JP2013001865A - Water-based self-adhesive composition and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique relating to a self-adhesive having both high water resistance and high adhesive force.SOLUTION: There is provided a water-based self-adhesive composition comprising a copolymerized dispersion which is produced by the emulsion polymerization of (a) 0.1-10 pts.mass of an ethylenically unsaturated carboxylic acid monomer, (b) 60-99 pts.mass of an acrylic acid ester monomer having a 4-12C alkyl group, and (c) 0-39.9 pts.mass of an ethylenically unsaturated monomer [wherein (a)+(b)+(c)=100 pts.mass] in a reaction system containing 0.1-10 pts.mass of a water-insoluble tackifier having an average particle diameter of 0.05-1.00 μm, wherein particles contained in the copolymerized dispersion have an average particle diameter of 0.3-10 μm, the glass transition point of the copolymerized dispersion is -70 to -30°C, and the insoluble content in a solution prepared by dissolving the copolymerized dispersion in tetrahydrofuran is ≤70 mass%.

Description

  The present invention relates to an aqueous pressure-sensitive adhesive composition and a method for producing the same.

  Adhesives are classified into many types, and performances such as adhesive strength, holding power, heat resistance, moist heat resistance, and water resistance are different for each type of adhesive. Among them, acrylic adhesives have a wide range of uses because they are excellent in adhesive strength and holding power. The acrylic pressure-sensitive adhesive can be obtained by emulsion polymerization of an acrylic monomer or the like. In particular, in order to further increase the adhesive strength of an acrylic pressure-sensitive adhesive, a technique for including a tackifier (tackifier resin) in a reaction system for emulsion polymerization has been proposed (for example, Patent Documents 1 to 3).

  These proposed technologies include emulsion polymerization using a large amount of polyoxyethylene rosin ester emulsifier, or emulsion polymerization by dissolving the tackifier in the monomer and finely dispersing the emulsion droplets with a high-pressure homogenizer. An acrylic pressure-sensitive adhesive is obtained by a method (so-called miniemulsion polymerization).

JP-A-8-301950 JP 2001-348551 A JP 2003-327933 A

  However, it is difficult to increase both the water resistance and the adhesive strength with the proposed technique described above. Further, the proposed technique is inferior in productivity because it requires a complicated process of dissolving the tackifier in the monomer by emulsion polymerization and further dispersing it.

  In view of the above problems, an object of the present invention is to provide a technique related to an adhesive having both high water resistance and high adhesive strength.

  According to the present invention, the above-described object can be achieved. The present invention is the following pressure-sensitive adhesive composition and method for producing the same.

[1] (a) 0.1 to 10 parts by mass of an ethylenically unsaturated carboxylic acid monomer, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group, and (c) 0 to 39.9 parts by mass of an ethylenically unsaturated monomer [provided that (a) + (b) + (c) = 100 parts by mass) is water-insoluble with an average particle size of 0.05 to 1.00 μm. It contains a copolymer dispersion obtained by emulsion polymerization in a reaction system containing 0.1 to 10 parts by mass of a tackifier, and the average particle size of the particles contained in the copolymer dispersion is 0.3 to 10 μm The copolymer dispersion is a water-based pressure-sensitive adhesive composition having a glass transition point of −70 to −30 ° C. and an insoluble content of 70% by mass or less when dissolved in tetrahydrofuran.

[2] The water-based pressure-sensitive adhesive composition according to [1], which contains a crosslinking agent.

[3] In a dispersion in which 0.1 to 10 parts by weight of a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm is dispersed in a medium, (a) an ethylenically unsaturated carboxylic acid monomer 0 0.1 to 10 parts by mass, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms of the alkyl group, and (c) 0 to 39.9 parts by mass of an ethylenically unsaturated monomer [provided that , (A) + (b) + (c) = 100 parts by mass], and a method for producing an aqueous pressure-sensitive adhesive composition by obtaining a copolymer dispersion by emulsion polymerization.

[4] (a) 0.1 to 10 parts by mass of an ethylenically unsaturated carboxylic acid monomer, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group, and (c) In the pre-emulsion containing 0 to 39.9 parts by mass of an ethylenically unsaturated monomer [where (a) + (b) + (c) = 100 parts by mass], a medium and an emulsifier, an average particle size of 0.05 The manufacturing method of the water-based adhesive composition which obtains a copolymer dispersion by adding 0.1-10 mass parts of water-insoluble tackifier of -1.00 micrometer, and carrying out emulsion polymerization.

[5] The method for producing an aqueous pressure-sensitive adhesive composition according to [3] or [4], wherein a crosslinking agent is added to the copolymer dispersion.

  The aqueous pressure-sensitive adhesive composition of the present invention has both high water resistance and high adhesive strength. The manufacturing method of the water-based pressure-sensitive adhesive composition of the present invention can provide a water-based pressure-sensitive adhesive composition having both high water resistance and high adhesive strength through simple steps.

  Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the present invention.

  The water-based pressure-sensitive adhesive composition of the present invention comprises (a) 0.1 to 10 parts by mass of an ethylenically unsaturated carboxylic acid monomer and (b) 60 to 60 acrylate monomers having 4 to 12 carbon atoms in the alkyl group. 99 parts by mass and (c) 0-39.9 parts by mass of an ethylenically unsaturated monomer [provided that (a) + (b) + (c) = 100 parts by mass)] It contains a copolymer dispersion obtained by emulsion polymerization in a reaction system containing 0.1 to 10 parts by weight of a 1.00 μm water-insoluble tackifier. Furthermore, in the water-based pressure-sensitive adhesive composition of the present invention, the copolymer dispersion has a glass transition point of −70 to −30 ° C. and an insoluble content of 70% by mass or less when dissolved in tetrahydrofuran. Moreover, in the aqueous adhesive composition of this invention, the average particle diameter of the particle | grains contained in a copolymer dispersion is 0.3-10 micrometers.

  The copolymer dispersion referred to in the present specification is an acrylic copolymer particle or a water-insoluble tackifier particle obtained by copolymerizing the component (a), the component (b), and the component (c). Or particles made of an acrylic copolymer and a water-insoluble tackifier are dispersed in a medium (for example, water).

  Here, the average particle size of the particles contained in the copolymer dispersion is an acrylic copolymer particle, a water-insoluble tackifier particle, or a particle comprising an acrylic copolymer and a water-insoluble tackifier. Mean particle diameter when all particles contained in the copolymer dispersion are measured. Moreover, the average particle diameter of the particle | grains contained in the copolymer dispersion as used in this specification means the volume average particle diameter measured by laser diffraction and scattering.

  The aqueous pressure-sensitive adhesive composition of the present invention has good stability and drying properties when the average particle size of the particles contained in the copolymer dispersion is 0.3 to 10 μm. In particular, the water-based pressure-sensitive adhesive composition of the present invention has an average particle size of 0.5 to 5.0 μm from the copolymer dispersion from the viewpoint that appropriate viscosity and high water resistance can be expressed. It is preferable that it is 1.0-3.0 micrometers. When the average particle size of the average particle size of the particles contained in the copolymer dispersion is 0.3 μm or more, the viscosity is not high, and therefore the solid content can be increased. When the average particle size of the particles contained in the copolymer dispersion is 10 μm or less, the viscosity is not too low and an appropriate viscosity is obtained.

  In the aqueous pressure-sensitive adhesive composition of the present invention, a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm is contained in the emulsion polymerization reaction system for obtaining a copolymer dispersion. The copolymerization reaction proceeds using the water-insoluble tackifier particles as seeds.

  In the water-based pressure-sensitive adhesive composition of the present invention, the copolymer dispersion has a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm and 0.1 to 10 parts by weight [provided that (a) an ethylenically unsaturated carboxylic acid Emulsion reaction in a reaction system comprising an acid monomer, (b) an acrylic acid ester monomer having 4 to 12 carbon atoms in an alkyl group, and (c) the total amount of ethylenically unsaturated monomers is 100 parts by mass] By being obtained, it becomes what has high adhesive force and high water resistance.

  In particular, as in the case of the water-based pressure-sensitive adhesive composition of the present invention, when the water-insoluble tackifier contains 0.1 parts by mass or more in the emulsion polymerization reaction system for obtaining the copolymer dispersion, the water-based pressure-sensitive adhesive The adhesive strength of the composition becomes sufficiently high. When the emulsion polymerization reaction system for obtaining the copolymer dispersion contains 10 parts by mass or less of the water-insoluble tackifier, as in the aqueous adhesive composition of the present invention, the aqueous adhesive composition Water resistance is sufficiently high.

  In the water-based pressure-sensitive adhesive composition of the present invention, the amount of the water-insoluble tackifier contained in the reaction system of the emulsion polymerization for obtaining the copolymer dispersion is from the viewpoint of improving both the adhesive strength and the water resistance. It is preferable that it is 1.0-5.0 mass parts.

  Moreover, the water-based pressure-sensitive adhesive composition of the present invention has an average particle diameter of the water-insoluble tackifier contained in the emulsion polymerization reaction system for obtaining a copolymer dispersion of 0.05 to 1.00 μm. The water-insoluble tackifier is easily dispersed during emulsion polymerization. Therefore, even when 0.1 to 10 parts by mass of a water-insoluble tackifier is present in the reaction system for emulsion polymerization, stability during polymerization is good and inhibition of the copolymerization reaction can be suppressed.

  In the emulsion polymerization for obtaining the copolymer dispersion, the water-insoluble tackifier may be preliminarily dispersed in a medium (for example, water) or may be added to a pre-emulsion containing a monomer. . The copolymer dispersion obtained by emulsion polymerization of such a technique gives high tackiness and high water resistance to the aqueous pressure-sensitive adhesive composition of the present invention.

