KR102358556B1 - Acrylic pressure-sensitive adhesive composition, and pressure-sensitive adhesive made using the same, pressure-sensitive adhesive for polarizing plate, and image display device - Google Patents

Abstract

When used as an adhesive used for bonding between a polarizing plate (protective film) and a liquid crystal cell (glass) in the manufacture of a liquid crystal display device, it exhibits excellent reworkability over a long period of time, is less affected by moisture, and has durability To provide a pressure-sensitive adhesive that does not even occur. In the acrylic pressure-sensitive adhesive composition containing the acrylic resin (A) and the silane coupling agent (B) each containing at least one reactive functional group and at least one alkoxy group in the structure, the silane coupling agent (B) has an alkoxy group content of 15% by weight or less. It is characterized by containing a coupling agent (B1) and a silane coupling agent (B2) whose alkoxy group content is 20 weight% or more.

Description

Acrylic pressure-sensitive adhesive composition, and pressure-sensitive adhesive made using the same, pressure-sensitive adhesive for polarizing plate, and image display device

The present invention relates to an acrylic pressure-sensitive adhesive composition, and a pressure-sensitive adhesive and a pressure-sensitive adhesive for a polarizing plate made using the same, and more particularly, an adhesive that exhibits excellent reworkability over a long period of time, is less affected by moisture and does not reduce durability It relates to an acrylic pressure-sensitive adhesive composition capable of forming

Conventionally, by laminating a polarizing plate on both sides of a polarizer made of a polyvinyl alcohol-based film or the like to which polarization has been imparted with a protective film on the surface of a liquid crystal cell in which an oriented liquid crystal component is sandwiched between two glass plates, an image is displayed The device is being manufactured. In order to laminate|stack a polarizing plate on the surface of this liquid crystal cell, it is common to carry out by making contact with the said liquid crystal cell surface and pressing the adhesive layer provided on the surface of a polarizing plate.

An adhesive containing a polyvinyl alcohol-based resin is very suitably used as an adhesive for bonding the protective film and the polarizer. Specifically, an aqueous solution made by mixing a polyvinyl alcohol-based resin and a crosslinking agent is applied on the polarizer to form a protective film. After lamination|stacking, a polarizing plate is manufactured by heating and drying. In the manufacturing process of the polarizing plate, it is preferable that moisture contained in the adhesive penetrates the protective film, and a triacetyl cellulose film (TAC film) with high moisture permeability has been used very suitably as a protective film, but in recent years, dimensional stability and , an acrylic film, a polyester film, an olefin film, etc. are used instead of the TAC film from the viewpoint of durability. As the olefinic film, in particular, a cycloolefinic film (COP film) is used as a protective film for the polarizer.

The durability of heat resistance and heat-and-moisture resistance is calculated|required by the adhesive used for pasting up of such a polarizing plate and a liquid crystal cell (glass substrate). In particular, in a high-temperature, high-humidity environment, water|moisture content penetrated into an adhesive layer, adhesiveness with a glass substrate fell, and there existed a problem that a polarizing plate floated or peeled off partially from a glass substrate. In order to solve such a problem, improvement in heat-and-moisture resistance has been achieved by blending a silane coupling agent with the pressure-sensitive adhesive. The new problem that a silane coupling agent will deactivate by water|moisture content and durability will fall also arises.

In addition, in the adhesive used for pasting a polarizing plate and a liquid crystal cell (glass substrate), when a polarizing plate is pasted to a liquid crystal cell, when a foreign material is chewed or a position is shifted, the polarizing plate is peeled off to reuse the liquid crystal cell. Reworkability was demanded.

In addition, in recent years, since the yield is improved by the improvement of the precision of the manufacturing process, there is no previous defective product, and the rework process is performed after a certain number of defective products are collected. What can be maintained is calculated|required by an adhesive.

In addition, when a film having a low moisture permeability other than the TAC film, particularly a cycloolefin-based film, is used, when exposed to a moist heat environment, there is a problem that a whitening phenomenon occurs in the pressure-sensitive adhesive layer. This is considered to be caused by the condensation of moisture, which has gradually penetrated into the pressure-sensitive adhesive layer in a moist heat environment, when exposed to room temperature, and the moisture does not escape because it is covered with a film having a low moisture permeability, and the moisture is aggregated to cause whitening.

With respect to such a problem, the adhesive which improved moist-and-heat whitening resistance by using the acrylic resin which copolymerized many polar group containing monomers is proposed.

However, in the pressure-sensitive adhesive using an acrylic resin copolymerized with a large amount of polar group-containing monomers in this way, the adhesiveness with the glass interface increases due to the influence of the polar group, or the pressure-sensitive adhesive layer tends to absorb moisture, so the hydrolysis of the silane coupling agent is accelerated. Furthermore, there existed a problem that rework property and storage stability were inferior.

As an adhesive excellent in such rework property and initial wet-and-heat resistance, for example, in patent document 1, 100 weight part of adhesive resin (A) and an epoxy equivalent are 100-2000 g/mol, and an alkoxyl group content is 5-60 weight. % containing 0.1 to 20 parts by weight of a silicone alkoxy oligomer (B), wherein the pressure-sensitive adhesive resin (A) is an acrylic pressure-sensitive adhesive resin (A1) obtained by polymerizing a monomer that does not contain a carboxyl group, a urethane-based pressure-sensitive adhesive resin (A2), and polyester At least one pressure-sensitive adhesive composition selected from the group consisting of a pressure-sensitive adhesive resin (A3) is described.

Moreover, as an adhesive excellent in moist-heat resistance and whitening property, the adhesive using the acrylic resin with many amounts of hydroxyl groups is proposed by patent document 2, for example.

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

However, in the pressure-sensitive adhesive described in Patent Document 1, both the functional group equivalent and the alkoxy group content are widely stipulated with respect to the silane coupling agent (silicon alkoxy oligomer) used, and it is possible to use various types of silane coupling agents. The adhesive using a silane coupling agent with a large content had a problem that although the adhesive force after initial stage and heating was low, it was inferior to long-term rework property.

Moreover, as demonstrated also in patent document 1, in the adhesive which used the silane coupling agent of a low alkoxy group content for the purpose of improvement of rework property, although it was excellent in rework property, there existed a problem that it was inferior to storage stability.

Moreover, although the adhesive excellent in moist heat and whitening resistance is proposed in the said patent document 2, about long-term rework property and storage stability, neither was considered, but improvement was calculated|required further.

Therefore, in the present invention, under such a background, when used as an adhesive used for bonding between a polarizing plate (protective film) and a liquid crystal cell (glass) at the time of manufacture of an image display device, excellent reworkability is shown over a long period of time , It is also possible to obtain an adhesive that is less affected by moisture and does not deteriorate durability, and also provides an acrylic pressure-sensitive adhesive composition excellent in reworkability and storage stability even when polar groups are increased in consideration of moist heat and whitening resistance. .

