JPH11256125A - Water-dispersion type pressure sensitive adhesive for re-peeling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-dispersion type pressure sensitive adhesive having excellent backface fixability and readily peelable from the surface of a material to be adhered without inducing cohesive failure even after pasting on a material to be adhered and exposing in a high temperature atmosphere. SOLUTION: This adhesive is composed of a two-phase constitution of polymer particles emulsifying and dispersing into water comprising (A) a phase composed of a copolymer of a monomer mixture containing an alkyl (meth) acrylate having a 4-12C alkyl group as a main component and a carboxylic group-containing monomer and (B) a phase of a polymer of an alkyl (meth) acrylate having a 4-12C alkyl group as a main component, a carboxylic group- containing monomer and a monomer not containing a functional monomer reacting with carboxylic group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a removable water-dispersible pressure-sensitive adhesive for use in pressure-sensitive adhesive sheets for masking.

[0002]

2. Description of the Related Art Pressure-sensitive adhesive sheets for masking (sheets)
(Tape, tape, etc.) is that the adhesive strength does not increase by heating, glue remains on the adherend after peeling, sheet (tape) marks,
The absence of discoloration of the adherend is an important required characteristic.

In order to improve these characteristics, for example, Japanese Patent Application Laid-Open No. Hei 6-346038 discloses that a specific monomer and emulsifier composition can be applied to various adherends in a wide temperature range from a low temperature to a high temperature. A water-based re-peelable pressure-sensitive adhesive exhibiting excellent re-peelability is disclosed. However, in the method described in the example of this publication,
When peeled immediately after heating, there was a problem of cohesive failure.

Japanese Patent Application Laid-Open No. Hei 6-322345 discloses that various types of adherends exhibit good removability by performing polymerization using a redox polymerization initiator under a specific oxygen concentration condition. A pressure-sensitive adhesive is disclosed. However, this pressure-sensitive adhesive has a problem that its fixability to its own back surface is poor.

When a wide masking area is required for masking applications, a plurality of pressure-sensitive adhesive sheets may be overlapped and spliced. in this case,
Since another pressure-sensitive adhesive sheet is stacked on a part of the back surface of the pressure-sensitive adhesive sheet previously attached to the adherend, problems such as intrusion of paint from the overlapping area are prevented. And adhesiveness in this region is strongly required. In other words, the pressure-sensitive adhesive sheet that was previously attached to the adherend
It is required that the pressure-sensitive adhesive sheets to be stacked on the back surface of the papers have high fixability, that is, high self-backing property.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and has excellent self-rear surface fixing properties and does not cause cohesive failure even after being exposed to a high-temperature atmosphere after being attached to an adherend. An object of the present invention is to provide a water-dispersible pressure-sensitive adhesive for re-peeling, which is useful as a pressure-sensitive adhesive sheet for masking that can be easily peeled off from the surface of an adherend.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that when emulsion polymerization of an acrylic monomer is carried out, a two-phase composition having different monomer compositions is used. To form coalesced particles, or 2
By producing and blending seed polymer particles, one containing a carboxyl group-containing monomer and the other reacting with a carboxyl group-containing monomer and a carboxyl group, particularly as the different monomer composition described above. By having a structure that does not contain a functional monomer, it has excellent self-retaining property and heat resistance, and causes cohesive failure even after being exposed to a high-temperature atmosphere after being attached to an adherend. The present inventors have found that pressure-sensitive adhesive sheets for masking that can be easily peeled off from the surface of an adherend can be produced without any need, and have completed the present invention.

That is, according to the present invention, the polymer particles emulsified and dispersed in water are: A) a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms as a main component, and a carboxyl group-containing monomer; And B) an alkyl group having 4 to 12 carbon atoms.
(Meth) acrylic acid alkyl ester as a main component,
And a two-phase structure comprising a phase of a polymer of a monomer containing a carboxyl group-containing monomer and a functional monomer that does not react with a carboxyl group. The pressure-sensitive adhesive (Claim 1), especially 50 to 90% by weight of the A phase constituting the polymer particles and 50 to 1% by weight of the B phase.
The present invention relates to the water-dispersible pressure-sensitive adhesive for re-peeling having the above constitution, which is 0% by weight (claim 2).

