KR20200033735A - Pressure-sensitive adhesive and pressure-sensitive adhesive sheet - Google Patents

Abstract

Provided is an adhesive having excellent adhesion, moist heat whitening, and outgas resistance, and having both bending resistance and excellent pot life. The adhesive comprises: an acrylic copolymer (A) of a mixture including at least, 30 to 60 parts by mass of (meth)acrylic acid alkyl ester (a1) having 1 to 3 carbon atoms in an alkyl group, 15 to 60 parts by mass of (meth)acrylic acid ester (a2) containing a hydroxyl group, and 10 to 50 parts by mass of (meth)acrylic acid alkyl ester (a3) having 4 to 8 carbon atoms in the alkyl group; and a curing agent (B), and meets following requirements. The mixture contains two or more (a2), the total amount of (a1), (a2) and (a3) is 100 parts by mass, and the total amount (parts by mass) of (a1) and (a2) is more than or equal to the amount (parts by mass) of (a3).

Description

Adhesive and adhesive sheet {PRESSURE-SENSITIVE ADHESIVE AND PRESSURE-SENSITIVE ADHESIVE SHEET}

This application claims priority based on Japanese Patent Application No. 2018-175897, filed on September 20, 2018, and includes the entirety of its disclosure herein.

The present invention relates to an adhesive and an adhesive sheet.

2. Description of the Related Art With the recent rapid development of electronic devices, various flat panel displays (FPDs) such as liquid crystal displays (LCDs), plasma displays (PDPs), rear projection displays (RPJs), EL displays, and light emitting diode displays are widely used as display devices. In general, various types of films are used for such display devices, such as an anti-reflection film for preventing reflection of an external light source and a protective film (protective film) for preventing scratching of the surface of the display device. For example, polarizing films and retardation films are used as members for liquid crystal cells used in LCDs.

In addition, FPD is used not only as a display device, but also as an input device such as a touch panel. In the touch panel, films such as a protective film, an antireflection film, and a transparent electrode film are generally used. These films are generally pasted using an adhesive (also called a pressure sensitive adhesive).

International Publication No. 2015/140911

The adhesive used for the use of the touch panel is not only adhesive and transparent, but even when used in a high-temperature and high-humidity environment, no bubbles will occur in the adhesive layer (foaming resistance), and no lifting or peeling will occur in the adhesive film (resistance to peeling) It is required that the adhesive layer itself does not discolor white (non-whitening property).

In addition, since the touch panel is constructed based on the LCD, it is common to use the polarizing plate as an adhesive. This polarizing plate is pasted to a liquid crystal cell using an adhesive. Even when used in harsh environments such as high temperature and high humidity environments, the pressure sensitive adhesive for polarizing plates needs to be compatible with the performance that the polarizing plate does not peel off or lift off from the liquid crystal cell and that does not leak light from the liquid crystal cell to the outside (light leakage prevention). have. In addition, the light leakage of the polarizing plate is because when the LCD is used in a high-temperature and high-humidity environment, the stress caused by the size of the polarizing plate shrinking or expanding cannot be relieved by the adhesive layer, and residual stress originating from the polarizing plate remains. Happens.

In addition, since the touch panel is used in a portable information terminal such as a smartphone, impact resistance is important in consideration of falling. As the base material of the touch panel, a plastic film having high transparency such as polycarbonate (PC), poly methyl methacrylate (PMMA) or cycloolefin (COP) is used. However, since the plastic material with high transparency is hard and has low flexibility, a large amount of plasticizer is blended to obtain desired flexibility, processability, and moldability. However, this plasticizer is a cause, and when the touch panel is used in a high temperature environment, there is a fear that gas is generated between the plastic film and the adhesive layer (also referred to as outgas).

Some pressure-sensitive adhesives for obtaining the pressure-sensitive adhesive layer adjacent to the substrate are known. For example, since the pressure-sensitive adhesive described in Patent Document 1 uses a polyisocyanate compound and a chelating compound in combination, the crosslinking density of the pressure-sensitive adhesive layer to be formed is high, and there is a problem in bending resistance. In addition, since the reaction of the polyisocyanate compound and the (meth) acrylic acid ester copolymer having a hydroxyl group is significantly promoted by the metal contained in the chelating compound, there is also a problem in the coating process that the pot life is short.

The technical problem to be achieved by the present invention is to provide an adhesive having excellent adhesion, moist heat whitening and outgas resistance, flexibility and excellent pot life, and an adhesive sheet using the same.

As a result of repeated studies of the inventors in order to solve the above problems, the present invention has been completed.

That is, in one embodiment according to the present invention, at least 30 to 60 parts by mass of (meth) acrylic acid alkyl ester (a1) having 1 to 3 carbon atoms in the alkyl group, and 15 to 60 masses of hydroxyl group-containing (meth) acrylic acid ester (a2) An adhesive comprising an acrylic copolymer (A) and a curing agent (B) of a mixture containing 10 to 50 parts by mass of (meth) acrylic acid alkyl ester (a3) having 4 to 8 carbon atoms of the part and alkyl group, and satisfying the following requirements to be.

The mixture contains two or more (a2).

The total amount of (a1), (a2) and (a3) is 100 parts by mass.

The total amount (parts by mass) of (a1) and (a2) ≥ (a3) is the amount (parts by mass).

Preferably, the molecular weight dispersion degree of the acrylic copolymer (A) is 5.5 to 15.

In one embodiment, the curing agent (B) comprises an isocyanate curing agent (B-1).

In the above example, preferably, the isocyanate curing agent (B-1) is a reaction product of an isocyanate compound having three or more isocyanato groups and alcohol, and includes an isocyanate curing agent having two or more isocyanato groups, and an isocyanate curing agent. The blending amount of (B-1) is 0.01 to 0.4 parts by mass based on 100 parts by mass of the acrylic copolymer (A).

In another embodiment, the curing agent (B) includes a metal chelate curing agent (B-2), and the blending amount of the metal chelate curing agent (B-2) is 0.1 to 5 parts by mass based on 100 parts by mass of the acrylic copolymer (A). .

In addition, another embodiment according to the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer that is a cured product of the substrate and the pressure-sensitive adhesive.

In addition, another embodiment according to the present invention is a pressure-sensitive adhesive sheet having a peelable sheet and a pressure-sensitive adhesive layer that is a cured product of the pressure-sensitive adhesive.

According to the present invention, it is possible to provide a pressure-sensitive adhesive having excellent adhesion, moist heat whitening and outgas resistance, flexibility and excellent pot life, and a pressure-sensitive adhesive sheet using the same.