However, the present inventors have conducted intensive research in view of such circumstances. As a result, in an acrylic pressure-sensitive adhesive composition containing an acrylic resin and a silane coupling agent, a silane coupling agent with a small alkoxy group content and a silane coupling agent with a large number of silane coupling agents are used in combination for a long period of time. It was discovered that it was possible to obtain an acrylic pressure-sensitive adhesive composition that exhibits excellent reworkability over a period of time, on the other hand, is less affected by moisture and does not cause a decrease in durability.

That is, the present invention relates to an acrylic pressure-sensitive adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and one or more alkoxy groups in the structure, WHEREIN: The alkoxy group content as a silane coupling agent (B) The first summary is an acrylic pressure-sensitive adhesive composition containing a silane coupling agent (B1) of 15 wt% or less and a silane coupling agent (B2) having an alkoxy group content of 20 wt% or more.

In addition, the present invention uses the pressure-sensitive adhesive formed by crosslinking the acrylic pressure-sensitive adhesive composition of the first aspect with a crosslinking agent (C) as the second aspect, and the pressure-sensitive adhesive for a polarizing plate made using the pressure-sensitive adhesive of the second aspect as the third aspect, Moreover, it is to make the image display apparatus which laminated|attached a polarizing plate and a liquid crystal cell together as a 4th summary as an adhesive of 2nd summary.

The present invention relates to an acrylic pressure-sensitive adhesive composition comprising an acrylic resin (A) and a silane coupling agent (B) containing at least one reactive functional group and at least one alkoxy group in the structure, wherein the alkoxy group content as the silane coupling agent (B) is It is an acrylic adhesive composition containing the silane coupling agent (B1) which is 15 weight% or less, and the silane coupling agent (B2) whose alkoxy group content is 20 weight% or more. For this reason, when the adhesive obtained using the acrylic adhesive composition of this invention is used as an adhesive used for bonding of a polarizing plate (protective film) and a liquid crystal cell (glass) at the time of manufacture of an image display device, over a long period of time It is an adhesive which shows excellent rework property, is not affected by moisture, and a decrease in durability does not occur, and is very useful as an adhesive for polarizing plates.

If the acrylic resin (A) is an acrylic resin containing 5 to 50% by weight of a structural unit derived from at least one polar group-containing monomer (a1) selected from a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a nitrogen-containing monomer, then heat-and-moisture whitening resistance and Excellent adhesive properties.

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

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

If the reactive functional group equivalent of the silane coupling agent (B2) is 1,000 g/mol or less, durability is further improved.

When the weight average molecular weight of the said silane coupling agent (B2) is 500 or more, it is further excellent in rework property and durability.

Hereinafter, the present invention will be described in detail.

In the present invention, (meth)acryl means acryl or methacryl, (meth)acryloyl means acryloyl or methacryloyl, and (meth)acrylate means acrylate or methacrylate, respectively. In addition, an acrylic resin is resin obtained by superposing|polymerizing the polymerization component containing at least 1 sort(s) of (meth)acrylate-type monomer.

The acrylic adhesive composition of this 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 preferably contains a structural unit derived from the polar group-containing monomer (a1), and the content thereof is preferably 5 to 50% by weight, for example, containing a polar group. It is preferable that it is an acrylic resin obtained by copolymerizing the copolymerization component containing 5 to 50 weight% of a monomer (a1).

The copolymerization component of the acrylic resin (A) may contain a (meth)acrylic acid alkylester-based monomer (a2) or other copolymerizable ethylenically unsaturated monomers (a3) as needed.

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

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. ) Acrylic acid hydroxyalkyl ester such as acrylate, 8-hydroxyoctyl (meth) acrylate, caprolactone-modified monomer such as caprolactone-modified 2-hydroxyethyl (meth) acrylate, diethylene glycol (meth) acrylate , oxyalkylene-modified monomers such as polyethylene glycol (meth)acrylate, other 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth)acrylamide, hydroxyethyl acrylamide, etc. of primary hydroxyl group-containing monomers; secondary hydroxyl group-containing monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate ; Tertiary hydroxyl group-containing monomers, such as 2, 2- dimethyl 2-hydroxyethyl (meth)acrylate, are mentioned.

Among the hydroxyl group-containing monomers, primary hydroxyl group-containing monomers are preferable, and 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred from the viewpoint of excellent reactivity with a crosslinking agent and improved whitening resistance against moist heat. It is preferable from a viewpoint that there are few impurities, such as (meth)acrylate, and manufacture is easy.

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

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

As said nitrogen-containing monomer, an amino-group containing monomer, an amide group containing monomer, etc. are mentioned, for example.

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

Among the amino group-containing monomers, tertiary amino group-containing monomers are preferable, and dimethylaminoethyl (meth)acrylate is particularly preferable from the viewpoints of storage stability of the resin solution and the crosslinking promoting effect.

As an amide group containing monomer, For example, (meth)acrylamide; Methoxymethyl (meth)acrylamide, ethoxymethyl (meth)acrylamide, propoxymethyl (meth)acrylamide, isopropoxymethyl (meth) Alkoxyalkyl (meth)acrylamide-based monomers such as acrylamide, n-butoxymethyl (meth)acrylamide, and isobutoxymethyl (meth)acrylamide; dimethyl (meth)acrylamide, diethyl (meth)acrylamide, etc. Dialkyl (meth)acrylamide-based monomers; Hydroxyl group-containing amide monomers such as N-(hydroxymethyl)acrylamide; (meth)acryloylmorpholine; and the like.

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

Among the above-mentioned polar group-containing monomers (a1), hydroxyl group-containing monomers and carboxyl group-containing monomers are preferable from the viewpoint of moist heat whitening resistance and adhesion properties, and from the viewpoint of excellent moist heat whitening resistance and long-term reworkability, hydroxyl group-containing monomers is preferable Moreover, the said polar group containing monomer (a1) can be used individually or in combination of 2 or more types.

It is preferable that content of such a polar group containing monomer (a1) (when using 2 or more types together, the total content) is 5-50 weight% with respect to the whole copolymerization component, More preferably, it is 6-30 weight% , more preferably 7 to 25% by weight, particularly preferably 8 to 20% by weight. When such a content is too small, the whitening resistance against moisture and heat tends to decrease when set as an adhesive, and when too large, it tends to be at the time of polymerization It tends to gel.

As the (meth)acrylic acid alkylester-based monomer (a2), for example, the alkyl group has usually 1 to 20 carbon atoms (preferably 1 to 18, particularly preferably 1 to 12, more preferably 1 to 8) , specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate , n-propyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) ) acrylate, cetyl (meth) acrylate, and stearyl (meth) acrylate. These may be used independently and may use 2 or more types together.

Among these, methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferable from a viewpoint of being excellent in versatility and adhesive physical property.

The content of the (meth)acrylic acid alkylester-based monomer (a2) is preferably 20 to 95% by weight, particularly preferably 40 to 94% by weight, more preferably 45 to 93% by weight based on the entire copolymerization component. , in particular 50 to 92% by weight.

