JP2002069409A - Removable adhesive composition - Google Patents

Abstract

(57) [Problem] To provide a re-peelable pressure-sensitive adhesive composition which is excellent in initial adhesive strength, durability and removability, and further excellent in stain resistance and non-corrosion after peeling. SOLUTION: A re-peelable type comprising an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, a photopolymerization initiator (B) and a crosslinking agent (C). Adhesive composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for temporarily protecting a surface of a metal plate, a glass plate, a plastic plate, or the like during transportation, processing, cutting, etc., for preventing scratches and contamination, or for temporarily bonding. The present invention relates to a removable pressure-sensitive adhesive composition used as a pressure-sensitive adhesive for a pressure-sensitive adhesive sheet.

[0002]

2. Description of the Related Art In recent years, an adhesive sheet has been temporarily used as a protective sheet on a surface of a metal plate, a glass plate, a plastic plate, or the like in order to prevent rust on the surface (in the case of a metal plate), dirt or damage. Or, an adhesive sheet is used for applications such as temporary bonding.

[0003] The pressure-sensitive adhesive used for these pressure-sensitive adhesive sheets has a sufficient adhesive force when applied to an adherend, and then has a sufficient adhesive force when peeled (cured by ultraviolet irradiation or the like). It is necessary to have the property that the surface of the adherend is reduced and there is no contamination (residual adhesive) on the surface of the adherend. Further, when a metal plate is used as the adherend, non-corrosiveness to the metal surface is also required. is there.

For example, JP-A-61-28572 discloses a radiation-curable pressure-sensitive adhesive comprising an acrylic pressure-sensitive adhesive and a urethane acrylate-based oligomer. An adhesive comprising an acrylic adhesive and a urethane acrylate oligomer having a molecular weight of 3000 to 10,000 has been proposed.

In Japanese Patent Application Laid-Open No. 53-121832, as a photocurable pressure-sensitive adhesive used for surface protection, a polymer mainly composed of a pressure-sensitive adhesive has two or more unsaturated bonds having photoreactivity per molecule. Those, or those obtained by mixing a low-molecular compound such as a photosensitive monomer in a normal pressure-sensitive adhesive, are described in JP-A-1-251737, in which a carboxyl group, a hydroxyl group, an amino group, a cyclic acid anhydride group, An acrylic polymer having one or more functional groups selected from an epoxy group and an isocyanate group and an ethylenically unsaturated double bond, and a radiation-curable acrylic containing a compound that reacts with the functional group as a main component JP-A-2-187478 proposes an acrylic polymer having a radiation-polymerizable unsaturated group in the molecule and a radiation-polymerizable polymer. JP-A-2000-44890 discloses a pressure-sensitive adhesive containing a polyfunctional oligomer as a main component, which contains an ethylenically unsaturated group-containing acrylic pressure-sensitive adhesive, a urethane acrylate compound, a photopolymerization initiator, and a crosslinking agent. Agents have been proposed.

Further, Japanese Patent Application Laid-Open No. 2000-44889 proposes an adhesive containing an acetoacetyl group-containing acrylic adhesive, a urethane acrylate compound, a photopolymerization initiator, and a crosslinking agent.

[0007]

However, as a result of examining the above-disclosed technology, and in the disclosed technology, although a decrease in the adhesive strength at the time of re-peeling (after curing) the adhesive is recognized, after the re-peel, There is a problem that the pressure-sensitive adhesive remains (adhesive residue) on the surface of the adherend and becomes contaminated, and in the disclosed technology, a system containing a carboxyl group as a functional group is highly corrosive to metals, and a system containing a hydroxyl group There is a problem that sufficient adhesive strength cannot be obtained before curing, and that the adhesive sheet is inferior in durability such as floating or peeling from an adherend when used for a long time at a high temperature.

[0008] Furthermore, in the techniques disclosed in (1) and (2), an acrylic pressure-sensitive adhesive containing a carboxyl group as a functional group may cause a problem of corrosiveness to metal and a problem of contamination due to adhesive residue. Also, there is a possibility that a problem of contamination due to adhesive residue may occur in the disclosed technology, and the disclosed technology is not yet satisfactory and further improvement is required.

Under such circumstances, the present invention provides a re-peelable adhesive which is excellent in initial adhesive strength, durability under high temperature and removability, and is excellent in stain resistance and non-corrosion after peeling. It is intended to provide an agent composition.

[0010]

Means for Solving the Problems However, the inventors of the present invention have conducted intensive studies to solve such problems, and as a result, have found that an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group (A), Polymerization initiator (B) and crosslinking agent (C)
The present inventors have found that a re-peelable pressure-sensitive adhesive composition containing the above meets the above object, and completed the present invention.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. The acrylic pressure-sensitive adhesive (A) used in the present invention is:
Compound (a2) having an acetoacetyl group-containing acrylic polymer (a1) having a functional group in the molecule and a functional group reactive with the above functional group and an ethylenically unsaturated group in the molecule
(Referred to as “functional group-containing unsaturated compound”) to react with each other in the molecule of the acetoacetyl group-containing acrylic polymer (a1),
Usually, it has a structure in which an ethylenically unsaturated group is introduced into a side chain.

