JPH0726232A - Production of aqueous dispersion of self-adhesive, and self-adhesive tape or sheet - Google Patents

Abstract

PURPOSE:To obtain the subject dispersion which has good tackiness and holding power and maintains the tackiness without changing even under wet conditions by producing a specific acrylic copolymer in the presence of a specified amt. of an aq. emulsion of a tackifying resin. CONSTITUTION:This aqueous dispersion is obtd. by producing an acrylic copolymer by copolymerizing 60-97wt.% (meth)acrylic ester monomer of the formula (wherein R1 is H or methyl; and R2 is 4-14C alkyl) (e.g. 2-ethylhexyl acrylate) with 0.5-10wt.% monomer selected from the group consisting of a carboxylated monomer, an amidated monomer, a hydroxylated monomer, and an aminated monomer (e.g. acrylic acid) in the presence of an aq. emulsion which is prepd. by emulsifying 3-30 pts.wt. (based on 100 pts.wt. acrylic copolymer produced as above) tackifying resin with an emulsifier having a copolymerizable double bond.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aqueous dispersion of an adhesive. The aqueous dispersion of this pressure-sensitive adhesive is useful as a pressure-sensitive adhesive for pressure-sensitive adhesive tapes, sheets, labels, and double-sided pressure-sensitive adhesive tapes.

[0002]

_2. Description of the Related Art Acrylic copolymers obtained by copolymerizing an acrylic ester monomer represented by the general formula CH ₂ = CR ₁ -COOR ₂ [Formula 1] alone or with other monomers. It is already known that a tackifying resin is added to this to make an adhesive that can be used for an adhesive tape. This is what is called an acrylic adhesive. Acrylic pressure-sensitive adhesives are far superior to natural rubber or synthetic rubber-based pressure-sensitive adhesives that have been used so far in terms of constant tackiness, durability and the like. Therefore, acrylic adhesives have come to be widely used in place of rubber adhesives.

The acrylic pressure-sensitive adhesive is obtained by adding a tackifying resin to the acrylic copolymer as described above. The acrylic copolymer is the acrylic monomer represented by the above [formula 1]. Is copolymerized with other monomers. As the other monomer, a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, an amino group-containing monomer, or the like was used. The copolymerization ratio of the acrylic monomer is 60 to 97% by weight,
Other monomers were made to account for 0.5-10% by weight.

Acrylic adhesives have been designed to utilize organic solvents without the use of organic solvents in order to deal with pollution or environmental problems, and are therefore intended for use as aqueous dispersions. However, the acrylic pressure-sensitive adhesive is unstable in the form of an aqueous dispersion and has a drawback that the dispersed particles of the acrylic pressure-sensitive adhesive are likely to aggregate. This is because the acrylic copolymer itself tends to aggregate in the form of an aqueous dispersion, but since the tackifying resin is added to this, the dispersed particles become even more likely to aggregate. Therefore, the aqueous dispersion of the acrylic pressure-sensitive adhesive cannot be made into a high-concentration, that is, a dispersion having a high solid content, and even if a high-concentration dispersion is obtained, it is unstable and therefore it is placed on the sheet. When the coating was attempted, the particles agglomerated and the coating could not be performed uniformly. Therefore, it was attempted to increase the amount of the emulsifier to stabilize the dispersion, but if the amount of the emulsifier is increased, the emulsifier oozes out on the surface after the dispersion is formed into a film, resulting in a decrease in the adhesive strength. The result was Therefore, it has been desired to develop a stable aqueous dispersion of a pressure-sensitive adhesive containing an acrylic copolymer, which does not reduce the adhesive strength.

