JP2007112896A - Method for producing emulsion type acrylic pressure-sensitive adhesive and emulsion type acrylic pressure-sensitive adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an emulsion type acrylic pressure-sensitive adhesive by which a polymer emulsion (an acrylic emulsion) can be produced with good polymerization stability without using nonylphenol as an emulsifying agent. <P>SOLUTION: The polymer emulsion is obtained as follows. A monomer mixture is subjected to emulsion polymerization in the presence of an emulsifying agent containing a monoalkyl succinate sulfonate and another emulsifying agent in a mixing ratio of (95:5) to (70:30) (weight ratio). The monomer mixture contains the following monomers in the compounding ratio of 60-85 wt.% of a first (meth)acrylic monomer represented by general formula (1) H<SB>2</SB>C=C(R<SP>1</SP>)COOR<SP>2</SP>[wherein, R<SP>1</SP>represents a hydrogen or a methyl group; and R<SP>2</SP>represents a 5-12C alkyl group], 10-30 wt.% of a second (meth)acrylic monomer represented by general formula (2) H<SB>2</SB>C=C(R<SP>3</SP>)COOR<SP>4</SP>[wherein, R<SP>3</SP>represents a hydrogen or a methyl group; and R<SP>4</SP>represents a 1-4C alkyl group] and 2-10 wt.% of a carboxy group-containing vinyl monomer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an emulsion-type acrylic pressure-sensitive adhesive and an emulsion-type acrylic pressure-sensitive adhesive.

  As medical adhesives used for medical adhesive tapes and sheet adhesive layers to be applied to the skin, acrylic adhesives mainly composed of (meth) acrylic acid alkyl esters, natural rubber, synthetic Rubber-based adhesives mainly composed of rubber are used. However, it is relatively difficult to adjust the adhesive properties of rubber-based adhesives, and adhesives using natural rubber have some difficulties in handling such as the risk of allergy due to proteins as impurities. Therefore, recently, an acrylic pressure-sensitive adhesive whose adhesion characteristics can be easily adjusted by a polymerization method, a polymerization composition, blending, and the like has been increasingly used.

On the other hand, emulsion type adhesives, unlike organic solvent-soluble type adhesives, can be applied without solvent, so they are superior in terms of environmental hygiene and safety. Especially, emulsion type acrylic adhesives are adhesive. Because of its excellent properties, it is used in various fields. An emulsion-type adhesive is obtained by emulsifying (dispersing) an adhesive polymer (adhesive) in water in the presence of an emulsifier. In an acrylic adhesive, a (meth) acrylic acid alkyl ester is used. Obtained by emulsion polymerization in the presence of an emulsifier (that is, a polymer emulsion obtained by emulsion polymerization (aqueous dispersion of polymer) can be used as an emulsion-type pressure-sensitive adhesive as it is) Therefore, it is advantageous from the viewpoint of manufacturing. However, many of the emulsifiers contained in the emulsion-type acrylic pressure-sensitive adhesive have a problem in that they contain nonylphenol. That is, nonylphenol is toxic to endocrine organs as an environmental hormone substance having estrogenic activity (Non-patent Documents 1-2, European Directives 2003/53 / EC and 76/769 / EEC Addendum INo. 46), and It was pointed out that the endocrine disrupting action was confirmed by the endocrine disrupting chemicals problem study group in Japan in August 2001 (2001), and that this is a causative agent for environmental problems that cause cancer, malformations, and the like. It is also known to be strongly irritating to the eyes, skin and respiratory system (Non-Patent Documents 3 to 4), and to show corrosiveness by extending the exposure time for the skin irritation test. Therefore, in emulsion type acrylic pressure-sensitive adhesives, in particular, emulsion type acrylic pressure-sensitive adhesives for medical use that are in direct contact with the skin (skin) of the living body, it has become necessary to move to alternatives that do not contain nonylphenol as an emulsifier. However, it is not easy to perform emulsion polymerization of (meth) acrylic monomers stably without using nonylphenol as an emulsifier. Therefore, emulsion polymerization of (meth) acrylic monomers without using nonylphenol as an emulsifier Thus, there is a demand for a method capable of stably producing an emulsion-type acrylic pressure-sensitive adhesive exhibiting good adhesive properties. In addition, in the emulsion type acrylic pressure-sensitive adhesive, attempts have been made to improve the skin adhesiveness by adjusting the molecular weight of the polymer or to reduce the pain at the time of peeling, but it has been sufficiently improved. There is a need for an emulsion-type acrylic pressure-sensitive adhesive that has good skin adhesiveness and sufficiently reduces pain during peeling.
Laws, S.M. C. et al. , Estogenetic activity of octylphenol, nonylphenol, bisphenol A and methoxychlor in rats. Toxcol. Sci. , 54, 156-167, 2000 Lee, P.M. C. Description of male reproductive tract development by administration of the xenoestrogens, nonylphenol, to male newborn rats. Endocrine, 9, 105-111, 1998 U. S. Coast Guard, Department of Transportation. CHRIS-Hazardous Chemical Data. Volume II. Washington D.C. C. : U. S. Government Office. 1984-1985 Ikeda, et al. , Two cases of leukoderma, presumably due to nonyl- or octylphenol in synthetic detergents. Ind. Health 8,192-196, 1970

