TW201817838A - Acrylic adhesive composition, adhesive obtained using same, polarizing plate adhesive, and image display device - Google Patents

Abstract

Provided is an adhesive composition capable of providing a superior adhesive layer having excellent resistance to whitening due to heat and humidity, excellent initial durability, and excellent storage stability (durability over time) when used as a polarizing plate adhesive for pasting together a polarizing plate and a glass substrate or the like. The acrylic adhesive composition contains an acrylic resin (A) and a silane coupling agent (B) containing at least one each of a reactive functional group and an alkoxy group in a structure, and is characterized in that the acrylic resin (A) contains 5-50 wt% of structural units 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-containing monomer, and at least one of the alkoxy groups contained in the silane coupling agent (B) is a C2-8 alkoxy group.

Description

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

The present invention relates to an acrylic adhesive composition, an adhesive obtained by using the acrylic adhesive composition, and an adhesive for polarizing plates. More specifically, the present invention relates to the formation of an acrylic adhesive under moist heat conditions. Acrylic adhesive composition of an adhesive with excellent moisture and whitening resistance and excellent storage stability of the adhesive layer.

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

In order to adhere the protective film to a polarizer, an adhesive containing a polyvinyl alcohol-based resin is preferably used. Specifically, it is an aqueous solution obtained by blending a polyvinyl alcohol-based resin with a crosslinking agent. The polarizer is coated on a polarizer and a protective film is laminated, and then heated and dried to produce a polarizing plate. In the above manufacturing steps of the polarizing plate, it is preferable that the moisture contained in the adhesive penetrates the protective film. The protective film has hitherto used a triethyl cellulose cellulose film (TAC film) with high moisture permeability.

However, in recent years, from the viewpoint of dimensional stability and durability, TAC films have been gradually replaced with olefin-based films, especially cycloolefin-based films (COP films) as protective films for polarizing plates. When such a COP film is used, although the moisture and heat resistance of the polarizing plate is improved, the liquid crystal display device obtained by bonding the polarizing plate to the liquid crystal cell through an adhesive is liable to cause adhesion when exposed to a hot and humid environment. The problem of whitening of the agent layer. The reason is that if it is left under humid and hot conditions for a long time, moisture will slowly penetrate into the adhesive layer, and when it returns to normal temperature, the moisture will condense in the adhesive layer, but the moisture permeability of the COP film is low, which inhibits This releases the moisture in the adhesive layer.

In addition, for the adhesive for bonding the polarizing plate and the liquid crystal cell, durability such as heat resistance and humidity and heat resistance is required. However, in a humid and hot environment, moisture will penetrate into the adhesive layer and adhere to the glass substrate. Since it is lowered, there is a problem that the polarizing plate partially floats or peels off from the glass substrate. In order to improve the adhesion between the glass substrate and the adhesive layer, it is generally known to contain a silane coupling agent. The silane coupling agent is hydrolyzed to silanol by water, and reacts with and binds to hydroxyl groups on the glass surface, thereby improving the adhesion.

For an adhesive having excellent moisture and heat resistance, for example, Patent Document 1 describes that an acrylic adhesive using an acrylic resin obtained by copolymerizing more hydroxyl monomers than usual is excellent in moisture and whitening resistance.

[Prior Art Document] [Patent Document] [Patent Document 1] Japanese Patent Laid-Open No. 2013-213203

(Problems to be Solved by the Invention) The adhesive described in Patent Document 1 has a high content of hydroxy monomers (monomers containing polar groups) in acrylic resins and is excellent in moist heat and whitening resistance. On the other hand, it is highly hydrophilic. Even under normal circumstances, moisture still easily penetrates into the adhesive layer.

Here, when the image display device is manufactured, an adhesive layer is usually provided on the release-treated film, and an adhesive layer on the opposite side to the release film is attached to the polarizing plate, and attached adhesion is provided. The polarizing plate of the adhesive layer is produced by laminating the release film to attach the adhesive layer and the glass substrate of the liquid crystal cell when the polarizing plate is bonded to the liquid crystal cell.

Therefore, if the adhesive described in Patent Document 1 is used as an adhesive for polarizing plates, although the moisture-heat whitening resistance and initial durability are good, the polarizing plate with the adhesive layer is manufactured until it is bonded to the glass of the liquid crystal cell. During the storage period up to the substrate, the silane coupling agent is slowly hydrolyzed due to the moisture contained in the adhesive layer, and the alkoxy group that contributes to the adhesion to the glass is reduced by a condensation reaction or the like. The adhesion between the polarizing plate and the glass substrate at the time of bonding is reduced (durability is reduced over time), that is, the storage stability of the adhesive layer is reduced.

