KR20180114505A - Adhesive composition, and adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive sheet, which is not in the form of citron peel, is excellent in weatherability, foam resistance, and reworkability, and does not cause zipping; and provides an adhesive composition capable of obtaining the adhesive sheet. According to the present invention, the adhesive composition comprises: a (meth) acrylic copolymer (A), which is a copolymer of a monomer component, comprising (meth) acrylic acid alkyl ester having the Tg of a homopolymer of 0°C or higher, (meth) acrylic acid alkyl ester having the Tg of a homopolymer of less than 0°C, and carboxyl group-containing monomer; (meth) acrylic copolymer (B), which is a copolymer of a monomer component, comprising methacrylic acid alkyl ester and an amino group-containing monomer; and a cross-linking agent (C). The amount of a polymerization initiator contained in 100 wt% of the solid content of the adhesive composition is 800 ppm or less.

Description

[0001] ADHESIVE COMPOSITION AND ADHESIVE SHEET [0002]

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet.

Conventionally, a transparent plastic such as a polycarbonate (PC) or polymethylmethacrylate (PMMA) has been attached to an adhesive film for protection and scattering prevention. In order to protect the glass and prevent scattering of the glass, an adhesive film is also stuck.

In a display of an image display apparatus such as a liquid crystal display apparatus, a front plate such as a plastic plate or a glass plate is usually provided on the uppermost side for the purpose of protecting internal components. There is a case where a sticking sheet for scattering prevention is attached to the front plate for preventing scattering of plastic or glass when an impact is applied and broken.

The adhesive sheet for scattering prevention generally has a polyethylene terephthalate (PET) film and a pressure-sensitive adhesive layer provided on the PET film.

The pressure-sensitive adhesive used in such a pressure-sensitive adhesive layer is required to have weatherability, transparency, ease of control of adhesion, and the like. In addition, the generation of foaming and swelling largely affects the appearance of the pressure-sensitive adhesive sheet, and therefore the property of preventing these occurrence, that is, the foamability is also required.

In order to satisfy these requirements, a pressure-sensitive adhesive having weatherability, transparency, ease of control of adhesion, and foam resistance has been proposed (see, for example, Patent Document 1).

Patent Document 1 discloses a resin composition comprising a resin composition (1) having a weight average molecular weight of 800,000 or more obtained by copolymerizing a (meth) acrylic acid alkyl ester and a copolymerizable unsaturated monomer containing a carboxyl group, and a methacrylic acid alkyl ester or methacrylic acid cycloalkyl ester, There is proposed a pressure-sensitive adhesive composition containing a resin composition (2) having a weight-average molecular weight of 100,000 or less, obtained by copolymerizing one or more monomers selected from benzyl acrylate and styrene with a copolymerizable unsaturated monomer containing an amino group . Patent Document 1 discloses that a combination of a main polymer having a carboxyl group and a low molecular polymer having an amino group improves foam resistance by interaction between a carboxyl group and an amino group and has problems in properties such as weatherability, transparency, .

Japanese Patent No. 3516035

In recent years, the pressure-sensitive adhesive sheet used for scattering-preventing uses has been required to have further improved properties in terms of weather resistance, transparency, ease of control of adhesive force, and foam resistance, as well as excellent reworkability and no jamming phenomenon .

Further, when a pressure-sensitive adhesive sheet is produced and used using a conventional pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer sometimes has a so-called citron peel shape. Since the appearance of the pressure-sensitive adhesive sheet in the form of a citron peel is significantly lowered, improvement has been required.

It is an object of the present invention to provide a pressure-sensitive adhesive sheet which is not in the form of a citrus peel, is excellent in weather resistance, foam resistance and reworkability and does not cause a phenomenon of jitter, and is intended to provide a pressure-sensitive adhesive composition capable of obtaining the pressure- .

As a result of intensive investigations to solve the above problems, the inventors of the present invention found that the polymerization initiator remaining in the pressure-sensitive adhesive composition causes a reaction due to factors such as keeping the pressure-sensitive adhesive sheet in a high temperature environment or UV irradiation, Which is the main cause of the phenomenon. Therefore, when a pressure-sensitive adhesive composition having excellent weather resistance, i.e., UV resistance, is used, the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is not in the form of a citron peel can be obtained. In order to prevent the pressure- Thereby completing the present invention.

That is, the present invention relates to, for example, the following [1] to [3].

(1) a homopolymer having a glass transition temperature (Tg) of 0 ° C or higher, and further containing 13 to 35 mass% of a (meth) acrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms and a glass transition temperature (Meth) acrylic-based copolymer which is a copolymer of a monomer component containing less than 0 占 폚, more preferably 55 to 80 mass% of a (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms in the alkyl group and 3.5 to 10 mass% (B) which is a copolymer of a monomer component containing an amino group-containing monomer and a methacrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms and a cross-linking agent (C) Wherein the pressure-sensitive adhesive composition comprises 1 to 40 parts by mass of a (meth) acrylic copolymer (B) and 0.01 to 5 parts by mass of a crosslinking agent (C) relative to 100 parts by mass of the (meth) acrylic copolymer , The amount of the polymerization initiator contained in 100% by weight of the solid content of the pressure-sensitive adhesive composition Or less.

[2] The pressure-sensitive adhesive composition according to the above-mentioned [1], wherein the (meth) acrylic copolymer (B) has a weight average molecular weight of 1,000 to 50,000 and a glass transition temperature of 80 ° C or more.

[3] A pressure-sensitive adhesive sheet produced from the pressure-sensitive adhesive composition according to [1] or [2] above.

INDUSTRIAL APPLICABILITY The present invention provides a pressure-sensitive adhesive sheet which does not form a citron peel, is excellent in weatherability, foam resistance and reworkability, does not cause a zipping phenomenon, and a pressure-sensitive adhesive composition capable of obtaining the pressure-sensitive adhesive sheet.

Hereinafter, the present invention will be described in detail.

In the present invention, " (meth) acrylic " is used generically to mean acryl and methacryl. That is, the term "(meth) acrylic acid alkyl ester" is used generically to mean alkyl acrylate ester and methacrylic acid alkyl ester. The term " (meth) acrylate " is used generically to mean acrylate and methacrylate.