Hereinafter, the present invention will be described in detail. In addition, in the present specification, in particular, the term "(meth) acrylic", "(meth) acryloyl", "(meth) acrylic acid", "(meth) acrylate", and "(meth) acryloyloxy" "Acrylic or methacrylic", "acryloyl or methacryloyl", "acrylic acid or methacrylic acid", "acrylate or methacrylate", "acryloyloxy or methacryloyl oxide", respectively, unless otherwise specified. Poetry ”. In addition, "part" and "%" represent "mass part" and "mass%", respectively, unless otherwise specified.

<Acrylic copolymer (A)>

The acrylic copolymer (A) used in the present invention has at least 1 to 3 carbon atoms in the alkyl group (meth) acrylic acid alkyl ester (a1), hydroxyl group-containing (meth) acrylic acid ester (a2) and 4 to 8 carbon atoms in the alkyl group. It is a copolymer of a mixture containing (meth) acrylic acid alkyl ester (a3).

The mixture includes (a1) 30-60 parts (a2) 15-60 parts and (a3) 10-50 parts when the total amount of (a1), (a2) and (a3) is 100 parts. The total amount (parts by mass) of (a1) and (a2) ≥ (a3) is the amount (parts by mass). The mixture contains two or more (a2).

<(Meth) acrylic acid alkyl ester having 1 to 3 carbon atoms in alkyl group (a1)>

The lower limit of the glass transition temperature (Tg) of the (meth) acrylic acid alkyl ester (a1) homopolymer having 1 to 3 carbon atoms in the alkyl group is preferably -40 ° C or higher, more preferably -30 ° C or higher, and more preferably -25 ° C or higher This is more preferred. The upper limit is preferably 100 ° C or lower, more preferably 70 ° C or lower, and even more preferably 50 ° C or lower. When the glass transition temperature (Tg) of the homopolymer is within the above range, adhesion and outgas resistance are further improved. In addition, Tg referred to here is a numerical value described in "Polymer Handbook, Fourth Edition", J. Brandrup, E. H. Immergut, and E. A. Grulke (1999).

The (meth) acrylic acid alkyl ester (a1) having 1 to 3 carbon atoms in the alkyl group is composed of (a1), (a2), (a3) and, if necessary, other (meth) acrylic acid esters. 30 to 60 parts by mass of 100 parts by mass can be used. The lower limit of the amount used is preferably 35 parts by mass, more preferably 40 parts by mass. The upper limit is preferably 55 parts by mass, more preferably 50 parts by mass. By using 30 to 60 parts by mass of (meth) acrylic acid alkyl ester (a1), the outgas resistance is improved, and the adhesion can be improved. (a1) is specifically methyl acrylate, (meth) ethyl acrylate, propyl acrylate, or isopropyl (meth) acrylate. Particularly, methyl acrylate is preferred in terms of outgas resistance. These may be used alone or in combination of two or more.

<The hydroxyl group-containing (meth) acrylic acid ester (a2)>

In addition to the (meth) acrylic acid alkyl ester (a1), two or more hydroxyl group-containing (meth) acrylic acid esters (a2) are used for the synthesis of the acrylic copolymer (A). (a2) is used in a total of 15 to 60 parts by mass in two types based on 100 parts by mass of the total monomers.

<A hydroxyl group-containing (meth)acrylic acid ester (a2-1) having a carbon number of 3 or less or a hydroxyl group-containing alkyl chain>

One of the hydroxyl group-containing (meth) acrylic acid esters (a2) is a hydroxyl group-containing (meth) acrylic acid ester (a2-1) having a hydroxyl group-containing alkyl chain having 3 or less or secondary hydroxyl groups. The lower limit of the amount used for 100 parts by mass of all the monomers (a2-1) is preferably 10 parts by mass, more preferably 20 parts by mass. The upper limit is preferably 59.8 parts by mass, more preferably 50 parts by mass. Thereby, the affinity with water is improved and the moist heat whitening resistance is improved. In addition, adhesion to a highly polar adherend such as metal, glass and plastic is improved. Specifically, 2-hydroxy ethyl (meth) acrylate, 2-hydroxy propyl (meth) acrylate, 3-hydroxy propyl (meth) acrylate, 2-hydroxy butyl (meth) acrylate and 3- And hydroxy butyl (meth) acrylate.

<A hydroxyl group-containing alkyl chain has 4 or more carbon atoms and a hydroxyl group-containing (meth)acrylic acid ester (a2-2)>

The other of the hydroxyl group-containing (meth) acrylic acid ester (a2) is a hydroxyl group-containing (meth) acrylic acid ester (a2-2) having 4 or more carbon atoms in the hydroxyl group-containing alkyl chain. The lower limit of the amount used for 100 parts by mass of all the monomers (a2-2) is preferably 0.2 parts by mass or more, and more preferably 1 part by mass. The upper limit is preferably 5 parts by mass, more preferably 3 parts by mass. Accordingly, the reaction between the acrylic copolymer (A) and the curing agent (B) can be adjusted and the degree of crosslinking can be appropriately adjusted. Specifically, 4-hydroxy butyl (meth) acrylate, 6-hydroxy hexyl (meth) acrylate, 8-hydroxy octyl (meth) acrylate, etc. are mentioned.

<(Meth) acrylic acid alkyl ester having 4 to 8 carbon atoms in alkyl group (a3)>

In the synthesis of the acrylic copolymer (A), a (meth) acrylic acid alkyl ester (a3) having 4 to 8 carbon atoms in the alkyl group is used. The lower limit of the amount of (a3) used for 100 parts by mass of the total monomers is preferably 15 parts by mass, more preferably 25 parts by mass. The upper limit is preferably 45 parts by mass, more preferably 40 parts by mass. Specifically, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate And (meth) acrylic acid cyclic alkyl esters such as cyclohexyl (meth) acrylate. Of these (meth) acrylic acid alkyl esters (a3), butyl (meth) acrylate is particularly preferred because it is easy to control the polymerization average molecular weight and to obtain a suitable viscosity. These may be used alone or in combination of two or more.

<Ethylene-based unsaturated monomer including other (meth) acrylic acid ester>

The acrylic copolymer (A) is a monomer constituting the copolymer, and if necessary, may include other ethylenically unsaturated monomers other than the (meth) acrylic acid alkyl ester. Specifically, nitrogen-containing (meth) acrylic acid esters such as acrylamide; Alkoxy-based (meth) acrylic acid esters such as methoxy ethyl acrylate; And vinyl-based monomers such as vinyl acetate.

