TW201829699A - Adhesive composition for polarizing plate, adhesive for polarizing plate, and polarizing plate provided with adhesive layer - Google Patents

Abstract

Provided is an adhesive composition for a polarizing plate, as an adhesive exhibiting excellent reworkability over a long time as well as having excellent durability and antistatic ability when used as an adhesive for bonding a polarizing plate and a liquid crystal cell, the adhesive composition containing an acrylic resin (A), a lithium salt (B), and a silane coupling agent (C) containing at least one of each of a reactive functional group and an alkoxy group bonded to a silicon atom in the structure thereof, the adhesive composition for a polarizing plate characterized in that the acrylic resin (A) has structural units derived from a carboxyl-group-containing monomer (a1), the content of the structural units derived from the carboxyl-group-containing monomer (a1) in the acrylic resin (A) being 4-10 wt%, and the weight-average molecular weight of the silane coupling agent (C) is 2,000 or greater.

Description

Adhesive composition for polarizing plate, adhesive for polarizing plate, and polarizing plate with adhesive layer

The invention relates to an adhesive composition for a polarizing plate, an adhesive for a polarizing plate, and a polarizing plate with an adhesive layer. The invention relates in detail to an adhesive composition for a polarizing plate, which can obtain excellent reworkability over time. (rework), and an adhesive layer having excellent durability and antistatic properties.

Liquid crystal display devices are widely used as image display devices for liquid crystal televisions, computer monitors, mobile phones, or digital cameras. This liquid crystal display device has a structure in which polarizing plates are laminated on both sides of a glass substrate (liquid crystal cell) in which a liquid crystal is sealed, and various optical elements such as a retardation plate are further laminated as required.

In the manufacture of a liquid crystal display device, an adhesive layer is usually provided on the release-treated film, and an adhesive layer on the side opposite to the release film is attached to a polarizing plate to manufacture a polarizing plate with an adhesive layer. When bonding to the liquid crystal cell, the release film is peeled off, and the adhesive layer and the glass substrate of the liquid crystal cell are attached to manufacture.

The adhesive used for bonding such a polarizing plate and a glass substrate of a liquid crystal cell requires durability such as heat resistance and humidity and heat resistance. Therefore, in the past, a carboxyl group-containing monomer containing a carboxyl-containing monomer as a copolymerization component having excellent durability has been used. The obtained acrylic resin adhesive (for example, refer to patent document 1). However, especially in a high-temperature and high-humidity environment, there is a problem that moisture penetrates into the adhesive layer, which reduces the adhesion with the glass substrate, and a part of the polarizing plate floats or peels off from the glass substrate. In order to solve such a problem, an silane coupling agent is added to the adhesive to improve the humidity and heat resistance.

In addition, as for the adhesive used for bonding the polarizing plate and the liquid crystal cell (glass substrate), it is also required to peel off the polarizing plate in the case where foreign matter enters or is staggered when the polarizing plate is bonded to the liquid crystal cell. Reusing the reworkability of the liquid crystal cell.

On the other hand, in a liquid crystal cell, static electricity may cause display failure due to disturbance of liquid crystal alignment. Therefore, static electricity countermeasures are adopted for polarizing plates. Specifically, it is known to impart antistatic properties to a protective film, or to adhere to a protective film. An antistatic agent is added to the agent layer to make a polarizing plate with an adhesive with excellent antistatic performance.

For example, as an adhesive having excellent durability and high antistatic performance under a high temperature and high humidity environment, an adhesive using an ionic compound as an antistatic agent is known. Generally speaking, if the ratio of the ionic compound in the adhesive composition is increased, the antistatic performance is improved, and the durability tends to be unsatisfactory. The antistatic performance and durability are in conflict with each other. tendency. Patent Document 2 describes that when an ionic compound having lithium ions is used, even if the ratio of the ionic compound is reduced, the antistatic performance can be improved, especially the humidification durability of the antistatic performance, which is preferable. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-105918 [Patent Document 2] Japanese Patent Laid-Open No. 2013-100386

[Problems to be Solved by the Invention] However, like the adhesives described in the aforementioned Patent Documents 1 and 2, an adhesive based on a combination of an acrylic resin using a large amount of a carboxyl group-containing monomer and an ionic compound having lithium ions is used. It has excellent durability, and its initial adhesion is also low, but the reworkability is deteriorated for a long period of time, and there are problems in reworkability.

In recent years, because the accuracy of manufacturing steps has increased, yield has improved, and there will not be as many defective products as in the past, and it will become a way to perform rework steps after defective products have accumulated to a certain number. Maintain reworkability for longer periods.

Therefore, in the context of the present invention, when an adhesive used for bonding a polarizing plate and a liquid crystal cell is provided, the present invention exhibits excellent reworkability over a long period of time, and exhibits excellent durability and antistatic properties. An adhesive composition for a polarizing plate, an adhesive for a polarizing plate, and a polarizing plate provided with an adhesive layer. [Means for solving problems]

The inventors of this case conducted a series of researches on this matter, and found that in the adhesive composition, by using an acrylic resin containing a relatively large amount of carboxyl-containing monomers as a lithium salt as an antistatic agent, In combination with a silane coupling agent having a specific molecular weight as a silane coupling agent, an adhesive composition for a polarizing plate that exhibits excellent reworkability over a long period of time, and has excellent durability and antistatic properties can be obtained.

That is, the first gist of the present invention is an adhesive composition for a polarizing plate, which contains an acrylic resin (A), a lithium salt (B), and a reactive functional group in the structure and an alkoxy group bonded to a silicon atom. The acrylic resin (A) has a structural unit derived from a carboxyl group-containing monomer (a1), and the acrylic resin (A) has a structural unit derived from a carboxyl group-containing monomer (a). The content of the structural unit of a1) is 4 to 10% by weight, and the weight average molecular weight of the silane coupling agent (C) is 2,000 or more.

The second gist of the present invention is an adhesive for polarizing plates obtained by cross-linking the adhesive composition for a polarizing plate of the first gist with a crosslinking agent (D), and the third gist of the present invention is A polarizing plate with an adhesive layer is obtained by laminating an adhesive layer containing the adhesive for a polarizing plate of the second gist on a polarizing plate. [Effect of the invention]

The adhesive composition for a polarizing plate of the present invention contains an acrylic resin (A), a lithium salt (B), and one or more silanes each containing a reactive functional group and an alkoxy group bonded to a silicon atom in the structure. Coupling agent (C), the acrylic resin (A) has a structural unit derived from a carboxyl-containing monomer (a1), and the content of the structural unit derived from a carboxyl-containing monomer (a1) in the acrylic resin (A) It is 4 to 10% by weight, and the weight average molecular weight of the silane coupling agent (C) is 2,000 or more. Therefore, the adhesive obtained by using the adhesive composition for polarizing plates exhibits excellent reworkability over a long period of time when used as an adhesive for bonding polarizing plates and liquid crystal cells, and has durability, Adhesives with excellent antistatic properties are very useful as adhesives for polarizing plates. Therefore, by using this adhesive composition for polarizing plates, a liquid crystal display device can be manufactured efficiently, and a liquid crystal display device excellent in durability can be obtained.

