or a liquid crystal display body having a curved surface in a label application or an optical application (adhesive application between an optical film and a glass substrate) in which a curved surface is selected as an adherend is described in the above publication. Including the above, no consideration is given, and the application of the pressure-sensitive adhesive composition is also restricted. As a result of a detailed study by the present inventors on this point, in consideration of diversification of pressure-sensitive adhesive applications, sufficient adhesiveness cannot be obtained by the above-mentioned technique, and a sufficiently satisfactory pressure-sensitive adhesive composition can be obtained. There is still room for improvement.

On the basis of the above background, therefore, there is little change in cohesive force and adhesive force with time even under high temperature or high temperature and high humidity, and a curved surface is selected as an adherend or a film type liquid crystal having a curved surface or It is desired to develop a pressure-sensitive adhesive composition that is excellent in the adhesive force (curved surface adhesive force) to an adherend having a curved surface such as a liquid crystal display. In particular, polarizing plate, retardation plate,
In optical applications such as elliptically polarizing plates, the application frequency thereof is high, and such adhesive compositions can be greatly utilized.

[0007]

However, as a result of intensive studies to solve the above problems, the present inventors have found that a curing agent, a silane compound represented by Chemical Formula 1 and an epoxy group are contained in an acrylic resin. The present invention has been completed by finding out that the pressure-sensitive adhesive composition containing the alcohol having the above-mentioned can solve the above-mentioned problems.

Embedded image Here, R ₁ , R ₂ , R ₃ and R ₄ are alkyl groups having 1 to 20 carbon atoms and alkoxyl groups (provided that at least one of R ₁ , R ₂ , R ₃ and R ₄ is an alkoxyl group). is there.

The greatest feature of the present invention is that a curing agent, particularly an isocyanate compound, and the above silane compound and an alcohol having an epoxy group are mixed in an acrylic resin, and particularly as an alcohol having the epoxy group. When the compound represented by the following chemical formula 2 is used, it exhibits remarkably excellent cohesive strength, adhesive strength or curved surface adhesive strength with little change over time even at high temperature or under high temperature and high humidity.

Embedded image Here, n is an integer of 1 to 20.

Further, in the present invention, when a polyol compound and / or a melamine compound is used in combination as a curing aid in addition to the curing agent and blended, the particularly excellent effect of the present invention is exhibited. Further, the pressure-sensitive adhesive composition of the present invention is used for adhesion to a glass substrate in optical applications such as a polarizing film and a retardation film to provide an optical laminate having excellent durability and small change in optical properties. You can

The present invention will be specifically described below.
Examples of the constituent component of the acrylic resin of the present invention include a soft monomer component having a low glass transition temperature, a hard comonomer component having a high glass transition temperature, and a small amount of a functional group-containing monomer component.

As the main monomer component, the number of carbon atoms of the alkyl group such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, cyclohexyl acrylate is 2 To about 12 acrylic acid alkyl esters, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, and other methacrylic acids having 4 to 12 carbon atoms. Examples of the comonomer component include alkyl acrylates and the like, and alkyl methacrylates such as methyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate having 1 to 3 carbon atoms of alkyl groups, and vinyl acetate. , Acrylonitrile, methacrylonitrile, styrene, and the like. Further, a monomer generally used in the synthesis of acrylic resins such as an acrylic acid alkyl ester or a methacrylic acid alkyl ester in which an alkyl group is substituted with an aromatic ring group, a heterocyclic group, a halogen atom or the like is used as a pressure sensitive adhesive of the present invention. It can also be used for the synthesis of resin.

In addition to the above, the functional group-containing monomer component is, for example, a carboxyl group-containing monomer such as a monocarboxylic acid such as acrylic acid, methacrylic acid or crotonic acid,
There are polyvalent carboxylic acids such as maleic acid, fumaric acid, citraconic acid, glutaconic acid and itaconic acid, and anhydrides thereof, and the like.
Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono ( Examples thereof include (meth) acrylate, N-methylol acrylamide, and allyl alcohol.

Further, as the tertiary amino group-containing monomer,
There are dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, etc., amide group, N
-As the substituted amide group-containing monomer, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N- Butoxymethyl (meth) acrylamide, N-tert-butyl acrylamide, N-octyl acrylamide, diacetone acrylamide and the like. Examples of the nitrile group-containing monomer include acrylonitrile, methacrylonitrile, crotononitrile, fumaronitrile and the like. In addition, phosphoric acid-based acrylate and the like are also included.