In view of the above circumstances, the problem to be solved by the present invention is an emulsion type acrylic pressure-sensitive adhesive that can produce an emulsion type acrylic pressure-sensitive adhesive exhibiting good adhesive properties with good polymerization stability without using nonylphenol as an emulsifier. It is to provide a manufacturing method.
In addition, an emulsion-type acrylic pressure-sensitive adhesive having excellent skin adhesiveness and sufficiently reducing pain at the time of peeling and excellent in environmental friendliness and the emulsion-type acrylic pressure-sensitive adhesive can be produced with good polymerization stability. Is to provide a method.

  As a result of diligent research to solve the above-mentioned problems, the present inventor found that an emulsion type acrylic copolymer with good polymerization stability can be obtained if it is emulsion polymerization using a monoalkyl succinate sulfonate and other emulsifier in a specific amount ratio. -Based pressure-sensitive adhesive can be produced, and by adjusting the monomer composition and the weight average molecular weight of the polymer (sol content) to a specific range, it has good skin adhesiveness and at the time of peeling. The present inventors have found that an emulsion-type acrylic pressure-sensitive adhesive that can sufficiently reduce the pain is obtained, and the present invention has been completed.

That is, the present invention is as follows.
[1] General formula (1): H ₂ C═C (R ¹ ) COOR ² [wherein R ¹ represents hydrogen or a methyl group, and R ² represents a C _{5 to} C ₁₂ alkyl group. 60 to 85% by weight of the first (meth) acrylic monomer represented by the general formula (2): H ₂ C═C (R ³ ) COOR ⁴ [wherein R ³ is hydrogen or a methyl group, R ⁴ represents a C _{1 to} C ₄ alkyl group. A monomer mixture containing 10 to 30% by weight of the second (meth) acrylic monomer represented by the formula (1) and 2 to 10% by weight of the carboxyl group-containing vinyl monomer, and a monoalkyl succinate sulfonate Emulsion polymerization in the presence of an emulsifier containing another emulsifier in a mixing ratio of 95: 5 to 70:30 (weight ratio).
[2] The method for producing an emulsion-type acrylic pressure-sensitive adhesive according to [1], wherein the other emulsifier is an anionic emulsifier or / and a nonionic emulsifier.
[3] The emulsion-type acrylic adhesive according to [1] or [2], wherein the amount of the emulsifier containing monoalkyl succinate sulfonate and other emulsifier is 0.3 to 5 parts by weight per 100 parts by weight of the monomer. Manufacturing method.
[4] An emulsion-type acrylic pressure-sensitive adhesive produced by the method according to any one of [1] to [3].
[5] The emulsion acrylic adhesive according to [4], wherein the polymer sol has a weight average molecular weight of 150,000 to 400,000.
[6] The emulsion acrylic pressure-sensitive adhesive according to [4] or [5], which is for medical use.
[7] A medical pressure-sensitive adhesive tape or sheet having a pressure-sensitive adhesive layer made of an emulsion-type acrylic pressure-sensitive adhesive according to any one of [4] to [6] on at least one side of a substrate.