When the content of the lithium salt (B) is 0.3 to 8 parts by weight based on 100 parts by weight of the acrylic resin (A), the antistatic performance is more excellent.

When the content of the silane coupling agent (C) is 0.01 to 0.3 parts by weight based on 100 parts by weight of the acrylic resin (A), the reworkability and durability are more excellent.

If the reactive functional group of the silane coupling agent (C) is a mercapto group and the equivalent of the mercapto group is 100 to 2,000 g / mol, the reworkability and durability will be more excellent.

When the reactive functional group of the silane coupling agent (C) is an epoxy group and the weight average molecular weight is 4,000 or more, the reworkability and durability are more excellent.

In addition, if it contains a cross-linking agent (D), it can be an adhesive that exhibits excellent reworkability over a long period of time when used as an adhesive for bonding polarizing plates and liquid crystal cells, and has excellent durability and antistatic properties. .

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

The adhesive composition for polarizing plates of the present invention contains one or more silanes each containing an acrylic resin (A), a lithium salt (B), a reactive functional group in the structure, and an alkoxy group bonded to a silicon atom. The coupling agent (C) is an essential component.

<Acrylic resin (A)> In the acrylic resin (A) used in the present invention, the (meth) acrylic acid alkyl ester-based monomer (a2) is mainly used as a copolymerization component, and It is obtained by copolymerization with a carboxyl group-containing monomer (a1) containing a specific amount.

In the present invention, the acrylic resin (A) needs to contain 4 to 10% by weight of the structural unit derived from the carboxyl group-containing monomer (a1). The acrylic resin (A), for example, preferably contains the carboxyl group-containing monomer. (a1) 4 to 10% by weight of a copolymerized component obtained by copolymerization.

In addition, as for the copolymerization component of the acrylic resin (A), a functional group-containing monomer (a3) (but carboxyl group-containing monomer (a1) is not included) or other copolymerizable components may be included as required. Ethylenically unsaturated monomer (a4).

Examples of the carboxyl group-containing monomer (a1) include acrylic dimers such as (meth) acrylic acid and β-carboxyethyl acrylate, crotonic acid, maleic acid, maleic anhydride, fumaric acid, and citraconic acid. Acid, glutaric acid, itaconic acid, N-glycolic acid, cinnamic acid and the like. These can be used alone or in combination of two or more. Among these, (meth) acrylic acid is preferable from the viewpoint of availability as a pan-product, the viewpoint of cost, and the viewpoint of stability at the time of polymerization.

The content of the carboxyl group-containing monomer (a1) is preferably 4 to 10% by weight, more preferably 4.5 to 8% by weight, and still more preferably 5 to 7% by weight with respect to the entire copolymerization component. If the content is too small, the durability will be deteriorated, and if it is too large, the long-term reworkability will be deteriorated.

In the present invention, the (meth) acrylic acid alkyl ester-based monomer (a2) is preferably contained as a main component of the copolymerization component. As the (meth) acrylic acid alkyl ester-based monomer (a2), for example, an alkyl group may be mentioned. The carbon number is usually 1 to 20 (preferably 1 to 18, more preferably 1 to 12, and even more preferably 1 to 6.), specifically, methyl (meth) acrylate and (meth) Ethyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, third butyl (meth) acrylate, n-propyl (meth) acrylate, n-hexyl (meth) acrylate, ( 2-ethylhexyl methacrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, (meth) Stearyl acrylate, etc. These can be used alone or in combination of two or more.

Among these, alkyl (meth) acrylic acid alkyl ester monomers having 1 to 6 carbon atoms in the alkyl group are preferred. From the viewpoint of general versatility and adhesive properties, methyl acrylate, ethyl acrylate, N-butyl acrylate.

The content of the (meth) acrylic acid alkyl ester-based monomer (a2) is preferably 67 to 94% by weight, more preferably 75 to 90% by weight, and still more preferably 79 to 85% by weight with respect to the entire copolymerization component. Whether the content is too small or too large, there is a tendency that it is difficult to achieve a balance of adhesive properties.

Examples of the functional group-containing monomer (a3) include monomers having a functional group that reacts with a crosslinking agent (D) described later, and examples thereof include a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, Acetyl ethyl acetate monomers, isocyanate group-containing monomers, glycidyl group-containing monomers, etc. (but excluding the carboxyl group-containing monomer (a1) described above). Among these, in view of the fact that a crosslinking reaction can be performed efficiently, a hydroxyl-containing monomer is preferably used.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, ( Modified hydroxyalkyl acrylates such as 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl (meth) acrylate, and caprolactone such as caprolactone-modified 2-hydroxyethyl methacrylate Monomers, oxyalkylene modified monomers such as diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, etc. Mono-hydroxyl-containing monomers such as ethyl phthalic acid, N-hydroxymethyl (meth) acrylamide, hydroxyethyl acrylamide; 2-hydroxypropyl (meth) acrylate, (methyl ) 2-hydroxybutyl acrylate, 3-chloro 2-hydroxypropyl (meth) acrylate, and other monomers containing secondary hydroxyl groups; (2) 2-dimethyl 2-hydroxyethyl (meth) acrylate And other monomers containing tertiary hydroxyl groups. These can be used alone or in combination of two or more.

Among the above-mentioned hydroxyl-containing monomers, from the viewpoint of excellent reactivity with the cross-linking agent (D) and from the viewpoint of improving moist heat and whitening resistance, the monomers containing a primary hydroxyl group are preferred, and further, the di (methyl) ) From the viewpoint of having few impurities such as acrylate and easy production, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferably used.

Examples of the above-mentioned nitrogen atom-containing monomer include, for example, an amine group-containing monomer or a fluorenamine group-containing monomer, other nitrogen atom-containing monomers, and the like.

As for the amine group-containing monomer, for example, a primary amine group-containing monomer such as aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, or tert-butyl (meth) acrylate Monomers containing secondary amino groups such as ethylaminoethyl, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylamino (meth) acrylate Ethyl ester, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, N, N-dimethylaminopropylacrylamide, etc. Monomer, (meth) acrylic acid Heterocyclic amine monomers such as phthaloline. Among the above-mentioned amine group-containing monomers, a viewpoint that the effect of promoting cross-linking is good, a viewpoint of excellent aging characteristics, and a viewpoint of high storage stability of acrylic resins are considered. It is particularly preferably dimethylaminoethyl (meth) acrylate. In addition, in terms of excellent durability and excellent adhesion to metals or metal oxides, (meth) acrylic acid is preferred. Heterocyclic amine monomers such as phthaloline.