The acrylic copolymer (A) can be obtained by radically polymerizing the whole monomers described above using a radical polymerization initiator. The acrylic copolymer (A) can be synthesized by polymerization methods such as solution polymerization, emulsion polymerization, and suspension polymerization. Among these polymerization methods, solution polymerization is preferred from the viewpoint of transparency and adhesion. In the case of solution polymerization, it is preferable to perform polymerization in the presence of a solvent such as ethyl acetate, toluene, xylene, anisole, methyl ethyl ketone and cyclohexanone. The radical polymerization temperature is preferably in the range of 60 to 120 ° C, and the polymerization time is preferably 3 to 10 hours.

A well-known thing can be used as a radical polymerization initiator, and if it is a compound which can generate a radical under conditions of polymerization temperature, there is no particular limitation. For example, dialkyl peroxides, peroxy esters, ketone peroxides, peroxy ketals, diacyl peroxides, organic peroxides and azo compounds.

As an azo compound, 2,2'-azobis butyronitrile, such as 2,2'-azobis isobutyronitrile (abbreviation: AIBN) and 2,2'-azobis (2-methyl butyronitrile); 2,2'-azobis ballet such as 2,2'-azobis (4-methoxy-2,4-dimethyl valero nitrile) and 2,2'-azobis (2,4-dimethyl valero nitrile) Nitriles; 2,2'-azobis propionitriles such as 2,2'-azobis (2-hydroxy methyl propionitrile); 1,1'-azobis-1-alkane nitriles such as 1,1'-azobis (cyclohexane-1-carbonitrile) can be used. These are used alone or in combination of two or more.

The radical polymerization initiator is preferably used in an amount of 0.001 to 5 parts, more preferably 0.01 to 2 parts, per 100 parts of an ethylenically unsaturated monomer.

As a chain transfer agent, a well-known thing can be used, and if it is a compound which can control molecular weight and molecular weight dispersion degree (Mw / Mn), there is no restriction | limiting in particular. For example, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, mercapto ethanol, thioglycerol, thioglycolic acid, 2-mer Mercaptans such as capto propionic acid, 3-mercapto propionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercapto propionic acid, 2-mercapto ethane sulfonic acid and butyl thio glycolate; Disulfides such as dimethyl chitogen disulfide, diethyl chitogen disulfide, diisopropyl chitogen disulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide and tetrabutyl thiuram disulfide; Halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, bromoform, bromo trichloroethane, carbon tetrabromide and ethylene bromide; Secondary alcohols such as isopropanol and glycerin; Phosphorous acid, hypophosphite and its salts (such as sodium hypophosphite and potassium hypophosphite) and sulfurous acid, hydrogen sulfite, dithiothic acid, metabisulfite and its salts (sodium hydrogen sulfite, potassium hydrogensulfite, sodium dithionate, sodium Lower fatty acids such as potassium dithionate, sodium metabisulfite and potassium metabisulfite, and salts thereof; Aryl alcohol; 2-ethyl hexyl thio glycolate; α-methylstyrene dimer; Terpinolene; α-pinene, γ-pinene; Dipentene; And anisole. These are used alone or in combination of two or more.

The amount of the chain transfer agent is preferably 0.5 to 5 parts based on 100 parts of the ethylenically unsaturated monomer.

The weight average molecular weight of the acrylic copolymer (A) is preferably 200,000 or more, more preferably 400,000 or more, and more preferably 600,000 or more. 1 million or less is preferable, 950000 or less is more preferable, and 900,000 or less is more preferable. By setting the weight average molecular weight within the above range, the tackiness and outgassing resistance are further improved.

The molecular weight dispersion degree (Mw / Mn) showing the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer (A) is preferably 5.5 or more, more preferably 6 or more, and more than 6.5 It is more preferable. 15 or less is preferable, 12 or less is more preferable, and 10 or less is still more preferable. By setting this molecular weight dispersion degree to 5.5-15, adhesiveness and outgas resistance are further improved. In addition, the weight average molecular weight and the number average molecular weight are polystyrene conversion values measured by gel permeation chromatography (GPC).

Two or more types of acrylic copolymers (A) can be used.

The raw material mixture of the acrylic copolymer (A) needs to satisfy the total amount (parts by mass) of (a1) and (a2) ≥ (a3) (parts by mass). This makes it possible to achieve both outgas resistance and moist heat whitening resistance.

<Curing agent (B)>

The curing agent (B) preferably contains an isocyanate curing agent (B-1) or a metal chelate curing agent (B-2).

<Isocyanate curing agent (B-1)>

As the isocyanate curing agent (B-1), an isocyanate-based curing agent having two or more isocyanate groups such as aromatic polyisocyanate, aliphatic polyisocyanate, aromatic aliphatic polyisocyanate, and alicyclic polyisocyanate is preferable.

Examples of aromatic polyisocyanates are 1,3-phenylene isocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene isocyanate, 4,4'-diphenyl methane diisocyanate, 2,4- Trilene isocyanate, 2,6-trilene isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianidine diisocyanate, 4,4 And '-diphenyl diisocyanate and 4,4' 4 "-triphenyl methane triisocyanate.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (aka HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, and 2,3-butylene diisocyanate. , 1,3-butylene diisocyanate, deca methylene diisocyanate, 2,4,4-trimethyl hexamethylene diisocyanate, and the like.

Aromatic aliphatic polyisocyanates include, for example, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1, And 4-diethylbenzene 1,4-tetramethyl xylene diisocyanate and 1,3-tetramethyl xylene diisocyanate.

As the alicyclic polyisocyanate, for example, 3-isocyanate methyl-3,5,5-trimethyl cyclohexyl isocyanate (aka IPDI, isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclo Hexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and 1, 4-bis (isocyanate methyl) cyclohexane, etc. are mentioned.

Moreover, the burette body, the nurate body, and the adduct body of the said polyisocyanate are mentioned.

The burette body is a self-condensation product having a burette bond in which the isocyanate monomer is self-condensed, for example, a burette body of hexamethylene diisocyanate (Smidule N-75, manufactured by Sumika Covestro, Urethane; Duranate 24A-90CX) , Asahi Kasei Co .; NP-1200, manufactured by Mitsui Kagaku).

The nurate body is a trimer of the above-described isocyanate monomer, and for example, a trimer of hexamethylene diisocyanate (Smidule N-3300, manufactured by Sumika Covestro Urethane; Coronate HX, manufactured by Tosoh Corporation; Duranate TPA100 Asahi Kasei) Manufactured by D-172, manufactured by Mitsui Chemical Co., Ltd., a trimer of isophorone diisocyanate (VESTANAT T-1890, manufactured by Evonik Degusa Japan; Death Module Z-4370, manufactured by Sumika Covestro Urethane) and trilene isocyanate 3 And a monomer (Coronate 2031, manufactured by Tosoh Corporation).

