JP2009126872A - Acrylic emulsion composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic emulsion composition having a sufficiently long preservable period of time. <P>SOLUTION: The acrylic emulsion composition includes (A) a copolymer containing a structural unit derived from an acrylic or a methacrylic ester monomer, (B) 2-methyl-4-isothiazolin-3-one formulated in an amount of 1.0×10<SP>-3</SP>to 5.0×10<SP>-2</SP>pt.mass based on 100 pts.mass of (A) the copolymer, and (C) 2-n-octyl-4-isothiazolin-3-one formulated in an amount of 2.0×10<SP>-4</SP>to 1.0×10<SP>-2</SP>pt.mass based on 100 pts.mass of (A) the copolymer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acrylic emulsion composition. More specifically, the present invention relates to an acrylic emulsion composition that is resistant to spoilage and has excellent storage stability.

  Conventionally, adhesive labels, tapes, sheets and the like in which an adhesive layer is formed on one surface of a substrate such as paper are known. These pressure-sensitive adhesive layers such as labels, tapes, and sheets are formed with water-soluble adhesives, and many water-soluble adhesives are mainly composed of an acrylic emulsion. . For example, a pressure-sensitive adhesive composition in which an amphoteric surfactant and a plasticizer are blended in a copolymer emulsion (see, for example, Patent Document 1) has been reported.

Japanese Examined Patent Publication No. 62-47463

  However, in the composition described in Patent Document 1, bacteria, fungi, and the like (hereinafter sometimes referred to as “fungi”) propagated during long-term storage, resulting in deterioration and spoilage. When quality change or decay occurs, the viscosity is lowered or a strange odor is generated, so that there is a problem that the quality is remarkably impaired.

  The present invention has been made to solve the above-described problems of the prior art, and provides an acrylic emulsion composition that is resistant to spoilage and has a sufficiently long storage period, that is, excellent storage stability. To do.

  As a result of intensive studies to solve the above problems, the present inventors have included 2-methyl-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one in predetermined amounts. Therefore, the present invention has been completed by finding that the above problems can be solved because the effects of each other are exhibited synergistically, that is, the decrease of the compound over time is suppressed. It was.

  Specifically, the following acrylic emulsion composition is provided by the present invention.

[1] (A) (meth) and copolymers containing structural units derived from acrylic acid ester monomer, (B) the (A) the copolymer 100 parts by mass, 1.0 × 10 ^{- 3 to} 5.0 × 10 ⁻² parts by mass of 2-methyl-4-isothiazolin-3-one and (C) to 100 parts by mass of the (A) copolymer, 2.0 × 10 ⁻ An acrylic emulsion composition containing 2-n-octyl-4-isothiazolin-3-one blended with ^{4 to} 1.0 × 10 ⁻² parts by mass.

[2] The acrylic emulsion composition according to [1], wherein the (A) copolymer further includes a structural unit derived from an aromatic vinyl monomer.

[3] The blending ratio of (C) 2-n-octyl-4-isothiazolin-3-one and (B) 2-methyl-4-isothiazolin-3-one is ((C) :( B)). The acrylic emulsion composition according to [1] or [2], wherein the mass ratio is 1: 2 to 1:50.

  The acrylic emulsion composition of the present invention contains 2-methyl-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one in a predetermined amount so that the effects of each other are synergistic. Therefore, it has the effect of being resistant to spoilage and being excellent in long-term storage stability.

  Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited to the following embodiment. That is, it is understood that modifications and improvements as appropriate to the following embodiments are also within the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

[1] Acrylic emulsion composition:
One embodiment of the acrylic emulsion composition of the present invention is a copolymer containing a structural unit derived from (A) (meth) acrylic acid ester monomer (hereinafter sometimes referred to as “component (A)”). And (B) 2-methyl-4-isothiazolin-3-one blended in an amount of 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² parts by mass with respect to 100 parts by mass of the (A) copolymer. (Hereinafter, may be referred to as “component (B)”) and (C) 2.0 × 10 ^{−4 to} 1.0 × 10 ⁻² mass relative to 100 parts by mass of the (A) copolymer. 2-n-octyl-4-isothiazolin-3-one (hereinafter may be referred to as “component (C)”) that is partially blended.