[Pressure sensitive adhesive composition]

The pressure-sensitive adhesive composition of the present invention is characterized in that the homopolymer has a glass transition temperature (Tg) of 0 ° C or higher, 13 to 35 mass% of a (meth) acrylic acid alkyl ester having 1 to 12 carbon atoms in an alkyl group, (Meth) acrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms in an amount of 55 to 80 mass%, and a carboxyl group-containing monomer in an amount of 3.5 to 10 mass% (Meth) acrylic copolymer (B) which is a copolymer of a monomer component containing an amino group-containing monomer and a methacrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms and a crosslinking agent (C) Wherein the pressure-sensitive adhesive composition comprises 1 to 40 parts by mass of the (meth) acrylic copolymer (B), 0.01 to 5 parts by mass of the crosslinking agent (C) per 100 parts by mass of the (meth) acrylic copolymer , And the pressure-sensitive adhesive composition, The amount of the polymerization initiator is also not more than 800ppm.

The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention is preferable because it does not form a citron peel, and is excellent in weatherability, foam resistance and reworkability and does not cause a zipping phenomenon.

((Meth) acrylic copolymer (A))

The pressure-sensitive adhesive composition of the present invention contains the (meth) acrylic copolymer (A). (Meth) acrylic copolymer (A-1) having a glass transition temperature (Tg) of 0 占 폚 or more of the homopolymer and a number of carbon atoms in the alkyl group of 1 to 12 in an amount of 13 to 35 mass 55 to 80% by mass of a (meth) acrylic acid alkyl ester (a-2) having a glass transition temperature (Tg) of the homopolymer of less than 0 ° C and an alkyl group having 1 to 12 carbon atoms, and a carboxyl group- a-3) in an amount of 3.5 to 10% by mass.

((Meth) acrylic acid alkyl ester (a-1))

(Meth) acrylic acid alkyl ester (a-1) is a (meth) acrylic acid alkyl ester having a homopolymer having a glass transition temperature (Tg) of 0 ° C or higher and an alkyl group having 1 to 12 carbon atoms.

As the (meth) acrylic acid alkyl ester (a-1), the glass transition temperature (Tg) of the homopolymer is preferably 0 to 120 ° C, more preferably 0 to 100 ° C. When the Tg is within the above range, the durability of the obtained pressure-sensitive adhesive layer can be enhanced.

As the (meth) acrylic acid alkyl ester (a-1), the number of carbon atoms of the alkyl group is preferably from 1 to 8, more preferably from 1 to 4. The alkyl group may be a linear alkyl group or an alkyl group having a branch.

Specific examples of the (meth) acrylic acid alkyl ester (a-1) include methyl acrylate (Tg: 8 캜), n-propyl acrylate (Tg: 3 캜), t- (Tg: 22 占 폚), methyl methacrylate (Tg: 105 占 폚), ethyl methacrylate (Tg: 65 占 폚), n-propyl methacrylate (Tg: 35 占 폚), isopropyl methacrylate : 81 ° C), n-butyl methacrylate (Tg: 20 ° C), isobutyl methacrylate (Tg: 48 ° C), and t-butyl methacrylate (Tg: 118 ° C).

As the (meth) acrylic acid alkyl ester (a-1), one type may be used alone, or two or more types may be used. Examples of the (meth) acrylic acid alkyl ester (a-1) include methyl acrylate, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, Methyl acrylate and t-butyl acrylate are more preferable, and methyl acrylate is particularly preferable.

In the present invention, the glass transition temperature (Tg) of the homopolymer of each monomer may be, for example, a value described in Polymer Handbook Forth Edition (Wiley-Interscience 2003).

((Meth) acrylic acid alkyl ester (a-2))

(Meth) acrylic acid alkyl ester (a-2) is a (meth) acrylic acid alkyl ester having a homopolymer having a glass transition temperature (Tg) of less than 0 占 폚 and an alkyl group having 1 to 12 carbon atoms.

As the (meth) acrylic acid alkyl ester (a-2), the glass transition temperature (Tg) of the homopolymer is preferably -80 to -10 ° C, more preferably -65 to -10 ° C. When the Tg is within the above range, the pressure-sensitive adhesive layer to be obtained is preferable in that it has appropriate stress relaxation properties.

As the (meth) acrylic acid alkyl ester (a-2), the number of carbon atoms in the alkyl group is preferably from 2 to 12, more preferably from 4 to 10. The alkyl group may be a linear alkyl group or an alkyl group having a branch.

(Tg: -24 占 폚), isopropylacrylate (Tg: -3 占 폚), n-butyl acrylate (Tg: -50 占 폚), and the like. Specific examples of the (meth) acrylic acid alkyl ester (a- (Tg: -65 占 폚), isooctyl acrylate (Tg: -40 占 폚), n-hexyl acrylate (Tg: -5 ° C), 2-ethylhexyl acrylate (Tg: -70 ° C), nonyl acrylate (Tg: -58 ° C), lauryl acrylate (Tg: -3 ° C), n-pentyl methacrylate ), n-hexyl methacrylate (Tg: -5 DEG C), n-octyl methacrylate (Tg: -20 DEG C), isooctyl methacrylate (Tg: (Tg: -10 占 폚), isodecyl methacrylate (Tg: -41 占 폚), and lauryl methacrylate (Tg: -65 占 폚).

As the (meth) acrylic acid alkyl ester (a-2), one type may be used alone, or two or more types may be used. Examples of the (meth) acrylic acid alkyl ester (a-2) include ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, Isooctyl methacrylate, isooctyl methacrylate, isooctyl methacrylate and lauryl methacrylate is preferable, and at least one monomer selected from n-butylacrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isodecyl methacrylate, Methacrylate is more preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable.

(Carboxyl group-containing monomer (a-3))

The carboxyl group-containing monomer (a-3) is a monomer having a carboxyl group in the molecule.

It is possible to interact with the amino group of the (meth) acrylic copolymer (B) described later by using the carboxyl group-containing monomer (a-3) as the monomer component used for obtaining the (meth) acrylic copolymer And a pressure-sensitive adhesive sheet having excellent aging properties can be obtained.

Specific examples of the carboxyl group-containing monomer (a-3) include acrylic acid, methacrylic acid,? -Carboxyethyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, succinic acid mono (meth) acryloyloxyethyl ester , ω-carboxypolycaprolactone mono (meth) acrylate, crotonic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid.

