JPH0940927A - Acrylic pressure sensitive adhesive composition - Google Patents

Abstract

(57) [Abstract] [Purpose] Scratches and contamination occur during transportation, processing and cutting of pressure sensitive adhesive labels, tapes, sheets, etc., especially metal plates, aluminum sashes, plastic plates, semiconductor wafers, glass, etc. Of an acrylic pressure-sensitive adhesive composition that can be suitably used for forming a pressure-sensitive adhesive layer such as a temporary surface protective material for preventing the occurrence of damage and holding it for preventing damage. . [Structure] An acrylic copolymer obtained by copolymerizing a specific (meth) acrylic acid ester monomer (a) and a hydroxyl group-containing monomer (b) of the following general formula as essential monomers
An acrylic pressure-sensitive adhesive composition comprising (A). Embedded image

Description

Detailed Description of the Invention

[0001]

The present invention relates to pressure-sensitive adhesive labels, tapes, sheets, etc., particularly metal plates, aluminum sashes, plastic plates, semiconductor wafers, glass, etc., which are scratched or contaminated during transportation, processing or cutting. The present invention relates to an acrylic pressure-sensitive adhesive composition that can be suitably used for forming a pressure-sensitive adhesive layer such as a temporary surface protective material for preventing the occurrence of heat and holding it for preventing damage. More specifically, the present invention relates to an acrylic pressure-sensitive adhesive composition, which is obtained by copolymerizing a specific amount of a hydroxyl group-containing monomer having a specific structure as an essential monomer component.

[0002]

2. Description of the Related Art Conventionally, a surface protective material having a pressure-sensitive adhesive layer made of an acrylic copolymer provided on a base material such as paper, cloth, and plastic film has been widely used. In that case,
A hydroxyl group is added to the acrylic copolymer in order to prevent a part of the pressure-sensitive adhesive from remaining on the adherend, so-called "residual residue", or to prevent the adhesive strength to the adherend from becoming too large. It is used by introducing a functional group such as a carboxyl group or the like and crosslinking the copolymer with a crosslinking agent such as a polyisocyanate compound or a metal chelate compound.

However, since the hydroxyl group reacts slowly with the polyisocyanate compound, a curing accelerator such as an amine compound is usually used together. For example, a polyisocyanate compound and an organic solvent solution of such a pressure-sensitive adhesive are used. The compound containing the amine compound has a disadvantage that the pot life is shortened.

Further, in the case of introducing a carboxyl group,
For example, when a non-yellowing type hexamethylene diisocyanate compound is used as the polyisocyanate compound, there is a problem that the viscosity of the pressure-sensitive adhesive solution increases rapidly and the pot life becomes extremely short. When used, there is a problem that the pot life tends to be long, but the adhesive force to the adherend tends to be small.

[0005]

SUMMARY OF THE INVENTION The present inventors have found that pressure-sensitive adhesive compositions, particularly metal plates, aluminum sashes, plastic plates, semiconductor wafers, glass, etc., are damaged or contaminated during transportation, processing and cutting. It has excellent removability as a pressure-sensitive adhesive layer of a temporary surface protective material to prevent the occurrence of damage and to hold it to prevent damage, that is, it has an appropriate adhesive force and excellent cohesive force. However, as a result of research to obtain an acrylic pressure-sensitive adhesive composition having both excellent reactivity with a polyisocyanate compound and good pot life at the time of forming a pressure-sensitive adhesive layer, the result was an essential monomer component. As a result, it was found that an excellent pressure-sensitive adhesive composition having all of these properties can be obtained by copolymerizing a specific amount of a hydroxyl group-containing monomer with a specific structure, and completed the present invention.

[0006]

According to the present invention, in an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer (A), the acrylic copolymer (A) is Quantities (a)-(c),

(A) A (meth) acrylic acid ester monomer represented by the following general formula (1), wherein the homopolymer has a glass transition point of -20 ° C or lower. 50 to 99.9% by weight,

H ₂ C = CR ¹ COOR ² (1) (In the formula, R ¹ represents H or CH ₃ , and R ² represents a linear or branched alkyl group having 2 to 12 carbon atoms.)

