JP5349031B2 - Peelable aqueous pressure-sensitive adhesive composition, peelable aqueous pressure-sensitive adhesive, and peelable pressure-sensitive adhesive member using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a releasable aqueous adhesive composition which shows little temporal increase in adhesion strength and is excellent in non-staining property, i.e. remains few stains such as adhesive remains or marks on an adherend when released. <P>SOLUTION: The releasable aqueous adhesive composition comprises an acrylic emulsion [I] comprising an acrylic resin [A] and an emulsifier [B], provided that the emulsifier [B] comprises an anionic reactive emulsifier (b1) containing no alkylene oxide chain and an anionic non-reactive emulsifier (b2) containing no alkylene oxide chain. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an adhesive tape or sheet for temporary surface protection or temporary adhesion for preventing scratches or preventing contamination during transportation, processing, cutting, etc. of metal plates, glass plates, plastic plates, etc. The present invention relates to a release-type aqueous pressure-sensitive adhesive composition useful as an agent. More specifically, the present invention relates to a peelable water-based pressure-sensitive adhesive composition that is environmentally friendly, has little increase in adhesive strength over time, and exhibits excellent peelability even when a synthetic paper or film-based substrate is used.

Conventionally, peelable pressure-sensitive adhesive compositions have been widely used for surface protective films, coating masking tapes, adhesive seals, and the like. For example, surface protection films temporarily protect the surface of these products to prevent scratches, contamination, corrosion, etc. during transportation, processing, cutting, storage, etc. of metal products, plastic products, glass products, etc. After the purpose is reached, it is peeled off from the product surface.
Such a surface protective film adheres to the adherend during transport, processing, cutting, storage, etc. of metal products, plastic products, glass products, etc. After reaching this, the peelability is required such that it can be easily peeled off from the adherend.

  However, the pressure-sensitive adhesive tape or sheet is likely to have an increase in adhesive force due to a change over time after being attached, and as a result, it is difficult to peel off when the surface protective film is peeled off from the adherend, and the peeling work takes time. There may be problems such as adhesiveness at the time of peeling and peelability such as stain resistance after peeling, such as contamination of adhesive residue and sticking marks of the adhesive.

  In recent years, from the viewpoint of environmental hygiene, various studies have been made on water-dispersed pressure-sensitive adhesives that do not use a solvent even in a peelable pressure-sensitive adhesive composition, but sufficient adhesion to synthetic resin films and synthetic paper substrates There is a problem that it is difficult to obtain the property. As an improvement of the problem, there is a method of reducing the particle size of the obtained water-dispersed pressure-sensitive adhesive so as to fall within a specific range (for example, see Patent Document 1). In addition, as an improvement from another viewpoint, it has been proposed to use an anchor agent that improves adhesion between the base material and the pressure-sensitive adhesive layer (for example, see Patent Document 2).

  Furthermore, an emulsion [A] having a specific gel fraction obtained by emulsion polymerization of a monomer mixture having a specific composition in the presence of an anionic reactive emulsifier for the purpose of improving adhesiveness and stain resistance. And a releasable aqueous pressure-sensitive adhesive composition (for example, refer to Patent Document 3) containing a crosslinking agent [B] or a monomer mixture having a specific composition in the presence of an anionic reactive emulsifier. A re-peelable water-based pressure-sensitive adhesive composition containing emulsion [A], a cross-linking agent [B] and a phosphate ester compound [C] obtained by the above-mentioned method has been proposed (for example, see Patent Document 4). .

Japanese Patent Laid-Open No. 2005-248059 JP 2005-213280 A JP 2006-45410 A JP 2006-45411 A

However, in the technique disclosed in Patent Document 1, the viscosity of the water-dispersed pressure-sensitive adhesive composition obtained when the particle size is reduced increases, resulting in deterioration of work efficiency and generation of streaks after coating during preparation of the pressure-sensitive adhesive sheet. However, if the concentration is low, it will take a long time to dry the water that is the dispersion medium during the production of the pressure-sensitive adhesive sheet, resulting in a conflicting result that the efficiency is deteriorated. There is a problem. In the technique disclosed in Patent Document 2, an anchor agent is used, and thus costs are increased.
Further, in the disclosed techniques of Patent Documents 3 and 4, the aqueous pressure-sensitive adhesive composition has a tendency that holding power and releasability are lowered when left in an emulsion state for a long time. The substrate adhesion in the exposed state is still not satisfactory, and further improvements are required.

  Therefore, in the present invention, under such a background, the adhesiveness to various adherends is excellent, the adhesive force change with time is small, and there is no adhesive residue after peeling. A release-type aqueous pressure-sensitive adhesive composition that is excellent in storage stability as an aqueous pressure-sensitive adhesive composition, in particular, stable over time, and suitable for both a synthetic paper substrate and a film substrate, a release-type aqueous pressure-sensitive adhesive, and The object is to provide a peelable adhesive member.

  However, as a result of intensive research in view of such circumstances, the present inventors have found that a reactive emulsifier and an alkylene oxide that do not contain an alkylene oxide chain as the emulsifier in a peelable aqueous pressure-sensitive adhesive composition comprising an acrylic resin and an emulsifier. By using a non-reactive emulsifier that does not contain a chain, it is found that the pressure-sensitive adhesive composition is excellent in stain resistance, such as less adhesive force change over time with respect to the substrate and no adhesive residue after peeling. The present invention has been completed.