Under such a background, the present invention provides moist heat whitening resistance, excellent initial durability, and storage stability even when used as an adhesive for a polarizing plate where a polarizing plate and a glass substrate are bonded. (Durability) is also an acrylic adhesive composition having an excellent adhesive layer. (The way to solve the problem)

The inventors of this case worked hard on this situation, and found that in the acrylic adhesive composition containing an acrylic resin and a silane coupling agent, acrylic acid containing a large amount of structural units derived from a monomer containing a polar group was used. Series resin, further blended with a silane coupling agent of a specific alkoxy group, whereby the whitening of the adhesive layer can be suppressed even under hot and humid conditions, and an adhesive having excellent storage stability can be obtained.

That is, the first gist of the present invention is an acrylic adhesive composition containing an acrylic resin (A) and a silane coupling agent having at least one reactive functional group and an alkoxy group in the structure, respectively. (B), characterized in that the acrylic resin (A) contains 5 to 50% by weight of at least one selected from the group consisting of a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer; In the acrylic resin having a structural unit of a polar monomer (a1), at least one of the alkoxy groups contained in the silane coupling agent (B) is an alkoxy group having 2 to 8 carbon atoms. The second aspect of the present invention is an adhesive obtained by crosslinking the acrylic adhesive composition of the first aspect with a crosslinking agent (C), and the third aspect is the use of the adhesive of the second aspect. The fourth gist of the formed polarizing plate adhesive is an image display device in which the polarizing plate and the liquid crystal cell are bonded with the bonding agent as in the second gist. (Effect of the invention)

The present invention is an acrylic adhesive composition containing an acrylic resin (A) and a silane coupling agent (B) having at least one reactive functional group and an alkoxy group in the structure, respectively. The resin (A) contains 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-containing monomer. Acrylic resin, at least one of the alkoxy groups contained in the silane coupling agent (B) is an alkoxy group having 2 to 8 carbon atoms. Therefore, even when the adhesive obtained by using the acrylic adhesive composition of the present invention is used as an adhesive for bonding a polarizing plate and a glass substrate, the adhesive has excellent durability and wet heat whitening resistance, and the adhesive The storage stability of the layer is also excellent. Therefore, by using this acrylic adhesive composition, an image display device that exhibits excellent optical characteristics without degrading performance can be obtained even when used under humid and hot conditions, such as in more severe environments. Especially when using any of TAC film and COP film as a protective film for polarizing plates, the adhesive layer has excellent moisture and heat whitening resistance and the storage stability of the adhesive layer is also excellent. Splices are very useful.

When the said polar group containing monomer (a1) is a hydroxyl containing monomer, it will be more excellent in moist-heat whitening resistance, and its adhesive physical property will also be excellent.

When the alkoxy group having 2 to 8 carbon atoms contained in the silane coupling agent (B) is an ethoxy group, the durability and storage stability of the adhesive layer are more excellent.

When the alkoxy group contained in the silane coupling agent (B) is an ethoxy group and a methoxy group, the durability and storage stability of the adhesive layer are more excellent.

When the silane coupling agent (B) contains an alkoxy group in an amount of 5% by weight or more, the durability and storage stability of the adhesive layer are more excellent, and the reworkability is also excellent.

When the reactive functional group equivalent of the said silane coupling agent (B) is 50-1000 g / mol, durability and reworkability will be more excellent.

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

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

<Acrylic resin (A)> The acrylic resin (A) used in the present invention is an acrylic resin containing 5 to 50% by weight of a structural unit derived from a polar group-containing monomer (a1). For example, the acrylic resin will contain 5 A copolymerization component of ~ 50% by weight of a polar group-containing monomer (a1) is obtained by copolymerization. The copolymerization component of the acrylic resin (A) may contain an alkyl (meth) acrylate monomer (a2) and other copolymerizable ethylenically unsaturated monomers (a3) as necessary.

The polar group-containing monomer (a1) is at least one selected from a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer.

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

Among the above-mentioned hydroxyl-containing monomers, considering the viewpoint of excellent reactivity with a crosslinking agent and the viewpoint of improving moist heat whitening resistance, monomers containing a primary hydroxyl group are preferable, and 2-hydroxyethyl acrylate and 4-acrylate Hydroxybutyl ester, di (meth) acrylate, and the like are preferred because they have few impurities and are easily manufactured.

In addition, the hydroxyl-containing monomer used in the present invention is preferably one in which the content of di (meth) acrylate is 0.5% by weight or less, more preferably 0.2% by weight or less, and particularly preferably 0.1% by weight or less. . Specifically, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxypropyl acrylate are preferable.

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

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

The above amine group-containing monomers include, for example, monomers containing a primary amine group such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate, and tert-butylaminoethyl (meth) acrylate Tertiary amine-containing monomers such as esters, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate Based monomers, etc. Among the above-mentioned amine group-containing monomers, from the viewpoints of storage stability of the resin solution and the effect of promoting crosslinking, a monomer containing a third-order amine group is preferable, and dimethylaminoethyl (meth) acrylate is particularly preferable.