  In addition, in the water-based pressure-sensitive adhesive composition of the present invention, in order to obtain the dispersion stability of the water-insoluble tackifier and obtain a copolymer dispersion from the viewpoint that the acrylic copolymer has an appropriate average particle size. It is preferable that the average particle diameter of the water-insoluble tackifier contained in the emulsion polymerization reaction system is 0.10 to 0.80 μm.

  The average particle diameter of the water-insoluble tackifier referred to in this specification means a volume average particle diameter measured by a laser diffraction / scattering method.

  The aqueous pressure-sensitive adhesive composition of the present invention is subjected to a copolymerization reaction for obtaining a copolymer dispersion (a) an ethylenically unsaturated carboxylic acid monomer and (b) an alkyl group having 4 to 4 carbon atoms. The amount of (a) the ethylenically unsaturated carboxylic acid monomer is 0.1 to 10 parts by mass with respect to 100 parts by mass of the total of 12 acrylate monomers and (c) the ethylenically unsaturated monomer. As a result, the adhesive strength and water resistance are sufficiently enhanced.

  Moreover, the water-based pressure-sensitive adhesive composition of the present invention has improved anchoring properties and adhesive strength when the glass transition point of the copolymer dispersion is -70 to -30 ° C.

  The (a) ethylenically unsaturated carboxylic acid monomer that can be used in the aqueous pressure-sensitive adhesive composition of the present invention refers to α, β unsaturated carboxylic acid. For example, examples of the (a) ethylenically unsaturated carboxylic acid monomer that can be used in the aqueous pressure-sensitive adhesive composition of the present invention include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and mono [2- Examples include half ester bodies such as (meth) acryloyloxyethyl], succinic acid mono [2- (meth) acryloyloxyethyl], carboxyethyl acrylate, and the like. These ethylenically unsaturated carboxylic acid monomers can be used alone or in combination of two or more. Among the ethylenically unsaturated carboxylic acid monomers listed here, it is preferable to use acrylic acid or methacrylic acid in the present invention from the viewpoint of improving the stability during polymerization and improving water resistance.

  Examples of the (b) acrylate monomer having 4 to 12 carbon atoms of the alkyl group that can be used in the aqueous pressure-sensitive adhesive composition of the present invention include n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, and 2-ethylhexyl. Examples include acrylate, n-octyl acrylate, isononyl acrylate, and lauryl acrylate. Among the acrylic acid ester monomers having 4 to 12 carbon atoms of the alkyl groups mentioned here, 2-ethylhexyl acrylate, n-octyl acrylate, and isononyl acrylate are used in the present invention from the viewpoint of enhancing adhesive strength and water resistance. It is preferable to use for.

  The (c) ethylenically unsaturated monomer that can be used in the aqueous pressure-sensitive adhesive composition of the present invention includes (a) an ethylenically unsaturated carboxylic acid monomer and (b) an acrylic acid having 4 to 12 carbon atoms in the alkyl group. A monomer copolymerizable with an ester monomer.

  For example, the (c) ethylenically unsaturated monomer that can be used in the aqueous pressure-sensitive adhesive composition of the present invention includes carbon atoms of alkyl groups such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate, and isopropyl methacrylate. Acrylic acid alkyl ester or methacrylic acid alkyl ester having 3 or less; (meth) acrylic acid cyclic alkyl ester such as cyclohexyl (meth) acrylate; aromatic (meth) acrylic such as phenoxymethyl (meth) acrylate and benzyl (meth) acrylate Acid ester; hydroxyalkyl acrylate, hydroxyalkyl methacrylate, polyoxyethylene (meth) acrylate, methoxyethyl acrylate, ethoxymethyl acrylate, glycy Aliphatic (meth) acrylic acid esters such as polyacrylate and glycidyl methacrylate; (meth) acrylic acid amides such as acrylamide, methacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-methoxybutylacrylamide; vinyl methyl ketone, Vinyl ethyl ketone, vinyl-n-propyl ketone, vinyl-i-propyl ketone, vinyl-n-butyl ketone, vinyl-i-butyl ketone, vinyl-t-butyl ketone, vinyl phenyl ketone, vinyl benzyl ketone, divinyl ketone, diacetone acrylamide Aldo group and / or keto group-containing radical polymerizable monomers such as: (meth) acrylonitrile, crotonnitrile, 2-cyanoethyl (meth) acrylate, 2-cyanopropyl ( Nitrile group-containing unsaturated compounds such as acrylate and 3-cyanopropyl (meth) acrylate; styrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene, p-ethylvinylstyrene, α-methylstyrene, α -Monovinyl aromatic compounds such as fluorostyrene; vinyl halides such as vinyl chloride and vinylidene chloride; vinyl esters such as vinyl propionate.