The acetoacetyl group-containing acrylic polymer (a1) having a functional group in the molecule can be produced, for example, by the following method.

(1) Copolymerize an ethylenically unsaturated monomer containing an acetoacetyl group (a), an ethylenically unsaturated monomer containing a functional group (b), and, if necessary, other ethylenically unsaturated monomers (c). . Here, the acetoacetyl group-containing ethylenically unsaturated monomer (a) is produced, for example, by the following method.

(1-1) Diketene is reacted with the functional group-containing ethylenically unsaturated monomer (d). As the functional group, a hydroxyl group, an amide group, a urethane group, an amino group,
Suitable examples of the functional group-containing ethylenically unsaturated monomer (d) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxy-3-chloropropyl acrylate, and the like. It is.

(1-2) Transesterification of the functional group-containing ethylenically unsaturated monomer (d) with acetoacetic ester.

The reaction of diketene in the case of the above (1-1) is carried out without using a catalyst, a tertiary amine, an acid (such as sulfuric acid), a basic salt (such as sodium acetate), an organometallic compound (such as dibutyltin laurate). Etc.) in the presence of a catalyst. The reaction of the above (1-2) acetoacetic ester is preferably performed in the presence of a transesterification catalyst such as calcium acetate, zinc acetate, lead oxide and the like.

Examples of the functional group-containing ethylenically unsaturated monomer (b) include acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide N-glycolic acid, and cinnamic acid. Carboxyl group-containing unsaturated monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl acrylate,
2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, tetrahydrofurfuryl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, diethylene glycol acrylate, polyethylene glycol acrylate, N-methylol acrylamide, N-methylol Hydroxy group-containing unsaturated monomers such as methacrylamide, glycidyl group-containing unsaturated monomers such as glycidyl methacrylate and allyl glycidyl methacrylate, isocyanate group-containing unsaturated monomers such as 2-acryloyloxyethyl isocyanate and 2-methacryloyloxyethyl isocyanate, acrylamide, methacryl Amide, N- (n-butoxyalkyl)
Amide group-containing unsaturated monomers such as acrylamide and N- (n-butoxyalkyl) methacrylamide; amino group-containing unsaturated monomers such as acrylamido-3-methylbutylmethylamine, dimethylaminoalkylacrylamide and dimethylaminoalkylmethacrylamide; ethylene Olefin sulfonic acids such as sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid, 2-acrylamide-
Examples include sulfonic acid group-containing unsaturated monomers such as 2-methylpropanesulfonic acid, styrenesulfonic acid and salts thereof. Among them, a carboxyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, a glycidyl group-containing unsaturated monomer, an isocyanate group-containing unsaturated monomer, and an amide group-containing unsaturated monomer are preferably used.

Other ethylenically unsaturated monomers (c)
Examples thereof include (meth) acrylic acid esters, in particular, alkyl (meth) acrylic acid esters having 1 to 12 carbon atoms, preferably 4 to 12 carbon atoms, and specific examples thereof include n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth)
Acrylate, n-propyl (meth) acrylate, n
-Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, and the like.

Further, an ethylenically unsaturated monomer (c)
As 2-methoxyethyl (meth) acrylate, 3
Alkyl vinyl ethers such as -methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallylvinylketone, N-vinylpyrrolidone, vinyl propionate, vinyl stearate , Vinyl chloride, vinylidene chloride, vinyl acetate, styrene and the like.

Thus, the acetoacetyl group-containing ethylenically unsaturated monomer (a), the functional group-containing ethylenically unsaturated monomer (b), and the other ethylenically unsaturated monomer (c) are copolymerized to form a functional group in the molecule. An acetoacetyl group-containing acrylic polymer (a1) having a group is obtained.

In the copolymerization, the ethylenically unsaturated monomer containing an acetoacetyl group (a), the ethylenically unsaturated monomer containing a functional group (b), and other ethylenically unsaturated monomers (c) are dissolved in an organic solvent. ) And a polymerization initiator (azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, etc.) are mixed or added dropwise, and refluxed or at 50 to 90 ° C.
Polymerize for ~ 20 hours.

The content ratio of the ethylenically unsaturated monomer having an acetoacetyl group (a), the ethylenically unsaturated monomer having a functional group (b), and the other ethylenically unsaturated monomer (c) is not particularly limited. Has an acetoacetyl group-containing ethylenically unsaturated monomer (a) of 0.1%.
01 to 40% by weight (preferably 0.1 to 10% by weight),
0.05 of functional group-containing ethylenically unsaturated monomer (b)
-30% by weight (preferably 0.1-20% by weight), and the other ethylenically unsaturated monomer (c) is preferably 50-99% by weight (preferably 60-92% by weight).

The method for obtaining the acetoacetyl group-containing acrylic polymer (a1) is not limited to the above method (1), but may be obtained, for example, by the following methods (2) to (4). The acetoacetyl group-containing acrylic polymer to be obtained can also be prepared by including a functional group-containing ethylenically unsaturated monomer (b).

