JP2003027026A - Re-releasable water-dispersed pressure-sensitive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack re-releasable water-dispersed pressure-sensitive adhesive usable for self-adhesive labels and sheets and which is excellent in self-adhesive properties and easily released from the surface of an adherend even after left at a high temperature for long hours after stuck to the adherend. SOLUTION: The re-releasable water-disposed pressure-sensitive adhesive comprises (A) 100 pts.wt. of solids content of a water-based dispersion comprising a copolymer obtained by copolymerizing a monomer mixture comprising (a) an alkyl (meth)acrylate monomer bearing a 4-12C alkyl group as a main component, (b) 0.02-5 wt.% of a carbonyl group-containing unsaturated monomer and (c) 0.1-40 wt.% of an unsaturated monomer copolymerizable with the alkyl (meth)acrylate monomer other than the carbonyl group-containing unsaturated monomer, the monomers (a), (b) and (c) adding up to 100 wt.%, and incorporated therewith, (B) 0.05-5 moles, based on 1 mole of the carbonyl group in the component (A), of a hydrazine derivative bearing in the molecule at least two hydrazine groups, and (c) 0.2-10 pts.wt. of at least one water-retaining agent selected among polyhydric alcohols.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention can be used as an adhesive for pressure-sensitive adhesive labels, tapes, sheets and surface protective films, has excellent adhesiveness, and is adhered to various adherends (metal plates, plastic plates, etc.). The present invention relates to a water-dispersible pressure-sensitive adhesive for re-peeling, which can be easily peeled even after being left at a high temperature for a long time.

[0002]

2. Description of the Related Art Adhesive labels are used for price labels, process control labels, courier address labels, etc.
After sticking to the adherend for these applications, after a certain period of time,
It is often peeled off from the adherend. At this time, a part of the pressure-sensitive adhesive often remains on the adherend. In addition, when the base material is paper, the strength of the paper is weak, so that the paper often breaks and becomes difficult to peel from the adherend. Removable pressure-sensitive adhesives have been conventionally proposed so that they can be easily peeled from an adherend without such a problem.

Japanese Patent Publication No. 5-075034 discloses a water-based pressure-sensitive adhesive characterized in that a polyglycidyl compound is added to an aqueous copolymer emulsion having a specific monomer composition, molecular weight, glass transition temperature and particle size. Has been done. However, in this pressure-sensitive adhesive, when a polyglycidyl compound is added to the emulsion, the interparticle cross-linking reaction of the emulsion proceeds and the viscosity increases or gelation occurs,
There is a problem of pot life that the polyglycidyl compound must be used within several hours after compounding.

In Japanese Patent Publication No. 58-22492, a monomer containing an acrylic acid alkyl ester, an ethylenically unsaturated carboxylic acid and a monomer having two vinyl groups are emulsion-copolymerized. A pressure sensitive adhesive in which monovalent metal ions are added to the resulting copolymer emulsion is disclosed. Since this emulsion uses ionic cross-linking, it is possible to make one liquefaction without the need to add a cross-linking agent immediately before use, but if it is stored for a long time after pasting, the tackiness increases and the removability decreases. is there.

JP-A-6-158010 discloses a resin obtained by emulsion polymerization of a monomer mixture containing 0.1 to 5% by weight of a carbonyl group-containing unsaturated monomer using a chain transfer agent. An aqueous adhesive composition comprising an aqueous dispersion and a hydrazine derivative having at least two hydrazino groups in the molecule is disclosed. This composition can be made into one liquefaction because stable performance can be obtained even after blending the hydrazine derivative, but the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive has removability at the initial stage of application, but at high temperature for a long time. When stored, there is a problem that the adhesive strength increases and the removability decreases.

[0006]

An object of the present invention is to provide an adhesive label which has excellent adhesiveness and can be easily peeled off from the surface of an adherend after being attached to the adherend and left at a high temperature for a long time. It is intended to provide a water-dispersible pressure-sensitive adhesive for one-component type re-peelable that can be used for various kinds.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors in order to achieve the above-mentioned object, the inventors have found that an aqueous dispersion comprising a carbonyl group-containing acrylic resin composition has 2 By adding a hydrazine derivative having individual hydrazino groups and a specific humectant, it was found that the hydrazine derivative can be easily peeled from the adherend surface even after being left at high temperature for a long time after application, and to complete the present invention. I arrived.