〔一般式（１）において、Ｒ _１ 、Ｒ _２ は水素又はアルキル基であり、同一又は異なっていてもよい。ＸはＳＯ _３ ＮＨ _４ 又はＳＯ _３ の金属塩であり、Ｙはアルキレン基である。〕

〔一般式（２）において、Ｒ _１ 、Ｒ _２ は水素又はアルキル基、Ｘ _１ 、Ｘ _２ はＳＯ _３ ＮＨ _４ 又はＳＯ _３ の金属塩である。Ｒ _１ 、Ｒ _２ 及びＸ _１ 、Ｘ _２ は、それぞれ同一又は異なっていてもよい。
〕 That is, the gist of the present invention is a peelable aqueous pressure-sensitive adhesive composition comprising an acrylic emulsion [I] containing an acrylic resin [A] and an emulsifier [B], and the acrylic resin [A] is a simple substance. It is obtained by emulsion polymerization of a monomer mixture in the presence of an emulsifier [B]. An anionic reactive emulsifier (b1) which contains a non-reactive emulsifier (b2) and does not contain an alkylene oxide chain is an emulsifier represented by the following general formula (1) and does not contain an alkylene oxide chain. The emulsifier (b2) is an emulsifier represented by the following general formula (2), an alkyl sulfate ester salt, an alkylbenzene sulfonate, an alkylsulfosuccinate, It relates releasable aqueous pressure-sensitive adhesive composition, characterized in that at least one is selected from Kill ether disulfonic acid salts.
Moreover, in this invention, the peelable water-based adhesive and peelable adhesive member which consist of the said peelable water-based adhesive composition are also provided.

[In General Formula (1), R ₁ and R ₂ are hydrogen or an alkyl group, and may be the same or different. X is a metal salt of SO ₃ NH ₄ or SO ₃ , and Y is an alkylene group. ]

[In General Formula (2), R ₁ and R ₂ are hydrogen or an alkyl group, and X ₁ and X ₂ are SO ₃ NH ₄ or a metal salt of SO ₃ . R ₁ , R ₂ and X ₁ , X ₂ may be the same or different from each other.
]

  In the present invention, the term “peeling” refers to removing once applied, and includes the meaning of re-peeling that is once applied again and then removed. Moreover, an adhesive member is a meaning including an adhesive sheet, an adhesive tape, an adhesive film, etc. Furthermore, in the present invention, the base material adhesion means that the base material adhesion during heat resistance, that is, the adhesive is not peeled off from the base material at the time of peeling after the adhesive tape or adhesive film is applied to the adherend and heated. means.

  The peelable water-based pressure-sensitive adhesive composition of the present invention is a peelable water-based pressure-sensitive adhesive composition comprising an acrylic emulsion [I] containing an acrylic resin [A] and an emulsifier [B], and the emulsifier [B]. Contains an anionic reactive emulsifier (b1) that does not contain alkylene oxide chains and an anionic non-reactive emulsifier (b2) that does not contain alkylene oxide chains. It exhibits an excellent anti-contamination effect such that there is little contamination such as glue residue and sticking marks on the body.

Hereinafter, the present invention will be specifically described.
The peelable pressure-sensitive adhesive composition of the present invention is a peelable aqueous pressure-sensitive adhesive composition comprising an acrylic emulsion [I] containing an acrylic resin [A] and an emulsifier [B], and the emulsifier [B] is an alkylene. It contains an anionic reactive emulsifier (b1) that does not contain an oxide chain and an anionic non-reactive emulsifier (b2) that does not contain an alkylene oxide chain.

The acrylic emulsion [I] is obtained by dispersing and stabilizing an acrylic resin [A] obtained by copolymerizing an acrylic monomer as a main component with an emulsifier [B]. Here, the main component means 50% by weight or more based on the entire copolymerization component.
Among them, an acrylic resin [A] having a copolymer component of a (meth) acrylic acid alkyl ester (a1) containing a C 4-12 alkyl group and a carboxyl group-containing unsaturated monomer (a2) is an emulsifier. Acrylic emulsion [I] that is dispersion-stabilized with [B] is preferable in that both high adhesive strength and good peelability can be achieved. If necessary, in addition to (meth) acrylic acid alkyl ester (a1) and carboxyl group-containing unsaturated monomer (a2) containing an alkyl group having 4 to 12 carbon atoms, other unsaturated monomers. (A3) can also be used as a copolymerization component.

  And this acrylic resin [A] is (meth) acrylic-acid alkylester (a1) and a carboxyl group-containing unsaturated monomer (a2) containing a C4-C12 alkyl group, for example as needed. Furthermore, it can be obtained by copolymerizing another unsaturated monomer (a3).

  In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate.