When there is too little such content, there exists a tendency for it to become difficult to take the balance of adhesive physical properties, and when too large, there exists a tendency for wet-heat whitening property to fall.

As said other copolymerizable ethylenically unsaturated monomer (a3), for example, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3 -Aromatic ring containing monomers, such as phenoxypropyl (meth)acrylate and orthophenylphenoxyethyl (meth)acrylate; Cyclohexyl (meth)acrylate, cyclohexyloxyalkyl (meth)acrylate, tert- butylcyclohexyl Alicyclic-containing monomers, such as oxyethyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acryl rate, 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene Glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, octoxy polyethylene glycol-polypropylene glycol-mono (meth) Ether chain containing monomers, such as acrylate, lauroxy polyethylene glycol mono(meth)acrylate, and stearic polyethylene glycol mono(meth)acrylate, etc. are mentioned. These may be used independently and may use 2 or more types together.

Among these, from the viewpoint of easy adjustment of the refractive index and birefringence, and from the viewpoint of excellent light wettability, an aromatic ring-containing monomer is preferable (particularly preferably benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol) (meth)acrylate), refractive index and birefringence are easy to adjust, and an alicyclic-containing monomer is preferable from the viewpoint of excellent adhesion to a low-polar adherend (eg, cycloolefin, etc.).

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

As content of the ethylenically unsaturated monomer (a3) which can be copolymerized other than the above, 35 weight% or less is preferable, More preferably, it is 25 weight% or less. When there are too many other copolymerizable ethylenically unsaturated monomers (a3), there exists a tendency for light wettability to fall.

Acrylic resin (A) used in the present invention is a polar group-containing monomer (a1), preferably also (meth) acrylic acid alkyl ester-based monomer (a2) or other copolymerizable ethylenically unsaturated monomer (a3) is appropriately selected, These polymerization components are used, for example, it can manufacture by mixing or dripping such a polymerization component and a polymerization initiator in an organic solvent, and superposing|polymerizing.

The polymerization reaction can be carried out by conventionally known polymerization methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Among them, solution radical polymerization and bulk polymerization are preferred, and solution radical polymerization is particularly preferred. .

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

Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl isobutyl ketone are preferably used from the viewpoint of easiness of polymerization reaction, effect of chain transfer, easiness of drying during adhesive coating, and height of safety. and, more preferably, ethyl acetate, acetone, or methyl ethyl ketone.

These organic solvents may be used independently and may use 2 or more types together.

Moreover, as a polymerization initiator used for such solution radical polymerization, 2, 2'- azobisisobutyronitrile which is a normal radical polymerization initiator, 2, 2'- azobis-2-methylbutyronitrile, for example, is Azo-based initiators such as , 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(methylpropionic acid), benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, Organic peroxides, such as cumene hydroperoxide, etc. are mentioned, According to the monomer to be used, it can select and use it suitably. These polymerization initiators may be used independently and may use 2 or more types together.

The acrylic resin (A) used in the present invention preferably contains 5 to 50% by weight of the structural unit derived from the polar group-containing monomer (a1), particularly preferably 6 to 30% by weight, more preferably 7 -25% by weight, particularly preferably 8-20% by weight and most preferably 8-15% by weight. When there are too few structural units derived from a polar group containing monomer, there exists a tendency for moist-and-heat resistance whitening property to fall easily, and when too large, there exists a tendency for rework property and durability to fall easily.

It is preferable that the weight average molecular weights of the said acrylic resin (A) are 600,000-2.5 million, Especially preferably, it is 800,000-2 million, More preferably, it is 1 million-1.8 million, Especially preferably, it is 1.1 million-1.6 million. .

When such a weight average molecular weight is too small, durability tends to decrease, and when it is too large, a large amount of diluent solvent is required during manufacture, dryness decreases, residual solvent in the pressure-sensitive adhesive layer increases, and heat resistance tends to decrease. .

It is preferable that the dispersion degree (weight average molecular weight/number average molecular weight) of the said acrylic resin (A) is 10 or less, Especially preferably, it is 7 or less, More preferably, it is 5 or less.

When such a dispersion degree is too high, there exists a tendency for rework property to fall or durability to fall. In addition, the lower limit of such a dispersion degree is 1 normally.

In addition, the said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, The high performance liquid chromatograph (The Nippon Waters company make, "Waters 2695 (main body)" and "Waters 2414 (detector)"), column: Shodex GPC KF-806 L (Exclusion limit molecular weight: 2×10 ^7, separation range: 100 to 2×10 ^7, number of theoretical plates: 10,000 steps/piece, filler material: styrene-divinyl benzene copolymer, filler particle size: 10 ㎛) is measured by using three series, and the number average molecular weight can also be measured in the same way. Moreover, dispersion degree is calculated|required from a weight average molecular weight and a number average molecular weight.

It is preferable that the glass transition temperature (Tg) of the said acrylic resin (A) is -80 to 0 degreeC, Especially preferably, it is -60 to -10 degreeC, More preferably, it is -50 to -20 degreeC.

When such a glass transition temperature is too high, there exists a tendency for a tack to fall easily, and when too low, there exists a tendency for heat resistance to fall.

In addition, the said glass transition temperature is calculated by the formula of the following Fox.

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: glass transition temperature (K) of homopolymer of monomer B Wb: weight fraction of monomer B

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

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

That is, the glass transition temperature (Tg) of the acrylic resin (A) is a value calculated by applying the glass transition temperature and weight fraction when each monomer constituting the acrylic resin (A) is a homopolymer to the formula of Fox. to be.

The glass transition temperature when the monomer constituting the acrylic resin (A) is a homopolymer is usually measured by a differential scanning calorimeter (DSC), and is a method based on JIS K 7121-1987 or JIS K 6240. can be measured with

The refractive index of the said acrylic resin (A) is 1.440-1.600 normally, Preferably it is 1.460-1.550, Especially preferably, it is 1.470-1.500. In such a refractive index, it is preferable to reduce the difference in the refractive index of the members to be laminated because the optical loss at the member interface is small.

The said refractive index is the value measured by NaD line and 23 degreeC using the refractive index measuring apparatus ("Abbe refractometer 1T" manufactured by Atago Corporation) of the acrylic resin (A) made into a thin film.

It is preferable that the haze of the said acrylic resin (A) single layer is 1.0 or less, Especially preferably, it is 0.8 or less, More preferably, it is 0.5 or less. When such a haze is too high, there exists a tendency for the image quality of the display using this as an adhesive to fall.

The haze was calculated by measuring the diffuse transmittance and the total light transmittance using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.), and substituting the values of the obtained diffuse transmittance and total light transmittance into the following formula. In addition, this machine is based on JISK7361-1.

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

In this way, the acrylic resin (A) used by this invention is obtained.

<Silane coupling agent (B)>

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

In the present invention, as a silane coupling agent (B) containing at least one reactive functional group and at least one alkoxy group in the structure, the silane coupling agent (B1) having an alkoxy group content of 15 wt% or less, and a silane coupling agent having an alkoxy group content of 20 wt% or more (B2) is contained.

