KR20190040190A - An acrylic pressure-sensitive adhesive composition, and a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive for a polarizing plate, - Google Patents

Abstract

When used as a pressure-sensitive adhesive for use in pasting a polarizing plate (protective film) and a liquid crystal cell (glass) at the time of manufacturing a liquid crystal display device, exhibits excellent reworkability over a long period of time, Sensitive adhesive composition which does not cause whitening whitening can be obtained. An acrylic pressure sensitive adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and at least one alkoxy group in the structure, wherein the acrylic resin (A) comprises a hydroxyl group - containing monomer, (B) is an acrylic resin containing 5 to 50% by weight of a structural moiety derived from at least one polar group-containing monomer (a1) selected from the group consisting of an alkyleneoxy group-containing monomer and an oligomer-type silane coupling agent having an alkoxy group content of 15% B1).

Description

An acrylic pressure-sensitive adhesive composition, and a pressure-sensitive adhesive using the same, a pressure-sensitive adhesive for a polarizing plate,

The present invention relates to an acrylic pressure-sensitive adhesive composition, and a pressure-sensitive adhesive comprising the same and a pressure-sensitive adhesive for a polarizing plate using the pressure-sensitive adhesive composition, and more particularly to a pressure-sensitive adhesive for a polarizing plate that exhibits excellent reworkability over a long period of time and is hardly affected by moisture, To an acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive.

Conventionally, a polarizing plate in which both surfaces of a polarizer made of a polyvinyl alcohol film or the like imparted with a polarizing function is coated with a protective film is laminated on the surface of a liquid crystal cell in which a liquid crystal component oriented between two glass plates is sandwiched, . In order to laminate a polarizing plate on the surface of the liquid crystal cell, a pressure-sensitive adhesive layer provided on the surface of the polarizing plate is usually brought into contact with the liquid crystal cell surface and pressed.

An adhesive containing a polyvinyl alcohol resin is suitably used as an adhesive for mixing and bonding these protective films with a polarizer. Specifically, an aqueous solution containing a polyvinyl alcohol resin and a crosslinking agent is coated on a polarizer, And then heated and dried to produce a polarizing plate. In the manufacturing process of the polarizing plate, moisture contained in the adhesive preferably penetrates the protective film. As the protective film, a triacetyl cellulose film (TAC film) having high moisture permeability has been used so far. However, recently, , An olefin-based film, in particular, a cycloolefin-based film (COP film) is used as a protective film of a polarizer in place of the TAC film from the viewpoint of durability.

The pressure-sensitive adhesive used for attaching these polarizing plates to the liquid crystal cell (glass substrate) is required to have durability such as heat resistance and humidity resistance. Particularly, in a high temperature and high humidity environment, moisture intrudes into the pressure-sensitive adhesive layer and the adhesiveness with the glass substrate is deteriorated, 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, improvement in wet heat resistance has been achieved by blending a silane coupling agent to the pressure-sensitive adhesive. However, when a silane coupling agent is blended, the silane coupling agent gradually reacts, There is a problem that the property is deteriorated.

When a cycloolefin-based film is used as a protective film of a polarizing plate, there is a problem (wet heat bleaching phenomenon) that the pressure-sensitive adhesive layer is whitened due to condensation when it is exposed to a humid environment.

In addition, although the pressure sensitive adhesive used in the conventional polarizing plate is divided depending on the type of the polarizing plate, a pressure sensitive adhesive which can be used even when the polarizing plate is different in terms of cost and workability has been required.

For example, Patent Document 1 discloses a pressure-sensitive adhesive composition comprising 100 parts by weight of a pressure-sensitive adhesive resin (A), an epoxy equivalent of 100 to 2000 g / mol and a content of an alkoxyl group of 5 to 100 g / (A1), a urethane pressure sensitive adhesive resin (A2) and a poly (meth) acrylate oligomer (B) obtained by polymerizing a monomer having no carboxyl group in the pressure - sensitive adhesive resin (A) Based pressure-sensitive adhesive resin (A3), and an ester-based pressure-sensitive adhesive resin (A3).

Patent Document 2 discloses a pressure-sensitive adhesive using an acrylic resin in which a polar group-containing monomer is largely incorporated in consideration of anti-wet heat resistance.

Patent Document 1 JP 2016-44291 A Patent Document 2 JP 2013-213203 A

However, since the functional group equivalent and the alkoxy group content are both broadly specified for the silane coupling agent (silicon alkoxy oligomer) used in the pressure sensitive adhesive described in Patent Document 1, various kinds of silane coupling agents can be used. However, There has been room for improvement in anti-wet heat whitening property when a protective film having a low moisture permeability such as an anti-moisture film is used.

On the other hand, Patent Document 2 which takes into account anti-wet heat whitening properties has a substrate that can be used for various optical members. However, since a large number of polar group-containing monomers are incorporated in the acrylic resin, hydrophilicity becomes strong, There is a problem in that when the high TAC or the acrylic film is used, the hydrolysis of the silane coupling agent is accelerated and the long-term recycled workability is lowered.

Therefore, in the present invention, under such a background, when used as a pressure-sensitive adhesive to be used for attaching a polarizing plate (protective film) to a liquid crystal cell (glass) at the time of manufacturing a liquid crystal display device, excellent reworkability is exhibited over a long period of time And an acrylic pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive free from whitening even when exposed to a high temperature and high humidity environment.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As a result of intensive studies in view of such circumstances, the inventors of the present invention have found that a pressure-sensitive adhesive composition containing an acrylic resin and a silane coupling agent has an acrylic resin containing a relatively large number of structural units derived from a polar group- It has been found that a pressure-sensitive adhesive which exhibits excellent reworkability over a long period of time and does not cause whitening under high temperature and high humidity conditions can be obtained by using a combination of a small oligomer type silane coupling agent.

That is, the present invention relates to an acrylic pressure sensitive adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and an alkoxy group in the structure, wherein the acrylic resin (A) contains a hydroxyl group - containing monomer, (B) is an acrylic resin containing 5 to 50% by weight of a structural unit derived from at least one polar group-containing monomer (a1) selected from a monomer containing a polar group and a nitrogen-containing monomer, and the silane coupling agent (B) Type silane coupling agent (B1).

The present invention also provides a pressure sensitive adhesive for a polarizing plate made by using a pressure sensitive adhesive comprising the acrylic pressure sensitive adhesive composition of the first aspect crosslinked by a crosslinking agent (C) as a second principle, a pressure sensitive adhesive for a polarizing plate using the pressure sensitive adhesive of the second aspect, An image display device comprising a polarizing plate and a liquid crystal cell laminated together as a pressure-sensitive adhesive according to the second aspect is a fourth aspect.