(B) 0.1 to 15% by weight of a hydroxyl group-containing monomer represented by the following general formula (2):

Embedded image

[Wherein R ¹ is as defined in the general formula (1), R ³ represents a straight-chain or branched alkyl group having 1 to 10 carbon atoms, and R ⁴ represents hydrogen or a methyl group. , X ¹ represents a linear or branched alkylene group having 1 to 4 carbon atoms.
However, the total number of carbon atoms contained in R ³ , R ⁴ and X ¹ is 3 to 11. ]

(C) A monomer having at least one functional group in addition to the radically polymerizable unsaturated group, which is the above-mentioned monomer
Monomers other than (b) 0 to 15% by weight, and

(D) Copolymerizable with the above monomers (a) to (c),
And 0 to 50% by weight of a comonomer other than the monomers (a) to (c),
(However, the total amount of the monomers (a) to (c) is 100% by weight)

Acrylic copolymer (A) obtained by copolymerizing
An acrylic pressure-sensitive adhesive composition is provided.

The present invention will be described in detail below.

[Acrylic Copolymer (A)] The acrylic copolymer which is the main component of the acrylic pressure-sensitive adhesive composition of the present invention is a (meth) acrylic acid represented by the general formula (1). It is an ester monomer, which is obtained by copolymerizing the (meth) acrylic acid ester monomer (a) whose homopolymer has a glass transition point of -20 ° C or lower as an essential component.

Examples of such (meth) acrylic acid ester monomer (a) include ethyl acrylate and n-
Propyl acrylate, n-butyl acrylate, i-butyl acrylate, n-amyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, i-nonyl acrylate, lauryl acrylate, 2-ethylhexyl methacrylate And C2-12 alkyl ester monomers of (meth) acrylic acid such as lauryl methacrylate. Of these, preferred monomers include n-butyl acrylate, i-butyl acrylate, and n-butyl acrylate.
Examples thereof include octyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate and lauryl methacrylate.

The amount of the monomer (a) used is such that
The total amount of (d) is 100% by weight, and generally 50 to 9 as described above.
The amount is preferably 9.9% by weight, preferably 60 to 99.5% by weight, and more preferably 70 to 99% by weight. The monomer (a)
By appropriately selecting and using within the range of the amount used, the pressure-sensitive adhesive layer obtained has excellent adhesive strength and is excellent in adhesiveness to an adherend, which is preferable.

The acrylic copolymer used in the present invention comprises a monomer (b), that is, a hydroxyl group-containing monomer represented by the following general formula (2), together with the (meth) acrylic acid ester monomer (a). It is obtained by copolymerizing the monomer (b) as an essential component.

[0019]

Embedded image

(In the formulae, R ¹ , R ³ and X ¹ are as defined in claim 1.)

In the above general formula (2), R ³ is a methyl group,
Examples are ethyl group, n-propyl group, i-propyl group, n-butyl group, etc., and X ¹ is methylene group, ethylene group, 2-ethylethylene group, 1,1-dimethylethylene group, 2,2-dimethyl group. Examples are ethylene groups and the like.

Specific examples of such a monomer (b) include:
For example, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 3-methyl-3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-hydroxybutyl (meth) acrylate, 1, 3-dimethyl-3-
Examples thereof include hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth) acrylate and 2-ethyl-3-hydroxyhexyl (meth) acrylate.

The amount of the monomer (b) used is such that the monomers (a) to
The total amount of (d) is 100% by weight, and generally 0.1 to 1 as described above.
5% by weight, preferably 0.5-10% by weight, more preferably 1
It is preferably about 5% by weight. If the amount of the monomer (b) used is too small below the lower limit, it is not preferable because sufficient crosslink density cannot be obtained and the cohesive force becomes insufficient. On the other hand, if the amount exceeds the upper limit, the amount is too large. The adhesive strength tends to be insufficient, which is not preferable.