Hydrocarbons, terpenes, and rosins have been used as tackifying resins to be added to acrylic copolymers. When trying to obtain an aqueous dispersion of an acrylic pressure-sensitive adhesive, these tackifying resins were added as an aqueous dispersion to an aqueous dispersion of an acrylic copolymer. To make an aqueous dispersion of a tackifier resin, the tackifier resin is dissolved in an organic solvent, a surfactant or an emulsifier is added to this, and this is added to an aqueous medium for emulsification and dispersion, and then an organic solvent is added. The method of driving out was adopted. In this case, it has been considered that the surfactant or emulsifier used may be nonionic, anionic or cationic. Those surfactants or emulsifiers were high in saturated compounds.
However, JP-A-4-202488 discloses that an acrylic acid alkyl ester is polymerized in the presence of a reactive surfactant having two or more polymerizable functional groups to prepare an aqueous dispersion of a tackifying resin. It has been described.

[0006]

DISCLOSURE OF THE INVENTION The present invention is an aqueous dispersion of an acrylic pressure-sensitive adhesive obtained by adding a tackifying resin to an acrylic copolymer, and the dispersed particles are less likely to aggregate. It is intended to provide a stable aqueous dispersion of an adhesive. Moreover, this aqueous dispersion is stable even at a high concentration and is intended to be provided as a dispersion having a high solid content.
Furthermore, when the aqueous dispersion of this pressure-sensitive adhesive is applied onto a supporting substrate to form a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer has a strong adhesive force and a large peeling force, and further has a holding force, particularly a holding force when wet. It provides an excellent adhesive tape or sheet.

[0007]

The inventors of the present invention have found that when a tackifier resin is dispersed in an aqueous medium to form an aqueous dispersion of the tackifier resin, a special emulsifier is used to obtain the obtained tackifier resin. The dispersion of (1) becomes stable, and therefore, when this dispersion is added to the dispersion of the acrylic copolymer, the obtained aqueous dispersion of the acrylic pressure-sensitive adhesive becomes stable and dispersed particles do not easily aggregate. I found it. In this case, the special emulsifier is a surfactant having a structure in which a group containing a reactive double bond such as a propenyl group is added to a nonionic surfactant such as polyoxyethylene nonylphenyl ether. That is, generally, an aqueous dispersion of a tackifying resin was prepared using an emulsifier having a copolymerizable double bond, and this was added to a dispersion of an acrylic copolymer to prepare a dispersion. It has been found that the aqueous dispersion becomes stable, and the pressure-sensitive adhesive obtained therefrom has a suitable peeling force and a sufficient holding force. The present invention has been completed based on such knowledge.

This invention relates to 60 to 97% by weight of an acrylic acid ester monomer represented by the general formula CH ₂ ═CR ₁ —COOR ₂ [Formula 1] with a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, And an acrylic copolymer 100 obtained by copolymerizing 0.5 to 10 wt% of a second monomer selected from the group consisting of amino group-containing monomers.
In preparing an aqueous dispersion containing 3 parts by weight of tackifying resin and 3 to 30 parts by weight of tackifying resin, the above tackifying resin is used as an aqueous dispersion of the acrylic copolymer with an emulsifier having a copolymerizable double bond. The present invention provides a method for producing an aqueous dispersion of a pressure-sensitive adhesive, which is characterized by being added to.

The method of the present invention is premised on the use of an acrylic copolymer as a resin, and the tackifying resin for the resin is converted into an acrylic copolymer by using an emulsifier having a copolymerizable double bond as an aqueous dispersion. The feature is that it is added. Since the resin used here is an acrylic copolymer, as the tackifying resin, a known one such as a hydrocarbon type, a terpene type, or a rosin type is used. For example, Alcon P115 (hydrogenated petroleum resin) manufactured by Arakawa Chemical Co., Foral 105 (hydrogenated rosin resin) manufactured by Rika Hercules Co., Ltd., Pencel D-150 (polymerized rosin resin) manufactured by Arakawa Chemical Co., Ltd. can be used. .

The acrylic copolymer used is represented by the formula [1] with a second monomer selected from the group consisting of a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, and an amino group-containing monomer. It is a copolymer with an acrylic acid ester monomer. The copolymerization ratio is such that the second monomer accounts for 0.5 to 10% by weight and the acrylic ester monomer accounts for 60 to 97% by weight.

