TW201817840A - Acrylic adhesive composition, adhesive obtained using same, polarizing plate adhesive, and image display device - Google Patents

Abstract

Provided is an acrylic adhesive composition with which it is possible to obtain an adhesive that exhibits excellent reworkability over a long period, and that does not undergo whitening due to heat and humidity even when exposed to a high-temperature, high-humidity environment, when used as an adhesive used for pasting together a polarizing plate (protective film) and a liquid crystal cell (glass) during the manufacturing of a liquid crystal display. The acrylic adhesive composition contains an acrylic resin (A) and a silane coupling agent (B), which contains at least one each of a reactive functional group and an alkoxy group in a structure, wherein the acrylic resin (A) contains 5-50 wt% of structural moieties derived from at least one polar group (a1) selected from a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer, and the silane coupling agent (B) contains an olygomer-type silane coupling agent (B1) in which the alkoxy group content is not more than 15 wt%.

Description

Acrylic adhesive composition, adhesive using the acrylic adhesive composition, adhesive for polarizing plate, and image display device

The present invention relates to an acrylic adhesive composition, an adhesive obtained by using the acrylic adhesive composition, and an adhesive for polarizing plates. More specifically, the present invention relates to an excellent long-term display performance. Acrylic adhesive composition which is heavy-duty, and is not easily affected by moisture, and does not cause deterioration in durability.

Conventionally, a polarizing plate is obtained by covering both surfaces of a polarizing plate made of a polyvinyl alcohol-based film or the like having a polarizing property with a protective film, and sandwiching a liquid crystal component aligned between two glass plates. A polarizing plate is laminated on the surface, and an image display device is manufactured. The lamination of the surface of the liquid crystal cell by the polarizing plate is usually carried out by abutting the adhesive layer provided on the surface of the polarizing plate to the liquid crystal cell surface and pressing it.

In order to adhere the protective film to a polarizer, an adhesive containing a polyvinyl alcohol-based resin is preferably used. Specifically, it is an aqueous solution obtained by blending a polyvinyl alcohol-based resin with a crosslinking agent. The polarizer is coated on a polarizer and a protective film is laminated, and then heated and dried to produce a polarizing plate. In the manufacturing steps of the above-mentioned polarizing plate, it is better that the moisture contained in the adhesive penetrates the protective film. The protective film has hitherto used triacetyl cellulose film (TAC film) with high moisture permeability. However, in recent years, consideration has been given to From the viewpoints of dimensional stability and durability, TAC films are gradually replaced with olefin-based films, especially cycloolefin-based films (COP films) as protective films for polarizing plates.

An adhesive for bonding such a polarizing plate to a liquid crystal cell (glass substrate) requires durability such as heat resistance and humidity and heat resistance. Especially in a high-temperature and high-humidity environment, moisture penetrates into the adhesive layer and the adhesion with the glass substrate is reduced, and there is a problem that the polarizing plate partially floats or peels off from the glass substrate. In order to solve such a problem, it is generally known to improve the humidity and heat resistance by mixing a silane coupling agent with an adhesive. However, when a silane coupling agent is mixed, the silane coupling agent reacts slowly and causes adhesion. The problem of increased power and reduced long-term reworkability.

In addition, when a cycloolefin-based film is used as a protective film for a polarizing plate, if exposed to a humid and hot environment, the problem of whitening of the adhesive layer may occur due to dew condensation when returning to normal temperature (wet and whitening phenomenon). In addition, conventionally used adhesives for polarizing plates have been used in accordance with the types of polarizing plates. However, considering cost and workability, it is desirable to have adhesives that can be used even if the types of polarizing plates are different.

Such an adhesive having excellent reworkability and moist heat whitening resistance, for example, Patent Document 1 discloses an adhesive composition containing 100 parts by weight of an adhesive resin (A) and an epoxy equivalent of 100 to 2000 g / mol. In addition, the polysiloxane oligomer (B) having an alkoxy content of 5 to 60% by weight is 0.1 to 20 parts by weight. The aforementioned adhesive resin (A) is selected from monomers containing no carboxyl group. One or more of the group consisting of an acrylic adhesive resin (A1), a urethane adhesive resin (A2), and a polyester adhesive resin (A3) obtained by polymerization. In addition, Patent Document 2 discloses an adhesive using an acrylic resin in which many polar group-containing monomers are introduced in consideration of moist-heat whitening resistance. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2016-44291 [Patent Document 2] Japanese Patent Application Publication No. 2013-213203

(Problems to be Solved by the Invention) However, the adhesive described in the above Patent Document 1 has loosely specified functional group equivalents and alkoxy content for the silane coupling agent (polysiloxyalkoxy oligomer) used. Various types of silane coupling agents can be used, but there is room for improvement in moist-heat whitening resistance when a protective film having low moisture permeability such as a cycloolefin-based film is used.

On the other hand, Patent Document 2 which considers moist heat and whitening resistance, describes that various optical members can be used, but because a lot of polar group-containing monomers are introduced into the acrylic resin, the hydrophilicity is enhanced. When TAC or acrylic film with high moisture permeability is used as the protective film, there is a problem that hydrolysis of the silane coupling agent is promoted and long-term reworkability is reduced.

Against this background, the present invention provides an acrylic adhesive composition, which can be used as an adhesive for bonding a polarizing plate (protective film) and a liquid crystal cell (glass) in the manufacture of a liquid crystal display device. An adhesive that exhibits excellent reworkability over a long period of time and does not cause whitening even when exposed to a high temperature and high humidity environment is obtained. (The way to solve the problem)

The inventors of this case worked hard on this matter, and found that by using an adhesive composition containing an acrylic resin and a silane coupling agent, the acrylic system containing a large number of structural units derived from a polar group-containing monomer will be included. A combination of a resin and an oligomeric type silane coupling agent with a low alkoxy content can be used to obtain an adhesive that exhibits excellent reworkability for a long period of time and does not cause whitening under high temperature and high humidity conditions.

That is, the first gist of the present invention is to provide an acrylic adhesive composition containing an acrylic resin (A), and a silane coupling agent having at least one reactive functional group and an alkoxy group in the structure ( B), characterized in that the acrylic resin (A) contains 5 to 50% by weight of at least one polar group selected from hydroxyl-containing monomers, carboxyl-containing monomers, and nitrogen-containing monomers. The silane coupling agent (B) contains an oligomeric silane coupling agent (B1) having an alkoxy content of 15% by weight or less. The second gist of the present invention is an adhesive made by crosslinking the acrylic adhesive composition of the first gist with the cross-linking agent (C), and the third gist is made by using the gluing agent of the second gist. The fourth gist of the adhesive for polarizing plates is an image display device in which the polarizing plate and the liquid crystal cell are bonded by the adhesive of the second gist. (Effect of the invention)

The invention is an acrylic adhesive composition containing an acrylic resin (A) and a silane coupling agent (B) having at least one reactive functional group and an alkoxy group in the structure, respectively. : The acrylic resin (A) contains 5 to 50% by weight of at least one polar group-containing monomer (a1) selected from a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer. ) Is an acrylic resin having a structural unit, and the silane coupling agent (B) contains an oligomeric silane coupling agent (B1) having an alkoxy content of 15% by weight or less. Therefore, the adhesive obtained by using the acrylic adhesive composition of the present invention is used as an adhesive for bonding a polarizing plate (protective film) and a liquid crystal cell (glass) when an image display device is manufactured. In this case, it is an adhesive that exhibits excellent reworkability for a long period of time, and has excellent moist-heat whitening resistance and durability, and is very useful as an adhesive for polarizing plates.