(2) Diketene is reacted with the acrylic copolymer containing the functional group-containing ethylenically unsaturated monomer (d). The reaction may be performed, for example, by adding diketene to the copolymer in solution and heating and stirring. (3) A transesterification reaction between an acetoacetate ester and an acrylic copolymer containing an ethylenically unsaturated monomer component containing a functional group (hydroxyl group or ester group) capable of transesterification and an acetoacetate ester. (4) Graft polymerization or coexistence polymerization of an acetoacetyl group-containing ethylenically unsaturated monomer on the acrylic copolymer.

Next, the acetoacetyl group-containing acrylic polymer (a1) having a functional group in the molecule is added to a compound having a functional group that reacts with the functional group and an ethylenically unsaturated group in the molecule. (A2) (referred to as a functional group-containing unsaturated compound) is reacted.

Examples of the functional group-containing unsaturated compound (a2) include the aforementioned carboxyl group-containing unsaturated monomers, hydroxyl group-containing unsaturated monomers, glycidyl group-containing unsaturated monomers,
Examples include isocyanate group-containing unsaturated monomers, amide group-containing unsaturated monomers, amino group-containing unsaturated monomers, sulfonic acid group-containing unsaturated monomers, and the like. Further, glycidol di (meth) acrylate, pentaerythritol di (meth) Acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, trimethylolpropanedi A monomer having two or more ethylenically unsaturated groups and a hydroxyl group such as (meth) acrylate may also be used, and is appropriately selected according to the reactivity between the reactive group and the functional group.

For example, when the functional group in the acetoacetyl group-containing acrylic polymer (a1) is a carboxyl group, a glycidyl group-containing unsaturated monomer or an isocyanate group-containing unsaturated monomer is used, and when the functional group is a hydroxyl group, isocyanate is used. When the group-containing unsaturated monomer is a carboxyl group-containing unsaturated monomer or an amide group-containing unsaturated monomer when the functional group is a glycidyl group, a glycidyl group-containing unsaturated monomer is used when the functional group is an amino group. Can be

The reaction between the acetoacetyl group-containing acrylic polymer (a1) having a functional group in the molecule and the functional group-containing unsaturated compound (a2) is not particularly limited. The reaction may be carried out for 50 hours, and a catalyst may be used as needed.

The acrylate polymer containing an acetoacetyl group having a functional group in the molecule (a1) may have all reactive active sites reacted with the unsaturated compound having a functional group (a2). It is preferable to leave the reaction active site from the viewpoint of improving the adhesive strength and the cohesive strength.

Thus, the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group of the present invention is obtained. In the acrylic pressure-sensitive adhesive (A),
In the present invention, the number of ethylenically unsaturated groups in the acrylic pressure-sensitive adhesive (A) per 100,000 weight average molecular weight is particularly preferably 0.1 to 100, and more preferably 1 to 5
The number is preferably 0, and particularly preferably 1 to 10. When the number is less than 0.1, the adhesive strength after irradiation with ultraviolet rays or radiation is insufficiently reduced, and when the number exceeds 100, the light stability before irradiation with ultraviolet rays or radiation deteriorates or the cured product after irradiation. Becomes too hard, and cracking and chipping of the adhesive occur at the time of peeling, which is not preferable.

In the acrylic pressure-sensitive adhesive (A), in the present invention, the content of the acetoacetyl group in the acrylic pressure-sensitive adhesive (A) is particularly preferably 0.01 to 40% by weight. Is 0.1 to 25% by weight, especially 1 to 25% by weight.
It is preferably 15% by weight. When the content is 0.
If the amount is less than 01% by weight, the pressure-sensitive adhesive composition may remain on the adherend surface during re-peeling. If the amount exceeds 40% by weight, the pressure-sensitive adhesive composition becomes too hard, which is not preferable.

The weight average molecular weight of the acrylic pressure-sensitive adhesive (A) is not particularly limited, but is preferably from 200,000 to 1.5 million, more preferably from 400,000 to 1,000,000. When the weight-average molecular weight is less than 200,000, the pressure-sensitive adhesive composition tends to remain on the adherend surface during re-peeling, and the
If it exceeds 10,000, the viscosity becomes too high and the handling becomes poor, which is not preferable.

The photopolymerization initiator (B) used in the present invention is not particularly restricted but includes, for example, benzoin, isopropylbenzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, Acetophenone diethyl ketal, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2
-Methyl-1-phenylpropan-1-one and the like, among which benzyldimethylketal, 1-hydroxycyclohexylphenylketone, 2-hydroxy-
2-Methyl-1-phenylpropan-1-one is preferably used.

The content of the photopolymerization initiator (B) is 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group.
Parts by weight, more preferably from 1.0 to 1.0 parts by weight.
5.0 parts by weight. When the content is less than 0.1 part by weight, the decrease in adhesive strength (removability) after irradiation with ultraviolet rays or irradiation rays is insufficient, and when it exceeds 10 parts by weight, the photopolymerization initiator ( B) remains and causes contamination, which is not preferable.