According to the method for producing an emulsion-type acrylic pressure-sensitive adhesive of the present invention, an emulsion-type acrylic pressure-sensitive adhesive exhibiting excellent adhesion is obtained by emulsion polymerization without using nonylphenol as an emulsifier (that is, gelation or monomer). Without the separation of
In addition, the emulsion-type acrylic pressure-sensitive adhesive obtained by the production method of the present invention is not only a causative substance for environmental problems but also contains no nonylphenol having skin irritation, and has excellent adhesiveness. It can be applied to products that require tackiness in the technical field. In particular, by adjusting the monomer composition, the weight average molecular weight of the polymer (sol content), and the like, it is possible to realize an emulsion-type acrylic pressure-sensitive adhesive that has good skin adhesion and sufficiently reduces the pain at the time of peeling. It is particularly suitable for medical use, and is useful, for example, as an adhesive layer for medical adhesive tapes and sheets.

Hereinafter, the present invention will be described in more detail.
In the present invention, “(meth) acrylic monomer” means a main monomer component for imparting tackiness to an acrylic pressure-sensitive adhesive, and generally has 1 to 12 carbon atoms. The (meth) acrylic acid alkyl ester having an alkyl group is used.

In the present invention, the (meth) acrylic monomer is represented by the general formula (1): H ₂ C═C (R ¹ ) COOR ² [wherein R ¹ represents hydrogen or a methyl group, and R ² represents a C _{5 to} C ₁₂ alkyl group. And one or more of the first (meth) acrylic monomers represented by general formula (2): H ₂ C═C (R ³ ) COOR ⁴ [wherein R ³ is hydrogen or methyl The group R ⁴ represents a C _{1 to} C ₄ alkyl group. It is important to use one or more of the second (meth) acrylic monomers represented by

In the first (meth) acrylic monomer represented by the general formula (1) (that is, a (meth) acrylic acid alkyl ester having an alkyl group having 5 to 12 carbon atoms), it is represented by R ² in the formula The C _{5 to} C ₁₂ alkyl group may be linear or branched, and may be cyclic, but is preferably linear or branched. Specific examples of the first (meth) acrylic monomer include acrylic acid (R ^{2 in} the formula is a pentyl group, hexyl group, nonyl group, 2-ethylhexyl group, octyl group, decyl group, dodecyl group, etc.) Examples include alkyl esters of R ¹ in the formula (hydrogen) and methacrylic acid (R ² in the formula is a methyl group). Among these, 2-ethylhexyl acrylate and isooctyl acrylate are preferable.

On the other hand, in the second (meth) acrylic monomer represented by the general formula (2) (that is, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms), R ⁴ in the formula represents The C ₁ -C ₄ alkyl group may be linear or branched, and may be cyclic, but is preferably linear or branched. Specific examples of the second (meth) acrylic monomer include acrylic acid (wherein R ³ is hydrogen) and methacrylic acid in which R ⁴ is a methyl group, ethyl group, propyl group, butyl group, or the like. (Wherein R ³ is a methyl group) and the like, and among them, isobutyl (meth) acrylate is preferable.

  In the present invention, from the viewpoint of imparting an excellent internal cohesive force to the pressure-sensitive adhesive, the first and second (meth) acrylic monomers as well as the above-mentioned first and second (meth) acrylic monomers can be copolymerized with these. It is important to use a group-containing vinyl monomer (that is, it is important to use a monomer mixture comprising the first and second (meth) acrylic monomers described above and a carboxyl group-containing vinyl monomer). Examples of the carboxyl group-containing vinyl monomer include (meth) acrylic acid, itaconic acid, maleic acid, and crotonic acid. Among these, (meth) acrylic acid is preferable.

  In the present invention, the mixing ratio of the first (meth) acrylic monomer, the second (meth) acrylic monomer, and the carboxyl group-containing vinyl monomer in the monomer mixture is the first (meth) acrylic per monomer mixture. 60-85 wt% (preferably 60-80 wt%) of the monomer, 10-30 wt% (preferably 10-25 wt%) of the second (meth) acrylic monomer, 2 of the carboxyl group-containing vinyl monomer It is important to set it to 10 to 10% by weight (preferably 3 to 8% by weight).

  If the first (meth) acrylic monomer is less than 60% by weight, the adhesive properties may be impaired. Further, if the second (meth) acrylic monomer is less than 10% by weight, the adhesive properties may be impaired, and if it exceeds 30% by weight, there is a concern that aggregates are generated during polymerization. Furthermore, if the carboxyl group-containing vinyl monomer is less than 2% by weight, the molecular weight of the polymer becomes too large, and the adhesive properties (especially skin adhesiveness) may be impaired. There are concerns.

