JP2007217594A - Acrylic water-based adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an acrylic water-based adhesive that controls branching by side reactions in emulsion polymerization, keeps flexibility of coating film even after adding a crosslinking agent, has excellent adhesive strength and holding power and excellent adhesive strength even to an uneven rough surface such as urethane foam. <P>SOLUTION: The acrylic water-based adhesive is obtained by subjecting a polymerizable monomer component comprising 0.1-10 wt.% of a carboxy group-containing ethylenic unsaturated monomer (A) and 45-99.9 wt.% of a 1-12C alkyl group-containing alkyl (meth)acrylate (B) to emulsion polymerization in the presence of a polymerization initiator (X) in an aqueous medium to give an acrylic polymer (P) and further crosslinking the acrylic polymer with an oil-soluble epoxy compound (C) and has a radical generated amount (Rd) calculated based on the used amount of the polymerization initiator (X) of 2×10<SP>-13</SP>-150×10<SP>-13</SP>mol/l/min, the gel fraction of the coating film (P) before crosslinking of ≤20 wt.% and the gel fraction of the coating film after crosslinking with the oil-soluble epoxy compound (C) of 10-50 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an acrylic aqueous adhesive. More specifically, the acrylic water base has better adhesion and holding power than conventional pressure-sensitive adhesives, and has excellent adhesion and holding power, particularly on rough surfaces such as urethane foam. It relates to an adhesive.

  In recent years, the shift from solvent-based resins to products using aqueous resins has been rapidly progressing in a wide range of fields for the purpose of reducing environmental burdens, and the water-based adhesives are also eagerly desired to be water-based at an early stage.

  For example, the development of an acrylic emulsion-type pressure-sensitive adhesive obtained by emulsion polymerization of various ethylenically unsaturated monomers in an aqueous medium has been studied as an aqueous pressure-sensitive adhesive. In the case of an acrylic emulsion type adhesive, not only when using a solvent type resin or an aqueous resin, but a cross-linking agent is added in order to provide holding power (that is, resistance to the shear direction applied to the formed adhesive layer). In such a method, the holding power is somewhat improved, but the adhesive strength tends to decrease, and it is difficult to express both the adhesive strength and the holding strength in a balanced manner. It was difficult. In particular, there is a problem that the adhesive strength (hereinafter referred to as “rough surface adhesion”) tends to be reduced on rough surfaces having irregularities such as urethane foam.

  Acrylic emulsion adhesives generally have poorer surface adhesion when using aqueous resins than solvent-based resins. One of the causes is the effect of differences in polymer structure between solvent-based resins and aqueous resins. Is mentioned.

  That is, an acrylic polymer obtained by emulsion polymerization tends to cause a side reaction such as a hydrogen abstraction reaction due to radicals present in excess in the reaction system, and the polymer chain branches to take a crosslinked structure. By forming this crosslinked structure, the flexibility of the resulting pressure-sensitive adhesive film is lowered, and the flexibility of the film is further impaired by adding a crosslinking agent. For this reason, the suppression of side reactions as described above has been a major problem in shifting to a pressure-sensitive adhesive using an aqueous resin.

  In order to deal with such a problem, a monomer containing (meth) acrylic acid alkyl ester is emulsion-polymerized by batch charging using a polymerization initiator having a 10-hour half-life temperature of 70 ° C. or less to form a first aqueous dispersion. Separately, a polymerization initiator is added to water, and emulsion polymerization is performed while dropping a water emulsion of a monomer containing (meth) acrylic acid alkyl ester thereto to obtain a second aqueous dispersion. A method for producing a water-dispersed acrylic pressure-sensitive adhesive in which the first and second aqueous dispersions are mixed has been proposed, and an adhesive obtained by such a production method has an adhesiveness and cohesive strength of 2 It is said that two characteristics can be compatible (for example, refer to Patent Document 1). However, the pressure-sensitive adhesive obtained by the production method described in Patent Document 1 is still unsatisfactory because its adhesive force and holding force are still insufficient with respect to rough surfaces such as urethane foam.

JP 2002-60713 A

  The object of the present invention is to suppress the branching of the polymer chain resulting from a side reaction during emulsion polymerization, to obtain a substantially linear acrylic polymer with little branched structure, and even after addition of a crosslinking agent Acrylic water-based pressure-sensitive adhesive that can maintain the flexibility of the coating, has excellent balance between adhesion and retention, and has excellent adhesion (rough surface adhesion) even on rough surfaces such as urethane foam. Is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a polymerizable monomer component that essentially contains a carboxyl group-containing ethylenically unsaturated monomer and a specific alkyl (meth) acrylate. Is an acrylic aqueous pressure-sensitive adhesive obtained by crosslinking an acrylic polymer obtained by emulsion polymerization in an aqueous medium in the presence of a polymerization initiator, and (1) calculated based on the amount of the polymerization initiator used. By controlling the radical generation amount (Rd) within a specific range, the branching reaction, which is a side reaction during emulsion polymerization, can be suppressed, and the resulting acrylic polymer has a linear structure with few branched structures. (2) By crosslinking the acrylic polymer having a linear structure with few branched structures with an oil-soluble epoxy compound, the flexibility of the pressure-sensitive adhesive film can be maintained, and adhesive strength, particularly urethane foam, can be maintained. Such as excellent adhesion even to a rough surface having irregularities that while retaining force maintaining the (rough surface adhesiveness) is improved, and have completed the present invention have found the like.

That is, the present invention relates to an alkyl (meth) acrylate (B) 45 to 99.99 having 0.1 to 10% by weight of a carboxyl group-containing ethylenically unsaturated monomer (A) and an alkyl group having 1 to 12 carbon atoms. An acrylic polymer (P) obtained by emulsion polymerization of a polymerizable monomer component containing 9% by weight in an aqueous medium in the presence of a polymerization initiator (X), and an oil-soluble epoxy compound An aqueous acrylic pressure-sensitive adhesive crosslinked by (C), wherein the radical generation amount (Rd) calculated based on the amount of the polymerization initiator (X) used is a polymerizable monomer component in the reaction system It is in the range of 2 × 10 ^{−13 to} 150 × 10 ⁻¹³ mol per liter per minute, and the gel fraction of the film formed from the acrylic polymer (P) before crosslinking is 20% by weight or less. And a rack made of the oil-soluble epoxy compound (C). The present invention provides an acrylic aqueous pressure-sensitive adhesive characterized in that the gel fraction of the coating film after the bridge is 10 to 50% by weight.

  The acrylic water-based pressure-sensitive adhesive of the present invention is capable of suppressing branching resulting from side reaction during emulsion polymerization by controlling the radical generation amount calculated based on the amount of polymerization initiator used within a specific range, and has a branched structure. An acrylic polymer with a low linear structure can be obtained, and the acrylic polymer can be crosslinked with an oil-soluble epoxy compound as a crosslinking agent to maintain the flexibility of the film formed with the adhesive even after crosslinking. It is possible to achieve both excellent adhesive strength and holding power characteristics, and in particular, it can exhibit excellent adhesive strength (rough surface adhesion) even on rough surfaces with unevenness such as urethane foam.

  First, in the acrylic water-based pressure-sensitive adhesive of the present invention, a carboxyl group-containing ethylenically unsaturated monomer (A) [hereinafter also referred to as an unsaturated monomer (A), which is a first essential component. ] Is not particularly limited as long as it is a compound having a carboxyl group and an ethylenically unsaturated group in the molecule. For example, (meth) acrylic acid, β-carboxyethyl (meth) acrylate, 2- (meth) acryloylpropionic acid , Crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid half ester, maleic acid half ester, maleic anhydride, itaconic anhydride, ω-carboxy-polycaprolactone (meth) acrylate, β- (meth) acryloyloxyethyl Examples thereof include hydrogen succinate, β- (meth) hydroxyethyl hydrogen phthalate, and salts thereof. These may be used alone or in combination of two or more. Among these, (meth) acrylic acid is preferable because it is excellent in stability during polymerization of the monomer, adhesive properties, water whitening resistance, and the like.

  The amount of the unsaturated monomer (A) used is in the range of 0.1 to 10% by weight, preferably in the range of 1 to 10% by weight, based on the total amount of the polymerizable monomer components. More preferably, it is in the range of 2.5 to 10% by weight. As long as the amount of the unsaturated monomer (A) used is within such a range, excellent adhesion and holding power can be expressed, and the crosslinking reaction with the oil-soluble epoxy compound (C), which will be described later, efficiently proceeds. To do.