The present invention relates to an acrylic pressure sensitive adhesive composition containing an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and an alkoxy group in the structure, wherein the acrylic resin (A) contains a hydroxyl group - containing monomer, Wherein the silane coupling agent (B) is an oligomer type monomer having an alkoxy group content of not more than 15% by weight, wherein the silane coupling agent (B) is at least one type selected from the group consisting of And a silane coupling agent (B1). Therefore, the pressure-sensitive adhesive obtained by using the acrylic pressure-sensitive adhesive composition of the present invention can be used as a pressure-sensitive adhesive for use in pasting a polarizing plate (protective film) and a liquid crystal cell (glass) Exhibits excellent reworkability, is also excellent in anti-wet heat resistance and durability, and is very useful as a pressure-sensitive adhesive for a polarizing plate.

If the reactive functional group equivalent of the oligomer type silane coupling agent (B1) is 1,600 g / mol or less, the durability is further enhanced.

When the oligomer type silane coupling agent (B1) has a weight average molecular weight of 3,000 or more, the oligomer type silane coupling agent (B1) has further excellent workability and durability.

When the polar group-containing monomer (a1) contains at least a hydroxyl group monomer, it is more excellent in anti-wet heat resistance.

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

Hereinafter, the present invention will be described in detail.

Also, in the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate. The acrylic resin is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

The acrylic pressure sensitive 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 is preferably an acrylic resin containing 5 to 50% by weight of a structural unit derived from at least one polar group-containing monomer (a1) selected from a hydroxyl group-containing monomer, a carboxyl group- And is preferably an acrylic resin obtained by copolymerizing a copolymerizable component containing 5 to 50% by weight of 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 .

The copolymerizable component of the acrylic resin (A) may optionally contain a (meth) acrylic acid alkyl ester-based monomer (a2) and other copolymerizable ethylenically unsaturated monomer (a3).

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.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl Acrylate, hydroxypropyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate, caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) , And polyethylene glycol (meth) acrylate, and other oxyalkylene-modified monomers such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, hydroxyethyl acrylamide (Meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-chloro-2-hydroxypropyl (meth) acrylate. Containing monomer; and a hydroxyl group monomer such as 2,2-dimethyl-2-hydroxyethyl (meth) acrylate.

Among the above-mentioned hydroxyl group-containing monomers, a primary hydroxyl group-containing monomer is preferred from the viewpoint of excellent reactivity with a crosslinking agent and improvement of anti-wet heat resistance, and 2-hydroxyethyl (meth) 4-hydroxybutyl (meth) acrylate is preferably used from the viewpoints of quick reactivity with a crosslinking agent and shortening of aging. Further, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable from the viewpoint of easy production because of less impurities such as di (meth) acrylate.

As the hydroxyl group-containing monomer, it is also preferable to use a monomer having a content of di (meth) acrylate of 0.5 wt% or less as an impurity, particularly preferably 0.2 wt% or less, more preferably 0.1 wt% or less . Specifically, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate and 2-hydroxypropyl acrylate are particularly preferable.

Examples of the carboxyl group-containing monomer include dimer acids of acrylic acid such as (meth) acrylic acid and? -Carboxyethyl acrylate. Of these, from the viewpoint of anti-wet heat whitening property and stability in polymerization Methacrylic acid is preferable.

Examples of the nitrogen atom-containing monomer include amino group-containing monomers and amide group-containing monomers.

Examples of the amino group-containing monomers include monomers having a primary amino group such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate, monomers having a secondary amino group such as tert-butylaminoethyl , Tertiary amino group-containing monomers such as ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.

Among the above-mentioned amino group-containing monomers, tertiary amino group-containing monomers are preferable from the viewpoint of high crosslinking promoting effect and high storage stability of the resin.

In addition, heterocyclic amine monomers such as (meth) acryloylmorpholine are preferred from the viewpoint of excellent durability and excellent adhesion with metals and metal oxides. Among these, particularly preferred are dimethylaminoethyl (meth) acrylate and (meth) acryloylmorpholine.

Examples of the amide group-containing monomer include (meth) acrylamide, methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, isopropoxymethyl (Meth) acrylamide-based monomers such as acrylamide, n-butoxymethyl (meth) acrylamide and isobutoxymethyl (meth) acrylamide; (Meth) acrylamide monomers such as dialkyl (meth) acrylamide monomers, hydroxyl group-containing amide monomers such as N- (hydroxymethyl) acrylamide, and (meth) acryloylmorpholines.

Among the amide group-containing monomers, alkoxyalkyl (meth) acrylamide-based monomers and dialkyl (meth) acrylamide-based monomers are preferable from the viewpoints of the stability of the resin solution and from the viewpoint of inhibiting the migration of the antistatic agent.

Among such polar group-containing monomers (a1), it is preferable to use a hydroxyl group-containing monomer from the viewpoint of excellent anti-wet heat resistance.

The polar group-containing monomer (a1) may be used alone or in combination of two or more. It is also preferable to use a hydroxyl group-containing monomer, a carboxyl group-containing monomer, a hydroxyl group-containing monomer and a tertiary amine-based monomer in combination with a viewpoint that aging tends to be shortened.

The content of the polar group-containing monomer (a1) (when two or more thereof are used in combination, the total content thereof) is required to be 5 to 50% by weight, preferably 6 to 30% Particularly preferably 7 to 25% by weight, and more preferably 8 to 20% by weight.

When such a content is too small, the anti-wet heat resistance tends to deteriorate, while when it is too large, the storage stability of the acrylic resin solution tends to be lowered.

The content of the hydroxyl group-containing monomer as the polar group-containing monomer (a1) is preferably 5 to 50% by weight, more preferably 6 to 35% by weight, 25% by weight, particularly preferably 8 to 20% by weight.

When the content of the hydroxyl group-containing monomer is too small, the anti-wet heat resistance tends to decrease, while when it is too large, the storage stability of the acrylic resin solution tends to be lowered.

In the application where corrosion is a problem, the content of the polar group-containing monomer (a1) in the case of containing a carboxyl group-containing monomer is preferably 1% by weight or less with respect to the total copolymer component.

Examples of the alkyl (meth) acrylate ester monomer (a2) include alkyl groups having 1 to 20 carbon atoms, preferably 1 to 18 carbon atoms, particularly preferably 1 to 12 carbon atoms, and more preferably 1 to 8 carbon atoms. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert- butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl ) Acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate. These may be used alone or in combination of two or more.

Of these, methyl acrylate, ethyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate are preferable from the viewpoint of versatility and excellent adhesive property.

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

Examples of the other copolymerizable ethylenically unsaturated monomer (a3) include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, 2-hydroxy- (Meth) acrylate, cyclohexyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, tert-butylcyclohexyl (Meth) acrylate, isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate; alicyclic moieties such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl Acrylate, methoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, 2-butoxyethyl Methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol propylene glycol mono (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, Containing monomer such as acrylate, lauryloxypolyethylene glycol mono (meth) acrylate, stearoxypolyethylene glycol mono (meth) acrylate and the like. These may be used alone, or two or more of them may be used in combination.