The acrylic copolymer used in the present invention contains the above-mentioned monomers (a) and (b) and, if necessary, a monomer.
(c), that is, a monomer having at least one functional group in addition to a radically polymerizable unsaturated group (hereinafter sometimes referred to as a functional monomer), which is the above monomer (b) A monomer (c) other than can be copolymerized.

Examples of such a functional monomer (c) include monomers having a functional group such as a carboxyl group, an amide group or a substituted amide group, an amino group or a substituted amino group, and a mercapto group. Among them, in the present invention, one kind or two or more kinds of monomers can be appropriately selected and used.

Specific examples of these functional monomers (c) include, for example, acrylic acid, methacrylic acid, itaconic acid,
Maleic acid, maleic anhydride, fumaric acid, crotonic acid,
Carboxyl group-containing monomers such as citraconic acid and cinnamic acid (preferably acrylic acid, methacrylic acid, itaconic acid); for example, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methyl (meth) Acrylamide, N
-n-butoxymethyl (meth) acrylamide [preferably (meth) acrylamide] -containing amide group- or substituted amide group-containing monomer; for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) Amino group- or substituted amino group-containing monomer such as acrylate, N, N-diethylaminoethyl (meth) acrylate (preferably N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate);

For example, mercapto group-containing monomers such as vinylmethylcaptan and allyl mercaptan; (meth) acrylic acid esters of epoxy group-containing alcohols such as glycidyl (meth) acrylate; glycidyl (meth) allyl, for example (Meth) allyl alcohol or vinyl ether of epoxy group-containing alcohol such as ether or glycidyl vinyl ether; (meth) acrylic acid of hydroxyl group-containing alcohol such as 2-hydroxyethyl (meth) acrylate or 2-hydroxypropyl (meth) acrylate Esters; etc. can be illustrated.

The amount of the functional monomer (c) used is generally 0 to 15% by weight, preferably 0 to 0% by weight, as described above, with the total amount of the monomers (a) to (d) being 100% by weight. It is 10% by weight, more preferably 0 to 5% by weight.

The acrylic copolymer used in the present invention comprises the above-mentioned monomers (a) to (c) and, if necessary, a comonomer.
(d), that is, copolymerizable with the monomers (a) to (c),
Moreover, a comonomer (c) other than the monomers (a) to (c) can be contained as a copolymerization component.

Examples of such a comonomer (d) include methyl (meth) acrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl (meth) acrylate, stearyl (meth) acrylate. , Oleyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate and other (meth) acrylic acid ester monomers other than the above monomer (a); for example, vinyl formate, vinyl acetate, vinyl propionate A saturated fatty acid vinyl ester monomer such as "vinyl versatate" [trade name: manufactured by Shell Co.];
Α, β-C1-C13 linear or branched alkyl ester of α, β-unsaturated dicarboxylic acid such as dibutyl malate, dibutyl fumarate, dibutyl itaconate, dioctyl malate, dioctyl fumarate, dioctyl itaconate; Examples thereof include aromatic vinyl monomers such as styrene, α-methylstyrene, vinyltoluene and ethylvinylbenzene; vinyl cyanide monomers such as (meth) acrylonitrile.

The amount of the comonomer (d) used is generally 0 to 50% by weight, preferably 0 to 30% as described above, with the total amount of the monomers (a) to (d) being 100% by weight. % By weight.

[Production of Acrylic Copolymer (A)] The method for polymerizing the acrylic (co) polymer (A) used in the present invention is as follows.
It is not particularly limited, and known methods such as solution polymerization, emulsion polymerization, and suspension polymerization can be adopted, but an organic solvent-soluble pressure-sensitive adhesive is produced using a (co) polymer mixture obtained by polymerization. In doing so, it is preferable to employ solution polymerization because the treatment process is relatively simple and can be carried out in a short time.

In the solution polymerization, generally, a predetermined organic solvent, a monomer, a polymerization initiator, and optionally a chain transfer agent are charged in a polymerization tank, and a nitrogen stream or a reflux temperature of the organic solvent is used. The reaction is carried out by heating for several hours while stirring. In this case, at least a part of the organic solvent, the monomer, the polymerization initiator and / or the chain transfer agent may be sequentially added.