The acrylic ester monomer is a compound represented by the above [Formula 1]. In [Formula 1],
R ₁ represents hydrogen or a methyl group, and R ₂ has 4 to 1 carbon atoms.
4 represents an alkyl group. Therefore, the acrylic acid ester monomer is, for example, 2-ethylhexyl acrylate, isooctyl acrylate, lauryl methacrylate or the like, and these can be used alone or in combination. The reason why the acrylic acid ester monomer is limited to the above weight% is that when the acrylic acid ester monomer is 60% by weight or less, the copolymer obtained by copolymerizing the acrylic acid ester monomer is
This is because it has an excessively large cohesive force, and therefore the adhesive made from this has poor adhesiveness at low temperatures. On the contrary, when it is 97% by weight or more, it has an excessively small cohesive force. This is because the adhesive becomes inferior in creep resistance.

The second monomer is used by selecting from four types of monomers. The four types of monomers are a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, and an amino group-containing monomer. The carboxyl group-containing monomer is, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, or their acid anhydrides. Examples of the amide group-containing monomer include substituted acrylamides such as acrylamide, methacrylamide, N-isopropylacrylamide, N-methylolacrylamide, and cyclic amides such as N-vinylpyrrolidone and acryloylmorpholine. The hydroxyl group-containing monomer is, for example, 2-hydroxyethyl acrylate, 2-
Examples thereof include hydroxyethyl methacrylate and 4-hydroxybutyl acrylate. The amino group-containing monomer is, for example, dimethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide, diethylaminoethyl methacrylate, or the like.

As the second monomer, one of the above four types can be used alone or two or more types can be mixed and used. The amount is such that the second monomer accounts for 0.5 to 10% by weight in the acrylic copolymer. The reason is that when the second monomer is 0.5% by weight or less, the obtained acrylic copolymer has a weak cohesive force and is not suitable for use, and when it is 10% by weight or more, the obtained acrylic copolymer is obtained. The cohesive force of the copolymer becomes too strong,
This is because it is no longer suitable for use with arrow sticks.

In addition, among the acrylic copolymers,
It is also possible to add and copolymerize a third monomer having a medium polarity such as styrene, vinyl acetate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate. However, the ratio of the third monomer in the acrylic copolymer is 40% by weight.
Must be: The reason is that when the content of the third monomer is 40% by weight or more, the cohesive force of the obtained acrylic copolymer becomes too strong.

An emulsifier having a copolymerizable double bond (hereinafter,
This is abbreviated as unsaturated emulsifier) means a surfactant having a polyoxyethylene chain such as polyoxyethylene alkyl ether sulfonate or polyoxyethylene alkylphenol sulfate, a propenyl group, an allyl group, an acryloyl group. , A compound having an unsaturated group such as a methacryloyl group or a maleic acid group added thereto. Such compounds are commercially available. For example, a surfactant sold by Dai-ichi Kogyo Seiyaku Co., Ltd. under the name of Aqualon RN-20 is a polyoxyethylene nonylphenyl ether having 20 moles of ethylene oxide added and a propenyl group added thereto. From the company Aqualon H
The surfactant sold under the name of S-10 is a polyoxyethylene nonylphenyl ether ammonium sulfate salt to which a propenyl group is added, and both of them correspond to the unsaturated emulsifier in the present invention. It is used as an unsaturated emulsifier in, and gives good results.

The unsaturated emulsifier is preferably used in an amount of 1 to 10 parts by weight, more preferably 2 to 4 parts by weight, based on 100 parts by weight of the tackifying resin. The reason is that if it is less than 1 part by weight, the mechanical stability of the dispersion when the tackifying resin is made into an aqueous dispersion is lowered, and if it exceeds 10 parts by weight, it takes a long time to complete the reaction of the emulsifier. This is because productivity is reduced. When the above-mentioned amount of the unsaturated emulsifier used is converted into 100 parts by weight of the total amount of the tackifying resin and the acrylic copolymer, it becomes approximately 0.4 to 2 parts by weight.