The crosslinking agent (C) used in the present invention is not particularly limited.
Epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, Epoxy compounds such as polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-
Tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), N, N′-hexamethylene-1,6-
Aziridine compounds such as bis (1-aziridinecarboxamide), hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaptoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, etc. Melamine compound, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4-diisocyanate , Isophorone diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalenediisocyanate, trime Tolylene diisocyanate adduct of trimethylolpropane, xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, methylene bis (4-phenyl methane) isocyanate compound triisocyanates such as glyoxal, malondialdehyde, succindialdehyde aldehyde,
Aldehyde compounds such as maleic dialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde, hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, polyamide, etc. Amine compounds, aluminum, iron, copper, zinc,
Tin, titanium, nickel, antimony, magnesium,
Metal chelate compounds such as acetylacetone and acetoacetyl ester coordination compounds of polymetals such as vanadium, chromium, and zirconium are exemplified. Among them, isocyanate compounds, amine compounds, and metal chelate compounds are preferably used.

The content of the crosslinking agent (C) is 0 to 100 parts by weight of the total of the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group and the photopolymerization initiator (B). It is preferably 0.005 to 10 parts by weight, more preferably 0.05 to 4 parts by weight. If the content is less than 0.005 parts by weight, the pressure-sensitive adhesive composition will remain on the adhered surface at the time of re-peeling after irradiation with ultraviolet rays or radiation, causing contamination, and if it exceeds 10 parts by weight,
The curing proceeds before irradiation with ultraviolet rays or radiation, and the adhesive strength after irradiation with ultraviolet rays or radiation may not be sufficiently reduced, which is not preferable.

The removable pressure-sensitive adhesive composition of the present invention comprises an acrylic pressure-sensitive adhesive (A), a photopolymerization initiator (B), and a crosslinking agent (C) containing the above-mentioned ethylenically unsaturated group and acetoacetyl group. However, as a method for preparing the removable pressure-sensitive adhesive composition, the above-mentioned (A) to (C) may be blended (mixed), and the blending order and the like are not particularly limited. .

The solvent used at this time includes an acrylic pressure-sensitive adhesive (A), a photopolymerization initiator (B) and a crosslinking agent (C).
There is no particular limitation as long as it dissolves, but esters such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate, ketones such as acetone and methyl isobutyl ketone, and aromatic compounds such as toluene and xylene. No. However, ethyl acetate and toluene are preferably used from the viewpoints of solubility, drying property, price and the like.

Thus, the removable pressure-sensitive adhesive composition of the present invention is obtained, but within the range not impairing the effects of the present invention.
Pressure-sensitive adhesives other than the acrylic pressure-sensitive adhesive (A), urethane resin, rosin, rosin ester, hydrogenated rosin ester, phenolic resin, aromatic modified terpene resin, aliphatic petroleum resin, alicyclic petroleum resin, styrene-based Resins, tackifiers such as xylene resins, known additives, and compounds that cause coloration or discoloration by irradiation with ultraviolet light or radiation can be added.

The re-peelable pressure-sensitive adhesive composition of the present invention is usually applied to a substrate sheet or the like and is often put to practical use as a pressure-sensitive adhesive sheet or a pressure-sensitive adhesive tape. First, the re-peelable pressure-sensitive adhesive composition of the present invention as it is or with an appropriate organic solvent, the concentration is adjusted, and applied to the treated surface of the substrate subjected to silicon treatment or the like, or directly to the substrate. Coating, for example, 80 to 105
The adhesive layer can be formed by drying by heat treatment or the like at 30 ° C. for 30 seconds to 10 minutes.

The substrate is not particularly limited as long as it is a film through which ultraviolet rays and the like can pass. For example, polyvinyl chloride, polybutene, polybutadiene, polyurethane, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polyethylene, polypropylene, Examples include transparent films such as ethylene-propylene copolymer, polymethylpentene, and polybutylene terephthalate, and colored films capable of transmitting ultraviolet light.

The removable pressure-sensitive adhesive composition of the present invention can be used for temporary surface protection for preventing scratches and contamination during transportation, processing, cutting and the like of metal plates, glass plates, plastic plates and the like. It is used as an adhesive such as an adhesive sheet for temporary bonding.

For example, when the surface of the adherend is protected, it has a sufficient pressure-sensitive adhesive, and after processing such as transportation, processing, and cutting, is performed from the side of the base material such as a pressure-sensitive adhesive sheet or a pressure-sensitive adhesive tape. It is cured by irradiating it with ultraviolet rays or radiation, and its adhesive strength is reduced and it is removed again.

As a light source for performing the ultraviolet irradiation, a high pressure mercury lamp, an ultra high pressure mercury lamp, a carbon arc lamp, a xenon lamp,
Metal halide lamps, chemical lamps, black lights and the like are used. In the case of a high-pressure mercury lamp, for example, 5
３3000 mJ / cm ² , preferably 10-500 mJ
/ Cm ² . The irradiation time depends on the type of light source,
Although it depends on the distance between the light source and the coating surface, the coating thickness, and other conditions, it is usually several seconds, and in some cases, a fraction of a second. In the case of electron beam irradiation, for example, 50 to 100
Using an electron beam having an energy in the range of 0 Kev,
The irradiation amount is preferably 50 Mrad.