The carboxyl group-containing monomers (a-3) may be used singly or in combination of two or more.

As the carboxyl group-containing monomer (a-3), at least one monomer selected from acrylic acid, methacrylic acid and? -Carboxyethyl (meth) acrylate is preferably used, and at least one monomer selected from acrylic acid and methacrylic acid It is more preferable to use a monomer of the species. These monomers are preferable because they are industrially available.

(Monomer component of the (meth) acrylic copolymer (A)

As described above, the (meth) acrylic copolymer (A) contains 13 to 35 mass% of the (meth) acrylic acid alkyl ester (a-1) and 55 to 80 mass% of the (meth) acrylic acid alkyl ester (a- , And 3.5 to 10 mass% of a carboxyl group-containing monomer (a-3). However, the total amount of the monomer components is 100% by mass.

The monomer component may contain (a-1) to (a-3) within the above range, and may contain monomers other than (a-1) to (a-3). (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-methoxyethyl (meth) acrylate, Alkoxyalkyl (meth) acrylates such as ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate and 4-ethoxybutyl (meth) acrylate; 2-hydroxyethyl (Meth) acrylate such as 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 8- ) Acrylate: (meth) acrylate containing a cyclic alkyl group such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate: benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (Meth) acrylate containing an aromatic ring such as acrylate . As the monomer component, it is preferable not to include an amino group-containing monomer described later.

the monomers other than (a-1) to (a-3) are usually used in an amount of not more than 20% by mass , Preferably not more than 10 mass%.

(Meth) acrylic acid alkyl ester (a-2) and the carboxyl group-containing monomer (a-3) in an amount of 13 to 35 mass%, (meth) acrylic acid alkyl ester (Meth) acrylic acid alkyl ester (a-2) in an amount of from 15 to 30 mass%, (meth) acrylic acid alkyl ester (a-2) in an amount of from 60 to 78 mass%, and a carboxyl group-containing monomer (a-3) in an amount of 4 to 10 mass%.

(Production conditions of the (meth) acrylic copolymer (A)

The (meth) acrylic copolymer (A) used in the present invention is obtained by copolymerizing the above monomer components.

The copolymerization can be carried out, for example, by a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method and a suspension polymerization method, and among these, a solution polymerization method is preferable.

Specifically, a polymerization initiator is added in an inert gas atmosphere such as a nitrogen gas by introducing a polymerization solvent and a monomer component into a reaction vessel, and the reaction initiation temperature is usually set at 40 to 100 ° C, preferably 50 to 90 ° C, (Meth) acrylic copolymer (A) can be obtained by maintaining the reaction system at a temperature of usually 50 to 90 ° C, preferably 60 to 90 ° C, for 3 to 20 hours.

Examples of the polymerization initiator include azo-based initiators and peroxide-based polymerization initiators.

Examples of the azo initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'- Azobis (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile) , 1'-azobis (cyclohexane-1-carbonitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile , 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) (2-hydroxyethyl) -propionamide], 2,2'-azobis (isobutylamido) dihydrate, 4,4'-azobis (4-cyanopentanoic acid) Azobis (2-cyanopropanol), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis (2- Butyl -N- (2- hydroxyethyl) propionamide), and the azo compounds such as.

Examples of the peroxide-based polymerization initiator include t-butyl hydroperoxide, cumene hydrooxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di- (4,4-di-t-butylperoxycyclohexyl) butane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2- ) ≪ / RTI >

The polymerization initiator may be used alone or in combination of two or more. In addition, the addition of the polymerization initiator plural times during the polymerization is not limited.

The polymerization initiator is used in an amount within a range of usually 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass based on 100 parts by mass of the monomer component forming the (meth) acrylic copolymer (A). In addition, a polymerization initiator, a chain transfer agent, a polymerizable monomer and a polymerization solvent may be appropriately added during the polymerization reaction.

As the polymerization solvent to be used for the solution polymerization, for example, aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane; Alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and cyclooctane; Ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenyl ethyl ether and diphenyl ether; Halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane and chlorobenzene; Esters such as ethyl acetate, propyl acetate, butyl acetate and methyl propionate; Ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; Amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; Nitrites such as acetonitrile and benzonitrile; Dimethyl sulfoxide, sulfoxides such as sulfolane, and the like.

The polymerization solvent may be used alone, or two or more types may be used.

(Physical Properties of (Meth) Acrylic Copolymer (A)

The (meth) acrylic copolymer (A) has a weight average molecular weight (Mw) measured by a gel permeation chromatography (GPC) method in terms of polystyrene, and is usually 400,000 or more, More preferably from 600,000 to 1.3 million, and even more preferably from 700,000 to 1.2 million. When the Mw is equal to or lower than the lower limit value, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is preferable in terms of excellent durability and cohesion. When the Mw is not more than the upper limit, it is preferable from the viewpoint of good coating property of the pressure-sensitive adhesive composition.

(Weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic copolymer (A) measured by the GPC method is usually 1.5 to 20, preferably 2 to 18, 2 to 15. When Mw / Mn is not lower than the lower limit described above, it is preferable from the viewpoint of exhibiting the adhesion property between the pressure-sensitive adhesive layer and the substrate in the pressure-sensitive adhesive sheet and the adhesion with the adherend of the pressure-sensitive adhesive sheet. When Mw / Mn is not more than the upper limit, it is preferable from the standpoint of excellent heat resistance and durability.

The glass transition temperature (Tg) of the (meth) acrylic copolymer (A) determined from the Fox equation is usually -70 to 0 占 폚, preferably -70 to -20 占 폚. In such a case, a pressure-sensitive adhesive having excellent adhesive strength can be obtained.

The amount of the polymerization initiator (amount of the residual initiator) measured by the method described in the following Examples (gas chromatograph mass spectrometry (GCMS)) is usually 800 ppm or less, preferably 100 ppm or less, based on 100% by weight of the (meth) acrylic copolymer Is not more than 750 ppm, more preferably not more than 700 ppm. Also, in the present invention, ppm means ppm based on weight, that is, parts per million weight (ppmw). The lower limit of the amount of the residual initiator is, for example, 50 ppm or more based on 100 wt% of the (meth) acrylic copolymer (A), although the lower limit is not particularly limited.