The amidino group-containing monomers are, for example, methoxymethyl (meth) acrylamido, ethoxymethyl (meth) acrylamido, propoxymethyl (meth) acrylamido, Alkoxyalkyl (methyl) such as isopropoxymethyl (meth) acrylamide, n-butoxymethyl (meth) acrylamide, isobutoxymethyl (meth) acrylamide ) Acrylamide-based monomers; dialkyl (meth) acrylamide-based monomers such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide; (meth) acrylamine Amine; N- (hydroxymethyl) acrylamide; (meth) acrylamide Porphyrin, etc.

Among the above-mentioned amide-containing monomers, from the viewpoint of stability of the resin solution and the viewpoint of suppressing the movement of the antistatic agent, alkoxyalkyl (meth) acrylamidoamine-based monomers, dialkyl (methyl A) acrylamide-based monomer is preferred.

Among the above-mentioned polar group-containing monomers (a1), the viewpoints of moist-heat whitening resistance and adhesive physical properties are considered. The monomers containing hydroxyl groups and the monomers containing carboxyl groups are ideal. The viewpoint of excellent moist-heat whitening resistance is considered. From the viewpoint of excellent properties, a hydroxyl-containing monomer is preferred. Moreover, the said polar group containing monomer (a1) can be used individually or in combination of 2 or more types.

The content of the polar group-containing monomer (a1) (the total content when two or more types are used in combination) is 5 to 50% by weight, especially 6 to 30% by weight, and more preferably 7 to 7% by weight based on the entire copolymerization component. ~ 25% by weight, particularly preferably 8 ~ 20% by weight. If the content is too small, the moist-heat whitening resistance is reduced, and if it is too large, the storage stability when the adhesive is made is reduced.

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

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

The content of the (meth) acrylic acid alkyl ester monomer (a2) is preferably 20 to 95% by weight, more preferably 40 to 94% by weight, and still more preferably 45 to 93% by weight relative to the entire copolymerization component. %, Particularly preferably 50 to 92% by weight. If the content is too small, there is a tendency that the physical properties of the adhesive are not easily balanced, and if it is too large, the moist heat and whitening properties tend to decrease.

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

Among these, considering that the adjustment of the refractive index and the adjustment of birefringence are easy to perform, monomers containing an aromatic ring are preferable (preferably benzyl (meth) acrylate, phenoxy (meth) acrylate) Ethyl ester, phenoxy diethylene glycol (meth) acrylate), considering the adjustment of the refractive index and the adjustment of the birefringence, it is easy to perform, and it has excellent adhesion to low-polar adherends (such as cycloolefins) From the viewpoint, an alicyclic-containing monomer is preferred.

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

The acrylic resin (A) used in the present invention can be appropriately selected by appropriately selecting a polar group-containing monomer (a1), and it is more preferable to further appropriately select an alkyl (meth) acrylate-based monomer (a2) and other co-polymers. A copolymerized component of the polymerized ethylenically unsaturated monomer (a3) is polymerized to manufacture. The polymerization can be carried out in accordance with a conventionally known method such as solution radical polymerization, suspension polymerization, block polymerization, and emulsion polymerization. For example, a polymerization component containing a polar group-containing monomer (a1) and a polymerization initiator are mixed or dropped in an organic solvent, and polymerization is performed under predetermined polymerization conditions. Among these polymerization methods, solution radical polymerization and block polymerization are preferable, and solution radical polymerization is more preferable.

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

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

The acrylic resin (A) used in the present invention contains 5 to 50% by weight of a structural unit derived from a polar group-containing monomer (a1), and preferably contains 6 to 30% by weight, especially 7 to 25% by weight, particularly It is preferably 8 to 20% by weight. If the structural unit derived from the polar group-containing monomer (a1) is too small, the moisture-heat whitening resistance is reduced, and if it is too large, the reworkability and durability are reduced.

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

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

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

The glass transition temperature (Tg) of the acrylic resin (A) is preferably -80 to 0 ° C, particularly preferably -60 to -10 ° 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 is calculated using the following Fox formula. Tg: glass transition temperature (K) of acrylic resin (A) Tga: glass transition temperature (K) of homopolymer of monomer A Wa: weight fraction of monomer A Tgb: of homopolymer of monomer B Glass transition temperature (K) Wb: weight fraction of monomer B Tgn: glass transition temperature of homopolymer of monomer N (K) Wn: weight fraction of monomer N (Wa + Wb + ∙ ∙ + Wn = 1)

That is, the glass transition temperature (Tg) of the acrylic resin (A) is calculated by substituting the glass transition temperature and weight fraction of each monomer constituting the acrylic resin (A) into a homopolymer to the above-mentioned formula of Fox.値. In addition, the glass transition temperature when the monomer constituting the acrylic resin (A) is made into a homopolymer is usually measured by a differential scanning calorimeter (DSC), and a method according to JIS K7121-1987 and JIS K 6240 can be used. Perform the measurement.

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

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

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

<Silane coupling agent (B)> Generally, a silane coupling agent is an organic silicon compound containing one or more reactive functional groups and an alkoxy group in each structure. In the present invention, a silane coupling agent (B) containing at least one reactive functional group and an alkoxy group in the structure, and at least one of the alkoxy groups is an alkoxy group having 2 to 8 carbon atoms is used as the silane coupling agent (B). Essential ingredients.