Among them, aromatic ring-containing monomers are preferable from the viewpoints of easy adjustment of refractive index and birefringence and excellent light-fast wettability (particularly preferred are benzyl (meth) acrylate, phenoxyethyl (metha) ethyl acrylate, phenoxydiethylene glycol (Meth) acrylate), the refractive index and birefringence are easily adjusted, and the alicyclic monomer is preferable from the viewpoint of excellent adhesion to a low polarity adherend (e.g., cycloolefin).

When the acrylic pressure sensitive adhesive composition of the present invention is used as a polarizing plate application, it is preferable to adjust the content of the aromatic ring containing monomer and the alicyclic monomer from the viewpoint of light fast wettability and adjust the birefringence of the pressure sensitive adhesive so that the birefringence of the entire member after the durability test becomes small Do.

The content of the other copolymerizable ethylenically unsaturated monomer (a3) is preferably 35% by weight or less, more preferably 25% by weight or less. If the other copolymerizable ethylenically unsaturated monomer (a3) is too much, the light fast wettability tends to be lowered.

The acrylic resin (A) used in the present invention may be obtained by appropriately selecting the polar group-containing monomer (a1), preferably the (meth) acrylic acid alkyl ester monomer (a2) and the other copolymerizable ethylenically unsaturated monomer (a3) These polymerization components can be used, for example, by mixing or dropping such a polymerization component and a polymerization initiator in an organic solvent and then polymerizing them.

The polymerization reaction can be carried out by conventionally known polymerization methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like. Among them, solution radical polymerization and bulk polymerization are preferable, and solution radical polymerization to be.

Examples of the organic solvent used in the polymerization include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propyl alcohol, isopropyl alcohol and the like Aliphatic alcohols such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and the like.

Of these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene and methyl isobutyl ketone are preferably used because of the ease of polymerization reaction, chain transfer effect, ease of drying at the time of coating with a pressure-sensitive adhesive, And more preferably ethyl acetate, acetone, and methyl ethyl ketone.

These organic solvents may be used alone or in combination of two or more.

Examples of the polymerization initiator used in such solution radical polymerization include 2,2'-azobisisobutyronitrile, which is a conventional radical polymerization initiator, 2,2'-azobis-2-methylbutylol nitrile , Azo type initiators such as 4,4'-azobis (4-cyano valeric acid) and 2,2'-azobis (methyl propionic acid), benzoyl peroxides, lauroyl peroxides, di- Organic peroxides such as cumene hydroperoxide, and the like, and they can be appropriately selected and used in accordance with the monomers to be used. These polymerization initiators may be used alone or in combination of two or more.

The acrylic resin (A) used in the present invention needs to contain 5 to 50% by weight of the structural unit derived from the polar group-containing monomer (a1), preferably 6 to 35% by weight, 25% by weight, and more preferably 8 to 20% by weight. When the amount of the structural units derived from the polar group-containing monomer is too small, the anti-wet heat resistance tends to deteriorate, while when it is too large, the storage stability when the acrylic resin solution is used tends to be lowered.

The weight average molecular weight of the acrylic resin (A) is preferably from 600,000 to 250,000, particularly preferably from 800,000 to 200,000, more preferably from 1,000,000 to 1,800,000, and particularly preferably from 1,110,000 to 1,60,000 .

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 diluting solvent is required at the time of production, drying property is lowered and residual agent tends to increase in the pressure- .

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, more preferably 5 or less.

When the degree of dispersion is too high, the reworkability tends to deteriorate or the durability tends to deteriorate. The lower limit of the degree of dispersion is usually 1.

The above weight average molecular weight was a weight average molecular weight in terms of standard polystyrene molecular weight, and the weight average molecular weight was measured using a high performance liquid chromatograph ("Waters 2695 (main body)" and "Waters 2414 3 parts of -806L (exclusion limit molecular weight: 2 x 10 ⁷ , separation range: 100 to 2 x 10 ⁷ , theoretical number of steps: 10,000 units / filler material: styrene-divinylbenzene copolymer, Series, and the number average molecular weight can be measured by the same method. The degree of dispersion is determined by 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 占 폚, particularly preferably -50 to -20 占 폚, and more preferably -45 to -25 占 폚.

If the glass transition temperature is too high, the tackiness tends to decrease. If the glass transition temperature is too low, the heat resistance tends to decrease.

The glass transition temperature is calculated by the following Fox equation.

Tg: glass transition temperature (K) of the acrylic resin (A)

Tga: glass transition temperature (K) of homopolymer of monomer A

Wa: weight fraction of monomer A

Tgb: glass transition temperature (K) of the homopolymer of monomer B

Wb: weight fraction of monomer B

Tgn: Glass transition temperature (K) of homopolymer of monomer N

Wn: weight fraction of monomer N

(Wa + Wb + ... + Wn = 1)

That is, the glass transition temperature (Tg) of the acrylic resin (A) is a value obtained by applying the glass transition temperature and the weight fraction of the respective monomers constituting the acrylic resin (A) to be.

The glass transition temperature of the homopolymer of the monomer constituting the acrylic resin (A) is usually measured by a differential scanning calorimeter (DSC), and the glass transition temperature is measured by a method according to JIS K 7121-1987 or JIS K 6240 .

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. Such a refractive index is preferable because the difference in the refractive index between the members to be laminated is reduced to reduce the optical loss at the member interface.

The refractive index is a value measured at 23 占 폚 by NaD line using a refractive index measuring apparatus ("Abbe refractometer 1T" manufactured by Atago Co., Ltd.) of acrylic resin (A) formed into a thin film.

The haze of the single layer of the acrylic resin (A) is preferably 1.0 or less, particularly preferably 0.8 or less, more preferably 0.5 or less. If such a haze is too high, the image quality of the display using this as a pressure sensitive adhesive tends to be lowered.

The haze was calculated by measuring the diffuse transmittance and the total light transmittance using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) and substituting the values of the obtained diffuse transmittance and total light transmittance into the following formula. In addition, this machine conforms to JIS K 7361-1.

Haze (%) = (diffuse transmittance / total light transmittance) x 100

Thus, the acrylic resin (A) used in the present invention is obtained.

≪ Silane coupling agent (B) >

Usually, the silane coupling agent is an organosilicon compound containing at least one reactive functional group and at least one alkoxy group in the structure.

In the present invention, the silane coupling agent (B) containing at least one reactive functional group and alkoxy group in the structure contains an oligomer-type silane coupling agent (B1) having an alkoxy group content of not more than 15% by weight.

The alkoxy group defined in the present invention refers to an alkoxy group derived from an alkoxysilane, and an alkoxy group contained in other molecules is not included.