The adduct is an isocyanate compound having two or more isocyanato groups (an isocyanate compound having two or more functionalities) formed by reacting the isocyanate monomer with a low-molecular-active hydrogen-containing compound. For example, as an isocyanate compound having three isocyanato groups (trifunctional isocyanate compound), a compound obtained by reacting trimethylol propane with hexamethylene diisocyanate (Coronate HL, manufactured by Tosoh Corporation; Semidule HT, Smica Covestro) Urethane Corporation; Takenate D-160N, manufactured by Mitsui Chemicals), trimethylolpropane and reylene isocyanate are reacted with compounds (Coroneto L, manufactured by Tosoh Corporation; Sumi Module L-75, manufactured by Sumika Covestro Urethane), trimethylolpropane and And compounds (Takenate D-140N, manufactured by Mitsui Kagaku Co., Ltd.) which react xylene-range isocyanate to react compounds (Takenate D-110N, manufactured by Mitsui Chemical Co., Ltd.) and trimethylol propane and isophorone diisocyanate. As the bifunctional isocyanate compound, an allophanate compound made of 1,6-hexamethylene diisocyanate and mono alcohol (Duranate D-201, manufactured by Asahi Kasei; Coronate 2770, manufactured by Tosoh Corporation; D-178NL, manufactured by Mitsui Chemical Co., Ltd.) ) And the like.

Here, examples of the low-molecular-active hydrogen-containing compound include aliphatic or alicyclic diols, trifunctional polyols, polyfunctional polyols, aromatic diols, aliphatic polyamines, aromatic polyamines, and polythiols. Specifically, 2-butyl-2-ethyl-1,3-propane diol (TMP), 1,1,1-trimethylol propane, ethylene dithiol, etc. may be mentioned.

Among the isocyanate curing agents (B-1), a bifunctional or higher isocyanate compound is preferable because it can form a sufficient crosslinked structure. Also, considering the substrate adhesion and outgas resistance, the adduct body is preferred, trimethylol propane adduct of hexamethylene diisocyanate, trimethylol propane adduct of trilene isocyanate, trimethylol propane of isophorone diisocyanate Trifunctional isocyanate compounds such as an adduct and a trimethylol propane adduct of xylene diisocyanate; Preference is given to allophanate compounds made of 1,6-hexamethylene diisocyanate and mono alcohols. These isocyanate curing agents (B-1) may be used singly or in combination of two or more kinds.

<Terminal sealing type isocyanate curing agent>

The isocyanate curing agent (B-1) is an isocyanate compound having three or more isocyanato groups (an isocyanate compound having three or more functional groups) and an alcohol, and an isocyanate curing agent having two or more isocyanato groups (herein, " Terminal encapsulated isocyanate curing agent ") can be suitably used. It is preferable that the terminal encapsulated isocyanate curing agent has a urethane bond connected to an alkyl group. Here, it is preferable that it is monofunctional alcohol (monol), and it is preferable that it is an aliphatic alcohol as alcohol which can react with an isocyanate compound of trifunctional or more. The aliphatic alcohol is preferably a linear or branched aliphatic alcohol, and preferably an aliphatic alcohol having 8 to 22 carbon atoms.

For example, octyl alcohol, nonyl alcohol, decyl alcohol, dodecyl alcohol, tridecyl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, docosyl alcohol, phenol, benzyl alcohol and pen And ethyl alcohol.

The use amount of the isocyanate curing agent (B-1) is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.2 parts by mass or more with respect to 100 parts by mass of the acrylic copolymer (A). 0.4 mass parts or less is preferable, 0.35 mass parts or less is more preferable, and 0.3 mass parts or less is more preferable. By setting it within the said range, outgas resistance is improved.

<Metal chelate curing agent (B-2)>

It is also preferable to use a metal chelate curing agent (B-2) as a curing agent. Metal chelating curing agents include titanium acetyl acetonate, titanium tetraacetyl acetonate, titanium ethyl aceto acetate, zirconium tetraacetyl acetonate and aluminum trisacetyl acetonate. Zirconium tetraacetyl acetonate is preferred in view of adhesion and outgas resistance.

The metal chelate curing agent (B-2) is preferably used in an amount of 0.1 part by mass or more, more preferably 0.5 part by mass or more, and even more preferably 1 part by mass or more with respect to 100 parts by mass of the acrylic copolymer (A). 5 parts by mass or less is preferable, 3 parts by mass or less is more preferable, and 2 parts by mass or less is more preferable. By setting it within the said range, out gas resistance improves.

As another curing agent of the present invention, a polyfunctional epoxy compound may be used in combination within a range that does not impair the effects of the invention. By using together a polyfunctional epoxy compound, the heat resistance of the pressure-sensitive adhesive layer can be further improved. Polyfunctional epoxy compounds include, for example, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and N, N, N'N'-tetraglycidyl-m-xylene diamine And the like.

In the present invention, the polyfunctional epoxy compound is preferably used in an amount of 0.01 to 0.5 parts by mass based on 100 parts by mass of the acrylic copolymer (A).

The pressure-sensitive adhesive of the present invention may also contain a silane coupling agent (C), if necessary. When the silane coupling agent (C) of the present invention is used, adhesion between the pressure-sensitive adhesive layer and the adherend can be improved.