That is, (A) (a) a (meth) acrylic acid alkyl ester monomer having an alkyl group having 4 to 12 carbon atoms as a main component, and (b) a carbonyl group-containing unsaturated monomer are copolymerized. To an aqueous dispersion composed of the copolymer
A water-dispersible pressure-sensitive adhesive for re-peeling, comprising (B) a hydrazine derivative having at least two hydrazino groups in the molecule and (C) at least one moisturizer selected from polyhydric alcohols. , Preferably (A)
(A) Alkyl group having 4 to 12 carbon atoms (meth) acrylic acid alkyl ester monomer, (b) 0.02 to 5% by weight of carbonyl group-containing unsaturated monomer, (c) (meth) Unsaturated monomer other than carbonyl group-containing unsaturated monomer copolymerizable with acrylic acid alkyl ester monomer Unsaturated monomer 0.1-40% by weight "(a) (b) and (c)" 100% by weight of the solid content of the aqueous dispersion obtained by copolymerizing the monomer mixture of 100% by weight of the monomer mixture,
(B) The hydrazine derivative having at least two hydrazino groups in the molecule is selected from 0.05 to 5 mol per 1 mol of the carbonyl group in the component (A), and (C) polyhydric alcohols. A removable water-dispersible pressure-sensitive adhesive containing 0.2 to 10 parts by weight of one or more moisturizers.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The constitution of the present invention will be described in detail below. The (a) alkyl group used in the present invention has 4 carbon atoms.
Specific examples of the (meth) acrylic acid alkyl ester monomers of to 12 include butyl (meth) acrylate, (meth)
2-ethylhexyl acrylate, isononyl (meth) acrylate, isooctyl (meth) acrylate, (meth)
Examples thereof include lauryl acrylate and the like, and one or more selected from these groups can be used. The amount used is preferably 55 to 99.88% by weight based on the total amount of the monomers. It is more preferably 70 to 99.88% by weight, and even more preferably 90 to 99.88% by weight. If the amount used is less than 55% by weight, the adhesion to the substrate will be reduced.

Specific examples of the (b) carbonyl group-containing unsaturated monomer used in the present invention include acrolein, diacetone acrylamide and formyl styrene, preferably vinyl alkyl ketone having 4 to 7 carbon atoms,
For example, vinyl methyl ketone, vinyl ethyl ketone, vinyl isobutyl ketone, etc., acetoacetoxyethyl (meth) acrylate, diacetone (meth) acrylate,
Acetonyl acrylate, 2-hydroxypropyl acrylate-acetyl acetate, butanediol-1,
4-acrylate-acetyl acetate and the like,
One or more selected from these groups can be used. The amount used is preferably 0.02 to 5% by weight with respect to the total amount of the monomers. If the amount used is outside this range, either the adhesive strength or the removability will deteriorate.

It is also possible to use an unsaturated monomer other than the carbonyl group-containing unsaturated monomer copolymerizable with the (c) (meth) acrylic acid alkyl ester monomer. For example, an alkyl group such as methyl methacrylate, ethyl acrylate, or isopropyl acrylate has a carbon number of 1 to 3 (meth) acrylic acid alkyl ester, tridecyl methacrylate, stearyl acrylate, or another alkyl group having a carbon number of 13 to 18- (meth) acrylic acid alkyl ester, (meth) acrylic acid hydroxyalkyl, glycerin di (meth) acrylate and other hydroxyl group-containing monomers, maleic anhydride, (meth) acrylic acid, itaconic acid and other carboxyl groups Contained monomers, vinyl acetate, styrene, (meth) acrylonitrile, N-vinylpyrrolidone, (meth) acryloylmorpholine, cyclohexylmaleimide, isopropylmaleimide, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) Glycidyl acrylate, etc. The recited may be used one or more from these groups. The amount used is 0.1 to 40% by weight based on the total amount of the monomers. If the amount used is less than 0.1% by weight, the stability during the polymerization reaction tends to deteriorate, and if it exceeds 40% by weight, the adhesion becomes poor.

The aqueous dispersion (A) of the present invention can be obtained by a known suspension polymerization method or emulsion polymerization method. The emulsion polymerization method is preferred. The reaction method is not particularly limited in the present invention whether it is a one-step emulsion polymerization method or a multi-step emulsion polymerization method.