For example, the terminal or polyether structure of the polyether moiety of the polyether-modified silane is not included as an alkoxy group.

Examples of the reactive functional group include an epoxy group, a (meth) acryloyl group, a mercapto group, a hydroxyl group, a carboxyl group, an amino group, an amide group, and an isocyanate group. Of these, an epoxy group and a mercapto group are preferable from the viewpoint of excellent durability and reworkability.

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

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, and the like.

The content of the alkoxy group of the oligomer type silane coupling agent (B1) is required to be 15% by weight or less, preferably 1 to 15% by weight, particularly preferably 3 to 14.5% by weight, more preferably 5 to 14.5% by weight .

If the content of the alkoxy group is too large, the long-term lithographic printing plate precursor tends to be deteriorated. If too little, durability tends to deteriorate.

The weight average molecular weight of the oligomer type silane coupling agent (B1) is preferably 3,000 or more, particularly preferably 4,000 to 30,000, and more preferably 4,500 to 20,000.

When the weight average molecular weight is within the above range, the balance between long-term reworkability and durability tends to be excellent.

The weight average molecular weight is a weight average molecular weight in terms of standard polystyrene molecular weight, and can be measured by the following method.

Device: Gel permeation chromatograph

Detector: Differential refractive index detector RI (RI-8020 type manufactured by Toso Co., Ltd., sensitivity 32)

Column: TSKgel guardcolumn H _HR- H (1) (φ6 mm × 4 cm manufactured by Toso Corporation), TSKgel GM H _HR -N (2) (φ7.8 mm × 30 cm manufactured by Tosoh Corporation)

Solvent: tetrahydrofuran (THF)

Column temperature: 23 ° C

Flow rate: 1.0 mL / min

The reactive functional group equivalent of the oligomer type silane coupling agent (B1) is preferably 1,600 g / mol or less, particularly preferably 100 to 900 g / mol, and more preferably 300 to 700 g / mol.

When the reactive functional group equivalent is within the above range, there tends to be excellent durability.

The oligomer type silane coupling agent (B1) is an oligomer type silane coupling agent. In other words, the oligomer type silane coupling agent is an oligomer type organosilicon compound (organosiloxane compound) such as a dimer or trimer in which a part of the organosilicon compound is hydrolyzed and polycondensed, to be.

Examples of the oligomer-type silane coupling agent (B1) include oligomer-type silane coupling agents which are obtained by hydrolyzing a part of an organosilicon compound such as? -Glycidoxypropyltriethoxysilane,? -Glycidoxypropylmethyldiethoxysilane, An oligomer type epoxy group-containing silane coupling agent such as an organosilicon compound (epoxy group-containing silicon alkoxy oligomer or the like) or an oligomer type organosilicon compound in which some of these oligomer type organosilicon compounds are ether-modified; gamma-mercaptopropyltriethoxysilane Oligomer-type mercapto group-containing silane coupling agents such as oligomer-type organosilicon compounds (such as mercapto group-containing silicon alkoxy oligomers) in which a part of the organosilicon compounds of the present invention are hydrolyzed and polycondensed.

Of these, the oligomer-type silane coupling agent (B1) can be appropriately selected and used so as to satisfy the respective conditions. The oligomer type silane coupling agent (B1) may be used alone or in combination of two or more.

Specific examples of the oligomer type silane coupling agent (B1) include "X-24-9590" (weight average molecular weight: 13,700, content of alkoxy group: methoxy group, content of alkoxy group: 9.5 weight Epoxy group, epoxy equivalent: 592 g / mol), X-24-9589 (weight average molecular weight: 4,700, containing alkoxy group: ethoxy group, alkoxy group content: 13.2%, reactive functional group: epoxy group, epoxy equivalent : 1509 g / mol).

Among these, "X-24-9590" is particularly preferable.

The content of the oligomer type silane coupling agent (B1) is preferably 0.001 to 1 part by weight, particularly preferably 0.015 to 0.5 part by weight, more preferably 0.020 to 0.3 part by weight, per 100 parts by weight of the acrylic resin (A) , And more preferably 0.025 to 0.15. If the content is too large, the durability tends to deteriorate. If the content is too small, the long-term recycled content tends to deteriorate.

A silane coupling agent other than the oligomer type silane coupling agent (B1) may be used in the acrylic pressure sensitive adhesive composition of the present invention as long as the effect of the invention is not impaired. However, if the content of the silane coupling agent is too large, The durability tends to be lowered. Therefore, the content of the silane coupling agent other than the oligomer type silane coupling agent (B1) is preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, based on 100 parts by weight of the acrylic resin (A) , Particularly preferably 0.1 parts by weight or less.

The acrylic pressure sensitive 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) >

Examples of the crosslinking agent (C) include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a melamine crosslinking agent, an aldehyde crosslinking agent, an amine crosslinking agent and a metal chelating crosslinking agent. Among them, It is preferable to use an isocyanate-based crosslinking agent from the viewpoint of improving the reactivity with the acrylic resin (A) and from the viewpoint of excellent reactivity with the acrylic resin (A).

Examples of the isocyanate crosslinking agent include toluylene diisocyanate crosslinking agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylene diisocyanate crosslinking agents such as 1,3-xylene diisocyanate, Aromatic isocyanate crosslinking agents such as diphenylmethane crosslinking agents such as phenylmethane-4,4-diisocyanate and naphthalene diisocyanate crosslinking agents such as 1,5-naphthalene diisocyanate; aromatic isocyanate crosslinking agents such as isophorone diisocyanate, 1,4-cyclohexane Diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, Alicyclic isocyanate-based crosslinking agents such as N-diisocyanate, hexamethylene diisocyanate, tri Aliphatic isocyanate-based crosslinking agents such as methyl hexamethylene diisocyanate, and adducts, buretes, and isocyanurate compounds of the isocyanate-based compounds.

Among these isocyanate crosslinking agents, a tolylene diisocyanate crosslinking agent is preferable from the viewpoint of pot life and durability, and a xylene diisocyanate crosslinking agent or an isocyanurate skeleton-containing isocyanate crosslinking agent is preferable from the viewpoint of shortening the aging time And a non-aromatic-free isocyanate-based cross-linking agent is preferable from the viewpoint of yellowing resistance. Of these, tolylene diisocyanate, xylylene diisocyanate, adduct of hexamethylene diisocyanate and trimethylol propane, and isocyanurate compound are preferable from the viewpoint of excellent balance of durability, availability time and crosslinking rate .

Examples of the epoxy crosslinking agent include epoxy resins such as bisphenol A epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether , 1,6-hexanediol diglycidyl ether, trimethylol propane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl Ether, and the like.

Examples of the aziridine crosslinking agent include tetramethylolmethane-tri-? -Aziridinylpropionate, trimethylolpropane-tri-? -Aziridinylpropionate, N, N'-diphenylmethane- , 4'-bis (1-aziridine carboxamide), and N, N'-hexamethylene-1,6-bis (1-aziridine carboxamide).