When the reactive functional group equivalent of the oligomeric silane coupling agent (B1) is 1,600 g / mol or less, durability is more excellent.

When the weight average molecular weight of the oligomeric silane coupling agent (B1) is 3,000 or more, the reworkability and durability are more excellent.

When the said polar group containing monomer (a1) contains a hydroxyl monomer at least, it is excellent in moist-heat whitening resistance.

The present invention is described in detail below. In the present invention, the (meth) acrylic group refers to an acrylic group or a methacrylic group, the (meth) acryl group refers to an acryl group or a methacryl group, and the (meth) acrylate refers to an acrylic group. Ester or methacrylate. The acrylic resin refers to a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

The acrylic adhesive composition of the present invention contains an acrylic resin (A) and a silane coupling agent (B) as essential components.

<Acrylic resin (A)> The acrylic resin (A) used in the present invention needs to be contained in an amount of 5 to 50% by weight from a monomer selected from a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer. The acrylic resin of the structural unit of at least one polar group-containing monomer (a1), for example, contains 5 to 50% by weight of a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer. An acrylic resin obtained by copolymerizing a copolymerization component of at least one polar group-containing monomer (a1) is preferred.

The copolymerization component of the acrylic resin (A) may contain an alkyl (meth) acrylate-based monomer (a2) and other copolymerizable ethylenically unsaturated monomers (a3) as necessary.

First, at least one polar group-containing monomer (a1) selected from a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer will be described.

The above hydroxyl-containing monomers are, for example, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxy (meth) acrylate. Hexyl esters, hydroxyalkyl acrylates such as 8-hydroxyoctyl (meth) acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, diethyl (meth) acrylate Hydroxyalkylene-modified monomers such as glycol esters and polyethylene glycol (meth) acrylates, and other examples include 2-propenyloxyethyl-2-hydroxyethyl phthalic acid, N-hydroxyl Mono-hydroxyl-containing monomers such as meth (meth) acrylamide, hydroxyethylacrylamide; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3- Mono-hydroxyl-containing monomers such as 2-hydroxypropyl chloro (meth) acrylate; 3-hydroxyl-containing monomers such as 2-hydroxyethyl 2,2-dimethyl (meth) acrylate.

Among the above-mentioned hydroxyl-containing monomers, from the viewpoint of excellent reactivity with a cross-linking agent and from the viewpoint of improvement of moist heat and whitening resistance, monomers containing a primary hydroxyl group are preferable, and from the viewpoint of stability during polymerization, (A 2-Hydroxyethyl acrylate is ideal, considering the reactivity of the cross-linking agent is fast, and the aging can be shortened. 4-hydroxybutyl (meth) acrylate is preferred. Furthermore, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, di (meth) acrylate, and the like have few impurities, and are considered to be easy to manufacture, which is preferable.

In addition, as the above-mentioned hydroxyl-containing monomer, it is preferable to use an impurity-containing di (meth) acrylate having a content ratio of 0.5% by weight or less, more preferably 0.2% by weight or less, and particularly preferably 0.1% by weight or less. Specifically, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxypropyl acrylate are preferable.

Examples of the carboxyl group-containing monomer include dimer acids of acrylic acid such as (meth) acrylic acid and β-carboxyethyl acrylic acid. Among them, the viewpoint of moist heat whitening resistance and the viewpoint of stability during polymerization are considered. (Meth) acrylic acid is preferred.

Examples of the nitrogen-containing monomer include an amine group-containing monomer and a fluorene amine group-containing monomer.

The above amine group-containing monomers include, for example, monomers containing a primary amine group such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate, and tert-butylaminoethyl (meth) acrylate Tertiary amine-containing monomers such as esters, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate Based monomers, etc. Among the above-mentioned amine group-containing monomers, a monomer containing a tertiary amine group is preferable from the viewpoint of a high crosslinking promotion effect and the viewpoint of storage stability of the resin solution. In addition, considering the viewpoint of excellent durability and the viewpoint of excellent adhesion to metals and metal oxides, (meth) acrylfluorenyl Heterocyclic amine monomers, such as phthaloline, are preferred. Especially preferred among these are dimethylaminoethyl (meth) acrylate and (meth) acrylfluorenyl Morpho.

Monoamine-containing monomers, for example: (meth) acrylamido; methoxymethyl (meth) acrylamido, ethoxymethyl (meth) acrylamido, propoxymethyl ( Meth) acrylamide, isopropoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, isobutoxymethyl (meth) acrylamide, etc. Oxyalkyl (meth) acrylamide-based monomers; dialkyl (meth) acrylamide-based monomers such as dimethyl (meth) acrylamine, diethyl (meth) acrylamine ; N- (hydroxymethyl) acrylamide and other hydroxyl-containing amidine monomers; (meth) acrylamide Porphyrin, etc. Among the above-mentioned amide-containing monomers, from the viewpoint of stability of the resin solution and the viewpoint of suppressing the movement of the antistatic agent, alkoxyalkyl (meth) acrylamidoamine-based monomers, dialkyl (methyl A) acrylamide-based monomer is preferred.

Among the above-mentioned polar group-containing monomers (a1), a monomer containing a hydroxyl group is preferably used from the viewpoint of moist-heat whitening resistance. The polar group-containing monomer (a1) can be used alone or in combination of two or more. Considering the viewpoint that the maturation tends to shorten, it is also desirable to use a hydroxyl-containing monomer and a carboxyl-containing monomer, a hydroxyl-containing monomer, and a tertiary amine-based monomer in combination.

The content of the polar group-containing monomer (a1) (the total content when two or more kinds are used in combination) must be 5 to 50% by weight, preferably 6 to 30% by weight, and more preferably 6 to 30% by weight relative to the entire copolymerization component. It is 7 to 25% by weight, and particularly preferably 8 to 20% by weight. If the content is too small, the moist-heat whitening resistance tends to decrease, and if it is too large, the storage stability tends to decrease when stored as an acrylic resin solution.

The content of the polar group-containing monomer (a1) when it contains a hydroxyl group-containing monomer is preferably 5 to 50% by weight, more preferably 6 to 35% by weight, and even more preferably 7 to 35% by weight relative to the entire copolymerization component. 25% by weight, particularly preferably 8-20% by weight. If the content of the hydroxyl-containing monomer is too small, the moist-heat whitening resistance tends to decrease, and if it is too large, the storage stability of the acrylic resin solution tends to decrease.

For applications where corrosion is a problem, the content when the polar group-containing monomer (a1) contains a carboxyl group-containing monomer is preferably 1% by weight or less based on the entire copolymerization component.

The (meth) acrylic acid alkyl ester monomer (a2), for example, the carbon number of the alkyl group is usually 1 to 20 (preferably 1 to 18, particularly preferably 1 to 12, and more preferably 1 to 8) Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and third butyl (meth) acrylate. , N-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, (formyl) Base) lauryl acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used individually by 1 type, and may use 2 or more types together.

Among these, from the viewpoints of excellent versatility and adhesive properties, methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferred.