  In the present invention, it is necessary in addition to the above three main monomers (first (meth) acrylic monomer, second (meth) acrylic monomer, carboxyl group-containing vinyl monomer) as a monomer as a polymerization raw material. Depending on the type, other monomers may be further blended for the purpose of stabilizing emulsion particles, improving adhesion to a substrate when applied to an adhesive tape, etc., and improving initial adhesion to an adherend. . The amount of the other monomers can be appropriately selected according to the type of each monomer within a range of 1% by weight or less in the total monomer mixture, and two or more types may be used.

  Examples of the other monomers include (meth) acrylic acid alkyl esters having 13 to 18 carbon atoms in the alkyl group such as tridecyl (meth) acrylate and stearyl (meth) acrylate; vinyl acetate, styrene, vinyl toluene and the like. It is done. Also, neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, dipentaerythritol hexa ( Those having two or more polymerizable functional groups such as (meth) acrylate may be used.

  In the present invention, a monomer mixture containing at least a first (meth) acrylic monomer, a second (meth) acrylic monomer, and a carboxyl group-containing vinyl monomer is mixed with a monoalkyl succinate sulfonate and other emulsifier in a ratio of 95: 5. Emulsion polymerization is carried out in the presence of an emulsifier containing a mixing ratio of ˜70: 30 (weight ratio) to form a polymer emulsion (acrylic emulsion).

  The “monoalkyl succinate sulfonate” referred to in the present invention is a compound represented by the following general formula (3).

(In the formula, R ⁵ represents a C _{8 to} C ₁₂ alkyl group, m represents a natural number of 2 to 20, and X ¹ and X ² each represent a sodium atom or an ammonia molecule.)

In the monoalkyl succinate sulfonate represented by the general formula (3), the C _{8 to} C ₁₂ alkyl group represented by R ⁵ in the formula may be linear or branched, It may be cyclic, but is preferably linear or branched. X ¹ and X ² are preferably the same, and when they are the same, both X ¹ and X ² are preferably sodium atoms.

As the monoalkyl succinate sulfonate, a commercially available product may be used. As a specific example, “New Coal 293” (trade name) manufactured by Nippon Emulsifier Co., Ltd. (R ⁵ = C ₈ H ₁₇ , m = 2, ^{X 1, X 2 = Na)} , Japan emulsifier manufactured by "RA5411" (trade _{^{name) (R 5 = C 8 H}} 17, m = 20, X 1, X 2 = Na), Japan emulsifier manufactured by "RA544 (Trade name) (R ⁵ = C ₈ H ₁₇ , m = 8, X ¹ , X ² = Na) and the like.

  By using monoalkyl succinate sulfonate as an emulsifier, polymerization reaction of (meth) acrylic monomer and carboxyl group-containing vinyl monomer progresses without causing gelation and almost no agglomerates. It is possible to obtain a polymer emulsion (acrylic emulsion) having a high quality, that is, an emulsion-type acrylic pressure-sensitive adhesive. Such an excellent polymerization stabilizing effect is presumed to be due to the interaction between the carboxyl group in the emulsifier and the carboxyl group in the acrylic polymer.

  Moreover, in this invention, it is important to use said monoalkyl succinate sulfonate by the mixing ratio of 95: 5-70: 30 (weight ratio) with another emulsifier. As the other emulsifiers, known emulsifiers for emulsion polymerization (excluding nonylphenol) can be used without limitation, but anionic emulsifiers and / or nonionic emulsifiers are preferable, and anionic emulsifiers are particularly preferable. As the anionic emulsifier, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, alkylbenzene sulfonate and other sulfonates are suitable, and as nonionic emulsifier, polyoxyethylene alkyl ether and the like are suitable. is there. These emulsifiers can be used alone or in combination of two or more.

  By using the monoalkyl succinate sulfonate and other emulsifiers in such a specific mixing ratio (95: 5 to 70:30), the polymerization stability is further improved, and the polymer emulsion has better properties. (Acrylic emulsion) can be obtained. The compounding ratio of the monoalkyl succinate sulfonate and the other emulsifier is more preferably 95: 5 to 75:25 (weight ratio).