Among the functional group-containing monomer components,
It is particularly preferable to use a carboxyl group-containing monomer. The content of the main monomer component cannot be unconditionally specified depending on the type and content of the other comonomer component or functional group-containing monomer component to be contained, but generally, the main monomer may be contained in an amount of 50% by weight or more. preferable. Further, it is desired that the content of the functional group-containing monomer component is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, and more preferably 0.01 to 25% by weight. The acrylic resin of the present invention is easily produced by a method well known to those skilled in the art, such as radical copolymerization of a main monomer, a comonomer, and a functional group-containing monomer in an organic solvent.

The organic solvent used for the above polymerization is
Aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and iso-propyl alcohol, ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone Etc. Specific examples of the polymerization catalyst used in the radical polymerization include azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide and the like which are ordinary radical polymerization catalysts.

In the present invention, as described above, the acrylic resin is mixed with the curing agent, the silane compound represented by the chemical formula 1 and the alcohol having an epoxy group. The curing agent is not particularly limited, but is exemplified by isocyanate compounds, epoxy compounds, aldehyde compounds, amine compounds, metal salts, metal alkoxides, metal chelate compounds, ammonium salts and hydrazine compounds. .

Among the curing agents, the isocyanate compounds include tolylene diisocyanate, hydrogenated tolylene diisocyanate, tolylene diisocyanate adduct of trimethylol propane, xylylene diisocyanate adduct of trimethylol propane, triphenyl methane triisocyanate, methylene bis (4 -Phenylmethane) triisocyanate, isophorone diisocyanate and the like, and ketoxime block products, phenol block products and isocyanurates thereof are mentioned.

Examples of the epoxy compound include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di- or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane. Triglycidyl ether, diglycidyl aniline, diglycidyl amine,
N, N, N ', N'-tetraglycidyl m-xylenediamine, 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane and the like can be mentioned.

Examples of aldehyde compounds include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like. As the amine compound, hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin,
Melamine resin etc. are mentioned.

As the metal salt, aluminum, iron, copper,
Salts of polyvalent metals such as zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium, etc., such as chlorides, bromides, nitrates, sulfates, acetates, etc., such as cupric chloride, aluminum chloride, and chloride chloride. Examples thereof include ferric iron, stannic chloride, zinc chloride, nickel chloride, magnesium chloride, aluminum sulfate, copper acetate and chromium acetate. Examples of metal alkoxides include tetraethyl titanate, tetraethyl zirconate, and aluminum isopropionate.

Examples of the metal chelate compound include acetylacetone and acetoacetate ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. . As an ammonium salt,
Examples thereof include ammonium chloride, ammonium sulfate, ammonium acetate, ammonium propionate and the like. Examples of the hydrazine compound include hydrazine, hydrazine hydrate, and their inorganic salts such as base salts, sulfates and phosphates, and organic acid salts such as formic acid and oxalic acid.

In the present invention, of the above-mentioned curing agents, isocyanate compounds are preferable, and among them, tolylene diisocyanate adduct of trimethylolpropane is most effective. The amount of the curing agent added is 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic resin,
Preferably 0.1 to 7 parts by weight, more preferably 0.3 to
5 parts by weight. If the addition amount is less than 0.01 parts by weight, the curing will not be sufficient and will be unsatisfactory under high temperature conditions, while if it exceeds 10 parts by weight, the curing will be promoted too much and the adhesive force will decrease, which is not preferable.

The silane-based compound represented by the above chemical formula 1 is not particularly limited, and includes tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, etc. Among them, tetramethoxysilane, methyltrimethoxysilane, tetraethoxysilane, and methyltriethoxysilane are particularly preferable. On the other hand, the alcohol having an epoxy group is not particularly limited and is a linear epoxy alcohol or a cyclic epoxy. The number of functional groups such as an epoxy group and a hydroxyl group is not particularly limited, and is preferably a compound represented by the above chemical formula 2, specifically, γ
-Glycidoxymethanol, γ-glycidoxyethanol, γ-glycidoxypropanol, γ-glycidoxybutanol, γ-glycidoxypentanol, 3,4-
Examples thereof include epoxycyclohexylmethanol, 3,4-epoxycyclohexylethanol, 3,4-epoxycyclohexylpropanol, 3,4-epoxycyclohexylbutanol, and 3,4-epoxycyclohexylpentanol. Among them, γ-glycidoxymethanol, γ-glycidoxyethanol, γ-glycidoxypropanol, γ-glycidoxybutanol and γ-glycidoxypentanol are particularly preferable.

In the present invention, it is possible to use the above various silane compounds alone or in combination, or to use the various epoxy group-containing alcohols alone or in combination.
Particularly preferred as a combination of the silane compound and an alcohol having an epoxy group, tetramethoxysilane and γ-glycidoxypropanol, methyltrimethoxysilane and γ-glycidoxyethanol, tetraethoxysilane and γ-glycid. Xybutanol and the like.

