JP2004190012A - Acrylic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an acrylic resin composition which can abbreviate the stress concentration of an optical film caused by its extension and contraction, or the like, can suppress the void and color unevenness of an optical laminate, can suppress the delamination between a glass base and a pressure-sensitive adhesive layer in an optical laminate, can suppress foaming in the pressure-sensitive adhesive layer and is suitable for a pressure-sensitive adhesive. <P>SOLUTION: This acrylic resin composition comprises (1) an acrylic resin which comprises (a) a structural unit derived from (a) a (meth)acrylate and (b) a structural unit derived from (b) a monomer having at least two olefinic double bonds in its molecule, and (2) a straight chain acrylic resin whose main component is the structural unit (a). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an acrylic resin composition, a pressure-sensitive adhesive comprising the resin composition, and an optical laminate including the pressure-sensitive adhesive.

A liquid crystal cell has a structure in which a liquid crystal component is sandwiched between two glass substrates. On the surface of the glass substrate, a polarizing film, a retardation film, or the like is provided via an adhesive mainly composed of an acrylic resin. To give an optical laminate used for a liquid crystal display device such as a TFT or STN.
As a method for producing an optical laminate, a method in which an adhesive is first laminated on an optical film to obtain an optical film with an adhesive, and then a glass substrate is laminated on the surface of the adhesive is generally used.

  Such an optical film with a pressure-sensitive adhesive is liable to curl due to a large dimensional change due to expansion and contraction under heat or wet heat conditions, and foams in the pressure-sensitive adhesive layer of the obtained optical laminate, or the pressure-sensitive adhesive layer and the glass substrate There is a problem that separation between the two occurs. Furthermore, under heat or wet heat conditions, the distribution of residual stress acting on the pressure-sensitive adhesive optical film becomes non-uniform, and stress concentration occurs on the outer peripheral portion of the optical laminate, resulting in display unevenness such as white spots and color unevenness. There was a problem.

  In order to solve such a problem, it has been proposed to use, as an adhesive, a resin composition comprising an acrylic resin having a weight average molecular weight of 600,000 to 2,000,000 in terms of polystyrene and an acrylic resin having the same weight average molecular weight of 500,000 or less. Specifically, a pressure-sensitive adhesive containing an acrylic resin composition of butyl acrylate / acrylic acid copolymer (the same weight average molecular weight of 1,500,000) and butyl acrylate / hydroxyethyl acrylate copolymer (the same weight average molecular weight of 100,000) Its use is disclosed (Patent Document 1).

JP-A-2000-109771 ([Claims] and Example 1)

The present inventor has studied the above-mentioned pressure-sensitive adhesive, and has found that it may not be possible to sufficiently suppress the separation between the pressure-sensitive adhesive layer and the glass substrate in the optical laminate.
An object of the present invention is to alleviate stress concentration caused by expansion and contraction of an optical film, to suppress white spots and color unevenness of an optical laminate, and to prevent the optical laminate and an adhesive layer from floating and peeling off in the optical laminate. An acrylic resin composition suitable for an adhesive capable of suppressing foaming in an adhesive layer; an adhesive containing the acrylic resin; an optical film with an adhesive comprising the adhesive and an optical film; and the adhesive An object of the present invention is to provide an optical laminate in which an optical film and a glass substrate are laminated via a pressure-sensitive adhesive layer of an attached optical film.

  The present inventors have conducted intensive studies to solve such problems, and found that a specific acrylic resin composition was suitable as an adhesive, and an optical laminate for re-attaching an optical film with an adhesive. It was found that even after the film was peeled off, the surface of the glass substrate in contact with the pressure-sensitive adhesive layer hardly fogged or remained glue, that is, it was excellent in reworkability, and completed the present invention.

  That is, the present invention provides an acrylic resin composition containing the following acrylic resins (1) and (2); an adhesive obtained by blending the acrylic resin composition with a curing agent and / or a silane compound; An optical film with an adhesive comprising an agent and an optical film; an optical laminate comprising the optical film with an adhesive and a glass substrate.

Acrylic resin (1): an acrylic resin containing a structural unit derived from the following (a) (structural unit (a)) and a structural unit derived from the following (b) (structural unit (b)).

Acrylic resin (2): A linear acrylic resin containing the structural unit (a) as a main component.

（式中、Ｒ_１は水素原子またはメチル基を表し、Ｒ_２は炭素数１〜１４のアルキル基またはアラルキル基を表す。Ｒ_２のアルキル基、アラルキル基には炭素数１〜１０のアルコキシ基が結合していてもよい。） (a): (meth) acrylate represented by the following formula (a)

(Wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group or an aralkyl group having 1 to 14 carbon atoms. The alkyl group or aralkyl group of R ₂ represents an alkoxy group having 1 to 10 carbon atoms. May be bonded.)