  Next, alkyl (meth) acrylate (B) having an alkyl group having 1 to 12 carbon atoms, which is the second essential component [hereinafter also referred to as alkyl (meth) acrylate (B). ] Will be described below.

  Examples of the alkyl (meth) acrylate (B) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, and n-hexyl. (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, n -Lauryl (meth) acrylate etc. are mentioned, These may be used individually and may use 2 or more types together. Among these, an alkyl (meth) acrylate having an alkyl group having 4 to 9 carbon atoms is preferable because of good polymerizability.

  The amount of the alkyl (meth) acrylate (B) used is preferably in the range of 45 to 99.9% by weight, more preferably 80 to 99.9% by weight based on the total amount of the polymerizable monomer components. % Range. If the amount of the alkyl (meth) acrylate (B) used is within such a range, it is easy to adjust the glass transition temperature (Tg) of the coating formed with the target acrylic aqueous pressure-sensitive adhesive and to maintain the flexibility of the coating. Acrylic that can balance both excellent adhesion and holding properties in a well-balanced manner, and has excellent adhesion (rough surface adhesion), especially for rough surfaces such as urethane foam. An aqueous pressure-sensitive adhesive can be obtained.

  Among the alkyl (meth) acrylates (B), for example, alkyl (meth) acrylates having an alkyl group having 1 to 3 carbon atoms such as methyl (meth) acrylate and ethyl (meth) acrylate, When used together in the range of 1 to 15% by weight of the polymerizable monomer component, the cohesive strength of the coating film formed from the acrylic aqueous pressure-sensitive adhesive of the present invention can be further improved.

  Next, the radical generation amount (Rd) calculated based on the used amount of the polymerization initiator (X) and the polymerization initiator (X), which are essential in the present invention, will be described below.

In the acrylic aqueous pressure-sensitive adhesive of the present invention, the polymerizable monomer component is emulsion-polymerized in an aqueous medium in the presence of the polymerization initiator (X) to obtain an acrylic polymer (P). The radical generation amount (Rd) calculated based on the amount of polymerization initiator (X) used is 2 × 10 ^{−13 to} 150 × 10 ⁻¹³ mol per minute per liter of the polymerizable monomer component in the reaction system. By controlling in this range, branching caused by side reactions can be suppressed, and the resulting polymer chain has a linear structure. In the present invention, the “radical generation amount (Rd) calculated based on the amount of polymerization initiator (X) used” refers to the polymerizability present in the reaction system determined by the calculation formula described in the examples below. This is the amount of radicals generated per minute per liter of monomer component, and is described as 2 × 10 ^{−13 to} 150 × 10 ⁻¹³ mol / l / min. Further, the radical generation amount (Rd) is preferably ^{5 × 10 -13 ~120 × 10 -13} mol / l / min, more preferably ^{10 × 10 -13 ~100 × 10 -13} mol / l / min is there. If the radical generation amount is within such a range, good polymerization stability can be obtained, and the branching reaction of the acrylic polymer (P) can be further suppressed, resulting in a softer water-based pressure-sensitive adhesive film, such as adhesion to urethane foam. The property is further improved.

When the radical generation amount (Rd) is less than 2 × 10 ⁻¹³ mol / l / min, the amount of radicals generated at the time of emulsion polymerization is so small that the reaction does not proceed sufficiently and the desired performance may not be obtained. There is. In addition, when the radical generation amount (Rd) exceeds 150 × 10 ⁻¹³ mol / l / min, branching due to side reactions is likely to occur due to excessive radicals in the reaction system, and therefore the resulting polymer chain has a crosslinked structure. In addition, since the flexibility of the coating is impaired, when an oil-soluble epoxy compound (C) as a cross-linking agent, which is an essential component described later, is added and used as a pressure-sensitive adhesive, the adhesive strength, particularly the adhesive strength to urethane foam is reduced. There is a fear.

  In addition, as the polymerization initiator (X) used in the present invention, a radical polymerization initiator is used, and the kind thereof is not particularly limited. For example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate; Organic peroxides such as benzoyl oxide, cumene hydroperoxide, t-butyl hydroperoxide; hydrogen peroxide; 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidino) (Propane) Various polymerization initiators such as azo initiators such as dihydrochloride. Among these, persulfates and azo initiators are preferable because they hardly cause side reactions such as hydrogen abstraction reaction. The said polymerization initiator may be used individually and may use 2 or more types together.

  The reaction temperature at the time of emulsion polymerization in an aqueous medium is not particularly limited as long as the radical generation amount (Rd) during the reaction can be controlled within the appropriate range described above, but is preferably in the range of 30 to 90 ° C. Within such a temperature range, the radical generation amount (Rd) during the reaction can be controlled within the proper range of the present invention, so that the reaction operation becomes easy and good polymerization stability can be obtained.

  Moreover, since it is easy to control the radical generation amount (Rd) during emulsion polymerization within the above-mentioned range, it is preferable to complete the reaction at or below the 10-hour half-life temperature of the polymerization initiator used for the reaction.

  When the radical generation amount (Rd) during emulsion polymerization is controlled within the above-mentioned range, branching due to side reactions can be suppressed. Therefore, the acrylic polymer (P) before the addition of the oil-soluble epoxy compound (C) as a crosslinking agent is added. ), That is, the gel fraction of the film formed from the acrylic polymer (P) before crosslinking can be reduced to 20% by weight or less. The lower the gel fraction of the film formed from the acrylic polymer (P) before cross-linking, the more preferable, specifically, the gel content of the film formed from the polymer before cross-linking of the acrylic polymer (P). When the ratio is 10% by weight or less, it is more preferable because the flexibility of the film can be maintained even after the addition of the oil-soluble epoxy compound (C) and crosslinking, and further the polymer before crosslinking of the acrylic polymer (P). It is particularly preferable to control the gel fraction of the coating formed from 5% by weight or less. When the gel fraction before crosslinking of the coating exceeds 20% by weight, the degree of branching of the polymer chain becomes too high, the linear structure of the polymer chain is inhibited, and the flexibility of the coating is lowered.

  The “gel fraction” as used in the present invention means the ratio of the insoluble content of the coating formed from the acrylic polymer (P) to toluene, and is determined by the measurement method and formula described in the examples below. This is based on the required values. Further, the gel fraction is used in the same meaning not only before crosslinking but also after crosslinking.

  Furthermore, in the present invention, in order to use the acrylic polymer (P) as an acrylic water-based pressure-sensitive adhesive, the gel fraction after crosslinking is set to 10 to 10 by adding an oil-soluble epoxy compound (C) as a crosslinking agent. It is adjusted to a range of 50% by weight, preferably 15 to 45% by weight. As long as the gel fraction after crosslinking with the oil-soluble epoxy compound (C) is within the range, the flexibility of the film after crosslinking can be maintained, and both the properties of adhesion and holding power can be well balanced, especially urethane. An acrylic water-based pressure-sensitive adhesive having excellent adhesive force (that is, rough surface adhesiveness) can be obtained even on rough surfaces having irregularities such as foam, and the viscosity of the emulsion over time can be increased. And excellent storage stability.

  The oil-soluble epoxy compound (C) as a crosslinking agent is preferably added after emulsion polymerization since the flexibility of the pressure-sensitive adhesive film can be easily maintained.

  Examples of the oil-soluble epoxy compound (C) include Denacol EX-622 (manufactured by Nagase Kasei Kogyo Co., Ltd.), Denacol EX-201 (manufactured by the company), Denacol EX-212 (manufactured by the company), and Denacol EX-922 (manufactured by the company). , Denacol EX-2000 (manufactured by the company), Denacol EX-4000 (manufactured by the company), Denacol EX-721 (manufactured by the company), Denacol EX-221 (manufactured by the company), TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) , TETRAD-X (manufactured by the same company) and the like, and these may be used alone or in combination of two or more. Among these, TETRAD-C and TETRAD-X are preferable because a reaction with a carboxyl group is promoted by a nitrogen atom in the epoxy compound and a crosslinking reaction easily proceeds.

  In the present invention, when a cross-linking agent other than the oil-soluble epoxy compound (C) is used, the cross-linking density of the film formed with such a pressure-sensitive adhesive becomes too high, and in particular, the adhesiveness to a rough surface such as urethane foam is inferior. Since there exists a possibility, it is preferable to use the crosslinking agent other than the said oil-soluble epoxy compound to the minimum amount.

  Further, when a water-soluble epoxy compound is used as a crosslinking agent, the emulsion thickens with time and tends to be inferior in storage stability. This phenomenon is presumed to be caused by a cross-linking reaction between a water-soluble epoxy compound present in water and a water-soluble component such as an acid oligomer, which adversely affects the storage stability of the emulsion.