In the present invention, when an unsaturated emulsifier is used, an ordinary nonionic surfactant can be used together. For example, polyoxyethylene nonylphenyl ether, polyoxyethylene alkylaryl ether and the like can be used in combination. A single nonionic surfactant may be used, or two or more nonionic surfactants having different HLB values may be mixed and used. However, when an ordinary surfactant is used in combination, the total amount of the ordinary surfactant and the unsaturated emulsifier is 2 parts by weight or less based on 100 parts by weight of the acrylic copolymer and the tackifying resin. And

In the method of the present invention, it is necessary to form the tackifying resin into an aqueous dispersion with an unsaturated emulsifier. To do this, first dissolve the tackifier resin in an organic solvent, add an aqueous solution of an unsaturated emulsifier to it, and stir it well to form an emulsion, then dry it under reduced pressure with an aspirator to drive off the organic solvent, thus dispersing the tackifier resin in water. Get the body.
As the organic solvent, for example, benzene, toluene, ethyl acetate, acetone or the like can be used. Alternatively, the tackifying resin may be heated and melted, and the unsaturated emulsifier and water may be mixed under high pressure to form an aqueous dispersion.

Various methods can be used to obtain an aqueous dispersion of the pressure-sensitive adhesive according to the present invention using the above-mentioned aqueous dispersion of the tackifying resin. For example, after obtaining the acrylic copolymer, the aqueous dispersion of the tackifying resin may be added thereto, and before obtaining the acrylic copolymer, that is, the acrylic ester monomer and the second monomer are added. In the step of coexisting with, the aqueous dispersion of tackifying resin may be added, and the above-mentioned monomer may be copolymerized in the presence of the aqueous dispersion of tackifying resin. In this case, a mixture of the acrylic ester monomer and the second monomer may be copolymerized as an aqueous dispersion with an unsaturated emulsifier.

In order to prepare an acrylic acid type copolymer, a batch charging method in which a polymerization initiator, a monomer and an emulsifying agent are allowed to exist in water to carry out polymerization according to a known method can be adopted. A monomer dropping method in which a monomer is dropped into water in which an initiator is present, or an emulsified monomer dropping method in which a monomer, an emulsifier, and water are mixed and emulsified in advance and the emulsified monomer dispersion is dropped into water in which a polymerization initiator is dissolved. Although the method can be adopted, it is preferable to use the monomer dropping method in order to obtain an aqueous dispersion of an adhesive having a high solid content.

The pressure-sensitive adhesive according to the present invention may be adjusted in molecular weight by using a chain transfer agent such as dodecyl mercaptan, or a pH adjusting agent such as amine or caustic soda, polyacrylate, water-soluble urethane resin. Viscosity modifiers such as, defoaming agents, preservatives, epoxy crosslinking agents, aziridine crosslinking agents,
You may add a blocked isocyanate type crosslinking agent etc.
However, the mixing stability of the viscosity modifier, the cross-linking agent and the like is better if they are added after mixing the tackifying resin.

The aqueous dispersion of the pressure-sensitive adhesive obtained by the present invention can be applied to one side or both sides of a base material by a conventional method and dried to form a pressure-sensitive adhesive tape or sheet.

[0023]

According to the present invention, the tackifying resin is made into an aqueous dispersion with an unsaturated emulsifier, and the aqueous dispersion of the tackifying resin thus obtained is added to the acrylic polymer, so that the dispersed particles aggregate. It is difficult to obtain a stable aqueous dispersion of the acrylic pressure-sensitive adhesive. Moreover, this aqueous dispersion is stable even at a high concentration and can be provided as a dispersion having a high solid content. Therefore, it is convenient to use as an adhesive. Furthermore, even when this dispersion is applied to a supporting substrate to form, for example, a pressure-sensitive adhesive tape, the unsaturated emulsifier is firmly held in the tackifying resin. The emulsifier does not bleed out on the surface of the pressure-sensitive adhesive, and therefore the water resistance is not likely to decrease, and the amount of the usual free emulsifier is reduced so that the pressure-sensitive adhesive can be retained for a long time. be able to. The present invention provides such benefits.