(b): a monomer containing at least two olefinic double bonds in the molecule

The acrylic resin composition of the present invention is excellent in flexibility and has excellent adhesion to optical films and the like. A composition obtained by blending the acrylic resin composition with a curing agent and / or a silane compound is suitable as a pressure-sensitive adhesive. The optical laminated body of the present invention comprising an optical film and an optical film with an adhesive comprising the adhesive, for example, a glass substrate of a liquid crystal cell, the adhesive layer is subjected to stress caused by a dimensional change of the optical film under wet heat conditions. Due to absorption and relaxation, local stress concentration is reduced, and peeling of the pressure-sensitive adhesive layer from the glass substrate is suppressed. In addition, since optical defects due to non-uniform stress distribution are prevented, display unevenness such as white spots and color unevenness is suppressed. Furthermore, because of the excellent reworkability, even if the optical film with the adhesive once laminated is peeled off from the glass substrate of the optical laminate, glue residue and fogging are suppressed on the surface of the glass substrate after peeling, and again, the glass substrate Can be used as
In particular, the acrylic resin composition of the present invention, a pressure-sensitive adhesive obtained by blending, for example, an isocyanate-based compound and an organic amine compound as a cross-linking agent, can prepare an optical film with a pressure-sensitive adhesive in a short time aging, The optical laminated body containing (1) suppresses floating between the glass substrate and the pressure-sensitive adhesive layer and foaming in the pressure-sensitive adhesive layer, and is excellent in reworkability.

（式中、Ｒ_１は水素原子またはメチル基を表し、Ｒ_２は炭素数１〜１４のアルキル基またはアラルキル基を表す。Ｒ_２のアルキル基、アラルキル基には炭素数１〜１０のアルコキシ基が結合していてもよい。） Hereinafter, the present invention will be described in detail.
The monomer (a) used in the acrylic resins (1) and (2) of the present invention is a (meth) acrylic ester represented by the formula (a).

(Wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group or an aralkyl group having 1 to 14 carbon atoms. The alkyl group or aralkyl group of R ₂ represents an alkoxy group having 1 to 10 carbon atoms. May be bonded.)

Here, as the monomer (a), for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, iso-octyl acrylate, lauryl acrylate Acrylates such as stearyl acrylate, cyclohexyl acrylate, benzyl acrylate, methoxyethyl acrylate and ethoxymethyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl Methacrylate, iso-octyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexylmethacrylate Acrylate, benzyl methacrylate, it can be mentioned methacrylic acid esters such as methoxyethyl methacrylate and ethoxyethyl methacrylate and the like.
Two or more different monomers (a) may be used as the monomer (a).

The content of the structural unit (structural unit (a)) derived from the monomer (a) in the acrylic resin (1) of the present invention is usually 65 to 99 based on 100 parts by weight of the acrylic resin (1). It is about 85 parts by weight, preferably about 70 to 95 parts by weight.
The content of the structural unit (structural unit (a)) derived from the monomer (a) in the acrylic resin (2) is usually 65 to 100 parts by weight based on 100 parts by weight of the acrylic resin (2). Parts.

The monomer (b) used in the acrylic resin (1) of the present invention is a monomer containing at least two olefinic double bonds in the molecule. Due to the presence of the monomer (b), the main chain composed of the structural unit (a) of the acrylic resin (1) is crosslinked.
Specific examples of the monomer (b) include, as a monomer containing two olefinic double bonds in the molecule (bifunctional monomer), 1,4-butanediol di (meth) acrylate, , 6-hexanediol (meth) diacrylate, 1,9-nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol Monomers having two (meth) acryloyl groups in the molecule such as di (meth) acrylate, bis (meth) acrylamides such as methylenebis (meth) acrylamide and ethylenebis (meth) acrylamide, divinyl adipate, divinyl sebacate Divinyl esters such as allyl methacrylate Over DOO, and divinylbenzene. Further, as a monomer containing three olefinic double bonds in the molecule (trifunctional monomer), 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, triallylamine, N, N-diallylacrylamide and the like. Monomers containing four olefinic double bonds in the molecule (tetrafunctional monomers) include tetramethylolmethanetetraacrylate, tetraallyl pyromellitate, N, N ′, N′-tetraallyl-1,4-diaminobutane, tetraallylammonium salt and the like can be mentioned. As the monomer (b), two or more different types of monomers (b) may be used.

（式中Ｒ_３は水素原子またはメチル基を表す。） Among the monomers (b), a bifunctional monomer is preferable, and a monomer having two (meth) acryloyl groups in a molecule as represented by the following formula (B) is particularly preferable.

(In the formula, R ₃ represents a hydrogen atom or a methyl group.)

  The content ([b-1]) of the structural unit derived from the monomer (b) in the acrylic resin (1) is 0.05 to 5 parts by weight with respect to 100 parts by weight of the acrylic resin (1). Preferably it is about 0.1 to 3 parts by weight. When [b-1] is at least 0.05 part by weight, the effect of improving the white spot phenomenon occurring during the production of the optical laminate tends to be improved. This is preferable because the formation of a gel when producing a resin tends to be suppressed.

The acrylic resin (2) used in the present invention is a linear acrylic resin containing the structural unit (a) as a main component, in other words, an acrylic resin containing substantially no structural unit (b). The acrylic resin which does not substantially contain the structural unit (b) will be specifically described. The acrylic resin (1) according to the present invention contains the structural unit (a) as an essential component. An acrylic resin containing, as an optional component, a structural unit (b) whose content (weight) is 1/5 or less. That is, the content of the structural unit (b) in the acrylic resin (2) ([b-2]) and the content of the structural unit (b) in the acrylic resin (1) used simultaneously as the acrylic resin composition ([b -1]) means that it is represented by the following formula.
[B-2] / [b-1] ≦ 1/5

In particular, the content of the structural unit (b) in the acrylic resin (2) is preferably 0.02 parts by weight or less, more preferably 0.01 part by weight or less based on 100 parts by weight of the acrylic resin (2).
It is preferable that the acrylic resin (2) is a linear acrylic resin, since there is a tendency that the separation between the pressure-sensitive adhesive layer containing the acrylic resin composition of the present invention and the glass substrate tends to be suppressed.