  Thus, the acrylic emulsion of this embodiment is obtained by combining 2-methyl-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one in respective predetermined amounts. Since the composition contains 2-methyl-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one, the composition is hardly spoiled and has excellent storage stability. In addition, it is possible to prevent the viscosity of the acrylic emulsion from being lowered due to the decomposition of the component (A) by bacteria, mold, etc. during storage.

[2] Component (A):
The component (A) contained in the acrylic emulsion composition of this embodiment is a copolymer containing a structural unit derived from a (meth) acrylic acid ester. Thus, since (A) component contains the structural unit derived from (meth) acrylic acid ester, when using as an adhesive agent, for example, it exhibits favorable adhesiveness.

  As (meth) acrylic acid ester for constituting the structural unit derived from (meth) acrylic acid ester, for example, 2-ethylhexyl acrylate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n -Butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, amyl acrylate, amyl methacrylate, isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, isononyl acrylate, isononyl Methacrylate, lauryl acrylate, lauryl methacrylate, glycidyl acrylate Glycidyl monomers such as glycidyl methacrylate, beta-hydroxyethyl acrylate, beta-hydroxyethyl methacrylate, beta-hydroxypropyl acrylate and beta-hydroxypropyl methacrylate or the like. Among these, 2-ethylhexyl acrylate and n-butyl acrylate are preferable. When 2-ethylhexyl acrylate or n-butyl acrylate is used, the glass transition point of the component (A) to be obtained is lowered, so that there is an advantage that the adhesive strength and tack are improved. In addition, these (meth) acrylic acid ester can be used individually or in mixture of 2 or more types.

  The content of the structural unit derived from the (meth) acrylic acid ester is preferably 80 to 99% by mass, more preferably 85 to 99% by mass, and more preferably 90 to 98% by mass with respect to all the structural units. % Is particularly preferred. There exists a possibility that adhesive force and tack may fall that the said content rate is less than 80 mass%. On the other hand, if it exceeds 99% by mass, the cohesive force may be reduced.

  The component (A) is preferably a copolymer containing a structural unit derived from an aromatic vinyl monomer. By including a structural unit derived from an aromatic vinyl monomer, the component (A) exhibits even better adhesiveness when used as an adhesive.

  Examples of the aromatic vinyl monomer for constituting the structural unit derived from the aromatic vinyl monomer include styrene, α-methylstyrene, styrenesulfonic acid, and sodium salts thereof. Among these, styrene and α-methylstyrene are preferable. When it is styrene or α-methylstyrene, there is an advantage that the cohesive force of the obtained component (A) is improved. In addition, these aromatic vinyl monomers can be used individually or in mixture of 2 or more types.

  The content of the structural unit derived from the aromatic vinyl monomer is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, based on the total structural unit. It is particularly preferably 0.5 to 3% by mass. When the content is less than 0.1% by mass, the cohesive force may be reduced. On the other hand, if it exceeds 10% by mass, the adhesive strength and tack may be reduced.

  The component (A) can further contain structural units derived from other monomers in addition to the structural units derived from the (meth) acrylic acid ester and the structural units derived from the aromatic vinyl monomer. .

  The other monomer for constituting the structural unit derived from the other monomer is not particularly limited as long as it is copolymerizable with the above (meth) acrylic acid ester and the above aromatic vinyl monomer. Are, for example, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, ethylenically unsaturated carboxylic acid monomers such as itaconic acid, acrylic acid, methacrylic acid and fumaric acid, and amide based monomers such as acrylamide and methacrylamide. Examples include a polymer. Among these, acrylonitrile, acrylamide, methacrylamide, acrylic acid, and methacrylic acid are preferable. Acrylonitrile, acrylamide, methacrylamide, acrylic acid, and methacrylic acid have the advantage of improving cohesion. In addition, these other monomers can be used individually or in mixture of 2 or more types.

  The content of structural units derived from other monomers is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on all structural units, and 0 It is particularly preferably 5 to 3% by mass. When the content is less than 0.1% by mass, the cohesive force may be reduced. On the other hand, if it exceeds 10% by mass, the adhesive strength and tack may be reduced.

  The component (A) contained in the acrylic emulsion composition of the present embodiment includes (meth) acrylic acid ester, aromatic vinyl compound, and other monomers as necessary (hereinafter referred to as “single amount”). Is obtained by emulsifying the resulting mixture in water with an emulsifier, and polymerizing the resulting pre-emulsion with a polymerization initiator and a molecular weight regulator in an inert atmosphere. It can be obtained in a state dispersed in an emulsion.