In the present invention, an acrylic silane, a mercapto silane, a silane,
It is also possible to use other silane compounds such as hydroxyl group silane together.

The amount of the silane compound added is 0.0001 with respect to 100 parts by weight of the acrylic resin.
-10 parts by weight, preferably 0.0005 to 7 parts by weight, more preferably 0.001 to 5 parts by weight. If the addition amount is less than 0.0001 parts by weight, the effect of addition cannot be obtained and 10 parts by weight. If it exceeds the range, the cohesive force decreases, and the excellent adhesive force and cohesive force of the present invention are not exhibited.

The amount of the alcohol having an epoxy group added is 0.0001 to 10 parts by weight, preferably 0.0005 to 5 parts by weight, based on 100 parts by weight of the acrylic resin.
It is 7 parts by weight, more preferably 0.001 to 5 parts by weight. If the addition amount is less than 0.0001 parts by weight, the effect of the addition cannot be obtained, and if it exceeds 10 parts by weight, the cohesive force decreases, which is not preferable.

In the present invention, in addition to the curing agent, it is preferable to blend one or more polyol compounds and melamine compounds as a curing aid. With respect to the blending amount, 0.001 to 50 parts by weight, preferably 0.01 to 30 parts by weight in the case of a polyol compound, and 0.001 to 0.001 in the case of a melamine compound, relative to 100 parts by weight of the acrylic resin. 10 parts by weight, preferably 0.001
It is preferable to add 0.5 parts by weight, and the effect of the present invention can be remarkably exhibited.

The polyol-based compound is not particularly limited, and polyether polyol, polyester polyol, hydroxyl group-containing polybutadiene polyol,
Acrylic polyols, castor oil derivatives, tall oil derivatives, and other nitrogen-free polyols are mentioned, and among them, trimethylolpropane, 1,4-butanediol, polytetramethylene ether glycol,
Examples thereof include ethylene glycol, propylene glycol, 3-methylpentane-1,3,5-triol, and the like. Preferable examples include nitrogen-containing polyol compounds represented by the following Chemical Formulas 3 and 5. Specific examples thereof include triethanolamine, methyldiethanolamine, polyoxyethylenestearylamine and polyoxyethylenelaurylamine, preferably methyldiethanolamine and polyoxyethylenestearylamine. Chemical formula 5 includes N, N, N ′. , N′-tetrakis (2-hydroxypropyl) ethylenediamine,
Adeka quadrol (Asahi Denka Kogyo Co., Ltd.) can be mentioned.

[0030]

Embedded image Here, R and R ′ are alkyl groups, R ₁ is hydrogen, an alkyl group, an acyl group, a phenyl group, or one of the following chemical formulas 4, and m, n, k, and l are integers of 0 or more (provided that , M and n, and k and l do not become 0 at the same time.).

[Chemical 4]

[0031]

Embedded image Here, R and R'are alkyl groups, X is an alkylene group or a phenylene group, and a, b, m, n, k, l, x and y are integers of 0 or more (provided that a, b, m and n, k and l, x and y
Neither becomes 0 at the same time. ) And p is an integer of 1 or more.

The melamine compound is not particularly limited, but a compound represented by the following chemical formula 6 is preferable. Specifically, R ₂ is hydrogen (9% by weight), —CH ₂ OH (31% by weight), Super Beckamine J-820-60 (Dainippon Ink and Chemicals, Inc.) consisting of —CH ₂ OBu (60% by weight) can be mentioned.

[0033]

[Chemical 6] Here, R ₂ is hydrogen or —CH ₂ —O—R ₂ ′ (however,
R ₂ ′ is hydrogen or an alkyl group), R ₃ is R ₂ or a bond formed by condensation, and r is an integer of 1 or more.

The method of blending the acrylic resin, the curing agent, the curing aid, the silane compound represented by Chemical formula 1 and the alcohol having an epoxy group is not particularly limited, and the batch charging or the acrylic resin, Curing agent, curing aid,
A plurality of silane compounds and alcohols having an epoxy group may be mixed in advance and the remaining components may be mixed later.

Thus, the pressure-sensitive adhesive composition of the present invention has a small change in cohesive force and adhesive force with time even under high temperature or high temperature and high humidity, and has an excellent effect on the curved adhesive force peculiar to the present invention. It is an agent composition. Regarding the use of such a pressure-sensitive adhesive composition, after being dissolved in an organic solvent such as toluene, ethyl acetate, methyl ethyl ketone, or acetone, it is applied to a substrate or a film such as a release film, and then 30 to 170.
It is dried and cured at a drying temperature of C, preferably 40-150 C, to obtain its tacky properties.