[0024]

[Examples] Hereinafter, the reason why the method of the present invention is excellent will be specifically described by giving Examples and Comparative Examples. In the following, simply "parts" means "parts by weight".

Example 1 (Production of Aqueous Dispersion of Tackifying Resin) As the tackifying resin, a hydrogenated rosin resin (Foral 105, manufactured by Rika Hercules Co., Ltd.) having a softening point of 105 ° C. and a softening point of 150 ° C. A polymerization rosin (Pencel D-150, manufactured by Arakawa Chemical Co., Ltd.) was mixed and used. As the unsaturated emulsifier, a nonionic surfactant (Aqualon RN-20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) in which a propenyl group was added to a polyoxyethylene nonylphenyl ether ammonium sulfate salt having an ethylene oxide addition mole number of 20 was used.

75 parts of the hydrogenated rosin resin and 50 parts of the polymerized rosin resin are dissolved in 125 parts of ethyl acetate, and 3.5 parts of the unsaturated emulsifier is dissolved in the ion-exchanged water 7
0 was added to emulsify and disperse. Next, this was decompressed with an aspirator, and ethyl acetate was expelled to obtain a solid content of 43.0%.
An aqueous dispersion of the tackifying resin of was obtained.

(Production of Acrylic Copolymer) Ion-exchanged water prepared by dissolving 0.1 part of ammonium persulfate in a 1 liter reactor equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube. Add 50 parts and 70 under nitrogen atmosphere
Warmed to ° C. Separately, 20 parts of 2-ethylhexyl acrylate (2EHA), butyl acrylate (BA) 74
Parts, methacrylic acid (MAc) 6 parts, a nonionic surfactant obtained by adding a propenyl group to polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 20 as an unsaturated emulsifier (Daiichi Kogyo Seiyaku Co., Ltd., Aqualon
RN-20) 0.3 parts, a surfactant obtained by adding a propenyl group to ammonium polyoxyethylene nonylphenyl ether sulfate (Daiichi Kogyo Seiyaku Co., Ltd., Aqualon HS
-10) 0.6 part and 30 parts of ion-exchanged water were mixed and stirred to prepare an emulsified monomer mixture, which was placed in a dropping funnel and dropped into the reactor kept at 70 ° C. over 3 hours. , The monomers were copolymerized. The conversion rate at this point is 7
It was 4.3%.

(Production of Aqueous Adhesive Aqueous Dispersion) 58.1 parts of the above tackifying resin aqueous dispersion was dropped into the reaction vessel from the dropping funnel over 1 hour, and the dropping funnel was charged with 1 part of ion-exchanged water. After washing and dropping into the reactor, 0.1 part of ammonium persulfate was added and kept at 70 ° C. for 1 hour, then
The temperature was raised to 0 ° C. and the reaction was performed for 1 hour. The conversion rate was 99% or more.

After cooling the polymerization solution to 30 ° C. or lower, 25%
Neutralized with aqueous ammonia. A urethane-based thickener (Adecan UH-420, manufactured by Asahi Denka Co., Ltd.) was added as a thickener, and the mixture was stirred and mixed, and then filtered through a 200-mesh stainless wire mesh to obtain an aqueous dispersion of an adhesive.

The obtained aqueous dispersion of pressure-sensitive adhesive had a pH of 7.
8. The viscosity was 12000 cps at 30 ° C. Aziridine type curing agent (Nippon Shokubai Co., DZ-22E) 0.8
Parts of the solution is applied to a release-treated polyester film so that the glue thickness after drying is 60 μm, and dried, then transferred to both sides of a nonwoven fabric with a basis weight of 14 g / m ² to create a double-sided adhesive tape. did. The applied glue film was smooth without streaks due to agglomerates and repelling.