Further, according to the present invention, there is provided a polymer particle emulsified and dispersed in water comprising: a) a (meth) acrylic acid alkyl ester having an alkyl group having 4 to 12 carbon atoms as a main component; And b) a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group as a main component, and a carboxyl group-containing monomer and a carboxyl group. 2. A water-dispersible pressure-sensitive adhesive for re-peeling, comprising two types of polymer particles comprising a polymer particle of a monomer not containing a reactive functional monomer. ), Especially 50 to 90% by weight of the a particles constituting the polymer particles;
The present invention relates to the water-dispersible pressure-sensitive adhesive for re-peeling of the above constitution, wherein the b particles are 50 to 10% by weight (claim 4).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION One of the water-dispersible pressure-sensitive adhesives for re-peeling according to the present invention comprises polymer particles emulsified and dispersed in water.
A) a phase comprising a copolymer of a monomer mixture containing (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as a main component and containing a carboxyl group-containing monomer; and B) an alkyl group. Consisting of a polymer of a monomer having an alkyl (meth) acrylate having 4 to 12 carbon atoms as a main component and not containing a carboxyl group-containing monomer and a functional monomer that reacts with a carboxyl group. In a two-phase configuration. Here, in order to obtain good removability, the phase A constituting the polymer particles is 50 to 90% by weight, preferably 60 to 80% by weight, and the phase B is 50 to 90% by weight.
The content is 10% by weight, preferably 40 to 20% by weight.

In the monomer mixture constituting the phase A, examples of the alkyl (meth) acrylate having an alkyl group of 4 to 12 carbon atoms include butyl (meth) acrylate and 2- (meth) acrylate. Examples include ethylhexyl, isononyl (meth) acrylate, isooctyl (meth) acrylate, and lauryl (meth) acrylate. Examples of the carboxyl group-containing monomer include maleic anhydride, (meth) acrylic acid, and itaconic acid.

In addition to these components, alkyl (meth) acrylates having an alkyl group having 1 to 3 carbon atoms, such as methyl methacrylate, ethyl acrylate and isopropyl acrylate, tridecyl methacrylate, stearyl (meth) acrylate Such as an alkyl group having 13 to 1 carbon atoms
8, hydroxyalkyl (meth) acrylates, hydroxyalkyl (meth) acrylates, hydroxyl-containing monomers such as glycerin di (meth) acrylate, vinyl acetate, styrene, (meth) acrylonitrile, N-vinylpyrrolidone, (Meth) acryloylmorpholine, cyclohexylmaleimide, isopropylmaleimide, (meth) acrylamide, N, N-dimethyl (meth) acrylamide,
Glycidyl (meth) acrylate may be used.

In the monomer mixture constituting the phase A, the alkyl (meth) acrylate having 4 to 12 carbon atoms in the alkyl group, the carboxyl group-containing monomer and the other monomers are copolymerized. The glass transition point of the coalescence is usually −
Each usage amount is determined so as to be 20 ° C. or lower. The alkyl (meth) acrylate having 4 to 12 carbon atoms in the alkyl group is used as a main component in a proportion of 50% by weight or more of all monomers, and the carboxyl group-containing monomer is used as a whole monomer. It is used at a ratio of 0.5 to 5% by weight in the body. Outside these ranges, good results are unlikely to be obtained in any of the properties such as pressure-sensitive adhesiveness, self-retaining property and removability (heat resistance).

In the monomer constituting the phase B, the alkyl (meth) acrylate having an alkyl group having 4 to 12 carbon atoms may be an alkyl (meth) acrylate having 4 to 12 carbon atoms in the phase A. The same ones as the alkyl (meth) acrylate can be used, and they are used as a main component in a proportion of 50% by weight or more of all monomers. Other monomers may be used together with this main component, but a carboxyl group-containing monomer and a functional monomer that reacts with a carboxyl group cannot be used together. If these are used together, a problem is likely to occur in removability (heat resistance), and it is impossible to achieve both self-rear surface fixability and removability.

Examples of the carboxyl group-containing monomer which cannot be used in combination include maleic anhydride, (meth) acrylic acid, and itaconic acid. Examples of the functional monomer that reacts with a carboxyl group that cannot be used in combination include hydroxyalkyl (meth) acrylate and glycerin dimethacrylate.
Hydroxyl-containing monomers such as N-vinylpyrrolidone,
(Meth) acryloylmorpholine, cyclohexylmaleimide, isopropylmaleimide, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, glycidyl (meth) acrylate, and the like.