  Examples of the ethylenically unsaturated sulfonic acid monomer that can be used as the (c) ethylenically unsaturated monomer include isoprene sulfonic acid, styrene-3-sulfonic acid, styrene-4-sulfonic acid, and α-methylstyrene- 3-sulfonic acid, α-methylstyrene-4-sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, allylalkylsulfonic acids, sulfates of polyoxyethylene alkylallyl ether, polyoxyethylene polyoxypropylene alkylallyl And ether sulfates. These ethylenically unsaturated sulfonic acid monomers can be used alone or in admixture of two or more.

  In addition, the (c) ethylenically unsaturated monomer may be a salt of the above-mentioned ethylenically unsaturated sulfonic acid monomer, such as a sodium salt, potassium salt, or ammonium salt of the ethylenically unsaturated sulfonic acid monomer. Can be used. These salts of ethylenically unsaturated sulfonic acid monomers can be used alone or in admixture of two or more.

  (C) Examples of the ethylenically unsaturated monomer include caprolactone-modified acetoxy (meth) acrylate, and the following trade names: Plaxel ATFA1, Plaxel ATFA2, Plaxel ATFM1, Plaxel ATFM2 (above, manufactured by Daicel Chemical Industries, Ltd.) ), Etc .; γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ -Mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4-epoxycyclohexylethyltriethoxysilane, vinyltrimethoxysilane And vinyl triethoxysilane. Among the ethylenically unsaturated monomers listed here, methyl methacrylate, hydroxyalkyl methacrylate, methoxyethyl acrylate, ethoxymethyl acrylate, and γ-methacryloxy are used from the viewpoint of improving water resistance, adhesive strength, and holding power. Propyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane are preferably used in the present invention.

  The water-insoluble tackifier that can be used in the water-based pressure-sensitive adhesive composition of the present invention includes natural rosins such as gum rosin, tall oil rosin, and wood rosin, and purified products thereof, disproportionation, hydrogenation, dehydration, or Dimerized polymerized rosin, various modified rosins such as sulfonated products, or addition reaction products of maleic acid, maleic anhydride, fumaric acid, acrylic acid and the like to rosin and their esters, partial esters or partial amidated products, terpenes Phenol etc. can be mentioned. These water-insoluble tackifiers can be used alone or in combination of two or more. Among the water-insoluble tackifiers listed here, an aqueous dispersion of terpene phenol and polymerized rosin is preferably used in the present invention in terms of adhesive strength.

  The aqueous pressure-sensitive adhesive composition of the present invention may contain a crosslinking agent. In particular, the water-based pressure-sensitive adhesive composition of the present invention is 0.1 to 10 parts by mass of a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm in an emulsion polymerization reaction system for obtaining a copolymer dispersion. It is preferable that a crosslinking agent is included before coating. When a crosslinking agent is present before coating, anchoring properties and holding power can be improved.

  As a crosslinking agent that can be used in the water-based pressure-sensitive adhesive composition of the present invention, a commonly used crosslinking agent can be used. For example, a polyfunctional isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent. Agents, metal chelate-based crosslinking agents, and dihydrazide compounds such as adipic acid dihydrazide. This cross-linking agent may be either oil-soluble or water-soluble. A crosslinking agent can be used 1 type or in combination of 2 or more types. As the crosslinking agent, for example, when the polymer constituting the polymer particles of the water-based emulsion is the specific acrylic polymer as described above, among the epoxy-based crosslinking agents, particularly ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl. Ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, o-phthalic acid diglycidyl ester, glycerin polyglycidyl Ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyol Glycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, N, N, N ′, N′-pentaglycidyldiethylenetriamine, N, N, N ′, N′-tetraglycidylethylenediamine, etc. A polyglycidyl compound containing two or more epoxy groups can be used. Among the cross-linking agents listed here, polyglycerol polyglycidyl ether and polyethylene glycol diglycidyl ether are preferably used in the present invention from the viewpoint of enhancing miscibility and adhesive strength.

  The water-based pressure-sensitive adhesive composition of the present invention includes various additives used for general water-based pressure-sensitive adhesives, such as white pigments, thickeners, wetting agents, alkali agents, stabilizers and emulsifiers, and the above-described water-insoluble pressure-sensitive adhesives. You may contain the tackifier different from an imparting agent, antiseptic | preservative, antifungal agent, etc.

  When forming the adhesive layer of adhesive labels / sheets / tapes using the aqueous adhesive composition of the present invention, the base material of the adhesive labels / sheets / tapes is paper, cloth, polyvinyl chloride, polypropylene. Polyester, polyimide, foam, metal foil and the like can be used. Examples of adherents for adhesive labels, sheets, and tapes include plastic, metal, paper, glass, silicone, ceramic, and skin.

  The aqueous pressure-sensitive adhesive composition of the present invention can be obtained, for example, by the production method described below.

  The copolymer dispersion contained in the aqueous pressure-sensitive adhesive composition of the present invention comprises (a) an ethylenically unsaturated carboxylic acid monomer and (b) an alkyl ester monomer having 4 to 12 carbon atoms. c) It can be obtained by polymerizing a mixture of ethylenically unsaturated monomers (hereinafter referred to as “monomer mixture”) by an emulsion polymerization method.