  Examples of the (meth) acrylic acid alkyl ester (a1) containing an alkyl group having 4 to 12 carbon atoms include n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate , Aliphatic (meth) acrylates such as undecyl (meth) acrylate, isoundecyl (meth) acrylate, dodecyl (meth) acrylate, isododecyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth ) Aromatic (meth) acrylates such as acrylate, etc. are mentioned, and among them, (meth) acrylic acid alkyl ester containing an alkyl group having 4 to 10 carbon atoms and more preferably 4 to 8 carbon atoms is preferable, specifically n-butyl. (Meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like are preferably used, and 2-ethylhexyl acrylate is particularly preferably used. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing unsaturated monomer (a2) include acrylic acid, acrylic acid dimer, methacrylic acid, crotonic acid, itaconic acid, maleic acid and the like, among which acrylic acid, methacrylic acid and the like are preferably used. It is done. These may be used alone or in combination of two or more.

  Furthermore, as other unsaturated monomer (a3), C1-C3, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, etc., for example. (Meth) acrylic acid alkyl ester having an alkyl group, (meth) acrylic acid alkyl ester having 13 or more alkyl groups such as tridecyl (meth) acrylate, isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, dimethyl Aminoethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate Le, vinyl propionate, vinyl chloride, alkyl vinyl ether.

  In addition to the above, as the unsaturated monomer (a3), a monomer that reacts with the carboxyl group-containing unsaturated monomer (a2), a monomer that can react with each other, and a self-crosslinkable functional group. Monomers having unsaturated groups such as hydroxyl group-containing unsaturated monomers, epoxy group-containing unsaturated monomers, alkoxysilyl group-containing unsaturated monomers, amide groups, methylol groups, and carbonyl groups Etc. may be used.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.
Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate and allyl glycidyl ether.

  Examples of the alkoxysilyl group-containing monomer include (meth) acryloxyethyltrimethoxysilane, (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acrylic. Roxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxy Propyldimethylethoxysilane, γ- (meth) acryloxypropyltrichlorosilane, γ- (meth) acryloxypropylmethyldichlorosilane, γ- (meth) acryloxypropyldimethylchlorosilane, γ- (meth) acryloxypropyltripropoxy Run, γ- (meth) acryloxypropylmethyldipropoxysilane, γ- (meth) acryloxypropyltributoxysilane, (meth) acryloxybutyltrimethoxysilane, (meth) acryloxypentyltrimethoxysilane, (meta ) Acryloxyhexyltrimethoxysilane, (meth) acryloxyhexyltriethoxysilane, (meth) acryloxyoctyltrimethoxysilane, (meth) acryloxydecyltrimethoxysilane, (meth) acryloxydecyltrimethoxysilane, (meth) ) Acryloxyoctadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldipropoxy Run, and the like.

  Examples of monomers containing an amide group, a methylol group, or a carbonyl group include acrylamide, methacrylamide, N-methylol acrylamide, butoxy N-methylol acrylamide, diacetone acrylamide, and 2- (acetoacetoxy) ethyl (meth) acrylate. And allyl acetoacetate.

  As the content ratio of the (meth) acrylic acid alkyl ester (a1), carboxyl group-containing unsaturated monomer (a2) and other unsaturated monomer (a3) containing the alkyl group having 4 to 12 carbon atoms. Are preferably 80 to 99.9% by weight of (meth) acrylic acid alkyl ester (a1), 0.1 to 5% by weight of carboxyl group-containing unsaturated monomer (a2), and other unsaturated monomers (A3) is 0 to 19.9% by weight, particularly preferably (meth) acrylic acid alkyl ester (a1) is 85 to 99.8% by weight, and carboxyl group-containing unsaturated monomer (a2) is 0.8. 2 to 3% by weight, other unsaturated monomer (a3) is 0 to 14.8% by weight, more preferably (meth) acrylic acid alkyl ester (a1) is 90 to 99.7% by weight, carboxyl Group-containing unsaturated single Body (a2) is 0.3 to 1.5 wt%, other unsaturated monomer (a3) is from 0 to 9.7 wt%.

  If the amount of the (meth) acrylic acid alkyl ester (a1) is too small, sufficient adhesion and tack tend not to be obtained. If the amount is too large, the amount of the carboxyl group-containing unsaturated monomer (a2) becomes small and sufficient peelability is obtained. There is a tendency not to be obtained. If the amount of the carboxyl group-containing unsaturated monomer (a2) is too small, the stability tends to decrease and the peelability tends to be insufficient. If the amount is too large, the viscosity of the emulsion increases, making it difficult to handle, and adhesive strength, tackiness There is also a tendency to decrease. Moreover, when there are too many other unsaturated monomers (a3), there exists a tendency for adhesive force and a tack to fall.

The acrylic emulsion [I] used in the present invention comprises the above (meth) acrylic acid alkyl ester (a1), carboxyl group-containing unsaturated monomer (a2), and other unsaturated monomers (if necessary) In the present invention, it is possible to stably produce a monomer mixture of copolymerization components containing (a1) to (a3) in the presence of an emulsifier [B]. It is necessary in terms of what can be done.

  The emulsifier [B] used in the present invention contains an anionic reactive emulsifier (b1) not containing an alkylene oxide chain and an anionic non-reactive emulsifier (b2) not containing an alkylene oxide chain.

Such anionic reactive emulsifier (b1), an anionic, and must be an emulsifier having a reactivity, specifically, those having the structure of the lower following general formula (1) is there.