As for the fluorenamine group-containing monomer, for example, (meth) acrylamide; methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxylate Methyl (meth) acrylamide, isopropoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, isobutoxymethyl (meth) acryl Alkoxyalkyl (meth) acrylamide-based monomers, such as amidine; alkyl (meth) acrylamide, such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide Monomers; hydroxyl-containing amidine monomers such as N- (hydroxymethyl) acrylamide. Among the above-mentioned amide-group-containing monomers, from the viewpoint of the stability of the resin solution or the viewpoint of inhibiting the transfer of the antistatic agent, the alkoxyalkyl (meth) acrylamidoamine-based monomer and the alkyl ( Methacrylamide monomer.

Examples of the acetoacetic acid group-containing monomer include, for example, 2- (acetic acid ethylacetoxy) ethyl (meth) acrylate, allyl acetic acid acetate, and the like.

Examples of the isocyanate group-containing monomer include, for example, isopropyl-2-propenyloxyethyl isocyanate, 2-methacryloxyethyl isocyanate, or an alkylene oxide addition thereof. Things.

Examples of the above-mentioned glycidyl group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl (meth) acrylate.

The content of the functional group-containing monomer (a3) is preferably 0.001 to 3% by weight, more preferably 0.005 to 2.5% by weight, and still more preferably 0.01 to 2% by weight with respect to the entire copolymerization component. If the content is too small, the crosslinking reaction efficiency or reworkability tends to decrease, and if it is too large, the pot life tends to decrease.

Examples of the other copolymerizable ethylenically unsaturated monomer (a4) include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and 2-hydroxy (meth) acrylate -3-phenoxypropyl ester, o-phenylphenoxyethyl (meth) acrylate, and other aromatic ring-containing monomers; cyclohexyl (meth) acrylate, cyclohexyloxy (meth) acrylate Alicyclic monomers such as esters, tert-butylcyclohexyloxyethyl (meth) acrylate, isoamyl (meth) acrylate, and dicyclopentyl (meth) acrylate; (meth) acrylic acid- 2-methoxyethyl, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-butoxy diethylene glycol (meth) acrylate, methoxy diethylene glycol (meth) acrylate, methoxy triethylene glycol (meth) acrylate, ethoxy diethylene glycol Alcohol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octyloxyethylene glycol polypropylene glycol mono (meth) acrylate Lauric acid oxypolyethylene glycol mono (meth) acrylate, stearyloxy Ethylene glycol mono (meth) acrylate monomers containing an ether chains and the like. These can be used alone or in combination of two or more.

In addition, from the viewpoint of easily adjusting the refractive index and birefringence, it is preferable to use an aromatic ring-containing monomer as another copolymerizable ethylenically unsaturated monomer (a4), and particularly preferably benzyl (meth) acrylate. In addition, considering that it is easy to adjust the refractive index and birefringence, and from the viewpoint of excellent adhesion of the adherend, it is preferable to use benzyl (meth) acrylate and alkyl (meth) acrylate having 1 to 6 carbon atoms. The monomer (a2) is used in combination.

The content of the other copolymerizable ethylenically unsaturated monomer (a4) is preferably 0 to 25% by weight, more preferably 5 to 22% by weight, and still more preferably 12 to 20% by weight, relative to the entire copolymerization component. Too much or too little of this content tends to reduce light leakage resistance.

The acrylic resin (A) used in the present invention can be further selected by appropriately selecting a specific amount of the carboxyl group-containing monomer (a1), the main (meth) acrylic acid alkyl ester monomer (a2), The required functional group-containing monomer (a3) and other copolymerizable ethylenically unsaturated monomers (a4) are produced by polymerizing copolymerization components.

As the polymerization method of the acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, block polymerization, and emulsion polymerization can be used. For example, a copolymerization component is mixed or dropped in an organic solvent, A polymerization initiator is used to perform polymerization under specified polymerization conditions. Among them, solution radical polymerization and block polymerization are preferred, and solution radical polymerization is particularly preferred.

Examples of the organic solvent used in the above polymerization include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propanol, and isopropyl Aliphatic alcohols such as alcohols, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Among these solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, methyl, etc. are considered in terms of the ease of polymerization reaction, the effect of chain transfer, or the ease and safety of drying when the adhesive is applied. Isobutyl ketone is particularly preferably ethyl acetate, acetone, methyl ethyl ketone.

In addition, the polymerization initiator used in the solution radical polymerization may be, for example, 2,2'-azobisisobutyronitrile, 2,2'-azo which is a common radical polymerization initiator. Azo initiators such as bis-2-methylbutyronitrile, 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylpropionic acid), peroxide Organic peroxides such as benzamidine, lauryl peroxide, di-tert-butyl peroxide, cumene hydrogen peroxide, and the like can be appropriately selected and used in combination with the monomers 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 be an acrylic resin containing 4 to 10% by weight of a structural unit derived from a carboxyl-containing monomer (a1), preferably 4.5 to 8% by weight, and particularly preferably 5 to 7% by weight. . If the structural unit derived from the carboxyl group-containing monomer (a1) is too small, the durability will be deteriorated, and if it is too large, the reworkability will be deteriorated, and the object of the present invention cannot be achieved.

In addition, the acrylic resin (A) used in the present invention preferably contains a structural unit derived from a hydroxyl-containing monomer, and the content thereof is preferably 0.001 to 3% by weight, more preferably 0.005 to 2.5% by weight, and still more preferably 0.01 to 2 weight%. When there are too few structural units derived from a hydroxyl-containing monomer, the maturation characteristics tend to decrease, or the heat resistance and durability tend to decrease.

The weight average molecular weight of the above-mentioned acrylic resin (A) is preferably 800,000 to 2 million, particularly preferably 1 to 1.8 million, and further preferably 1.3 to 1.5 million. If the weight average molecular weight is too small, the durability tends to decrease. If it is too large, the viscosity tends to be high, and a large amount of a diluent solvent is required during production. Drying properties are reduced, residual solvents in the adhesive layer are increased, and heat resistance is reduced. .

The dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 15 or less, more preferably 10 or less, further preferably 5 or less, and particularly preferably 4.5 or less. If the degree of dispersion is too high, cohesive force tends to decrease. The lower limit of the degree of dispersion is usually two.

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

The glass transition temperature (Tg) of the acrylic resin (A) is preferably -80 to 0 ° C, more preferably -60 to -15 ° C, and even more preferably -50 to -20 ° 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 was calculated from the following Fox equation. 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 (K) of homopolymer of monomer N Wn: weight fraction of monomer N (Wa + Wb + ･ ･ ･ + Wn = 1) That is, the values obtained by substituting the glass transition temperature and the weight fraction when the monomers constituting the acrylic resin are homopolymerized into the above-mentioned Fox formula. In addition, the glass transition temperature when the monomer constituting the acrylic resin (A) is homopolymerized is usually measured by a differential scanning calorimeter (DSC), and can be obtained by following JIS K7121-1987 or JIS K 6240 method.