With respect to the obtained pressure-sensitive adhesive tape, the peeling force with respect to SUS, the peeling force with respect to PP, the holding power at 40 ° C., and the wet holding power were measured, and the goodness and badness thereof were evaluated together.

Peel force against SUS is 1470 gf / 20 mm
The peeling force against PP was 1320 gf / 20 mm, the holding power at 40 ° C had a deviation length of 0.02 mm, and the wet holding power had a deviation length of 0.08 mm, which were good evaluations.

The peeling force against SUS is JIS Z 1
According to 528, 180 degree peeling adhesion to a stainless steel plate was measured. The peeling force against pp is JIS Z 1
According to 528, the 180 degree peeling adhesion to the polypropylene plate was measured. 40 ° C holding power is JIS Z
Adhering area according to 1528 20mm x 20mm
Then, a load of 1 kg was applied in an atmosphere of 40 ° C., and the shift length after 1 hour was measured. For those that could not be held for 1 hour, the fall time was measured. Wet holding power is 40 ℃, 90% RH
In an atmosphere of 20mm x 20mm, 1
A load of Kg was applied, the shift length after 1 hour was measured, and the fall time was measured for those that could not be held for 1 hour.

Example 2 (Production of Aqueous Dispersion of Tackifying Resin) As the tackifying resin, hydrogenated petroleum resin (Arakawa Chemical Co., Alcon P115) having a softening point of 115 ° C. was used. As an unsaturated emulsifier,
A surfactant (Aqualon HS-20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used in which a propenyl group was added to ammonium polyoxyethylene nonylphenyl ether sulfate having an ethylene oxide addition mole number of 20.

100 parts of the hydrogenated petroleum resin was mixed with 1 part of ethyl acetate.
60 parts of ion-exchanged water in which 1.5 parts of the above-mentioned Aqualon HS-20 was dissolved, was stirred and emulsified and dispersed. Next, this was decompressed with an aspirator, and ethyl acetate was expelled to obtain an aqueous dispersion of tackifying resin having a solid content of 45.2%.

(Production of Aqueous Dispersion of Adhesive) 22.1 parts of the aqueous dispersion of the tackifying resin obtained above and 38 parts of ion-exchanged water in which 0.1 part of ammonium persulfate was dispersed were charged into a reactor. The temperature was raised to 70 ° C. Separately, BA 46 parts, 2E
HA 50 parts, MAc 2 parts, N-vinylpyrrolidone (NVP) 2 parts, n-dodecyl mercaptan (DDM)
0.03 parts, 0.6 parts of a nonionic surfactant (Aqualon RN-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) in which a propenyl group is added to polyoxyethylene nonylphenyl ether having an ethylene oxide addition mole number of 10 as an unsaturated emulsifier. Monomers obtained by mixing 0.4 parts of a surfactant (Aqualon HS-20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) in which a propenyl group is added to ammonium polyoxyethylene nonylphenyl ether sulfate, and 30 parts of ion-exchanged water, and stirring to emulsify the monomer. A mixture was prepared and dropped into the above reaction vessel kept at 70 ° C. for 3 hours to copolymerize the monomers.

Thereafter, the same procedure as in Example 1 was carried out to obtain an aqueous dispersion of the pressure-sensitive adhesive. Using the obtained aqueous dispersion of the pressure-sensitive adhesive, a pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, and its peeling force and holding force were measured. Peel strength against SUS is 152
0gf / 20mm, peeling force against PP is 1460gf
/ 20 mm, the holding power at 40 ° C has a deviation length of 0.05
mm, and the wet retention force was 0.12 mm in the deviation length, which was evaluated as good as a whole.