The content of the (meth) acrylic acid alkyl ester monomer (a2) is preferably 20 to 95% by weight, more preferably 40 to 94% by weight, and still more preferably 45 to 93% by weight relative to the entire copolymerization component. %, Particularly preferably 50 to 92% by weight.

Examples of the other copolymerizable ethylenically unsaturated monomer (a3) include, for example, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxydiethylene glycol (methyl) Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, o-phenylphenoxyethyl (meth) acrylate, and other aromatic ring-containing monomers; cyclohexyl (meth) acrylate, Cyclohexyloxyalkyl (meth) acrylate, tert-butylcyclohexyloxyethyl (meth) acrylate, isoamyl (meth) acrylate, dicyclopentyl (meth) acrylate and other alicyclic rings Monomers; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2- (meth) acrylate Butoxyethyl, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, Ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octyloxyethylene glycol-polypropylene glycol Mono (meth) acrylate, lauryloxy polyethylene glycol mono (methyl ) Acrylate, stearyl glycol mono (meth) acrylate monomers containing an ether chains and the like. These can be used individually by 1 type or in combination of 2 or more types.

Among them, considering the viewpoint that adjustment of refractive index and adjustment of birefringence (Birefringence) are easy to perform, and viewpoint of excellent light leakage resistance, monomers containing aromatic rings are preferred (preferably benzyl (meth) acrylate, (Phenoxyethyl (meth) acrylate, phenoxy diethylene glycol (meth) acrylate), considering the adjustment of the refractive index and the adjustment of birefringence are easy to carry out, and for low-polar adherends (such as cycloolefins) From the viewpoint of excellent adhesion, etc., alicyclic monomers are preferred.

When using the acrylic adhesive composition of the present invention for polarizing plate applications, considering the light leakage resistance point of view, it is appropriate to adjust the content of aromatic ring-containing monomers and alicyclic monomers, and use the entire component after the endurance test. It is better to adjust the birefringence of the adhesive in such a manner that the birefringence is reduced. The content of the other copolymerizable ethylenically unsaturated monomer (a3) is preferably 35 wt% or less, and more preferably 25 wt% or less. If there are too many other copolymerizable ethylenically unsaturated monomers (a3), the light leakage resistance tends to decrease.

The acrylic resin (A) used in the present invention can be appropriately selected by appropriately selecting a polar group-containing monomer (a1), and it is more preferable to further appropriately select an alkyl (meth) acrylate-based monomer (a2) and other co-polymers. The polymerized ethylenically unsaturated monomer (a3) is produced by using these polymerization components, for example, mixing or dropping the polymerization component, a polymerization initiator, and polymerization in an organic solvent. The above-mentioned polymerization reaction can be performed in accordance with conventionally known polymerization methods such as solution radical polymerization, suspension polymerization, block polymerization, and emulsion polymerization, but among these, solution radical polymerization and block polymerization are preferred, and solution radical is particularly preferred. polymerization.

The organic solvents used in the above polymerization reaction include, for example, aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, and aliphatics such as n-propanol and isopropanol. Ketones such as alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Among these organic solvents, the ease of polymerization reaction, the effect of chain transfer, the ease of drying when the adhesive is applied, and the safety aspects are considered. Ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl alcohol Isobutanone is more preferred, and ethyl acetate, acetone, and methyl ethyl ketone are more preferred. These organic solvents may be used alone or in combination of two or more.

The polymerization initiator used in the radical polymerization is, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutane, which is a general radical polymerization initiator. Azo-based initiators such as nitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylpropionic acid), benzamidine peroxide, lauryl peroxide Organic peroxides such as osmium, di (third butyl) peroxide, cumene hydroperoxide, and the like can be appropriately selected for use in combination with the monomers. These polymerization initiators can be used alone or in combination of two or more.

The acrylic resin (A) used in the present invention must contain 5 to 50% by weight of the structural unit derived from the polar group-containing monomer (a1), preferably 6 to 35% by weight, and particularly preferably 7 to 25% by weight. %, And more preferably 8 to 20% by weight. If there are too few structural units derived from a polar group-containing monomer, the moisture and whitening resistance tends to decrease, and if too many, the storage stability of the acrylic resin solution tends to decrease.

The weight average molecular weight of the above-mentioned acrylic resin (A) is preferably 600,000 to 2.5 million, particularly preferably 800,000 to 2 million, even more preferably 1 to 1.8 million, and particularly preferably 1.1 to 1.6 million. If the weight-average molecular weight is too small, the durability tends to decrease. If the weight-average molecular weight is too large, a large amount of a diluent solvent is required during manufacture, and the drying property is reduced. The residual solvent in the adhesive layer is increased, and the heat resistance is reduced. tendency.

The dispersion degree (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 10 or less, particularly preferably 7 or less, and still more preferably 5 or less. If the degree of dispersion is too high, the reworkability or durability tends to decrease. The lower limit of the dispersion degree is usually one.

In addition, the weight average molecular weight is a weight average molecular weight obtained by using standard polystyrene molecular weight conversion, and is based on high-speed liquid chromatography (manufactured by Japan Waters, "Waters 2695 (bulk)" and "Waters 2414 (detector) ") 3 columns in series: Shodex GPC KF-806L (Excluding limit molecular weight: 2 × 10 ⁷ , separation range: 100 ~ 2 × 10 ⁷ , theoretical plate number: 10,000 layers / plate, filler material: styrene- Divinylbenzene copolymer, filler particle diameter: 10 μm), the number average molecular weight can also be measured by the same method. The degree of dispersion can be determined from the weight average molecular weight and the number average molecular weight.

The glass transition temperature (Tg) of the acrylic resin (A) is preferably -60 to 0 ° C, more preferably -50 to -20 ° C, and even more preferably -45 to -25 ° C. If the glass transition temperature is too high, the viscosity tends to decrease, and if it is too low, the heat resistance tends to decrease.

The glass transition temperature is calculated using the following Fox formula. Tg: glass transition temperature (K) of acrylic resin (A) Tga: glass transition temperature (K) of homopolymer of monomer A Wa: weight fraction of monomer A Tgb: of homopolymer of monomer B Glass transition temperature (K) Wb: weight fraction of monomer B Tgn: glass transition temperature of homopolymer of monomer N (K) Wn: weight fraction of monomer N (Wa + Wb + .... + Wn = 1) That is, the glass transition temperature (Tg) of the acrylic resin (A) is calculated by substituting the glass transition temperature and weight fraction of each monomer constituting the acrylic resin (A) into a homopolymer to the above-mentioned formula of Fox. value. In addition, the glass transition temperature when the monomer constituting the acrylic resin (A) is made into a homopolymer is usually measured by a differential scanning calorimeter (DSC), and a method according to JIS K7121-1987 and JIS K 6240 can be used. Perform the measurement.

The refractive index of the acrylic resin (A) is usually 1.440 to 1.600, preferably 1.460 to 1.550, and particularly preferably 1.470 to 1.500. If this refractive index reduces the refractive index difference of the laminated member, the light loss at the interface of the member is preferably reduced. The above-mentioned refractive index is measured by using a refractive index measuring device ("Abbe refractometer 1T" manufactured by Atago Co., Ltd.) on a NaD line at 23 ° C using an acrylic resin (A) made into a thin film.