The amount of the polymerization initiator contained in the (meth) acrylic copolymer (A) can be increased or decreased, for example, by adjusting the production conditions of the (meth) acrylic copolymer (A). For example, there is a tendency to decrease by increasing the reaction time in producing the (meth) acrylic copolymer (A), increasing the reaction temperature, and using an appropriate amount of the initiator. Conversely, there is a tendency to increase by shortening the reaction time, lowering the reaction temperature, and using an excessive amount of the initiator.

By setting the amount of the residual initiator of the (meth) acrylic copolymer (A) within the above range, the amount of the residual initiator in the pressure-sensitive adhesive composition of the present invention can be made 800 ppm or less. According to the study by the present inventors, the amount of the residual initiator in the pressure-sensitive adhesive composition of 800 ppm or less can suppress the side reaction which has been caused in the past due to the fact that the pressure-sensitive adhesive sheet is stored under a high temperature environment or UV- I found that it can prevent the formation of citron peel. Therefore, by controlling the amount of the residual initiator in the pressure-sensitive adhesive composition, it is possible to obtain a pressure-sensitive adhesive sheet which is excellent in weather resistance, foam resistance and reworkability and does not cause a phenomenon of jigging.

((Meth) acrylic copolymer (B))

The pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic copolymer (B). The (meth) acrylic copolymer (B) is a copolymer of a monomer component comprising a methacrylic acid alkyl ester (b-1) having an alkyl group of 1 to 20 carbon atoms and an amino group-containing monomer (b-2).

(Methacrylic acid alkyl ester (b-1))

The methacrylic acid alkyl ester (b-1) is a methacrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group.

As the methacrylic acid alkyl ester (b-1), the alkyl group has preferably 1 to 18 carbon atoms, more preferably 1 to 12, and still more preferably 1 to 8 carbon atoms.

Examples of the methacrylic acid alkyl ester (b-1) include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, Octyl methacrylate, decyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate, undeca methacrylate, lauryl methacrylate, stearyl methacrylate and isostearyl methacrylate. These may be used alone or in combination of two or more.

Examples of the methacrylic acid alkyl ester (b-1) include methyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, Stearyl methacrylate are preferable, and at least one kind of monomer selected from methyl methacrylate, isobutyl methacrylate, t-butyl methacrylate and 2-ethylhexyl methacrylate is preferable. Is more preferable.

(Amino group-containing monomer (b-2))

The amino group-containing monomer (b-2) is a monomer having an amino group in the molecule. The amino group-containing monomer (b-2) may be a monomer having one amino group in one molecule or a monomer having two or more amino groups.

Examples of the amino group-containing monomer (b-2) include N, N-dialkylaminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate and N, N- Metha) acrylate.

The amino group-containing monomer (b-2) may be used singly or in combination of two or more kinds.

The (meth) acrylic copolymer (B) in which the amino group-containing monomer (b-2) is copolymerized is preferable because of its excellent compatibility with the (meth) acrylic copolymer (A).

(Monomer component of the (meth) acrylic copolymer (B)

As described above, the (meth) acrylic copolymer (B) is a copolymer of a monomer component comprising a methacrylic acid alkyl ester (b-1) and an amino group-containing monomer (b-2).

As the monomer component, the methacrylic acid alkyl ester (b-1) and the amino group-containing monomer (b-2) are preferably used in an amount of 80 to 98 mass% and 2 to 20 mass% Of the amino group-containing monomer (b-2) is 85 to 96 mass% and the amino group-containing monomer (b-2) is 4 to 10 mass%. However, the total amount of the monomer components is 100% by mass.

The monomer component may contain (b-1) and (b-2), and may contain monomers other than (b-1) and (b-2). Examples of the monomers other than the monomers (b-1) and (b-2) include monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, Acrylate, isopentyl acrylate, hexyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate (Meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxyethyl (Meth) acrylates such as methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (Meth) acrylate having a cyclic alkyl group such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and the like; (Meth) acrylate such as phenyl (meth) acrylate, phenyl (meth) acrylate and phenoxyethyl (meth) acrylate. It is preferable that the monomer component does not contain the above-mentioned carboxyl group-containing monomer.

the monomers other than (b-1) and (b-2) are usually used in an amount of not more than 15% by mass when the total amount of the monomer components is 100% , Preferably not more than 10 mass%.

(Production Conditions of (Meth) Acrylic Copolymer (B)

The (meth) acrylic copolymer (B) used in the present invention is obtained by copolymerizing the above monomer components.

The copolymerization can be carried out, for example, by a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method and a suspension polymerization method, and among these, a solution polymerization method is preferable.

Specifically, a polymerization initiator is added in an inert gas atmosphere such as a nitrogen gas by introducing a polymerization solvent and a monomer component into a reaction vessel, and the reaction initiation temperature is usually set at 40 to 100 ° C, preferably 50 to 90 ° C, (Meth) acrylic copolymer (B) can be obtained by maintaining the reaction system at a temperature of usually 50 to 90 ° C, preferably 60 to 90 ° C, and allowing the reaction to proceed for 4 to 20 hours.

As the polymerization initiator, those described in the section of ((Production conditions of (meth) acrylic copolymer (A)) may be suitably used. The polymerization initiator used for preparing the (meth) acrylic copolymer (A) may be the same as or different from the polymerization initiator used for producing the (meth) acrylic copolymer (B).

The polymerization initiator is used in an amount within a range of usually 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass based on 100 parts by mass of the monomer component forming the (meth) acrylic copolymer (B). In addition, a polymerization initiator, a chain transfer agent, a polymerizable monomer and a polymerization solvent may be appropriately added during the polymerization reaction.

As the polymerization solvent to be used for solution polymerization, those described in the section of ((Production conditions of (meth) acrylic copolymer (A)) can be suitably used. The polymerization solvent used for producing the (meth) acrylic copolymer (A) may be the same as or different from the polymerization solvent used for producing the (meth) acrylic copolymer (B).

(Physical properties of the (meth) acrylic copolymer (B)

The (meth) acrylic copolymer (B) has a weight average molecular weight (Mw) measured by a gel permeation chromatography method (GPC method) in terms of polystyrene, usually 1000 to 50000, preferably 2000 to 30000 And more preferably from 3,000 to 10,000. Within the above range, the compatibility with the (meth) acrylic copolymer (A) described above is preferable.