Adhesion before and after curing (JIS Z 0237)
180 degrees peel strength) varies depending on the type of the base material, but before curing, it is 200 g / 25 mm or more, preferably 500 g / 25 mm or more, and after irradiation (at the time of re-peeling), 5 to 5 g.
About 30 g / 25 mm is preferable. In the case of temporary protection of the semiconductor wafer, it is preferably 150 g / 25 mm or more, preferably 300 g / 25 mm or more before curing, and about 5 to 30 g / 25 mm after irradiation (at the time of re-peeling).

Thus, the removable pressure-sensitive adhesive composition of the present invention comprises an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, a photopolymerization initiator (B), and a crosslinking agent (C). Because it contains, it has excellent initial adhesive strength, durability under high temperature, excellent re-peelability, and also shows excellent effects on post-peeling stain resistance and non-corrosion. It is very useful as an adhesive used for an adhesive sheet for temporary surface protection or temporary adhesion such as a plastic plate or an adhesive sheet for fixing a semiconductor in a dicing process such as a semiconductor wafer.

[0047]

The present invention will be specifically described below with reference to examples. In the examples, “%” and “parts” mean on a weight basis unless otherwise specified.

Example 1 [Acetacetyl group-containing acrylic polymer having a functional group in the molecule (a1)] 150 parts of 2-hydroxyethyl methacrylate was charged, and 0.05 part of triethylamine was added as a catalyst for the diketene addition reaction. After the temperature was raised to 60 ° C., 96.9 parts of diketene (equivalent to 2-hydroxyethyl methacrylate) was added dropwise with stirring over 2 hours, and the reaction was further continued for 5 hours to remove the hydroxyl group of 2-hydroxyethyl methacrylate. Acetoacetylated,
Acetoacetylated 2-hydroxyethyl methacrylate in which all of the hydroxyl groups of 2-hydroxyethyl methacrylate were acetoacetylated was obtained.

Next, 70 parts of butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, 10 parts of the above acetoacetylated 2-hydroxyethyl methacrylate and 80 parts of ethyl acetate were charged, and after heating under reflux, azobisisopropane was used as a polymerization initiator. Add 0.07 parts of butyronitrile,
After reacting for 3 hours at the reflux temperature of ethyl acetate, 0.07 parts of azobisisobutyronitrile and 5 parts of toluene were added, and the reaction was further continued for 4 hours, diluted with toluene and diluted with an acetoacetyl group-containing acrylic polymer (a1). Solution (resin content 40%, viscosity 1
2000 mPa · s (25 ° C.).

[Acrylic pressure-sensitive adhesive containing ethylenically unsaturated group and acetoacetyl group (A)] Dilauryl was added to 100 parts of the obtained acetoacetyl group-containing acrylic polymer (a1) solution (resin content: 40%). 0.004 part of di-n-butyltin acid, hydroquinone monoethyl ether 0.0
06 parts and 6.6 parts of 2-methacryloyloxyethyl isocyanate (a2) as a functional group-containing unsaturated compound were charged, reacted at 50 ° C. for 20 hours, finally diluted with toluene, and ethylenically unsaturated in the side chain. Adhesive (A) solution in which a group is added to 2-hydroxyethyl acrylate at 60 mol% (resin content 35%, viscosity 190
0 mPa · s (25 ° C.)).

The acrylic adhesive (A) has a weight average molecular weight of 550,000, the number of ethylenically unsaturated groups is 2.6 per 10,000 weight average molecular weight, and the content of acetoacetyl group is 8.6 weight. %Met. In addition, the weight average molecular weight was measured by gel permeation chromatography.

[Production of Removable Adhesive Composition] In a room shielded from ultraviolet rays, 30 parts of toluene, 100 parts of the above acrylic adhesive (A) solution (resin content 35%) were placed in a 250 ml polyethylene container, 1 part of 1-hydroxycyclohexylphenyl ketone (B) (“Irgacure 184” manufactured by Ciba-Geigy Japan) and a 55% ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane (C) (“Coronate L” manufactured by Nippon Polyurethane Co., Ltd.) -55
E ") 0.25 part was added and stirred to obtain a removable pressure-sensitive adhesive composition solution as a uniform solution. With respect to the obtained removable pressure-sensitive adhesive composition, pressure-sensitive adhesive sheets were prepared as described below, and the following physical properties were evaluated.

[Preparation of Pressure-sensitive Adhesive Sheet] In a state where ultraviolet rays are blocked, a re-peelable pressure-sensitive adhesive composition solution is applied to a 38 μm-thick polyester film subjected to a silicone release treatment so that the thickness after drying becomes 20 μm. At 100 ° C. for 2 minutes. Thereafter, the adhesive sheet was transferred onto a 110 μm polyolefin film as a substrate and aged at 40 ° C. for 3 days to obtain a pressure-sensitive adhesive sheet.

(Initial Adhesive Strength) The above-mentioned pressure-sensitive adhesive sheet was adhered to an adherend (SUS plate, glass plate), left for 0.5 hours, and then peeled at 180 ° before ultraviolet irradiation according to JIS Z 0237. The strength (g / 25 mm) was measured.