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

The above-mentioned reactive functional groups include, for example, epoxy groups, (meth) acrylfluorenyl groups, mercapto groups, hydroxyl groups, carboxyl groups, amine groups, amidoamine groups, isocyanate groups, and the like. Among these, the viewpoints of durability and reworkability are considered. Epoxy group and mercapto group are ideal, especially considering the durability and storage stability, epoxy group is better.

The silane coupling agent (B) is only required if at least one of the alkoxy groups contained is an alkoxy group having 2 to 8 carbon atoms. From the viewpoint of durability and storage stability, the alkane having 2 to 8 carbon atoms is required. The oxy group is preferably an ethoxy group.

From the viewpoints of durability and storage stability, it is preferable that the silane coupling agent (B) contains both an ethoxy group and a methoxy group in the structure as the alkoxy group.

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

In consideration of preservation stability, reworkability, and durability, the silane coupling agent (B) should preferably contain more than 5% by weight of alkoxy groups in its structure, particularly preferably 5 to 80% by weight, and more preferably 15 to 70% by weight, particularly preferably 30 to 60% by weight. If the content of the alkoxy group is too small, the durability under storage stability and humidity and heat resistance tends to decrease, and if it is too large, the reworkability tends to decrease.

The silane coupling agent (B) preferably has a reactive functional group equivalent weight of 50 to 1,000 g / mol, more preferably 100 to 900 g / mol, and even more preferably 300 to 850 g / mol. If the reactive functional group equivalent is too small, reworkability tends to decrease, and if it is too large, durability under moist heat resistance tends to decrease.

In terms of the weight average molecular weight of the silane coupling agent (B), considering the viewpoint of non-volatile during drying and the viewpoint of improving reworkability, 500 to 20,000 is preferable, and 1,000 to 15,000 is more preferable, and 2,000 to 15,000 is more preferable. 14,000.

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

As for the silane coupling agent (B), it can be a monomeric organosilicon compound, or a part of the organosilicon compound can be hydrolyzed and polycondensed to obtain an oligomeric organosilicon compound such as a dimer or trimer. (Organic Siloxane Compound) From the viewpoints of reworkability and long-term storage stability, it is preferable to use an oligomeric type organic silicon compound having a dimer or more.

Silane coupling agent (B), for example: organic silicon compounds such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, organic silicon compounds, etc. Partially hydrolyzed and polycondensed oligomeric organosilicon compounds (epoxy containing polysiloxyalkoxy oligomers, etc.), or organic compounds obtained by partially modifying these organosilicon compounds with ether Epoxy-containing silane coupling agents such as silicon compounds; oligomeric organic silicon compounds (containing thiol groups) obtained by hydrolyzing and polycondensing a part of organic silicon compounds such as γ-mercaptopropyltriethoxysilane and organic silicon compounds Polysiloxyalkoxy oligomers, etc.) mercapto-containing silane coupling agents; etc.

As the silane coupling agent (B) used in the present invention, specifically, a commercially available product manufactured by Shin-Etsu Chemical Industry Co., Ltd., "X-41-1059A" (reactive functional group contained; epoxy group, alkoxy group contained) : Methoxy and ethoxy), "X-41-1805" (reactive functional group contained: mercapto, alkoxy group contained: methoxy and ethoxy), "X-41-1818" ( The reactive functional group to be contained: mercapto group, alkoxy group to be contained: ethoxy group), and the like may be sufficient. Among them, considering the viewpoint of excellent remanufacturability and storage stability, X-41-1059A is particularly preferred.

The content of the silane coupling agent (B) is preferably 0.005 to 1 part by weight relative to 100 parts by weight of the acrylic resin (A), more preferably 0.01 to 0.5 part by weight, and even more preferably 0.025 to 0.15 Parts by weight. If the content of the silane coupling agent (B) is too large, there is a tendency that the durability under heat-resistant conditions may be exuded, and if it is too small, the moisture and heat resistance may be reduced, or storage stability may be reduced.

The silane coupling agent (B) may be used alone or in combination of two or more.

In addition, a silane coupling agent other than the above-mentioned silane coupling agent (B) may be used within a range that does not impede the effects of the present invention. However, if the content of the silane coupling agent is excessive, the durability tends to decrease due to bleeding. . Therefore, the content of the silane coupling agent other than the silane coupling agent (B), specifically, is preferably 0.5 parts by weight or less, and more preferably 0.3 parts by weight or less, based on 100 parts by weight of the acrylic resin (A). , Particularly preferably 0.2 part by weight or less.

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

<Crosslinking agent (C)> The crosslinking agent (C) used in the present invention is, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, or a melamine-based crosslinking agent. Agent, aldehyde-based cross-linking agent, amine-based cross-linking agent, and metal chelate-based cross-linking agent. Among these, from the viewpoint of improving the adhesion to the substrate, it has excellent reactivity with the acrylic resin (A). From the viewpoint, it is preferable to use an isocyanate-based crosslinking agent.