  As the emulsifier, surfactants such as polyoxyethylene nonylphenyl ether, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and the like can be used. The use ratio of the emulsifier is preferably 0.2 to 7% by mass, more preferably 0.5 to 5% by mass, and 0.7 to 5% by mass with respect to the monomer mixture. It is particularly preferred. There exists a possibility that mechanical stability may fall that the said usage rate is less than 0.2 mass%. On the other hand, if it exceeds 7% by mass, tack may be lowered. By appropriately selecting the type and use ratio of the emulsifier, an emulsion containing the component (A) having a number average particle size of a target size can be obtained. The emulsion polymerization temperature is preferably 5 to 85 ° C, more preferably 35 to 80 ° C.

  As the polymerization initiator, persulfate, azobisisobutyronitrile, peroxides and the like can be used. The use ratio of the polymerization initiator is preferably 0.01 to 5% by mass, more preferably 0.05 to 3% by mass, and 0.1 to 1% by mass with respect to the monomer mixture. It is particularly preferred that There exists a possibility that reaction activity may fall that the said usage rate is less than 0.01 mass%. On the other hand, if it exceeds 5% by mass, it may be difficult to control the particle size.

  As the molecular weight regulator, butyl mercaptan, dodecyl mercaptan, octyl thioglycolate, isopropyl alcohol, methanol, carbon tetrachloride and the like can be used. These molecular weight regulators can be used alone or in combination of two or more. The use ratio of the molecular weight regulator is preferably 0.001 to 0.5% by mass, more preferably 0.003 to 0.3% by mass with respect to the monomer mixture, and 0.005 It is especially preferable that it is -0.1 mass%. There exists a possibility that adhesive force may fall that the said usage rate is less than 0.001 mass%. On the other hand, if it exceeds 0.5 mass%, the cohesive force may be reduced. By appropriately selecting the type and use ratio of the molecular weight regulator, an emulsion containing the component (A) having a number average molecular weight of a desired size can be obtained. In addition, additives, such as an antifoamer, a thickener, and antiseptic | preservative, can be added to the said pre-emulsion as needed.

  The polymerization treatment can be performed by various means, but it is preferable to complete the polymerization reaction of the monomer mixture while supplying the pre-emulsion to the reactor continuously or intermittently. In addition, it is preferable that the polymerization conversion rate in emulsion polymerization is 99-100 mass%.

  The component (A) contained in the acrylic emulsion composition of the present embodiment preferably has a glass transition temperature of −90 to −50 ° C., more preferably −80 to −60 ° C. There exists a possibility that adhesive force and tack may fall that the said glass transition temperature is less than -90 degreeC. On the other hand, if it exceeds -50 ° C, the cohesive force may be reduced.

  Here, in this specification, “glass transition temperature” refers to a differential scanning calorific value of a film produced by an emulsion containing the component (A), vacuum-dried at 50 ° C. for 2 hours, and dried. It is the value measured according to ASTM method using a meter. As an apparatus for measuring the glass transition temperature, for example, “DSC-6200 type” manufactured by SII Nanotechnology Inc. can be used.

  The component (A) contained in the acrylic emulsion composition of the present embodiment preferably has a number average particle size of 100 to 500 nm, more preferably 150 to 450 nm, and 180 to 400 nm. Is particularly preferred. If the number average particle diameter is less than 100 nm, the mechanical stability may be lowered. On the other hand, when the number average particle diameter is more than 500 nm, the adhesion may be lowered. Here, “number average particle diameter” in the present specification is a value measured by a light scattering method. As an apparatus for measuring the number average particle diameter, for example, a concentrated particle size analyzer “FPAR-1000” manufactured by Otsuka Electronics Co., Ltd. can be used.

[3] Component (B):
Component (B) contained in the acrylic emulsion composition of the present embodiment is 2-methyl-4-isothiazolin-3-one, and this 2-methyl-4-isothiazolin-3-one is 1.0 * 10 < ^-3 > -5.0 * 10 ^<-2 > mass part is mix | blended with respect to 100 mass parts of polymers ((A) component). (B) component has the effect | action which suppresses reproduction of bacteria, mold, etc.