(Durability) The above pressure-sensitive adhesive sheet was adhered to an adherend (
SUS plate, glass plate) with an area of 25 mm x 2
The adhesive sheet was adhered so as to have a thickness of 5 mm, left at 20 ° C. for 1 day, and further left at 60 ° C. for 1 day. After 5 cycles, the state of floating of the pressure-sensitive adhesive sheet from the adherend was observed. The evaluation criteria are as follows. ○ ・ ・ ・ Floating was not observed × ・ ・ ・ Floating was observed

(Removability) The above pressure-sensitive adhesive sheet was adhered to an adherend (
(SUS plate, glass plate), left for 1 hour, and then irradiated with ultraviolet light (250 mJ / cm with a high-pressure mercury lamp)
² ) and leave it for 0.5 hours, then follow JIS Z
According to 0237, the 180-degree peel strength (g / 25 mm) after ultraviolet irradiation was measured.

(Stain resistance) The above-mentioned pressure-sensitive adhesive sheet was adhered to the surface of a 4-inch square adherend (SUS plate, glass plate) to which no foreign matter was adhered, and was placed under the conditions of 23 ° C. and 65% RH.
After standing for an hour, irradiate with ultraviolet light (25
0 mJ / cm ² ), and then peel the adhesive sheet from the surface of the adherend. For each adherend after peeling, determine the number of foreign matter of 0.15 μm or more remaining on the surface using a laser surface inspection device. It was measured and evaluated as follows. ○ ・ ・ ・ 4 or less △ ・ ・ ・ 5 to 29 × ・ ・ ・ 30 or more

(Non-corrosive) The pressure-sensitive adhesive sheet was stuck on a copper plate and left in a dark room at 60 ° C. and 65% RH for one week.
It was left for 1 hour under the conditions of 23 ° C. and 65% RH, and irradiated with ultraviolet rays (250 mJ / cm ^{2 with a} high-pressure mercury lamp).
The adhesive sheet was peeled off from the copper plate, and the peeled surface of the copper plate was visually compared with the blank copper plate, and evaluated as follows. ○: Same as blank copper plate surface △: Copper plate surface slightly discolored and slight corrosion was observed ×: Copper plate surface was significantly discolored and considerable corrosion was observed

Example 2 A removable pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group was changed as follows. The same evaluation as in Example 1 was performed.

[Acrylic pressure-sensitive adhesive containing ethylenically unsaturated group and acetoacetyl group (A)] In Example 1, 2-methacryloyloxyethyl isocyanate (a2) was changed to 11.5 parts and the side chain was changed to 11.5 parts. An ethylenically unsaturated group is added to 2-hydroxyethyl acrylate
Acrylic pressure-sensitive adhesive (A) solution (resin content 35%, viscosity 1800 mPa · s)
(25 ° C.)). The weight-average molecular weight of the acrylic pressure-sensitive adhesive (A) was 550,000, the number of ethylenically unsaturated groups was 4.6 per 10,000 weight-average molecular weight, and the content of acetoacetyl groups was 7.0% by weight. Was.

Example 3 [Acetoacetyl group-containing acrylic polymer (a1) having a functional group in the molecule] 75 parts of butyl acrylate, 2-
20 parts of hydroxyethyl acrylate, 5 parts of acetoacetylated 2-hydroxyethyl methacrylate used in Example 1 and 80 parts of ethyl acetate were charged, and after heating under reflux, azobisisobutyronitrile 0.1 part was used as a polymerization initiator.
After adding 3 parts at the reflux temperature of ethyl acetate, 0.07 parts of azobisisobutyronitrile and 5 parts of toluene were added, and the mixture was further reacted for 4 hours. A polymer (a1) solution (resin content 40%, viscosity 11,000 mPa · s (25 ° C.)) was obtained.

[Acrylic pressure-sensitive adhesive containing ethylenically unsaturated group and acetoacetyl group (A)] Dilauryl was added to 100 parts of the obtained acetoacetyl group-containing acrylic polymer (a1) solution (resin content: 40%). 0.004 part of di-n-butyltin acid, hydroquinone monoethyl ether 0.0
06 parts and 6.6 parts of 2-methacryloyloxyethyl isocyanate (a2) as a functional group-containing unsaturated compound were charged, reacted at 50 ° C. for 20 hours, finally diluted with toluene, and ethylenically unsaturated in the side chain. Adhesive (A) solution in which a group is added to 2-hydroxyethyl acrylate at 60 mol% (resin content 35%, viscosity 190
0 mPa · s (25 ° C.)).

The acrylic pressure-sensitive adhesive (A) has a weight average molecular weight of 560,000, the number of ethylenically unsaturated groups is 2.5 per 10,000 weight average molecular weight, and the content of acetoacetyl group is 4.3 weight. %Met. Using the acrylic pressure-sensitive adhesive (A) solution, a removable pressure-sensitive adhesive composition solution was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

Example 4 A peelable pressure-sensitive adhesive composition was prepared in the same manner as in Example 3, except that the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group was changed as follows. The same evaluation as in Example 1 was performed.