The isocyanate-based crosslinking agent is, for example, 2,4-methylenephenyl diisocyanate, 2,6-methylenephenyl diisocyanate, hydrogenated methylenephenyl diisocyanate, 1,3-xylene diisocyanate, 1 , 4-xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanoxymethyl) cyclohexyl Alkane, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and adducts of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, and these polyisocyanates Compound biuret bodies, isocyanurate bodies, etc.

The above epoxy-based crosslinking agents include, for example, 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, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, neopentyl Alcohol polyglycidyl tetraol, diglycerol polyglycidyl ether and the like.

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

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

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

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

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

The said crosslinking agent (C) can be used individually or in combination of 2 or more types. Among the above-mentioned cross-linking agents (C), an isocyanate-based cross-linking agent is preferably used from the viewpoint of improving the adhesiveness with the substrate and the viewpoint of reactivity with the acrylic resin (A). Among isocyanate-based cross-linking agents, methylenediphenyl diisocyanate is ideal from the standpoint of shelf life and durability, and xylene diisocyanate or isocyanate containing nurate skeleton is preferred from the standpoint of shortening the curing time. The viewpoint of yellowing resistance is desirable. Among them, specifically, methylenephenyl diisocyanate, xylene diisocyanate, adduct of hexamethylene diisocyanate and trimethylolpropane, and isocyanurate are suitable for durability and application. The viewpoint that the balance between the period and the crosslinking speed is excellent is preferable.

The content of the cross-linking agent (C) is preferably 0.01 to 5 parts by weight relative to 100 parts by weight of the acrylic resin (A), more preferably 0.05 to 1 part by weight, and even more preferably 0.1 to 0.5 part by weight. If the content of the cross-linking agent (C) is too small, the durability tends to be reduced. If it is too large, the stress relaxation property is reduced, the substrate tends to warp, or it takes a long time to mature.

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

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

The organic salt is, for example, 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 these, from the viewpoint of compatibility with the resin and the viewpoint of corrosion prevention from the viewpoint of the ionic compound (D1), organic salts are preferable, and ammonium salts, imidazolium salts, pyridinium salts, Onium salts composed of nitrogen-containing cations, such as piperidinium salts and pyrrolidinium salts, are particularly preferably alkyl ammonium salts, and even more preferably a non-cyclic tetraalkylammonium cation and N, N-bis (trifluoromethane An ammonium salt composed of a sulfonyl) phosphonium imine anion.

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

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

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

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

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

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

The manufacturing method of the above-mentioned optical member with an adhesive layer can be enumerated as follows: [1] Applying an acrylic adhesive composition to the optical member, and drying and bonding the release sheet at room temperature (23 ° C) or adding A method of curing at least one of the conditions in a warm state to implement treatment, [2] coating an acrylic adhesive composition on a release sheet, bonding the optical member after drying, and at least one of room temperature or a warmed state The method of curing is carried out under conditions such as those described above. Among these, the method of [2] and the method of ripening at room temperature are preferable from the viewpoint of no damage to the optical member and the viewpoint of excellent adhesion to the optical member. Among the above, it is particularly effective when the optical member is a polarizing plate.

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

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

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

The gel fraction of the adhesive layer produced according to the above method, considering the durability and the viewpoint of suppressing the decline of the degree of polarization, is preferably 30 to 95% by weight, particularly preferably 40 to 85% by weight, and more preferably 60. ~ 80% by weight. If the gel fraction is too low, the reworkability tends to decrease, and if it is too high, the floating and peeling tend to occur.

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

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

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

The electrical properties of the adhesive layer obtained by using the acrylic adhesive composition of the present invention are ideal in terms of antistatic properties if the surface resistance is low, particularly preferably 5 × 10 ¹² Ω / cm ² or less, and more preferably It is 1 × 10 ¹¹ Ω / cm ² or less, and particularly preferably 5 × 10 ¹⁰ Ω / cm ² or less. If the surface resistance 値 is too high, the polarizing plate and the adhesive layer tend to be charged, and display unevenness tends to occur.

In addition, in the obtained optical member with an adhesive layer, the thickness of the dried adhesive layer should preferably be 5 to 200 μm, especially 10 to 100 μm is preferable, and 10 to 30 μm is more preferable. If the thickness of the adhesive layer is too thin, the physical properties of the adhesive tend to lack stability. If it is too thick, the amount of water infiltration from the ends will increase, and storage stability tends to decrease.

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

The initial adhesion force of the above-mentioned adhesive layer can be appropriately determined according to the material of the adherend. For example, when bonding to a glass substrate, the adhesion force below 15N / 25mm should be better, especially 0.1 ~ 12N / 25mm, and more preferably 0.5 ~ 8N / 25mm.