The haze of the acrylic resin (A) single layer is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.5 or less. If the haze is too high, the image quality of a display using the haze tends to decrease. Haze is measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and calculates the difference between the obtained diffuse transmittance and total light transmittance into the following formula. The machine conforms to JIS K7361-1. Haze (%) = (diffuse transmittance / total light transmittance) × 100

In this way, the acrylic resin (A) used in the present invention was obtained.

<Silane coupling agent (B)> Generally, a silane coupling agent is an organic silicon compound containing one or more reactive functional groups and an alkoxy group in each structure. In the present invention, in the structure of the silane coupling agent (B) containing one or more reactive functional groups and alkoxy groups each, the oligomeric silane coupling agent having an alkoxy content of 15% by weight or less (B1).

The alkoxy group specified in the present invention refers to an alkoxy group derived from an alkoxysilane, and does not include an alkoxy group contained in the molecule other than the alkoxy group. For example: polyether modified silane, polyether chain end, polyether structure, excluding alkoxy group.

The above-mentioned reactive functional groups include, for example, epoxy groups, (meth) acrylfluorenyl groups, mercapto groups, hydroxyl groups, carboxyl groups, amine groups, amidoamine groups, isocyanate groups, and the like. Among these, the viewpoints of durability and reworkability are considered. Epoxy and mercapto are preferred.

Examples of the alkoxy group include methoxy, ethoxy, and propoxy. Among these, an alkyl group having 1 to 8 carbons is preferable, and an alkyl group having 1 to 2 carbons is particularly preferable, and specifically, a methoxy group and an ethoxy group.

Moreover, the silane coupling agent (B) may have an organic substituent other than a reactive functional group and an alkoxy group, for example, an alkyl group, a phenyl group, etc.

The alkoxy group content of the oligomeric silane coupling agent (B1) must be 15% by weight or less, preferably 1 to 15% by weight, particularly preferably 3 to 14.5% by weight, and even more preferably 5 to 14.5% by weight . If the alkoxy group content is too much, the long-term reworkability tends to decrease. If it is too small, the durability tends to decrease.

The weight average molecular weight of the oligomeric silane coupling agent (B1) is preferably 3,000 or more, particularly preferably 4,000 to 30,000, and even more preferably 4,500 to 20,000. When the weight average molecular weight is within the above range, there is a tendency that the balance between long-term reworkability and durability is excellent.

The weight average molecular weight is a weight average molecular weight obtained by converting a standard polystyrene molecular weight, and can be measured by the following method. Device: Gel permeation chromatography Detector: Differential refractive index detector RI (RI-8020 type manufactured by Tosoh Corporation, sensitivity 32) Column: TSKgel guardcolumn H _HR -H (1) (φ6mm × 4cm manufactured by Tosoh Corporation ), TSKgel GMH _HR- N (2) (φ7.8mm × 30cm, manufactured by Tosoh Corporation) Solvent: tetrahydrofuran (THF) Column temperature: 23 ° C Flow rate: 1.0mL / min

The reactive functional group equivalent of the oligomeric silane coupling agent (B1) is preferably 1,600 g / mol or less, more preferably 100 to 900 g / mol, and even more preferably 300 to 700 g / mol. When this reactive functional group equivalent is in the said range, there exists a tendency for durability to be more excellent.

The oligomeric silane coupling agent (B1) is an oligomeric silane coupling agent. In other words, it is a part of an organic silicon compound that is partially hydrolyzed and polycondensed to obtain oligomer type silicone such as dimer and trimer Compounds (organosilane compounds).

Oligomeric silane coupling agent (B1), for example: γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, etc. Partially hydrolyzed and polycondensed oligomeric organosilicon compounds (epoxy groups containing polysiloxyalkoxy oligomers, etc.), or ether-modified oligomeric oligomers Oligomeric silane coupling agents containing epoxy groups, such as physical organic silicon compounds; oligomeric organic silicon compounds obtained by partially hydrolyzing and polycondensing one of organic silicon compounds such as γ-mercaptopropyltriethoxysilane (Mercapto-containing polysiloxyalkoxy oligomers, etc.), etc., oligomeric mercapto-containing silane coupling agents; etc. Among these, an oligomeric silane coupling agent (B1) may be appropriately selected so as to meet their respective conditions. The oligomeric silane coupling agent (B1) may be used alone or in combination of two or more thereof.

Specific examples of the oligomeric silane coupling agent (B1) include a commercially available product "X-24-9590" (weight average molecular weight: 13,700, alkoxy group: methoxy group, alkane group) manufactured by Shin-Etsu Chemical Industry Co., Ltd. Oxygen content: 9.5% by weight, reactive functional group: epoxy group, epoxy equivalent: 592g / mol), "X-24-9589" (weight average molecular weight: 4,700, alkoxy group contained: ethoxy group, Alkoxy content: 13.2%, reactive functional group: epoxy group, epoxy equivalent: 1509g / mol), etc. Of these, X-24-9590 is particularly preferred.

The content of the oligomeric silane coupling agent (B1) is preferably 0.001 to 1 part by weight relative to 100 parts by weight of the acrylic resin (A), more preferably 0.015 to 0.5 part by weight, and still more preferably 0.020 to 0.3 parts by weight, and more preferably 0.025 to 0.15. If the content is too large, durability tends to decrease, and if it is too small, long-term reworkability tends to decrease.

In the acrylic adhesive composition of the present invention, a silane coupling agent other than the above-mentioned oligomeric silane coupling agent (B1) may be used as long as the effect of the invention is not hindered. However, the silane coupling agent If the content of the cross-linking agent is too large, the durability tends to decrease due to bleeding. Therefore, the content of the silane coupling agent other than the oligomeric silane coupling agent (B1), specifically, is preferably 0.5 part by weight or less based on 100 parts by weight of the acrylic resin (A), and more preferably It is 0.3 parts by weight or less, and particularly preferably 0.1 part by weight or less.

The acrylic adhesive composition of the present invention preferably contains a crosslinking agent (C) and an antistatic agent (D) in addition to the acrylic resin (A) and the silane coupling agent (B).

<Crosslinking agent (C)> Crosslinking agent (C), for example: isocyanate-based crosslinker, epoxy-based crosslinker, aziridine-based crosslinker, melamine-based crosslinker, aldehyde-based crosslinker Crosslinking agent, amine-based crosslinker, and metal chelator crosslinker, but among these, it is suitable to use the viewpoint of improving the adhesion to the substrate and the viewpoint of excellent reactivity with the acrylic resin (A). An isocyanate-based crosslinking agent is preferred.

The isocyanate-based cross-linking agent includes, for example, a m-phenylene diisocyanate-based cross-linking agent such as 2,4-m-phenylene diisocyanate and 2,6-m-phenylene diisocyanate, and 1,3-xylene dimethylbenzene. Aromatic compounds such as xylylene diisocyanate crosslinking agents such as isocyanate, diphenylmethane crosslinking agents such as diphenylmethane-4,4-diisocyanate, and naphthalene diisocyanate crosslinking agents such as 1,5-naphthalene diisocyanate Family isocyanate crosslinking agent; isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene Cyclohexyl-4,4'-diisocyanate, 1,3-diisocyanoxymethylcyclohexane, norbornane diisocyanate and other alicyclic isocyanate-based crosslinking agents; hexamethylene diisocyanate, tris Aliphatic isocyanate-based crosslinking agents such as methylhexamethylene diisocyanate; and adducts, biuret bodies, isocyanurate bodies, and the like of the above isocyanate-based compounds.