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

<Lithium salt (B)> In the present invention, it is necessary to contain a lithium salt (B) as an antistatic agent. As the lithium salt, a commonly known lithium salt known as an antistatic agent can be used. Lithium ions constituting a lithium salt have a small atomic radius among various metal ions, and are easy to move in the formed adhesive layer, exhibiting excellent antistatic properties.

As for the lithium salt (B), a halogen-containing lithium salt is preferably used, and examples thereof include LiCl, LiBr, LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li ( C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, and the like. In addition, the above-mentioned alkylene glycol dialkyl ether complex of the halogen-containing lithium salt can also be used. As for the alkylene glycol dialkyl ether, tetraethylene glycol diethyl ether and tetraethylene glycol dimethyl ether are preferable.

Among them, considering the availability of ionic compounds with good ion dissociation, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C and other fluorine-containing lithium salts, especially Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N and other fluorine-containing sulfonium imine lithium salts.

In the present invention, from the viewpoint of compatibility, fluorine-containing fluorene such as Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, and Li (C ₄ F ₉ SO ₂ ) ₂ N is preferably used. As the alkylene glycol dialkyl ether complex of a lithium imide salt, lithium bistrifluoromethanesulfonylimide lithium tetraethylene glycol dimethyl ether is particularly suitable.

The content of the lithium salt (B) is preferably 0.3 to 8 parts by weight, more preferably 0.5 to 6 parts by weight, and still more preferably 0.8 to 4 parts by weight based on 100 parts by weight of the acrylic resin (A). If the content is too small, the antistatic performance tends to decrease, and if it is too large, the lithium salt will ooze out and the durability will tend to decrease.

As the antistatic agent, an ionic compound other than the lithium salt (B) used in the present invention (for example, a lithium salt other than the lithium salt such as sodium salt and potassium salt) can be used within a range that does not impair the effect of the present invention. Alkali metal salts, organic salts such as ammonium salts, and imidazole salts, etc.), if the ionic compound is too much, the bleeding tends to decrease and the durability tends to decrease. Therefore, specifically, it is preferable to 100 parts by weight of the acrylic resin (A) It is 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less.

<Silane coupling agent (C)> The silane coupling agent structure contains an organic silicon compound having one or more reactive functional groups and one alkoxy group bonded to a silicon atom. In the present invention, as the silane coupling agent, it is necessary to use a silane coupling agent (C) having a weight average molecular weight of 2,000 or more.

Examples of the reactive functional group include an epoxy group, a (meth) acrylfluorenyl group, a mercapto group, a hydroxyl group, a carboxyl group, an amine group, a fluorenamine group, and an isocyanate group.

In terms of the alkoxy group bonded to the silicon atom described above, in view of durability and storage stability, an alkoxy group having 1 to 8 carbon atoms is preferable, and a methoxy group, an ethoxy group, and a reactive functional group are particularly preferable. When it is an epoxy group, it is preferable to include an ethoxy group from the viewpoint of reworkability, and when a reactive functional group is a mercapto group, it is preferable to include a methoxy group from the viewpoint of durability.

In addition, the silane coupling agent (C) may have a reactive functional group and an organic substituent other than an alkoxy group bonded to a silicon atom, such as an alkyl group, a phenyl group, and the like.

The weight average molecular weight of the silane coupling agent (C) needs to be 2,000 or more, preferably 2,000 to 16,000, more preferably 2,000 to 15,000, and further preferably 2,000 to 14,000. If the weight average molecular weight is too small, long-term reworkability tends to deteriorate, and if it is too large, compatibility tends to decrease, bleeding tends to occur easily, and durability tends to decrease.

In addition, the weight average molecular weight when the reactive functional group of the silane coupling agent (C) is an epoxy group is usually 4,000 or more, preferably 4,000 to 16,000, and particularly preferably 4,000 to 14,000. If the weight average molecular weight is too small, the long-term reworkability tends to decrease, and if the weight average molecular weight is too large, the compatibility decreases, the bleeding tends to occur, and the durability tends to decrease.

In addition, the said weight average molecular weight is a weight average molecular weight converted from the molecular weight of a standard polystyrene, and was measured by the following method. Device: Gel permeation chromatography Detector: Differential refractive index detector RI (RI-8020, manufactured by Tosoh Corporation, sensitivity 32) Column: TSKguardcolumn H _HR -H (1 branch), manufactured by Tosoh Corporation (φ6mm × 4cm) 、 (TSK gel GMH _HR -N (2 pcs) (φ7.8mm × 30cm) Solvent: Tetrahydrofuran (THF) Column temperature: 23 ℃ Flow rate: 1.0mL / min

The amount of the alkoxy group bonded to the silicon atom of the silane coupling agent (C) is preferably 1 to 70% by weight, more preferably 3 to 30% by weight, and still more preferably 5 to 20% by weight. If the amount of the alkoxy group bonded to the silicon atom is too small, the adhesiveness with the adherend tends to decrease, and the durability tends to decrease, and if too much, the long-term reworkability tends to decrease.

In addition, the reactive functional group equivalent of the silane coupling agent (C) is preferably 100 to 2,000 g / mol, more preferably 200 to 1,900 g / mol, and further preferably 300 to 1,800 g / mol in view of adhesion. . If the reactive functional group equivalent is too small, the reworkability tends to decrease, and if it is too large, the durability under moist heat resistance tends to decrease.

In addition, the thiol equivalent when the reactive functional group of the silane coupling agent (C) is a thiol group is 100 to 2,000 g / mol, more preferably 200 to 1,000 g / mol, and more preferably 300 in consideration of adhesion. ~ 650g / mol. If the reactive functional group equivalent is too small, the reworkability tends to decrease, and if it is too large, the durability under moist heat resistance tends to decrease.

Silane coupling agent (C) is an oligomer type organosilicon compound (organosiloxane compound) such as dimer or trimer obtained by partial hydrolysis and polycondensation of an organosilicon compound. For example, 3-mercaptopropane Thiol-containing oligomeric silanes obtained by hydrolyzing and condensing a part of thiol-containing silane compounds such as trimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane Coupling agent, or alkyl-containing silane compounds such as the above mercapto-containing silane compounds and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Thiol-containing oligomeric silane coupling agents such as co-condensates. Among these, it may be appropriately selected so as to conform to the weight-average molecular weight, and it may be used singly or in combination of two or more kinds.

As the silane coupling agent (C) used in the present invention, specifically, "X-24-9579A" (weight average molecular weight: 2,370, reactive functional group: mercapto group), which is a commercially available product manufactured by Shin-Etsu Chemical Industry Co., Ltd. can be used. , Alkoxy group bonded to silicon atom: methoxy group, epoxy equivalent weight: 311 g / mol), "X-24-9589" (weight average molecular weight: 4,700, reactive functional group: epoxy group, and silicon atom Bonded alkoxy group: ethoxy group, epoxy equivalent: 1509g / mol), "X-24-9590" (weight average molecular weight: 13,700, reactive functional group: epoxy group, alkane bonded to silicon atom Oxy: methoxy, epoxy equivalent: 592 g / mol) and the like.