The alkoxy group prescribed|regulated by this invention points out the alkoxy group derived from an alkoxysilane, and the alkoxy group contained in the molecule|numerator other than that is not contained.

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

As said reactive functional group, an epoxy group, a (meth)acryloyl group, a mercapto group, a hydroxyl group, a carboxyl group, an amino group, an amide group, an isocyanate group etc. are mentioned, for example. Among these, an epoxy group and a mercapto group are preferable from a viewpoint of being excellent in durability and rework property.

As said alkoxy group, a methoxy group, an ethoxy group, a propoxy group etc. are mentioned, for example. Among these, it is preferable that it is a C1-C8 alkyl group, Especially preferably, it is a C1-C2 alkyl group, Specifically, they are a methoxy group and an ethoxy group.

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

In the present invention, the greatest feature is that the silane coupling agent (B1) having a small alkoxy group content and the silane coupling agent (B2) having a large alkoxy group content are used together. , it is possible to achieve the object of the present invention that is excellent also in durability and storage stability.

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

When there is too much content of such an alkoxy group, long-term rework property will fall.

It is preferable that the weight average molecular weight of a silane coupling agent (B1) is 3,000 or more, Especially preferably, it is 4,000-30,000, More preferably, it is 4,500-20,000, Especially preferably, it is 7,000-18,000.

When such a weight average molecular weight is too small, there exists a tendency for long-term rework property to fall, and when too large, it tends to bleed-out easily and there exists a tendency for durability to fall.

Further, the reactive functional group equivalent of the silane coupling agent (B1) is preferably 1,600 g/mol or less, particularly preferably 100 to 1,000 g/mol, further preferably 200 to 900 g/mol, particularly preferably 300 to 650 g /mol.

If such a reactive functional group equivalent is in the said range, there exists a tendency which is further excellent in durability.

The alkoxy group content of the silane coupling agent (B2) needs to be 20% by weight or more, preferably 20 to 80% by weight, particularly preferably 25 to 70% by weight, and still more preferably 30 to 60% by weight.

When there is too little content of such an alkoxy group, storage stability will fall.

It is preferable that the weight average molecular weight of a silane coupling agent (B2) is 500 or more, Preferably it is 500-5,000, Especially preferably, it is 500-4,500, More preferably, it is 600-4,000.

When such a weight average molecular weight is too small, there exists a tendency for long-term rework property to fall.

Moreover, it is preferable that the reactive functional group equivalent of a silane coupling agent (B2) is 1,000 g/mol or less, Especially preferably, it is 100-900 g/mol, More preferably, it is 300-800 g/mol.

If such a reactive functional group equivalent is the said range, there exists a tendency for durability to improve.

The weight average molecular weight of the said silane coupling agent (B1) and (B2) is a weight average molecular weight by standard polystyrene molecular weight conversion, and can be measured by the following method. Moreover, a number average molecular weight can also be measured by the same method, and a dispersion degree (weight average molecular weight/number average molecular weight) can be calculated|required from a weight average molecular weight and a number average molecular weight.

Apparatus: Gel Permeation Chromatograph

A detector: Differential refractive index detector RI (RI-8020 type made by Tosoh Corporation, sensitivity 32)

Column: TSK gelguardcolumn H _HR -H (1 pc.) (Tosoh Co., Ltd. φ6 mm×4 cm), TSKgel GM H _HR -N (2 pcs.) (Toso Co., Ltd. φ7.8 mm×30 cm)

Solvent: tetrahydrofuran (THF)

Column temperature: 23 degrees Celsius

Flow rate: 1.0 mL/min

Here, with respect to the weight average molecular weights of the silane coupling agents (B1) and (B2), the long-term reworkability and storage stability is that the weight average molecular weight of the silane coupling agent (B1) is larger than the weight average molecular weight of the silane coupling agent (B2). It is preferable because it tends to have an excellent balance of

The silane coupling agent (B) may be a monomeric organosilicon compound or an oligomeric organosilicon compound (organosiloxane compound) such as a dimer or trimer obtained by polycondensation by hydrolysis of a part of the organosilicon compound. An oligomeric organosilicon compound is preferable from the viewpoint of having a plurality of reactive functional groups and alkoxy groups and excellent in durability and reworkability.

As the silane coupling agent (B), for example, an organosilicon compound such as γ-glycidoxypropyltriethoxysilane or γ-glycidoxypropylmethyldiethoxysilane, or a part of the organosilicon compound is hydrolyzed. Epoxy group-containing silane coupling agents such as polycondensed oligomeric organosilicon compounds (eg, epoxy group-containing silicone alkoxy oligomers) or organosilicon compounds obtained by ether modification of some of these organosilicon compounds; organic compounds such as γ-mercaptopropyltriethoxysilane A mercapto group-containing silane coupling agent of an oligomeric organosilicon compound (such as a mercapto group-containing silicone alkoxy oligomer) obtained by hydrolysis and polycondensation of a silicon compound or an organosilicon compound;

Among these, the silane coupling agents (B1) and (B2) can be appropriately selected and used so as to satisfy the respective conditions. Moreover, as for the said silane coupling agent (B1) and (B2), only 1 type may be used, respectively, and may use 2 or more types together.

Specifically as the silane coupling agent (B1), "X-24-9590" (weight average molecular weight: 13,700, contained alkoxy group: methoxy group, alkoxy group content: 9.5 weight%, Reactive functional group: an epoxy group, epoxy equivalent: 592 g/mol) etc. are mentioned.

Specifically as the silane coupling agent (B2), "X-41-1059A" (weight average molecular weight: 2,300, contained alkoxy group: methoxy group, ethoxy group, alkoxy group content: 42 weight% , reactive functional group: epoxy group, epoxy equivalent: 350 g/mol), "X-41-1810" (weight average molecular weight: 640, containing alkoxy group: methoxy group, alkoxy group content: 30 wt%, reactive functional group: mercapto group, Mercapto equivalent: 450 g/mol), "X-41-1805" (weight average molecular weight: 3,450, contained alkoxy group: methoxy group, ethoxy group, alkoxy group content: 50 wt %, reactive functional group: mercapto group, mercapto group equivalent: 800 g/mol) and the like.

Among these, "X-41-1059A" is especially preferable from a viewpoint of storage stability and durability.

It is preferable that content of a silane coupling agent (B1) is 0.001-1 weight part with respect to 100 weight part of acrylic resin (A), Especially preferably, 0.015-0.5 weight part, More preferably, it is 0.020-0.2 weight part, More preferably, it is 0.025-0.15.

When there is too much such content, there exists a tendency for durability to fall, and when too little, there exists a tendency for long-term rework property to fall.

The content of the silane coupling agent (B2) is preferably 0.001 to 1 part by weight with respect to 100 parts by weight of the acrylic resin (A), particularly preferably 0.015 to 0.5 part by weight, further preferably 0.02 to 0.2 part by weight, particularly Preferably it is 0.025-0.15.