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaputoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resin and the like. .

Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succinic aldehyde, maleindialdehyde, glutadialdehyde, formaldehyde, acetaldehyde, benzaldehyde and the like.

Examples of the amine-based crosslinking agent include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethyltetramine, isophoronediamine, amino resin and polyamide .

Examples of the metal chelate crosslinking agent include acetylacetone and acetacetyl ester coordination compounds of a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, .

The crosslinking agent (C) may be used alone or in combination of two or more.

The content of the crosslinking agent (C) is preferably 0.01 to 5 parts by weight, particularly preferably 0.05 to 1.5 parts by weight, more preferably 0.1 to 0.5 parts by weight, based on 100 parts by weight of the acrylic resin (A).

If the content is too small, the durability tends to be deteriorated. If the content is too large, the stress relaxation property tends to be lowered, and the substrate tends to be easily bent, or aging for a long time is required.

≪ Antistatic agent (D) >

The acrylic pressure sensitive adhesive composition of the present invention preferably further contains an antistatic agent (D), and the ionic compound (D1) is particularly suitable as the antistatic agent (D).

As such an ionic compound (D1), it is preferable to contain an ionic compound composed of at least one of a metal salt and an organic salt from the viewpoint of a countermeasure.

Examples of the metal salt include alkali metal salts or alkaline earth metal salts such as lithium salts, sodium salts, calcium salts and potassium salts, and phosphonium salts.

Examples of the organic salt include an onium salt such as an ammonium salt, an imidazolium salt, a pyridinium salt, a piperidinium salt, a pyrrolidinium salt and a sulfonium salt.

Among them, from the viewpoint of excellent corrosion prevention, excellent long-term reworkability, and excellent storage stability, organic salts are preferable, and ammonium salts such as ammonium cations, imidazolium cations, pyridinium cations and piperidinium cations , A pyrrolidinium cation and the like, particularly preferably an alkylammonium salt, more preferably a noncyclic tetraalkylammonium cation and an N, N-bis (trifluoromethanesulfonyl) imide anion , And ammonium salts composed of ammonium cations and N, N-bis (fluorosulfonyl) imide anions.

The melting point of the ionic compound (D1) is preferably from 10 캜 to 100 캜, particularly preferably from 20 캜 to 80 캜, and still more preferably from 25 to 50 캜. If the melting point is too high, it tends to precipitate at a low temperature. If the melting point is too low, discoloration of the polarizing plate tends to occur under a humid environment.

The content of the antistatic agent (D) is preferably from 0.5 to 10 parts by weight, more preferably from 2 to 8 parts by weight, still more preferably from 2 to 5 parts by weight, particularly preferably from 2 to 5 parts by weight based on 100 parts by weight of the acrylic resin (A) Is 2.5 to 4.5 parts by weight. If the content is too small, the antistatic property can not be obtained, and display unevenness due to static electricity tends to occur. When the content is too large, the polarizing degree of the polarizing plate is lowered or the anti-wet heat resistance is lowered or the durability tends to deteriorate have.

The acrylic pressure sensitive adhesive composition of the present invention may further contain other components such as a resin component, an acrylic monomer, a polymerization inhibitor, an antioxidant, a corrosion inhibitor, a crosslinking accelerator, a radical generator, a peroxide, Various kinds of additives such as additives, metals and resin particles, and the like. In addition to the above, a small amount of impurities or the like contained in the starting materials for the constituent components of the pressure-sensitive adhesive composition may also be contained.

The content of the other components is preferably 5 parts by weight or less, particularly preferably 1 part by weight or less, more preferably 0.5 part by weight or less, based on 100 parts by weight of the acrylic resin (A). When the content is too large, the compatibility with the acrylic resin (A) is lowered, and the anti-wet heat resistance is lowered.

Thus, the acrylic pressure sensitive adhesive composition of the present invention can be obtained by mixing the acrylic resin (A) and the silane coupling agent (B), if necessary, the crosslinking agent (C), the antistatic agent (D) and other components. The mixing method is not particularly limited, and various methods such as a method of collectively mixing the components, a method of mixing arbitrary components, and a method of collectively or sequentially mixing the remaining components are employed can do.

The acrylic pressure sensitive adhesive composition of the present invention can be made into a pressure sensitive adhesive by curing (crosslinking) the pressure sensitive adhesive composition, and the pressure sensitive adhesive layer made of such pressure sensitive adhesive is laminated on the optical member (optical laminated body) have.

It is preferable that the optical member with a pressure-sensitive adhesive layer is further provided with a release sheet on the surface opposite to the optical member surface of the pressure-sensitive adhesive layer.

As a method of producing the pressure-sensitive adhesive layer optical member,

(1) a method in which an acrylic pressure-sensitive adhesive composition is coated and dried on an optical member, and then a release sheet is laminated and subjected to treatment according to aging at at least one of a room temperature (23 ° C)

[2] A method in which an acrylic pressure-sensitive adhesive composition is coated and dried on a release sheet, and then an optical member is applied to the release sheet, and treatment is carried out by aging at at least one of a room temperature and a warmed state. Among them, the method of aging at room temperature in the method [2] is preferable from the viewpoint of not damaging the optical member and excellent adhesion with the optical member.

In the above, the case of the polarizing plate is particularly effective as the optical member.

Such aging treatment is carried out in order to balance the adhesive property as the reaction time of the chemical crosslinking of the pressure-sensitive adhesive. As the conditions for the aging, the temperature is usually from room temperature to 70 DEG C and the time is usually from 1 to 30 days. For example, at 23 占 폚 for 1 to 20 days, at 23 占 폚 for 3 to 10 days, at 40 占 폚 for 1 to 7 days, and the like.

In applying the pressure-sensitive adhesive composition, it is preferable to dilute the acrylic pressure-sensitive adhesive composition in a solvent and apply it. The dilution concentration is preferably 5 to 60% by weight, more preferably 10 to 30% by weight as a solid content concentration. The solvent is not particularly limited as long as it dissolves the acrylic pressure-sensitive adhesive composition, and examples thereof include ester solvents such as methyl acetate, ethyl acetate, methyl acetate and ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl Ketone solvents such as ketones, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol. Of these, ethyl acetate and methyl ethyl ketone are most suitably used in terms of solubility, drying, and cost.

The application of the acrylic pressure-sensitive adhesive composition is carried out by conventional methods such as roll coating, die coating, gravure coating, comma coating and screen printing.

The gel fraction of the pressure-sensitive adhesive layer produced by the above method is preferably from 30 to 95% by weight, particularly preferably from 40 to 90% by weight, more preferably from 60 to 90% by weight, To 85% by weight. If the gel fraction is too low, the reworkability tends to decrease. If the gel fraction is too high, there is a tendency that peeling or peeling is liable to occur.