  In the present invention, the amount of the emulsifier is preferably about 0.3 to 5 parts by weight, more preferably about 0.5 to 3 parts by weight with respect to 100 parts by weight of the total monomer mixture. When the blending amount of the emulsifier exceeds 5 parts by weight with respect to 100 parts by weight of the total monomer mixture, the water resistance of the resulting pressure-sensitive adhesive tends to deteriorate and the adhesive properties tend to deteriorate. Emulsification may not be maintained, both of which are not preferred.

  In the present invention, the emulsion polymerization may be carried out in accordance with a normal emulsion polymerization method, except that the monoalkyl succinate sulfonate and other emulsifier are used in the above-mentioned blending ratio. The polymerization is carried out by any method such as polymerization or divided dropping polymerization. The polymerization temperature can be appropriately selected according to the type of the polymerization initiator, and can be selected from the range of 5 to 97 ° C, for example.

Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2). -Imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) dihydrochloride and other azo-based initiators; persulfate such as potassium persulfate and ammonium persulfate Peroxides such as benzoyl peroxide, t-butyl hydroperoxide, hydrogen peroxide; peroxides and reducing agents such as a combination of persulfate and sodium bisulfite, a combination of peroxide and sodium ascorbate; The redox initiator etc. which combined these are mentioned, However, It is not limited to these. Moreover, these can be used individually or in combination of 2 or more types. In particular, by using a persulfate such as potassium persulfate or ammonium persulfate as a polymerization initiator, a cross-linking reaction is caused between polymer chains during emulsion polymerization to form a gel.
The amount of these polymerization initiators can be appropriately selected depending on the type and the type of monomer, but usually selected from the range of, for example, about 0.01 to 1 part by weight per 100 parts by weight of the total monomer mixture. It is preferable to use in the range of 0.02 to 0.5 parts by weight.

  A chain transfer agent may be used to adjust the molecular weight of the polymer (acrylic polymer) to be obtained. The chain transfer agent is not particularly limited, but a conventional chain transfer agent such as lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, 2-ethylhexyl thioglycolate, 2,3-dimethylcapto- 1-propanol etc. are mentioned, 1 type (s) or 2 or more types are used according to a use. The amount of chain transfer agent used is usually about 0.001 to 0.3 parts by weight per 100 parts by weight of the total monomer mixture.

  The emulsion-type acrylic pressure-sensitive adhesive of the present invention comprises a polymer emulsion (acrylic emulsion) obtained by emulsion polymerization using the above monoalkyl succinate sulfonate and other emulsifier as an emulsifier, and is necessary for this. Accordingly, additives such as a crosslinking agent, a tackifier, a thickener, a dispersion stabilizer, a filler, and a colorant may be added thereto. The emulsion-type acrylic pressure-sensitive adhesive of the present invention does not use nonylphenol as an emulsifier, and thus has high safety, low skin irritation, and is particularly suitable as a medical pressure-sensitive adhesive, but is used as a medical pressure-sensitive adhesive. In this case, it is necessary to thoroughly examine these additives in terms of safety.

  The molecular weight characteristic of the polymer (acrylic polymer) in the emulsion-type acrylic pressure-sensitive adhesive of the present invention is appropriately determined according to the use of the pressure-sensitive adhesive, etc. For example, the pressure-sensitive adhesive of the present invention is used as a medical pressure-sensitive adhesive. In this case, the weight average molecular weight of the polymer sol is preferably 150,000 to 400,000, and particularly preferably 200,000 to 370,000. If the weight average molecular weight of the sol is less than 150,000, adhesive residue is left on the adherend, and if it exceeds 400,000, the skin adhesiveness can be maintained, but pain may occur when the adhesive tape is peeled from the skin surface. .

  The weight average molecular weight of the polymer sol in the emulsion type acrylic pressure-sensitive adhesive in the present invention is a value measured by gel permeation chromatography (GPC method). Specifically, about 1 g of pressure-sensitive adhesive is used. Soaked in 50 ml of toluene at room temperature for 1 week, filtered to remove the solvent-insoluble matter, dried sol-dissolved toluene solution, removed the solvent, and then prepared the residue to 1.0 g / l tetrahydrofuran solution and left to stand overnight To do. Thereafter, the solution was filtered through a 0.45 μm pore membrane filter, and the filtrate was measured as a polystyrene equivalent value by GPC method (analyzer: manufactured by TOSOH, HLC-8120GPC).