[Acrylic pressure-sensitive adhesive containing an ethylenically unsaturated group and an acetoacetyl group (A)] In Example 3, 2-methacryloyloxyethyl isocyanate (a2) was changed to 11.2 parts and the side chain was changed to An ethylenically unsaturated group is added to 2-hydroxyethyl acrylate
Acrylic pressure-sensitive adhesive (A) solution (resin content 35%, viscosity 1850 mPa · s)
(25 ° C.)). The weight-average molecular weight of the acrylic pressure-sensitive adhesive (A) was 570,000, the number of ethylenically unsaturated groups was 4.5 per 10,000, and the content of acetoacetyl groups was 3.1% by weight. Was.

Example 5 In Example 1, 1 part of 1-hydroxycyclohexyl phenyl ketone (B) (Irgacure 184, manufactured by Ciba-Geigy Japan) was added to 1 part of benzyl dimethyl ketal (Irgacure 651, manufactured by Ciba-Geigy Japan). Except having changed, it carried out similarly and obtained the removable pressure-sensitive adhesive composition, and performed the same evaluation as Example 1.

Example 6 In Example 1, a 55% solution of tolylene diisocyanate adduct of trimethylolpropane in ethyl acetate (C)
("Coronate L-55E", manufactured by Nippon Polyurethane Co.)
Was changed to 0.25 parts of a polyamide-based compound (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., "Corponyl N-3331"), and a removable pressure-sensitive adhesive composition was obtained. An evaluation was performed.

Comparative Example 1 100 parts of the acetoacetyl group-containing acrylic polymer (a1) solution (resin content: 40%) obtained in Example 1 was reacted without reacting 2-methacryloyloxyethyl isocyanate (a2). 1.14 parts of 1-hydroxycyclohexyl phenyl ketone (B) ("Irgacure 184", manufactured by Ciba-Geigy Japan) and a 55% ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane (manufactured by Nippon Polyurethanes, "Coronate L- 55
E ") 0.29 part was added and stirred to obtain a removable pressure-sensitive adhesive composition solution as a uniform solution. The same evaluation as in Example 1 was performed.

Comparative Example 2 80 parts of butyl acrylate, 20 parts of 2-hydroxyethyl methacrylate and 80 parts of ethyl acetate were charged, and after heating under reflux, 0.07 part of azobisisobutyronitrile was added as a polymerization initiator, and ethyl acetate was added. After reacting at the reflux temperature for 3 hours, azobisisobutyronitrile (0.07 part) and toluene (5 parts) were added, and the mixture was further reacted for 4 hours, diluted with toluene and diluted with an acrylic polymer solution (resin content 35%, viscosity 1500).
0 mPa · s (25 ° C.)), 100 parts of the acrylic polymer solution (resin content 35%) was added to dilaurate di-
0.004 part of n-butyltin, 0.006 part of hydroquinone monoethyl ether and 2-methacryloyloxyethyl isocyanate (a
2) Charge 7.6 parts, react at 50 ° C. for 20 hours,
Lastly, the mixture was diluted with toluene, and an acrylic pressure-sensitive adhesive solution in which an ethylenically unsaturated group was added to the side chain at 80 mol% with respect to 2-hydroxyethyl acrylate (resin content: 30%, viscosity: 2500 mPa · s (25 ° C.) ) Got.

The weight average molecular weight of this acrylic pressure-sensitive adhesive was 520,000, and the number of ethylenically unsaturated groups was 3.36 per 10,000 weight average molecular weight. Using the acrylic pressure-sensitive adhesive solution described above, a removable pressure-sensitive adhesive composition solution was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

Comparative Example 3 64 parts of butyl acrylate, 30 of methyl methacrylate
Parts, 1 part of acrylic acid, 5 parts of 2-hydroxyethyl methacrylate and 90 parts of ethyl acetate, and after heating under reflux, azobisisobutyronitrile 0.1 part was used as a polymerization initiator.
After adding 3 parts at the reflux temperature of ethyl acetate, 0.07 parts of azobisisobutyronitrile and 5 parts of toluene were added, and the mixture was further reacted for 4 hours, diluted with toluene and diluted with an acrylic polymer solution ( Resin content 35%, viscosity 14500mPa
S (25 ° C.)), and 0.004 part of di-n-butyltin dilaurate and 0.1 part of hydroquinone monoethyl ether were added to 100 parts of the acrylic polymer solution (resin content: 35%).
006 parts and 1.9 parts of 2-methacryloyloxyethyl isocyanate (a2) as a functional group-containing unsaturated compound were charged, reacted at 50 ° C. for 30 hours, finally diluted with toluene, and ethylenically unsaturated in the side chain. Pressure-sensitive adhesive solution (resin content 30%, viscosity 2800 m
Pa · s (25 ° C.)).