Examples of the organic solvent for polymerization include, for example,
Benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-
Aromatic hydrocarbons such as xylene, tetralin, decalin and aromatic naphtha; for example, n-hexane, n-heptane, n-
Fatty or alicyclic hydrocarbons such as octane, i-octane, n-decane, dipentene, petroleum spirit, petroleum naphtha, turpentine oil; for example, ethyl acetate, n-butyl acetate, n-amyl acetate, acetic acid 2 -Hydroxyethyl, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, etc. esters; for example, acetone, methyl ethyl ketone, methyl-i-butyl ketone, isophorone, cyclohexanone, methylcyclohexanone, etc. ketones; for example, ethylene Glycol ethers such as glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; Alcohol, ethyl alcohol, n- propyl alcohol, i- propyl alcohol,
Examples thereof include alcohols such as n-butyl alcohol, i-butyl alcohol, s-butyl alcohol and t-butyl alcohol; These organic solvents may be used alone or in combination of two or more.

Examples of the polymerization initiator include benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-t-butyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxy. Organic peroxides such as dicarbonate and t-butyl peroxybivalate; for example, 2,2'-azobis-i-butyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'- Azo compounds such as azobis-4-methoxy-2,4-dimethylvaleronitrile; and the like can be used alone or in combination.

The amount of the polymerization initiator used is generally about 100 parts by weight based on the total amount of the monomers (a) to (d) used for the copolymerization.
It can be in the range of 0.01 to 5 parts by weight, preferably about 0.02 to 2 parts by weight.

The chain transfer agent is, for example,
Cyanoacetic acid; alkyl group having 1 to 8 carbon atoms, cyanoacetic acid alkyl ester; bromoacetic acid; alkyl group having 1 to 8 carbon atoms
Aromatic compounds such as anthracene, phenanthrene, fluorene and 9-phenylfluorene; p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-
Aromatic nitro compounds such as nitrotoluene; benzoquinone, benzoquinone derivatives such as 2,3,5,6-tetramethyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1 , 2,2-Tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tribromomethane, 3-chloro-1
-Halogenated hydrocarbons such as propene; chloral,
Aldehydes such as fullerdehyde; alkyl mercaptans having 1 to 18 carbon atoms; aromatic mercaptans such as thiophenol and toluene mercaptan; mercaptoacetic acid;
C1-10 alkyl esters of mercaptoacetic acid;
Examples thereof include C1-C12 hydroxyalkyl mercaptans; terpenes such as binene and terpinolene.

The amount of the chain transfer agent used is not particularly limited, but is preferably about 0.005 to 3.0 parts by weight per 100 parts by weight of the monomers (a) to (d) in total. .

The polymerization temperature is generally about 30 to 180 ° C.,
It is preferably in the range of about 60 to 150 ° C.

When the unreacted monomer is contained in the polymer obtained by the solution polymerization method or the like, it can be purified by a reprecipitation method with methanol or the like to remove the monomer. Is.

The thus obtained acrylic copolymer for use in the present invention preferably has a glass transition point (hereinafter sometimes abbreviated as Tg) of -30 ° C. or lower, and -40.
It is particularly preferable that the temperature is not higher than ° C. When Tg is not more than the upper limit value, tackiness of the pressure-sensitive adhesive layer to be obtained will not be sufficient, and there will be no inconvenience such as difficulty in sticking to an adherend, which is preferable.

In the present invention, the glass transition point (Tg) of the acrylic copolymer means a value measured by the following method.

Measurement of glass transition point: In a cylindrical cell made of aluminum foil having a thickness of about 0.05 mm and having an inner diameter of about 5 mm and a depth of about 5 mm, about 50% by weight of an acrylic copolymer in an organic solvent solution sample 10 mg is weighed and dried at 100 ° C. for 2 hours to obtain a measurement sample. Seiko Denshi Kogyo Co., Ltd. “SSC-5000” Differential Scanning Calorimeter
Is measured from −150 ° C. at a heating rate of 10 ° C./min.