The adhesive composition is an adhesive tape,
It is effectively used for various adhesive applications such as an adhesive sheet, and is further laminated to various base materials. The base material is not particularly limited, but metal plates of all materials including stainless steel plate, aluminum plate, steel plate, copper plate, synthetic resin decorative plate such as polyethylene plate, polypropylene plate, melamine plate, phenol plate, plywood, and veneer. In addition to what is called a plate-shaped object such as a glass plate, it can be attached to the surface of a rod-shaped object, pottery or various molded products.

Further, the pressure-sensitive adhesive composition of the present invention exhibits a very excellent effect in bonding a substrate, particularly a glass substrate, to an optical film. That is, by using the pressure-sensitive adhesive composition, when used in a high temperature or high temperature and high humidity environment, appearance defects such as foaming and peeling of the pressure-sensitive adhesive layer do not occur, and heat resistance and wet heat resistance are excellent, and further, optical An optical laminate having excellent characteristics can be obtained.

The optical film used in the present invention is not particularly limited as long as it has optical characteristics.
It is preferable to use a polarizing film, a retardation film, an elliptically polarizing film, or the like, and by using the pressure-sensitive adhesive composition of the present invention for bonding these optical films and a glass substrate, heat resistance, moisture heat resistance and optical characteristics are excellent. Thus, an optical laminate of film / glass substrate can be obtained. In the present invention, a protective layer is mainly provided on an optical film such as a polarizing film, a retardation film, and an elliptical polarizing film, but unless otherwise specified, it is referred to as an optical film with or without a protective layer.

The optical laminate will be described in detail below. In the present invention, for example, mainly a polyvinyl alcohol-based polarizing film as a substrate, a polarizing plate provided with a protective layer if necessary, or a polyvinyl alcohol-based or polycarbonate-based retardation film as a substrate, which is necessary for this. Accordingly, the pressure-sensitive adhesive layer and the release film are added to a retardation plate provided with a protective layer, an elliptically polarizing plate in which a polarizing film and a retardation film are combined, and the like. As a method for adding the pressure-sensitive adhesive layer and the release film, the pressure-sensitive adhesive layer is provided on the release film, and the optical film is attached thereon, or vice versa. The method of sticking a release film on is usually adopted.

The optical film having the pressure-sensitive adhesive layer thus obtained is appropriately cut at the time of use, the release film is peeled off, and it is bonded to a glass or other base material which is a mating base material, and then the Used for glare or sunglasses. Further, the optical film having the pressure-sensitive adhesive layer is used for a reflective or semi-transmissive liquid crystal display panel by further providing a reflective plate and / or a translucent layer. This reflector is usually made of aluminum, silver or other foil,
Boards are used. Further, as the semitransparent layer, the reflectance and the transmittance are selected so that both of the reflection type and the transmission type can be used, and the material is appropriately selected.

The retardation film is not particularly limited and includes polyvinyl alcohol, polycarbonate, polyester, polyarylate, polyimide, polyolefin, polystyrene, polysulfone, polyether sulfone, polyvinylidene fluoride / polymethylmethacrylate, liquid crystal polymer. , Triacetyl cellulose resin, cyclic polyolefin, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride and the like are used, but mainly polycarbonate and polyvinyl alcohol resin film are used. Polyvinyl alcohol-based resins are usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. However, a small amount of unsaturated carboxylic acids (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, It may contain a component which is copolymerizable with vinyl acetate, such as a saturated sulfonate. Also, polyvinyl alcohol was reacted with aldehydes in the presence of acid,
Examples thereof include so-called polyvinyl acetal resins such as polybutyral resins and polyvinyl formal resins, and polyvinyl alcohol derivatives. Average degree of polymerization is 500-
10,000, the saponification degree is 80 to 100 mol%,
It is preferably uniaxially stretched about 1.01 to 4 times.

On the other hand, the polarizing film has an average degree of polymerization of 15
00 to 10000, saponification degree 85 to 100 mol% of the above polyvinyl alcohol resin as a raw film,
A uniaxially stretched film dyed with an aqueous solution of iodine-potassium iodide or a dichroic dye (a draw ratio of 2 to 10 times, preferably about 3 to 7 times) is used.

Examples of the protective layer include conventionally known cellulose acetate type films, acrylic type films, polyester type resin films, polyolefin type resin films, polycarbonate type films, polyether ether ketone type films, polysulfone type films and the like. However, a cellulose acetate film such as a cellulose triacetate film is preferably used. Further, if necessary, it is possible to blend an ultraviolet absorber such as a salicylic acid ester-based compound, a benzophenol-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, or a nickel complex salt-based compound into the resin film.