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

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

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

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

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

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

<Preparation of acrylic resin (A)> [Manufacture of acrylic resin (A-1)] A 4-neck round bottom flask equipped with a reflux cooler, a stirrer, a nitrogen blowing inlet, and a thermometer was charged with 2-hydroxyethyl acrylic acid. 6 parts of ester (a1), 0.7 parts of acrylic acid (a1), 73.3 parts of n-butyl acrylate (a2), 20 parts of benzyl acrylate (a3), 54.9 parts of ethyl acetate, 42 parts of acetone, as a polymerization initiator 0.013 parts of nitrogen bisisobutyronitrile (AIBN), the reaction was started, and 30 parts of ethyl acetate solution containing 0.04% AIBN was added dropwise while reacting at reflux temperature for 3.25 hours, and then diluted with ethyl acetate to obtain an acrylic resin (A -1) Solution (solid content: 20.9%, viscosity: 4,770 mPa · s / 25 ° C, acrylic resin (A-1): glass transition temperature -43 ° C, weight average molecular weight: 1.29 million, dispersion: 4.3).

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

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

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

<Silane coupling agent (B)> The following silane coupling agent (B) was prepared. The weight average molecular weight and the degree of dispersion of the silane coupling agent (B) were measured according to the methods described above. In addition, unless otherwise specified, the content of the reactive functional group, the equivalent of the reactive functional group, and the content of the alkoxy group and the alkoxy group contained in the formula are used.

(B-1): oligomeric silane coupling agent containing ethoxy group and methoxy group ("X41-1059A" manufactured by Shin-Etsu Chemical Industry Co., Ltd., containing reactive functional group: epoxy group, reactive functional group Equivalent: 350g / mol, contained alkoxy: methoxy and ethoxy, alkoxy content: 42%, weight average molecular weight: 2,270, dispersion: 1.86)

(B-2): An oligomeric silane coupling agent containing ethoxy and methoxy groups ("X41-1805" manufactured by Shin-Etsu Chemical Industry Co., Ltd., containing reactive functional group: mercapto group, reactive functional group equivalent: 800g / mol, containing alkoxy: methoxy and ethoxy, alkoxy content: 50%, weight average molecular weight: 3,450, dispersion: 1.85)

(B'-1): Silane coupling agent containing methoxy group ("KBM-403" manufactured by Shin-Etsu Chemical Industry Co., Ltd., containing reactive functional group: epoxy group, reactive functional group equivalent: 236.3 g / mol ( Calculated ii), contained alkoxy group: methoxy group, alkoxy group content: 39% (calculated ii), molecular weight: 236.3) In addition, the above reactive functional group equivalent of B'-1 is relative to epoxy Calculate the molecular weight of 1 mol. Regarding the content of alkoxy groups, fluorene obtained by dividing the weight of methoxy groups by the molecular weight (the number of methoxy groups: 3, the weight of one methoxy group: 31, and the molecular weight: 236.6).

(B'-2); Silane coupling agent containing methoxy group ("KBM-803" manufactured by Shin-Etsu Chemical Industry Co., Ltd., containing reactive functional group: mercapto group, reactive functional group equivalent: 196.4 g / mol (calculated) ), Contained alkoxy group: methoxy group, alkoxy group content: 47% (calculated 値), molecular weight: 196.4) Moreover, the reactive functional group equivalent of the above B'-2 is a molecular weight of 1 mol relative to the mercapto group Calculation. Regarding the alkoxy group content, fluorene obtained by dividing the weight of the methoxy group by the molecular weight (the number of methoxy groups: 3, the weight of one methoxy group: 31, and the molecular weight: 196.4).

(B'-3): An oligomeric silane coupling agent containing a methoxy group ("X-24-9590" manufactured by Shin-Etsu Chemical Industry Co., Ltd., containing a reactive functional group: epoxy group, functional group equivalent: 592 g / mol, contained alkoxy: methoxy, alkoxy content: 9.5%, weight average molecular weight: 13,700, dispersion: 3.44)

<Crosslinking agent (C)> The following crosslinking agents (C) are prepared. (C-1): adduct of methylphenyl diisocyanate and trimethylolpropane ("CORONATE L55E" manufactured by Tosoh Corporation: 55% active ingredient)

<Antistatic agent (D)> The following antistatic agents (D) were prepared. (D1-1): Tri-n-butylmethylammonium N, N-bis (trifluoromethanesulfonyl) fluorenimide (manufactured by 3M Corporation, "FC-4400")

<Examples 1 to 5, Comparative Examples 1 to 5> The above components (A) to (D) were blended according to the following Table 2, and the solid content concentration was adjusted to 12.5% with ethyl acetate to obtain an acrylic adhesive composition. Thing.

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

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

[Preparation of Evaluation Sample] The acrylic adhesive composition obtained above was applied to a release sheet having a thickness of 38 μm (“Lumirror SP-0138BU” manufactured by Mitsui Chemicals TOHCELLO), so that the thickness after drying was 25 μm and 100 μm. After drying at ℃ for 3 minutes, a polarizing plate composed of the following two structures was laminated on the adhesive layer on the side opposite to the release sheet, and then cured for 7 days in an environment of 23 ° C × 50% RH to obtain additional equipment. Polarizing plate for adhesive layer.