The acrylic copolymer which can be preferably used in the present invention has a weight average molecular weight (hereinafter sometimes abbreviated as Mw) of 15 to 1,500,000, particularly 25 to 1,000,000. Is preferred. If the Mw value is at least the lower limit value, the pressure-sensitive adhesive layer will have a good balance of the adhesive force and the cohesive force, and if it is at most the upper limit value, the pressure-sensitive adhesive layer will be obtained. When applying the pressure-sensitive adhesive composition solution at the time of forming, a suitable coating viscosity can be obtained without significantly lowering the solid content of the composition solution. Can form an adhesive layer,
Since the amount of organic solvent that volatilizes does not increase too much,
It is preferable in terms of cost and environmental hygiene. Therefore, it is preferable to appropriately select the Mw of the acrylic copolymer within this range. For the same reason, the number average molecular weight (hereinafter sometimes abbreviated as Mn) of the acrylic copolymer is preferably 30,000 to 300,000, particularly preferably 50,000 to 200,000. The "weight average molecular weight" of the copolymer in the present invention
The term means a polystyrene-equivalent value measured by the GPC method.

[Acrylic Pressure-Sensitive Adhesive Composition] The acrylic pressure-sensitive adhesive composition of the present invention may contain various additives, if desired, together with the above-mentioned acrylic copolymer (A). it can. Examples of such additives include:
Examples thereof include tackifiers, pigments, dyes, antioxidants, cross-linking agents and the like, and the use of cross-linking agents is particularly preferable from the viewpoint of improving removability.

In the present invention, examples of the crosslinking agent (B) that can be used together with the acrylic (co) polymer (A) include polyisocyanate compounds, epoxy resins, amino resins, metal chelates and the like. Of these, it is preferable to use a polyisocyanate compound, an epoxy resin, or an amino resin, particularly a polyisocyanate compound.

Examples of the above polyisocyanate compound include m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, m- or p-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate. Aromatic diisocyanate compounds such as; for example, hexamethylene diisocyanate,
Aliphatic or alicyclic diisocyanate compounds such as isophorone diisocyanate, hydrogenated products of the above aromatic diisocyanate compounds, and dimer acid diisocyanates; dimers or trimers of these isocyanate compounds; and these isocyanate compounds, for example, water, ethylene glycol , An adduct with a divalent or trivalent polyol such as trimethylolpropane, and a blocked polyisocyanate obtained by blocking an isocyanate group. Among these polyisocyanate compounds, from the viewpoint of good weather resistance, a water additive of tolylene diisocyanate, hexamethylene diisocyanate, a water additive of xylene diisocyanate, a dimer or trimer of these isocyanate compounds, these isocyanate compounds and water. Or divalent or 3
Particularly preferred are adducts with divalent polyols.

Examples of the epoxy resin include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, hydrogenated bisphenol A type epoxy resins and the like.

In addition to these, novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; for example, polyalkylene polyols (glycerol, sorbitol,
Neopentyl glycol etc.) Glycidyl alkyl ether type epoxy resin such as polyglycidyl ether; eg, glycidyl such as tetraglycidyl diaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, tetraglycidyl-m-xylenediamine Amine epoxy resin;

For example, glycidyl ester epoxy resins such as diglycidyl phthalate, diglycidyl hexahydrophthalate and diglycidyl tetrahydrophthalate; for example, 3,4-epoxycyclohexylmethyl (3 ', 4'
-Epoxycyclohexane) carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3 ', 4'-epoxy-
6'-methylcyclohexanecarboxylate, bis (3,4-
Examples thereof include cycloaliphatic epoxy resins such as epoxy-6-methylcyclohexylmethyl) adipate; and complex-reducing epoxy resins such as triglycidyl isocyanurate and glycidyl glycidoxyalkyl hydantoin.

Further, halides of these epoxy resins; epoxy group-containing resins obtained by reacting these epoxy resins with polybasic acids or polyester polycarboxylic acids;
Examples thereof include various epoxy resins such as polyglycidyl ester of polyester polycarboxylic acid; polyglycidyl ether of polyester polyol.