When there is too much such content, there exists a tendency for durability to fall, and when too little, there exists a tendency for rework property to fall.

Moreover, it is preferable that the content ratio (weight ratio) of a silane coupling agent (B1) and (B2) is (B1):(B2)=50:1-1:5, Especially preferably, (B1):(B2) is especially preferable. =30:1 to 1:2, more preferably (B1):(B2)=10:1 to 1:1.

When such a content rate is the said range, there exists a tendency excellent in the balance of durability and rework property.

In addition, in the acrylic pressure-sensitive adhesive composition of the present invention, silane coupling agents other than the silane coupling agents (B1) and (B2) can be used in the range that does not impair the effects of the invention, but if the content of the silane coupling agent is too large There is a tendency for durability to decrease due to bleed. For this reason, specifically, it is preferable that content of silane coupling agents other than the said silane coupling agent (B1) and (B2) is 0.5 weight part or less with respect to 100 weight part of acrylic resin (A), More preferably, 0.3 weight part part or less, particularly preferably 0.1 part by weight or less.

It is preferable to contain a crosslinking agent (C) and an antistatic agent (D) other than the said acrylic resin (A) and a silane coupling agent (B) in the acrylic adhesive composition of this invention.

<Crosslinking agent (C)>

Examples of the crosslinking agent (C) include an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, a melamine crosslinking agent, an aldehyde crosslinking agent, an amine crosslinking agent, and a metal chelate crosslinking agent. It is preferable to use an isocyanate-based crosslinking agent from the viewpoint of improving the stability or excellent reactivity with the base polymer.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate crosslinking agents such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, xylene diisocyanate crosslinking agents such as 1,3-xylene diisocyanate, diphenyl Aromatic isocyanate type crosslinking agents, such as diphenylmethane type crosslinking agents, such as methane-4, 4- diisocyanate, naphthalene diisocyanate type crosslinking agents, such as 1,5-naphthalene diisocyanate; Isophorone diisocyanate, 1,4-cyclohexanedi Isocyanate, 4,4'-dicyclohexyl methane diisocyanate, methylcyclohexane diisocyanate, isopropyridenedicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanate methylcyclohexane, norbornandi Alicyclic isocyanate-based crosslinking agent such as isocyanate; Aliphatic isocyanate-based crosslinking agent such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; And adact, biuret, and isocyanurate of the isocyanate compound .

Among these isocyanate-based crosslinking agents, tolylene diisocyanate-based crosslinking agents are preferable from the viewpoint of pot life and durability, and xylene diisocyanate-based crosslinking agents or isocyanurate skeleton-containing isocyanate-based crosslinking agents are preferable from the viewpoint of shortening the aging time. A non-aromatic-free isocyanate-based crosslinking agent is preferable from the viewpoint of yellowing resistance. Among them, specifically, tolylene diisocyanate, xylene diisocyanate, hexamethylene diisocyanate and trimethylolpropane adact form, and isocyanurate form are preferred from the viewpoint of excellent balance of durability, pot life, and crosslinking rate.

As said epoxy-type crosslinking agent, For example, a bisphenol A/epicrolhydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethyleneglycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether , 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl Ether etc. are mentioned.

Examples of the aziridine crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N′-diphenylmethane- 4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), etc. are mentioned.

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, and the like. can be heard

Examples of the aldehyde-based crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutaldialdehyde, formaldehyde, acetaldehyde, and benzaldehyde.

Examples of the amine-based crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, and polyamide. .

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

The said crosslinking agent (C) may be used independently and may use 2 or more types together.

It is preferable that content of the said crosslinking agent (C) is 0.01-5 weight part with respect to 100 weight part of acrylic resin (A), Especially preferably, it is 0.05-1.5 weight part, More preferably, it is 0.1-0.5 weight part.

When there is too little such content, there exists a tendency for durability to fall, and when too large, there exists a tendency for stress relaxation property to fall, for a board|substrate to bend easily, or to require aging for a long time.

<Antistatic agent (D)>

It is preferable to further contain an antistatic agent (D) in the acrylic adhesive composition of this invention, and an ionic compound (D1) is especially suitable as an antistatic agent (D).

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

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

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

Among these, an organic salt is preferable from a viewpoint excellent in corrosion prevention, a viewpoint excellent in long-term rework property, and storage stability, More preferably, an ammonium cation, an imidazolium cation, a pyridinium salt cation, a piperidinium An onium salt composed of a nitrogen-containing cation such as a cation or a pyrrolidinium cation is preferable, particularly preferably an ammonium salt, more preferably an acyclic ammonium cation and an N,N-bis(trifluoromethanesulfonyl)imide anion , an ammonium salt consisting of an acyclic ammonium cation and an N,N-bis(fluorosulfonyl)imide anion.

It is preferable that melting|fusing point of the ionic compound (D1) is 10-100 degreeC, Especially preferably, it is 20-80 degreeC, Especially preferably, it is 25-50 degreeC. When such melting point is too high, there exists a tendency for it to precipitate easily at low temperature, and when too low, there exists a tendency for discoloration of a polarizing plate to easily generate|occur|produce in a moist heat environment.

It is preferable that content of antistatic agent (D) is 0.5-10 weight part with respect to 100 weight part of acrylic resin (A), More preferably, it is 2-8 weight part, More preferably, it is 2-5 weight part, Especially preferably. Usually 2.5 to 4.5 parts by weight. When the content is too small, antistatic performance cannot be obtained and display unevenness tends to occur due to static electricity.

In addition, in the acrylic pressure-sensitive adhesive composition of the present invention, resin components, acrylic monomers, polymerization inhibitors, antioxidants, corrosion inhibitors, crosslinking accelerators, radical generators, peroxides, radical trapping as other components in the range not impairing the effects of the present invention Various additives, such as an agent, a metal, resin particle, etc. can be mix|blended. In addition, in addition to the above, it may contain a small amount of impurities, etc. included in the raw materials for manufacturing the constituent components of the acrylic pressure-sensitive adhesive composition.

It is preferable that content of the said other component is 5 weight part or less with respect to 100 weight part of acrylic resin (A), Especially preferably, it is 1 weight part or less, More preferably, it is 0.5 weight part or less. When there is too much such content, compatibility with acrylic resin (A) will fall and there exists a tendency for moist-heat resistance whitening property to fall.

In this way, by mixing an acrylic resin (A), a silane coupling agent (B), a crosslinking agent (C), an antistatic agent (D), and other components as needed, the acrylic adhesive composition of this invention can be obtained. In addition, the mixing method is not particularly limited, and various methods, such as a method of mixing each component at once, a method of mixing arbitrary components, and a method of mixing the remaining components at once or sequentially, may be employed. can

The acrylic pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by curing (crosslinking), and by laminating and forming a pressure-sensitive adhesive layer made of such a pressure-sensitive adhesive on an optical member (optical laminate), an optical member with a pressure-sensitive adhesive layer can be obtained have.

In the said optical member with an adhesive layer, it is preferable to provide a release sheet again in the surface opposite to the optical member surface of an adhesive layer.