2,2'-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator that can be used when the aqueous dispersion (A) of the present invention is prepared by emulsion polymerization.
Azo compounds such as 2,2′-azobis (2-amidinopropane) dihydrochloride, persulfates such as potassium persulfate and ammonium persulfate, benzoylperoxide, t-
Peroxides such as butyl hydroperoxide and hydrogen peroxide can be used. A redox initiator composed of a combination of persulfate and sodium bisulfite, a combination of peroxide and sodium ascorbate, etc. can also be used. Usually, these polymerization initiators may be added in a predetermined amount at each stage of emulsion polymerization so that the polymerization reaction is carried out.

When the aqueous dispersion (A) of the present invention is prepared by emulsion polymerization, an appropriate amount of anionic or nonionic emulsifier is used in order to ensure polymerization stability. Specific examples of the anionic emulsifier include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate and the like. Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers. Further, a radical-polymerizable reactive emulsifier having a propenyl group, an acryloyl group or the like introduced therein can also be used. These emulsifiers can be used alone or in combination.

The hydrazine derivative having at least two hydrazino groups in the molecule (B) used in the present invention is 2
A dicarboxylic acid dihydrazide which is a dehydration condensation product of a dicarboxylic acid having 10 to 10, preferably 4 to 6 carbon atoms and hydrazine, for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide. , Sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, valine dihydrazide, etc .; aliphatic water-soluble dihydrazines having 2 to 4 carbon atoms, such as ethylene-1,2-dihydrazine, propylene-1 , 3-dihydrazine, butylene-1,4-dihydrazine and the like, and at least one or more selected from these groups can be used.

The proportion of the hydrazine derivative used in the present invention is 0.05 to 5 moles, preferably 0.2 to 4 moles of hydrazino group per mole of carbonyl group in component (A).
It is a mole. Outside of these ranges, properties such as adhesive strength, removability, and adhesion to the base material will deteriorate.

As the effect of the moisturizing agent (C) used in the present invention, the reaction of the carbonyl group and the hydrazino group proceeds after water is evaporated, but the presence of the moisturizing agent can adjust the reaction rate. It is considered that this acts to increase the adhesion to the base material.

The moisturizing agent (C) used in the present invention includes:
At least one selected from polyhydric alcohols can be used. In particular, among polyhydric alcohols, use of dihydric to polyhydric alcohols which are liquid at room temperature, polyoxyalkylenes, glycol ethers of polyoxyalkylenes, polyoxyalkylene adducts of alkylamines, etc. Is preferred. Specifically, ethylene glycol, polyalkylene glycol having an average molecular weight of 1000 or less, glycerin, polyglycerin (for example, diglycerin, hexaglycerin, hexagcerine,
Decaglycerin), glycerin ethylene oxide adduct, glycerin propylene oxide adduct, trimethylolpropane propylene oxide adduct, sorbitol propylene oxide adduct, ethylenediamine propylene oxide adduct, ethylene oxide / propylene oxide / ethylene oxide block, alkylamine ethylene Oxide adducts and the like,
At least one selected from these groups can be used. More preferred are ethylene glycol, polyethylene glycol having an average molecular weight of 1,000 or less, glycerin, and polyglycerin. The moisturizing agent is used in an amount of 0.2 based on 100 parts by weight of the solid content of the (A) aqueous dispersion.
-10 parts by weight is preferable. If the amount used is less than 0.2 parts by weight, the adhesion to the substrate will decrease, and if it exceeds 10 parts by weight, the cohesive force will decrease and the removability will decrease.

The water-dispersible pressure-sensitive adhesive for re-peeling of the present invention contains various additives, such as tackifying resins and cross-linkers, in the water-dispersed liquid, if necessary, within a range that does not affect the effects of the present invention. Agents, plasticizers, softeners, fillers, pigments, dyes, antioxidants, thickeners, defoamers, preservatives and the like can be added.

The water-dispersible pressure-sensitive adhesive for re-peeling of the present invention is directly coated on an appropriate support such as a plastic film, paper or metal foil according to a conventional method for producing pressure-sensitive adhesive sheets. The pressure-sensitive adhesive for re-peeling is formed into a sheet-like or tape-like form by being dried or coated on a separator and dried and then transferred onto an appropriate support. It can be an adhesive sheet.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is not limited to the following examples. Further, in the following, all parts or% mean parts by weight or% by weight.