(Weight average molecular weight (Mw) / number average molecular weight (Mn)) of the (meth) acrylic copolymer (B) measured by the GPC method is usually 1.1 to 10, preferably 1.2 to 8, 1.2 to 7, and more preferably 1.3 to 6.5.

The glass transition temperature (Tg) of the (meth) acrylic copolymer (B) determined from the Fox equation is usually 80 ° C or higher, preferably 85 to 120 ° C, and more preferably 90 to 110 ° C. If such a solar cell is used, a pressure-sensitive adhesive excellent in durability can be obtained.

The amount of the polymerization initiator (amount of the residual initiator) measured by the method described in the following Examples (gas chromatograph mass spectrometry (GCMS)) is usually 200 ppm or less, preferably 200 ppm or less, relative to 100 wt% of the (meth) acrylic copolymer Is preferably 150 ppm or less, more preferably 100 ppm or less. The lower limit value is not particularly limited, but the lower limit value of the amount of the residual initiator is, for example, 10 ppm or more based on 100% by weight of the (meth) acrylic copolymer (B).

The amount of the polymerization initiator contained in the (meth) acrylic copolymer (B) can be increased or decreased, for example, by adjusting the production conditions of the (meth) acrylic copolymer (B). For example, there is a tendency to decrease by increasing the reaction time in producing the (meth) acrylic copolymer (B), increasing the reaction temperature, and using an appropriate amount of the initiator. Conversely, there is a tendency to increase by shortening the reaction time, lowering the reaction temperature, and using an excessive amount of the initiator.

By setting the amount of the residual initiator of the (meth) acrylic copolymer (B) within the above range, the amount of the residual initiator in the pressure-sensitive adhesive composition of the present invention can be made 800 ppm or less. According to the study by the present inventors, it has been found that when the amount of the residual initiator in the pressure-sensitive adhesive composition is 800 ppm or less, side reactions can be suppressed by factors such as the pressure-sensitive adhesive sheet being stored under a high temperature environment or being irradiated with UV, I can not stop being. Therefore, by controlling the amount of the residual initiator in the pressure-sensitive adhesive composition, it is possible to obtain a pressure-sensitive adhesive sheet which is excellent in weather resistance, foam resistance and reworkability and does not cause a phenomenon of jigging.

(Crosslinking agent (C))

The pressure-sensitive adhesive composition of the present invention contains a cross-linking agent (C).

The crosslinking agent (C) is not particularly limited, but an epoxy crosslinking agent, an isocyanate crosslinking agent, a metal chelate compound and the like can be used. The crosslinking agent may be used alone or in combination of two or more.

Examples of the epoxy-based crosslinking agent include (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- N, N ', N'-tetraglycidylaminophenylmethane, triglycidyl isocyanate, mN, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl Toluidine, N, N-diglycidyl aniline, pentaerythritol polyglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like.

Examples of the isocyanate crosslinking agent include tolylene diisocyanate, chlorophenylene diisocyanato, hexamethylene diisocyanato, tetramethylene diisocyanato, isophorone diisocyanate, xylylene Isocyanate monomers such as diisocyanate, diphenylmethane diisocyanate and hydrogenated diphenylmethane diisocyanate, and addition reaction with trimethylolpropane or the like to these isocyanate monomers Isocyanate compound, burette type isocyanate compound, isocyanate compound, and isocyanate compound, which are additionally reacted with an isocyanate monomer such as polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol, And prepolymer type isocyanates.

Examples of the metal chelate compound include compounds in which alkoxide, acetylacetone, and acetoacetic acid ethyl are added to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium . Specific examples include aluminum isopropylate, aluminum secondary butylate, aluminum ethyl acetoacetate diisopropylate, aluminum tris ethyl acetoacetate and aluminum tris acetylacetonate.

As the crosslinking agent, an epoxy crosslinking agent is preferable from the viewpoint of excellent heat resistance.

The pressure-sensitive adhesive composition of the present invention can form a three-dimensional crosslinked structure by reacting with a crosslinking agent, and can exhibit cohesive force with high adhesive force.

(Composition of pressure-sensitive adhesive composition)

The pressure-sensitive adhesive composition of the present invention contains 1 to 40 parts by mass of the (meth) acrylic copolymer (B) and 0.01 to 5 parts by mass of the crosslinking agent (C) per 100 parts by mass of the (meth) acrylic copolymer (Meth) acrylic copolymer (B) in an amount of 3 to 35 parts by mass and the crosslinking agent (C) in an amount of 0.03 to 3 parts by mass, and more preferably 5 to 30 parts by mass of a (meth) acrylic copolymer , And 0.05 to 2.5 parts by mass of a crosslinking agent (C). When the blending amount of each component is within the above range, it is preferable that the pressure-sensitive adhesive composition of the present invention is used because it can obtain a pressure-sensitive adhesive sheet which is excellent in reworkability and does not cause a zipping phenomenon.

The pressure-sensitive adhesive composition of the present invention may further contain various additives such as a tackifier resin, an antistatic agent, a silane coupling agent, an antioxidant, a UV absorber, a plasticizer, a fine particle and a pigment in a range not impairing the physical properties of the pressure- . When the pressure-sensitive adhesive composition of the present invention contains components other than the above (A) to (C), components other than (A) to (C) are usually used in an amount of 0.03 to 30% by mass in 100% by mass of solid content of the pressure- Preferably 0.05 to 25% by mass, and more preferably 0.08 to 20% by mass.

The pressure-sensitive adhesive composition of the present invention may contain, in addition to the above components, an organic solvent to the extent that the effect of the present invention is not impaired.

Examples of the organic solvent include a polymerization solvent described in the description of the production method of the (meth) acrylic copolymer (A). The pressure-sensitive adhesive composition of the present invention can be produced, for example, by mixing a polymer solution containing a (meth) acrylic copolymer (A) and a polymerization solvent, a polymer solution containing a (meth) acrylic copolymer (B) ). ≪ / RTI > In the pressure-sensitive adhesive composition of the present invention, the content of the organic solvent is usually from 0 to 90% by mass, and preferably from 10 to 80% by mass.

(Production method of pressure-sensitive adhesive composition)

The pressure-sensitive adhesive composition of the present invention is obtained by mixing each component (for example, the above-mentioned (A) to (C)) contained in the pressure-sensitive adhesive composition by a known method using a stirring device or the like.