  The acrylic resin (1) and / or (2) used in the present invention includes a polar functional group such as a carboxyl group, a hydroxyl group, an amide group, an epoxy group, an aldehyde group, an isocyanate group, and one olefinic double bond. It is recommended to contain a structural unit (structural unit (c)) derived from the monomer (c) containing in the molecule: In particular, it is preferable that the acrylic resin (2) contains the structural unit (c). The polar functional group of the structural unit (c) is preferable because it crosslinks with a crosslinking agent described below.

Specific examples of the monomer (c) include, as the monomer (c) in which the polar functional group is a carboxyl group, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, and the like. Examples of the monomer (c) which is a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Examples of the monomer (c) in which the polar functional group is an amide group include acrylamide, methacrylamide, N, N-dimethylaminopropylacrylamide, diacetonediamide, N, N-dimethylacrylamide, N, N- Examples of the monomer (c) in which the polar functional group is an epoxy group include glycidyl acrylate, glycidyl methacrylate, and the like, and examples of the monomer (c) in which the polar functional group is an oxetanyl group include diethyl acrylamide and N-methylol acrylamide. As the monomer (c), for example, oxetanyl (meth) acrylate, 3-oxetanylmethyl (meth) acrylate, (3-methyl-3-oxetanyl) methyl (meth) acrylate, (3-ethyl-3-oxetanyl) methyl ( (Meth) acrylate and the like. Furthermore, examples of the monomer (c) in which the polar functional group is an amino group include N, N-dimethylaminoethyl acrylate, allylamine, and the like, and the monomer (c) in which the polar functional group is an isocyanate group Examples thereof include 2-methacryloyloxyethyl isocyanate. Examples of the monomer (c) in which the polar functional group is an aldehyde group include, for example, acrylaldehyde.
As these monomers (c), two or more different monomers (c) may be used in combination.

The content of the structural unit (c) contained in the acrylic resin (2) is usually about 0.05 to 20 parts by weight, preferably 0.1 to 20 parts by weight, per 100 parts by weight of the acrylic resin (2). It is about 15 parts by weight. When the content of the structural unit (c) is 0.05 parts by weight or more, the cohesive force of the obtained resin tends to improve, and when the content is 20 parts by weight or less, the content of the optical film and the pressure-sensitive adhesive layer is It is preferable because the peeling-off tends to be suppressed.
The content of the structural unit (c) contained in the acrylic resin (1) is usually about 0 to 20 parts by weight based on 100 parts by weight of the acrylic resin (1). It is preferable that the content of the structural unit (c) be 20 parts by weight or less, because the floating between the glass substrate and the pressure-sensitive adhesive layer tends to be suppressed.
As the structural unit (c), a monomer (c) in which the polar functional group is a hydroxyl group or a carboxyl group is preferable.

  When producing the acrylic resins (1) and (2) used in the present invention, the acrylic resins (1) and (2) may be polymerized together with a vinyl monomer (d) different from any of the monomers (a) to (c). Examples of the vinyl monomer include fatty acid vinyl ester, vinyl halide, vinylidene halide, aromatic vinyl, (meth) acrylonitrile, and conjugated diene compound.

Here, examples of the fatty acid vinyl ester include vinyl acetate, vinyl propionate, vinyl citrate, vinyl 2-ethylhexanoate, vinyl laurate and the like.
Examples of the vinyl halide include vinyl chloride and vinyl bromide. Examples of the vinylidene halide include vinylidene chloride. Examples of the (meth) acrylonitrile include acrylonitrile and methacrylonitrile.
The conjugated diene compound is an olefin having a conjugated double bond in the molecule, and specific examples include isoprene, butadiene, and chloroprene.
Aromatic vinyl is a compound having a vinyl group and an aromatic group, and specific examples thereof include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, and hexyl. Styrene monomers such as styrene, heptylstyrene, octylstyrene, fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene, nitrostyrene, acetylstyrene and methoxystyrene, and nitrogen-containing aromatics such as vinylpyridine and vinylcarbazole Vinyl and the like. As these vinyl monomers (d), two or more different monomers (d) may be used in combination.

The structural unit (d) derived from the monomer (d) contained in the acrylic resin (1) is usually 5 parts by weight or less based on 100 parts by weight of all the structural units constituting the acrylic resin (1). It is preferably 0.05 part by weight or less, particularly preferably substantially not contained.
The structural unit (d) contained in the acrylic resin (2) is usually 5 parts by weight or less, preferably 0.05 part by weight or less, based on 100 parts by weight of all structural units constituting the acrylic resin (2). Particularly preferably, it is preferable that it is not substantially contained.

  Examples of the method for producing the acrylic resins (1) and (2) used in the present invention include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method. In the production of an acrylic resin, a polymerization initiator is usually used. The polymerization initiator is used in an amount of about 0.001 to 5 parts by weight based on 100 parts by weight of the total of all the monomers used for producing the acrylic resin.

  Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone. No. Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), and 1,1′-azobis (cyclohexane-1-carbonitrile). , 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis (2-methylpro Azo compounds such as pionate) and 2,2′-azobis (2-hydroxymethylpropionitrile); lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butylperoxybenzoate, cumene hydroper Oxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, te organic peroxides such as t-butylperoxyneodecanoate, tert-butylperoxypivalate and (3,5,5-trimethylhexanoyl) peroxide; inorganic peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide Oxides and the like. Further, a redox initiator using a thermal polymerization initiator and a reducing agent in combination may be used as the polymerization initiator.