(Example 3) Polymerization was carried out in the same manner as in Example 1, and after the dropping of the monomer was completed, the temperature was raised to 80 ° C and aging was carried out for 2 hours to complete the polymerization reaction. At this point the conversion rate is 98.5%
Met. With the reaction liquid kept at the same temperature, 22.1 parts of the tackifying resin dispersion liquid prepared in Example 2 and 0.05 part of ammonium persulfate were added and reacted at the same temperature for 1 hour to obtain an aqueous dispersion. . Using the obtained aqueous dispersion of the pressure-sensitive adhesive, a pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, and its peeling force and holding force were measured. Peel force against SUS is 1500 gf /
20 mm, peeling force against PP is 1410 gf / 20 m
m, the holding power at 40 ° C. had a deviation length of 0.05 mm, and the wet holding power had a deviation length of 0.08 mm, which was evaluated as good as a whole.

Comparative Example 1 0.8 parts of polyoxyethylene nonylphenyl ether (Neugen EA-170, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was used as the nonionic surfactant, and polyoxyethylene alkylphenyl was used as the anionic surfactant. An aqueous dispersion of the pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the amount of the ammonium sulfate ether salt (Eleminol ES-20 manufactured by Sanyo Kasei Co., Ltd.) was changed to 0.6 part.

Using this aqueous dispersion, an adhesive tape was prepared in exactly the same manner as in Example 1, and its peeling force and holding force were measured. Peel force to SUS is 1450 gf / 20 mm, Peel force to PP is 1340 gf / 20 mm,
Since the holding power at 40 ° C dropped in 45 minutes and the holding power in wet dropped in 40 minutes, it was evaluated as poor as a whole.

Comparative Example 2 A pressure-sensitive adhesive was prepared in the same manner as in Example 2 except that a tackifying resin dispersion (Super Ester E-740 manufactured by Arakawa Chemical Co., Ltd.) dispersed with a non-reactive surfactant was used. An aqueous dispersion of

Using this aqueous dispersion, an adhesive tape was prepared in exactly the same manner as in Example 1, and its peeling force and holding force were measured. Peel force to SUS is 1430 gf / 20 mm, Peel force to pp is 1380 gf / 20 mm, 4
The 0 ° C. holding force had a deviation of 0.12 mm, but the wet holding force dropped in 40 minutes, so that it was evaluated as poor as a whole.

Claims (4)

[Claims] 1. A (meth) acrylic acid ester monomer 60 represented by the general formula CH ₂ ═CR ₁ —COOR ₂ [Formula 1]
0.5% of the second monomer selected from the group consisting of a carboxyl group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, and an amino group-containing monomer in 97% by weight.
In producing an aqueous dispersion containing 100 parts by weight of an acrylic copolymer obtained by copolymerizing 10 to 10% by weight and 3 to 30 parts by weight of a tackifying resin, the tackifying resin is copolymerized. A method for producing an aqueous dispersion of a pressure-sensitive adhesive, comprising an aqueous dispersion emulsified with an emulsifier having a functional double bond, which is present during the production of the acrylic copolymer. However, in the formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group having 4 to 14 carbon atoms. 2. A (meth) acrylic acid ester monomer emulsified with an emulsifier having a copolymerizable double bond and an emulsifier with an emulsifier having a copolymerizable double bond are added to an aqueous dispersion of a tackifying resin emulsified with an emulsifier having a copolymerizable double bond. The pressure-sensitive adhesive according to claim 1, wherein the aqueous dispersion of the monomer (2) is added dropwise and the (meth) acrylic acid ester monomer and the second monomer are copolymerized in the presence of a polymerization initiator. A method for producing an aqueous dispersion. 3. A monomer mixture preliminarily emulsified with an emulsifier having a copolymerizable double bond is dropped into water containing a polymerization initiator to polymerize, and in the process, an emulsifier having a copolymerizable double bond. The method for producing an aqueous dispersion of a pressure-sensitive adhesive according to claim 1, characterized in that the aqueous dispersion of the tackifying resin dispersed according to (1) is added dropwise and the polymerization is further continued. 4. A pressure-sensitive adhesive tape or sheet obtained by using the aqueous dispersion of the pressure-sensitive adhesive obtained by the method according to claim 1.