Among these isocyanate-based cross-linking agents, methylenediphenyl diisocyanate-based cross-linking agents are more ideal in terms of pot life and durability, and xylene diisocyanate-based cross-linking agents or those containing isocyanurate backbones are preferred. The isocyanate-based cross-linking agent is ideal in view of shortening the curing time, and the non-aromatic isocyanate-based cross-linker is preferable in view of yellowing resistance. Among them, specifically, methylenephenyl diisocyanate, xylene diisocyanate, an adduct of hexamethylene diisocyanate and trimethylolpropane, and an isocyanurate body, in consideration of durability From the viewpoint of excellent balance of pot life and cross-linking speed, it is ideal.

The epoxy-based crosslinking agents include, for example, bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, and glycerin. Triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, neopentyl Alcohol polyglycidyl tetraol, diglycerol polyglycidyl ether and the like.

The aziridine-based cross-linking agent is, for example, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N, N '-Diphenylmethane-4,4'-bis (1-aziridinecarboxyamidoamine), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxyamidoamine), etc. .

The melamine-based crosslinking agent is, for example, hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, hexapentoxymethyl melamine, hexahexyl Oxymethyl melamine, melamine resin, etc.

The aldehyde-based crosslinking agent includes, for example, glyoxal, malonaldehyde, succinaldehyde, malealdialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, benzaldehyde, and the like.

The amine-based crosslinking agent is, for example, hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine , Amine-based resin, polyamide.

The above-mentioned metal chelate-based cross-linking agents include, for example, ethyl, ethyl, and ethyl acetoacetate of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Coordination compounds, etc.

The said crosslinking agent (C) can be used individually or in combination of 2 or more types.

The content of the cross-linking agent (C) is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 1.5 parts by weight, and still more preferably 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the acrylic resin (A). If the content is too small, the durability tends to decrease, and if it is too large, the stress relaxation property will decrease, the substrate will tend to warp, or it will take a long time to mature.

<Antistatic agent (D)> The acrylic adhesive composition of the present invention should preferably contain an antistatic agent (D). The antistatic agent (D) is particularly preferably an ionic compound (D1). The ionic compound (D1) preferably contains an ionic compound composed of at least one of a metal salt and an organic salt from the viewpoint of antistatic properties.

Metal salts, for example: alkali metal salts such as lithium salt, sodium salt, calcium salt, potassium salt, or alkaline earth metal salts, sulfonium salts.

Organic salts include onium salts such as ammonium salts, imidazolium salts, pyridinium salts, piperidinium salts, pyrrolidinium salts, and sulfonium salts.

Among these, considering the viewpoint of excellent corrosion resistance, the viewpoint of excellent long-term reworkability, and the viewpoint of excellent storage stability, an organic salt is preferable, more preferably an ammonium cation, an imidazolium ion, a pyridinium ion, and a piperidinium ion. Onium salts composed of nitrogen-containing cations such as pyrrolidinium ions, especially alkyl ammonium salts, and even more preferably non-cyclic alkyl ammonium cations and N, N-bis (trifluoromethanesulfonyl) fluorene An ammonium salt composed of an amine anion, an ammonium salt composed of an ammonium cation and N, N-bis (fluorosulfonyl) fluorenimide anion.

The melting point of the ionic compound (D1) is preferably 10 to 100 ° C, more preferably 20 to 80 ° C, and even more preferably 25 to 50 ° C. If the melting point is too high, it tends to be precipitated at a low temperature, and if it is too low, the discoloration of the polarizing plate tends to occur in a hot and humid environment.

The content of the antistatic agent (D) is preferably 0.5 to 10 parts by weight relative to 100 parts by weight of the acrylic resin (A), more preferably 2 to 8 parts by weight, and still more preferably 2 to 5 parts by weight, especially It is preferably 2.5 to 4.5 parts by weight. If the content is too small, antistatic performance cannot be obtained, and display unevenness tends to occur due to static electricity. If the content is too large, the polarization of the polarizing plate is reduced, the resistance to moist heat and whitening is reduced, or the durability is liable to decrease.

In addition, the acrylic adhesive composition of the present invention may be blended with a resin component, an acrylic monomer, a polymerization inhibitor, an antioxidant, an anticorrosive agent, a cross-linking accelerator, and the like, as long as the effect of the present invention is not impaired. Various additives such as a radical generator, a peroxide, and a radical scavenger, and metal and resin particles are used as other components. In addition to the above, it may contain impurities and the like contained in a small amount of the raw materials of the constituents of the adhesive composition.

The content of the other components is preferably 5 parts by weight or less with respect to 100 parts by weight of the acrylic resin (A), particularly 1 part by weight or less, and 0.5 part by weight or less is preferable. If the content is too large, the compatibility with the acrylic resin (A) tends to decrease and the moisture-heat whitening resistance tends to decrease.

In this way, the acrylic resin of the present invention can be obtained by mixing the acrylic resin (A) and the silane coupling agent (B), the cross-linking agent (C), the antistatic agent (D), and other components as necessary. It is an adhesive composition. In addition, the mixing method is not particularly limited, and various methods such as a method of mixing the components at once, a method of mixing the arbitrary components, and a method of mixing the remaining components at once or sequentially can be adopted.

The acrylic adhesive composition of the present invention can be made into an adhesive by hardening (crosslinking), and further, an adhesive layer composed of the adhesive can be formed on an optical member (optical stack). Layer body) to obtain an optical member with an adhesive layer. In the above-mentioned optical member with an adhesive layer, it is preferable to provide a release sheet on the side opposite to the optical member surface of the adhesive layer.

The manufacturing method of the above-mentioned optical member with an adhesive layer can be enumerated as follows: [1] Applying an acrylic adhesive composition to the optical member, and drying and bonding the release sheet at room temperature (23 ° C) or adding A method of curing at least one of the conditions in a warm state to implement treatment, [2] coating an acrylic adhesive composition on a release sheet, bonding the optical member after drying, and at least one of room temperature or a warmed state The method of curing is carried out under conditions such as those described above. Among these, the method of [2] and the method of curing at room temperature are preferable from the viewpoint of not harming the optical member and the viewpoint of excellent adhesion to the optical member. Among the above, it is particularly effective when the optical member is a polarizing plate.

The curing process is performed in order to obtain the balance of the physical properties of the adhesive in terms of the reaction time of chemical crosslinking of the adhesive. The curing conditions are usually room temperature to 70 ° C and the time is usually 1 to 30 days. Specifically, for example, the conditions can be performed at 23 ° C for 1 to 20 days, 23 ° C for 3 to 10 days, and 40 ° C for 1 to 7 days.

When coating the above-mentioned acrylic adhesive composition, it is preferable to dilute the acrylic adhesive composition in a solvent before coating, and the dilution concentration is preferably 5 to 60% by weight in terms of the solid content concentration. It is particularly preferably 10 to 30% by weight. The solvent is not particularly limited as long as it can dissolve the acrylic adhesive composition. Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, methyl ethyl acetate, and ethyl ethyl acetate. Ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic solvents such as toluene and xylene; and alcohol solvents such as methanol, ethanol, and propanol. Among these, from the viewpoints of solubility, drying property, and price, ethyl acetate and methyl ethyl ketone are preferable.

The coating of the acrylic adhesive composition can be carried out in accordance with conventional methods such as roll coating, die coating, gravure coating, notch coating, and screen printing.