That is, the pressure-sensitive adhesive composition of the present invention is obtained by collectively or sequentially mixing and stirring the respective components. The stirring time is not particularly limited, but it may be about 10 to 120 minutes at room temperature in terms of workability and productivity.

(Physical properties of pressure-sensitive adhesive composition)

In the pressure-sensitive adhesive composition of the present invention, the amount of the polymerization initiator (residual initiator amount) contained in the solid content of 100% by weight of the pressure-sensitive adhesive composition is 800 ppm or less. The amount of the residual initiator is the amount of the polymerization initiator contained in the pressure-sensitive adhesive composition, and is expressed as the amount when the solid content of the pressure-sensitive adhesive composition is 100% by weight. The polymerization initiator contained in the pressure-sensitive adhesive composition of the present invention is derived from a polymerization initiator used for polymerizing the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B) One polymerization initiator is included in the pressure-sensitive adhesive composition, and the amount thereof is the residual initiator amount. When the pressure-sensitive adhesive composition of the present invention contains a polymer other than the (meth) acrylic copolymer (A) and the (meth) acrylic copolymer (B), the (meth) acrylic copolymer (A) When the polymerization initiator used in producing the polymer other than the acrylic copolymer (B) remains in the pressure-sensitive adhesive composition, the amount of the remaining polymerization initiator is also included in the amount of the residual initiator of the pressure-sensitive adhesive composition.

The amount of the residual initiator may be determined by removing the organic solvent from the pressure-sensitive adhesive composition, obtaining a solid content, and measuring the amount of the polymerization initiator contained in the solid content by a gas chromatograph mass spectrometer (GCMS) The amount of residual initiator in each component constituting the pressure-sensitive adhesive composition is measured, and the amount of residual initiator in each component and the amount of each component (Ratio).

The pressure-sensitive adhesive composition of the present invention has a polymerization initiator content of 800 ppm or less, more preferably 700 ppm or less, and particularly preferably 650 ppm or less, in 100 wt% of the solid content of the pressure-sensitive adhesive composition. Within this range, it is preferable that the layer (pressure-sensitive adhesive layer) formed from the pressure-sensitive adhesive composition of the present invention is inhibited from becoming a citron peel-like shape when irradiated with ultraviolet rays. The lower limit of the amount of the residual initiator in the pressure-sensitive adhesive composition of the present invention is preferably as low as possible, and is not particularly limited, but usually 30 ppm or more.

[Pressure-sensitive adhesive layer]

The pressure-sensitive adhesive layer is produced from the pressure-sensitive adhesive composition described above. Specifically, the pressure-sensitive adhesive layer can be obtained by, for example, carrying out the crosslinking reaction in the pressure-sensitive adhesive composition described above, specifically by crosslinking the (meth) acrylic copolymer (A) with the crosslinking agent (C).

The conditions for forming the pressure-sensitive adhesive layer are as follows, for example. The pressure-sensitive adhesive composition of the present invention is applied onto the release surface of the base material or the release sheet and varies depending on the type of the solvent. Usually, the pressure-sensitive adhesive composition is preferably applied at a temperature of 50 to 150 캜, preferably 60 to 100 캜, , It is dried for 2 to 7 minutes to remove the solvent and form a coating film. The film thickness of the dried coating film is usually 5 to 125 탆, preferably 10 to 100 탆.

The pressure-sensitive adhesive layer is preferably formed under the following conditions. The pressure-sensitive adhesive composition of the present invention is applied onto the release treatment surface of the substrate or release sheet, and the release sheet is applied onto the coating film formed under the above conditions, and then is applied for usually 3 days or more, preferably 7 to 10 days, C, preferably 15 to 40 占 폚, usually 5 to 70% RH, preferably 5 to 50% RH. When the crosslinking is carried out under the above-mentioned aging conditions, it is possible to efficiently form a crosslinked body (network polymer).

As a method of applying the pressure-sensitive adhesive composition, it is possible to apply the pressure-sensitive adhesive composition by a known method such as spin coating, knife coating, roll coating, bar coating, blade coating, die coating, Can be used.

[Adhesive sheet]

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer made from the pressure-sensitive adhesive composition of the present invention.

The pressure-sensitive adhesive sheet of the present invention is not in the form of a citron peel, and is excellent in weatherability, foam resistance, reworkability, and does not cause a zipping phenomenon, and thus can be suitably used for applications requiring these properties.

The pressure-sensitive adhesive sheet of the present invention may be a pressure-sensitive adhesive sheet comprising only the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, or may be a pressure-sensitive adhesive sheet as a laminate having a base layer and a pressure-sensitive adhesive layer.

The thickness of the pressure-sensitive adhesive layer may be suitably set according to the use of the pressure-sensitive adhesive sheet, and is not particularly limited, but is usually 5 to 125 占 퐉, preferably 10 to 100 占 퐉.

When the pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet comprising only the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is applied on the exfoliated base material and, if necessary, And a pressure-sensitive adhesive layer is formed by disposing a substrate. The pressure-sensitive adhesive sheet comprising only the pressure-sensitive adhesive layer is stored and moved together with the exfoliated base material during storage and movement, but the exfoliated base material is peeled off at the time of use and is used as a pressure-sensitive adhesive sheet comprising only a pressure-sensitive adhesive layer.

In the case where the pressure-sensitive adhesive sheet of the present invention is a laminate having a base layer and a pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive composition is applied onto a base material and, if necessary, Sensitive adhesive layer. This pressure-sensitive adhesive layer is used as a pressure-sensitive adhesive sheet comprising a base layer and a pressure-sensitive adhesive layer, with the base material being peeled off at the time of use.

As another example, a pressure-sensitive adhesive sheet may be obtained by providing a pressure-sensitive adhesive layer on both sides of a base layer and arranging a base material subjected to release treatment on both sides thereof.

Examples of the substrate include, but are not limited to, plastic, glass, woven fabric, nonwoven fabric, and paper. The transparent plastic is preferably used as the transparent plastic. Examples of the transparent plastic include polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polypropylene (PP), acrylonitrile-butadiene- (ABS), polyamide (nylon), and the like.

The application of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but it can be used as a pressure-sensitive adhesive sheet for protection and scattering prevention of plastic and glass.

(Example)

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The physical properties of the copolymer obtained in the following Production Examples and the amount of the residual initiator of the pressure-sensitive adhesive composition were measured by the following methods.