  In addition, the acrylic water-based pressure-sensitive adhesive of the present invention can be obtained by subjecting a crosslinkable compound to emulsion polymerization or a water-soluble or water-dispersible cross-linking agent before emulsion polymerization within a range not inhibiting the desired effect of the present invention. It may be used in any step such as during or after emulsion polymerization. Examples of the cross-linking agent used in this case include cross-linking of polyfunctional epoxy compounds, polyfunctional melamine compounds, polyfunctional polyamine compounds, polyfunctional polyethylenimine compounds, polyfunctional (block) isocyanate compounds, metal salt compounds, and the like. In addition to being able to be used alone or in combination of two or more, water-soluble or water-dispersible thermosetting resins such as phenol resins, urea resins, melamines Resin, urethane resin, etc. can be mixed and used, and there is no particular limitation.

  Moreover, the glass transition temperature (Tg) of the film formed using the acrylic aqueous pressure-sensitive adhesive of the present invention is preferably −25 ° C. or lower, more preferably −25 to −60 ° C. If the Tg of the film formed using the acrylic water-based pressure-sensitive adhesive is within a range, excellent adhesive force and holding force can be obtained in a well-balanced manner.

  Tg of the film formed using the acrylic aqueous pressure-sensitive adhesive is a carboxyl group-containing ethylenically unsaturated monomer (A) and an alkyl (meth) acrylate (B) having an alkyl group having 1 to 12 carbon atoms. ) And other ethylenically unsaturated monomers other than the unsaturated monomer (A) and the alkyl (meth) acrylate (B) as necessary. May be combined and copolymerized at an arbitrary ratio and adjusted within the Tg region of the appropriate film. In addition, the glass transition temperature (Tg) as used in the field of this invention is based on the numerical value measured by the method described in the Example.

  Moreover, the weight average molecular weight (Mw) when the tetrahydrofuran (THF) dissolved content of the acrylic polymer (P) is measured by gel permeation chromatography (GPC) is preferably in the range of 100,000 to 1,500,000. Preferably it is the range of 200,000 to 1,200,000, More preferably, it is the range of 250,000 to 1,000,000. If the Mw content of the acrylic polymer (P) dissolved in THF is within such a range, excellent adhesive properties such as rough surface adhesion, holding power, adhesive strength, and peel resistance can be obtained. In addition, the measurement of GPC is the value which measured only the melt | dissolution content after melt | dissolving in THF so that a polymer concentration might be set to 0.4%, and removing the insoluble content by filtration.

  Examples of the other ethylenically unsaturated monomers include (meth) acrylic acid aliphatic esters such as stearyl (meth) acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate, or (meth) acrylic fragrance. Group esters; 2,2,2-trifluoroethyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, β- (perfluorooctyl) ethyl Fluorine-containing ethylenically unsaturated monomers such as (meth) acrylates; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl Vinyl ethers such as ether and hexyl vinyl ether; nitrile group-containing ethylenically unsaturated monomers such as (meth) acrylonitrile; styrene, α-methylstyrene, vinyltoluene, vinylanisole, α-halostyrene, vinylnaphthalene, divinylstyrene, etc. Vinyl compounds having an aromatic ring; isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, N-vinylpyrrolidone and the like. Among these, it is preferable to use (meth) acrylic acid aliphatic esters or (meth) acrylic acid aromatic esters in terms of excellent stability during polymerization of the polymerizable monomer component.

  In addition, when the purpose is to further improve the gel fraction of the acrylic aqueous pressure-sensitive adhesive of the present invention within a desired range, as the other ethylenically unsaturated monomer, other than a carbonyl group or a carboxyl group It is also possible to use an ethylenically unsaturated monomer containing a crosslinkable reactive group.

  Examples of the ethylenically unsaturated monomer containing a crosslinkable reactive group other than the carbonyl group or the carboxyl group include glycidyl group-containing polymerizable monomers such as glycidyl (meth) acrylate and allyl glycidyl ether; 2-hydroxy Hydroxyl-containing polymerizable monomers such as ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate; aminoethyl (meth) acrylate, N-monoalkyl Amino group-containing polymerizable monomers such as aminoalkyl (meth) acrylate and N, N-dialkylaminoalkyl (meth) acrylate; N-methylol (meth) acrylamide, N-isopropoxymethyl (meth) acrylamide, N-butoxy Methyl (meta Methylolamide groups such as acrylamide and N-isobutoxymethyl (meth) acrylamide or alkoxyl-containing polymerizable monomers thereof; vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ Silyl group-containing polymerizable monomers such as-(meth) acryloxypropyltriisopropoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride; Lydinylethyl (meth) Polymerizable monomer containing aziridinyl group such as acrylate; isocyanate group such as (meth) acryloyl isocyanate, phenol of (meth) acryloyl isocyanate ethyl or methyl ethyl ketoxime adduct and / or blocked isocyanate group Oxazoline group-containing polymerizable monomers such as 2-isopropenyl-2-oxazoline and 2-vinyl-2-oxazoline; (meth) acrylamide, N-monoalkyl (meth) acrylamide, N, N-dialkyl ( Amide group-containing polymerizable monomers such as (meth) acrylamide; Cyclopentenyl group-containing polymerizable monomers such as dicyclopentenyl (meth) acrylate; Allyl group-containing polymerizable monomers such as allyl (meth) acrylate; Acrolein , Diacetone (meth) acrylamide, etc. A carbonyl group-containing polymerizable monomer; acetoacetyl group-containing polymerizable monomers such as acetoacetoxyethyl (meth) acrylate.

  Furthermore, as the other ethylenically unsaturated monomer, a polyfunctional ethylenically unsaturated monomer containing two or more ethylenically unsaturated groups in the molecule can be used. For example, ethylene glycol Di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) Examples include acrylate, diallyl phthalate, divinylbenzene, and allyl (meth) acrylate.

  In addition, as the other ethylenically unsaturated monomer, for the purpose of further improving the stability during emulsion polymerization and the storage stability of the acrylic polymer, a sulfonic acid group and / or sulfate. Polymerizable monomers containing groups (and / or salts thereof), phosphate groups and / or phosphate ester groups (and / or salts thereof) can be used, for example, vinyl sulfonic acid, styrene sulfone Vinyl sulfonic acids such as acids or salts thereof; Allyl group-containing sulfonic acids such as allyl sulfonic acid and 2-methylallyl sulfonic acid or salts thereof; (meth) acrylic acid 2-sulfoethyl, (meth) acrylic acid 2-sulfopropyl, etc. (Meth) acrylate group-containing sulfonic acids or salts thereof; (meth) acrylamide group-containing (meth) acrylamide-t-butylsulfonic acid and the like Such as sulfonic acids or salts thereof. Moreover, as a commercial item of the ethylenically unsaturated monomer which has a phosphoric acid group, "Adekaria soap PP-70" [Asahi Denka Kogyo Co., Ltd.], "PPE-710" [The company make], etc. are mentioned. .

  Moreover, when manufacturing the acrylic water-based pressure-sensitive adhesive of the present invention, a molecular weight modifier may be used. For example, lauryl mercaptan, octyl mercaptan, dodecyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropion A compound having a chain transfer ability such as acid, mercaptans such as thioglycerin, or α-methylstyrene dimer may be added when the polymerizable monomer component is emulsion polymerized using a molecular weight regulator.

  In the method for producing the acrylic aqueous pressure-sensitive adhesive of the present invention, when the polymerizable monomer component is emulsion-polymerized in an aqueous medium, it can be polymerized by using an emulsifier or other dispersion stabilizer. As the emulsifier that can be used in the present invention, various types of anionic emulsifier, nonionic emulsifier, cationic emulsifier, amphoteric emulsifier and the like can be used. Examples of the anionic emulsifier include sulfates of higher alcohols and salts thereof, alkylbenzene sulfonates, polyoxyethylene alkylphenyl sulfonates, polyoxyethylene alkyl diphenyl ether sulfonates, alkyl diphenyl ether disulfonates, and succinic acid. Nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene diphenyl ether, polyoxyethylene-polyoxypropylene block copolymer, etc .; cationic Examples of the emulsifier include alkylammonium salts such as dodecyl ammonium chloride, and the like. Examples of the amphoteric emulsifier include betaine ester type emulsifiers. Is, these emulsifiers may be used alone, the reaction may be used in combination of two or more in a range that does not inhibit.