The blending amount of 2-methyl-4-isothiazolin-3-one is 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² parts by mass with respect to 100 parts by mass of component (A), and 2.0 is preferably × ¹⁰ -3 ~4.0 × ^{10 -2} parts by mass, further preferably 4.0 × ¹⁰ -3 ~3.0 × ^{10 -2} parts by weight. When the blending amount is less than 1.0 × 10 ⁻³ parts by mass, the antiseptic effect is not sufficiently obtained and the bacteria propagate and the acrylic emulsion is spoiled. On the other hand, if it exceeds 5.0 × 10 ⁻² parts by mass, the acrylic emulsion is likely to be foamed and difficult to handle.

[4] Component (C):
The component (C) contained in the acrylic emulsion composition of this embodiment is 2-n-octyl-4-isothiazolin-3-one, and this 2-n-octyl-4-isothiazolin-3-one is (A) 2.0 * 10 ^{< -4} > -1.0 * 10 ^<-2 > mass part is mix | blended with respect to 100 mass parts of copolymers ((A) component). The component (C) has an action of sterilizing bacteria, molds and the like.

The compounding quantity of 2-n-octyl-4-isothiazolin-3-one is 2.0 * 10 ^{< -4} > -1.0 * 10 ^<-2 > mass part with respect to 100 mass parts of (A) component, 3 It is preferably 0.0 × 10 ^{−4 to} 0.8 × 10 ⁻² parts by mass, and more preferably 4.0 × 10 ^{−4 to} 0.7 × 10 ⁻² parts by mass. If the blending amount is less than 2.0 × 10 ⁻⁴ parts by mass, mold grows on the acrylic emulsion being stored. On the other hand, if it exceeds 1.0 × 10 ⁻² parts by mass, the acrylic emulsion is likely to be foamed and difficult to handle.

  The acrylic emulsion composition of the present embodiment contains the component (A), and a predetermined amount of 2-methyl-4-isothiazolin-3-one and a predetermined amount of 2-n-octyl-4-isothiazoline- It is characterized by using in combination with 3-one. That is, since the component (B) has a good effect of suppressing the growth of bacteria and molds present in the acrylic emulsion composition, the antiseptic effect for a long period of time is maintained. Accordingly, it is possible to suppress the occurrence of malodor and rot associated with discoloration of the acrylic emulsion composition. Since the component (C) can sterilize bacteria and molds in the acrylic emulsion composition and on the surface of the acrylic emulsion composition exposed to the atmosphere, it can prevent the growth of bacteria and molds. Moreover, by using together (B) component and (C) component, an antiseptic effect and a bactericidal effect are exhibited synergistically, compared with the case where (B) component or (C) component is used independently, for a long period of time. There is an advantage that it can be stored.

  By the way, heretofore, styrene-butadiene copolymers have been added to 1,2-benzothiazolone-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and 2-methyl-4-isothiazolin-3-one. A composition obtained by adding these is known (for example, Japanese Patent Publication No. 7-037362). However, this composition has not only a sufficient shelf life, but also contains component (A), 1,2-benzothiazolone-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one And the composition obtained by mixing 2-methyl-4-isothiazolin-3-one has a problem that the antiseptic effect decreases during storage because each active ingredient in the composition is decomposed during storage. was there.

  On the other hand, 2-methyl-4-isothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one blended in the acrylic emulsion composition of the present invention are difficult to decompose during storage, that is, Since it is difficult to decrease over time, it is difficult to suppress the propagation of bacteria for a long period of time, and it is difficult to cause quality deterioration due to spoilage. Therefore, even after the acrylic emulsion composition of the present invention has been stored for a long period of time, it can be used favorably as, for example, an adhesive layer such as an adhesive label, tape, or sheet.

  The blending ratio ((C) :( B)) of the component (C) and the component (B) is preferably 1: 1 to 1:40, and preferably 1: 3 to 1:20 in terms of mass ratio. Is more preferable, and 1: 6 to 1:15 is particularly preferable. When the blending ratio is less than 1 part by mass with respect to 1 part by mass of component (C), the acrylic emulsion being stored may be spoiled. On the other hand, if the component (B) exceeds 40 parts by mass with respect to 1 part by mass of the (C) component in the above blending ratio, the effect of the (C) component is impaired, and mold may be generated in the acrylic emulsion during storage. There is.