As the above-mentioned amino resin, alkylated methylolmelamine which is generally used for paints can be particularly preferably used. Above all, those having a methylolation degree in the range of 4 to 6 and an alkylation degree in the range of 3 to 6 are preferable. Examples of the alkyl group include those having 1 to 8 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, octyl group and isomers thereof. Among them, those having 1 to 4 carbon atoms Is preferred.

When these cross-linking agents (B) are used, the amount used is not necessarily limited and can be appropriately selected depending on the intended use of the resulting acrylic pressure-sensitive adhesive composition. In general, 0.05 to 3 equivalents, preferably 0.1 to 2 equivalents per 1 equivalent of the functional group derived from the functional monomers (b) and (c) of the acrylic copolymer (A) contained in An equivalent amount, more preferably an amount of about 0.2 to 1 equivalent can be exemplified. In particular, when the adhesive composition is used for forming a pressure-sensitive adhesive layer such as a temporary surface protective material, the adhesive strength is 10 to 1000 g / 25 mm depending on the purpose of use and the adherend. It is preferable to adjust the amount of the crosslinking agent used so that Generally, the adhesive strength tends to decrease when the amount of the cross-linking agent (B) is increased, and in order to obtain the adhesive strength of about 20 to 30 g / 25 mm, the above-mentioned functional unit of the acrylic copolymer (A) is used. It is also possible to use 2-3 equivalents of the crosslinking agent per equivalent of the functional groups derived from the bodies (b) and (c).

As a method for forming a pressure-sensitive adhesive layer using the acrylic pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive composition is diluted to a coatable viscosity, and this is diluted with paper or paper.
The solvent may be removed by directly coating and drying on a base material such as cloth or plastic film, but usually, on a release sheet such as paper or plastic film which is first subjected to a release treatment with a silicone resin or the like, The pressure-sensitive adhesive composition is applied to an appropriate thickness and dried by heating to form a pressure-sensitive adhesive layer, which is then applied to paper or a plastic film, preferably a plastic film such as polyethylene, polypropylene, polyethylene terephthalate or vinyl chloride. A transfer method can also be adopted.

[0055]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples. Incidentally, the pot life of the pressure-sensitive adhesive composition, the preparation of the test pressure-sensitive adhesive sheet,
The methods for measuring various physical properties such as adhesive strength and cohesive strength are as follows.

(1) Pot life of the pressure sensitive adhesive composition
Measurement After mixing isocyanate type crosslinking agent, solid content is
The pressure-sensitive adhesive composition diluted to 30% by weight,
Let stand at 25 ° C for 8 hours, and observe the state and changes in viscosity.

(2) Preparation of pressure-sensitive adhesive sheet for test On release paper [“Oji Sepak”; manufactured by Shin-Oji Paper Co., Ltd.],
A sample of the pressure-sensitive adhesive composition was applied so that the dry coating amount after drying was about 25 g / m ² , dried at 100 ° C for 90 seconds in a hot air circulation dryer, and then 25 μm polyethylene terephthalate. Transfer to (PET) film to make pressure sensitive adhesive sheet, and then at 23 ℃, 65% RH for 7 days or
What was aged for 30 days is used as a test pressure-sensitive adhesive sheet.

(3) Measurement of adhesive strength SUS 30 polished with # 280 water-resistant abrasive paper specified in JIS R-6253
4 stainless steel plate (hereinafter sometimes abbreviated as SUS)
In addition, the test piece cut out from the pressure-sensitive adhesive sheet for test prepared in the above (1) was pressure-bonded according to the method of JIS Z-0237, and after 1 hour, 23 ° C., 65% RH, and a peeling speed of 300 mm / min. The peel strength (g / 25 mm) is measured with.

(4) Measurement of Cohesive Strength A test piece cut out from the test pressure-sensitive adhesive sheet prepared in (1) above was applied to a SUS plate treated in the same manner as in (2) above, and its sticking area was 25. Stick it so that it becomes × 25mm ² , and attach a 2kg roller to 1
It crimped back and forth 0 times. Place a static load of 1 kg on the sample in a constant temperature bath at 80 ° C and measure the time until the load falls.