<Silane coupling agent (C)>

As the silane coupling agent (C), for example, γ- (meth) acryloxy methyl trimethoxy silane, γ- (meth) acryloxy propyl trimethoxy silane, γ- (meth) acryloxy propyl triethoxy silane alkoxy silanes having (meth) acryloxy groups such as, γ- (meth) acryloxy propyl tributoxy silane, γ- (meth) acryloxy propyl methyl dimethoxy silane, and γ- (meth) acryloxy propyl methyl diethoxy silane compound; Alkoxy silane compounds having vinyl groups such as vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tributoxy silane and vinyl methyl dimethoxy silane; alkoxy silane compounds having amino alkyl groups such as γ-amino propyl trimethoxy silane, γ-amino propyl triethoxy silane, γ-amino propyl methyl dimethoxy silane, and γ-amino propyl methyl diethoxy silane; γ-mercapto propyl trimethoxy silane, γ-mercapto propyl triethoxy silane, γ-mercapto propyl methyl dimethoxy silane, γ-mercapto propyl methyl diethoxy silane, β-mercapto methyl phenyl ethyl trimethoxy Alkoxy silane compounds having mercapto groups such as silane, mercapto methyl trimethoxy silane, 6-mercapto hexyl trimethoxy silane and 10-mercapto decyl trimethoxy silane; Methyl trimethoxy silane, methyl triethoxy silane, dimethyl dimethoxy silane, dimethyl diethoxy silane, ethyl trimethoxy silane, ethyl triethoxy silane, diethyl dimethoxy silane, diethyl diethoxy silane, hexyl trimethoxy Alkoxy silane compounds having an alkyl group such as silane and decyl trimethoxy silane; Alkoxy silane compounds having phenyl groups such as phenyl trimethoxy silane, phenyl triethoxy silane, phenyl tripropoxy silane, and phenyl tributoxy silane; Alkoxy silane compounds having no substituents such as tetramethoxy silane, tetraethoxy silane, tetra butoxy silane, and tetra propoxy silane; And an alkoxy silane compound having a glycidyl group such as 3-glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl triethoxy silane, and 3-glycidoxy propyl methyl dimethoxy silane. Other alkoxy silane compounds include 2- (3,4-epoxy cyclohexyl) ethyl trimethoxy silane, 2- (3,4-epoxy cyclohexyl) ethyl triethoxy silane, 3-chloropropyl methyl dimethoxy silane, 3-chloropropyl trimethoxy silane, hexa methyl silazane, diphenyl dimethoxy silane, 1,3,5-tris (3-trimethoxy silyl propyl) isocyanurate, secret tris (2-methoxyethoxy ) Silane, N- (2-aminoethyl) -3-aminopropyl methyl dimethoxy silane, N- (2-aminoethyl) -3-aminopropyl trimethoxy silane and 3-isocyanate propyl triethoxy silane. You can.

It is preferable that the silane coupling agent (C) has a silanol group produced by hydrolysis of an alkoxy group in the adhesive layer. When the silane coupling agent (C) takes this form, it becomes easy to be compatible with water that has penetrated into the pressure-sensitive adhesive layer, thereby improving the wet heat whitening resistance of the pressure-sensitive adhesive layer. And it is more preferable that the silane coupling agent (C) moves relatively freely in the pressure-sensitive adhesive layer and is compatible with water. In order to further improve the moist heat whitening resistance, it is more preferable that the silane coupling agent (C) does not have a reactive functional group other than an alkoxy group or has a functional group that is difficult to react with a functional group of the acrylic copolymer (A). For example, it is more preferable to have an alicyclic epoxy group other than the alkoxy group. In addition, the said substrate does not prevent the silane coupling agent (C) from having a reactive functional group other than an alicyclic epoxy group.

Examples of the silane coupling agent having an alicyclic epoxy group include 2- (3,4-epoxy cyclohexyl) ethyl trimethoxy silane, 2- (3,4-epoxy cyclohexyl) ethyl triethoxy silane, and the like. Moreover, the silane coupling agent which does not have a reactive group other than an alkoxy group is the alkoxy silane compound which has the said alkyl group, the alkoxy silane compound which has a phenyl group, and the alkoxy silane compound which does not have a substituent. More preferably 2- (3,4-epoxy cyclohexyl) ethyl trimethoxy silane, methyl triethoxy silane, tetraethoxy silane and phenyl triethoxy silane. The silane coupling agent (C) may be used alone or in combination of two or more.

The amount of the silane coupling agent (C) used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and even more preferably 0.05 part by mass or more with respect to 100 parts by mass of the acrylic copolymer (A). 1 mass part or less is preferable, 0.5 mass part or less is more preferable, and 0.2 mass part or less is more preferable. The silane coupling agent (C) can be used in the above range to further improve adhesion.

In addition to the acrylic copolymer (A) and the curing agent (B), the pressure-sensitive adhesive of the present invention may be used in combination with other resins, for example, polyester resins, amino resins, epoxy resins and polyurethane resins, if necessary. In addition, coupling agents depending on the application; Tackifiers; Fillers such as talc, calcium carbonate and titanium oxide; coloring agent; Emollients; Ultraviolet absorbers; Antioxidants; Antifoaming agent; Light stabilizers; Weathering stabilizer; Curing accelerator; Curing retarder; You may mix | blend additives, such as phosphoric acid ester.

The adhesive sheet of the present invention includes at least an adhesive layer formed from the adhesive composition. The adhesive sheet can be obtained by coating the adhesive with a release liner. Alternatively, it can also be obtained by directly coating an adhesive on a substrate. The pressure-sensitive adhesive sheet can be used as a pressure-sensitive adhesive sheet without a substrate and a so-called cast pressure-sensitive adhesive sheet by forming a coating pressure-sensitive adhesive layer on the release liner and pasting the release liner together. In addition, the substrate is sufficiently adhered to the pressure-sensitive adhesive layer and does not easily peel off. On the other hand, the release liner can be easily peeled off from the pressure-sensitive adhesive layer, such as a release treatment. In the present invention, the adhesive tape, adhesive sheet and adhesive film are synonymous.

When applying the adhesive, the viscosity may be adjusted by adding a suitable liquid medium. For example, hydrocarbon-based solvents such as toluene, xylene, hexane and heptane; Ester solvents such as ethyl acetate and butyl acetate; Ketone solvents such as acetone and methyl ethyl ketone; Halogenated hydrocarbon-based solvents such as dichloromethane and chloroform; Ether-based solvents such as diethyl ether, methoxy toluene and dioxane; And other hydrocarbon-based solvents. However, water and alcohol may cause reaction inhibition between the acrylic copolymer (A) and the isocyanate curing agent (B-1), and thus need to be used with caution.

The coating method is not particularly limited, and a known method using a Meyer bar, spatula, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater and spin coater can be used. The drying method is not particularly limited, and examples include hot air drying, steam drying, infrared drying, and vacuum drying. Drying conditions are not particularly limited, and are generally good for heating with hot air or steam at about 60 to 180 ° C.

In the present invention, the substrate is not particularly limited, for example, plastic film; Various optical films, such as an anti-reflection (AR) film, a polarizing plate, and a retardation plate, are mentioned. Examples of the plastic film include polyvinyl chloride film, polyethylene film, polyethylene terephthalate (PET) film, polyurethane film, nylon film, polyolefin film, triacetyl cellulose film, and cycloolefin film. Although the thickness of the substrate is not particularly limited, 10 to 2000 µm is preferable.

The thickness of the pressure-sensitive adhesive layer is preferably 2 to 1000 μm, and more preferably 5 to 500 μm. Further, the pressure-sensitive adhesive layer may be either a single layer or a laminate of two or more layers.