  In addition, as a commercial item containing (B) component and (C) component, "Roshima 553" etc. by Rohm and Haas Japan can be mentioned, for example.

[5] Other fungicides and preservatives:
In the acrylic emulsion composition of the present embodiment, in addition to the components (B) and (C), 2-bromo-2-nitrilopropane-1,3-diol (bronopol), 2,2-dibromo-3-nitrilo Bactericides such as propionamide, 2-mercaptopyridine-N-oxide Na salt, aqueous hydrogen peroxide, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazoline-3one, bromonitro Preservatives such as alcohol and chloroacetamide can be used. Among these, 2-bromo-2-nitrilopropane-1,3-diol and 5-chloro-2-methyl-4-isothiazolin-3-one are preferable, and long-term storage becomes possible by using these. There is an advantage.

[6] Other additives:
In addition to the components (A) to (C) and other bactericides and preservatives, the acrylic emulsion composition of the present embodiment can contain additives such as stabilizers (other additives). Examples of the stabilizer include an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. These can be used alone or in combination of two or more.

  Furthermore, the acrylic emulsion composition of the present embodiment can contain polyethylene glycol, dipropylene glycol, sodium polyacrylate, polyacrylamide, sodium tripolyphosphate, and the like.

  The acrylic emulsion composition of the present embodiment preferably has a pH of 5.0 to 12.0, more preferably 6.0 to 10.0, and 6.5 to 9.5. Particularly preferred. There exists a possibility that mechanical stability may fall that the said pH is less than 5.0. On the other hand, if the pH is more than 12.0, the viscosity becomes high and workability may be reduced.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. The glass transition temperature and the number average particle diameter in Examples and Comparative Examples were measured by the following methods.

[Glass-transition temperature]:
(A) After forming a thin film with the emulsion containing a component, it vacuum-dried at 50 degreeC for 2 hours, and produced the film. About this film, the glass transition temperature was measured according to ASTM method using the differential scanning calorimeter ("DSC-6200 type | mold", the SII nanotechnology company make).

[Number average particle diameter]:
The number average particle size of the component (A) was measured with a concentrated particle size analyzer “FPAR-1000” manufactured by Otsuka Electronics.

(Example 1)
First, a monomer mixture consisting of 94 parts of 2-ethylhexyl acrylate, 3 parts of acrylonitrile, 1 part of acrylic acid, and 2 parts of N-methylolacrylamide was prepared. Next, 40 parts of water and 0.4 part of sodium persulfate as a polymerization initiator were charged in an autoclave equipped with a stirrer, a temperature controller and a reflux condenser, and the temperature was raised to 70 ° C. In this autoclave, 100 parts of the above monomer mixture, 0.02 part of n-butyl mercaptan as a molecular weight regulator, 1 part of sodium dodecylbenzenesulfonate as an emulsifier, 1 part of polyoxyethylene alkyl ether, 60 parts of water And pre-emulsion was prepared by stirring and emulsifying. The prepared pre-emulsion was taken out from the autoclave, and the whole amount was continuously fed into another autoclave at 80 ° C. over 3 hours and stirred, and then stirred at 80 ° C. for 2.5 hours to conduct a polymerization reaction. Thus, a copolymer (((a structural unit derived from 2-ethylhexyl acrylate, a structural unit derived from acrylonitrile, a structural unit derived from acrylic acid, and a structural unit derived from N-methylolacrylamide) ( An emulsion (acrylic emulsion) containing (A) a copolymer) was obtained. The resulting acrylic emulsion had a solid content of 50%, the copolymer had a number average particle size of 300 nm, and a glass transition temperature of -64 ° C. The formulation is shown in Table 1.

For 100 parts of the resulting acrylic emulsion (solid content), 2-methyl-4-isothiazolin-3-one (product “Codec 50C”, manufactured by Rohm and Haas Japan Co., Ltd.) is used as component (B). 400 × ^{10 -4} parts, and (C) 2-n-octyl-4-isothiazolin-3-one as the component (product "Rebanakkusu BS-50" Shoei chemical Co., Ltd.) was added 10 × ^{10 -4} parts An acrylic emulsion composition was prepared. The acrylic emulsion composition thus prepared was evaluated for bactericidal and abuse tests by the methods shown below.