  Furthermore, an emulsifier having a polymerizable unsaturated group (that is, a polymerizable unsaturated group) generally called “reactive emulsifier” in the molecule can be used, for example, a sulfonic acid group and a salt thereof. “Latemul S-180” (manufactured by Kao Corporation), “Eleminol JS-2” (manufactured by Sanyo Kasei Kogyo Co., Ltd.), “Eleminol RS-30” (manufactured by the same company), etc .; Aqualon HS-10 (Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon HS-20 (Company), Aqualon KH-05 (Company), KH-10 (Company), Adekaria "SOPE SE-10" (manufactured by Asahi Denka Kogyo Co., Ltd.), "ADEKA rear soap SE-20" (manufactured by the company), "ADEKA rear soap SR-10N" (manufactured by the company), "ADEKA rear soap SR-20N" [the company Manufactured] etc .; phosphoric acid "New Frontier A-229E" (produced by Daiichi Kogyo Seiyaku Co., Ltd.) and the like; "Aqualon RN-10" (produced by Daiichi Kogyo Seiyaku Co., Ltd.) having a nonionic hydrophilic group, "Aqualon RN-20" [ "Aqualon RN-30" (manufactured by the company), "Aqualon RN-50" (manufactured by the company), "Aqualon ER-10" (manufactured by the company), "Aqualon ER-20" (manufactured by the company), "Aqualon" ER-30 "(manufactured by the company)," Aqualon ER-40 "(manufactured by the company), and the like. These may be used alone or in combination of two or more. The use of a reactive emulsifier is preferable because it improves the stability during polymerization and further improves the water resistance of the film formed by the acrylic aqueous pressure-sensitive adhesive of the present invention.

  Other dispersion stabilizers other than the emulsifier include, for example, polyvinyl alcohol (PVA), fiber ether, starch, maleated polybutadiene, maleated alkyd resin, polyacrylic acid (salt), polyacrylamide, and aqueous acrylic resin. Examples thereof include synthetic or natural water-soluble polymer substances such as water-based polyester resins, water-based polyamide resins, and water-based polyurethane resins, and these may be used alone or in combination of two or more.

  The method for producing the acrylic water-based pressure-sensitive adhesive of the present invention is basically a method for obtaining a water-dispersed acrylic polymer by emulsion polymerization. For example, (1) water, a polymerizable monomer component , A method of emulsion polymerization by mixing a polymerization initiator, if necessary, an emulsifier and a dispersion stabilizer, (2) a mixture of water, a polymerizable monomer component, and an emulsifier in advance and a polymerization initiator in parallel So-called pre-emulsion method, (3) water, polymerizable monomer component, polymerization initiator, and if necessary, emulsifier and dispersion stabilizer are separately supplied in parallel and emulsion polymerization Among these methods, method (2) is preferable because polymerization stability is better.

  In these methods for producing the acrylic aqueous pressure-sensitive adhesive of the present invention, the radical generation amount (Rd) may be controlled from the beginning of the emulsion polymerization, and among them, the polymerizable monomer component and the polymerization initiator (X It is preferable to carry out emulsion polymerization using a part of each of the above to prepare a dispersion of resin particles in the initial stage, and then perform emulsion polymerization with the radical generation amount (Rd) controlled using this as a seed. The amount of the polymerizable monomer component used at that time is preferably in the range of 0.3 to 5% by weight of the total amount of the polymerizable monomer components, and the radical generation amount is not limited, but 80% of the polymerization initiator. It is preferable to react until the above is consumed.

  In addition to the above methods (1) to (3), for example, as a method (4), there is a method in which a part of an emulsion prepared in advance is dropped and then a reactive emulsifier is dropped together with the remaining emulsion. This method (4) not only improves the polymerization stability compared to the above-mentioned methods (1) to (3), but also has a better water resistance of the film formed from the resulting acrylic aqueous pressure-sensitive adhesive. Therefore, it is more preferable.

  The method (4), which is a more effective method for producing the acrylic aqueous pressure-sensitive adhesive of the present invention, will be described in more detail.

  In the method (4) for producing the acrylic aqueous pressure-sensitive adhesive of the present invention, an emulsion containing a polymerizable monomer component and a surfactant is continuously or dividedly supplied into a reaction vessel containing an aqueous medium and reacted. And a reaction step (I) in which 10 to 90% by weight of the total supply amount of the emulsion is supplied and reacted, and a reaction step (II) in which the remaining amount of the emulsion and polymerization are performed. And a step of supplying and reacting a surfactant (that is, a reactive emulsifier) containing a polymerizable monomer component and a polymerizable unsaturated group in the molecule simultaneously or continuously.

  At this time, the method of supplying the reactive emulsifier to be added later, that is, the reactive emulsifier to be added in the reaction step (II) is not particularly limited, and is mixed with the remaining emulsion or supplied separately or separately from the emulsion. The method of supplying into the reaction vessel in parallel with the above may be selected as appropriate.

  Moreover, there is no restriction | limiting in particular in the kind of reactive emulsifier used by reaction process (II), Although it can select and use arbitrarily from the above-mentioned reactive emulsifier, among these, following general formula (1a) or (1b) If the reactive emulsifier represented by) is used, the reason is not clear, but an effect that is excellent in adhesive force (that is, rough surface adhesiveness) is obtained even on uneven surfaces such as urethane foam. Is more preferable.

  As a commercial item of the reactive emulsifier represented with the following general formula (1a), Aqualon KH-05 [made by Daiichi Kogyo Seiyaku Co., Ltd.], KH-10 [made by the company], etc. are mentioned, for example. Moreover, as a commercial item of the reactive emulsifier represented by the following general formula (1b), for example, Aqualon HS-10 [Daiichi Kogyo Seiyaku Co., Ltd.], HS-20 [made by the company], BC-05 [the company] Product], BC-10 [manufactured by the company], BC-20 [manufactured by the company], and the like.

(In the formula, R is an alkyl group having a straight chain structure, a branched structure or a cyclic structure having 6 to 18 carbon atoms, and n represents an integer of 3 to 150.)

  The proportion of the emulsion (remaining emulsion) to which the reactive emulsifier represented by the general formula (1a) or (1b) is added is in the range of 10 to 90% by weight of all the emulsions, preferably 20 It is in the range of ˜80% by weight, more preferably 30 to 70% by weight. If the ratio of the emulsion (remaining emulsion) to which the reactive emulsifier is added is within such a range, particularly excellent adhesive force (that is, rough surface adhesion) even on rough surfaces such as urethane foam. Can be obtained.

  The method for supplying the polymerization initiator (X) is, for example, a method in which the polymerization initiator is constantly controlled at a constant rate [a constant radical generation amount (Rd)], a method in which the supply rate is gradually changed, and the polymerization described above. A method in which a reactive monomer component is dividedly supplied in reaction step (I) and reaction step (II) and a polymerization initiator is supplied at different rates in reaction step (I) and reaction step (II), etc. Any method is not particularly limited as long as it is controlled and supplied so as to be within the range of the radical generation amount (Rd). Among these supply methods, a method of supplying while always controlling at a constant rate [a constant radical generation amount (Rd)] is preferable because good polymerization stability is obtained and the control of the polymer structure is easy.

  The average particle size of the emulsion particles contained in the acrylic aqueous pressure-sensitive adhesive of the present invention is not particularly limited, but is preferably in the range of 50 to 1000 nm. The “average particle diameter of emulsion particles” as used in the present invention refers to the 50% median diameter of emulsion particles based on the volume, and is based on the value obtained by the dynamic light scattering method described in the examples. .

  The solid content concentration of the acrylic aqueous pressure-sensitive adhesive of the present invention is not particularly limited, but is preferably in the range of 40 to 70% by weight. When the solid content concentration is within such a range, the workability during production and the drying property during use are excellent.

  The acrylic water-based pressure-sensitive adhesive of the present invention has, for example, adhesion to an adherend having an uneven surface such as urethane foam, or a low-polar adherend such as a polyolefin-based material, and resistance to peeling. For the purpose of improving the physical properties, it is preferable to add a tackifier resin (D).

  The addition amount of the tackifying resin (D) is preferably in the range of 5 to 50% by weight, more preferably in the range of 10 to 40% by weight with respect to the acrylic polymer (P). If the addition amount of the tackifying resin is within such a range, it is possible to obtain a good balance between excellent adhesive strength and peeling resistance.

  The tackifier resin (D) is not particularly limited, and examples thereof include petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, and alicyclic petroleum resins; rosin resins, rosin ester resins, Rosin resins such as leveled rosin resin, polymerized rosin resin, polymerized rosin ester resin, rosin phenol resin; terpene resins such as terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene phenol resin, etc. These may be used alone or in combination of two or more. Among these, the use of a terpene resin is particularly preferable because it can achieve both rough surface adhesion and peeling resistance.