The content of the silane coupling agent (C) is preferably 0.01 to 0.3 parts by weight, more preferably 0.03 to 0.25 parts by weight, and still more preferably 0.05 to 0.15 parts by weight relative 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 long-term reworkability decreases, or the silane coupling agent (C) oozes out, and the durability tends to decrease.

In addition, as long as the effect of the present invention is not impaired, a silane coupling agent other than the silane coupling agent (C) used in the present invention may be used. If the content of the silane coupling agent is too large, bleeding may occur and durability may be reduced. The tendency is, specifically, 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, and still more preferably 0.2 parts by weight or less based on 100 parts by weight of the acrylic resin (A).

<Crosslinking agent (D)> Examples of the crosslinking agent (D) used in the present invention include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and melamine-based crosslinking agents. Crosslinking agent, aldehyde-based crosslinker, amine-based crosslinker, metal chelate-based crosslinker.

Examples of the isocyanate-based crosslinking agent include toluene diisocyanate compounds such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; 1,3-benzenedimethyl diisocyanate, and 1,4- Benzyl diisocyanate compounds such as xylylene diisocyanate, tetramethylxylylene diisocyanate; aromatic isocyanate compounds such as 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate; hexamethylene Diisocyanates, isophorone diisocyanates, adducts of these isocyanate compounds and polyol compounds such as trimethylolpropane, biuret bodies or isocyanurate bodies of these polyisocyanate compounds, and the like.

Examples of the epoxy-based crosslinking agent include bisphenol A and epichlorohydrin-type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and glycerin dicyclo Oxypropyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether Ether, neopentaerythritol polyglycidyl tetraol, diglycerol polyglycidyl ether, and the like.

Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate , N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxyamidoamine), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxyl group) Amidine)).

Examples of the melamine-based crosslinking agent include hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, and hexapentoxymethyl. Melamine, hexahexyloxymethyl melamine, melamine resin, etc.

Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succinaldehyde, malealdialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, and benzaldehyde.

Examples of the amine-based crosslinking agent include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, and triethylene Tetraamine, isophorone diamine, amine resin, polyamine, etc.

Examples of the metal-based crosslinking agent include acetone or acetoacetate of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Acetoacetyl ester coordination compounds and the like. The said crosslinking agent (D) can be used individually or in combination of 2 or more types.

Among the above-mentioned crosslinking agents (D), an isocyanate-based crosslinking agent is preferred from the viewpoint of improving the adhesiveness with a substrate or the reactivity with an acrylic resin. Among isocyanate-based cross-linking agents, toluene diisocyanate-based cross-linking agents are preferred, and the viewpoint of a good balance between compatibility with resins and durability is preferred, and 2,4-toluene diisocyanate and trihydroxy are preferred. Addition of methylpropane.

The content of the cross-linking agent (D) is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably 1 to 3 parts by weight based on 100 parts by weight of the acrylic resin (A). If the content of the cross-linking fluorene (D) is too small, the durability tends to be easily reduced, and if it is too large, the stress relaxation property is reduced, the substrate tends to warp, or it takes a long time to mature.

In addition, the adhesive composition for a polarizing plate of the present invention may be blended with a resin component, an acrylic monomer, or a polymerization inhibitor, an antioxidant, an anticorrosive agent, and a cross-linking agent within a range that does not impair the effects of the present invention. Various additives such as crosslinking accelerators, radical generators, peroxides, radical scavengers, metals, and resin particles. In addition to the above, a small amount of impurities and the like contained in the manufacturing raw materials and the like of the constituents of the adhesive composition for polarizing plates may be contained.

The content of the other components is preferably 5 parts by weight or less, more preferably 1 part by weight or less, and still more preferably 0.5 part by weight or less based on 100 parts by weight of the acrylic resin (A). If the content is too large, the compatibility with the acrylic resin (A) tends to decrease, and the durability tends to decrease.

By mixing the acrylic resin (A), the lithium salt (B), the silane coupling agent (C), the cross-linking agent (D), and other components as required, the adhesive for polarizing plates of the present invention can be obtained.组合 物。 Composition. In addition, the mixing method is not particularly limited, and various methods such as a method of mixing the components at one time or a method of mixing the remaining components at once or sequentially after mixing arbitrary components can be adopted.

In addition, the adhesive composition for a polarizing plate of the present invention can be made into an adhesive by crosslinking it with a cross-linking agent (D), and formed by laminating it on a polarizing plate (optical laminate). The polarizer uses an adhesive layer composed of an adhesive to obtain a polarizer with an adhesive layer. The above-mentioned polarizing plate with an adhesive layer is preferably provided with a release film on the side of the adhesive layer opposite to the polarizing plate.

As for the manufacturing method of the above-mentioned polarizing plate with an adhesive layer, there are: [1] After the adhesive composition for a polarizing plate is coated on a polarizing plate and dried, a release sheet is attached, and the film is bonded at room temperature (23 ° C) And a method of performing treatment by at least one of heating and heating; [2] coating the release sheet with an adhesive composition for a polarizing plate and drying it, and then bonding the polarizing plate to each other at normal temperature and in a heated state; At least one of them is subjected to aging and a treatment method. Among these methods, the method of [2] is preferable, and the method of ripening at a normal temperature state is preferable from the viewpoint of not damaging the substrate and the viewpoint of excellent substrate adhesion.

Regarding this maturation process, the reaction time for chemical cross-linking of the adhesive composition for polarizing plates is performed in order to achieve a balance of the properties of the adhesive. As for the maturation conditions, the temperature is usually from ordinary temperature to 70 ° C, and the time is usually It is 1 to 30 days, and specifically, it can be performed under conditions such as 1 to 20 days at 23 ° C, 3 to 10 days at 23 ° C, and 1 to 7 days at 40 ° C.

When coating the above-mentioned adhesive composition for polarizing plates, it is preferable to apply the adhesive composition for polarizing plates by diluting with a solvent, and the dilution concentration is preferably 5 to 60% by weight based on the solid content concentration, particularly suitable It is 10 to 30% by weight. The solvent is not particularly limited as long as it dissolves the adhesive composition for polarizing plates. For example, methyl acetate, ethyl acetate, methyl ethyl acetate, ethyl ethyl acetate, and the like can be used. Solvents, ketone solvents such as acetone, methyl ethyl ketone, 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 suitably used.

In addition, the application of the above-mentioned adhesive composition for polarizing plates can be performed by a conventional method such as roll coating, die coating, gravure coating, notch coating, and screen printing.

In addition, the thickness of the adhesive layer in the obtained polarizing plate with an adhesive layer is preferably 5 to 200 μm, more preferably 10 to 100 μm, and further preferably 10 to 30 μm. If the thickness of the adhesive layer is too thin, the adhesive for polarizing plates does not have sufficient stress relaxation properties and the durability tends to decrease. If the thickness of the adhesive layer is too thick, moisture infiltration tends to increase and the wet heat durability tends to decrease. .