The gel fraction of the adhesive layer manufactured according to the above method, considering the durability and the viewpoint of suppressing the decline of the degree of polarization, is preferably 30 to 95% by weight, particularly preferably 40 to 90% by weight, and more preferably 60. ~ 85% by weight. If the gel fraction is too low, the reworkability tends to decrease, and if it is too high, the floating and peeling tend to occur.

The above-mentioned gel fraction is an index of the degree of crosslinking (degree of hardening), and can be calculated by the following method, for example. That is, from an optical member, particularly an adhesive sheet formed by forming an adhesive layer on a substrate such as a polarizing plate, the adhesive is picked by a picker, and the adhesive is coated on a 200 mesh SUS product. The metal mesh was immersed in ethyl acetate adjusted to 23 ° C for 24 hours to define the weight percentage of the remaining insoluble adhesive component in the metal mesh as the gel fraction.

When the gel fraction of the adhesive is adjusted to the above range, it can be achieved by adjusting the type and amount of the crosslinking agent.

The adhesive layer manufactured according to the above method has better adhesion when touched by a finger, and actually has better moisture permeability when practically adhered to an adherend, and tends to improve workability, which is ideal.

For the electrical properties of the adhesive layer obtained by using the acrylic adhesive composition of the present invention, the surface resistance 値 is preferably 1 × 10 ¹² Ω or less, particularly preferably 1 × 10 ¹¹ Ω or less, and more preferably 5 × 10 ¹⁰ Ω or less. If the surface resistance is too high, the polarizing plate and the adhesive layer are liable to be charged, and display unevenness tends to occur.

In addition, in the obtained optical member with an adhesive layer, the thickness of the dried adhesive layer should preferably be 5 to 200 μm, especially 10 to 100 μm is preferable, and 10 to 30 μm is more preferable. If the thickness is too small, the physical properties of the adhesive tend to be difficult to stabilize. If it is too thick, the amount of water infiltration from the ends will increase, and the long-term reworkability will tend to decrease.

In the present invention, an optical member with an adhesive layer, especially a polarizing plate with an adhesive layer, is obtained by peeling the release sheet directly or with a release sheet, and then bonding the adhesive layer to a glass substrate. It is supplied to, for example, an image display device.

The long-term adhesion (heavy workability) of the adhesive of the present invention can be appropriately determined according to the material of the adherend. For example, when bonding to a glass substrate such as a liquid crystal cell, the adhesion force after bonding for 1 day should be preferably 0.1 ~ 10N / 25mm, and more preferably 0.1 ~ 5N / 25mm. In addition, the adhesion strength after 20 days should be 0.1 ~ 20N / 25mm, more preferably 0.1 ~ 15N / 25mm, more preferably 0.1 ~ 10N / 25mm. After 50 days, the adhesive force should be 0.1 ~ 20N / 25mm, more preferably 0.1 ~ 15N / 25mm, especially 0.1 ~ 10N / 25mm.

The initial adhesion force can be calculated as follows. For a polarizing plate with an adhesive layer, cut it to a width of 25 mm, peel the release film, and push the adhesive layer side to an alkali-free glass plate (Corning Corporation, "EAGLE XG"), and polarize the light. The plate is bonded to the glass plate. Thereafter, an autoclave treatment was performed (50 ° C. × 0.5 MPa × 20 minutes), and then left at 23 ° C. × 50% RH for 24 hours, and then a peeling test was performed at a peeling angle of 180 ° and a peeling speed of 300 mm / min. For long-term reworkability, after the autoclave was processed, it was left to stand for a predetermined period of time at 23 ° C. × 50% RH, and then a peel test was performed at a peel angle of 180 ° and a peel speed of 300 mm / min.

The acrylic adhesive composition of the present invention can obtain an adhesive with excellent durability and moist heat whitening resistance, storage stability, good reworkability, and good balance, and is excellent as an adhesive for optical members, especially An adhesive for polarizing plates bonded to a polarizing plate and a glass substrate is useful.

Examples of the protective film constituting the polarizing plate include triethylfluorene-based cellulose films, acrylic films, polyethylene films, polypropylene films, cycloolefin films, and the like. Any polarizing plate can be used ideally, but a polarizing plate in which a cycloolefin film is laminated in particular is preferable from the viewpoint that the effect of the present invention can be easily obtained.

In addition, by using the above-mentioned adhesive, an image display device can be manufactured by combining a polarizing plate and a liquid crystal cell, and the obtained image display device can be manufactured with good accuracy and excellent durability. [Example]

The present invention will be described in more detail by the following examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist thereof. In the example, "part" and "%" represent weight basis.

First, various acrylic resins were prepared in the following manner. The weight average molecular weight, the degree of dispersion, and the glass transition temperature of the acrylic resin (A) and the silane coupling agent (B) were measured according to the methods described above. The viscosity was measured in accordance with JIS K5400 (1990), 4.5.3 Rotary Viscometer.

<Acrylic resin (A)> [Manufacture of acrylic resin (A-1)] A 4-neck round bottom flask equipped with a reflux cooler, a stirrer, a nitrogen blowing inlet, and a thermometer was charged with 2-hydroxyethyl acrylate ( a1) 6 parts, acrylic acid (a1) 0.7 parts, n-butyl acrylate (a2) 73.3 parts, benzyl acrylate (a3) 20 parts, ethyl acetate 53 parts, acetone 42 parts, azobis as a polymerization initiator 0.013 parts of isobutyronitrile (AIBN) raised the internal temperature to the boiling point and started the reaction. Then, 30 parts of ethyl acetate solution containing 0.04% AIBN was added dropwise, and after reacting at reflux temperature for 3.25 hours, it was diluted with ethyl acetate to obtain an acrylic resin (A-1) solution (solid content: 20.9%, viscosity: 4,770 mPa · s / 25 ° C, acrylic resin (A-1): glass transition temperature -43 ° C, weight average molecular weight 1.29 million, dispersion 4.3).

The single system used above uses products from the following manufacturers.・ 2-Hydroxyethyl acrylate (Tg-15 ° C manufactured by Osaka Organic Chemicals) ・ Acrylic acid (Tg106 ° C manufactured by Mitsubishi Chemical Corporation) ・ Butyl acrylate (Tg-56 ° C manufactured by Mitsubishi Chemical Corporation) ・ Benzyl acrylate (Osaka Organic Chemicals) Viscoat # 160 (Tg, 6 ° C, manufactured by the company). The above Tg is the Tg of the homopolymer of each monomer.

[Production of acrylic resins (A-2) to (A-4), (A'-1), and (A'-2)] Using the copolymerization components described in Table 1, the acrylic resin (A-1 ), And the acrylic resin (A-2) to (A-4), (A'-1), and (A'-2) solutions were obtained. The acrylic resins (A-2) to (A-4), (A'-1), and (A'-2) solutions obtained are described in Table 1 below.

【Table 1】 HEA: 2-hydroxyethyl acrylate, AAc: acrylic acid, BA: n-butyl acrylate, BzA: benzyl acrylate

<Silane coupling agent (B)> The following silane coupling agent (B) was prepared. The weight-average molecular weight of the silane coupling agent (B) was measured according to the aforementioned method. In addition, unless otherwise specified, the content of alkoxy groups, reactive functional groups, epoxy equivalents or mercapto group equivalents, and alkoxy groups contained therein are listed in Table 値.