Example 1 A reactor equipped with a thermometer, a stirrer, a dripping device, a reflux cooling pipe and a nitrogen introducing pipe was weighed with 28 parts of ion-exchanged water, nitrogen was sealed therein, and the internal temperature was raised to 80 ° C. Then, while maintaining the temperature, 2 parts of an aqueous solution of 10% ammonium persulfate was added, and immediately, a separately prepared monomer mixture of 96 parts of 2-ethylhexyl acrylate, 2 parts of acrylic acid and 2 parts of diacetone acrylamide was added to A monomer emulsion obtained by mixing 4 parts of sodium oxyethylene alkylphenyl ether sodium sulfate (trade name: Rebenol WZ manufactured by Kao Co., Ltd.) and 56 parts of ion-exchanged water was continuously added dropwise for 4 hours to perform emulsion polymerization. In parallel, 4 parts of a 5% aqueous ammonium persulfate solution was added dropwise. After completion of dropping, the mixture was aged at 80 ° C. for 4 hours and then cooled to room temperature. Neutralize with ammonia water and adjust the solid content with water to obtain a solid content of 50% and a viscosity of 50 mP.
An aqueous dispersion having an pH of 8.0 was obtained. To the water dispersion, 0.5 part of glycerin was added as a moisturizer to 100 parts of the solid content of the water dispersion, and a polyacrylic acid thickener (trade name ASE-60 manufactured by Rohm and Haas Co.) was added. Then, the viscosity was increased to 10,000 mPa · s (B-type viscometer), and 10 parts of an aqueous solution of adipic dihydrazide having a concentration of 10% was added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. . The adhesive was applied to release paper so as to have a thickness of 25 μm after drying, dried at 100 ° C. for 1 minute, and transferred to high-quality paper (64 g / m ² ) at 23 ° C. 65
After standing in an atmosphere of% RH for 7 days, a removable adhesive label was obtained. The test results were good in all of adhesive strength, removability and leaving stability. The results are shown in Table 1.

Examples 2 to 5 Examples 2, 3, 4 and 5 were carried out except that the kinds and amounts of the monomers were changed as shown in Table 1 and the kinds and amounts of the moisturizer and the cross-linking agent were changed. A water-dispersible pressure-sensitive adhesive was obtained in exactly the same manner as in Example 1 to obtain a removable pressure-sensitive adhesive label. The test result is adhesive strength,
The removability and the leaving stability were all good. The results are shown in Table 1.

Example 6 Separately, 48.8 parts of 2-ethylhexyl acrylate, 1 part of acrylic acid, 0.2 part of diacetone acrylamide as a monomer mixed emulsion for phase a sodium polyoxyethylene alkylphenyl ether sulfate (Kao ( 2 parts of Rebenol WZ manufactured by Co., Ltd. and 28 parts of ion-exchanged water are mixed to prepare an emulsified monomer emulsion. Separately, 2-ethylhexyl acrylate 48 as a b-phase monomer mixed emulsion
Parts, acrylic acid 1 part, diacetone acrylamide 1 part
A monomer emulsion prepared by mixing 2 parts of sodium polyoxyethylene alkylphenyl ether sulfate (Lebenol WZ manufactured by Kao Corporation) and 28 parts of ion-exchanged water to prepare an emulsion is prepared. A reactor equipped with a thermometer, a stirrer, a dropping device, a reflux cooling pipe and a nitrogen introducing pipe was charged with 28 parts of ion-exchanged water and nitrogen to raise the internal temperature to 80 ° C., and while maintaining the temperature, 10 2 parts of an aqueous solution of ammonium persulfate having a concentration of 5% was immediately added, and immediately, a monomer emulsion for phase a was continuously added dropwise over 2 hours.
Emulsion polymerization was carried out while dropping parts. Immediately after the dropping of the a-phase monomer emulsion, the b-phase monomer emulsion is continuously dropped for 2 hours, and similarly, 2 parts of a 5% ammonium persulfate aqueous solution is dropped in parallel. The emulsion was polymerized. After completion of dropping, the mixture was aged for 4 hours while maintaining the internal temperature at 80 ° C. Then, it cooled to room temperature. Neutralize with ammonia water, adjust the solid content with water to obtain a solid content of 50%, viscosity of 40 mPa · s, p
An aqueous dispersion having a two-layer structure of H8.0 was obtained. To the aqueous dispersion, 3 parts of ethylene glycol as a moisturizing agent and 3 parts of PEG-600 (polyethylene glycol with an average molecular weight of 600 manufactured by Asahi Denka Co., Ltd.) were added to 100 parts of the solid content of the aqueous dispersion to obtain a polyacryl. An acid-based thickener (trade name: ASE-60, manufactured by Rohm and Haas Co.) was added to thicken the viscosity to 10,000 mPa · s (B type viscometer), and 10% adipic acid dihydrazide aqueous solution was further added.
Part of the mixture was added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. A re-peelable pressure-sensitive adhesive label was obtained in the same manner as in Example 1. The test results were good in all of adhesive strength, removability and leaving stability. The results are shown in Table 1.