Regarding the gel fraction of the adhesive layer manufactured by the above method, the viewpoint of durability performance and suppression of reduction in polarization is preferably 30 to 95%, more preferably 40 to 90%, and still more preferably 60 to 90%. If the gel fraction is too low, satisfactory durability may not be obtained, or the reworkability may decrease, and if it is too high, it may tend to float or peel.

The above-mentioned gel fraction is used as an index of the degree of cross-linking (degree of hardening), and is calculated, for example, by the following method. That is, by selecting an adhesive sheet obtained by forming an adhesive layer on a base material to take an adhesive, the adhesive was coated with a 200-mesh metal mesh made of SUS, and immersed in ethyl acetate maintained at 23 ° C for 24 hours. After the hour, the weight percentage of the insoluble adhesive component remaining in the metal mesh was taken as the gel fraction. In addition, when the gel fraction of the adhesive is adjusted within the above range, it can be achieved by adjusting the type and amount of the crosslinking agent (D).

The adhesive layer produced by the above method has a proper tackiness when touched with a finger, and has good wettability when actually attached to an adherend, and tends to improve workability.

The polarizing plate with an adhesive layer of the present invention is a person who directly or has a release sheet peels off the release sheet, then attaches the adhesive layer to a glass substrate, and supplies it to, for example, a liquid crystal display panel.

The initial adhesive force of the adhesive for polarizing plates of the present invention is appropriately determined according to the material of the adherend, for example, when it is attached to a glass substrate, it should preferably have an adhesive force of 0.2N / 25mm to less than 15N / 25mm, more preferably It is 0.5N / 25mm to less than 10N / 25mm, and more preferably 1N / 25mm to less than 5N / 25mm.

In addition, the long-term adhesion (long-term reworkability) of the adhesive for polarizing plates of the present invention is appropriately determined according to the material of the adherend, for example, when it is attached to a glass substrate such as a liquid crystal cell, the adhesion after 20 days of adhesion The force should have an adhesive force below 20N / 25mm, more preferably below 15N / 25mm, and even more preferably below 10N / 25mm.

The adhesive force is calculated as follows. For a polarizing plate with an adhesive layer, the width is cut to 25 mm, the release film is peeled off, and the side of the adhesive layer is pressed against an alkali-free glass plate ("EAGLE XG" manufactured by Corning Corporation), and the polarizing plate and glass are laminated. board. Then, after performing an autoclave treatment (50 ° C. × 0.5 MPa × 20 minutes), and leaving it in a 23 ° C. × 50% RH environment for 20 days, a peeling test was performed at a peeling angle of 180 ° and a peeling speed of 300 mm / minute.

In terms of the antistatic performance of the polarizer with the adhesive layer manufactured by the above method, after the polarizer with the adhesive layer was manufactured, it was left to stand in a 23 ° C × 50% RH environment for 24 hours, and then the adhesive was peeled off. Layer of the release film, using the surface resistivity measuring device described below to measure the surface resistance value of the adhesive layer to obtain the "initial surface resistance 値", which is preferably less than 1 × 10 ¹² Ω / □, more preferably Up to 5 × 10 ¹¹ Ω / □, further preferably less than 1 × 10 ¹¹ Ω / □. If the initial surface resistance value is too high, there is a tendency that the polarizing plate is electrified due to friction with the backlight of the liquid crystal display panel and the like, resulting in poor display.

The adhesive composition for a polarizing plate of the present invention can obtain an excellent adhesive with excellent long-term reworkability, good durability, and good antistatic performance balance, and can be used as an adhesive for a polarizing plate to which a polarizing plate and a glass substrate are bonded. The agent system is useful.

Examples of the protective film constituting the polarizing plate include a triethyl cellulose cellulose film, an acrylic film, a polyethylene film, a polypropylene film, a cycloolefin film, and the like. For a polarizing plate using any protective film The invention is also suitable for use. [Example]

Hereinafter, the present invention will be described more specifically with examples, but the present invention is not limited to the following examples without departing from the gist thereof. In addition, "part" and "%" in the example mean the weight basis.

First, various acrylic resins (A) were prepared as described below. The measurement of the weight-average molecular weight and the degree of dispersion of the acrylic resin was performed according to the method described above.

<Preparation of acrylic resin (A)> [Production of acrylic resin (A-1)] In a 4-necked round-bottomed flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, acrylic acid (a1) was added. 5 parts, 84.4 parts of n-butyl acrylate (a2), 0.6 parts of 2-hydroxyethyl acrylate (a3), 10 parts of benzyl acrylate (a4), 48 parts of ethyl acetate, 42 parts of acetone, as polymerization initiators 0.013 parts of azobisisobutyronitrile (AIBN) began to react. After the AIBN ethyl acetate solution was appropriately dropped, the reaction was carried out at reflux temperature for 3.25 hours, and then diluted with ethyl acetate to obtain an acrylic resin ( A-1) Solution (21.2% solids, viscosity 8,900 mPa ･ s / 25 ° C, weight average molecular weight 1.41 million, dispersion 3.7).

[Production of acrylic resin (A'-1)] A 4-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer was charged with 1 part of acrylic acid (a1) and n-butyl acrylate (a2). 88.4 parts, 0.6 parts of 2-hydroxyethyl acrylate (a3), 10 parts of benzyl acrylate (a4), 48 parts of ethyl acetate, 42 parts of acetone, and azobisisobutyronitrile (AIBN) as a polymerization initiator ) 0.013 parts, the reaction was started, and in a state where the AIBN ethyl acetate solution was appropriately dropped, the reaction was carried out at reflux temperature for 3.25 hours, and then diluted with ethyl acetate to obtain an acrylic resin (A'-1) solution (solid Ingredients: 22.9%, viscosity: 10,250mPa ･ s / 25 ° C, weight average molecular weight: 1.38 million, dispersion: 3.7).

[Production of acrylic resin (A'-2)] In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, 3 parts of acrylic acid (a1) and n-butyl acrylate (a2) were added. 86.4 parts, 0.6 parts of 2-hydroxyethyl acrylate (a3), 10 parts of benzyl acrylate (a4), 48 parts of ethyl acetate, 42 parts of acetone, and azobisisobutyronitrile (AIBN) as a polymerization initiator ) 0.013 parts, the reaction was started, and in a state where the AIBN ethyl acetate solution was appropriately added dropwise, the mixture was reacted at reflux temperature for 3.25 hours, and then diluted with ethyl acetate to obtain an acrylic resin (A'-2) solution (solid content 22.6%, viscosity 10,000mPa ･ s / 25 ℃, weight average molecular weight 1.44 million, dispersion 3.5).

Table 1 shows the composition (parts by weight) of the monomers, the weight-average molecular weight of the obtained acrylic resin, and the degree of dispersion in each production example.

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

<Lithium salt (B)> The following compounds were prepared as a lithium salt (B). (B-1): Lithium bistrifluoromethanesulfonylimide and tetraethylene glycol dimethyl ether ("Sankonol TGR" (56%) manufactured by Sanko Chemical Co., Ltd.)