As a method for producing the acrylic resins (1) and (2), a solution polymerization method is particularly preferable. As a specific example of the solution polymerization method, the monomers (a) to (c), and, if necessary, the monomer (d), and an organic solvent are mixed, and under a nitrogen atmosphere, a polymerization initiator is added. A method of adding and stirring at about 40 to 90 ° C., preferably about 60 to 80 ° C. for about 3 to 10 hours is exemplified. Further, in order to control the reaction, the monomer or polymerization initiator to be used may be added during the polymerization, or may be added after being dissolved in an organic solvent.
Here, examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol; methyl ethyl ketone and methyl isobutyl ketone And the like.

The viscosity (25 ° C.) of the solution obtained by diluting the acrylic resin (1) thus obtained to a solid content of 30% with ethyl acetate is usually 10 Pa · s or less, preferably 5 Pa · s or less. is there. If the viscosity of the acrylic resin (1) is 10 Pa · s or less, even if the dimensions of the optical film change, the pressure-sensitive adhesive layer fluctuates following the dimensional changes. This is preferable because there is no difference between the brightness and the brightness of the portion, and display unevenness such as white spots and color unevenness tends to be suppressed. As the molecular weight of the acrylic resin (1), the weight average molecular weight determined by the light scattering method of gel permeation chromatography (GPC) is usually 5 × 10 ⁵ or more, preferably 1 × 10 ⁶ or more. When the weight average molecular weight is 5 × 10 ⁵ or more, the adhesiveness under high temperature and high humidity is improved, the peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be reduced, and the reworkability is improved. This is preferred because of the tendency.

Regarding the molecular weight of the acrylic resin (2), the weight average molecular weight by a light scattering method of gel permeation chromatography (GPC) is usually 1 × 10 ⁶ or more, preferably 2 × 10 ⁶ to 1 × 10 ^7. It is. When the weight average molecular weight is 1 × 10 ⁶ or more, the adhesiveness under high temperature and high humidity is improved, the peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be reduced, and the reworkability is improved. This is preferred because of the tendency. When the weight average molecular weight is 1 × 10 ⁷ or less, even if the dimensions of the optical film change, the pressure-sensitive adhesive layer fluctuates following the dimensional changes. This is preferable because there is no difference between the two and the display unevenness such as white spots and color unevenness tends to be suppressed.

  The acrylic resin of the present invention is a resin composition containing the acrylic resin (1) and the acrylic resin (2) thus obtained. The method for producing the acrylic resin is usually the acrylic resin (1) and the acrylic resin (2). Are separately produced and then mixed, but after producing either the acrylic resin (1) or the acrylic resin (2), a different acrylic resin may be produced in the presence of the produced acrylic resin. After mixing the acrylic resins (1) and (2), the mixture may be diluted with an organic solvent.

  The weight ratio (solid content) of the acrylic resin (1) and the acrylic resin (2) in the acrylic resin composition was 100 parts by weight of the acrylic resin (1) and the acrylic resin (2) in total. ) Is usually at least 5 parts by weight, preferably about 10 to 60 parts by weight. When the acrylic resin (1) is more than 5 parts by weight, even if the dimensions of the optical film change, the pressure-sensitive adhesive layer changes following the dimensional changes. This is preferable because there is no difference between brightness and brightness, and display unevenness such as white spots and color unevenness tends to be suppressed.

  The viscosity of the solution (25 ° C.) obtained by adjusting the solid content of the acrylic resin composition to 30 wt% with ethyl acetate is preferably 10 Pa · s or less, and more preferably 1 to 5 Pa · s. When the viscosity is 10 Pa · s or less, the adhesiveness under high temperature and high humidity is improved, the peeling between the glass substrate and the pressure-sensitive adhesive layer tends to be reduced, and the reworkability tends to be improved. It is preferable because of its existence.

  The acrylic resin composition of the present invention may be used as it is for a pressure-sensitive adhesive, an adhesive, a paint, a thickener, and the like. Further, a composition obtained by blending a crosslinking agent and / or a silane-based compound with an acrylic resin is suitable as the pressure-sensitive adhesive. Here, the cross-linking agent is a compound having two or more functional groups capable of cross-linking with a polar functional group in a molecule, and specifically, an isocyanate compound, an epoxy compound, a metal chelate compound, an aziridine compound, and the like. Is exemplified.

  Here, the isocyanate-based compound includes, for example, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, Examples include phenylmethane triisocyanate and polymethylene polyphenyl isocyanate. The crosslinking agent of the present invention is also an adduct obtained by reacting the isocyanate compound with a polyol such as glycerol or trimethylolpropane, or a dimer or trimer of an isocyanate compound.

  Examples of the epoxy compound include bisphenol A type epoxy resin, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, and trimethylolpropanetriene. Glycidyl ether, diglycidylaniline, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, and the like.

  Examples of the metal chelate compound include compounds in which acetylacetone or ethyl acetoacetate is coordinated with a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. No.