  An adhesive tape or sheet is obtained by forming an adhesive layer of the emulsion acrylic adhesive of the present invention on one or both sides of a tape-like or sheet-like substrate. Although the thickness of an adhesive layer can be suitably determined according to adhesive force etc., generally it is 100 micrometers or less, Preferably it is 20-80 micrometers. The pressure-sensitive adhesive layer may be formed by directly applying and drying an emulsion type acrylic pressure-sensitive adhesive on a base material, or may be formed by applying and drying on a release paper and then sticking to a base material. . In applying the adhesive to the substrate, a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater can be used.

  Various plastic films such as polyethylene, polypropylene, ethylene / vinyl acetate copolymer, polyester, polyvinyl chloride, and polyurethane, and woven fabrics, knitted fabrics, nonwoven fabrics, paper, metal foils, or these are laminated on the above-mentioned base material Things can be used. Although the thickness of a base material changes with materials, it is common to set it as about 10-1000 micrometers.

  The pressure-sensitive adhesive tape or sheet using the pressure-sensitive adhesive of the present invention can be used for various uses such as a tape or tack sheet, a double-sided tape as a general consumer goods, among them, suitable for medical use, hygiene material use, etc. It is particularly suitable for medical use. If it uses for these uses, there will be no restriction | limiting in particular in a shape, For example, it can process and use suitably for an emergency adhesive bandage, a wound adhesive bandage, a large-sized adhesive bandage, a dressing material, a drape material, etc.

  Hereinafter, the present invention will be described more specifically with reference to examples. The following are representative examples and are not limited to these, and various applications are possible without departing from the technical idea of the present invention. In the following, “parts” means all parts by weight.

[Example 1]
In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 180 parts of water, “New Coal 293” (manufactured by Nippon Emulsifier Co., Ltd.) as a monoalkyl succinate sulfonate type emulsifier (= general formula) (3) R ⁵ is C ₈ H ₁₇ , m is 2, X ¹ and X ² are each Na) 1 part and “Latemul E-118B” (manufactured by Kao) (= polyoxyethylene alkyl ether) Sodium sulfate) 0.06 part, monomer 2-ethylhexyl acrylate 75 parts, acrylic acid 5 parts, isobutyl acrylate 20 parts, chain transfer agent 0.06 parts lauryl mercaptan, polymerization temperature 60 ° C., 1 with stirring Nitrogen replacement was performed for a time. Thereafter, 0.2 part of ammonium persulfate dissolved in a small amount of water was added, and the mixture was further reacted for 1 hour.

  Here, 30 parts of water, 0.8 parts of “New Coal 293” (manufactured by Nippon Emulsifier Co., Ltd.) and “Latemul E-118B” (manufactured by Kao Corporation) (= polyoxyethylene) as an emulsifier of monoalkyl succinate sulfonate type Sodium alkyl ether sulfate) 0.2 parts, monomer as ethylhexyl acrylate 75 parts, acrylic acid 5 parts, isobutyl acrylate 20 parts, chain transfer agent lauryl mercaptan 0.06 parts, polymerization initiator 0.05 parts The resulting product was added dropwise to the preparation by an emulsion monomer split addition method and allowed to react for about 8 hours. Thereafter, a ripening reaction was performed at 80 ° C. for 1 hour to complete the polymerization reaction, and the emulsion-type pressure-sensitive adhesive of the present invention was obtained. The weight average molecular weight of the pressure-sensitive adhesive (polymer) was 280,000.

  This emulsion-type pressure-sensitive adhesive was applied to the treated surface of a 38 μm PET film or silicone release paper so that the thickness of the pressure-sensitive adhesive layer was 40 μm, and dried to prepare a pressure-sensitive adhesive tape.

[Examples 2 to 6]
Emulsion polymerization was carried out in the same manner as in Example 1 except that the monomer mixture composition and the amount of emulsifier were changed as shown in Table 1 below, to obtain the emulsion-type pressure-sensitive adhesive of the present invention. Table 1 also shows the composition of Example 1 for reference.