[In the general formulas (1) and (3), R ₁ and R ₂ are hydrogen or an alkyl group, and R ₁ and R ₂ may be the same or different. X is a metal salt of SO ₃ NH ₄ or SO ₃ , and Y is an alkylene group. Y usually has 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. ]

  Specific examples of the anionic reactive emulsifier (b1) include “Eleminol JS-2”, “Eleminol JS-20” (manufactured by Sanyo Chemical Industries), “Latemul S-180A”, “Latemul S-180”. And the like (commercially available from Kao Corporation).

〔一般式（２）において、Ｒ_１、Ｒ_２は水素又はアルキル基であり、Ｘ_１、Ｘ_２はＳＯ_３ＮＨ_４又はＳＯ_３の金属塩である。Ｒ_１、Ｒ_２及びＸ_１、Ｘ_２は、同一又は異なっていてもよい。〕 The anionic non-reactive emulsifier (b2) must be an anionic emulsifier that does not have reactivity, and is specifically represented by, for example, the following general formula (2). Emulsifiers, alkyl sulfate esters, alkyl benzene sulfonates, alkyl sulfosuccinates, and alkyl diphenyl ether disulfonates . Among these, an emulsifier represented by the following general formula (2), particularly an alkyl diphenyl ether disulfonate, is preferable.

[In the general formula (2), R ₁ and R ₂ are hydrogen or an alkyl group, and X ₁ and X ₂ are SO ₃ NH ₄ or a metal salt of SO ₃ . R ₁ , R ₂ and X ₁ , X ₂ may be the same or different. ]

  Specific examples of the anionic non-reactive emulsifier (b2) include commercially available products such as “Perex SS-L” and “Neopelex G-25” (manufactured by Kao Corporation).

  About the usage-amount of the said anionic reactive emulsifier (b1) and an anionic non-reactive emulsifier (b2), it is 0.5 as a total amount with respect to 100 weight part of monomer mixtures of (a1)-(a3). It is preferably 10 to 10 parts by weight, and more preferably 0.8 to 7 parts by weight. If the amount of the emulsifier is too small, the emulsion polymerization tends to become unstable. If the amount is too large, the water resistance is lowered, and the adhesion of the substrate and the contamination of the adherend when exposed to high humidity conditions are caused. Tend to be.

  Moreover, as a mixing ratio of the anionic reactive emulsifier (b1) and the anionic nonreactive emulsifier (b2), (b1) / (b2) is preferably 0.2 to 5 (weight ratio), In particular, it is preferably 0.3 to 3 (weight ratio). If the blending ratio is out of the above range, that is, if (b1) / (b2) is too small, the polymerization stability tends to decrease, and if it is too large, the effect of the present invention tends to be difficult to obtain.

  If necessary, a nonionic non-reactive emulsifier or a nonionic reactive emulsifier can be used in combination.

  Nonionic non-reactive emulsifiers include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, oxyethylene-oxypropylene block polymer, polyoxyethylene fatty acid, glycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, And alkyl alkanolamides. In addition, an emulsifier may be added to the emulsion monomer liquid which consists of a monomer mixture, may be previously added to the superposition | polymerization can, and may use both together.

Specific examples of the nonionic reactive emulsifier include “Adekalia Soap NE-10”, “Adekalia Soap NE-20”, “Adekalia Soap NE-30”, “Adekalia Soap NE-40”, “ ADEKA rear soap ER-10, ADEKA rear soap ER-20, ADEKA rear soap ER-30, ADEKA rear soap ER-40 [above, manufactured by Asahi Denka Kogyo Co., Ltd.], AQUARON RN-10 ”,“ AQUALON RN-20 ”,“ AQUALON RN-30 ”,“ AQUALON RN-50 ”[above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.].
In addition, an emulsifier may be added to the emulsion monomer liquid which consists of a monomer mixture, may be previously added to the superposition | polymerization can, and may use both together.

  In carrying out the emulsion polymerization, it is preferable to use a polymerization initiator, and the polymerization initiator is not particularly limited, and any of water-soluble and oil-soluble can be used. Oxide, t-butyl hydroperoxide, cumene hydroperoxide, p-methane hydroperoxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, t-butylcumyl peroxide, benzoyl Peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 3,3,5- Trimethylcyclohexanone peroxide, methyl Organic peroxides such as clohexanone peroxide, di-isobutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butylperoxyisobutyrate, 2,2′-azobisisobutyronitrile, Dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), potassium persulfate, persulfate Sodium, ammonium persulfate, hydrogen peroxide, 4,4′-azobis-4-cyanovaleric acid ammonium (amine) salt, 2,2′-azobis (2-methylamidooxime) dihydrochloride, 2,2′- Azobis (2-methylbutanamide oxime) dihydrochloride tetrahydrate, 2,2'-azo {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] -propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propion Amide], various redox catalysts (in this case, as the oxidizing agent, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, etc. As the reducing agent, sodium sulfite, acidic sodium sulfite, Rongalite, ascorbic acid, etc. are used.) Among these, potassium persulfate, ammonium persulfate, 2,2′-azobisisobutyronitrile, 2 , 2'-azobis (2-methylbutyronitrile), 2,2 ' -Azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobisisobutyrate, various redox catalysts and the like are suitable.