  Examples of aziridine compounds include, for example, N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxide), N, N'-toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine , Bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-hexamethylene-1,6-bis (1-aziridinecarboxide), trimethylolpropane- Tri-β-aziridinyl propionate and tetramethylolmethane-tri-β-aziridinyl propionate;

  Two or more crosslinking agents may be used as the crosslinking agent in the pressure-sensitive adhesive of the present invention. The amount of the cross-linking agent (solid content) in the adhesive is usually about 0.005 to 5 parts by weight, and preferably 0.01 to 3 parts by weight, based on 100 parts by weight (solids) of the acrylic resin. It is about. When the amount of the cross-linking agent is at least 0.005 parts by weight, the peeling-off and the reworkability between the optical film and the pressure-sensitive adhesive layer tend to be improved. Since the pressure-sensitive adhesive layer has excellent followability with respect to the dimensional change, display unevenness such as white spots and color unevenness tends to be reduced, which is preferable.

  When only an isocyanate compound is blended as a cross-linking agent, or when only an epoxy compound is blended, an optical laminate obtained by the obtained pressure-sensitive adhesive is preferable because it tends to be excellent in floating and reworkability.

  Examples of the silane-based compound used in the pressure-sensitive adhesive of the present invention include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, and N- (2-aminoethyl) -3-aminopropyl. Methyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2 -(3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and the like. . Two or more silane compounds may be used in the pressure-sensitive adhesive of the present invention.

The amount (solution) of the silane compound used in the pressure-sensitive adhesive is usually about 0.0001 to 10 parts by weight with respect to 100 parts by weight (solid content) of the acrylic resins (1) and (2) in total. Preferably it is used in an amount of 0.01 to 5 parts by weight. It is preferable that the amount of the silane-based compound is 0.0001 parts by weight or more because the adhesion between the pressure-sensitive adhesive layer and the glass substrate is improved. Further, when the amount of the silane-based compound is 10 parts by weight or less, it is preferable because bleed-out of the silane-based compound from the pressure-sensitive adhesive layer is suppressed and cohesive failure of the pressure-sensitive adhesive layer is suppressed.
As the pressure-sensitive adhesive of the present invention, a pressure-sensitive adhesive containing both a crosslinking agent and a silane compound is preferable.

  The pressure-sensitive adhesive of the present invention contains the acrylic resin composition, the crosslinking agent, and / or the silane compound as described above, and contains an organic solvent used before producing the acrylic resin composition. You may. Further, a crosslinking catalyst, a weather resistance stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and the like may be blended in the adhesive.

Above all, when a crosslinking catalyst and a crosslinking agent are blended in the adhesive, the optical film with the adhesive can be prepared by aging for a short time, and the optical laminate including the film is formed between the optical film and the adhesive layer. It is preferable because it suppresses floating and peeling and foaming in the pressure-sensitive adhesive layer, and is excellent in reworkability.
Examples of the crosslinking catalyst include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, triethylenediamine, polyamino resin, and melamine resin.
When an amine compound is used as a cross-linking catalyst in the pressure-sensitive adhesive, an isocyanate-based compound is preferable as the cross-linking agent.

The optical film with a pressure-sensitive adhesive of the present invention is composed of the pressure-sensitive adhesive and the optical film. As a method for producing the film, for example, a pressure-sensitive adhesive diluted with an organic solvent is applied on a release film, The mixture is heated at about 120 ° C. for about 0.5 to 10 minutes to evaporate the organic solvent to obtain an adhesive layer. Then, after laminating the optical film to the pressure-sensitive adhesive layer, in an atmosphere of a temperature of 23 ° C. and a humidity of 50%, it is aged for about 5 to 20 days, and after the crosslinking agent has sufficiently reacted, the release film is peeled off. A method for obtaining an optical film with a pressure-sensitive adhesive; after obtaining a pressure-sensitive adhesive layer in the same manner as described above, a laminate of the obtained release film and the pressure-sensitive adhesive layer is alternated with a release film and a pressure-sensitive adhesive layer. After being combined in multiple layers as described above, in an atmosphere at a temperature of 23 ° C. and a humidity of 50%, the mixture is aged for about 5 to 20 days, and after the crosslinking agent has sufficiently reacted, the release film is peeled off, and an optical film is applied instead. A method of obtaining an optical film with a pressure-sensitive adhesive in combination.
Here, the release film is a base material when forming the pressure-sensitive adhesive layer. It may be a substrate that protects the pressure-sensitive adhesive layer from foreign substances such as dust and dirt during ripening or storage as an optical film with a pressure-sensitive adhesive. As a specific example of the release film, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarylate is used as a base material. And the like).

  The optical film used for the optical film with a pressure-sensitive adhesive of the present invention is a film having optical characteristics, and examples thereof include a polarizing film and a retardation film. A polarizing film is an optical film having a function of emitting polarized light with respect to incident light such as natural light. As the polarizing film, a linear polarizing film having a property of absorbing linearly polarized light having a vibrating surface which is parallel to the optical axis and transmitting linearly polarized light having a vibrating surface which is a vertical surface is parallel to the optical axis. Examples include a polarization separation film that reflects linearly polarized light on a vibrating surface, and an elliptically polarized film in which a polarization film and a later-described retardation film are laminated. Specific examples of the polarizing film include those in which a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol film.