[Bactericidal]
The acrylic emulsion composition obtained in the present embodiment, as the number of bacteria after the addition of 10 ⁷ cells / ml, was added and bacterial liquid, after placed in 48 hours, 40 ° C., the acrylic emulsion composition The number of bacteria was measured to evaluate bactericidal properties. In addition, the bacterial emulsion used in advance was an acrylic emulsion composition in which commonas acidovorans was added to the obtained acrylic emulsion composition as an indicator bacterium and was spoiled to obtain a predetermined number of bacteria. Evaluation criteria where the number of bacteria is less than 10 ³ cells / ml and a "○", the case where the number of bacteria is less than ¹⁰⁵ cells / ml in 10 ³ cells / ml or more as "△", the number of bacteria The case of exceeding 10 ⁵ pieces / ml was designated as “x”. The number of bacteria was measured by culturing in a thermostat at 28 ° C. for 48 hours using a commercially available “Easycult TTC” (manufactured by Orion Diagnostics: Finland) and then observing the number of colonies.

[Abuse test]
The acrylic emulsion composition 100g obtained in this example, using Comamonas acidovorans as an indicator bacterium, the number of bacteria was added repetition of 10 ⁷ / ml acrylic emulsion 20g every week. After the addition, the number of bacteria in the acrylic emulsion composition was measured 48 hours later, and the abuse test was evaluated. The evaluation criteria are “○” when the number of bacteria after repeated addition 5 times (after 5 weeks) is 102 ² / ml or less, and the number of bacteria after 2-4 times (after 2-4 weeks) There was a "△" a case where 10 ² cells / ml or less, and the case where the number of bacteria once (after 1 week) of 10 ² cells / ml or more as "×". The number of bacteria was measured in the same manner as the evaluation of [bactericidal].

  The acrylic emulsion composition of this example had a bactericidal evaluation of ◯ and an abuse test of ◯.

(Examples 2-4, Comparative Examples 1-4)
An acrylic emulsion composition was prepared in the same manner as in Example 1 except that the formulation shown in Table 2 was used, and the prepared acrylic emulsion composition was evaluated for bactericidal properties and abuse tests.

  The acrylic emulsion compositions of Examples 1 to 4 were all confirmed to be excellent in bactericidal properties and abuse tests. On the other hand, the acrylic emulsion composition of Comparative Example 1 was confirmed to be inferior in bactericidal and abuse test results because the addition amount of the component (B) and the component (C) was outside the predetermined range. The acrylic emulsion compositions of Comparative Examples 2 and 3 are those in which the component (B) and the component (C) are used alone, and the acrylic emulsion composition of Comparative Example 2 is inferior in the abuse test. It was confirmed that the acrylic emulsion composition was inferior in bactericidal properties. Since the acrylic emulsion composition of Comparative Example 4 added components other than the component (B) and the component (C), it was confirmed that the results of the abuse test were inferior.

  As is clear from Table 2, the acrylic emulsion compositions of Examples 1 to 4 are less susceptible to decay than the acrylic emulsion compositions of Comparative Examples 1 to 4, and can be stored for a sufficient period. did it.

  The acrylic emulsion composition of the present invention can be suitably used as a material for forming an adhesive layer such as a label, tape, or sheet provided with an adhesive layer.

Claims (3)

(A) a copolymer containing a structural unit derived from a (meth) acrylic acid ester monomer;
(B) 2-methyl-4-isothiazolin-3-one blended in an amount of 1.0 × 10 ^{−3 to} 5.0 × 10 ⁻² parts by mass with respect to 100 parts by mass of the copolymer (A);
(C) 2-n-octyl-4-isothiazolin-3-one blended in an amount of 2.0 × 10 ^{−4 to} 1.0 × 10 ⁻² parts by mass with respect to 100 parts by mass of the copolymer (A). When,
An acrylic emulsion composition containing   The acrylic emulsion composition according to claim 1, wherein the copolymer (A) further comprises a structural unit derived from an aromatic vinyl monomer.   The mixing ratio ((C) :( B)) of the (C) 2-n-octyl-4-isothiazolin-3-one and the (B) 2-methyl-4-isothiazolin-3-one is a mass ratio. The acrylic emulsion composition according to claim 1 or 2, wherein the ratio is 1: 2 to 1:50.