The monomers which can be used in combination include alkyl (meth) acrylates having an alkyl group having 1 to 3 carbon atoms, such as methyl methacrylate, ethyl acrylate and isopropyl acrylate, tridecyl methacrylate, and (meth) The alkyl group such as stearyl acrylate has 13 to 1 carbon atoms.
And (8) alkyl (meth) acrylate, vinyl acetate, styrene, (meth) acrylonitrile and the like.
These are used in such an amount that the glass transition point of the polymer is usually -20 ° C or lower.

In the present invention, usually, first, the monomer mixture constituting the phase A is emulsion-polymerized, and then the monomer constituting the phase B is added to the polymerization system and emulsion-polymerized. By a two-stage polymerization method, two phases of the above-mentioned phase A and phase B
A water-dispersible pressure-sensitive adhesive for re-peeling comprising an aqueous dispersion in which polymer particles having a phase constitution are emulsified and dispersed is obtained. Here, the monomer mixture constituting the A phase and the monomer constituting the B phase are mixed with each other so that the weight ratio of the A phase and the B phase is within the above range. The body mixture is used in a proportion of 50 to 90% by weight, preferably 60 to 80% by weight, and the monomer constituting the B phase is used in a proportion of 50 to 10% by weight, preferably 40 to 20% by weight.

In the above emulsion polymerization, azo-based compounds such as 2,2'-azobis (2-methylpropionamidine) disulfate and 2,2'-azobis (2-amidinopropane) dihydrochloride are used as polymerization initiators. Persulfates such as potassium persulfate and ammonium persulfate; peroxides such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; combinations of persulfate and sodium bisulfite; and peroxide and ascorbic acid A redox initiator consisting of a combination with sodium or the like is used. Usually, a predetermined amount of these polymerization initiators may be added at each stage of the emulsion polymerization so as to cause the polymerization reaction.

In the above emulsion polymerization, an appropriate amount of an anionic or nonionic emulsifier is used in order to secure polymerization stability. Examples of the anionic type include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, and sodium polyoxyethylene alkyl phenyl ether sulfate. Examples thereof include an alkyl ether and a polyoxyethylene alkylphenyl ether. In both anionic and nonionic types, a radically polymerizable emulsifier having a propenyl group or the like may be used.

Another one of the water-dispersible pressure-sensitive adhesives for re-peeling according to the present invention comprises a) polymer particles which are emulsified and dispersed in water;
Particles composed of a copolymer of a monomer mixture containing a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as a main component and a carboxyl group-containing monomer,
b) The weight of a monomer containing an alkyl (meth) acrylate having 4 to 12 carbon atoms in the alkyl group as a main component and not containing a carboxyl group-containing monomer and a functional monomer that reacts with the carboxyl group. It is composed of two types of polymer particles, namely, particles composed of coalesced particles. Here, in order to obtain good removability, a particles are 50 to 90% by weight, preferably 60 to 80% by weight, and b particles are 50 to 10% by weight, preferably 40 to 20% by weight. Is good.

The water-dispersible pressure-sensitive adhesive for re-peeling is obtained by emulsion polymerization of the monomer mixture constituting the above-mentioned a particles to obtain an aqueous dispersion in which the above-mentioned a particles are emulsified and dispersed in water. The monomer constituting the b particles is emulsion-polymerized to obtain an aqueous dispersion in which the b particles are emulsified and dispersed in water, and the weight ratio of both the aqueous dispersions to both the a and b particles is within the above range. Can be prepared by blending as follows. In this case, as the monomer mixture constituting the a particles, the same as the monomer mixture constituting the A phase is used. As the monomer constituting the b particles, the same monomer as the monomer constituting the B phase is used. As for the polymerization initiator and the emulsifier, the same ones as in the case of the two-stage polymerization can be used.

The removable water-dispersible pressure-sensitive adhesive of the present invention comprises an aqueous dispersion containing two-phase polymer particles of A phase and B prepared as described above, or a particle and b particle. In any type of the aqueous dispersion containing the two kinds of polymer particles, various additives such as a tackifying resin, a cross-linking agent, a plasticizer, a softener, and a filler may be added to the aqueous dispersion as necessary. Agents, pigments, dyes, antioxidants, and the like.