The adherend (adhesive partner) of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but an acrylic plate having a transparent conductive film, a polycarbonate plate, a cycloolefin film, glass, and polyethylene terephthalate are preferable.

It is preferable to use the adhesive sheet of this invention for bonding of an optical member. When an optical member is a sheet shape, it is also called an optical film, Specifically, a polarizing film, a retardation film, an elliptical polarizing film, an anti-reflection film, a brightness improving film, etc. are mentioned.

In addition, since the pressure-sensitive adhesive sheet of the present invention can be used as a liquid crystal cell member or the like, it can be used for displays such as liquid crystal panels and plasma display panels (PDPs). In addition, the adhesive sheet of the present invention is more preferably used when manufacturing such a display as a touch panel. In particular, it is preferably used for bonding a resin plate base material such as a polycarbonate plate and a polymethyl methacrylate (PMMA) plate as a support for a touch panel, and an optical member such as an optical film. The outgas from the resin plate substrate can be suppressed, and even if left under a high temperature or high temperature and high humidity environment, no floating or peeling occurs, and high transparency can be maintained.

The adhesive of the present invention is suitable as an adhesive for an optical member as described above, other general label stickers, paints, high solid paints, elastic wall materials, coating film waterproofing materials, flooring materials, tackifiers, adhesives, laminating adhesives, laminated structure adhesives, sealants , Various molding materials, surface modification coatings, magnetic recording media, binders (ink binders, cast binders and fired brick binders, etc.), implant materials, microcapsules, glass fiber sizing, urethane foam (rigid, semi-rigid or soft), urethane RIM, UV · EB cured resin, thermosetting elastomer, microcellular, fiber processing, plasticizer, sound absorbing material, damping material, surfactant, gelling agent, resin for artificial marble, impact resistance imparting agent for artificial marble, resin film for ink (protection Film, etc.), resins for laminated glass, reactive diluents, elastic fibers, artificial leather, synthetic leather and other raw materials or additives. The.

[Example]

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "part" refers to "part by mass" and "%" refers to "mass%", respectively. In addition, the amount of components other than the solvent is a value in terms of non-volatile matter.

<Synthesis Example 1>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction vessel, half of the total amount of each monomer in Table 1 (50 parts) out of 100 parts, 0.2 parts of azobis isobutyronitrile as an initiator and 60 parts of ethyl acetate as a solvent, and the total amount of the remaining monomers, 60 parts of ethyl acetate and 60 parts of azobis isobuty The solution in which 0.2 parts of nitrile was mixed was added dropwise to the dropping tube over about 2 hours, and polymerized at 80 ° C for 6 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled and diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content of 30% and a viscosity of 4000 mPa · s. The acrylic copolymer obtained here was referred to as (A-1). In addition, Table 1 shows the weight average molecular weight (Mw) and molecular weight dispersion degree (Mw / Mn) of the obtained acrylic copolymer.

In addition, each symbol is as follows.

MA: methyl acrylate,

EA: ethyl acrylate

PMA: isopropyl methacrylate,

2-HEA: 2-hydroxy ethyl acrylate,

4-HBA: 4-hydroxy butyl acrylate

BA: butyl acrylate,

2EHA: 2-ethyl hexyl acrylate.

<Synthesis examples 2, 5 to 10>

Acrylic copolymers (A-2 and A-510) were synthesized in the same manner as in Synthesis Example 1, except that the composition was changed to Table 1. Table 1 shows the weight average molecular weight and molecular weight dispersion of the obtained acrylic copolymer.

<Synthesis Example 3>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction vessel, half of the total amount of each monomer in Table 1 (50 parts) out of 100 parts, 0.2 parts of azobis isobutyronitrile as an initiator and 60 parts of ethyl acetate as a solvent, the total amount of the remaining monomers, 60 parts of ethyl acetate, and azobis iso A solution in which 0.2 parts of butyronitrile was mixed was added dropwise to the dropping tube over about 2 hours. One hour after the completion of the dropwise addition, a mixed solution of 20 parts of methyl ethyl ketone, 1 part of α-pinene and 0.5 part of 2,2'-azobis (4-methoxy-2,4-dimethyl valeronitrile) over about 1 hour Dropping was carried out and polymerization was performed at 80 ° C for 6 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer solution having a nonvolatile content of 30% and a viscosity of 4000 mPa · s. Let the acrylic copolymer obtained here be (A-3). Table 1 shows the weight average molecular weight and molecular weight dispersion of the obtained acrylic copolymer.

<Synthesis Example 4>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction tank, half of the total amount of each monomer in Table 1 (50 parts) out of 100 parts, 0.2 parts of azobis isobutyronitrile as an initiator and 60% of ethyl acetate as a solvent, and the total amount of the remaining monomers, 60 parts of ethyl acetate and azobis The solution which mixed 0.2 parts of isobutyronitrile was dripped over the dropping tube over about 2 hours. One hour after completion of the dropwise addition, a mixture of 20 parts of methyl ethyl ketone and 1 part of α-pinene was added dropwise over about 1 hour and polymerized at 80 ° C for 6 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer solution having a nonvolatile content of 30% and a viscosity of 4000 mPa · s. Let the acrylic copolymer obtained here be (A-4).

<Synthesis Example 11>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction vessel, half of the total amount of each monomer in Table 1 (50 parts) out of 100 parts, 0.2 parts of azobis isobutyronitrile as an initiator and 60 parts of ethyl acetate as a solvent, the total amount of the remaining monomers, 60 parts of ethyl acetate, and azobis iso A solution in which 0.2 parts of butyronitrile was mixed was added dropwise to the dropping tube over about 2 hours. One hour after completion of the dropwise addition, a mixture of 25 parts of methyl ethyl ketone, 1 part of α-pinene and 0.5 part of 2,2'-azobis (4-methoxy-2,4-dimethyl valeronitrile) over about 1 hour Dropping was carried out and polymerization was carried out at 80 ° C for 10 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled and diluted with ethyl acetate to obtain a copolymer solution having a nonvolatile content of 30% and a viscosity of 4000 mPa · s. Let the acrylic copolymer obtained here be (A-11).

<Comparative Synthesis Example 1>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction vessel, 0.05 parts of azobis isobutyronitrile as an initiator and 100 parts of ethyl acetate as a solvent were added, and a mixed solution of 30 parts of 2-hydroxy ethyl acrylate and 70 parts of butyl acrylate was added dropwise over a period of about 2 hours at a reflux temperature. did. During the polymerization 30 minutes after the start of dropping, a solution in which 0.05 part of azobis isobutyronitrile was dissolved in 10 parts of ethyl acetate was added. Polymerization was carried out in a nitrogen atmosphere for 3.5 hours. After the reaction was completed, the mixture was cooled and diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content of 35% and a viscosity of 5500 mPa · s.