  The amount of polymerization initiator used is (meth) acrylic acid alkyl ester (a1) and carboxyl group-containing unsaturated monomer (a2), and if necessary, other unsaturated monomer (a3) monomer. The amount is preferably 0.03 to 5 parts by weight, more preferably 0.05 to 3 parts by weight with respect to 100 parts by weight of the mixture. If the amount is too small, the polymerization rate tends to be slow. Tend to.

  The polymerization initiator may be added in advance to the polymerization can, may be added immediately before the start of polymerization, or may be added during the polymerization as necessary. Moreover, you may add to the monomer mixture of (a1)-(a3) previously, or may add to the emulsion liquid which consists of this monomer mixture. In addition, the polymerization initiator may be separately dissolved in a solvent or the above monomer and added, or the dissolved polymerization initiator may be further added in an emulsified form.

Further, if necessary, a pH buffer may be used at the time of polymerization to adjust the pH at the time of polymerization. The amount of the pH buffer used is the monomer mixture 100 of (a1) to (a3). It is preferable that it is 0.01-10 weight part with respect to a weight part, especially 0.1-3 weight part.
The pH buffering agent is not particularly limited as long as it has a pH buffering action. Specifically, sodium bicarbonate, potassium bicarbonate, monosodium phosphate, monopotassium phosphate, disodium phosphate, phosphorus Examples thereof include trisodium acid, sodium acetate, ammonium acetate, sodium formate, and ammonium formate.

  The amount of water used is a monomer mixture 100 of (meth) acrylic acid alkyl ester (a1) and carboxyl group-containing unsaturated monomer (a2), and if necessary, other unsaturated monomer (a3). It is preferable that it is 25-200 weight part with respect to a weight part, More preferably, it is 30-150 weight part, Especially preferably, it is 35-120 weight part. If the amount of water used is too small, the resulting resin composition will have a high viscosity, and the polymerization stability will tend to decrease. If too much water is used, the concentration of the resulting resin composition will be low, resulting in drying when forming a film. Tend to decrease.

In the presence of an emulsifier, the polymerization initiator is prepared by mixing a monomer mixture of the (meth) acrylic acid alkyl ester (a1), the carboxyl group-containing unsaturated monomer (a2), and the other unsaturated monomer (a3). As a method for the polymerization,
(1) After water is charged in a reaction can and heated, an emulsion obtained by mixing and emulsifying water, an emulsifier and a monomer mixture in advance is dropped or divided to polymerize.
(2) After charging water to the reaction can and raising the temperature, a part of the emulsion prepared by mixing and emulsifying water, emulsifier and monomer mixture in advance is charged and polymerized, and the remaining emulsion is added dropwise or dividedly. To continue the polymerization.
(3) Water, an emulsifier, and the like are charged into a reaction can and the temperature is raised, and then an emulsion obtained by mixing and emulsifying water, an emulsifier, and a monomer mixture in advance is added dropwise or divided and polymerized.
Etc.

As the polymerization conditions in the above polymerization method, for example, in the methods (1) and (3), a temperature range of usually about 40 to 90 ° C. is appropriate, and the dropwise addition or divided addition is performed in about 1 to 8 hours. Thereafter, aging is carried out at the same temperature for about 1 to 5 hours.
In the method (2), 1 to 50% by weight of the monomer mixture is polymerized at 40 to 90 ° C. for 0.1 to 1 hour, and then the remaining monomer mixture is dropped or divided over about 1 to 8 hours. After that, it is aged for about 1 to 5 hours at the same temperature.

In the above polymerization method, the monomer mixture may be used by dissolving an emulsifier (or a part of the emulsifier) in the monomer mixture. However, as described above, the state of the O / W type emulsion is previously determined. Is preferable from the viewpoint of polymerization stability.
As a method for preparing the emulsion, for example, the (meth) acrylic acid alkyl ester (a1) and the carboxyl group-containing unsaturated monomer (a2) after dissolving the emulsifier in water, and other unsaturated as required Examples thereof include a method of charging the monomer (a3) and stirring and emulsifying this mixed solution, or a method of charging the above (a1) to (a3) with stirring after dissolving the emulsifier in water.

Agitation at the time of emulsification of the emulsion can be carried out using a stirring device in which the components are mixed and a stirring blade such as a homodisper or paddle blade is attached.
There is no problem as long as the temperature during emulsification is such that the mixture does not react during emulsification, and usually about 5 to 60 ° C. is appropriate.

  Thus, an acrylic emulsion [I] is obtained. In the present invention, the acrylic emulsion [I] preferably has a gel fraction of 40 to 90% by weight, more preferably 45 to 85% by weight, especially 50%. ~ 80 wt% is preferred. If the gel fraction is too small, there is a large amount of adhesive residue and the stain resistance tends to decrease, and the increase in adhesive strength over time tends to increase. On the other hand, if it is too large, the adhesive force tends to be small or the adhesion to the substrate tends to be reduced.

  Examples of a method for adjusting the gel fraction of the acrylic emulsion [I] to 40 to 90% by weight include, for example, a method of adjusting the blending of a chain transfer agent, a blending amount of an emulsifier and a polymerization initiator, Saturated monomers (monomers having at least two unsaturated groups in the molecule) and unsaturated monomers having self-crosslinkable functional groups (hydrolyzable silyl group-containing monomers and methylol group-containing monomers) And the like, and a method of copolymerizing unsaturated monomers having functional groups capable of reacting with each other.