  Examples of commercially available tackifier resins (D) include Superester E-720 (manufactured by Arakawa Chemical Co., Ltd.), Superester E-730-55 (manufactured by the company), Superester E-788 (manufactured by the company). , Superester E-865 (manufactured by the company), Superester E-865NT (manufactured by the company), Tamanol E-100 (manufactured by the company), Tamanoru E-200 (manufactured by the company), Tamanol E-200NT (manufactured by the company), Harrier Star SK-816E (manufactured by Harima Kasei Co., Ltd.), Harrier Star SK-816E (manufactured by the company), Harrier Star SK-822E (manufactured by the company), Harrier Star SK-370N (manufactured by the company), and the like can be mentioned. You may use 2 or more types together.

  In addition, the acrylic aqueous pressure-sensitive adhesive of the present invention includes, for example, a filler, a pigment, a pH adjuster, a film forming aid, a leveling agent, a thickener, a water repellent, as long as the desired effects of the present invention are not impaired. Known additives such as agents and antifoaming agents can be used in combination.

  The acrylic water-based pressure-sensitive adhesive of the present invention can be used, for example, in various pressure-sensitive adhesive products composed of a base material and a layer of acrylic water-based pressure-sensitive adhesive (may have a multilayer structure).

  The substrate is not particularly limited, and examples thereof include various organic and inorganic materials such as paper, plastic film, nonwoven fabric, knitted fabric, woven fabric, metal, glass material (glass plate, glass fiber, etc.), ceramic, and the like. Can be mentioned.

  The method for forming the pressure-sensitive adhesive layer of the acrylic aqueous pressure-sensitive adhesive of the present invention is not particularly limited. For example, a direct method in which the acrylic water-based pressure-sensitive adhesive is directly coated on a substrate and dried; silicone The aqueous adhesive is coated on a release material such as paper or plastic film treated with a release agent such as a compound or a fluorine compound, and dried to form an adhesive layer. And a method of transferring the pressure-sensitive adhesive layer onto the base material.

  Although it does not specifically limit as a coating method, For example, the method of using a roll coater, a comma coater, a lip coater, a fountain die coater, a gravure coater etc. as a coating machine is mentioned.

  The properties (solid content concentration, viscosity, pH) of the acrylic aqueous pressure-sensitive adhesive of the present invention may be appropriately set and are not particularly limited, but preferably the solid content concentration is in the range of 40 to 70% by weight and the viscosity is 10%. It is the range of -10,000 mPa * s (BM type viscometer, 60 rotations / minute, 25 degreeC), and the range of pH 6-9.

  In addition, in the case of coating by the above direct method, although depending on the type of coating method, in general, a low viscosity is often required for coating at a higher speed. Moreover, when applying by the said transfer method, a thing with a viscosity of 300-10,000 mPa * s (same as above) is preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples. In the following, unless otherwise specified, “%” represents “% by weight”, and “part” represents “part by weight”.

[Calculation method of radical generation amount (Rd)]
The radical generation amount (Rd) generated per minute per liter of the polymerizable monomer component present in the reaction system was determined by the following formula.
Rd (mol / l / min) = c / 2 / t / 60
c: Concentration of polymerization initiator (mol / l)
t: Half-life (hr)
The half-life (t) in the above formula was determined by the following formula.
t = ln2 / k
k: Decomposition rate constant The decomposition rate constant (k) was determined from the following Arrhenius equation.
k = A × exp (−ΔE / RT)
A: frequency factor ΔE; activation energy (J / mol)
R: Gas constant T: Temperature (K)

[Measurement method of gel fraction]
The acrylic aqueous pressure-sensitive adhesive obtained in Examples below was applied to the surface of a 25 μm-thick polyethylene terephthalate (PET) film so that the film thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes for adhesion. A sheet was prepared and cut into a size of 50 mm × 50 mm as a sample. Next, the weight (G ₁ ) of the sample before immersion in toluene and the weight (G ₀ ) before application of the adhesive (base material only) were measured in advance, and immersed in a toluene solution at room temperature for 24 hours. And the toluene insoluble part of the sample after immersion is separated by filtering with a 300 mesh wire mesh, the weight (G ₂ ) of the residue after drying at 110 ° C. for 1 hour is measured, and the gel fraction is determined according to the following formula: Asked.
Gel fraction (wt%) = _{[(G 2 -G 0) / (} G 1 -G 0) ] × 100

[Measurement method of glass transition temperature (Tg)]
The water-dispersed acrylic polymer obtained in the examples described later was applied to a glass plate so that the film thickness after drying was 0.3 mm, dried at 25 ° C. for 24 hours, and then peeled off from the glass plate. Samples dried at 100 ° C. for 5 minutes were weighed in an aluminum cylindrical cell having a diameter of 5 mm and a depth of 2 mm, and a DSC-2920 modulated differential scanning calorimeter [TA Instruments Inc. The endothermic curve was measured when the temperature was raised from −150 ° C. to 100 ° C. at a rate of temperature increase of 20 ° C./min in a nitrogen atmosphere.

[Measurement method of average particle size]
The average particle diameter (50% median diameter on a volume basis) measured with a Microtrac UPA type particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd.) was determined.

[Method of evaluating emulsion stability]
A predetermined amount of an epoxy compound was blended with the synthesized aqueous resin dispersion as a crosslinking agent and stirred to prepare an acrylic aqueous adhesive. The obtained acrylic water-based pressure-sensitive adhesive was allowed to stand in a thermostatic bath at 25 ° C., and the viscosity stability of the emulsion was evaluated based on whether or not the viscosity of the acrylic water-based pressure-sensitive adhesive changed after 72 hours.
A: The viscosity is not changed.
○: Slightly thickened.
(Triangle | delta): Although extreme thickening is recognized, there exists fluidity | liquidity.
X: Gelled and not fluid.

[Measurement method of adhesive strength]
The acrylic aqueous pressure-sensitive adhesive obtained in Examples below was applied to the surface of a PET film having a thickness of 25 μm so that the film thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes to prepare a pressure-sensitive adhesive sheet. . Using an adhesive sheet and a stainless steel plate with a mirror finish as the adherend, the 180 ° peel strength was measured in an atmosphere of 23 ° C. and 50% relative humidity in accordance with JIS Z-0237 to evaluate the adhesive strength.

[Evaluation method of rough surface adhesion (adhesion to urethane foam)]
The acrylic aqueous pressure-sensitive adhesive obtained in Examples below was applied to the surface of a PET film having a thickness of 25 μm so that the film thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes to prepare a pressure-sensitive adhesive sheet. . This substrate was bonded to an ECS urethane foam in an atmosphere of 23 ° C. and 50% relative humidity with a 2 kg roll, and immediately after that, it was slowly peeled off by hand, and the destruction state of the urethane foam surface at that time was visually observed. Evaluation was made according to the following criteria.
A: The urethane foam surface was almost completely destroyed.
○: The surface of the urethane foam was slightly broken, and part of the surface was transferred to the pressure-sensitive adhesive layer.
Δ: The urethane foam surface was transferred slightly to the pressure-sensitive adhesive layer.
X: The surface of the urethane foam was not transferred to the pressure-sensitive adhesive layer, and the original shape was retained.

[Method of measuring holding force]
Create a pressure-sensitive adhesive sheet in the same way as when measuring the adhesive strength, affix the pressure-sensitive adhesive sheet to the stainless steel plate so that the bonding area is 25 mm x 25 mm, apply a 1 kg load at 40 ° C, and measure the time until slipping off The holding time was defined as holding force. Moreover, when it was hold | maintained after 12 hours, the holding time was made into 12 hours or more, the shift | offset | difference width from the initial sticking position was measured, and it described together.

[Tack measurement method]
A pressure-sensitive adhesive sheet was prepared in the same manner as the measurement of adhesive force, and measured in an atmosphere of 23 ° C. and 50% relative humidity according to the ball rolling method of JIS Z-0237.