<Comparative Synthesis Example 2>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction vessel, add half of the mixture consisting of 60 parts of butyl acrylate, 20 parts of methyl methacrylate, 20 parts of 2-hydroxy ethyl acrylate, 100 parts of ethyl acetate and 1 part of azobis isobutyronitrile as an initiator, and The whole amount was dripped over a dropping tube over about 2 hours and polymerized at 80 ° C for 6 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled and diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content of 35% and a viscosity of 5000 mPa · s.

<Comparative Synthesis Example 3>

A reaction apparatus equipped with a reaction tank, agitator, reflux cooling tube, nitrogen introduction tube, thermometer, and dripping tube was used. In the reaction tank, half of the mixture consisting of 60 parts of butyl acrylate, 20 parts of methyl acrylate, 20 parts of 2-hydroxy ethyl acrylate, 0.8 parts of azobis isobutyronitrile as an initiator, and 100 parts of ethyl acetate as a solvent was added, and the rest The whole amount of the mixture was dropped into the dropping tube over about 2 hours and polymerized at 80 ° C for 5 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled and diluted with ethyl acetate to obtain an acrylic copolymer solution having a nonvolatile content of 40% and a viscosity of 4000 mPa · s.

<Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)>

The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC). As the equipment, GPC equipment manufactured by Shimadzu Corporation, LC-GPC system "Prominence" was used. In addition, as a column, what was manufactured by Tosoh Corp .: TSKgel α-M in two in series was used. It measured at 40 degreeC using tetrahydrofuran (THF) as an eluent. Mn and Mw were determined by conversion values using polystyrene in which Mn and Mw are known as standard materials. Moreover, the molecular weight dispersion which divided Mw by Mn also calculated | required Mw / Mn.

In the examples, the following materials were used.

<Curing agent (B)>

HMDI-B: ("NP-1200", manufactured by Mitsui Chemicals, burette of hexa methylene diisocyanate)

HMDI-N: ("D-172N", manufactured by Mitsui Chemicals, a hydrate of hexamethylene diisocyanate)

HMDI-TMP: ("D-160N", manufactured by Mitsui Chemicals, trimethylol propane modified product of hexamethylene diisocyanate)

TDI-TMP: ("Coronate L", manufactured by Tosoh Corporation, trimethylol propane-modified triylene isocyanate)

TDI-TMP-2HD: (Reaction product of trimethylol propane-modified trilene isocyanate and 2-hexyl decanol, see preparation example 1 below)

Zirconium tetra acetyl acetonate: ("Organics ZC-700", manufactured by Matsumoto Fine Chemical Co., Ltd.)

Aluminum triacetyl acetonate: ("M-5A", Sokenkagaku company make).

<Production Example 1> TDI-TMP-2HD production

In a four-necked flask equipped with a stirrer, reflux cooling tube, nitrogen introduction tube, thermometer, and dropping funnel, 100 parts of TDI-TMP adduct (`` Des Module L75 '', manufactured by Sumika Covestro Urethane), 16.7 parts of 2-hexyl decanol And 116.7 parts of ethyl acetate as a diluting solvent, reacted at 60 ° C. for 5 hours to obtain TDI-TMP-2HD of 50% nonvolatile matter.

<Silane coupling agent (C)>

KBM-303: (3- (3,4-epoxy cyclohexyl) ethyl trimethoxy silane, manufactured by Shin-Etsu Chemical Co., Ltd.)

KBM-403: (3-glycidoxy propyl trimethoxy silane, manufactured by Shin-Etsu Chemical Co., Ltd.).

<Example 1>

0.2 parts of TDI-TMP-2HD and 0.1 parts of KBM-303 were blended with 100 parts of the acrylic copolymer obtained in Synthesis Example 1 to obtain an adhesive. The obtained pressure-sensitive adhesive was coated on a first peelable sheet using a comma coater on a peeling liner having a thickness of 38 µm (SP-PET38: manufactured by Mitsui Chemical Co., Ltd.) so that the thickness after drying was 100 µm, and at 120 ° C. Dry for 3 minutes. Moreover, a peeling lie (trade name P-2010: manufactured by Lintec Co., Ltd.) having a thickness of 75 µm was attached to the adhesive layer as a second peelable sheet, and aged at 23 ° C for 7 days in this state to obtain an adhesive sheet.

<Examples 2 to 23 and Comparative Examples 1 to 3>

As shown in the above, an adhesive and an adhesive sheet were obtained in the same manner as in Example 1, except that the type and blending amount of the acrylic copolymer, curing agent, and silane coupling agent were changed. In Table 2, unless otherwise stated, numerical values indicate parts and contain no blanks.

The adhesive strength, the moist heat whitening resistance, the outgas resistance, and the bending resistance were evaluated. Table 2 shows the results.

<Adhesive force>

The first release liner was peeled off from the obtained adhesive sheet, and the exposed adhesive layer was attached to a PET film (A-4300 manufactured by TOYOBO Co., 188 µm thick), cut to a size of 25 mm wide by 100 mm long, and tested. An adhesive sheet was produced. The second release liner was removed from this test adhesive sheet, and in an atmosphere of 23 ° C.-50% RH, the exposed pressure-sensitive adhesive layer was applied to a PET film having a thickness of 50 μm (Lumira T-60: manufactured by Toray Industries), and again JIS Z Roll compression was performed according to -0237. Peel strength (peeling angle 180 °, peeling speed 300 mm / min; unit N / 25 mm width) was measured on a tensile tester (Tensiron: manufactured by Orientech) after 24 hours after compression. The evaluation criteria are as follows.

◎: Peeling strength is 15N / 25mm or more. rainfall.

○: Peel strength is 10N / 25mm or more and less than 15N / 25mm. Good.

△: Peeling strength is 5N / 25mm or more but less than 10N / 25mm. Practical.

X: Peeling strength is less than 5N / 25mm. Not practical.

<My moist heat whitening>

The first release liner was peeled off from the obtained adhesive sheet, and the exposed adhesive layer was cut to a PET film (A-4300 manufactured by Toyo Spinning Co., 188 μm thick) to a size of 25 mm wide x 80 mm long, and the test pressure sensitive adhesive sheet was cut. Produced. Next, the second release liner was peeled off from the test adhesive sheet in an atmosphere of 23 ° C.-50% RH, and the exposed pressure-sensitive adhesive layer was overlaid on a glass plate (30 mm wide x 100 mm long) to adhere using a laminator. This was left under an environment of 85 ° C-85% RH for 500 hours, cooled at 23 ° C-50% RH for 6 hours, and then HAZE was measured. In addition, HAZE was measured using the Nippon Denshoku Kogyo Co., Ltd. TurbidimeterNDH5000W. The evaluation criteria are as follows.