Comparative Example 1 A reactor equipped with a thermometer, a stirrer, a dropping device, a reflux cooling pipe and a nitrogen introducing pipe was charged with 28 parts of ion-exchanged water and nitrogen to raise the internal temperature to 80 ° C. While keeping 1
Immediately after the addition of 2 parts of 0% aqueous ammonium persulfate solution, 2-ethylhexyl acrylate 98 was prepared separately.
Parts, acrylic acid 2 parts, sodium polyoxyethylene alkylphenyl ether sulfate (trade name Rebenol WZ manufactured by Kao Corporation) 4 parts, and ion-exchanged water 56 parts were mixed to emulsify the monomer emulsion continuously for 4 hours. Dripping,
In parallel, 4 parts of a 10% aqueous ammonium persulfate solution was added dropwise to carry out emulsion polymerization. After completion of dropping, the mixture was aged at 80 ° C. for 4 hours and then cooled to room temperature. Neutralize with ammonia water and adjust the solid content with water to obtain a solid content of 50% and a viscosity of 60 mPa · s.
To obtain an aqueous dispersion. A polyacrylic acid-based thickener (Rohm & Haas Co., trade name ASE-60) was added to the aqueous dispersion to thicken it to 10,000 mPa · s (B-type viscometer), and further the aqueous dispersion 10% for 100 parts of solid content
A water-dispersible pressure-sensitive adhesive for re-peeling was prepared by adding 10 parts of an adipic acid dihydrazide aqueous solution having a concentration and mixing them well. An adhesive label for re-peeling was obtained in the same manner as in Example 1. The test results showed that the adhesive strength and leaving stability were good, but the removability was poor. The results are shown in Table 2.

Comparative Example 2 Comparative Example 2 is an example in which the amount of diacetone acrylamide which is the carbonyl group-containing unsaturated monomer of Example 2 was outside the range of the present invention. An aqueous dispersion liquid was obtained in the same manner as in Example 2. A moisturizer and a cross-linking agent were added to the aqueous dispersion in the same manner as in Example 2 to obtain an adhesive label for re-peeling and the adhesive label was tested. The test results showed that the adhesive strength and leaving stability were good, but the removability was poor. The results are shown in Table 2.

Comparative Example 3 In Comparative Example 3, an aqueous dispersion was obtained in exactly the same manner as in Example 6. This is an example in which a humectant was added to the aqueous dispersion outside the scope of the present invention. A cross-linking agent was added in the same manner as in Example 6 to obtain a removable pressure-sensitive adhesive label and the pressure-sensitive adhesive label was tested. The test results showed that the adhesive strength and leaving stability were good, but the removability was poor. The results are shown in Table 2.

[0028]

[Table 1]

[0029]

[Table 2]

The number of moles shown in Tables 1 and 2 is the number of moles of the hydrazine derivative with respect to 1 mole of the carbonyl group in the component (A).