Reference Example 1 In a separable flask equipped with a reflux condenser, a thermometer, a stirrer and a sequential dropping device, 50 parts by weight of ethyl acetate (EAc) as an organic solvent for initial addition and azobisiso as a polymerization initiator were added. Add 0.0125 parts by weight of butyronitrile (AIBN), then 97 parts by weight of n-butyl acrylate (BA) and 2-
25% by weight of a monomer mixture consisting of 3 parts by weight of hydroxybutyl methacrylate (HBMA) was added and heated, and polymerization was carried out at a reflux temperature (about 80 ° C.) for about 20 minutes. Then, under a reflux temperature condition, the remaining amount of the monomer mixture of 75% by weight and a polymerization initiator solution consisting of 12.5 parts by weight of EAc and 0.125 parts by weight of AIBN were sequentially added dropwise over about 90 minutes, and further about 30 minutes at EAc 12.5 parts.
A polymerization initiator solution consisting of 1 part by weight and 0.25 part by weight of AIBN is added and aged, and then 75 parts by weight of toluene is added to dilute the solution to a solid content of about 40% by weight and a viscosity of 3210 cps (B-type viscometer, 25
C., 10 rpm; viscosity measurement conditions were the same below) to obtain an acrylic copolymer (A) solution. The Mn of this copolymer is about 123,000,
Mw was about 550,000 and Tg was -55 ° C.

Reference Example 2 An acrylic copolymer was prepared in the same manner as in Reference Example 1, except that 96.5 parts by weight of BA, 3 parts by weight of HBMA and 0.5 part by weight of acrylamide (AAm) were used instead of 97 parts by weight of BA and 3 parts by weight of HBMA. A polymer (A) solution was obtained. Monomer composition used,
The addition method of the monomer mixture, the type of the organic solvent used and the addition method thereof, and the type of the polymerization initiator and the addition method thereof are shown in Table 1, the viscosity of the obtained copolymer, the solid content, M
The values of w, Mn and Tg are shown in Table 2.

Reference Example 3 Instead of using 3 parts by weight of HBMA in Reference Example 1, 2-
An acrylic copolymer (A) solution was obtained in the same manner except that 3 parts by weight of hydroxyethyl methacrylate (HEMA) was used. The monomer composition used, the addition method of the monomer mixture, the type of the organic solvent used and the addition method thereof, the type of the polymerization initiator and the addition method thereof are shown in Table 1, and the viscosity of the obtained copolymer is shown. , Solid content, Mw, Mn and Tg values are shown in Table 2.

Reference Example 4 In Reference Example 1, instead of using 3 parts by weight of HBMA, 3 parts by weight of acrylic acid (AA) was used, and 35 parts by weight of EAc and 0.125 parts by weight of AIBN were used as a polymerization initiator solution for sequential dropping. Using toluene as a polymerization initiator solution for aging.
An acrylic copolymer (A) solution was obtained in the same manner as above, except that 40 parts by weight was used instead of using 75 parts by weight of toluene as a diluting organic solvent. The monomer composition used, the addition method of the monomer mixture, the type of the organic solvent used and the addition method thereof, the type of the polymerization initiator and the addition method thereof are shown in Table 1, and the viscosity of the obtained copolymer is shown. , Solid content, Mw, Mn and Tg values are shown in Table 2.

[0064]

[Table 1]

[0065]

[Table 2]

Example 1 250 parts by weight of the acrylic copolymer (A) solution obtained in Reference Example 1 (about 100 parts by weight as an acrylic copolymer) was added with an isocyanate crosslinking agent (B) "Coronate HX". [Urethane prepolymer composed of trimer of hexamethylene diisocyanate; manufactured by Nippon Polyurethane Co., Ltd.] 1 part by weight [0.7 equivalent to 1 equivalent of functional group in acrylic copolymer (A)] is mixed with stirring. An acrylic pressure-sensitive adhesive composition was obtained.

The obtained pressure-sensitive adhesive composition had a solid content of
The mixture was diluted with EAc to 30% by weight, a pressure-sensitive adhesive sheet was prepared according to the above method, and various physical properties tests were conducted. Table 3 shows the pot life of the pressure-sensitive adhesive composition and the results of various physical property tests of the pressure-sensitive adhesive sheet.