<Silane coupling agent (C)> The following was prepared as a silane coupling agent (C). The weight average molecular weight of the silane coupling agent (C) was measured in accordance with the method described above. In addition, for reactive functional groups, alkoxy groups bonded to silicon atoms, alkoxy groups bonded to silicon atoms, epoxy equivalents, or mercapto equivalents, catalog values are used unless otherwise specified. (C-1): "X-24-9579A" manufactured by Shin-Etsu Chemical Industry Co., Ltd. (weight average molecular weight: 2,370, reactive functional group: mercapto group, alkoxy group bonded to silicon atom: methoxy group, bond to silicon atom Amount of alkoxy group: 18.4% (measurement 値), thiol equivalent: 311g / mol (measurement 値)) (C-2): "X-24-9589" (weight average molecular weight: 4,700, Reactive functional group: epoxy group, alkoxy group bonded to silicon atom: ethoxy group, amount of alkoxy group bonded to silicon atom: 14.5% (measured by 値), epoxy equivalent: 1,509 g / mol ( Measurement 値)) (C-3): "X-24-9590" (weight average molecular weight: 13,700, reactive functional group: epoxy group, alkoxy group bonded to silicon atom: methoxy group, and silicon atom Amount of bonded alkoxy group: 9.5%, epoxy equivalent: 592g / mol)

In addition, the amount of alkoxy groups and thiol groups bonded to the silicon atom of the silane coupling agent (C-1) "X-24-9579A" and the silane coupling agent (C-2) "X-24-9589" The equivalent or epoxy equivalent is measured by the following method, and the alkoxy group content and the mercapto equivalent or epoxy equivalent of the silicon atom bond are calculated. 1. Measure about 50 mg of the sample into a vial, and add 1 mL of deuterated chloroform to dissolve it to prepare a 5% (w / v) chloroform solution. This was put into a sample tube for NMR measurement, and ¹ HNMR measurement was performed under the following conditions. ≪Measurement conditions≫ Measuring device: AscendTM400 made by Bruker Co., Ltd .: Cryo detector Pulse program: Single-pulse measurement temperature: 23 ° C (296K) Accumulated number: 16 pulse delay time: 10sec 2. Alkyl oxide bonded to silicon atom The calculation of the basis weights shows the ¹ HNMR spectra of "X-24-9579A" and "X-24-9589" in Figs. 1 and 2 respectively. First, the signals A to E of "X-24-9579A" in Figure 1 are assigned to A (3.7ppm): ethylene oxide chain, B (3.5ppm): methoxy, C (3.4ppm) : Ethylene oxide chain terminal methoxy group, D (2.5 ppm, 1.7 ppm, 1.3 ppm, 0.8 ppm): mercapto group, E (0.2 ppm): methyl group, and the bond with the silicon atom is obtained from the integrated value of these signals The amount of alkoxy and the equivalent of mercapto. Then, the signals A to F of the ¹ HNMR spectrum of "X-24-9589" in FIG. 2 are assigned to A (6.2, 6.0 ppm): propyleneoxy, B (3.6 ppm): ethylene oxide, respectively. Chain, C (3.4 ppm): ethylene oxide chain terminal methoxy, D (3.1, 2.8, 2.6 ppm): epoxy, E (1.2 ppm): ethoxy, F (0.1 ppm): methyl From the integrated values of these signals, the amount of alkoxy groups and epoxy equivalents bonded to the silicon atom can be obtained. The number of organic substituents (mercapto, epoxy, and methyl) is X, the number of alkoxy (methoxy, ethoxy, and propyleneoxy) is R, and the main chain (-SiO-) system contains ( X + R) / 2.

In addition, as the silane coupling agent other than the silane coupling agent (C) used in the present invention, the following were prepared. (C'-1): "X-41-1810" (weight average molecular weight: 640, reactive functional group: mercapto group, alkoxy group bonded to silicon atom: methoxy group, and silicon atom) manufactured by Shin-Etsu Chemical Industry Co., Ltd. Amount of bonded alkoxy group: 30%, mercapto equivalent 450g / mol) (C'-2): 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., "KBM-403", Molecular weight: 236.6, alkoxy group amount: 39% (calculated 値), reactive functional group: epoxy group, epoxy equivalent: 236.6 g / mol (calculated 値), alkoxy group: methoxy group) In addition, regarding ( The amount of alkoxy groups in C'-2) is a value obtained by dividing the weight of a methoxy group by the molecular weight (the number of methoxy groups: 3, the weight of one methoxy group: 31, and the molecular weight: 236.6). The epoxy equivalent is calculated as a molecular weight of 1 mol relative to the epoxy group.

<Crosslinking agent (D)> The following are prepared as a crosslinking agent. (D-1): Adduct of toluene diisocyanate trimethylolpropane ("Coronate L55E" manufactured by Tosoh Corporation)

<Examples 1 to 3 and Comparative Examples 1 to 6> Each of the blended components prepared and prepared as described above was blended as shown in Table 2 below to obtain an adhesive composition for a polarizing plate. Further, the adhesive composition for a polarizing plate was prepared with ethyl acetate to a solid content concentration of 12.5%, to prepare an adhesive composition for a polarizing plate.

【Table 2】

[Production of polarizing plate with adhesive layer [I]] The obtained adhesive composition for polarizing plate was applied to a 38 μm polyester separator (Mitsui Chemicals Tohcello) so that the thickness after drying was 20 μm. Inc., SP-01BU), after drying at 100 ° C for 3 minutes, the triacetam cellulose (TAC) film was bonded to the TAC surface of a polarizing plate laminated on one side, at 23 ° C × 50% The aging process was carried out for 10 days to obtain a polarizing plate with an adhesive layer [I].

Using the obtained polarizing plate [I] with an adhesive layer, the gel fraction, initial and long-term reworkability (adhesive force), antistatic performance, and durability of the adhesive layer were evaluated in the following manner. The results are shown in Table 3.

<Gel fraction> 80 mg of the adhesive layer was scraped from the polarizing plate [I] with the adhesive layer obtained above, and the adhesive layer obtained by the scraping was covered with a 200-mesh metal mesh made of SUS and kept at After immersing in 200 ml of ethyl acetate solvent at 23 ° C for 24 hours, the metal mesh was taken out and dried in a vacuum dryer at 100 ° C for 2 hours. Let the weight percentage of the insoluble adhesive component remaining in the metal mesh after drying be the "gel fraction".