[0044]

The pressure-sensitive adhesive composition of the present invention is used as a curing agent, particularly an isocyanate compound, an silane compound represented by the above chemical formula 1 and an alcohol having an epoxy group in an acrylic resin, and more preferably as a curing aid. Since a polyol-based compound and / or a melamine-based compound is blended, the cohesive force and the adhesive force have little change with time even under high temperature or high temperature and high humidity, and also have an excellent effect on curved surface adhesive force. When used for adhesion of optical film and base material, it not only has excellent durability such as foaming and peeling of the adhesive, but also its optical characteristics deteriorate even when left for a long time under high temperature and high humidity environment. It also has the effect of not doing it. Utilizing such characteristics, it is used for liquid crystal displays, and is particularly useful for vehicles, various industrial instruments, and displays of household electric appliances.

[0045]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, "part" and "%" are based on weight unless otherwise specified. Example 1 100 parts of a mixture of n-butyl acrylate: acrylic acid = 95: 5 (weight ratio), 0.1 part of benzoyl peroxide as a polymerization initiator was added, and the mixture was polymerized in toluene to obtain a copolymer. A solution was obtained. In the copolymer solution, 1 part of Coronate L (manufactured by Nippon Polyurethane Company) as an isocyanate compound, 1 part of tetramethoxysilane, 1 part of γ-glycidoxy propanol, relative to 100 parts of solid content of the copolymer solution. Was added and mixed well to obtain an adhesive composition. With respect to the obtained pressure-sensitive adhesive composition, the adhesive strength, cohesive strength and curved surface adhesive strength were evaluated. The evaluation methods of the adhesive force, cohesive force and curved surface adhesive force are as shown below.

(Adhesive Strength) After dissolving the above-mentioned pressure-sensitive adhesive composition in toluene, it is applied to a polyethylene terephthalate film and dried at 100 ° C. for 2 minutes (application amount after drying 25 μm.
m) and reciprocate it three times with a manual roller according to JIS Z 0237 (size: width 25 mm, length 1
It was crimped to 80 mm). The sample was autoclaved (50 ° C., 15 minutes, 5 kg / cm ² ), and kept at 60 ° C. for 1 hour.
After heat treatment for 2 hours and leaving it under the condition of 20 ° C. and 65% RH for 1 hour, using an apparatus according to JIS B 7721,
The adhesive strength (kg / 25 mm) was measured by the 90-degree pulling method according to JIS Z 0237. The pulling rate was 200 mm / min.

(Cohesive Strength) A polyethylene terephthalate film (size: coated with an adhesive composition in the same manner as above)
A glass plate (size: width 40 mm, length 80 mm) having a width of 25 mm and a length of 150 mm was crimped back and forth three times by a manual roller according to JIS Z 0237. The sample is autoclaved (50 ° C., 15 minutes, 5 kg / cm ² ).
Then, after leaving it for 1 hour under the condition of 20 ° C. and 65% RH,
A load of 1 kg is applied to the end, and measurement is performed according to JIS Z 0237, and the size of deviation (m
m) was measured and evaluated according to the following criteria. A: Less than 0 to 0.5 (mm) O: Less than 0.5 to 5.0 (mm) B: Less than 5.0 to 10.0 (mm) X: 10.0 (Mm) or more

(Curved surface adhesive strength) A test piece similar to the above with a width of 25 mm and a length of 66 mm was attached to the curved surface of a glass cylinder having a diameter of 30 mmφ using the weight of the cylinder (200 g), and then autoclaved (50 ° C., 15 ° C.). Min, 5 kg / cm ² )
Then, leave it at 40 ° C for 24 hours, then 40 ° C, 95% RH.
Size of peeling after leaving for 24 hours under the condition (mm)
It was evaluated by. A: Less than 0 to 0.5 (mm) O: Less than 0.5 to 5.0 (mm) B: Less than 5.0 to 10.0 (mm) X: 10.0 (Mm) or more

Further, the obtained pressure-sensitive adhesive composition has a thickness of 1.1 m.
m on a glass plate using an applicator so that the thickness after drying is 25 μm, and dried at 100 ° C. for 2 minutes to obtain an adhesive plate, while a polyvinyl alcohol polarizing film having a thickness of 30 μm (average degree of polymerization) 1700, average saponification degree 99 mol%, 4 times stretched) A polarizing plate in which cellulose triacetate film having a thickness of 80 μm was laminated on both sides (the stretching axis direction of the polyvinyl alcohol polarizing film was inclined at 45 degrees,
(Cut to 0 mm × 200 mm) was prepared, the above-mentioned adhesive plate was laminated on one side thereof, and pressed with a roller to manufacture a glass laminated polarizing plate. The polarizing plate was tested for heat resistance (90 ° C., 500 hours) and humidity heat resistance (60 ° C. × 90% RH, 500 hours) to evaluate changes in appearance and changes in optical characteristics.