As a manufacturing method of the said optical member with an adhesive layer,

[1] A method of applying and drying an acrylic pressure-sensitive adhesive composition on an optical member, bonding a release sheet, and performing a treatment by aging at at least one of room temperature (23° C.) or a heated state;

[2] A method of applying and drying an acrylic pressure-sensitive adhesive composition on a release sheet, bonding an optical member, and performing a treatment by aging in at least one of room temperature or a heated state; and the like.

Among these, the method of aging at room temperature by the method [2] is preferable from a viewpoint of not damaging an optical member, and a viewpoint of being excellent in adhesiveness with an optical member.

Moreover, in the case of a polarizing plate, it is especially effective as an optical member in the above.

Such an aging treatment is performed to balance the physical properties of the adhesive as a reaction time for chemical crosslinking of the pressure-sensitive adhesive, and as conditions for aging, the temperature is usually room temperature to 70° C., and the time is usually 1 to 30 days, specifically, For example, it can also carry out under conditions, such as 1 to 20 days at 23 degreeC, 3 to 10 days at 23 degreeC, and 1 to 7 days at 40 degreeC.

When applying the acrylic pressure-sensitive adhesive composition, it is preferable to dilute the acrylic pressure-sensitive adhesive composition in a solvent and apply, and the dilution concentration is preferably 5 to 60% by weight as solid content concentration, particularly preferably 10 to 30% by weight.

The solvent is not particularly limited as long as it dissolves the acrylic pressure-sensitive adhesive composition, and for example, ester solvents such as methyl acetate, ethyl acetate, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, and methyl isobutyl Ketone solvents, such as ketone, aromatic solvents, such as toluene and xylene, alcohol solvents, such as methanol, ethanol, and propyl alcohol, can be used. Among these, ethyl acetate and methyl ethyl ketone are suitably used from a viewpoint of solubility, dryness, price, etc.

Moreover, about application|coating of the said adhesive composition, it can implement by conventional methods, such as roll coating, die coating, gravure coating, comma coating, and screen printing.

About the gel fraction of the adhesive layer manufactured by the said method, it is preferable that it is 30 to 95 weight% from a viewpoint of durability performance and polarization degree fall suppression, Especially preferably, it is 40 to 90 weight%, More preferably, it is 60 -85% by weight. When the gel fraction is too low, the reworkability tends to decrease, and when the gel fraction is too high, floatation or peeling tends to occur.

The gel fraction serves as a criterion for the degree of crosslinking (degree of curing), and is, for example, calculated by the following method. That is, the pressure-sensitive adhesive layer is formed on the base material such as an optical member, particularly a polarizing plate, and the pressure-sensitive adhesive is collected from the pressure-sensitive adhesive sheet by picking, the pressure-sensitive adhesive is wrapped with a 200-mesh SUS wire mesh, and immersed in ethyl acetate adjusted to 23°C for 24 hours. and the weight percentage of the insoluble pressure-sensitive adhesive component remaining in the wire mesh as the gel fraction.

In addition, when adjusting the gel fraction of an adhesive to the said range, it is achieved by adjusting the kind and quantity of a crosslinking agent, etc.

The pressure-sensitive adhesive layer produced by the above method is preferable because it tends to improve the workability because it has good wettability when actually sticking to an adherend that has a good tack feeling as when it is touched with a finger.

As electrical properties of the pressure-sensitive adhesive layer obtained by using the acrylic resin composition of the present invention, the surface resistance value is preferably 1×10 ¹² Ω or less, particularly preferably 1×10 ¹¹ Ω or less, more preferably 5×10 ¹⁰ Ω or less. When such a surface resistance value is too high, a polarizing plate and an adhesive layer become easy to charge, and there exists a tendency for display unevenness to occur easily.

Moreover, 5-200 micrometers is preferable, especially 10-100 micrometers is preferable, and, as for the thickness of the adhesive layer after drying in the optical member with an adhesive layer obtained, 10-30 micrometers is preferable. When the thickness of the pressure-sensitive adhesive layer is too thin, the adhesive properties tend to be difficult to be stabilized, and when the pressure-sensitive adhesive layer is too thick, the amount of moisture ingress from the end portion tends to increase and storage stability tends to decrease.

In the present invention, the optical member with a pressure-sensitive adhesive layer, particularly a polarizing plate with an pressure-sensitive adhesive layer, is directly or has a release sheet, after peeling the release sheet, the pressure-sensitive adhesive layer surface is bonded to a glass substrate, and is provided, for example, to an image display device.

The initial adhesive force of the pressure-sensitive adhesive of the present invention is appropriately determined depending on the material of the adherend and the like. For example, when bonding to glass substrates, such as a liquid crystal cell, it is preferable to have adhesive force of 15 N/25 mm or less, Especially preferably, it is 0.1-12 N/25 mm, More preferably, it is 0.5-8 N/25 mm.

The long-term adhesive force (rework property) of the pressure-sensitive adhesive of the present invention is appropriately determined depending on the material of the adherend and the like. For example, when bonding to glass substrates, such as a liquid crystal cell, it is preferable that the adhesive force after pasting 40 days is 0.1-20 N/25 mm, Especially preferably, 1-15 N/25 mm, More preferably, 1- It is 10N/25mm.

The initial adhesive force is calculated as follows.

With respect to the polarizing plate with an adhesive layer, cut to a width of 25 mm, peel the release film, press the adhesive layer side to an alkali-free glass plate (made by Corning, "Eagle XG"), and bond the polarizing plate and the glass plate. After that, autoclave treatment (50° C. × 0.5 MPa × 20 minutes) was performed, and after standing at 23° C. × 50% RH for 24 hours, peeling test was performed at a peeling angle of 180° and a peeling rate of 300 mm/min. do. Moreover, regarding long-term rework property, after leaving it to stand for a predetermined period at 23 degreeC x 50%RH after an autoclave process, peeling test is implemented by 180 degree peeling angle and 300 mm/min of peeling speed|rate.

The acrylic pressure-sensitive adhesive composition of the present invention is excellent in durability and heat-and-moisture whitening resistance, and at the same time, it is possible to obtain an adhesive excellent in storage stability and reworkability in a well-balanced manner. It is useful as an adhesive for polarizing plates.

Examples of the protective film constituting the polarizing plate include a triacetyl cellulose-based film, an acrylic film, a polyethylene-based film, a polypropylene-based film, and a cycloolefin-based film. Although used, it is especially preferable from a viewpoint that the effect of this invention is easy to acquire the polarizing plate on which the cycloolefin film was laminated|stacked.

Moreover, by using the said adhesive, an image display apparatus can be produced by bonding a polarizing plate and a liquid crystal cell, and the image display apparatus obtained can be produced with precision, and it becomes excellent in durability.

(Example)

Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the following Example unless the summary is exceeded. In addition, in the Example, "part" and "%" mean a weight basis.