The water-dispersible pressure-sensitive adhesive for re-peeling of the present invention can be directly applied to a suitable support such as plastic film, paper, metal foil, etc., according to the usual method for producing pressure-sensitive adhesive sheets. For re-peeling in sheet or tape form by coating and drying, or by coating and drying on a separator and then transferring it to an appropriate support It can be pressure-sensitive adhesive sheets.

[0024]

Next, an embodiment of the present invention will be described in more detail. Note that the present invention is not limited only to the following examples. In the following, all parts are parts by weight.

Example 1 In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser, 69 parts of 2-ethylhexyl acrylate, 1 part of methacrylic acid and 2 parts of sodium lauryl sulfate were added to water 123.
The mixture emulsified in the above portion was added, and the atmosphere was replaced with nitrogen for 1 hour while stirring. 0.02 parts of 2,2-azobis (2-methylpropionamidine) disulfate was added, and emulsion polymerization was carried out at a polymerization temperature of 50 ° C. for 5 hours. Thereafter, 30 parts of butyl acrylate was added, and the mixture was sufficiently stirred. Then, 2,2-azobis (2-methylpropionamidine) disulfate 0.01 parts was added again.
Then, emulsion polymerization was carried out at a polymerization temperature of 50 ° C. for 3 hours. It was neutralized with 10% by weight aqueous ammonia to obtain an aqueous dispersion containing polymer particles having a two-phase structure. To this aqueous dispersion, 0.1 part of an epoxy-based crosslinking agent and 15 parts of a rosin phenol-based tackifier (softening point of 125 ° C.) emulsion were added to 100 parts of the solid content, mixed well, and removed again. An aqueous dispersion type pressure-sensitive adhesive for use was prepared.

Next, on one side of Japanese paper having a basis weight of 30 g / m ² ,
An acrylic backsize agent (trade name “AE318” manufactured by Nippon Synthetic Rubber Co., Ltd.) was applied and dried at 130 ° C. for 3 minutes to form a filling layer having an applied amount of 10 g / m ² . The water-dispersible pressure-sensitive adhesive for re-peeling is applied to the opposite surface of the Japanese paper on which the filling layer is formed, and dried at 150 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm. After forming, a pressure-sensitive adhesive tape for re-peeling was prepared.

Example 2 In a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser, 69 parts of 2-ethylhexyl acrylate, 1 part of methacrylic acid and 1.4 parts of ammonium lauryl sulfate were emulsified with 74 parts of water. The resulting mixture was put in, and replaced with nitrogen for 1 hour while stirring. 0.02 parts of 2,2-azobis (2-methylpropionamidine) disulfate was added, and the polymerization temperature was 50 ° C.
Emulsion polymerization for 5 hours under the conditions described above. Then, again,
Azobis (2-methylpropionamidine) disulfate (0.01 part) was added, and 30 parts of butyl acrylate and 0.6 part of ammonium lauryl sulfate were emulsified with 15 parts of water. And dropped. Emulsion polymerization was carried out for a further 2 hours at a polymerization temperature of 50 ° C. 10
Neutralization was carried out with aqueous ammonia by weight to obtain an aqueous dispersion containing two-phase polymer particles. This aqueous dispersion has a solid content of 1
0.1 part of epoxy cross-linking agent, rosin phenol-based tackifier (softening point 125 ° C) emulsion 1
Five parts were added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. A pressure-sensitive adhesive tape for re-peeling was prepared in the same manner as in Example 1 except that this water-dispersible pressure-sensitive adhesive for re-peeling was used.

EXAMPLE 3 97 parts of 2-ethylhexyl acrylate, 1 part of methacrylic acid, 2 parts of methyl methacrylate, polyoxyethylene laurylphenyl were placed in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser. A solution obtained by emulsifying 3 parts of ammonium ether sulfate with 160 parts of water was added, and the mixture was purged with nitrogen for 1 hour while stirring. 0.03 parts of hydrogen peroxide was added to this,
A solution prepared by dissolving 0.03 part of sodium ascorbate in 10 parts of water was added dropwise at a polymerization temperature of 30 ° C.
Emulsion polymerization was carried out for hours. The resultant was neutralized with 10% by weight aqueous ammonia to obtain an aqueous dispersion Y1 containing polymer particles.