  Specifically, a pre-emulsion is prepared by emulsifying a mixture of monomers and water using an emulsifier, and a water-insoluble tackifier, a polymerization initiator and a molecular weight modifier are added to the pre-emulsion, Subsequently, the polymerization reaction is usually carried out under an inert atmosphere. As a result, a copolymer dispersion containing particles of an acrylic copolymer, particles of a water-insoluble tackifier, and particles composed of an acrylic copolymer and a water-insoluble tackifier can be obtained.

  Alternatively, a dispersion in which a water-insoluble tackifier is dispersed in a medium (for example, water) is prepared in advance, and a polymerization reaction may be performed by an emulsion polymerization method while adding a mixture of monomers or an emulsifier to the dispersion ( See examples for details).

  The above-described two types of emulsion polymerization methods can be carried out satisfactorily even when not passing through the step of pulverizing the tackifier and dissolving it in the monomer, or the step of dispersing the emulsified droplets with a high-pressure homogenizer. That is, in the present invention, emulsion polymerization can be easily performed.

  In the polymerization reaction, the polymerization reaction of the mixture of monomers can be performed while supplying the pre-emulsion and the polymerization initiator continuously or intermittently to the reaction system.

  As the polymerization initiator, persulfate alone or a redox polymerization initiator can be used. A redox polymerization initiator is a polymerization initiator in which an oxidizing agent and a reducing agent are combined. Here, the oxidizing agent used for the redox polymerization initiator may be one kind or a mixture of plural kinds. Further, the reducing agent used for the redox polymerization initiator may be one kind or a mixture of plural kinds.

  Examples of the oxidizing agent used for the redox polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxymaleic acid, and succinic acid. Acid peroxide, benzoyl peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate, cumyl peroxyneodecanoate, cumyl peroxy octoate, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide, 2,2- A peroxide such as bis (4,4-di-t-butylperoxycyclohexyl) propane can be used.

  On the other hand, as the reducing agent used for the redox polymerization initiator, for example, acidic sodium sulfite, sodium dithionite, sodium thiosulfate, Rongalite, ascorbic acid, fructose and other reducing sugars, ferrous sulfate, ferric sulfate And iron salts. Moreover, when using for a redox-type polymerization initiator, you may use together chelating agents, such as ethylenediaminetetraacetic acid sodium, as needed.

When obtaining a copolymer dispersion contained in the aqueous pressure-sensitive adhesive composition of the present invention, when a redox polymerization initiator is used in the polymerization reaction, a preferable combination of the oxidizing agent, reducing agent, and chelating agent listed above is preferable. For example, the following three sets (A to C) can be mentioned.
(Combination A) Persulfate, acidic sodium sulfite, ferrous sulfate (combination B) t-butyl hydroperoxide, acidic sodium sulfite, ferrous sulfate (combination C) p-menthane hydroperoxide, ferrous sulfate , Sodium ethylenediaminetetraacetate, sodium formaldehyde sulfoxylate

  The ratio of the redox polymerization initiator used is as follows: (a) an ethylenically unsaturated carboxylic acid monomer, (b) an alkyl ester monomer having 4 to 12 carbon atoms and (c) an ethylenically unsaturated monomer. It is preferably 0.01 to 5.0 parts by mass, more preferably 0.05 to 3.0 parts by mass, and still more preferably 0.1 to 1.0 parts by mass with respect to 100 parts by mass of the total mass. Part. In addition, when the oxidizing agent used for the redox polymerization initiator is a persulfate alone, (a) an ethylenically unsaturated carboxylic acid monomer and (b) a single acrylate ester having 4 to 12 carbon atoms in the alkyl group It is preferable that the usage-amount of a redox-type polymerization initiator is 0.1-1.0 mass part with respect to 100 mass parts of total amounts of a body and (c) ethylenically unsaturated monomer.

  In obtaining the copolymer dispersion contained in the aqueous pressure-sensitive adhesive composition of the present invention, polyoxyethylene alkyl ether, polyoxyethylene alkyl sulfate ester salt, polyoxyethylene polycyclic phenyl ether sulfate can be used as an emulsifier that can be used in the polymerization reaction. Listed are surfactants such as ester salts, sodium polyoxyethylene alkyl succinate, sodium lauryl sulfate, sodium dodecylbenzene sulfonate. For example, “Latemul S-180A” and “PD-104” manufactured by Kao Corporation; “Eleminol JS-2” manufactured by Sanyo Chemical Co., Ltd .; “Aqualon KH-10” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. “Adekaria Soap SE-10N” and “SR-10N” manufactured by Asahi Denka Kogyo Co., Ltd .; “AntoxMS-60” manufactured by Nippon Emulsifier Co., Ltd. “Surfmer FP-120 manufactured by Toho Chemical Industry Co., Ltd.” Any reactive emulsifier such as “can be used.