The weight average molecular weight of this acrylic pressure-sensitive adhesive was 490,000, and the number of ethylenically unsaturated groups was 0.78 per 10,000 weight average molecular weight. Using the acrylic pressure-sensitive adhesive solution described above, a removable pressure-sensitive adhesive composition solution was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

Comparative Example 4 64 parts of butyl acrylate, 30 of methyl methacrylate
Parts, 1 part of acrylic acid, 5 parts of 2-hydroxyethyl methacrylate and 90 parts of ethyl acetate, and after heating under reflux, azobisisobutyronitrile 0.1 part was used as a polymerization initiator.
After adding 3 parts at the reflux temperature of ethyl acetate, 0.07 parts of azobisisobutyronitrile and 5 parts of toluene were added, and the mixture was further reacted for 4 hours, diluted with toluene and diluted with an acrylic polymer solution ( Resin content 35%, viscosity 14500mPa
.S (25 ° C.)), and the following urethane acrylate 2 was added to 100 parts of the acrylic polymer solution (resin content: 35%).
5 parts, 1-hydroxycyclohexylphenyl ketone (B) (manufactured by Nippon Ciba Geigy, "Irgacure 18")
4 ") 0.85 part of a 55% solution of tolylene diisocyanate adduct of trimethylolpropane in ethyl acetate (C)
("Coronate L-55E", manufactured by Nippon Polyurethane Co.)
0.35 parts was added and stirred to obtain a removable pressure-sensitive adhesive composition solution as a uniform solution, and the same evaluation as in Example 1 was performed.

[Urethane acrylate] 17.5 parts of isophorone diisocyanate, 82.5 parts of dipentaerythritol pentaacrylate, 0.02 part of di-n-butyltin dilaurate, and 0.03 part of hydroquinone monoethyl ether were charged at 50 ° C. The reaction was carried out for 7 hours to obtain a urethane acrylate having a weight average molecular weight of 1300.

Comparative Example 5 100 parts of the acetoacetyl group-containing acrylic polymer (a1) solution (resin content: 40%) obtained in Example 1 was reacted without reacting 2-methacryloyloxyethyl isocyanate (a2). 25 parts of the urethane acrylate used in Comparative Example 4, 0.85 part of 1-hydroxycyclohexylphenyl ketone (B) (“Irgacure 184”, manufactured by Ciba-Geigy Japan), 55% acetic acid of tolylene diisocyanate adduct of trimethylolpropane Ethyl solution (manufactured by Nippon Polyurethanes, "Coronate L-55E")
0.35 parts was added and stirred to obtain a removable pressure-sensitive adhesive composition solution as a uniform solution, and the same evaluation as in Example 1 was performed.
Table 1 shows the evaluation results of the examples and the comparative examples.

[Table 1] Initial adhesive strength Durability Removability Stain resistance Non-corrosive(g / 25mm)   (g / 25mm)   Example 1 520 520 ○ 20 20 20 ○ ○ 〃 〃 2 810 820 〃 14 14 15 ○ ○ 〃 〃 3 505 515 ○ 20 20 20 ○ ○ 〃 ４ 4 750 770 ○ 15 15 15 ○ ○ 〃 ５ 5 500 510 ○ ○ 21 22 ○ ○ ○６ 6 550 565 ○ ○ 18 19 ○ ○ ○ Comparative Example 1 340 345 ○ ○ 150 160 △ △ ○ 〃 2 170 180 × × 13 12 ○ ○ ○ ３ 3 330 340 ○ ○ 60 65 ○ ○ × ４ 4 310 310 ○ ○ 20 22 △ △ ×５ 5 430 435 ○ ○ 12 13 △ △ ○

[0077]

The removable pressure-sensitive adhesive composition of the present invention comprises an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, a photopolymerization initiator (B) and a crosslinking agent (C). It is excellent in initial adhesive strength, durability under high temperature and re-peelability, and also shows excellent effects of stain resistance and non-corrosion after peeling, metal plate, glass plate ,
It is very useful as an adhesive used for an adhesive sheet for temporary surface protection or temporary adhesion such as a plastic plate or an adhesive sheet for fixing a semiconductor in a dicing process such as a semiconductor wafer.

Continued on the front page F-term (reference) 4J040 EB112 EB132 EC032 EC062 EF301 EF311 EG002 FA231 GA05 GA06 GA07 GA11 GA13 GA22 GA25 HB17 HB19 HC04 HC05 HC09 HC22 HC25 HD19 HD41 JA09 JB09 KA13 KA16 LA06 LA07 LA08 MA02 MA05 MA10 MB05 PA05

Claims (5)

[Claims] 1. Re-peeling characterized by comprising an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, a photopolymerization initiator (B) and a crosslinking agent (C). Type pressure-sensitive adhesive composition. 2. An acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, wherein the ethylenically unsaturated group accounts for 10,000 per weight average molecular weight of the acrylic pressure-sensitive adhesive (A). 2. The removable pressure-sensitive adhesive composition according to claim 1, wherein the number of the adhesive is 0.1 to 100. 3. An acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group, wherein the content of the acetoacetyl group in the acrylic pressure-sensitive adhesive (A) is 0.01 to 0.01. 3. The removable pressure-sensitive adhesive composition according to claim 1, wherein the content is 40% by weight. 4. The content of the photopolymerization initiator (B) is 0.1 to 10 with respect to 100 parts by weight of an acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group.
The removable pressure-sensitive adhesive composition according to any one of claims 1 to 3, which is part by weight. 5. The content of the crosslinking agent (C) is 100 parts by weight of the total of the acrylic pressure-sensitive adhesive (A) containing an ethylenically unsaturated group and an acetoacetyl group and the photopolymerization initiator (B). The removable pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the content is 0.005 to 10 parts by weight based on the weight of the pressure-sensitive adhesive composition.