[Example 1]
(1) Preparation of Emulsified Liquid (Ia) 10 parts of Latemul E-118B [manufactured by Kao Corporation; active ingredient 25%] as an emulsifier and 100 parts of deionized water were uniformly dissolved in a container. The alkyl (meth) acrylate (B) having an alkyl group having 1 to 12 carbon atoms [hereinafter abbreviated as alkyl (meth) acrylate (B). ] 2-ethylhexyl acrylate 300 parts, n-butyl acrylate 150 parts, methyl methacrylate 40 parts, carboxyl group-containing ethylenically unsaturated monomer (A) [hereinafter abbreviated as unsaturated monomer (A). ] 10 parts of acrylic acid and 1 part of lauryl mercaptan were added and emulsified to obtain an emulsion (Ia).
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 85 ° C. while blowing nitrogen. Warm up. Under stirring, 10 parts of an aqueous potassium persulfate solution (solid content 0.5%) was added, and then 6.1 parts of an emulsion (Ia) was charged and polymerized in 1 hour while maintaining 85 ° C. to obtain resin particles. Then, using this as a seed, 604.9 parts of the remaining emulsion (Ia) and 45 parts of aqueous potassium persulfate solution (solid content 1%) were reacted using separate dropping funnels. While keeping the container at 85 ° C., the polymerization was carried out dropwise over 6 hours.
After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, then the contents were cooled, adjusted with aqueous ammonia (active ingredient 10%) so that the pH was 8.0, and this was filtered through a 200 mesh wire net, A water-dispersed acrylic polymer (P) was obtained. Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 1 shows the transition temperature (Tg) and the gel fraction.
(2) Manufacture of acrylic water-based pressure-sensitive adhesive (II-a) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, TETRAD-C [Mitsubishi Gas Chemical Co., Ltd .; active ingredient 100%] 0.3 parts as crosslinker oil-soluble epoxy compound (C), Tamanor E-100 [Arakawa as tackifier resin (D) Chemical Industry Co., Ltd .; active ingredient 52%] 250 parts were added and stirred for 1 hour, followed by filtration through a 100 mesh wire mesh to obtain the acrylic aqueous pressure-sensitive adhesive (II-a) of the present invention. Stability of this acrylic water-based pressure-sensitive adhesive (II-a), and the gel fraction (toluene-insoluble fraction) of the film obtained using the acrylic water-based pressure-sensitive adhesive, the adhesive strength of the pressure-sensitive adhesive sheet, the rough surface adhesive strength, Table 1 shows the evaluation results of holding force and tack.

[Example 2]
(1) Preparation of Emulsified Liquid (Ib-1) and Emulsified Liquid (Ib-2) 10 parts of Latemul E-118B (manufactured by Kao Corporation; active ingredient 25%) and deionized as an emulsifier in a container 100 parts of water was added and dissolved uniformly. There, 200 parts of 2-ethylhexyl acrylate as alkyl (meth) acrylate (B), 250 parts of n-butyl acrylate, 25 parts of methyl methacrylate, 25 parts of acrylic acid as unsaturated monomer (A), and lauryl mercaptan. 5 parts was added and emulsified to obtain an emulsified liquid (Ib-1).
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 60 ° C. while blowing nitrogen. Warm up. Under stirring, 10 parts of an aqueous ammonium persulfate solution (solid content: 1%) was added, and then 6.1 parts of an emulsion (Ib-1) was charged and polymerized in 1 hour while maintaining 60 ° C. After producing the dispersion, a part (302.2 parts) of the remaining emulsion (Ib-1) and 22.5 parts (2% active ingredient) of an aqueous ammonium persulfate solution were separately separated using this as a seed. Using a dropping funnel, polymerization was carried out by dropping over 3 hours while keeping the reaction vessel at 60 ° C. During this time, 5 parts of Aqualon KH-10 [Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 100%], which is a reactive emulsifier, is added to the emulsion (Ib-1) (302.2 parts) that was not added dropwise. The mixture was stirred until it became uniform to prepare an emulsion (Ib-2).
Immediately after the completion of the dropwise addition of the emulsion (Ib-1), 307.2 parts of the emulsion (Ib-2) and 22.5 parts of an aqueous ammonium persulfate solution (2% active ingredient) were placed in separate dropping funnels. Using the reaction vessel, the polymerization was carried out dropwise over 3 hours while keeping the reaction vessel at 60 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 1 shows the transition temperature (Tg) and the gel fraction.
(2) Manufacture of acrylic water-based pressure-sensitive adhesive (II-b) Surfinol 420 [manufactured by Air Products Japan Co., Ltd .; active ingredient 100%] 1.2 as a leveling agent in the above water-dispersed acrylic polymer Part, 0.1 part of TETRAD-C [Mitsubishi Gas Chemical Co., Ltd .; active ingredient 100%] as the oil-soluble epoxy compound (C) of the crosslinking agent, 150 parts of Tamanol E-100 as the tackifier resin (D), and After adding 150 parts of Super Ester E-788 (Arakawa Chemical Industries, Ltd .; active ingredient 50%) and stirring for 1 hour, the mixture was filtered through a 100 mesh wire mesh, and the acrylic aqueous adhesive (II-b) of the present invention was added. Obtained. Stability of the acrylic water-based pressure-sensitive adhesive (II-b), gel fraction of the film obtained using the acrylic water-based pressure-sensitive adhesive (toluene-insoluble fraction), adhesive strength of the pressure-sensitive adhesive sheet, rough surface adhesive strength Table 1 shows the evaluation results of the holding force and tack.

Example 3
(1) Preparation of Emulsified Liquid (Ic-1) and Emulsified Liquid (Ic-2) 10 parts of Latemul E-118B [manufactured by Kao Corporation; active ingredient 25%] and deionized as an emulsifier in a container 100 parts of water was added and dissolved uniformly. Then, 435 parts of 2-ethylhexyl acrylate as alkyl (meth) acrylate (B), 50 parts of methyl methacrylate, 15 parts of acrylic acid as unsaturated monomer (A), and 1 part of lauryl mercaptan were added to emulsify, and emulsify. A liquid (Ic-1) was obtained.
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 270 parts of deionized water were added, and the temperature was raised to 75 ° C. while blowing nitrogen. Warm up. Under stirring, 10 parts of an aqueous potassium persulfate solution (solid content 0.5%) was added, and then 6.1 parts of an emulsion (Ic-1) was charged and polymerized in 1 hour while maintaining 75 ° C. After producing a dispersion of resin particles, using this as a seed, a part (423.4 parts) of the remaining emulsion (Ic-1) and 66.5 parts of an aqueous potassium persulfate solution (active ingredient 1) %) Was polymerized dropwise over 4.5 hours using a separate dropping funnel while keeping the reaction vessel at 75 ° C. During this time, Aqualon KH-0530 (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 30%) 1.5 parts which is a reactive emulsifier is added to the emulsion (Ic-1) (181.5 parts) which was not dripped. And stirred until uniform to prepare an emulsion (Ic-2).
Immediately after the dropping of the emulsion (Ic-1), the emulsion (Ic-2) (183 parts) and the potassium persulfate aqueous solution 28.5 parts (active ingredient 1%) were put into separate dropping funnels. Using the reaction vessel, the polymerization was carried out dropwise over 1.5 hours while keeping the reaction vessel at 75 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 1 shows the transition temperature (Tg) and the gel fraction.
(2) Production of acrylic water-based pressure-sensitive adhesive (II-c) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, 0.3 parts of Denacol EX-201 (manufactured by Nagase Chemicals Co., Ltd .; active ingredient 100%) as an oil-soluble epoxy compound (C) as a crosslinking agent was added and stirred for 1 hour. Filtration was performed to obtain an acrylic aqueous pressure-sensitive adhesive (II-c) of the present invention. Stability of the acrylic aqueous pressure-sensitive adhesive (II-c), gel fraction of the film obtained using the acrylic aqueous pressure-sensitive adhesive (toluene-insoluble fraction), adhesive strength of adhesive sheet, rough surface adhesive strength Table 1 shows the evaluation results of the holding force and tack.