  The proportion of emulsifier used is the total amount of (a) an ethylenically unsaturated carboxylic acid monomer, (b) an alkyl ester monomer having 4 to 12 carbon atoms and (c) an ethylenically unsaturated monomer. It is preferable that it is 0.2-7.0 mass parts with respect to 100 mass parts, More preferably, it is 0.5-5.0 mass parts, More preferably, it is 0.7-3.0 mass parts.

  In obtaining the copolymer dispersion contained in the aqueous pressure-sensitive adhesive composition of the present invention, the molecular weight regulator that can be used in the polymerization reaction includes butyl mercaptan, dodecyl mercaptan, octyl thioglycolate, isopropyl alcohol, methanol, carbon tetrachloride, etc. Can be mentioned.

  The proportion of the molecular weight regulator used is as follows: (a) an ethylenically unsaturated carboxylic acid monomer; (b) an alkyl ester monomer having 4 to 12 carbon atoms in the alkyl group; and (c) an ethylenically unsaturated monomer. The total amount is preferably 0.001 to 0.50 parts by mass, more preferably 0.003 to 0.30 parts by mass, and still more preferably 0.005 to 0.20 parts by mass. is there.

  Copolymer in which particles of acrylic copolymer having a weight-average molecular weight (Mw) and tetrahydrofuran-insoluble (THF-insoluble) having a desired size are dispersed by appropriately selecting the type and use ratio of the molecular weight regulator. A dispersion can be obtained.

  According to the water-based pressure-sensitive adhesive composition of the present invention, sufficient adhesive strength and water resistance can be obtained, and high cohesive force can be obtained by the interaction between the carboxyl groups in the acrylic copolymer particles. As a result, a good holding force can be obtained. Furthermore, according to the water-based pressure-sensitive adhesive composition of the present invention, since the tetrahydrofuran-insoluble content (THF-insoluble content) is 70% or less, high penetrability to the base material can be obtained when an adhesive layer is formed. As a result, good throwing performance can be obtained. Moreover, according to the manufacturing method of the aqueous adhesive composition mentioned above, the aqueous adhesive composition which is excellent in said water resistance and adhesive force can be manufactured with high productivity.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

(1) Raw materials In the examples and comparative examples, the following raw materials were used.

(1-1) Monomer:
Component (a) (ethylenically unsaturated carboxylic acid monomer):
Acrylic acid (Manufacturer: Toagosei)
Methacrylic acid (Manufacturer: Kuraray)

(B) component (acrylic acid ester monomer):
2-ethylhexyl acrylate (manufacturer: Toagosei Co., Ltd.)
Butyl acrylate (Manufacturer: Toagosei)

Component (c) (ethylenically unsaturated monomer):
Methyl methacrylate (Manufacturer: Mitsubishi Rayon Co., Ltd.)
Styrene (Manufacturer: Mitsubishi Chemical Corporation)
Methoxyethyl acrylate (Manufacturer: Osaka Organic Chemical Company)
γ-Methacryloxypropyltrimethoxysilane (Manufacturer: Shin-Etsu Silicone)
2-Hydroxyethyl methacrylate (Manufacturer: Osaka Organic Chemical Industry Co., Ltd.)

(1-2) Water-insoluble tackifier:
Terpenephenol E200-NT (average particle size 0.66 μm, manufacturer: Arakawa Chemical Industries)
Polymerized rosin E865-NT (average particle size 0.66 μm, manufacturer: Arakawa Chemical Industries)

(1-3) Rosin emulsifier for water-soluble emulsion polymerization:
EO-added rosin ester DRA-1500 (particle size cannot be measured with aqueous solution, manufacturer: Toho Chemical Industry Co., Ltd.)

(1-4) Emulsifier:
Non-reactive emulsifier: New Coal 707SF (Manufacturer: Nippon Emulsifier Co., Ltd.)
Reactive emulsifier: KH-1025 (manufacturer: Daiichi Kogyo Seiyaku Co., Ltd.)

(1-5) Other:
Thickener: UH-420 (Manufacturer: Adeka)
Wetting agent: Surflon S234 (Manufacturer: Sey Chemical Co.)