Regarding the optical characteristics of the polarizing plate, the single-piece transmittance τ (%) and the degree of polarization V (%) were measured. Here, the degree of polarization in the present invention is represented by [(H ₁₁ −H ₁ ) / (H ₁₁ + H ₁ )] ^1/2 × 100 (%), and H ₁₁ is the superposition of two polarizing film samples. In some cases, the transmittance (%) measured with a spectrophotometer in a state where the polarizing films are superposed so that the orientation directions thereof are the same, H ₁ is a value of the polarizing film when the two samples are superposed. It is the transmittance (%) measured in a state in which the alignment directions are orthogonal to each other and the layers are superposed.

Similarly, a retardation film (average degree of polymerization: 170
0, average saponification degree 97 mol%, 1.1 times stretched polyvinyl alcohol film, film thickness 50 μm), a retardation plate (polyvinyl alcohol) having a 80 μm thick cellulose triacetate film laminated on both sides of the retardation film. 150 mm x 200 with the film stretching axis tilted 45 degrees
(cut to mm) was prepared, the above-mentioned adhesive plate was laminated on one side thereof, and pressed with a roller to manufacture a glass laminated retardation plate. The retardation plate was subjected to heat resistance (70 ° C., 500 hours) and humidity heat resistance (40 ° C. × 95% RH, 500 hours) test to evaluate changes in appearance and changes in optical characteristics.

Regarding the optical characteristics of the retardation plate, the retardation value (RD) was measured. The retardation value (RD) of the retardation film means the main stretching direction (M
It is defined by the product of the refractive index (II _MD- II _TD ) in the direction (D direction) and the direction (TD direction) perpendicular thereto and the thickness (d) of the retardation film, and is a polarizing microscope with a Babinet type compensator (Nikon It was measured by a compensation method using POH-1 type (light source is white light).

Further, an elliptically polarizing plate having a constitution of cellulose triacetate film / polarizing film / cellulose triacetate film / adhesive layer / cellulose triacetate film / retardation film / cellulose triacetate film / adhesive layer Heat resistance (70 ° C, 500 hours), Moisture resistance (4
(0 ° C. × 95% RH, 500 hours) test was performed to evaluate appearance change.

The evaluation criteria are as follows. (Change in Appearance) After the durability test, the occurrence of foaming and peeling of the pressure-sensitive adhesive was visually observed. No change ・ ・ ・ ○ Foaming, peeling ... × (Optical property change) The polarizing plate was evaluated by the difference between the single transmittance τ (%) and the polarization degree V (%) before and after the durability test. It is desired that the absolute value is 5% or less. The retardation plate was evaluated by the difference in RD value before and after the durability test. It is desired that the absolute value is 30 nm or less.

Example 2 An adhesive composition obtained in the same manner as in Example 1 except that tetramethoxysilane was replaced with methyltrimethoxysilane and γ-glycidoxypropanol was replaced with γ-glycidoxyethanol. The adhesive strength, cohesive strength and curved surface adhesive strength of the product were evaluated in the same manner as in Example 1. A polarizing plate obtained by using the adhesive composition in the same manner as in Example 1,
With respect to the retardation plate and the elliptically polarizing plate, changes in appearance and changes in optical characteristics were evaluated by the above methods.

Example 3 In Example 1, tetramethoxysilane was replaced with tetraethoxysilane, and γ-glycidoxypropanol was replaced with γ.
-Do the same except that glycidoxybutanol was replaced,
With respect to the obtained pressure-sensitive adhesive composition, the adhesive strength, cohesive strength and curved surface adhesive strength were evaluated in the same manner as in Example 1. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Example 4 The same procedure as in Example 1 was repeated except that Coronate L (manufactured by Nippon Polyurethane Company) was replaced with a mixture of coronate L and Coronate HL (manufactured by Nippon Polyurethane Company) (L: HL = 1: 1). Example 1 of the obtained pressure-sensitive adhesive composition
The adhesive strength, cohesive strength and curved surface adhesive strength were evaluated in the same manner as in.
Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Example 5 In Example 1, Coronate L (manufactured by Nippon Polyurethane Co.) was used as a melamine resin Super Beckamine J-820-6.
In the same manner as in Example 1, except that the value was changed to 0 (Dainippon Ink and Chemicals), the adhesive strength, cohesive strength and curved surface adhesive strength of the obtained pressure-sensitive adhesive composition were evaluated. A polarizing plate obtained by using the adhesive composition in the same manner as in Example 1,
With respect to the retardation plate and the elliptically polarizing plate, changes in appearance and changes in optical characteristics were evaluated by the above methods.