  Retardation film is an optical film having optical anisotropy such as uniaxial or biaxial, for example, polyvinyl alcohol, polycarbonate, polyester, polyarylate, polyimide, polyolefin, polystyrene, polysulfone, polyethersulfone, polyether By stretching a polymer film composed of vinylidene fluoride / polymethyl methacrylate, liquid crystal polyester, acetylcellulose, cyclic polyolefin, saponified ethylene-vinyl acetate copolymer, polyvinyl chloride, etc. to about 1.01 to 6 times. And the resulting stretched film. Among them, a polymer film obtained by uniaxially or biaxially stretching polycarbonate or polyvinyl alcohol is preferable.

  Examples of the retardation film include a uniaxial retardation film, a wide viewing angle retardation film, a low photoelastic modulus retardation film, a temperature compensation type retardation film, an LC film (bar-shaped liquid crystal twist alignment), a WV film (a disc-shaped liquid crystal tilt). Orientation), an NH film (rod-like liquid crystal tilt orientation), a VAC film (completely biaxially oriented retardation film), a newVAC film (a biaxially oriented retardation film), and the like.

  Further, those obtained by further laminating a substrate film (Protective Film) on one side or both sides of these optical films are also suitably used as optical films. As the substrate film, for example, an acrylic resin film different from the acrylic resin of the present invention, an acetylcellulose-based film such as a cellulose triacetate film, a polyester resin film, an olefin resin film, a polycarbonate resin film, a polyetheretherketone resin film, a polysulfone A resin film is exemplified. The substrate film may be blended with an ultraviolet absorber such as a salicylate compound, a benzophenone compound, a benzotriazole compound, a triazine compound, a cyanoacrylate compound, and a nickel complex salt compound. Among the substrate films, an acetylcellulose-based film is preferable.

  The optical laminate of the present invention comprises an optical film with an adhesive and a glass substrate. The optical laminate can be usually manufactured by laminating the pressure-sensitive adhesive layer of the optical film with a pressure-sensitive adhesive and a glass substrate. Here, examples of the glass substrate include a glass substrate of a liquid crystal cell, an antiglare glass, and a glass for sunglasses. Among them, an adhesive layer of an optical film with an adhesive (upper polarizing plate) is bonded to a glass substrate on the upper part of a liquid crystal cell, and another optical film with an adhesive (lower polarizing plate) is attached to a glass substrate below the liquid crystal cell. The optical laminate obtained by laminating the pressure-sensitive adhesive layer is preferred because it can be used as a liquid crystal display device. Examples of the material for the glass substrate include soda lime glass, low alkali glass, and non-alkali glass.

  The optical laminate of the present invention, even after peeling the optical film with the adhesive from the optical laminate, on the surface of the glass substrate that was in contact with the adhesive layer, because almost no fogging or glue residue occurs, it is peeled. The optical film with the adhesive can be easily re-attached to the glass substrate which has been used, that is, it is excellent in reworkability.

  Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified. The solid content was measured by a measuring method according to JIS K-5407. Specifically, the adhesive solution was arbitrarily weighed, placed in a petri dish, dried at 115 ° C. for 2 hours in an explosion-proof oven, and the residual solids weight was expressed as a percentage of the weight of the initially measured solution. is there. The viscosity is a value measured by a Brookfield viscometer at 25 ° C. The weight average molecular weight measurement by GPC light scattering method uses a GPC device equipped with a light scattering photometer and a differential refractometer as a detector, a sample concentration of 5 mg / ml, a sample introduction amount of 100 μml, a column temperature of 40 ° C., and a flow rate of 1 ml / ml. Under conditions of min, tetrahydrofuran was used as an eluate. The measurement of the weight average molecular weight in terms of polystyrene was obtained by measuring the sample and the standard polystyrene under the same GPC conditions and converting the molecular weight from the retention capacity.

<Production example of acrylic resin>
(Polymerization Example 1)
A reactor equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirrer was charged with 233 parts of ethyl acetate, the air in the apparatus was replaced with nitrogen gas, oxygen-free, and the internal temperature was reduced to 70 ° C. The temperature rose. After adding 0.5 parts of azobisisobutyronitrile (hereinafter sometimes referred to as AIBN) as a polymerization initiator, acrylic acid was used as a monomer (a) while maintaining the internal temperature at 65 to 75 ° C. 95 parts of butyl, 1 part of ethylene glycol diacrylate (hereinafter sometimes referred to as EGDA) as monomer (b) and butyl 4-hydroxyacrylate (hereinafter sometimes referred to as 4HBA) as monomer (c). 4 parts of the mixed solution was dropped into the reaction system over 3 hours. Thereafter, the temperature was maintained at 65 to 75 ° C. for 5 hours to complete the reaction. When the weight of the solid content of the obtained acrylic resin solution was adjusted to 30.0%, the viscosity was 263 mPa · s. The weight average molecular weight by GPC light scattering method was about 2,300,000, and the weight average molecular weight in terms of polystyrene was 553,000.

(Polymerization Example 2)
An acrylic resin was produced in the same manner as in Polymerization Example 1 except that the weight of the monomer (b) shown in Table 1 was used. Table 1 shows the obtained viscosities and the results of the light dispersion method and polystyrene conversion as the weight average molecular weight.

(Polymerization Examples 3 and 4)
The weight of the monomer (a) shown in Table 1 was used, and the weight of the monomer (b) shown in Table 1 was used as tripropylene glycol diacrylate (hereinafter sometimes referred to as TPGDA). An acrylic resin was produced in the same manner as in Polymerization Example 1 except that acrylic acid was used as the monomer (c) in the weight shown in Table 1. Table 1 shows the obtained viscosities and the results of the light dispersion method and polystyrene conversion as the weight average molecular weight.