Separately, 100 parts of butyl acrylate, polyoxyethylene laurylphenyl ether were placed in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser.
A solution obtained by emulsifying 3 parts of ammonium tersulfate with 160 parts of water was added, and the mixture was purged with nitrogen for 1 hour while stirring. To this, 0.03 part of hydrogen peroxide was added, and a solution obtained by dissolving 0.03 part of sodium ascorbate in 10 parts of water was added dropwise.
Emulsion polymerization was carried out for 3 hours at a polymerization temperature of 10 ° C. The resultant was neutralized with 10% by weight aqueous ammonia to obtain an aqueous dispersion Y2 containing polymer particles.

The polymer particles 8 are added to the above aqueous dispersion Y1.
The above-mentioned aqueous dispersion Y2 was mixed with 0 parts so that the polymer particles became 20 parts. In addition to this, rosin phenol-based Takifiya (softening point 125 ° C) emulsion 1
Five parts and 0.1 part of an epoxy crosslinking agent were added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. A pressure-sensitive adhesive tape for re-peeling was produced in the same manner as in Example 1 except that this water-dispersed pressure-sensitive adhesive was used.

Example 4 The aqueous dispersion Y2 obtained in Example 3 was added to the aqueous dispersion Y1 obtained in Example 3 with respect to 60 parts of the polymer particles so that the polymer particles became 40 parts. Was mixed. To this, 15 parts of a rosin phenol-based tackifier (softening point: 125 ° C.) emulsion and 0.1 part of an epoxy-based crosslinking agent were added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. A pressure-sensitive adhesive tape for re-peeling was produced in the same manner as in Example 1 except that this water-dispersed pressure-sensitive adhesive was used.

Example 5 100 parts of butyl acrylate and 3 parts of ammonium polyoxyethylene lauryl ether sulfate were placed in a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser, and mixed with 160 parts of water.
The mixture emulsified in the above portion was added, and the atmosphere was replaced with nitrogen for 1 hour while stirring. Emulsion polymerization was carried out for 3 hours at a polymerization temperature of 50 ° C. while adding dropwise 0.03 part of hydrogen peroxide and dissolving 0.03 part of sodium ascorbate in 10 parts of water. The resultant was neutralized with 10% by weight aqueous ammonia to obtain an aqueous dispersion Y3 containing polymer particles.

To the aqueous dispersion Y1 obtained in Example 3, 60 parts of the polymer particles were mixed with 60 parts of the above-mentioned aqueous dispersion Y3 such that the polymer particles became 40 parts. Further, 0.1 part of an epoxy-based crosslinking agent was added thereto and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. A pressure-sensitive adhesive tape for re-peeling was produced in the same manner as in Example 1 except that this water-dispersed pressure-sensitive adhesive was used.

Comparative Example 1 The polymer particles 100 were added to the aqueous dispersion Y1 obtained in Example 3.
To each part, 15 parts of a rosin phenol-based tackifier (softening point: 125 ° C.) emulsion and 0.1 part of an epoxy crosslinking agent were added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. . A pressure-sensitive adhesive tape for re-peeling was produced in the same manner as in Example 1 except that this water-dispersed pressure-sensitive adhesive was used.

Comparative Example 2 The polymer particles 100 were added to the aqueous dispersion Y2 obtained in Example 3.
To each part, 15 parts of a rosin phenol-based tackifier (softening point: 125 ° C.) emulsion and 0.1 part of an epoxy crosslinking agent were added and mixed well to prepare a water-dispersible pressure-sensitive adhesive for re-peeling. . A pressure-sensitive adhesive tape for re-peeling was produced in the same manner as in Example 1 except that this water-dispersed pressure-sensitive adhesive was used.

With respect to the pressure-sensitive adhesive tapes for re-peeling prepared in Examples 1 to 5 and Comparative Examples 1 and 2, the self-backing property and the re-peeling property were examined by the following methods. These results were as shown in Table 1 below.