The gel fraction is a standard for the degree of crosslinking (degree of curing), and is calculated, for example, by the following method. That is, the pressure-sensitive adhesive was picked from the pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer was formed on a base material such as an optical member, in particular, a polarizing plate, and the pressure-sensitive adhesive was wrapped with a 200 mesh SUS wire net, immersed in ethyl acetate adjusted to 23 DEG C for 24 hours , And the weight percentage of the insoluble portion of the adhesive component remaining in the wire net is taken as the gel fraction.

The gel fraction of the pressure-sensitive adhesive is adjusted to the above range by adjusting the type and amount of the cross-linking agent.

The pressure-sensitive adhesive layer produced by the above method is preferable because it has a good tactile feel as when it is contacted with a finger, because it has good wettability when adhered to an adherend.

As the electrical characteristics of the pressure-sensitive adhesive layer obtained by using the acrylic resin composition of the present invention, the surface resistance value is preferably 1 x 10 ¹² ? Or less, particularly preferably 1 x 10 ¹¹ ? Or less, more preferably 5 x 10 ¹⁰ Ω or less. When the surface resistance value is too high, the polarizing plate or the pressure-sensitive adhesive layer tends to be easily charged, and display unevenness tends to occur easily.

The thickness of the pressure-sensitive adhesive layer after drying in the optical member with a pressure-sensitive adhesive layer to be obtained is preferably 5 to 200 占 퐉, particularly preferably 10 to 100 占 퐉, and more preferably 10 to 30 占 퐉. If the thickness is too thin, the adhesive property tends to be unstable. If the thickness is too large, the amount of moisture settled from the end portion tends to increase, and the long-term reworkability tends to decrease.

In the present invention, an optical member with a pressure-sensitive adhesive layer, in particular, a polarizing plate with a pressure-sensitive adhesive layer, which is provided directly or after a release sheet is peeled off, is applied to an image display device after bonding the pressure-sensitive adhesive layer surface to a glass substrate.

The adhesive force (reworkability) of the pressure-sensitive adhesive of the present invention is appropriately determined depending on the material of the adherend or the like.

For example, in the case of bonding to a glass substrate such as a liquid crystal cell, the adhesive strength after 1 day of fusion is preferably 0.1 to 10 N / 25 mm, more preferably 0.1 to 5 N / 25 mm. The adhesive force after 20 days is preferably 0.1 to 20 N / 25 mm, more preferably 0.1 to 15 N / 25 mm, particularly preferably 0.1 to 10 N / 25 mm. The adhesive strength after 50 days is preferably 0.1 to 20 N / 25 mm, more preferably 0.1 to 15 N / 25 mm, particularly preferably 0.1 to 10 N / 25 mm.

The adhesive force is calculated as follows.

The polarizing plate with a pressure-sensitive adhesive layer was cut to a width of 25 mm, the releasing film was peeled off, the pressure-sensitive adhesive layer side was pressed against a non-alkali glass plate ("Eagle XG" manufactured by Corning Incorporated), and the polarizing plate and the glass plate were bonded. Thereafter, the substrate was subjected to an autoclave treatment (50 占 폚 占 0.5 MPa 占 20 minutes), then left at 23 占 폚 and 50% RH for 24 hours, then subjected to a peeling test at a feeling angle of 180 占 and a peeling speed of 300 mm / do. With respect to the long-term reworkability, after the autoclave treatment, the substrate is left at 23 ° C × 50% RH for a predetermined period, and then subjected to a peeling test at a peeling angle of 180 ° and a peeling rate of 300 mm / min.

The acrylic pressure-sensitive adhesive composition of the present invention is excellent in durability and anti-wet heat resistance, and is excellent in storage stability and reworkability. The pressure-sensitive adhesive for optical members, in particular, the polarizer plate and the glass substrate, And is useful as a pressure-sensitive adhesive.

Examples of the protective film constituting the polarizing plate include a triacetylcellulose film, an acrylic film, a polyethylene film, a polypropylene film and a cycloolefin film, and the present invention is suitable for a polarizing plate using any protective film But in particular, a polarizing plate in which a cycloolefin film is laminated is preferable from the viewpoint of easily obtaining the effect of the present invention.

Further, by using the above-mentioned pressure-sensitive adhesive, an image display apparatus can be manufactured by attaching the polarizing plate and the liquid crystal cell together, and the resulting image display apparatus can be manufactured with high precision and excellent in durability.

(Example)

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In the examples, " part " and "% "

First, various acrylic resins were prepared as follows. 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 above-mentioned method.

The measurement of the viscosity was carried out in accordance with 4.5.3 rotational viscometer method of JIS K 5400 (1990).

≪ Acrylic resin (A) >

[Production of acrylic resin (A-1)]

6 parts of 2-hydroxyethyl acrylate (a1), 0.7 part of acrylic acid (a1), and 0.1 part of n-butyl acrylate (a1) were placed in a four-necked round bottom flask equipped with a stirrer, a nitrogen gas inlet, 73.3 parts of benzyl acrylate (a3), 20 parts of benzyl acrylate (a3), 53 parts of ethyl acetate, 42 parts of acetone, and 0.013 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were added and the internal temperature was raised to the boiling point to initiate the reaction. Subsequently, 30 parts of an ethyl acetate solution containing 0.04% of AIBN was added dropwise, and the mixture was reacted at reflux temperature for 3.25 hours. After diluting with ethyl acetate, an acrylic resin (A-1) solution (solid content 20.9%, viscosity 4,770 mPa · s / , And an acrylic resin (A-1): glass transition temperature -43 캜, weight average molecular weight: 129,000, dispersion degree: 4.3).

The monomer used in the above was the one of the following manufacturers.

· 2-hydroxyethyl acrylate (Tg manufactured by Osaka Organic Chemical Industry Co., Ltd. -15 ° C)

Acrylic acid (Tg 106 ° C, manufactured by Mitsubishi Chemical Corporation)

Butyl acrylate (Tg -56 ° C, manufactured by Mitsubishi Chemical Corporation)

Benzyl acrylate (Bisquat # 160Tg 6 属 C, manufactured by Osaka Organic Chemical Industry Co., Ltd.)

The above Tg is the Tg of the homopolymer of each monomer.

[Production of acrylic resins (A-2) to (A-4) and (A'-1) and (A'-2)

(A-2) to (A-4), (A'-1), (A'-1) and (A'-1) were prepared in the same manner as in the above- 2) solution. The obtained acrylic resins (A-2) to (A-4), (A'-1) and (A'-2) solutions are as shown in Table 1.

≪ Silane coupling agent (B) >

As the silane coupling agent (B), the following were prepared. The weight average molecular weight of the silane coupling agent (B) was measured according to the above-mentioned method. The alkoxy group content, the reactive functional group, the epoxy equivalent or the mercapto equivalent, and the contained alkoxy group were adopted in catalog values unless otherwise specified.