Example 4
(1) Preparation of Emulsified Liquid (Id-1) and Emulsified Liquid (Id-2) In a container, 10 parts of Latemul E-118B (manufactured by Kao Corporation; active ingredient 25%) and deionized as an emulsifier 100 parts of water was added and dissolved uniformly. Thereto, 250 parts of 2-ethylhexyl acrylate, 230 parts of n-butyl acrylate as alkyl (meth) acrylate (B), 20 parts of acrylic acid as unsaturated monomer (A), and 0.5 part of lauryl mercaptan were added. The mixture was emulsified to obtain an emulsion (Id-1).
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 45 ° C. while blowing nitrogen. Warm up. Under stirring, 10 parts of an aqueous ammonium persulfate solution (5% solids) was added, and then 6.1 parts of an emulsion (Id-1) was charged and polymerized in 1 hour while maintaining 45 ° C. After producing the dispersion, using this as a seed, a part (90.7 parts) of the remaining emulsion (Id-1) and 6.75 parts of an aqueous ammonium persulfate solution (10% active ingredient) Using a separate dropping funnel, polymerization was carried out by dropping over 1 hour while keeping the reaction vessel at 45 ° C. During this time, 3 parts of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 100%), which is a reactive emulsifier, is added to the emulsion (Id-1) (513.7 parts) that was not dripped. The mixture was stirred until it became uniform to prepare an emulsion (Id-2).
Immediately after completion of the dropwise addition of the emulsion (Id-1), separate the emulsion (Id-2) (516.7 parts) and 38.25 parts of an aqueous ammonium persulfate solution (10% active ingredient) in separate dropping funnels. Was used for dropwise polymerization over 5 hours while keeping the reaction vessel at 45 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer. Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 1 shows the transition temperature (Tg) and the gel fraction.
(2) Production of acrylic water-based pressure-sensitive adhesive (II-d) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, TETRAD-C [Mitsubishi Gas Chemical Co., Ltd .; active ingredient 100%] 0.1 part as an oil-soluble epoxy compound (C) as a crosslinking agent, superester E-788 [Tackifier resin (D) as [D] Arakawa Chemical Industries, Ltd .; active ingredient 50%] 150 parts were added and stirred for 1 hour, followed by filtration through a 100 mesh wire netting to obtain the acrylic aqueous pressure-sensitive adhesive (II-d) of the present invention. Stability of this acrylic water-based pressure-sensitive adhesive (II-d), gel fraction (toluene-insoluble fraction) of the film obtained using this acrylic water-based pressure-sensitive adhesive, adhesive strength of adhesive sheet, rough surface adhesive strength Table 1 shows the evaluation results of the holding force and tack.

Example 5
(1) Preparation of Emulsified Liquid (Ie-1) and Emulsified Liquid (Ie-2) 10 parts of Latemul E-118B [manufactured by Kao Corporation; active ingredient 25%] and deionized as an emulsifier in a container 100 parts of water was added and dissolved uniformly. Thereto, 130 parts of 2-ethylhexyl acrylate, 350 parts of n-butyl acrylate as alkyl (meth) acrylate (B), 20 parts of acrylic acid as unsaturated monomer (A), and 0.5 part of lauryl mercaptan were added. The mixture was emulsified to obtain an emulsion (Ie-1).
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 65 ° C. while blowing nitrogen. Warm up. While stirring, 10 parts of a 4,4-azobis (4-cyanovaleric acid) aqueous solution (neutralized with aqueous ammonia and dissolved; the same applies hereinafter) (solid content 1.5%) was added, followed by emulsion (I- After charging 6.1 parts of e-1) and polymerizing in 1 hour while maintaining 65 ° C. to produce a dispersion of resin particles, the remaining emulsion (I-e-1) Part (242 parts) and 18 parts of an aqueous solution of 4,4-azobis (4-cyanovaleric acid) (solid content: 3%) were added over 2 hours while maintaining the reaction vessel at 65 ° C. using a separate dropping funnel. The solution was dropped and polymerized. During this time, 4 parts of Aqualon KH-0530 (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 30%), which is a reactive emulsifier, is added to the emulsion (Ie-1) (362.4 parts) that was not dripped. The mixture was stirred until it became uniform to prepare an emulsion (Ie-2).
Immediately after completion of the dropwise addition of the emulsion (Ie-1), the emulsion (Ie-2) (366.4 parts) and 27 parts of 4,4-azobis (4-cyanovaleric acid) (solid content 3) %) Was dropped and polymerized over 4 hours using a separate dropping funnel while keeping the reaction vessel at 65 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 1 shows the transition temperature (Tg) and the gel fraction.
(2) Production of acrylic water-based pressure-sensitive adhesive (II-e) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, TETRAD-C [Mitsubishi Gas Chemical Co., Ltd .; active ingredient 100%] 0.2 parts as crosslinker oil-soluble epoxy compound (C), Tamanor E-100 [Arakawa as tackifier resin (D) 100 parts by chemical industry; active ingredient 52%] and 100 parts of super ester E-730-55 [manufactured by Arakawa Chemical Industries; 55% active ingredient] were added and stirred for 1 hour. Filtration was performed to obtain an acrylic aqueous pressure-sensitive adhesive (II-e) of the present invention. Stability of this acrylic water-based pressure-sensitive adhesive (II-e), gel fraction (toluene insoluble fraction) of the film obtained using the acrylic water-based pressure-sensitive adhesive, and adhesive strength and rough surface adhesive strength of the pressure-sensitive adhesive sheet Table 1 shows the evaluation results of the holding force and tack.

[Comparative Example 1]
(1) Preparation of Emulsified Liquid (If-1) and Emulsified Liquid (If-2) 10 parts of Latemul E-118B (manufactured by Kao Corporation; active ingredient 25%) and deionized as an emulsifier in a container. 100 parts of water was added and dissolved uniformly. There, 240 parts of 2-ethylhexyl acrylate as alkyl (meth) acrylate (B), 245 parts of n-butyl acrylate, 15 parts of acrylic acid as unsaturated monomer (A), and other ethylenically unsaturated monomers 0.5 part of γ-methacrylopropyltrimethoxysilane and 0.5 part of lauryl mercaptan were added and emulsified to obtain an emulsion (If-1).
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 55 ° C. while blowing nitrogen. Warm up. Under stirring, 10 parts of an aqueous ammonium persulfate solution (solid content: 1%) was added, and then 6.1 parts of an emulsion (If-1) was charged and polymerized in 1 hour while maintaining 55 ° C. Subsequently, a part (362.9 parts) of the remaining emulsion (If-1) and 27 parts of an aqueous ammonium persulfate solution (2% active ingredient) were placed in a reaction vessel at 60 ° C. using a separate dropping funnel. The polymerization was carried out dropwise over 4 hours while maintaining the temperature. During this time, 4 parts of Aqualon KH-0530 (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 30%), which is a reactive emulsifier, is added to the emulsion (If-1) (242 parts) that was not added dropwise, and uniform. The mixture was stirred until an emulsion (If-2) was prepared.
Immediately after completion of the dropwise addition of the emulsion (If-1), the emulsion (If-2) (246 parts) and 18 parts of an aqueous ammonium persulfate solution (2% active ingredient) were separately added using a dropping funnel. While maintaining the reaction vessel at 55 ° C., dropwise polymerization was performed over 2 hours. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). The solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and the glass transition temperature of the coating obtained from the water-dispersed acrylic polymer ( Tg) and the gel fraction are shown in Table 2.
(2) Production of acrylic water-based pressure-sensitive adhesive (II-f) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, 250 parts of Tamanol E-100 [Arakawa Chemical Industries, Ltd .; active ingredient 52%] as an tackifier resin (D) was added and stirred for 1 hour, then filtered through a 100 mesh wire net and an acrylic aqueous adhesive. Agent (II-f) was obtained. Stability of this acrylic water-based pressure-sensitive adhesive, gel fraction (toluene insoluble fraction) of the film obtained using this acrylic water-based pressure-sensitive adhesive, and adhesive strength, rough surface adhesive strength, holding strength, tack of the pressure-sensitive adhesive sheet The evaluation results are shown in Table 2.

[Comparative Example 2]
(1) Preparation of Emulsified Liquid (Ig-1) and Emulsified Liquid (Ig-2) In a container, 10 parts of Latemul E-118B (manufactured by Kao Corporation; active ingredient 25%) and deionized as an emulsifier 100 parts of water was added and dissolved uniformly. Thereto, 180 parts of 2-ethylhexyl acrylate as alkyl (meth) acrylate (B), 300 parts of n-butyl acrylate, 20 parts of acrylic acid as unsaturated monomer (A), and 1 part of lauryl mercaptan were added and emulsified. The emulsion (Ig-1) was obtained.
In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel, 0.2 part of emulsifier Latemul E-118B and 320 parts of deionized water were added, and the temperature was raised to 65 ° C. while blowing nitrogen. Warm up. While stirring, 10 parts of a 4,4-azobis (4-cyanovaleric acid) aqueous solution (neutralized with aqueous ammonia and dissolved; the same applies hereinafter) (solid content 1%) was added, followed by emulsion (I-g-1 ) Was charged in 6.1 parts and polymerized in 1 hour while maintaining 65 ° C. Subsequently, a part (242 parts) of the remaining emulsion (I-g-1) and 18 parts (active ingredient 2%) of an aqueous solution of 4,4-azobis (4-cyanovaleric acid) were added to a separate dropping funnel. The reaction vessel was used and polymerized dropwise over 2 hours while maintaining the reaction vessel at 65 ° C. During this time, 3 parts of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd .; active ingredient 100%), which is a reactive emulsifier, was added to the emulsion (Ig-1) (362.9 parts) that was not added dropwise. The mixture was stirred until it became uniform to prepare an emulsion (Ig-2).
Immediately after completion of the dropwise addition of the emulsion (Ig-1), the emulsion (Ig-2) (365.9 parts) and 27 parts of 4,4-azobis (4-cyanovaleric acid) aqueous solution (active ingredients) 2%) was dropped and polymerized over 4 hours using a separate dropping funnel while keeping the reaction vessel at 65 ° C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 2 hours, and then the contents were cooled and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 2 shows the transition temperature (Tg) and the gel fraction.
(2) Manufacture of acrylic water-based pressure-sensitive adhesive (II-g) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above 1.2 parts, Denacol EX-614B (manufactured by Nagase Kasei Kogyo Co., Ltd .; active ingredient 100%) as a crosslinking agent as a crosslinking agent 0.4 part, Tamanor E-100 [Arakawa as a tackifier resin (D) 100 parts by Chemical Industry Co., Ltd .; active ingredient 50%] and 100 parts Superester E-730-55 [Arakawa Chemical Industries, Ltd .; 55% active ingredient] were added and stirred for 1 hour. Filtration gave an acrylic aqueous adhesive (II-g). Stability of this acrylic water-based pressure-sensitive adhesive (II-g), gel fraction (toluene-insoluble fraction) of a film obtained using the acrylic water-based pressure-sensitive adhesive, and adhesive strength and rough surface adhesive strength of the pressure-sensitive adhesive sheet Table 2 shows the evaluation results of the holding force and tack.