・ (B1-1): ("X-24-9590" manufactured by Shin-Etsu Chemical Industry Co., Ltd., weight average molecular weight: 13,700, alkoxy content: 9.5%, reactive functional group: epoxy group, epoxy equivalent: 592 g / mol, containing alkoxy: methoxy)

・ (B1-2): ("X-24-9589" manufactured by Shin-Etsu Chemical Industry Co., Ltd., weight-average molecular weight: 4,700, alkoxy content: 14.5% (measurement 値), reactive functional groups: epoxy, epoxy Equivalent: 1,509g / mol, containing alkoxy: ethoxy: ethoxy and propenyloxy

The alkoxy group content of "X-24-9589" was measured by the following method, and the alkoxy group content was calculated. 1. Measurement Weigh about 50 mg of the sample into a small glass bottle, add 1 mL of d-chloroform to dissolve it, and prepare a 5% (w / v) chloroform solution. This was put into a test tube for NMR measurement, and ¹ HNMR measurement was performed under the following conditions. The obtained ¹ HNMR spectrum is shown in FIG. 1. ≪Measurement conditions≫ Measurement device: Ascend ^TM 400 made by Bruker Corporation Probe: cryo probe Pulse program: Single pulse measurement temperature: 23 ° C (296K) Accumulation times: 16 pulses Delay time: 10sec 2. of alkoxy content Calculate the signals A to F for the ¹ HNMR spectrum and assign them A (6.2, 6.0 ppm): propenyloxy, B (3.6 ppm): oxidized ethylene (ethylene oxide) chain, C (3.4 ppm): oxidized Ethyl chain terminal methoxy group, D (3.1,2.8,2.6ppm): epoxy group, E (1.2ppm): ethoxy group, F (0.1ppm): methyl group, and it is calculated according to the integral of these signals Alkoxy content. In addition, let the number of organic substituents (epoxy groups, methyl groups) be X, the number of alkoxy groups (ethoxy groups, propenyloxy groups) be R, and (X + R) / 2 main chains (-SiO-) .

・ (B'-1) ("X-41-1059A" manufactured by Shin-Etsu Chemical Industry Co., Ltd., weight average molecular weight: 2,270, alkoxy content: 42%, reactive functional group: epoxy group, epoxy equivalent: 350 g / mol, containing alkoxy: methoxy, ethoxy)

・ (B'-2) ("X-41-1805" manufactured by Shin-Etsu Chemical Industry Co., Ltd., weight average molecular weight: 3,450, alkoxy content: 50%, reactive functional group: mercapto group, mercapto equivalent: 800 g / mol, containing (Alkoxy: methoxy, ethoxy)

・ (B'-3) (made by Shin-Etsu Chemical Industry Co., Ltd., "X-41-1810", weight-average molecular weight: 640, alkoxy content: 30%, reactive functional group: mercapto group, mercapto equivalent: 450 g / mol, Contains alkoxy: methoxy)

・ (B'-4) 3-glycidoxypropyltrimethoxysilane ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd., molecular weight: 236.6, alkoxy content: 39% (calculated), reactivity Functional group: epoxy group, epoxy equivalent: 236.6 g / mol (calculated 値), alkoxy group contained: methoxy group), and regarding the alkoxy group content of B'-4, the weight of methoxy group is divided Pyrene obtained by molecular weight (3 methoxy groups, 1 methoxy group weight; 31, molecular weight 236.6). The epoxy equivalent is calculated based on a molecular weight of 1 mol relative to the epoxy group.

<Crosslinking agent (C)> The following are prepared as a crosslinking agent (C). (C-1): adduct of methylphenyl diisocyanate and trimethylolpropane ("CORONATE L55E" manufactured by Tosoh Corporation)

<Antistatic Agent (D)> The following are prepared as the antistatic agent (D). (D-1): Tri-n-butylmethylammonium N, N-bis (trifluoromethanesulfonyl) fluorenimide ("FC-4400" manufactured by 3M Corporation, melting point 27.5 ° C)

(D-2): An ionic compound composed of an aromatic ring-containing ammonium cation and bis (fluorosulfofluorenimidine) ("MP-446" manufactured by Daiichi Kogyo Pharmaceutical Co., melting point: 37 ° C)

(D-3): Lithium N, N-bis (trifluoromethanesulfonyl) fluorenimide ("Li-TFSI" manufactured by Morita Chemical Co., melting point 232 ~ 234 ° C)

<Examples 1 to 12, Comparative Examples 1 to 9> The above components (A) to (D) were blended as shown in Table 2 below, and the solid content concentration was adjusted to 12.5% with ethyl acetate to obtain acrylic adhesives.剂 组合 物。 Composition.

【Table 2】 Note: The values in parentheses are the parts by weight in terms of solid content.

Using the acrylic adhesive composition obtained as described above, a sample for evaluation was prepared as shown below, and the following properties were evaluated. The evaluation results are shown in Table 3 below.

[Production of polarizing plates [I] and [II] with an adhesive layer] The obtained acrylic adhesive composition was coated on a release sheet having a thickness of 38 μm ("Lumirror SP-0138BU" manufactured by Mitsui Chemicals TOHCELLO) The thickness after drying was 25 μm. After drying at 100 ° C. for 3 minutes, the adhesive layer on the opposite side to the release sheet was bonded to a polarizing plate on which both sides of a triethylfluorene cellulose (TAC) film were laminated. The surface of one of the TAC films was then cured at 23 ° C × 50% RH for 7 days to obtain a polarizing plate with an adhesive layer [I] (layer structure: release sheet / adhesive layer / TAC (Film 1 / Polarizer / TAC film 2, TAC film 1: thickness 40 μm, TAC film 2: 60 μm). In addition, the COP surface of the cycloolefin-based film / polarizing plate / TAC-based film that has been corona-treated was bonded to the adhesive layer, and the same procedure was performed to obtain a polarizing plate with an adhesive layer [II]. The TAC film is a triethylfluorene cellulose film (thickness: 60 μm), and the COP film is a cycloolefin film (thickness: 50 μm). Using the above-mentioned polarizing plate [I] with an adhesive layer and the polarizing plate [II] with an adhesive layer, the following evaluations were performed.

[Reworkability] The polarizing plate [I] with an adhesive layer was cut to a width of 25 mm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass ("EAGLE XG" by Corning Corporation: thickness (1.1mm), followed by lamination with 2kg rollers for 2 times, followed by autoclave treatment (0.5MPa × 50 ° C × 20 minutes), and allowed to stand for 1 day, 20 days, and 50 days in an environment of 23 ° C × 50% RH. The adhesive force at the time of peeling at a peeling angle of 180 ° and a peeling speed of 300 mm / min was measured and evaluated according to the following criteria. (Evaluation Criteria) ・ After 1 day A ・ ・ ・ 5N / 25mm or less B ・ ・ ・ Over 5N / 25mm and 10N / 25mm or less C ・ ・ ・ Over 10N / 25mm, or adhesive residue or substrate breakage ・ After 20 days A・ ・ ・ 5N / 25mm or less B ・ ・ ・ More than 5N / 25mm and 10N / 25mm or less C ・ ・ ・ More than 10N / 25mm and 15N / 25mm or less D ・ ・ ・ More than 15N / 25mm and 20N / 25mm or less E・ ・ ・ Over 20N / 25mm, or adhesive residue or substrate breakage ・ 50 days later A ・ ・ ・ 5N / 25mm or less B ・ ・ ・ Over 5N / 25mm and 10N / 25mm or less C ・ ・ ・ Over 10N / 25mm and 15N / 25mm or less D ・ ・ ・ More than 15N / 25mm and 20N / 25mm or less E ・ ・ More than 20N / 25mm, or adhesive residue or substrate fracture