In Tables 1 and 2, the types of monomers, moisturizers and crosslinking agents are indicated by the following abbreviations. Monomer 2EHA: 2-Ethylhexyl acrylate BA: Butyl acrylate MMA: Methyl methacrylate AAc: Acrylic acid DAAM: Diacetone acrylamide AAEM: Acetoacetoxyethyl methacrylate moisturizer PEG-600: Polyethylene glycol having an average molecular weight of 600 (manufactured by Asahi Denka Co., Ltd. ) G-400: Glycerin PO adduct having an average molecular weight of 400 (manufactured by Asahi Denka Co., Ltd.) Crosslinking agent ADH: Adipic acid dihydrazide VDH: Valine dihydrazide (manufactured by Ajinomoto Co., Inc.)

Test method 1. Test sample The water-dispersible pressure-sensitive adhesive for re-peeling thus obtained was applied to release paper so as to have a thickness of 25 μm and dried at 100 ° C. for 1 minute, and then fine paper (64 g / m 2 ² ) Transfer to 23 ℃ 6
After being left in an atmosphere of 5% RH for 7 days, an adhesive label for re-peeling was obtained.

2. Test method For each removable pressure-sensitive adhesive label, the adhesive strength, the removable property and the adhesion to the substrate were examined by the following methods. Adhesion According to JIS Z 0237 peel off 180 ° Adhesion, a test adhesive label was cut and adhered to a stainless steel plate and a polypropylene plate with a width of 25 mm according to JIS Z 0237 measurement, and then 1 reciprocating pressure was applied with a 2 Kg roller, then at 23 ° C, 65 ° C. After standing in% RH for 20 minutes, the adhesive strength was measured at that temperature at a peeling speed of 300 mm / min with a Tensilon tensile tester. The unit of measurement is N / 25 mm. Cut the adhesive label for removability test into 25 mm wide polystyrene plates,
Laminated on polypropylene plate, PVC plate at room temperature, 40 ℃
After leaving it in a constant temperature bath for 30 days, take it out, leave it in an atmosphere of 23 ° C. and 65% RH for 1 day or more, peel it off with a tensile tester at a peeling speed of 300 mm / min, and visually check the condition of the adherend surface after peeling. It was judged. ⊚: Can be peeled off neatly without adhesive residue or paper breakage. ◯: 50% or more can be peeled off cleanly, but there is paper tear at the edge. Δ: Adhesive residue and paper tear are partially present. X: Adhesive residue or paper tear is present on the entire surface. Storage stability The water-dispersible pressure-sensitive adhesive for re-peeling of the present invention was used at 25 ° C. for 30 days.
The liquid material was observed after being left for one day. ○: No change from the initial stage △: Viscosity slightly increased ×: Gelation

[0034]

INDUSTRIAL APPLICABILITY The present invention provides an aqueous dispersion of a carbonyl group-containing acrylic copolymer, a hydrazine derivative having at least two hydrazino groups in the molecule, and a water-retaining agent selected from polyhydric alcohols. By containing the agent, the pressure-sensitive adhesive label / sheet has excellent adhesiveness and can be easily peeled off from the surface of the adherend even after being left on the adherend for a long time at high temperature after being adhered to the adherend. It is useful as a pressure-sensitive adhesive for re-peeling used for the above.

Claims (2)

[Claims] 1. The carbon number of (A) (a) alkyl group is 4 to
An aqueous dispersion containing 12 (meth) acrylic acid alkyl ester monomers as a main component and (b) a carbonyl group-containing unsaturated monomer is copolymerized, and at least 2 in the molecule (B).
Water-dispersible pressure-sensitive adhesive for re-peeling, which comprises a hydrazine derivative having one hydrazino group and at least one moisturizer selected from (C) polyhydric alcohols. 2. The carbon number of (A) (a) alkyl group is 4 to.
12 (meth) acrylic acid alkyl ester monomers,
(B) 0.02 to 5% by weight of a carbonyl group-containing unsaturated monomer, (c) an unsaturated monomer other than the carbonyl group-containing unsaturated monomer copolymerizable with the (meth) acrylic acid alkyl ester monomer Monomer 0.1-40% by weight Solid of aqueous dispersion obtained by copolymerizing monomer mixture of "(a) (b) and (c) monomer is 100% by weight" The amount of the hydrazine derivative having at least two hydrazino groups in the molecule (B) is 0.05 to 5 mol per 1 mol of the carbonyl group in the component (A), and The water-dispersible pressure-sensitive adhesive for re-peeling according to claim 1, containing 0.2 to 10 parts by weight of at least one moisturizer selected from polyhydric alcohols.