(Polymerization Example 5)
An acrylic resin was produced in the same manner as in Polymerization Example 1 except that the monomer (b) was not used. Table 1 shows the obtained viscosities and the results of the light dispersion method and polystyrene conversion as the weight average molecular weight.

(Polymerization Example 6)
The same reactor as in Polymerization Example 1 was charged with 95 parts of butyl acrylate as monomer (a), 4 parts of 4HBA and 233 parts of ethyl acetate as monomer (c), and the air in the apparatus was replaced with nitrogen gas. Then, after oxygen-free, the internal temperature was raised to 70 ° C. After adding 0.05 parts of AIBN, the reaction was kept at 50 ° C. for 10 hours to complete the reaction. After the obtained reaction product was purified by precipitation with a methanol solvent, the solvent was distilled off and dissolved again with ethyl acetate to obtain an ethyl acetate solution of an acrylic resin having a solid content of 15%.
The results of the obtained viscosity and weight average molecular weight are shown in Table 1.

(Polymerization Example 7)
The reaction was carried out in the same manner as in Polymerization Example 4 except that the reaction temperature was changed to 60 ° C., to obtain an ethyl acetate solution of an acrylic resin having a solid content of 20.1%.
The results of the obtained viscosity and weight average molecular weight are shown in Table 1.

(Polymerization Example 8)
96 parts of ethyl acetate, 98 parts of butyl acrylate as the monomer (a) and 1.1 parts of 4-hydroxybutyl acrylate as the monomer (c) were charged into the same reaction vessel as in Polymerization Example 1, and charged with nitrogen gas. After the air in the apparatus was replaced to be free of oxygen, the internal temperature was raised to 55 ° C. After adding a total amount of a solution of 0.018 part of 2,2′-azobis (2,4-dimethylvaleronitrile), which is a polymerization initiator, in 4 parts of ethyl acetate, the solution was added while keeping the internal temperature at 54 to 56 ° C. Incubated for hours. At this time, the concentration of ethyl acetate was 50%. Thereafter, ethyl acetate is added every three hours so that the concentration of ethyl acetate increases by 5%, and the temperature is maintained for another 3 hours from the time when the ethyl acetate concentration reaches 85%, and the reaction is carried out. Was 15.4% to obtain a solution of an acrylic resin in ethyl acetate.
The results of the obtained viscosity and weight average molecular weight are shown in Table 1.

<Production Example 1 of acrylic resin composition and pressure-sensitive adhesive containing the composition>
(Production Examples of Adhesives Provided in Examples 1 to 6 and Comparative Examples 1 to 4)
(1) and (2) of the acrylic resin solution obtained in the polymerization example were mixed so that the weight of each solid content was the number of parts shown in Table 2, and the weight of the solid content was 30%. An ethyl acetate solution of the acrylic resin composition was prepared.
An isocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Co., 0.1 part (solid content)) as a crosslinking agent was added to a solution in which the weight of the solid content contained in the ethyl acetate solution was 100 parts. And silane-based compound γ-glycidoxypropyltrimethoxysilane (0.2 part) to obtain an adhesive.

(Production Example 2 of Pressure-Sensitive Adhesive Used in Examples 7 to 10 and Comparative Example 5)
(1) and (2) of the acrylic resin solution obtained in the polymerization example were mixed so that the weight of each solid content became the number of parts shown in Table 3, and the solid content was adjusted to 30% by weight. An ethyl acetate solution of the acrylic resin composition was prepared.
An isocyanate compound (trade name: Coronate L, manufactured by Nippon Polyurethane Co., 0.1 part (solid content)) as a crosslinking agent was added to a solution in which the weight of the solid content contained in the ethyl acetate solution was 100 parts. Then, γ-glycidoxypropyltrimethoxysilane (0.2 part), which is a silane-based compound, and triethylenediamine, which is an amine compound, were mixed in the number shown in Table 3 to obtain an adhesive.

<Production Example 1 of Optical Film with Adhesive and Optical Laminate>
(Aged for 14 days: Examples 1 to 6 and Comparative Examples 1 to 4)
The obtained pressure-sensitive adhesive was applied to a release-treated surface of a polyethylene terephthalate film (trade name: PET3811, manufactured by Lintec) using an applicator so that the thickness after drying was 25 μm, and 90 It dried at 1 degreeC for 1 minute, and obtained the sheet-shaped adhesive. Next, a polarizing film (a film obtained by adsorbing iodine on polyvinyl alcohol and having a three-layer structure sandwiched between triacetyl cellulose-based substrate films on both sides) was used as the optical film, and the film obtained above was obtained on the optical film. The surface having the pressure-sensitive adhesive was bonded by a laminator and then aged for 14 days at a temperature of 40 ° C. and a humidity of 50% to obtain an optical film with a pressure-sensitive adhesive provided with a pressure-sensitive adhesive layer. Subsequently, the surface of the pressure-sensitive adhesive layer of the optical film with a pressure-sensitive adhesive was bonded to both surfaces of a glass substrate for a liquid crystal cell (1737, manufactured by Corning Incorporated) so as to form a cross Nicol. The durability and white spots of the optical laminate after storage were stored for 96 hours at 80 ° C. and Dry (condition 1) and for 96 hours at 60 ° C. and 90% RH (condition 2). Was visually observed. The results were classified as described below and summarized in Table 2.