(2) Copolymerization reaction (Examples 1 to 3, Comparative Examples 1 to 4)
In Examples 1 to 3 and Comparative Examples 1 to 4, the monomers (a) to (c) and the water-insoluble tackifier were mixed and reacted at the ratios shown in Table 1 [Note] The numerical values shown in Table 1 represent parts by mass, and the sum of the monomers of components (a) to (c) is 100 parts by mass. In addition, the numerical value of “parts by mass” described below is 100 parts by mass unless otherwise specified. ]. Specifically, first, a water-insoluble tackifier and water previously dispersed in water were charged into a reaction vessel, and stirred under a nitrogen stream to prepare dispersion A. The temperature of the dispersion A is raised to 70 ° C., and then 1 part by mass of the mixed solution of the monomers (a) to (c), 40 parts by mass of water, and Newcol 707SF is added to the dispersion A. And pre-emulsified by stirring, and a pre-adjusted catalyst aqueous solution (0.1% ammonium persulfate aqueous solution) was dropped into the reaction vessel at 80 ° C. in parallel with the pre-emulsified monomer over about 3 hours, and the dropping was completed. After that, it was kept at 80 ° C. for about 1 hour. After cooling, 1.4 parts by mass of 25% aqueous ammonia was added, and then UH-420 was gradually added to adjust the viscosity to about 25000 mPa · s, and 0.35 parts by mass of Surflon S234 was added to obtain an adhesive composition. Obtained.

Example 4
In Example 4, the monomers (a) to (c) and the water-insoluble tackifier were used in the proportions shown in Table 1, and the amount of New Coal 707SF was 0.5 parts by mass. The emulsion polymerization was carried out in the same manner as in Example 1 except that the amount of KH-1025 was 0.5 parts by mass.

(Comparative Examples 5 and 6)
In Comparative Examples 5 and 6, the monomers of the components (a) to (c) were blended in the proportions shown in Table 1, and further, in the blending shown in Table 1 instead of the water-insoluble tackifier. Emulsion polymerization was carried out in the same manner as in Example 1 except that the dispersion A was prepared by dissolving a rosin emulsifier for water-soluble emulsion polymerization (EO-added rosin ester DRA-1500) in water.

(Comparative Example 7)
In Comparative Example 7, each raw material was used in the ratio shown in Table 1. Further, instead of using the dispersion A charged with a water-insoluble tackifier and water, the water-insoluble tackifier is dried at 100 ° C. and then pulverized in a mortar, and then water-insoluble tackifier is provided. Emulsion polymerization was carried out in the same manner as in Example 1 except that the powder of the agent was directly dissolved in the mixed solution of the monomers (a) to (c).

(Comparative Example 8)
In Comparative Example 8, each raw material was used in the ratio shown in Table 1. Moreover, after emulsion polymerization was performed without adding the water-insoluble tackifier powder, the same procedure as in Comparative Example 7 was performed, except that the water-insoluble tackifier powder was added before coating.

  In Examples 1 to 4 and Comparative Examples 1 to 4, 6, and 8, water-based adhesives could be obtained. In Comparative Examples 5 and 7, a large amount of aggregates were produced during emulsion polymerization, and an aqueous adhesive could not be obtained.

  The aqueous adhesives obtained in Examples 1 to 4 and Comparative Examples 1 to 4, 6, and 8 were evaluated in the following (3) to (10).

(3) Measurement of glass transition point The glass transition point was measured by the method based on JISK7121. The results are shown in Table 1.

(4) Measurement of average particle diameter The average particle diameter was measured by Microtrac MT3000 (Nikkiso Co., Ltd.). The results are shown in Table 1.

(5) Measurement of tetrahydrofuran insoluble content (THF insoluble content) The method for measuring the insoluble content when dissolved in tetrahydrofuran was to add 0.15 g of the dry film of the pressure-sensitive adhesive composition to 50 mL of tetrahydrofuran, and stir and dissolve for 16 hours. The solution was filtered using filter paper corresponding to two types of JIS P3801, 10 mL of the filtrate was collected, dried, and then the insoluble content (gel fraction) was calculated from the dried mass. The results are shown in Table 1 [column of “THF insoluble matter (mass%)” in Table 1].

(6) Preparation of test piece Using an applicator, a test piece was prepared by applying a water-based adhesive (coating amount DRY 20 to 25 µm) to a release paper (Separator EN78P manufactured by Lintec Corporation) under the following conditions.
Drying conditions: 115 ° C. × 90 seconds with hot air dryer Base material: 50 μm PET film Curing: 40 ° C. × 3 days

(7) Measurement of adhesive strength The adhesive strength was measured by a method according to JIS Z 0237. The measurement conditions are as follows. The results are shown in Table 1.
Peel: 180 ° peel (peel speed 300mm / min)
Substrate: SUS305 or polypropylene test piece width: 25 mm
Crimping: 2 kg roller x 1 reciprocation on each adherend under 23 ° C x 50% RH conditions Timing of crimping tension test: Tensile test conducted 1 day after application

(8) Measurement of holding force A load of 500 g was applied in an atmosphere of 40 ° C. and 65%, and the deviation width was measured after 24 hours. The case where the deviation width was 1 mm or less was evaluated as “excellent”, the case where it exceeded 1 mm and 3 mm or less was “good”, the case where it exceeded 3 mm, or the case where it was dropped was evaluated as “not possible”. The results are shown in Table 1.