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

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

The content of the alkoxy group in "X-24-9589" was measured by the following method, and the content of the alkoxy group was calculated.

1. Measurement

Approximately 50 mg of the sample was weighed with a vial (VIAL) and 1 mL of d-chloroform was added to dissolve it to prepare a 5% (w / v) chloroform solution. This was placed in a sample tube for NMR measurement, and ¹ HNMR measurement was carried out under the following conditions. The obtained ¹ H NMR spectrum is shown in Fig.

«Measurement conditions»

Measuring apparatus: Ascend ^TM 400 manufactured by Bruker

Probe: cryo probe

Pulse program: Single pulse

Measuring temperature: 23 ° C (296 K)

Number of accumulation: 16 times

Pulse delay time: 10 sec

2. Calculation of alkoxy group content

¹ with respect to the signal A~F HNMR spectrum, A (6.2, 6.0 ppm) : propenyloxy group, B (3.6 ppm): an ethylene oxide chain, C (3.4 ppm): ethylene oxide chain terminal methoxy group D ( 3.1, 2.8, 2.6 ppm): epoxy group, E (1.2 ppm): ethoxy group, F (0.1 ppm): methyl group and the alkoxy group content was determined by the integral value of these signals.

It is also assumed that the number of the organic substituent (epoxy group, methyl group) is X, the number of the alkoxy group (ethoxy group, propenyloxy group) is R, and the main chain (-SiO-) contains (X + R) / 2.

(B'-1)

(X-41-1059 A, manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight: 2,270 Alkoxy group content: 42%, reactive functional group: epoxy group, epoxy equivalent: 350 g / mol, contained alkoxy group: )

(B'-2)

(X-41-1805 manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight: 3,450, alkoxy group content: 50%, reactive functional group: mercapto group, mercapto equivalent: 800 g / mol, alkoxy group: methoxy group , Ethoxy group)

(B'-3)

(X-41-1810 manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight: 640, alkoxy group content: 30%, reactive functional group: mercapto group, mercapto equivalent: 450 g / mol, alkoxy group containing methoxy group )

(B'-4)

(Calculated value), reactive functional group: epoxy group, epoxy equivalent: 236.6 g / cm < 3 > mol (calculated value) containing alkoxy group: methoxy group)

As for the alkoxy group content of B'-4, a value obtained by subtracting the weight of the methoxy group by the molecular weight was adopted (the number of methoxy group 3, the weight of one methoxy group 31, the molecular weight 236.6). The epoxy equivalence was calculated as the molecular weight relative to 1 mol of the epoxy group.

≪ Crosslinking agent (C) >

The following crosslinking agent (C) was prepared.

(C-1): Adduct of tolylene diisocyanate and trimethylol propane ("Coronate L55E", manufactured by Toso Co., Ltd.)

≪ Antistatic agent (D) >

The following antistatic agent (D) was prepared.

N-bis (trifluoromethanesulfonyl) imide ("FC-4400" manufactured by 3M Company, melting point: 27.5 ° C)

(MP-446, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., melting point 37 ° C) composed of an aromatic ring-containing ammonium cation and bis (fluorosulfonylimide)

(Li-TFSI, manufactured by MORITAKA KAGAKU Co., Ltd., melting point 232 to 234 DEG C) (D-3): Lithium N, N-bis (trifluoromethanesulfonyl)

≪ Examples 1 to 12 and 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 an acrylic pressure sensitive adhesive composition.

Using the acrylic pressure-sensitive adhesive composition thus obtained, an evaluation sample was prepared as described below, and the following performance was evaluated. The evaluation results are shown in Table 3 below.

[Production of polarizer plates (I) and (II) with a pressure-sensitive adhesive layer]

The obtained acrylic pressure-sensitive adhesive composition was applied to a release sheet ("Rumira SP-0138BU" manufactured by Mitsui Kagaku Higashi Cellulose Co., Ltd.) having a thickness of 38 μm so as to have a thickness of 25 μm after drying and dried at 100 ° C. for 3 minutes, (TAC) film laminated on both surfaces of the polarizing plate was aged for 7 days under an environment of 23 deg. C x 50% RH on the surface of one TAC film of the polarizing plate on the opposite side of the release sheet to obtain a polarizing plate [I] (TAC film 2, TAC film 1: thickness 40 占 퐉, TAC film 2: 60 占 퐉).

Polarizer [II] with a pressure-sensitive adhesive layer was obtained in the same manner as in Example 1 except that the COP side of the cycloolefin-based film / polarizer / TAC-based film subjected to the corona treatment and the pressure-sensitive adhesive layer side were brought into contact with each other.

The TAC film is a triacetyl cellulose film (thickness: 60 占 퐉), and the COP film is a cycloolefin film (thickness: 50 占 퐉).

Sensitive adhesive layer-equipped polarizing plate [I] and the pressure-sensitive adhesive layer-containing polarizing plate [II].

[Workability]

The polarizing plate with pressure-sensitive adhesive layer [I] obtained above was cut to a width of 25 mm, the releasing sheet was peeled off, and the pressure-sensitive adhesive layer surface was pressed against alkali glass ("Eagle XG" (0.5 MPa 占 50 占 폚 for 20 minutes), and then left standing for 20 days and 50 days under the environment of 23 占 폚 and 50% RH. Thereafter, peeling angles of 180 占 and 300 mm / The adhesive strength at the time of peeling off at the peeling speed was measured and evaluated based on the following criteria.

(Evaluation standard)

· After 1 day

A ... 5 N / 25 mm or less

B ... 5N / 25mm or more 10N / 25mm or less

C · · · 10 N / 25 mm or more, or the remaining paste is broken or the substrate is broken

· After 20 days

A ... 5 N / 25 mm or less

B ... 5 N / 25 mm or more 10 N / 25 mm or less

C ... More than 10 N / 25 mm and less than 15 N / 25 mm

D ... More than 15 N / 25 mm and not more than 20 N / 25 mm

E · · · 20 N / 25 mm or more, or the remaining paste is broken or the substrate is broken

· After 50 days

A ... 5 N / 25 mm or less

B ... 5 N / 25 mm or more 10 N / 25 mm or less

C ... More than 10 N / 25 mm and less than 15 N / 25 mm

D ... More than 15 N / 25 mm and not more than 20 N / 25 mm

E · · · 20 N / 25 mm or more, or the remaining paste is broken or the substrate is broken

〔durability〕

The obtained polarizing plates [I] and [II] with the pressure-sensitive adhesive layer were cut into 20 cm × 15 cm, and the release sheet was peeled off to press the pressure-sensitive adhesive layer surface on a non-alkali glass ("Eagle XG" And then subjected to an autoclave treatment (0.5 MPa 占 50 占 폚 for 20 minutes) to prepare an initial durability test sample.