  The gel fraction of the acrylic emulsion [I] is the ratio of the solvent-insoluble component of the resin composition. In the 10 μm coating film of the acrylic emulsion [I] dried at 40 ° C. for 24 hours. It is determined as a ratio (%) of the remaining coating film weight after immersion to the coating film weight before immersion when dipped in toluene at 23 ° C. for 24 hours and dried.

The average particle size of the obtained acrylic emulsion [I] is 2 μm or less, particularly 1 μm or less, and it is possible to adjust the high concentration and low viscosity required for high-speed coating. It is preferable in a certain point. The lower limit of the average particle diameter is usually 0.01 μm, preferably 0.1 μm.
Furthermore, the resin content concentration of the acrylic emulsion [I] is preferably 40 to 68% by weight, and particularly preferably 50 to 65% by weight from the viewpoint of drying property and coating property.

  Thus, in the present invention, acrylic emulsion [I] is obtained, but in the present invention, a cross-linking agent may be used to adjust the cohesive force as necessary. Examples of the crosslinking agent include oxazoline compounds, carbodiimide compounds, metal compounds, epoxy compounds, aziridine compounds, isocyanate compounds, melamine compounds, hydrazine compounds, and amine compounds.

  Further, if necessary, a tackifier (for example, rosin-based, rosin ester-based, polyterpene resin, chroman-indene resin, petroleum-based resin, terpene phenol-based resin, etc.) can be blended. As a method of blending such a tackifier, for example, a method of blending an emulsion-type tackifier during or after emulsion polymerization, or dissolving a solid-type tackifier in an unsaturated monomer mixture, The method of mix | blending by emulsion polymerization is mentioned. Other plasticizers (eg liquid polybutene, mineral oil, lanolin, liquid polyisoprene and liquid polyacrylate), antiseptic / antifungal agents, rust preventives, freeze-thaw stabilizers, plasticizers, high boiling point solvents, pigments, colorants, Add fillers (zinc white, titanium white, calcium carbonate, clay, etc.), metal powders, antifoaming agents, wetting agents, thickeners, adhesion control agents, etc. as appropriate, or before polymerization of the above emulsion polymerization It can also be added during polymerization.

Thus, the peelable water-based pressure-sensitive adhesive composition of the present invention is obtained. Such a peelable water-based pressure-sensitive adhesive composition is usually applied to a substrate sheet and dried to form a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet or pressure-sensitive adhesive tape. In order to produce such pressure-sensitive adhesive sheets and pressure-sensitive adhesive members such as pressure-sensitive adhesive tapes, first, the peelable water-based pressure-sensitive adhesive composition of the present invention is used as it is or at an appropriate concentration. Adjust and apply to the treated surface of the base material that has been subjected to silicon treatment or the like, or apply directly to the base material and dry by, for example, heat treatment at 80 to 105 ° C. for 5 seconds to 10 minutes. An agent layer can be formed.
Alternatively, the release-type aqueous pressure-sensitive adhesive composition can be applied to a release film and dried, and then transferred onto a substrate.

Examples of the base material include, but are not limited to, paper, synthetic paper, plastic film, metal foil, and the like. Examples of the paper and synthetic paper base material include high-quality paper, cast-coated paper, and coating. Examples include paper materials such as paper, neutral paper, art paper, synthetic paper mainly made of polypropylene, and thermal paper. In the present invention, particularly when neutral paper or glossy paper containing calcium carbonate is used, a remarkable effect is exhibited. Examples of the plastic film substrate include polyvinyl chloride, polybutene, polybutadiene, polyurethane, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polyethylene, polypyropylene, ethylene-propylene copolymer, polymethylpentene, polybutylene terephthalate. Etc. In addition, a porous material such as a nonwoven fabric can be used as the base material for the double-sided tape.
The thickness of the substrate is usually 10 to 300 μm, particularly preferably 20 to 100 μm. On one or both sides of the substrate, a layer made of the above-described peelable aqueous pressure-sensitive adhesive composition is 1 to 100 μm, and more preferably 3 to 3 μm. It is provided in a thickness of 50 μm, particularly 5 to 30 μm, and is in the form of a sheet or tape.

The peelable water-based pressure-sensitive adhesive composition of the present invention is for temporary surface protection or temporary adhesion for preventing scratches or contamination during transport, processing, cutting, etc. of metal plates, glass plates, plastic plates, etc. It is used as a pressure-sensitive adhesive tape or sheet pressure-sensitive adhesive.
For example, it has sufficient adhesive force when protecting the surface of the adherend, and after the processing such as transportation, processing, cutting, etc., the adhesive member such as an adhesive sheet or adhesive tape is removed from the adherend. It can be easily peeled off.

  Thus, the peelable pressure-sensitive adhesive composition of the present invention comprises an acrylic resin [A], an emulsifier comprising an anionic reactive emulsifier (b1) and an anionic nonreactive emulsifier (b2) that do not contain an alkylene oxide chain in the structure. Since the acrylic emulsion [I] containing is used, it shows an excellent anti-contamination effect such that there is little contamination such as adhesive residue and sticking marks on the adherend during peeling.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “%” and “part” mean weight basis unless otherwise specified.