First, various acrylic resins were prepared as follows. In addition, about the acrylic resin (A), a weight average molecular weight, a dispersion degree, and a glass transition temperature, it measured according to the method mentioned above.

In addition, regarding the measurement of a viscosity, it measured according to the 4.5.3 rotational viscometer method of JISK5400 (1990).

<Acrylic resin (A)>

[Production of acrylic resin (A-1)]

Into a four-bottomed round-bottomed flask equipped with a reflux condenser, stirrer, nitrogen gas inlet and thermometer, 8 parts of 2-hydroxyethyl acrylate (a1), 0.7 parts of acrylic acid (a1), and n-butyl acrylate (a2) 71.3 parts, benzyl acrylate (a3) 20 parts, ethyl acetate 53 parts, acetone 42 parts, and azobisisobutyronitrile (AIBN) 0.013 parts as a polymerization initiator were added, and the internal temperature was raised to the boiling point to initiate the reaction. . Next, 30 parts of an ethyl acetate solution containing 0.04% of AIBN is added dropwise, reacted at reflux temperature for 3.25 hours, diluted with ethyl acetate, and an acrylic resin (A-1) solution (solid content 21.3%, viscosity 5440 mPa·s/25°C) , Acrylic resin (A-1): Glass transition temperature -42 degreeC, weight average molecular weight 1.27 million, dispersion degree 4.3) were obtained.

As the monomers used above, those made by the following manufacturers were used.

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

・Acrylic acid (manufactured by Mitsubishi Chemical Co., Ltd. Tg 106°C)

-Butyl acrylate (Mitsubishi Chemical Co., Ltd. Tg -56 degreeC)

・Benzyl acrylate (Viscoat #160Tg 6°C, manufactured by Osaka Yugi Chemical Co., Ltd.)

In addition, the said Tg is Tg of the homopolymer of each monomer.

[Production of acrylic resins (A-2) and (A-3)]

It carried out according to the manufacturing method of the said acrylic resin (A-1) using the copolymerization component of Table 1, and obtained the acrylic resin (A-2) and (A-3) solution. In addition, the obtained acrylic resin (A-2) and (A-3) solutions are as having described in Table 1.

<Silane coupling agent (B)>

The following were prepared as a silane coupling agent (B). About the weight average molecular weight and dispersion degree of a silane coupling agent (B), it measured according to the method mentioned above. In addition, catalog values were employ|adopted about alkoxy group content, reactive functional group, epoxy equivalent or mercapto equivalent, and containing alkoxy group.

-(B1-1): (Shin-Etsu Chemical Co., Ltd. make, "X-24-9590", weight average molecular weight: 13,700, dispersion degree: 3.44, alkoxy group content: 9.5%, reactive functional group: epoxy group, epoxy equivalent: 592 g /mol, containing alkoxy group: methoxy group)

-(B2-1): (Shin-Etsu Chemical Co., Ltd. make, "X-41-1059 A", weight average molecular weight: 2,270, dispersion degree: 1.86, alkoxy group content: 42%, reactive functional group: epoxy group, epoxy equivalent: 350 g/mol, containing alkoxy groups: methoxy group, ethoxy group)

・(B2-2)

(Shin-Etsu Chemical Co., Ltd., "X-41-1805", weight average molecular weight: 3, 450, dispersion degree: 1.85, alkoxy group content: 50%, reactive functional group: mercapto group, mercapto equivalent: 800 g/mol , containing alkoxy group: methoxy group, ethoxy group),

<Crosslinking agent (C)>

The following were prepared as a crosslinking agent (C).

(C-1): Adact form of tolylene diisocyanate and trimethylol propane (Tosoh Corporation make, "Colonate L55E": active ingredient 55%)

<Antistatic agent (D)>

As the antistatic agent (D), the following were prepared.

(D1-1): tri-n-butylmethylammonium N,N-bis(trifluoromethanesulfonyl)imide (manufactured by 3M, "FC-4400")

<Examples 1-4, Comparative Examples 1-5>

The above components (A) to (D) were blended as shown in Table 2 below, and the solid content concentration was adjusted to 12.5% in ethyl acetate to obtain an acrylic pressure-sensitive adhesive composition.

Using the acrylic pressure-sensitive adhesive composition obtained above, a sample for evaluation was prepared as follows, and the following performance was evaluated. Table 3 shows the evaluation results.

[Preparation of polarizing plates [I] and [II] with an adhesive layer]

The obtained acrylic pressure-sensitive adhesive composition was applied to a release sheet having a thickness of 38 μm (“Lumira SP-0138BU” manufactured by Mitsui Chemicals Higashi Cell Co., Ltd.) so that the thickness after drying was 25 μm, dried at 100° C. for 3 minutes, and then triacetyl cellulose ( TAC) On the surface of the TAC film on one side of the polarizing plate in which the film was laminated on both sides, the release sheet and the opposite side of the pressure-sensitive adhesive layer were pasted together and aged for 7 days in an environment of 23 ° C. × 50% RH, to obtain a polarizing plate [I] with an adhesive layer ( Layer composition: release sheet/adhesive layer/TAC film 1/polarizer/TAC film 2, TAC film 1: thickness 40 µm, TAC film 2: 60 µm).

Moreover, it carried out similarly except having pasted the COP surface of the cycloolefin type film/polarizer/TAC type film to which corona-treated, and the adhesive layer surface, and obtained the polarizing plate [II] with an adhesive layer.

In addition, the TAC film is a triacetyl cellulose film (thickness 60㎛), the COP film is a cycloolefin film (50㎛ thickness).

The following evaluation was performed using the said polarizing plate [I] with an adhesive layer and polarizing plate [II] with an adhesive layer.

[rework property]

The polarizing plate [I] with a pressure-sensitive adhesive layer obtained above was cut to a width of 25 mm, the release sheet was peeled off, the pressure-sensitive adhesive layer surface was pressed against alkali-free glass ("Eagle XG" manufactured by Corning Corporation: 1.1 mm thick), and adhered with a 2 kg roller, followed by autoclaving (0.5 MPa×50° C.×20 minutes), then left still for 1 day, 40 days, and 50 days in an environment of 23° C.×50% RH, and thereafter, a peeling angle of 180° and 300 mm/min. The adhesive force at the time of peeling off at a peeling speed was measured, and the following reference|standard evaluated.

(Evaluation standard)

・1 day after bonding

◎···5N/25mm or less

○···Higher than 5N/25mm and less than 10N/25mm

×···10N/25mm or more

・After 40 days

◎···10N/25mm or less

○···Higher than 10N/25mm and less than 15N/25mm

△...15N/25mm or more, less than 2N/25mm

×···20N/25mm or more, or residual glue occurs

・After 50 days

◎···10N/25mm or less

○···Higher than 10N/25mm and less than 18N/25mm

△...18N/25mm or more, less than 20N/25mm

×···20N/25mm or more, or residual glue occurs

〔durability〕

<Evaluation of initial durability>

The obtained polarizing plate [I] with an adhesive layer was cut to 20 cm x 15 cm, the release sheet was peeled off, the adhesive layer surface was pressed against alkali-free glass ("Eagle XG" manufactured by Corning Corporation: thickness 1.1 mm), and the 2 kg roller was used to reciprocate and stick together. , an autoclave treatment (0.5 MPa × 50°C × 20 minutes) was performed to prepare a sample for an initial durability test.