With respect to the obtained sample, the following evaluations were carried out on the polarizing plate after (1) exposing under the conditions of heat resistance (80 DEG C x 500 hours).

(Evaluation standard)

○ · · You can not see foaming or peeling at the end of the polarizer

× ·····················································································································································································

[Anti-wet heat whitening property]

The resulting pressure-sensitive adhesive layer polarizing plate [II] was cut into 3.5 cm x 3.5 cm, and the release sheet was peeled off to press the pressure-sensitive adhesive layer surface on an alkali-free glass (Eagle XG manufactured by Corning Incorporated: Then, autoclave treatment (0.5 MPa 占 50 占 폚 for 20 minutes) was carried out to prepare a sample for anti-wet heat whitening test.

The obtained sample was exposed for 250 hours under an environment of 60 캜 x 90% RH, and left at the extraction room temperature. Then, the haze after 3 hours from the time of taking out was measured, and the anti-wet heat resistance was evaluated. The haze is a value obtained by subtracting the value of 1.1 mm alkali-free glass as a blank.

(Evaluation standard)

· Hayes immediately after taking out

◎ · · · Less than 1%

○ 1% or more, less than 3%

△ ... 3% or more, less than 4%

X 4% or more

· Haze after 3 hours taken out

◎ · · · Less than 1%

○ 1% or more, less than 2%

△ ... 2% or more, less than 3%

X 3% or more

[Gel fraction]

The obtained release sheet of the polarizing plate with a pressure-sensitive adhesive layer [I] was peeled off, the pressure-sensitive adhesive was picked from the pressure-sensitive adhesive layer surface and wrapped with a 200 mesh wire net made of SUS, and immersed in ethyl acetate adjusted to 23 DEG C for 24 hours, The weight percentage of the pressure-sensitive adhesive component of the solution was defined as the gel fraction.

[Antistatic property]

<Surface resistance value>

After the polarizing plate [I] with the pressure-sensitive adhesive layer was allowed to stand in an atmosphere of 23 ° C × 50% RH for 24 hours, the release sheet of the pressure-sensitive adhesive layer was peeled off and measured by a surface resistivity meter (manufactured by Mitsubishi Chemical Corporation, UPMCP-HT450 &quot;) was used to measure the surface resistivity of the pressure-sensitive adhesive layer.

From the above results, in Examples 1 to 12 in which the pressure-sensitive adhesive obtained from the acrylic pressure-sensitive adhesive composition using the acrylic resin (A) containing more polar group-containing monomer than usual and the oligomer-type silane coupling agent (B1) having an alkoxy group content of 15% The long-term reworkability and wet heat resistance are excellent.

On the other hand, Comparative Examples 1 and 2 (Comparative Examples 1 and 2) using an acrylic pressure-sensitive adhesive composition obtained by using an acryl-based resin (A'-1, A'-2) containing no polar group-containing monomer and a silane coupling agent having an alkoxy group content of more than 15% The long-term reworkability is excellent, but the anti-wet heat resistance is poor.

In Comparative Examples 3 to 9 using an acrylic resin (A) containing a polar group-containing monomer in an amount larger than usual and a pressure-sensitive adhesive obtained from an acrylic pressure-sensitive adhesive composition using a silane coupling agent having an alkoxy group content of more than 15% by weight, And the long-term reworkability is low.

The silane coupling agent is hydrolyzed by moisture in the pressure-sensitive adhesive system and bonded to the glass surface through a silanol group to improve adhesion. In the case of an acrylic resin containing a polar monomer in a degree of good wet heat resistance and whitening property, moisture in the environment tends to be easily immersed in water and is susceptible to hydrolysis. Therefore, the long-term reworkability tends to be lowered than usual. In Comparative Examples 1 and 2 using an acrylic resin not containing a polar group monomer in a large amount, it can be understood that long-term recycling performance is not a problem even when a silane coupling agent having an alkoxy group content of more than 15% by weight is used. On the other hand, in Examples 1 to 12, since an oligomer type silane coupling agent (B1) having an alkoxy group content of not more than 15% by weight is used even in the case of using an acrylic resin containing a large amount of polar monomer to a degree of good anti- It can be seen that workability and durability are excellent.

The acrylic pressure-sensitive adhesive compositions of Examples 1 to 12 were obtained by attaching a polarizer plate and a liquid crystal cell using a crosslinked pressure-sensitive adhesive, and an image display apparatus was produced. The obtained image display apparatus was able to be manufactured with high precision and excellent durability.

Although the above embodiment has been described with reference to specific embodiments of the present invention, the above embodiments are merely illustrative and not restrictive. Various modifications that are obvious to those skilled in the art are expected to be within the scope of the present invention.

INDUSTRIAL APPLICABILITY The acrylic pressure-sensitive adhesive composition of the present invention exhibits excellent reworkability over a long period of time when used as a pressure-sensitive adhesive for use in pasting a polarizing plate (protective film) and a liquid crystal cell (glass) , A pressure sensitive adhesive excellent in anti-wet heat resistance can be obtained even when a polarizing plate having a low polarity film such as a cycloolefin-based film is used as a protective film, and a pressure-sensitive adhesive for optical members , Particularly, as a pressure-sensitive adhesive for a polarizing plate for bonding a polarizing plate and a glass substrate of a liquid crystal cell or the like.

Claims (9)

An acrylic pressure sensitive adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and at least one alkoxy group in the structure,
The acrylic resin (A) is an acrylic resin containing 5 to 50% by weight of a structural unit derived from at least one polar group-containing monomer (a1) selected from a hydroxyl group-containing monomer, a carboxyl group-containing monomer and a nitrogen-
Wherein the silane coupling agent (B) contains an oligomer-type silane coupling agent (B1) having an alkoxy group content of 15% by weight or less. The method according to claim 1,
Wherein the oligomer type silane coupling agent (B1) has a reactive functional group equivalent of 1,600 g / mol or less. The method according to claim 1 or 2,
The oligomer type silane coupling agent (B1) has a weight average molecular weight of 3,000 or more. 4. The method according to any one of claims 1 to 3,
Wherein the polar group-containing monomer (a1) contains at least a hydroxyl group monomer. 5. The method according to any one of claims 1 to 4,
Wherein the acrylic pressure-sensitive adhesive composition further comprises a crosslinking agent (C). 6. The method according to any one of claims 1 to 5,
And an antistatic agent (D). A pressure-sensitive adhesive comprising the acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 6 crosslinked by a crosslinking agent (C). A pressure-sensitive adhesive for a polarizing plate, comprising the pressure-sensitive adhesive according to claim 7. The image display apparatus according to claim 7, wherein the pressure-sensitive adhesive is formed by laminating a polarizing plate and a liquid crystal cell.

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