∙ Polarizer with adhesive layer [I]: TAC film 1 / PVA film (polarizing plate) / TAC film 2 / adhesive layer / release sheet Also, the above TAC film is a triethylfluorene-based cellulose film (TAC film 1: thickness 60 μm, TAC film 2: thickness 40 μm). ∙ Polarizing plate with adhesive layer [II]: TAC film / PVA film (polarizing plate) / COP film (corona treatment) / adhesive layer / release sheet. The above TAC film is triethylfluorenyl Cellulose film (thickness: 50 μm), COP film-based cycloolefin film (thickness: 60 μm). The following evaluations were performed using the polarizing plate [I] with an adhesive layer and the polarizing plate [II] with an adhesive layer.

[Reworkability] The polarizing plate [I] with the adhesive layer obtained above was cut into a width of 25 mm, the release sheet was peeled off, and the adhesive layer was pushed to an alkali-free glass ("EAGLE XG" by Corning Corporation) (Thickness: 1.1 mm), laminated with 2 kg rollers, and subjected to autoclave treatment (0.5 MPa × 50 ° C × 20 minutes), and then left to stand in an environment of 23 ° C × 50% RH for 24 hours, and then measured at a peeling angle of 180 °, peeling speed at 300 mm / min. Peeling force when peeled, and evaluated according to the following criteria. (Evaluation criteria) ◎ ∙∙∙ Under 10N / 25mm ○ ∙∙∙ 10N / 25mm or more and less than 16N / 25mm △ ∙∙∙ 16N / 25mm or more and less than 20N / 25mm × ∙∙ 20N / 25mm or more, Residual glue

[Production of samples for moisture and heat whitening test] The polarizing plate [II] with an adhesive layer was cut into 3.5 cm × 3.5 cm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass ( "EAGLE XG" manufactured by Corning Corporation: thickness: 1.1 mm), after laminating it back and forth twice with a 2 kg roller, autoclave treatment (0.5 MPa x 50 ° C x 20 minutes) was performed to obtain a sample for the moist heat whitening resistance test. Using the obtained test sample, the wet heat whitening resistance of the adhesive layer was evaluated in the following manner.

[Moisture and whitening resistance] After exposing the sample for the moist and heat whitening resistance test to an environment of 60 ° C. × 90% RH for 250 hours, the sample was taken out and left at room temperature (23 ° C.). The haze was measured immediately after taking out and 3 hours after taking out, and the moist heat whitening resistance was evaluated according to the following criteria. The haze value is a value obtained by subtracting a blank 1.1 mm alkali-free glass. (Evaluation criteria) ∙ The haze at the time of taking out is less than 1% ○ ∙∙∙ 1% or more and less than 2% △ ∙∙∙ 2% or more and less than 4% × ∙∙∙ 4% or more ∙ Haze after taking out 3 hours ◎ ∙∙∙ Less than 1% ○ ∙∙∙ 1% or more and less than 2% △ ∙∙∙ 2% or more and less than 4% × ∙∙∙ 4% or more

[Durability] <Damp and heat resistance evaluation> The polarizing plate [I] with an adhesive layer was cut into 20 cm × 15 cm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass (manufactured by Corning Corporation). "EAGLE XG": thickness 1.1 mm), after laminating it back and forth twice with a 2 kg roller, autoclave treatment (0.5 MPa x 50 ° C x 20 minutes) was performed to obtain a sample for the initial durability test. The obtained sample was exposed to an environment of 60 ° C. × 90% RH for 250 hours, and a durability test was performed. After taking out, the durability was evaluated in the following manner. (Evaluation criteria) ○ ∙∙∙ No foaming or end-floating was observed across the polarizing plate × ∙∙∙ Foaming or end-floating was observed across the polarizing plate

<Evaluation of heat resistance> The above polarizing plates [I] and [II] with an adhesive layer were cut into 20 cm × 15 cm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass (manufactured by Corning Corporation) "EAGLE XG": thickness 1.1 mm), after laminating it back and forth twice with a 2 kg roller, autoclave treatment (0.5 MPa x 50 ° C x 20 minutes) was performed to obtain a sample for the initial durability test. The obtained sample was exposed to an environment at 80 ° C for 250 hours and subjected to a durability test. After being taken out, the durability was evaluated in the following manner. (Evaluation criteria) ○ ∙∙∙ No foaming or end-floating was observed across the polarizing plate × ∙∙∙ Foaming or end-floating was observed across the polarizing plate