◎: HAZE is less than 1.5. rainfall.

○: HAZE is 1.5 or more but less than 3.0. Good.

△: HAZE is 3.0 or more but less than 6.0. Practical.

×: HAZE is 6.0 or higher. Not practical.

<My out gas castle>

Peel off the first release liner from the obtained adhesive sheet, attach the exposed adhesive layer to a PET film (Toyobo Co., Ltd. A-4300, thickness 188 µm), cut to a size of 40 mm width x 50 mm length, and test adhesive sheet Produced. Next, the second release liner was peeled off from the test pressure-sensitive adhesive sheet, and the exposed pressure-sensitive adhesive layer was bonded to a polycarbonate (PC) plate (trade name: Upyron NF2000: Mitsubishi Gas Co., Ltd.) having a thickness of 0.5 mm. It was maintained under a pressure of 0.5 MPa in an atmosphere of 50 ° C. for 20 minutes to prepare a specimen laminated in the order of PET film / adhesive layer / PC plate. The test piece was left in an oven at 80 ° C for 24 hours. After standing for 24 hours in an atmosphere of 23 ° C. again, the state of the interface between the pressure-sensitive adhesive layer and the PC plate was visually observed and evaluated according to the following criteria.

◎: There is no change in the state of the interface and the adhesive layer. rainfall.

(Circle): There is some floating of a bubble or an adhesive layer at an interface (1 or more and less than 5 in the case of a bubble, and the floating area is less than 5% of the whole in case of a lift). Good.

(Triangle | delta): There is some floating of a bubble or an adhesive layer in an interface (5 or more and less than 20 in the case of a bubble, and the floating area is 5% or more and less than 10% of the whole when it is lifted). Practical.

X: There is a lot of air bubbles or adhesive layer excitation at the interface (20 or more bubbles, and 10% or more of the floating area when floating). Not practical.

<Bending resistance>

After peeling the first release liner from the pressure-sensitive adhesive sheet obtained under an atmosphere of 23 ° C.-50% RH, attaching the exposed pressure-sensitive adhesive layer to a PET film (Toyobo Co., Ltd. A-4300, thickness 188 μm), and then The release liner was peeled off, and the exposed adhesive layer was laminated on a polarizing plate (triacetyl cellulose film / polyvinyl alcohol film / polymethyl methacrylate film). Subsequently, the laminated body was put into an autoclave, and the pressure of 0.5 MPa was maintained for 20 minutes in an atmosphere of 50 ° C. Next, the laminate was taken out, left at 23 ° C.-50% RH for 30 minutes, and cut to a size of 25 mm in width * 100 mm in length to prepare a measurement sample. The obtained sample was subjected to a bending test 100,000 times in an environment of 25 ° C using a repeated bending tester (a small-sized tabletop durability tester: manufactured by Yuasa Systems Equipment Co., Ltd.) to evaluate the lifting and peeling state of the bent portion. The evaluation criteria are as follows.

◎: No lifting or peeling. rainfall.

○: Lifting and peeling less than 2 mm. Good.

△: Lifting and peeling 2 mm or more and less than 3 mm. Practical.

×: Excitation and peeling: 3 mm or more. Not practical.

<Housework time>

The viscosity of the pressure-sensitive adhesive immediately after mixing the curing agent in an atmosphere of 25 ° C. was measured using a B-type viscometer (rotor: No. 3, number of revolutions: 12 rpm, measurement time: 1 minute unit: mPa · s). After leaving this adhesive in a 25 degreeC atmosphere for 12 hours, the viscosity was measured like the above. The viscosity change rate before and after leaving the adhesive was calculated. The evaluation criteria are as follows.

○: Viscosity change is less than 30%. Good.

△: viscosity change of 30% or more and less than 100%. Practical.

X: Viscosity change of 100% or more. Not practical.

As shown in Table 2, all of the comparative examples could not satisfy one or more items of adhesion, moist heat whitening resistance, outgas resistance, bending resistance, and pot life. On the other hand, in all of the examples, good results were obtained for all items of adhesion, moist heat whitening resistance, outgas resistance, bending resistance, and pot life.

The pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention exhibit excellent effects on adhesive strength, moisture-heat whitening resistance, gas-out resistance, bending resistance, and pot life, and are suitable for use in adhesive applications of optical members fixed to displays and touch panels. Appeared to be.

[Table 1]

[Table 2]

Claims (7)

At least, 30 to 60 parts by mass of the (meth) acrylic acid alkyl ester (a1) having 1 to 3 carbon atoms in the alkyl group, 15 to 60 parts by mass of the (meth) acrylic acid ester (a2) containing a hydroxyl group, and 4 to 8 carbon atoms in the alkyl group (Meta) Acrylic acid alkyl ester (a3) An acrylic copolymer (A) of a mixture containing 10 to 50 parts by mass of a mixture, a curing agent (B), and an adhesive that satisfies the following requirements:
The mixture comprises two or more (a2),
The total amount of (a1), (a2) and (a3) is 100 parts by mass,
The total amount (parts by mass) of (a1) and (a2) ≥ (a3) is the amount (parts by mass).
According to claim 1,
The pressure-sensitive adhesive having a molecular weight dispersion of 5.5 to 15 of the acrylic copolymer (A).
The method according to claim 1 or 2,
A pressure-sensitive adhesive, wherein the curing agent (B) comprises an isocyanate curing agent (B-1).
According to claim 3,
The isocyanate curing agent (B-1) is a reaction product of an isocyanate compound having three or more isocyanato groups and alcohol, and includes an isocyanate curing agent having two or more isocyanato groups,
The amount of the isocyanate curing agent (B-1) to be blended is 0.01 to 0.4 mass parts with respect to 100 parts by mass of the acrylic copolymer (A), the pressure-sensitive adhesive.
The method according to claim 1 or 2,
The curing agent (B) includes a metal chelate curing agent (B-2),
The amount of the metal chelate curing agent (B-2) is 0.1 to 5 mass densities, and the pressure-sensitive adhesive is based on 100 parts by mass of the acrylic copolymer (A).
The adhesive sheet which has a base material and an adhesive layer which is a hardened | cured material of the adhesive of Claim 1 or 2.
The adhesive sheet which has a peelable sheet and the adhesive layer which is hardened | cured material of the adhesive of Claim 1 or 2.