(9) Evaluation of water whitening resistance The test piece was immersed in ion-exchanged water (23 ° C.), and the whitening of the adhesive was visually observed after 3 hours. `` Excellent '' if whitening is not observed or slightly bluish but transparent, `` good '' if slightly whitened but transparent, `` good '' if whitened or not transparent It was evaluated as “impossible”. The results are shown in Table 1.

(10) Evaluation of anchoring property The number of times until the adhesive peels off from the substrate when the test piece is folded and the adhesive surfaces are bonded together (self-adhesion) and the peeling operation is repeated is measured. did. The case of 10 times or more was evaluated as “excellent”, the case of 5-9 times as “good”, and the case of 4 times or less as “impossible”. The results are shown in Table 1.

  The water-based pressure-sensitive adhesives of Examples 1 to 4 had sufficient adhesive strength and anchoring properties, and had excellent water resistance.

  On the other hand, the water-based adhesives according to Comparative Examples 1 to 8 were unsuitable as described below.

  Although the comparative example 1 is an example outside the range prescribed | regulated by this invention in the point which does not use a water-insoluble tackifier, it was confirmed that it lacks adhesive force and holding power.

  Comparative Example 2 is an example in which the amount of the water-insoluble tackifier exceeds the range defined in the present invention, but it was confirmed that the water resistance is insufficient.

  Comparative Example 3 is an example in which the component (a) exceeds the range defined in the present invention, but is poor in water resistance and adhesion to polyolefin.

  Comparative Example 4 is an example in which the THF-insoluble content exceeds the range defined in the present invention, but the anchoring property and adhesive strength to polyolefin are inferior.

  From Comparative Examples 5 and 6, in place of the water-insoluble tackifier defined in the present invention, when a water-soluble rosin emulsifier for emulsion polymerization (EO-added rosin ester DRA-1500) is used, for emulsion polymerization It was found that an adhesive could not be obtained unless a large amount of rosin emulsifier was used. Further, as shown in Comparative Example 6, even when a pressure-sensitive adhesive can be obtained by using a large amount of a rosin emulsifier for water-soluble emulsion polymerization (EO-added rosin ester DRA-1500), it is retained. It was found that the strength and water resistance were inferior.

  In Comparative Example 7, seed polymerization is not performed. Without seed polymerization, an aqueous adhesive could not be obtained.

  In Comparative Example 8, the blending ratio of the raw materials is the same as that in Example 3. Comparing Comparative Example 8 and Example 3, after performing emulsion polymerization in a state where the reaction system does not contain a water-insoluble adhesive, a water-insoluble tackifier was added (added later) before coating. It was also found that the adhesive strength, holding power and water whitening resistance were inferior. That is, it was found that the adhesive strength, holding power, and water whitening resistance can be improved by performing seed polymerization in the presence of a water-insoluble adhesive as in Example 3.

  The present invention can be used as an aqueous adhesive composition and a method for producing the same.

Claims (5)

(A) 0.1 to 10 parts by mass of an ethylenically unsaturated carboxylic acid monomer, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group, and (c) an ethylenically unsaturated monomer. 0 to 39.9 parts by weight of a saturated monomer [where (a) + (b) + (c) = 100 parts by weight] and a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm Containing a copolymer dispersion obtained by emulsion polymerization in a reaction system containing 0.1 to 10 parts by mass,
The average particle size of the particles contained in the copolymer dispersion is 0.3 to 10 μm,
The copolymer dispersion is an aqueous pressure-sensitive adhesive composition having a glass transition point of −70 to −30 ° C. and an insoluble content of 70% by mass or less when dissolved in tetrahydrofuran.   The water-based pressure-sensitive adhesive composition according to claim 1 containing a crosslinking agent.   In a dispersion in which 0.1 to 10 parts by mass of a water-insoluble tackifier having an average particle size of 0.05 to 1.00 μm was dispersed in a medium, (a) an ethylenically unsaturated carboxylic acid monomer 0.1 to 10 parts by mass, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group, and (c) 0 to 39.9 parts by mass of an ethylenically unsaturated monomer [provided that (a ) + (B) + (c) = 100 parts by mass], and a method for producing an aqueous pressure-sensitive adhesive composition by obtaining a copolymer dispersion by emulsion polymerization.   (A) 0.1 to 10 parts by mass of an ethylenically unsaturated carboxylic acid monomer, (b) 60 to 99 parts by mass of an acrylate monomer having 4 to 12 carbon atoms in the alkyl group, and (c) an ethylenically unsaturated monomer. To a pre-emulsion containing 0 to 39.9 parts by mass of a saturated monomer [where (a) + (b) + (c) = 100 parts by mass], a medium and an emulsifier, an average particle size of 0.05 to 1. A method for producing an aqueous pressure-sensitive adhesive composition, wherein a copolymer dispersion is obtained by adding 0.1 to 10 parts by mass of a water-insoluble tackifier having a size of 00 μm and emulsion polymerization.   The method for producing an aqueous pressure-sensitive adhesive composition according to claim 3 or 4, wherein a crosslinking agent is added to the copolymer dispersion.