About the obtained sample, the following evaluation was performed about the polarizing plate after exposing to the conditions of (1) heat resistance (80 degreeC x 250 hours), (2) heat-and-moisture resistance (60 degreeC x 90%RH x 250 hours).

(Evaluation standard)

○··· No foaming on the front of the polarizing plate or floating at the end

×... Foaming on the front of the polarizing plate or floating at the end

<Evaluation after deterioration acceleration test>

After exposing the obtained polarizing plate [I] with an adhesive layer in the environment of 45 degreeC and 90 %RH for 3 days, it temperature-controlled and humidity control in 23 degreeC and 50 %RH environment for 7 days. After that, it was cut to 20 cm × 15 cm, the release sheet was peeled off, the pressure-sensitive adhesive layer surface was pressed against alkali-free glass (“Eagle XG” manufactured by Corning Corporation: 1.1 mm thick) and adhered in two reciprocations with a 2 kg roller, followed by autoclave treatment (0.5 MPa) x 50 degreeC x 20 minutes), and the sample for deterioration acceleration|stimulation test was produced.

About the obtained sample, the following evaluation was performed about the polarizing plate after exposing on the conditions of (1) heat resistance (80 degreeC x 250 hours), and (2) heat-and-moisture resistance (60 degreeC x 90%RH x 250 hours).

(Evaluation standard)

○··· Foaming or floating cannot be seen on the entire surface of the polarizing plate.

×··· Foaming or floating can be seen on the entire surface of the polarizing plate.

[moisture and heat whitening resistance]

The obtained polarizing plate [II] with an adhesive layer was cut to 3.5 cm x 3.5 cm, the release sheet was peeled off, the adhesive layer surface was pressed against alkali-free glass ("Eagle XG" manufactured by Corning: 1.1 mm thick), followed by 2 reciprocating bonding with a 2 kg roller. After printing, the autoclave process (0.5 MPa x 50 degreeC x 20 minutes) was implemented and the sample for moist-and-heat resistance whitening test was produced.

About the obtained sample, after exposing for 250 hours in the environment of 60 degreeC x 90 %RH, it extracted and left to stand at room temperature. And after taking out, the haze 3 hours after was measured, and the following reference|standard evaluated moist-and-heat whitening resistance. In addition, a haze value is the value which subtracted the value of 1.1 mm alkali free glass as a blank.

(Evaluation standard)

・Haze 3 hours after taking it out

◎...less than 1%

○··· 1% or more, less than 2%

△···2% or more, less than 4%

×···4% or more

[Gel fraction]

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

[Antistatic properties]

<Surface resistance value>

After the polarizing plate [I] with an adhesive layer was left still for 24 hours in an atmosphere of 23°C x 50%RH, the release sheet of the adhesive layer was removed and a surface resistivity measuring device (manufactured by Mitsubishi Chemical Anaritech Co., Ltd., device name “Hiresta-” UPMCP-HT450') was used to measure the surface resistivity of the pressure-sensitive adhesive layer.

From the above results, in Examples 1 to 4 using the adhesive obtained as an acrylic pressure-sensitive adhesive composition in which a silane coupling agent (B1) having an alkoxy group content of 15 wt% or less and a silane coupling agent (B2) having an alkoxy group content of 20 wt% or more was used in combination. It can be seen that long-term reworkability, storage stability, and durability are well balanced.

In addition, in Comparative Examples 1 and 2, in which the silane coupling agent (B2) having an alkoxy group content of 20 wt% or more was not used and only the silane coupling agent (B1) having an alkoxy group content of 15 wt% or less was used, long-term reworkability was not excellent. However, it turns out that it is inferior to storage stability. Further, in Comparative Examples 3 to 5 in which the silane coupling agent (B1) having an alkoxy group content of 15 wt% or less was not used and only the silane coupling agent (B2) having an alkoxy group content of 20 wt% or more was used, the long-term reworkability was poor. it can be seen that

In addition, an image display device was manufactured by bonding a polarizing plate and a liquid crystal cell using an adhesive in which the acrylic pressure-sensitive adhesive composition of Examples 1 to 4 was crosslinked.

Although the said Example showed about the specific form in this invention, the said Example is only a mere illustration, and is not interpreted limitedly. Various modifications apparent to those skilled in the art are expected to be within the scope of the present invention.

The acrylic pressure-sensitive adhesive composition of the present invention exhibits excellent reworkability over a long period of time when used as an adhesive used for bonding between a polarizing plate (protective film) and a liquid crystal cell (glass) in the production of a liquid crystal display device, and , it is possible to obtain a pressure-sensitive adhesive that is less affected by moisture and does not cause a decrease in durability, and an adhesive for an optical member for bonding a display or an optical component constituting it, in particular, for bonding a polarizing plate and a glass substrate of a liquid crystal cell, etc. It is useful as an adhesive for polarizing plates.

Claims (11)

In the acrylic pressure-sensitive adhesive composition containing the acrylic resin (A) and the silane coupling agent (B) each containing at least one reactive functional group and one or more alkoxy groups in the structure,
The silane coupling agent (B) contains a silane coupling agent (B1) having an alkoxy group content of 1 to 15 wt%, and a silane coupling agent (B2) having an alkoxy group content of 20 to 80 wt%,
The acrylic pressure-sensitive adhesive composition, characterized in that the weight average molecular weight of the silane coupling agent (B2) is 500 or more. The method according to claim 1,
The acrylic resin (A) is an acrylic resin containing 5 to 50% by weight 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. adhesive composition. The method according to claim 1 or 2,
The acrylic pressure-sensitive adhesive composition, characterized in that the reactive functional group equivalent of the silane coupling agent (B1) is 1,600 g/mol or less. The method according to claim 1 or 2,
The acrylic pressure-sensitive adhesive composition, characterized in that the weight average molecular weight of the silane coupling agent (B1) is 3,000 or more. The method according to claim 1 or 2,
The acrylic pressure-sensitive adhesive composition, characterized in that the reactive functional group equivalent of the silane coupling agent (B2) is 1,000 g/mol or less. delete The method according to claim 1 or 2,
An acrylic pressure-sensitive adhesive composition further comprising a crosslinking agent (C). The method according to claim 1 or 2,
An acrylic pressure-sensitive adhesive composition further comprising an antistatic agent (D). A pressure-sensitive adhesive, characterized in that the acrylic pressure-sensitive adhesive composition according to claim 1 or 2 is crosslinked by a crosslinking agent (C). A pressure-sensitive adhesive for a polarizing plate, characterized in that it is made using the pressure-sensitive adhesive according to claim 9. The pressure-sensitive adhesive according to claim 9, wherein a polarizing plate and a liquid crystal cell are pasted together to form an image display device.