Example 6 The same procedure as in Example 1 was repeated except that 0.1 part of N-methyldiethanolamine was further added as a curing aid.
With respect to the obtained pressure-sensitive adhesive composition, the adhesive strength, cohesive strength and curved surface adhesive strength were evaluated in the same manner as in Example 1. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Example 7 The same procedure as in Example 1 was carried out except that 1.0 part of trimethylolpropane was added as a curing aid. The force and curved surface adhesion were evaluated. Further, a polarizing plate, a retardation plate, obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1,
With respect to the elliptically polarizing plate, change in appearance and change in optical characteristics were evaluated by the above method.

Example 8 In Example 1, superbeckamine J-820-60 (Dainippon Ink and Chemicals) was further added as a curing aid.
The same procedure as in Example 1 was carried out except that 1 part was added, and the adhesive strength, cohesive strength and curved surface adhesive strength of the obtained pressure-sensitive adhesive composition were evaluated. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 1 In the same manner as in Example 1 except that tetramethoxysilane was not added, the adhesive composition obtained was evaluated for adhesive strength, cohesive strength and curved surface adhesive strength in the same manner as in Example 1. did. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 2 The same procedure as in Example 1 was carried out except that γ-glycidoxy propanol was not added, and the obtained adhesive composition was subjected to the same adhesive strength, cohesive strength and curved surface contact as in Example 1. The wearing power was evaluated. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 3 The procedure of Example 1 was repeated except that Coronate L (manufactured by Nippon Polyurethane Co., Ltd.) was not added. The curved surface adhesion was evaluated. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 4 The same procedure as in Example 1 was conducted except that 1.0 part of γ-glycidoxypropyltrimethoxysilane was added instead of the addition of tetramethoxysilane and γ-glycidoxypropanol. The pressure-sensitive adhesive composition thus obtained was evaluated for adhesive strength, cohesive strength and curved surface adhesive strength in the same manner as in Example 1. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 5 The same procedure as in Example 1 was carried out except that tetramethylsilane was used instead of tetramethoxysilane, and the obtained adhesive composition had the same adhesive strength, cohesive strength and curved surface adhesive strength as in Example 1. Was evaluated. Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods.

Comparative Example 6 To 100 parts of the acrylic copolymer of Example 1, 1.0 part of trimethoxysilanepropyl isocyanate was added to obtain a pressure-sensitive adhesive composition, and the obtained pressure-sensitive adhesive composition was used in Example 1
The adhesive strength, cohesive strength and curved surface adhesive strength were evaluated in the same manner as in.
Also, with respect to a polarizing plate, a retardation plate and an elliptically polarizing plate obtained by using the pressure-sensitive adhesive composition in the same manner as in Example 1, the change in appearance and the change in optical characteristics were evaluated by the above methods. Example,
The evaluation results of each of the comparative examples are summarized in Tables 1 to 4.

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[Table 1] Adhesive properties Adhesive strength Cohesive strength Curved adhesive strength (kg / 25 mm) Example 1 1.2 ○ ◎ 〃 2 1.0 ○ ◎ 〃 3 1.1 ○ ◎ 〃 4 1.1 ○ ◎ 〃 5 1 .1 ○ ◎ 〃 6 1.2 ◎ ◎ ◎ 7 1.2 1.2 ◎ ◎ 〃 8 1.2 ◎ ◎ Comparative Example 1 1.3 × × 〃 2 1.3 × × 〃 3 1.3 × △ 〃 4 1 .2 △ △ 5 1.2 × × 〃 6 1.0 × ×

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[Table 2] (Change in appearance) Polarizing plate Phase difference plate Elliptical polarizing plate Heat resistance Moisture heat resistance Heat resistance Moisture resistance Heat resistance Moisture resistance After test After test After test After test After test Example 1 ○ ○ ○ ○ ○ ○ 〃 2 ○ ○ ○ ○ ○ ○ 〃 3 ○ ○ ○ ○ ○ ○ 〃 4 ○ ○ ○ ○ ○ ○ 〃 5 ○ ○ ○ ○ ○ ○ 〃 6 ○ ○ ○ ○ ○ ○ 〃 7 ○ ○ ○ ○ ○ ○ 〃 8 ○ ○ ○ ○ ○ ○ Comparative Example 1 × × × × × × × 〃 2 × × × × × × × 〃 3 × × × × × × × 4 × × × × × × 5 × × × × × × × 〃 6 × × × × × ×