Example 2 Instead of using 1 part by weight of the isocyanate cross-linking agent (B) "Coronate HX" in Example 1, 1.4 parts by weight [based on 1 equivalent of functional groups in the acrylic copolymer (A)] And 1 equivalent] were used to obtain an acrylic pressure-sensitive adhesive composition in the same manner, and various physical property tests were conducted in the same manner. Table 3 shows the pot life of the pressure-sensitive adhesive composition and the results of various physical property tests of the pressure-sensitive adhesive sheet.

Example 3 and Comparative Examples 1-2 In Example 1, the acrylic copolymer (A) of Reference Example 1 was used.
Instead of using, the acrylic copolymers of Reference Examples 2 to 4
An acrylic pressure-sensitive adhesive composition was obtained in the same manner except that (A) was used, and various physical property tests were conducted in the same manner.
Table 3 shows the pot life of the pressure-sensitive adhesive composition and the results of various physical property tests of the pressure-sensitive adhesive sheet.

[0070]

[Table 3]

[0071]

The acrylic pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer (A) obtained by copolymerizing a specific amount of a hydroxyl group-containing monomer having a specific structure as an essential monomer component. And preferably further contains a specific amount of a crosslinking agent, especially an isocyanate crosslinking agent.

The acrylic pressure-sensitive adhesive composition of the present invention is constituted as described above, whereby a pressure-sensitive adhesive label, tape, sheet, etc., particularly a metal plate, an aluminum sash, a plastic plate, a semiconductor wafer, etc. Transportation of glass,
It can be suitably used for forming a pressure-sensitive adhesive layer such as a temporary surface protective material for preventing damage and contamination during processing and cutting, and for fixing and holding it for preventing damage. it can.

Claims (5)

[Claims] 1. An acrylic pressure-sensitive adhesive composition containing an acrylic copolymer (A), wherein the acrylic copolymer (A) comprises the following monomers (a) to (c): (a) a (meth) acrylic acid ester monomer represented by the following general formula (1), wherein the homopolymer has a glass transition point of −
(Meth) acrylic acid ester monomer having a temperature of 20 ° C or lower 50 to 9
9.9% by weight, H ₂ C = CR ¹ COOR ² (1) (In the formula, R ¹ represents H or CH ₃ , and R ² represents a linear or branched alkyl group having 2 to 12 carbon atoms.) (B) Hydroxyl group-containing monomer represented by the following general formula (2) 0.1 to 1
5% by weight, [Chemical formula 1] [In the formula, R ¹ is as defined in the general formula (1), R ³ represents a linear or branched alkyl group having 1 to 10 carbon atoms,
R ⁴ represents hydrogen or a methyl group, and X ¹ represents a linear or branched alkylene group having 1 to 4 carbon atoms. However, R ³ and R ⁴
And the total number of carbon atoms of X ¹ is 3 to 11. (C) A monomer having at least one functional group in addition to the radical-polymerizable unsaturated group, which is 0 to 15% by weight of a monomer other than the monomer (b), and (d) ) Copolymerizable with the monomers (a) to (c), and the monomer
(a) to (c) Comonomers 0 to 50% by weight, [wherein the total of monomers (a) to (c) is 100% by weight] copolymerized acrylic copolymer An acrylic pressure-sensitive adhesive composition characterized by being a combination (A). 2. The acrylic pressure-sensitive adhesive composition according to claim 1, wherein the glass transition point of the acrylic copolymer (A) is −30 ° C. or lower. 3. The acrylic pressure-sensitive adhesive composition according to claim 1, which further contains a crosslinking agent (B). 4. The acrylic pressure-sensitive adhesive composition according to claim 3, wherein the crosslinking agent (B) is a polyisocyanate compound. 5. A cross-linking agent (B) content of acrylic copolymer
The acrylic pressure-sensitive adhesive composition according to claim 3 or 4, which is 0.05 to 3 equivalents relative to 1 equivalent of the functional group in (A).