<Self-backside fixing property> A pressure-sensitive adhesive tape (width: 18 mm) for re-peeling was attached to a stainless steel plate, and the same type of pressure-sensitive adhesive was applied to the back surface (the surface on which the sealing layer was formed) of the pressure-sensitive adhesive tape. The pressure-sensitive adhesive layer side of the adhesive tape (18 mm in width) is overlaid and pressed back and forth with a 500 g roller, and then room temperature (2 mm).
(3 ° C.) for 30 minutes. Thereafter, the tape is left to stand at 80 ° C. for 10 minutes, and then, under an atmosphere of 80 ° C., so that the peeling angle is 90 ° from the tape application surface.
A load of 0 g was applied and the peel distance (cm) after 1 hour was measured.

<Removability> Pressure-sensitive adhesive tape (width 18 m)
m) was adhered to a melamine coated plate, and a lacquer coating was sprayed thereon, and the mixture was put into a hot air oven at 80 ° C. for 1 hour and dried. Immediately after being removed from the hot air oven, the pressure-sensitive adhesive tape was peeled off from the melamine coated plate, and the state of the adhesive residue on the melamine coated plate was visually judged according to the following criteria. ：: no adhesive residue △: partial adhesive residue ×: adhesive residue on the entire surface

[0039]

As is clear from the results in Table 1 above, each of the pressure-sensitive adhesive tapes for peeling of Examples 1 to 5 of the present invention was
Satisfies the self-backside fixing property, and more easily peels off without sticking residue due to cohesive failure even after being exposed to high temperature after being attached to the adherend, as compared with those of Comparative Examples 1 and 2. It turns out that it can be done.

In Example 4, when mixing the aqueous dispersions Y1 and Y2, the mixing ratio of the aqueous dispersion Y2 was further increased, for example, the polymer particles of the aqueous dispersion Y1 were reduced by 30%.
When the polymer particles of the aqueous dispersion Y2 were 70 parts by mass, the removability tended to decrease. From these results, it was confirmed that it is preferable to mix both dispersions Y1 and Y2 such that the former polymer particles are 50 to 90% by weight and the latter polymer particles are 50 to 10% by weight. Was done.

[0042]

As described above, according to the present invention, two-phase polymer particles having different monomer compositions are produced, or two types of polymer particles having different monomer compositions are produced. By blending, in particular, as the different monomer composition, one contains a carboxyl group-containing monomer, and the other does not contain a carboxyl group-containing monomer and a functional monomer that reacts with a carboxyl group. As a result, the pressure-sensitive adhesive sheet for masking has excellent self-backing properties and can be easily peeled off from the surface of the adherend without causing cohesive failure even after being exposed to a high temperature atmosphere after pasting to the adherend. The present invention can provide an acrylic pressure-sensitive adhesive for re-peeling, which is useful as, for example, adhesives.

 ──────────────────────────────────────────────────の Continued from the front page (72) Yoshinori Yoshida, Inventor 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (4)

[Claims] The polymer particles emulsified and dispersed in water are as follows: A)
A phase comprising a copolymer of a monomer mixture containing a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as a main component and a carboxyl group-containing monomer;
B) The weight of a monomer mainly containing an alkyl (meth) acrylate having an alkyl group of 4 to 12 carbon atoms and not containing a carboxyl group-containing monomer and a functional monomer that reacts with the carboxyl group. A water-dispersible pressure-sensitive adhesive for re-peeling, which has a two-phase configuration including a phase comprising a united body. 2. The composition according to claim 1, wherein the phase A constituting the polymer particles is 50 to 90.
The water-dispersible pressure-sensitive adhesive for re-peeling according to claim 1, wherein the content of the B-phase is 50 to 10% by weight. 3. The polymer particles emulsified and dispersed in water, comprising: a)
Particles composed of a copolymer of a monomer mixture containing a (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms as a main component and a carboxyl group-containing monomer,
b) The weight of a monomer containing an alkyl (meth) acrylate having 4 to 12 carbon atoms in the alkyl group as a main component and not containing a carboxyl group-containing monomer and a functional monomer that reacts with the carboxyl group. A water-dispersible pressure-sensitive adhesive for re-peeling, which comprises two kinds of polymer particles including particles of coalescing. 4. The method according to claim 1, wherein the a particles constituting the polymer particles are 50 to 9
The removable water-dispersible pressure-sensitive adhesive according to claim 3, wherein 0% by weight and b particles are 50 to 10% by weight.