<Production example 2 of optical film with adhesive and optical laminate>
(Aging for 7 days: Examples 7 to 10 and Comparative Example 5)
Except that the aging time of the optical film with an adhesive is 7 days, it was carried out in the same manner as in <Production Example 1 of Optical Film with Adhesive and Optical Laminate>. The durability and appearance of white spots in the optical laminate were visually observed. The results were classified as follows and summarized in Table 3.

<Blankness of optical laminate>
Evaluation of the expression state of white dropout was performed in the following four stages.
◎: No white drop was observed.
: White spots are hardly noticeable.
Δ: White spots are somewhat noticeable.
×: White spots are noticeably observed.

<Durability of optical laminate>
The durability was evaluated in the following four stages.
A: No change in appearance such as floating, peeling, foaming, etc. was observed.
: Little change in appearance such as floating, peeling, foaming, etc. was observed.
Δ: Appearance changes such as floating, peeling and foaming are slightly noticeable.
X: Appearance changes such as floating, peeling and foaming are remarkably observed.

<Reworkability>
The reworkability was evaluated as follows. First, the optical laminate was prepared into a 25 mm × 150 mm test piece. Next, this test piece was stuck on a glass substrate for liquid crystal cells (soda lime glass manufactured by Nippon Sheet Glass Co., Ltd.) using a sticking device (“Lami Packer” manufactured by Fuji Plastics Machinery Co., Ltd.), and was heated at 50 ° C. and 5 kg / cm Autoclave treatment was performed at ² (490.3 kPa) for 20 minutes. Subsequently, after performing a heat treatment at 70 ° C. for 2 hours, the sample was stored in an oven at 70 ° C. for 24 hours, and then the adhesive test piece was subjected to a speed of 300 mm / min in an atmosphere of 23 ° C. and 50% RH. Table 2 and Table 3 show the results of observing the state of the surface of the glass plate classified in the following manner.

The reworkability was evaluated according to the following four stages depending on the state of the glass plate surface.
: No fogging or adhesive residue is observed on the surface of the glass plate.
：: Almost no fogging is observed on the glass plate surface.
Δ: Clouding or the like is observed on the glass plate surface.
×: Adhesive residue is observed on the glass plate surface.

  The acrylic resin composition of the present invention can be used, for example, for an adhesive, an adhesive, a paint, a thickener, and the like. The pressure-sensitive adhesive of the present invention can be used, for example, as a pressure-sensitive adhesive suitable for an optical laminate such as a liquid crystal cell.

Claims (14)

An acrylic resin composition containing the following acrylic resins (1) and (2).
Acrylic resin (1): an acrylic resin containing a structural unit derived from the following (a) (structural unit (a)) and a structural unit derived from the following (b) (structural unit (b)).
Acrylic resin (2): A linear acrylic resin containing the structural unit (a) as a main component.
(a): (meth) acrylate represented by the following formula (A)

(Wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ represents an alkyl group or an aralkyl group having 1 to 14 carbon atoms. The alkyl or aralkyl group of R ₂ is an alkoxy group having 1 to 10 carbon atoms. May be substituted.)
(b): a monomer containing at least two olefinic double bonds in the molecule   The acrylic resin (2) contains, as an optional component, a structural unit (b) that is 1/5 or less of the content (weight) of the structural unit (b) contained in the acrylic resin (1) according to claim 1. The acrylic resin composition according to claim 1, which is an acrylic resin.   The acrylic resin composition according to claim 1 or 2, wherein the content of the structural unit (a) in the acrylic resin (1) is 65 to 99.85 parts by weight based on 100 parts by weight of the acrylic resin (1). The acrylic resin composition according to any one of claims 1 to 3, wherein the acrylic resin (1) and / or (2) further contains a structural unit derived from the following monomer (c).
(c): a molecule comprising at least one polar functional group selected from the group consisting of a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, an oxetanyl group, an aldehyde group and an isocyanate group, and one olefinic double bond. Monomer contained in The acrylic resin composition according to any one of claims 1 to 4, wherein the monomer (b) is a monomer containing at least two (meth) acryloyl groups represented by the following formula (B) in a molecule. .

(In the formula, R ₃ represents a hydrogen atom or a methyl group.)   The acrylic resin composition according to any one of claims 1 to 5, wherein the acrylic resin (2) is 5 to 50 parts by weight based on a total of 100 parts by weight of the acrylic resin (1) and the acrylic resin (2).   An adhesive comprising the acrylic resin composition according to claim 1 and a crosslinking agent and / or a silane compound.   The pressure-sensitive adhesive according to claim 7, further comprising an amine compound as a crosslinking catalyst.   An optical film with an adhesive, comprising the adhesive according to claim 7 and an optical film.   The optical film with a pressure-sensitive adhesive according to claim 9, wherein the optical film is a polarizing film and / or a retardation film.   The optical film with an adhesive according to claim 9 or 10, further comprising a release film laminated on the adhesive layer of the optical film with an adhesive.   An optical laminate comprising the optical film with a pressure-sensitive adhesive according to any one of claims 9 to 11 and a glass substrate.   An optical laminate obtained by peeling a release film from the optical film with a pressure-sensitive adhesive according to claim 11, and laminating a glass substrate on the pressure-sensitive adhesive layer obtained by peeling. An optical laminate obtained by peeling an optical film with an adhesive from the optical laminate according to claim 12 or 13, and then laminating the optical film with an adhesive again on a glass substrate obtained by peeling.