(Mw, Mw / Mn)

The weight average molecular weight and molecular weight distribution of the copolymer obtained in the following Production Example were measured by the gel permeation chromatography method (GPC method) under the following conditions. (1) TSKgel HxL-H (Guard column) (2) TSKgel GMHxL (3) TSKgel GMHxL (4) Columns: TSKgel G2500HxL · Flow rate: 1.0 mL / min · Column temperature: 40 ° C · Sample concentration: 1.5% (w / v) (diluted with tetrahydrofuran) · Mobile phase solvent: tetrahydrofuran · Standard polystyrene conversion

(Amount of residual initiator of the copolymer and pressure-sensitive adhesive composition)

The amounts of the residual initiator contained in the copolymer obtained in the following Production Examples and the pressure-sensitive adhesive compositions obtained in the respective Examples and Comparative Examples were measured by a gas chromatograph mass spectrometer (GCMS method) under the following conditions. ·Pretreatment

The polymer solution or pressure-sensitive adhesive composition was taken, and the polymer solution or pressure-sensitive adhesive composition was dissolved in acetone. The n-hexane was added dropwise while mixing the sample dissolved in the acetone, mixed well and allowed to stand for one hour. Thereafter, the supernatant was recovered and filtrated, and the filtrate was used as a sample solution. With respect to the obtained sample liquid, the amount of residual initiator was measured using a gas chromatograph mass spectrometer (GCMS method). The measured values obtained are shown in Tables 1 and 2 in terms of solid content of 100% by mass. Measuring apparatus: Agilent: 6890N / 5973inert (manufactured by Agilent Technologies) Column: HP-5ms 30mx0.25mm, 0.25μm (made by Agilent Technologies) Oven: 100C for 15 minutes, MS (ion source: 230 ° C, MS quadrupole: 150 ° C) Detection method: SIM · Split: 30: 1

The temperature of the oven and the temperature of the injection port can be set according to the kind of the polymerization initiator (half-life temperature of the polymerization initiator), and the above conditions are suitable for the 2,2'-azobisisobutyronitrile used in the production example.

[Production Example A-1]

75 parts by mass of n-butyl acrylate (BA) as a polymerizable monomer, 18 parts by mass of methyl acrylate (MA) as a polymerizable monomer, and 20 parts by mass of methyl methacrylate (MA) were placed in a two liter 4-necked flask equipped with a stirrer, a thermometer, 7 parts by mass of acrylic acid (AA) was added, and 150 parts by mass of ethyl acetate as a solvent was added.

Subsequently, while stirring in a nitrogen gas atmosphere, 0.1 part by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, and the reaction was carried out at 70 ° C for 7 hours. After completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution having a solid content concentration of 20 mass% including the copolymer A-1.

The Mw of the copolymer A-1 was 800,000, the Mw / Mn was 3.1, and the residual initiator amount was 660 ppm.

[Production Example A-2]

except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 77.5 parts by mass and the amount of acrylic acid (AA) was changed from 7 parts by mass to 4.5 parts by mass, A polymer solution having a solid content concentration of 20 mass% including A-2 was prepared.

The Mw of the copolymer A-2 was 800,000, the Mw / Mn was 3.3, and the residual initiator amount was 670 ppm.

[Production Example A-3]

The procedure of Production Example A-1 was repeated except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 63 parts by mass and the amount of methyl acrylate (MA) was changed from 18 parts by mass to 30 parts by mass, To prepare a polymer solution having a solid content concentration of 20% by mass containing the copolymer A-3.

The Mw of the copolymer A-3 was 750,000, the Mw / Mn was 3.4, and the residual initiator amount was 680 ppm.

[Production Example A-4]

Except that the amount of the polymerization initiator was changed from 0.1 parts by mass to 0.2 parts by mass and the reaction time was changed from 7 hours to 4 hours to obtain a copolymer having a solid concentration of 20 mass% Was prepared.

The Mw of the copolymer A-4 was 750,000, the Mw / Mn was 3.5, and the residual initiator amount was 1200 ppm.

[Production Example A-5]

The procedure of Production Example A-1 was repeated except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 79 parts by mass, and the amount of acrylic acid (AA) was changed from 7 parts by mass to 3 parts by mass, A polymer solution having a solid content concentration of 20 mass% including A-5 was prepared.

The Mw of the copolymer A-5 was 800,000, the Mw / Mn was 3.4, and the residual initiator amount was 680 ppm.

[Production Example A-6]

The procedure of Production Example A-1 was repeated except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 70 parts by mass and the amount of acrylic acid (AA) was changed from 7 parts by mass to 12 parts by mass, A polymer solution having a solid concentration of 20% by mass containing A-6 was prepared.

The Mw of the copolymer A-6 was 750,000, the Mw / Mn was 3.0, and the residual initiator amount was 630 ppm.

[Production Example A-7]

The procedure of Production Example A-1 was repeated except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 83 parts by mass, and the amount of methyl acrylate (MA) was changed from 18 parts by mass to 10 parts by mass, To prepare a polymer solution having a solid concentration of 20% by mass containing the copolymer A-7.

The Mw of the copolymer A-7 was 800,000, the Mw / Mn was 3.1, and the residual initiator amount was 640 ppm.

[Production Example A-8]

The procedure of Production Example A-1 was repeated except that the amount of n-butyl acrylate (BA) was changed from 75 parts by mass to 53 parts by mass and the amount of methyl acrylate (MA) was changed from 18 parts by mass to 40 parts by mass, To prepare a polymer solution having a solid content concentration of 20% by mass containing the copolymer A-8.

The Mw of the copolymer A-8 was 800,000, the Mw / Mn was 3.4, and the residual initiator amount was 730 ppm.

[Production Example B-1]

In a two-liter four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introducing tube and a cooling tube, 95 parts by mass of methyl methacrylate (MMA) as a polymerizable monomer and 5 parts by mass of dimethylaminoethyl methacrylate And 100 parts by mass of toluene was added as a solvent.

Subsequently, while stirring in a nitrogen gas atmosphere, 3 parts by mass of AIBN was added as a polymerization initiator, and the reaction was carried out at 80 DEG C for 10 hours to prepare a solution having a solid concentration of 50% by mass containing the copolymer B-1.