[Comparative Examples 1-5]
Except that the monomer mixture composition and the amount of the emulsifier were changed as shown in Table 1, five types of blending were performed in the same manner as in Example 1.

[Evaluation test]
(1) Polymerization stability With respect to the emulsions obtained in the examples and comparative examples, the state when taking out from the polymerization vessel was visually observed for the presence of gelation and blistering, and evaluated according to the following criteria.
○: Gelation did not occur during polymerization, and no fuzz occurred.
Separation: There was monomer separation during the middle of the polymerization.
Buzz: There was a buzz.
Gelation: Gelled during polymerization.

(2) Adhesive properties <Evaluation 1> Adhesiveness The dried adhesive tape was cut into a width of 12 mm, and the adhesive surface was pressure-bonded to a phenolic resin laminate with a 2 kg rubber roller. After 30 minutes, the stress when peeling at a speed of 300 mm / min was measured as the adhesive strength.
<Evaluation 2> Skin adhesiveness An adhesive tape cut to a width of 12 mm and a length of 70 mm was applied to the skin surface of the inner side of the forearm of a volunteer, and evaluation was performed according to the following evaluation criteria after 3 hours.
Skin adhesion ○: Feeling to adhere very strongly △: Feeling to adhere well ×: Feeling weak adhesion ○: Pain when peeling ○: Pain when peeling △: Pain when peeling ×: Pain when peeling

(3) Presence / absence of environmental hormones Each adhesive component was judged from catalogs and MSDS commercial data.

  In the table, New Coal 1305SN and Triton X301 are anionic emulsifiers, New Coal 1305SN is sodium polyoxyethylene tridecyl ether sulfate manufactured by Nippon Emulsifier Co., Ltd., Triton X301 is sodium octylphenoxy polyethoxyethyl sulfate manufactured by Dow Chemical Co., Ltd. is there.

  From the results of Table 1, according to the method for producing an emulsion-type acrylic pressure-sensitive adhesive of the present invention, a polymer emulsion (acrylic emulsion) can be produced with good polymerization stability without using nonylphenol, and good adhesion can be achieved. It can be seen that the emulsion-type acrylic pressure-sensitive adhesive having the characteristics can be easily produced. The emulsion-type acrylic pressure-sensitive adhesive of the present invention thus obtained exhibits a good pressure-sensitive adhesive property particularly to the skin (in vitro skin), so that it can be used for a medical pressure-sensitive adhesive tape or a pressure-sensitive adhesive layer for a sheet. It turns out that it is especially suitable.

Claims (7)

General formula (1): H ₂ C═C (R ¹ ) COOR ² [wherein R ¹ represents hydrogen or a methyl group, and R ² represents a C _{5 to} C ₁₂ alkyl group. 60 to 85% by weight of the first (meth) acrylic monomer represented by the general formula (2): H ₂ C═C (R ³ ) COOR ⁴ [wherein R ³ is hydrogen or a methyl group, R ⁴ represents a C _{1 to} C ₄ alkyl group. A monomer mixture containing 10 to 30% by weight of the second (meth) acrylic monomer represented by the formula (1) and 2 to 10% by weight of the carboxyl group-containing vinyl monomer, and a monoalkyl succinate sulfonate Emulsion polymerization in the presence of an emulsifier containing another emulsifier in a mixing ratio of 95: 5 to 70:30 (weight ratio).   The method for producing an emulsion-type acrylic pressure-sensitive adhesive according to claim 1, wherein the other emulsifier is an anionic emulsifier or / and a nonionic emulsifier.   The manufacturing method of the emulsion type acrylic adhesive of Claim 1 or 2 whose usage-amount of the emulsifier containing a monoalkyl succinate sulfonate and another emulsifier is 0.3-5 weight part per 100 weight part of monomers.   The emulsion-type acrylic adhesive manufactured by the method as described in any one of Claims 1-3.   The emulsion-type acrylic pressure-sensitive adhesive according to claim 4, wherein the weight average molecular weight of the polymer sol is 150,000 to 400,000.   The emulsion-type acrylic pressure-sensitive adhesive according to claim 4 or 5, which is for medical use.   The medical adhesive tape or sheet | seat which has the adhesion layer by the emulsion type acrylic adhesive as described in any one of Claims 4-6 on the at least single side | surface of a base material.