[Comparative Example 3]
(1) Production of dispersion (Ih-1) In a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a condenser (cooling tube), a raw material charging port, and a thermometer, deionized at 25 ° C. 75 parts of water was charged, and nitrogen gas was introduced at a flow rate of 50 ml / min from a nitrogen introduction tube with stirring. After 120 minutes, the dissolved oxygen concentration in the reaction vessel was measured and found to be 2.3 ppm. While introducing nitrogen gas under stirring in the reaction vessel, 1 part of polyoxyethylene nonylphenyl ether [HLB = 14], 1 part of sodium dodecylbenzenesulfonate, 70 parts of 2-ethylhexyl acrylate, 27 parts of ethyl acrylate, acrylic 5 parts of acid was charged and the whole was uniformly emulsified. Thereafter, the temperature in the reaction vessel was adjusted to 50 ° C. Next, after confirming that the temperature in the reaction vessel was 50 ° C., 0.02 part of 2,2-azobis [2-methyl-N- (phenylmethyl) -propionamidine] dihydrochloride was added, and the mixture was heated to 50 ° C. After carrying out emulsion polymerization by maintaining for 8 hours, the content was cooled to obtain a dispersion (Ih-1).

(2) Preparation of emulsion (Ih-2) First, 4 parts of polyoxyethylene nonylphenyl ether [HLB = 14], 4 parts of sodium dodecylbenzenesulfonate, and 60 parts of deionized water were added to the container. Dissolved in. Thereto, 280 parts of 2-ethylhexyl acrylate, 108 parts of ethyl acrylate, and 10 parts of acrylic acid were charged, and the whole was uniformly emulsified to obtain an emulsion (Ih-2).
To a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a condenser (cooling tube), a raw material charging port, and a thermometer, a solution obtained by dissolving 280 parts of deionized water at 25 ° C. and 1 part of ammonium persulfate in 40 parts of water was added. Warm to 70 ° C. with displacement. The above-mentioned emulsion (Ih-2) was dropped and polymerized over 3 hours using a dropping funnel. After completion of the dropwise addition, the contents were cooled after stirring for 2 hours at the same temperature.
After cooling, a separately synthesized dispersion (Ih-1) was mixed in the same reaction vessel, and adjusted with aqueous ammonia (10% active ingredient) so that the pH was 8.0. This was filtered through a 200-mesh wire mesh to obtain a water-dispersed acrylic polymer (P). Solid content concentration, viscosity, average particle diameter, weight average molecular weight (Mw) of the water-dispersed acrylic polymer (P) obtained here, and glass of the coating obtained from the water-dispersed acrylic polymer (P) Table 2 shows the transition temperature (Tg) and the gel fraction.
(3) Production of acrylic water-based pressure-sensitive adhesive (II-h) Surfinol 420 [manufactured by Air Products Japan; active ingredient 100%] as a leveling agent to the water-dispersed acrylic polymer (P) described above After adding an aqueous solution in which 0.025 part of TEPIC (manufactured by Nissan Chemical Industries, Ltd.) as an epoxy crosslinking agent in 1 part of water was added to 2.4 parts, the mixture was filtered through a 100-mesh wire mesh and an acrylic aqueous adhesive (II -H) was obtained. Stability of this acrylic water-based pressure-sensitive adhesive (II-h), gel fraction (toluene-insoluble fraction) of a film obtained using this acrylic water-based pressure-sensitive adhesive, adhesive strength of adhesive sheet, rough surface adhesive strength Table 2 shows the evaluation results of the holding force and tack.

The names of the abbreviations in Table 1 and Table 2 are as follows.
Note 1) CVA; 4,4-azobis (4-cyanovaleric acid)
Note 2) AMP; 2,2-azobis [2-methyl-N- (phenylmethyl) -propionamidine] dihydrochloride Note 3) γ-MPS; γ-methacryloxypropyltrimethoxysilane

The acrylic water-based pressure-sensitive adhesive of the present invention can achieve both excellent adhesive force and holding force, and is particularly excellent in adhesive force (that is, rough surface adhesiveness) even on rough surfaces having irregularities such as urethane foam. , And can be used for various adhesive products composed of a base material and an acrylic water-based adhesive layer, and the base material is not particularly limited. For example, paper, plastic film, nonwoven fabric, knitted fabric, woven fabric, Various organic and inorganic materials such as metals, glass materials (glass plates, glass fiber products, etc.), ceramics and the like can be mentioned.

Claims (5)

In the range of 0.1 to 10% by weight of the carboxyl group-containing ethylenically unsaturated monomer (A) and 45 to 99.9% by weight of alkyl (meth) acrylate (B) having an alkyl group having 1 to 12 carbon atoms. The acrylic polymer (P) obtained by emulsion polymerization of the polymerizable monomer component contained in the aqueous medium in the presence of the polymerization initiator (X) is further crosslinked with the oil-soluble epoxy compound (C). A radical generation amount (Rd) calculated on the basis of the amount of the polymerization initiator (X) used is an acrylic water-based pressure-sensitive adhesive produced per liter of polymerizable monomer component in the reaction system per minute. The range of 2 × 10 ^{−13 to} 150 × 10 ⁻¹³ mol and the gel fraction of the film formed from the acrylic polymer (P) before crosslinking is 20% by weight or less, and the oil-soluble property Gel of coating after crosslinking with epoxy compound (C) An acrylic water-based pressure-sensitive adhesive having a fraction of 10 to 50% by weight. The acrylic water-based pressure-sensitive adhesive according to claim 1, wherein a terpene-based resin is used as the tackifier resin (D). An acrylic aqueous pressure-sensitive adhesive obtained by supplying an emulsion containing a polymerizable monomer component and a surfactant into a reaction vessel in which an aqueous medium is present and allowing the emulsion to react. A reaction step (I) for reacting by supplying 90% by weight, and a surfactant (reactive emulsifier) having an unsaturated group capable of polymerizing with the remaining emulsion and the polymerizable monomer component in the molecule; The acrylic water-based pressure-sensitive adhesive according to claim 1 or 2, which is obtained by the step (II) of supplying and reacting simultaneously. Radical generation amount obtained computationally from the polymerization initiator amount used (Rd) is, per polymerizable monomer component 1 l in the reaction system, and the range of min 5 × 10 ^-13 ~120 × 10 ^-13 mol The reaction step (I) in which the emulsion is continuously supplied and reacted, and the radical generation amount (Rd) is 5 × 10 5 per minute per liter of the polymerizable monomer component in the reaction system. ^{-13 to} 120 × 10 ^-13 mol of the remaining emulsion and a surfactant having in the molecule thereof an unsaturated group capable of being polymerized with the polymerizable monomer component are continuously and continuously supplied. The acrylic water-based pressure-sensitive adhesive according to claim 3, which is obtained by the reaction step (II) that reacts as described above. The radical generation amount (Rd) calculated from the amount of polymerization initiator used is in the range of 5 × 10 ^{−13 to} 120 × 10 ⁻¹³ mol per minute per liter of the polymerizable monomer component in the reaction system. The acrylic water-based pressure-sensitive adhesive according to claim 1 or 2.