The Tg of the copolymer B-1 was 99 占 폚, the Mw was 0.5, the Mw / Mn was 1.5, and the residual initiator amount was 50 ppm.

[Production Example B-2]

Except that 95 parts by mass of methyl methacrylate (MMA) was changed to 95 parts by mass of t-butyl methacrylate (t-BMA) to obtain a copolymer having a solid content concentration of 50 mass% Was prepared.

The copolymer B-2 had a Tg of 101 ° C, an Mw of 0.5,000, an Mw / Mn of 1.8, and a residual initiator amount of 60 ppm.

[Production Example B-3]

Production Example B-1 was repeated except that the amount of methyl methacrylate (MMA) was changed from 95 parts by mass to 100 parts by mass and the amount of dimethylaminoethyl methacrylate (DM) was changed from 5 parts by mass to 0 parts by mass. The same procedure was followed to prepare a polymer solution having a solid concentration of 50 mass% including the copolymer B-3.

The copolymer B-3 had a Tg of 105 ° C, an Mw of 0.5,000, an Mw / Mn of 1.5, and a residual initiator amount of 50 ppm.

The polymers obtained in Production Examples are summarized in Table 1.

[Example 1]

(Solid content concentration: 50% by mass) obtained in Production Example B-1 and an epoxy cross-linking agent E-5XM (Soken Chemical Co., Ltd., solid content concentration: 5 mass% %) Were mixed in an amount such that the solid content ratio was 100 parts by mass of the copolymer A-1, 15 parts by mass of the copolymer B-1 and 0.075 parts by mass of E-5XM to obtain a pressure-sensitive adhesive composition.

[Examples 2 to 6 and Comparative Examples 1 to 8]

A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive composition was changed as shown in Table 2. [

The pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were measured and evaluated by the following methods.

(Preparation of pressure-sensitive adhesive sheet)

The pressure-sensitive adhesive composition was coated on a peeled polyethylene terephthalate (PET) film so as to have a thickness of 20 탆 after drying, and dried at 80 캜 for 2 minutes to form a pressure-sensitive adhesive layer.

A PET film having a thickness of 38 mu m peeled off was peeled from the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the PET film and aged for 7 days under conditions of 23 DEG C and 50% RH to form a pressure- Sensitive adhesive sheet.

(Evaluation of reworkability and zipping phenomenon)

The PET film having a thickness of 38 mu m peeled from the pressure-sensitive adhesive sheet was peeled off, and the pressure-sensitive adhesive layer was transferred to a PET film (Diafoil T680E100; manufactured by Mitsubishi Chemical Corporation) having a thickness of 100 mu m and cut into 25 mm width to prepare a test piece. The PET film peeled off from the obtained test piece was peeled off, and the exposed pressure-sensitive adhesive layer was attached to a glass plate, followed by compression bonding with 3 reciprocations of 2 kg rollers. After pressing, the sample was left for 24 hours under the environment of 23 ° C and 50% RH. Thereafter, the pressure-sensitive adhesive sheet was pulled at an angle of 90 ° with respect to the glass plate at a rate of 300 mm / min, Respectively.

· Re-workability

◎: No adhesive remained on the glass plate after peeling off the adhesive sheet

○: The paste did not remain on the glass plate after the peeling of the adhesive sheet, but the patch mark was visible

?: Less than 20% of the attached area is left on the glass plate after peeling off the adhesive sheet

X: More than 20% of the adhesive surface area remains on the glass plate after peeling off the adhesive sheet

· Jeeping

O: No sound is produced when the adhesive sheet is peeled off from the glass plate

X: When the adhesive sheet was peeled off from the glass plate,

(Evaluation of my foamability)

The PET film having a thickness of 38 mu m peeled off from the pressure-sensitive adhesive sheet was peeled off, and the pressure-sensitive adhesive layer was transferred to a PET film (Diafoil T680E100; manufactured by Mitsubishi Chemical Corporation) having a thickness of 100 mu m and cut into a 50 mm x 50 mm width. The peeled PET film was peeled off from the obtained test piece, and the exposed pressure-sensitive adhesive layer was attached to a polycarbonate plate. After leaving for 150 hours under the environment of 80 占 폚, the presence or absence of bubbles was visually determined.

◎: No air bubble

○: There are some bubbles, but there is no problem in actual use

X: Bubbles exist over a wide range

(Evaluation of UV resistance)

The pressure-sensitive adhesive sheet was irradiated with ultraviolet rays (60 W / m ² ) for 168 hours using a UV lamp (Suga Shiken Keiki Energy Energy Xenon Weatherometer type: SC750W).

After the irradiation, the pressure-sensitive adhesive sheet was observed to determine whether or not the surface of the pressure-sensitive adhesive layer had irregularities, that is, whether it was in the form of a citron peel.

○: No citron peel shape

X: Form of citron skin

It was judged that the thing not having the form of the citron peel was also excellent in weather resistance.

Examples and comparative examples are summarized in Table 2.

Claims (3)

(Meth) acrylic acid alkyl ester having a glass transition temperature (Tg) of 0 占 폚 or more and a number of carbon atoms of an alkyl group of 1 to 12 in an amount of 13 to 35 mass%
(Meth) acrylic acid alkyl ester having a glass transition temperature (Tg) of the homopolymer of less than 0 占 폚 and having an alkyl group of 1 to 12 carbon atoms in an amount of 55 to 80 mass%
(Meth) acrylic copolymer (A) which is a copolymer of a monomer component containing 3.5 to 10 mass% of a carboxyl group-containing monomer,
(Meth) acrylic copolymer (B) which is a copolymer of a methacrylic acid alkyl ester having an alkyl group of 1 to 20 carbon atoms and a monomer component containing an amino group-containing monomer,
A pressure-sensitive adhesive composition comprising a cross-linking agent (C)
The pressure-sensitive adhesive composition comprises 1 to 40 parts by mass of a (meth) acrylic copolymer (B) and 0.01 to 5 parts by mass of a crosslinking agent (C) based on 100 parts by mass of the (meth) acrylic copolymer (A)
Wherein the amount of the polymerization initiator contained in 100% by weight of the solid content of the pressure-sensitive adhesive composition is 800 ppm or less. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic copolymer (B) has a weight average molecular weight of 1,000 to 50,000 and a glass transition temperature of 80 ° C or more. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made from the pressure-sensitive adhesive composition according to any one of claims 1 to 3.