[Production of acrylic emulsion [I]]
2-ethylhexyl acrylate (a1) 99.0 parts, acrylic acid (a2) 1.0 part, anionic reactive emulsifier (b1) (manufactured by Sanyo Chemical Co., Ltd., “Eleminol JS-20”, active ingredient concentration 39% by weight, In general formula (1), R ₁ = C ₁₃ H ₂₇ , R ₂ = H, X = SO ₃ Na, Y = 1) 2.1 parts (active ingredient 0.8 parts), anionic non-reactive emulsifier (b2 ) (Manufactured by Kao Corporation, “Perex SS-L”, active ingredient concentration 50% by weight, R ₁ = alkyl group, R ₂ = H, X ₁ = X ₂ = SO ₃ Na in the general formula (2)) 2.4 Parts (active ingredient 1.2 parts) and water 36.2 parts were mixed and stirred to obtain an emulsion composed of a monomer mixture.
Next, 47.0 parts of water was added to a flask equipped with a condenser and a stirring blade, dissolved by stirring, heated to 75 ° C., and then added with 1.0 part of an aqueous 10% ammonium persulfate solution. After a minute, 1.4 parts of the above emulsion and 10% ammonium persulfate aqueous solution were added dropwise, and the whole amount was added dropwise over 4 hours to carry out emulsion polymerization. After completion of dropping, stirring was continued for 3.5 hours while maintaining the temperature at 70 ° C., followed by cooling to room temperature, adding 3 parts of 5% aqueous ammonia solution, neutralizing acid groups, and filtering through a 150 mesh nylon mesh. An acrylic emulsion [I] was obtained (average particle size 570 nm, solid content 53.5%, viscosity 25.7 mPa · s).

The average particle size of the obtained acrylic emulsion [I] was measured using a particle size distribution measuring device (NICOMP ^™ 380).

[Manufacture of adhesive sheet]
The acrylic emulsion [I] obtained above was applied on a polyethylene terephthalate (PET) film having a thickness of 25 μm with an applicator so that the thickness of the coating film after drying was 20 μm. After drying for 5 minutes, it was laminated on a commercially available silicone release paper with a laminating roll at a pressure of 25 N / cm ² to obtain an adhesive sheet.
The following evaluation was performed about the obtained adhesive sheet.

(Peelability after time)
The pressure-sensitive adhesive sheet was adhered to a melamine coated plate (white) manufactured by Nippon Test Panel Co., Ltd. by reciprocating two 2 kg rollers at 23 ° C. and 50% RH, and then changed with time (i) (23 ° C., 50% After leaving for 20 minutes at RH), and with respect to change over time (ii) (after leaving for 1 hour at 100 ° C.), the surface of the adherend after peeling the adhesive sheet by hand was visually observed to evaluate the adhesive residue.
◎ ... No contamination was observed. ○ ・ ・ ・ Lead residue of 0 to less than 10% was observed. △ ... Less than 10 to 50% of paste residue was observed. Adhesive residue was observed

Example 2
In Example 1, 6.4 parts of the anionic reactive emulsifier “Eleminol JS-20” (2.5 parts of active ingredient) and 2.0 parts of the anionic non-reactive emulsifier “Perex SS-L” (active ingredient) Except for changing to 1.0 part), the same procedure as in Example 1 was carried out to obtain an acrylic emulsion [I]. Further, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 and evaluated.

Example 3
In Example 1, an anionic non-reactive emulsifier was changed from “Perex SS-L” to “Neopelex G-25” having a structure shown below (made by Kao Corporation, active ingredient concentration: 25%, chemical name: sodium dodecylbenzenesulfonate) ) Except for changing to 4.8 parts (1.2 parts active ingredient), the same procedure as in Example 1 was carried out to obtain an acrylic emulsion [I]. went.

Comparative Example 1
Example 1 An acrylic emulsion [I] was obtained in the same manner as in Example 1 except that 5.13 parts of the anionic reactive emulsifier “Eleminol JS-20” (2.0 parts of active ingredient) was used alone. Further, a pressure-sensitive adhesive sheet was produced and evaluated in the same manner as in Example 1.

（ＡＯ＝アルキレンオキサイド）
Comparative Example 2
In Example 1, an anionic non-reactive emulsifier was changed from “Perex SS-L” to “New Coal 240” having the structure shown below (manufactured by Nippon Emulsifier Co., Ltd., active ingredient concentration 30% by weight, chemical name: polyoxyalkylene glycol. (Sulfuric acid ester / Na salt) Except for changing to 4.0 parts (1.2 parts of active ingredient), the same procedure as in Example 1 was performed to obtain an acrylic emulsion [I]. Manufactured and evaluated.