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[Table 3] (Optical properties) Heat resistance Heat resistance Moisture resistance Moisture resistanceBefore test After test Before test After test Example 1 Polarizing plate τ 40.0 40.5 40.0 41.0 V 99.9 99.9 99.9 99.8 Retardation plate RD 402 410 403 395 〃 2 Polarizing plate τ 39.8 40.2 39.9 41.0 V 99.9 99.9 99.9 99.9 99.7 Retardation plate RD 398 410 410 402 392 〃 3 Polarizing plate τ 40.1 40.3 40.2 40.9 V 99.9 99. 9 99.9 99.9 Retardation plate RD 403 409 400 390 〃 4 Polarizing plate τ 40.3 40.5 40.2 40.8 V 99.9 99.9 99.9 99.8 Retardation plate RD 405 409 398 389 〃 5 polarizing plate τ 40.0 40.5 40.0 41.0 V 99.9 99.9 99.9 99.8 retardation plate RD 402 410 403 395 〃 6 polarizing plate τ 39.8 40 .2 39.9 41.0 V 99.9 99.9 99.9 99.7 Retardation plate R 398 410 402 392 〃 7 Polarizer τ 40.1 40.3 40.2 40.9 V 99.9 99.9 99.9 99.8 Phase difference plate RD 403 409 400 390 〃 8 Polarizer τ 40.1 40.4 40.2 41.0 V 99.9 99.9 99.9 99.8Retardation plate RD 402 409 401 393  Note) τ: Single transmittance (%) V: Degree of polarization (%) RD: Retardation value (nm)

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[Table 4] (Optical properties) Heat resistance Heat resistance Moisture resistance Moisture resistance Before test After test Before test After test Comparative example 1 Polarizing plate τ − Unmeasurable − Unmeasurable V − 〃 − 〃 Phase difference plate RD − 〃 − 〃 〃 2 Polarized Plate τ − 〃 − 〃 V − 〃 − 〃 Phase difference plate RD − 〃 − 〃 〃 3 Polarizer τ − 〃 − 〃 V − 〃 − 〃 Phase RD − 〃 − 〃 〃 〃 〃 4 V - 〃 - 〃 retarder RD - 〃 - undefined undefined 5 polarizers tau - 〃 - 〃 V - 〃 - 〃 retarder RD - 〃 - undefined undefined 6 polarizer tau - 〃 - 〃 V - 〃 - 〃 position Phase difference plate RD-〃-〃 Note) τ: Single transmittance (%) V: Degree of polarization (%) RD: Retardation value (nm) In Comparative Examples 1 to 6, foaming and peeling were observed after the durability test. Since the optical characteristics could not be measured because it occurred, the measured values before the test were not written intentionally. .

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EFFECT OF THE INVENTION The pressure-sensitive adhesive composition of the present invention shows a small effect of cohesive force and adhesive force with time even under high temperature or high temperature and high humidity, and has an excellent effect on curved surface adhesive force. In adhesion of film and various substrates such as glass, not only is it excellent in durability such as foaming and peeling of the adhesive, but its optical characteristics deteriorate even when left in a high temperature and high humidity environment for a long time. It also has the effect of not doing it.

Claims (9)

[Claims] 1. A curing agent and a chemical compound in an acrylic resin.
A pressure-sensitive adhesive composition comprising a silane compound represented by the formula (1) and an alcohol having an epoxy group. Embedded image Here, R ₁ , R ₂ , R ₃ and R ₄ are alkyl groups having 1 to 20 carbon atoms and alkoxyl groups (provided that at least one of R ₁ , R ₂ , R ₃ and R ₄ is an alkoxyl group). is there. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the alcohol having an epoxy group is a compound represented by Chemical formula 2. Embedded image Here, n is an integer of 1 to 20. 3. The addition amount of the silane compound represented by Chemical formula 1 is 0.0001 to 100 parts by weight of the acrylic resin.
It is 10 weight part, The adhesive composition of Claim 1 or 2 characterized by the above-mentioned. 4. The amount of the alcohol having an epoxy group added is 0.0001 to 100 parts by weight of the acrylic resin.
It is 10 weight parts, Claim 1, 2 or 3 characterized by the above-mentioned.
The adhesive composition described. 5. The pressure-sensitive adhesive composition according to claim 1, wherein the curing agent is an isocyanate compound. 6. An acrylic resin 100 containing a curing agent
It is 0.01-10 weight part with respect to weight part, The adhesive composition in any one of Claims 1-5 characterized by the above-mentioned. 7. The pressure-sensitive adhesive according to claim 1, wherein the acrylic resin pressure-sensitive adhesive is further blended with a polyol compound or / and a melamine compound as a curing aid. Composition. 8. The pressure-sensitive adhesive composition according to claim 1, which is used for adhering a substrate and an optical film. 9. The pressure-sensitive adhesive composition according to claim 8, wherein the optical film is any one of a polarizing film, a retardation film and an elliptically polarizing film.