<Initial reworkability> The polarizing plate [I] with an adhesive layer obtained above was cut to a width of 25 mm, the separator was peeled off, and the adhesive layer was pressed against an alkali-free glass ("EAGLE XG" manufactured by Corning Corporation: thickness 1.1 mm ), Press it back and forth twice with a 2kg roller from above to make it adhere, and then perform autoclave treatment (0.5Mpa × 50 ° C × 20 minutes). After standing for 24 hours in an environment of 23 ° C × 50% RH, it is evaluated for peeling. Adhesion when peeling at an angle of 180 ° and a peeling speed of 300 mm / min. (Evaluation criteria) ･ ･ ･ ･ ･ ･ 0.1N / 25mm or more, less than 5N / 25mm ○ ･ ･ ･ 5N / 25mm or more, less than 10N / 25mm × ･ ･ ･ 10N / 25mm or more

<Long-term reworkability> The polarizing plate [I] with the adhesive layer obtained above was cut to a width of 25 mm, the separator was peeled off, and the adhesive layer was pressed against an alkali-free glass ("EAGLE XG" manufactured by Corning Corporation: thickness 1.1 mm ), Press it back and forth twice with a 2kg roller from above to make it adhere, and perform an autoclave treatment (0.5Mpa × 50 ° C × 20 minutes). After standing in a 23 ° C × 50% RH environment for 20 days, it is evaluated for peeling. Adhesion when peeling at an angle of 180 ° and a peeling speed of 300 mm / min. (Evaluation criteria) ･ ･ ･ ･ ･ ･ 10N / 25mm or less ○ ･ ･ ･ 10N / 25mm or more to 15N / 25mm △ ･ ･ ･ 15N / 25mm or more to 20N / 25mm or more ･ ･ ･ 20N / 25mm or more

<Antistatic performance> After the above polarizing plate [I] with an adhesive layer was allowed to stand in an environment of 23 ° C × 50% RH for 24 hours, the separator of the adhesive layer was removed, and a surface resistivity measuring device (Mitsubishi Chemical Analytical company, device name "Hiresta-UP MCP-HT450") was used to measure the surface resistivity of the adhesive layer. The evaluation criteria are as follows. (Evaluation criteria) ○ ･ ･ ･ Below 2.0 × 10 ¹¹ Ω / □ △ ･ ･ ･ 2.0 × 10 ¹¹ Ω / □ or more, but less than 1.0 × 10 ¹² Ω / □ × ･ ･ ･ 1.0 × 10 ¹² Ω / □ the above

<Durability> The separator of the polarizing plate [I] with an adhesive layer is peeled off, and the side of the adhesive layer is pushed to an alkali-free glass plate (EAGLE XG, manufactured by Corning Corporation). After autoclave treatment (50 ° C × 0.5 MPa × 20 minutes), the following endurance test was performed, and evaluation was performed from the presence or absence of blistering, peeling, and the like as follows. The size of the test piece used in the test was 20 cm x 15 cm (pressed). In addition, the presence or absence of blistering and peeling was observed using a magnifying glass (manufactured by Tokai Industries Co., Ltd. PEAK LUPE 15 ×). (1) Heat resistance test The endurance test at 80 ° C for 500 hours was evaluated as follows. (2) Moisture and heat resistance test The durability test at 60 ° C x 90% RH x 500 hours was evaluated as follows. (3) Cold and hot shock test The durability test was repeated by repeating a cycle of -30 ° C and 80 ° C for 30 minutes each for 500 hours as follows. (4) High humidity and heat resistance test The durability test at 85 ° C x 85% RH x 500 hours was evaluated as follows. (5) High-cold hot shock test The durability test was repeated by repeating a cycle of -40 ° C and 85 ° C for 30 minutes each for 500 hours as follows. (Evaluation criteria) No floating, peeling, or blistering was observed at all on the polarizing plate ○ 浮 No floating or peeling was observed on the polarizing plate, but blistering was observed × ･ ･ ･ on the polarizing plate Observation of lifting and flaking

【table 3】

From the results in Table 3, it can be seen that in the adhesive composition for polarizing plates obtained by using an acrylic resin having a relatively large content of carboxyl group-containing monomers and a lithium salt as an antistatic agent, a silane coupling having a specific molecular weight is used. Examples 1 to 3 as the silane coupling agent satisfy the antistatic performance, have excellent durability, have moderate initial adhesion, and have excellent long-term reworkability.

In contrast, Comparative Examples 1 and 2 using a silane coupling agent having a molecular weight smaller than the specific molecular weight of the present invention show that although the durability is satisfied, the long-term reworkability is poor. In addition, Comparative Examples 3 to 6 using acrylic resins having a small amount of carboxyl-containing monomers were found to have long-term reworkability but unsatisfactory durability.

In the above-mentioned embodiment, a specific form of the present invention is shown, but the above-mentioned embodiment is merely a mere example and has no limited meaning. Various changes apparent to those skilled in the art are intended to be included within the scope of the present invention. [Industrial availability]

When 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 manufacturing a liquid crystal display device, it exhibits excellent heavy industry over a long period of time. It is also excellent in durability and antistatic performance under more severe conditions, so it is used as an adhesive for bonding optical components to displays or optical components constituting the display, especially for bonding polarizing plates. Adhesives for polarizing plates such as glass substrates of liquid crystal cells are useful.

[Figure 1] The ¹ HNMR spectrum of the silane coupling agent "X-24-9579A" is shown.

[Figure 2] The ¹ HNMR spectrum of the silane coupling agent "X-24-9589" is shown.

Claims (8)

An adhesive composition for a polarizing plate, comprising: an acrylic resin (A), a lithium salt (B), and one or more silanes each containing a reactive functional group in a structure and an alkoxy group bonded to a silicon atom. A coupling agent (C), wherein the acrylic resin (A) has a structural unit derived from a carboxyl group-containing monomer (a1), and the acrylic resin (A) has a structural unit derived from the carboxyl group-containing monomer (a1) The content of the structural unit is 4 to 10% by weight, and the weight average molecular weight of the silane coupling agent (C) is 2,000 or more. For example, the adhesive composition for a polarizing plate according to item 1 of the application, wherein the content of the lithium salt (B) is 0.3 to 8 parts by weight based on 100 parts by weight of the acrylic resin (A). For example, the adhesive composition for a polarizing plate according to item 1 or 2 of the application, wherein the content of the silane coupling agent (C) is 0.01 to 0.3 parts by weight based on 100 parts by weight of the acrylic resin (A). For example, the adhesive composition for a polarizing plate according to item 1 or 2 of the application, wherein the reactive functional group of the silane coupling agent (C) is a mercapto group, and the equivalent of the mercapto group is 100 to 2,000 g / mol. For example, the adhesive composition for a polarizing plate according to item 1 or 2 of the patent application range, wherein the reactive functional group epoxy group of the silane coupling agent (C) has a weight average molecular weight of 4,000 or more. For example, the adhesive composition for a polarizing plate of the first or second patent application range further includes a crosslinking agent (D). An adhesive for polarizing plates, characterized in that the adhesive composition for polarizing plates according to any one of claims 1 to 6 is crosslinked by a crosslinking agent (D). A polarizing plate with an adhesive layer is obtained by laminating an adhesive layer on a polarizing plate. The polarizing plate is characterized in that the adhesive layer contains an adhesive for a polarizing plate as in item 7 of the scope of patent application.