[Durability after deterioration promotion test (test after exposure to high humidity conditions)] <Damp and heat resistance> The obtained polarizing plate with an adhesive layer [I] was exposed in an environment of 45 ° C. × 90% RH 3 In the future, the temperature and humidity were adjusted for one week in an environment of 23 ° C. × 50% RH to obtain a polarizing plate with an adhesive layer after deterioration promotion. The obtained polarizing plate was cut into 20 cm × 15 cm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass ("EAGLE XG" manufactured by Corning Corporation: thickness 1.1 mm), and pasted twice with a 2 kg roller After the combination, an autoclave treatment was performed (0.5 MPa × 50 ° C. × 20 minutes) to obtain a sample for durability after the degradation promotion test. The obtained sample was exposed to an environment of 60 ° C. × 90% RH for 250 hours and subjected to a durability test. After being taken out, the durability was evaluated in the following manner. (Evaluation criteria) ○ ∙∙∙ No foaming or end-floating was observed across the polarizing plate × ∙∙∙ Foaming or end-floating was observed across the polarizing plate

<Heat resistance> The polarizing plate [I] obtained with an adhesive layer was previously exposed to an environment of 45 ° C × 90% RH for 3 days, and then subjected to temperature adjustment and adjustment for one week in an environment of 23 ° C × 50% RH. Wet and obtain a polarizing plate with an adhesive layer after deterioration promotion. The obtained polarizing plate was cut into 20 cm × 15 cm, the release sheet was peeled off, and the adhesive layer was pressed to an alkali-free glass ("EAGLE XG" manufactured by Corning Corporation: thickness 1.1 mm), and pasted twice with a 2 kg roller After the combination, an autoclave treatment was performed (0.5 MPa × 50 ° C. × 20 minutes) to obtain a sample for durability after the degradation promotion test. The obtained sample was exposed to an environment of 80 ° C for 250 hours and subjected to a durability test. After being taken out, the durability was evaluated in the following manner. (Evaluation criteria) ○ ∙∙∙ No foaming or end-floating was observed across the polarizing plate × ∙∙∙ Foaming or end-floating was observed across the polarizing plate

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

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

【table 3】 *: Unable to evaluate

It can be seen that Examples 1 to 5 using an adhesive containing an acrylic resin having a polar group of 5 to 50% by weight and a silane coupling agent containing an alkoxy group having a carbon number of 2 or more are excellent in moist heat whitening and storage stability .

On the other hand, Comparative Examples 1 and 2 with less polar groups of acrylic resin had poor moist-heat whitening resistance, Comparative Example 3 with more polar groups of acrylic resin but containing a silane coupling agent composed only of methoxy groups. ~ 5, excellent moist heat and whitening resistance, but poor storage stability due to water penetration, and poor durability after the deterioration promotion test.

In addition, using the adhesive obtained by cross-linking the acrylic adhesive composition of Examples 1 to 5 above, a polarizing plate and a liquid crystal cell were bonded to produce an image display device. As a result, the obtained image display device could be manufactured with good accuracy. , And durability is also excellent.

The above-mentioned embodiments are described with respect to specific forms of the present invention, and the above-mentioned embodiments are merely examples and are not to be construed in a limiting sense. Various modifications 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 a polarizing plate in which a polarizing plate is bonded to a glass substrate or the like, excellent durability and moisture-heat whitening resistance can be obtained, and storage stability (after time) Durability), heavy workability, and good balance. Excellent adhesive. Used as an adhesive for displays and optical components used for bonding optical components, especially as a polarizer and a glass substrate for liquid crystal cells. A combined adhesive for polarizing plates is useful.

Claims (11)

An acrylic adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) having at least one reactive functional group and an alkoxy group in the structure, respectively, characterized in that: the acrylic The resin (A) contains 5 to 50% by weight of a structure derived from at least one polar group-containing monomer (a1) selected from a hydroxyl-containing monomer, a carboxyl-containing monomer, and a nitrogen-containing monomer. Unit acrylic resin, at least one of the alkoxy groups contained in the silane coupling agent (B) is an alkoxy group having 2 to 8 carbon atoms. For example, the acrylic adhesive composition according to item 1 of the patent application scope, wherein the polar group-containing monomer (a1) is a hydroxyl group-containing monomer. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope, wherein the alkoxy group having 2 to 8 carbon atoms contained in the silane coupling agent (B) is an ethoxy group. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope, wherein the alkoxy groups contained in the silane coupling agent (B) are ethoxy and methoxy. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope, wherein the silane coupling agent (B) contains 5% or more by weight of an alkoxy group in its structure. For example, the acrylic adhesive composition of claim 1 or 2, wherein the reactive functional group equivalent of the silane coupling agent (B) is 50 to 1000 g / mol. For example, the acrylic adhesive composition according to item 1 or 2 of the patent application scope further contains a crosslinking agent (C). For example, the acrylic adhesive composition of the first or second patent application range further contains an antistatic agent (D). A kind of adhesive, which is obtained by crosslinking the acrylic adhesive composition according to any one of claims 1 to 8 with a crosslinking agent (C). An adhesive for polarizing plates is made by using an adhesive such as item 9 of the patent application scope. An image display device is formed by bonding a polarizing plate and a liquid crystal cell with an adhesive such as the item 9 in the scope of patent application.