[Durability] The obtained polarizing plates [I] and [II] with an adhesive layer were cut into 20 cm × 15 cm, the release sheet was peeled off, and the adhesive layer was pushed to an alkali-free glass (manufactured by Corning Corporation) "EAGLE XG": thickness 1.1 mm), after laminating it back and forth twice with a 2 kg roller, autoclave treatment (0.5 MPa x 50 ° C x 20 minutes) was performed to obtain a sample for the initial durability test. After exposing the obtained sample to (1) heat resistance (80 ° C × 500 hours), the following evaluation was performed on the polarizing plate. (Evaluation Criteria) ○ ... No foaming or end floating was observed on the entire surface of the polarizing plate. × ・ ・ ・ Foam or end floating was observed on the entire surface of the polarizing plate [Damp and heat whitening resistance] The obtained polarizing plate [II] with an adhesive layer was cut into 3.5 cm × 3.5 cm, The die was peeled off, and the adhesive layer was pressed to an alkali-free glass ("EAGLE XG" by Corning Corporation: thickness 1.1 mm), followed by laminating it back and forth twice with a 2 kg roller, and then performing an autoclave treatment (0.5 MPa x 50 ° C x 20 minutes) to prepare a sample for the test of moist heat and whitening resistance. The obtained sample was exposed to an environment of 60 ° C. × 90% RH for 250 hours, then taken out and left at room temperature. The haze after 3 hours was measured, and The following criteria are used to evaluate the resistance to moist heat and whitening. In addition, the haze value is the value after deducting the blank 1.1 mm alkali-free glass. (Evaluation criteria) ・ The haze at the time of removal is less than 1% ○ ・ ・ ・ 1% or more and less than 3% △ ... ・ 3% or more and less than 4% × ... ・ 4% or more Less than 1% ○ · · · · · 1% or more and less than 2% △ · · · 2% or more and less than 3% × · · · 3%

[Gel fraction] The obtained release sheet of the polarizing plate [I] with an adhesive layer was peeled off, and the adhesive was picked up by a picker from the adhesive layer, and the adhesive was coated with SUS The 200-mesh metal mesh was immersed in ethyl acetate adjusted to 23 ° C for 24 hours to define the weight percentage of the remaining insoluble adhesive component in the metal mesh as the gel fraction (%).

[Antistatic property] <Surface resistance 値> After leaving the polarizing plate [I] with an adhesive layer above in a gas environment of 23 ° C. × 50% RH for 24 hours, remove the release sheet of the adhesive layer. The surface resistivity of the adhesive layer was measured using a surface resistivity measuring device (manufactured by Mitsubishi Chemical Analytech Co., Ltd. under the device name "Hiresta-UP (MCP-HT450)").

【table 3】

From the above results, it can be seen that the acrylic resin (A) using more polar group-containing monomers than usual and the acrylic adhesive of the oligomeric silane coupling agent (B1) having an alkoxy group content of 15% by weight or less are used. Examples 1 to 12 of the adhesive obtained from the adhesive composition were excellent in long-term reworkability and resistance to moist heat and whitening.

On the other hand, an acrylic resin using an acrylic resin (A'-1, A'-2) containing not more polar monomers and a silane coupling agent having an alkoxy group content of more than 15% by weight is used. Comparative Examples 1 and 2 of the adhesives obtained from the adhesive composition were excellent in long-term reworkability, but poor in moisture and heat whitening. In addition, an adhesive obtained from an acrylic adhesive composition using an acrylic resin (A) having more polar group-containing monomers than usual and a silane coupling agent having an alkoxy group content of more than 15% by weight. Comparative Examples 3 to 9 are excellent in moist heat and whitening resistance, but have poor long-term heavy workability.

The silane coupling agent is hydrolyzed by the moisture in the adhesive system and is bonded to the glass surface through the silanol group to improve the adhesion. Acrylic resins containing a large amount of polar monomers to such an extent that they have good resistance to moist heat and whitening, are easily absorbed into the environment and are easily affected by hydrolysis. Therefore, there is a tendency that the long-term reworkability is lowered than usual. It can be seen that Comparative Examples 1 and 2 in which acrylic resins having a large amount of polar monomers are not used, and even if a silane coupling agent having an alkoxy content of more than 15% by weight is used, long-term reworkability remains a problem. On the other hand, it can be seen that in Examples 1 to 12, even if an acrylic resin with a large content of polar monomers having a good level of moisture and whitening resistance was used, an oligomer having an alkoxy content of 15% by weight or less was used. The physical silane coupling agent (B1) has excellent long-term reworkability and durability.

In addition, when the adhesive obtained by cross-linking the acrylic adhesive composition of Examples 1 to 12 is used, the polarizing plate and the liquid crystal cell are bonded to produce an image display device, and the obtained image display device can perform well. Made with precision and excellent durability.

The above-mentioned embodiments have been disclosed for specific forms of the present invention, but the above-mentioned embodiments are merely examples and are not intended to be limited explanations. Various modifications which are understood by those skilled in the art in this technical field are intended to be included in the scope of the present invention. [Industrial availability]

When the acrylic adhesive composition of the present invention is used as an adhesive for laminating a polarizing plate (protective film) and a liquid crystal cell (glass) when manufacturing a liquid crystal display device, it is possible to obtain a rework with excellent long-term display. And polarizers that use low-polarity films such as cycloolefin-based films as protective films still have excellent moisture and whitening resistance, and are used as adhesives for optical members for display and optical component bonding, especially It is useful as an adhesive for polarizing plates for bonding a polarizing plate to a glass substrate of a liquid crystal cell or the like.

Figure 1 shows the ¹ HNMR spectrum of the silane coupling agent "X-24-9589".

Claims (9)

An acrylic adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) having at least one reactive functional group and an alkoxy group in the structure, respectively, characterized in that: the acrylic The resin (A) contains 5 to 50% by weight of a structure derived from at least one polar group-containing monomer (a1) selected from a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer. A unit acrylic resin, the silane coupling agent (B) contains an oligomeric silane coupling agent (B1) having an alkoxy content of 15% by weight or less. For example, the acrylic adhesive composition according to the first patent application range, wherein the reactive functional group equivalent of the oligomeric silane coupling agent (B1) is 1,600 g / mol or less. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application range, wherein the weight average molecular weight of the oligomeric silane coupling agent (B1) is 3,000 or more. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope, wherein the polar group-containing monomer (a1) contains at least a hydroxyl monomer. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope further contains a crosslinking agent (C). For example, the acrylic adhesive composition of the first or second patent application range further contains an antistatic agent (D). An adhesive, which is characterized in that the acrylic adhesive composition according to any one of claims 1 to 6 of the patent application scope is crosslinked by using a crosslinking agent (C). An adhesive for polarizing plates is made by using an adhesive such as item 7 of the patent application scope. An image display device is formed by bonding a polarizing plate and a liquid crystal cell with an adhesive such as the seventh item in the patent application scope.