(AO = alkylene oxide)

〔上記一般式において、Ｒ_１＝Ｃ_１０Ｈ_２１であり、Ｘ＝ＳＯ_３ＮＨ_４であり、ｎ＝２〜２０である。〕
Comparative Example 3
In Example 1, 2.0 parts of an anionic reactive emulsifier alone from “Eleminol JS-20” to “Aqualon KH-10” (Daiichi Kogyo Seiyaku Co., Ltd., active ingredient concentration: 100% by weight) having the structure shown below. Changed and performed in the same manner as in Example 1 except that the anionic non-reactive emulsifier (b2) was not used to obtain an acrylic emulsion [I]. Further, an adhesive sheet was produced in the same manner as in Example 1 and evaluated. Went.

[In the above general formula, R ₁ = C ₁₀ H ₂₁ , X = SO ₃ NH ₄ , and n = 2-20. ]

注）
表中の数値は配合量（部）を示す。
・ＪＳ−２０：エレミノールＪＳ−２０（三洋化成社製）
・ＳＳ−Ｌ：ペレックスＳＳ−Ｌ（花王社製）
・Ｇ−２５：ネオペレックスＧ−２５（花王社製）
・ＫＨ−１０：アクアロンＫＨ−１０（第一工業製薬社製）
・Ｎ−２４０：ニューコール２４０（日本乳化剤社製）
・経時変化（ｉ）：２３℃、５０％ＲＨで２０分間放置した後の評価
・経時変化（ｉｉ）：１００℃で１時間放置した後の評価 Comparative Example 4
In Example 1, except for changing to 0.8 part of an anionic reactive emulsifier “AQUALON KH-10” and 2.4 parts of an anionic non-reactive emulsifier “PEREX SS-L” (1.2 parts of active ingredient). It carried out similarly to Example 1 and obtained acrylic emulsion [I], and also manufactured the adhesive sheet similarly to Example 1, and evaluated it.

Table 1 shows the evaluation results of Examples and Comparative Examples.

note)
The numerical value in a table | surface shows a compounding quantity (part).
・ JS-20: Eleminor JS-20 (manufactured by Sanyo Chemical Industries)
・ SS-L: Perex SS-L (manufactured by Kao Corporation)
・ G-25: Neo-Perex G-25 (manufactured by Kao)
・ KH-10: Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd.)
N-240: New Coal 240 (manufactured by Nippon Emulsifier Co., Ltd.)
Change over time (i): Evaluation after leaving for 20 minutes at 23 ° C. and 50% RH Change over time (ii): Evaluation after leaving for 1 hour at 100 ° C.

  From the above results, since Comparative Examples 1 to 4 do not use the emulsifiers (b1) and (b2), the increase in the adhesive strength over time under heat and humidity conditions is large and the peelability is poor. On the other hand, since Examples 1-3 used the emulsifiers (b1) and (b2) in combination, an adhesive member having little change over time and excellent in stain resistance was obtained. It turns out that it is useful as an adhesive composition.

  The peelable pressure-sensitive adhesive composition of the present invention has little change with time in pressure-sensitive adhesive properties and is excellent in peelability, and thus is useful for applications such as surface protective films, paint masking tapes, pressure-sensitive adhesive seals, and pressure-sensitive adhesive labels.

Claims (6)

A peelable aqueous pressure-sensitive adhesive composition comprising an acrylic emulsion [I] containing an acrylic resin [A] and an emulsifier [B],
An acrylic resin [A] is obtained by emulsion polymerization of a monomer mixture in the presence of an emulsifier [B],
The emulsifier [B] contains an anionic reactive emulsifier (b1) containing no alkylene oxide chain and an anionic non-reactive emulsifier (b2) containing no alkylene oxide chain ,
An anionic reactive emulsifier (b1) containing no alkylene oxide chain is an emulsifier represented by the following general formula (1):
The anionic non-reactive emulsifier (b2) not containing an alkylene oxide chain is selected from emulsifiers represented by the following general formula (2), alkyl sulfate esters, alkylbenzene sulfonates, alkyl sulfosuccinates, and alkyl diphenyl ether disulfonates. A release-type water-based pressure-sensitive adhesive composition, characterized by being at least one of the above .

[In General Formula (1), R ₁ and R ₂ are hydrogen or an alkyl group, and may be the same or different. X is a metal salt of SO ₃ NH ₄ or SO ₃ , and Y is an alkylene group. ]

[In General Formula (2), R ₁ and R ₂ are hydrogen or an alkyl group, and X ₁ and X ₂ are SO ₃ NH ₄ or a metal salt of SO ₃ . R ₁ , R ₂ and X ₁ , X ₂ may be the same or different from each other.
] Anionic non-reactive emulsifier (b2) is releasable aqueous pressure-sensitive adhesive composition according to claim 1 Symbol mounting, characterized in that an emulsifier represented by the general formula (2). The acrylic resin [A] is characterized in that a (meth) acrylic acid alkyl ester (a1) containing an alkyl group having 4 to 12 carbon atoms and a carboxyl group-containing unsaturated monomer (a2) are used as a copolymerization component. The peelable water-based pressure-sensitive adhesive composition according to claim 1 or 2 . The peelable pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the acrylic resin [A] is dispersed and stabilized by an emulsifier [B]. A peelable water-based pressure-sensitive adhesive comprising the peelable pressure-sensitive adhesive composition according to any one of claims 1 to 4 . A peelable pressure-sensitive adhesive member, wherein the peelable aqueous pressure-sensitive adhesive according to claim 5 is laminated on at least one surface of a substrate.