JP6898970B2 - Water-based adhesive - Google Patents

Description

The present invention relates to a water-based pressure-sensitive adhesive that exhibits sufficient adhesive strength to paper or an olefin base material. More specifically, the present invention relates to a water-based pressure-sensitive adhesive (adhesive) used for product labels and tag labels.

Adhesive products such as labels, adhesive tapes, adhesive films, and adhesive sheets usually consist of an adhesive and a substrate. Adhesives are used to make paper products such as tapes, sheets and labels, and to label containers such as PET bottles and metals.

As described above, adhesives have been used in various adhesive products, but water-based adhesives that do not use organic solvents are attracting attention due to growing concern about global environmental problems and human safety. The water-based pressure-sensitive adhesive needs to have excellent adhesive strength to various base materials such as paper, olefin base material and metal.

As one of the means for improving the adhesive force to the base material, there is a method of blending an aqueous resin having a low glass transition temperature as one component of the water-based pressure-sensitive adhesive. When the glass transition temperature of the water-based resin is low, the adhesive strength of the water-based adhesive is improved, but it becomes difficult to cut an adhesive product such as an adhesive label or perform so-called secondary processing such as slit processing. When the adhesive product is secondarily processed with a cutter or the like, if the adhesive strength of the adhesive is too high, the adhesive will adhere to the cutter or the like. Therefore, there is a demand for a water-based pressure-sensitive adhesive that has excellent adhesive strength to a base material and does not adversely affect the processing of a pressure-sensitive adhesive product.

In Patent Document 1 and Patent Document 2, an aqueous resin having a low glass transition temperature is used as a main component, and a small amount of an aqueous resin having a high glass transition temperature is blended to prepare an aqueous pressure-sensitive adhesive.

The aqueous pressure-sensitive adhesive of Patent Document 1 contains an aqueous dispersion (A) having a glass transition temperature of 90 to 105 ° C. and an aqueous dispersion (B) having a glass transition temperature of −75 to −45 ° C. The component (A) and the component (B) are blended in the ratio of (A) / (B) = 1/99 to 5/85 (solid content conversion) ([Claim 1]).

The pressure-sensitive adhesive of Patent Document 2 is an acrylic copolymer (A) with a glass transition temperature of −40 ° C. or lower by 85 to 95 parts by weight, and an acrylic copolymer (B) with a glass transition temperature of 30 ° C. or higher by 5 to 15 parts by weight. It has a part by weight ([claim 1]).

Since the water-based pressure-sensitive adhesives in both documents contain a resin having a high glass transition temperature, the processability of the pressure-sensitive adhesive product is improved, but the tack (adhesive strength) is reduced by that amount. Further, the water-based pressure-sensitive adhesive is required to have not only adhesive strength but also performance (holding power) of holding a label or tape on a paper base material or a metal base material for a long period of time. Further, considering that a label or a sheet can be attached to a curved surface or a base material having a complicated shape, the adhesive is required to have excellent curved surface adhesiveness.

Japanese Unexamined Patent Publication No. 2006-016517 Japanese Unexamined Patent Publication No. 2009-263494

The present invention has been made to solve the above problems, and is an aqueous pressure-sensitive adhesive having excellent adhesive strength, facilitating secondary processing of a pressure-sensitive adhesive product, and excellent holding power to a base material of the pressure-sensitive adhesive product and curved surface adhesiveness. The purpose is to provide.

As a result of diligent studies to solve the above problems, the present inventor mixed a plurality of types of aqueous resin emulsions having different glass transition temperatures when preparing an aqueous pressure-sensitive adhesive, and weight-averaged one aqueous resin emulsion. It has been found that when the molecular weight is a specific value, the adhesive strength, holding power, curved surface adhesiveness, and secondary processability of the water-based pressure-sensitive adhesive are improved, and the present invention has been completed.

That is, the present invention and preferred embodiments of the present invention are as follows.

1. 1. (A) Aqueous resin emulsion containing a polymer having a glass transition temperature of −65 to −40 ° C., and (B) An aqueous resin containing a polymer having a glass transition temperature of 60 to 120 ° C. and having a weight average molecular weight of 300,000 or more. An aqueous pressure-sensitive adhesive containing an emulsion.

2. (B) The water-based pressure-sensitive adhesive according to 1 above, wherein the aqueous resin emulsion has a weight average molecular weight of 300,000 to 1,200,000.

3. 3. (B) The water-based pressure-sensitive adhesive according to 1 or 2 above, wherein the aqueous resin emulsion has a weight average molecular weight of 300,000 to 1,000,000.

4. (A) 100 parts by weight (solid content conversion value) of the aqueous resin emulsion, (B) 10 to 30 parts by weight (solid content conversion value) of the aqueous resin emulsion is blended, according to any one of 1 to 3 above. Water-based adhesive.

5. (B) The water-based pressure-sensitive adhesive according to any one of 1 to 4 above, wherein the aqueous resin emulsion contains a polymer of a monomer containing (meth) acrylic acid and / or a (meth) acrylic acid derivative.

6. The above 1 to 1 to which a tackifier resin containing 10 parts by weight (solid content equivalent value) or less is blended with respect to 100 parts by weight (solid content equivalent value) of the total weight of the (A) aqueous resin emulsion and (B) water-based resin emulsion The water-based adhesive according to any one of 5.

7. The water-based pressure-sensitive adhesive according to 6 above, wherein the pressure-sensitive adhesive resin contains a rosin ester-based pressure-sensitive adhesive resin.

8. An adhesive product obtained by using the water-based adhesive according to any one of 1 to 7 above.

9. An aqueous resin emulsion which is a raw material for producing an aqueous pressure-sensitive adhesive, contains a polymer having a glass transition temperature of 60 to 120 ° C., and has a weight average molecular weight of 300,000 or more.

10. 9. The aqueous resin emulsion according to 9 above, which has a weight average molecular weight of 300,000 to 1,200,000.

11. 9. The aqueous resin emulsion according to 9 above, which has a weight average molecular weight of 300,000 to 1,000,000.

The water-based pressure-sensitive adhesive of the present invention has excellent adhesive strength, facilitates secondary processing of the pressure-sensitive adhesive product using the water-based pressure-sensitive adhesive, and has excellent holding power to the base material of the pressure-sensitive adhesive product and curved surface adhesiveness.

Further, the adhesive product obtained by the water-based adhesive of the present invention can hold a label or a sheet on the base material even if the base material has a curved structure or a complicated shape, and even when it is cut by a cutter or the like, it is a cutter. Adhesive does not adhere to.

The water-based pressure-sensitive adhesive according to the present invention has (A) an aqueous resin emulsion (sometimes referred to as component (A)) containing a polymer having a glass transition temperature of −65 to −40 ° C., and (B) a glass transition temperature. It contains a polymer at 60 to 120 ° C. and contains an aqueous resin emulsion (sometimes referred to as component (B)) having a weight average molecular weight of 300,000 or more.

In the present specification, the "aqueous resin emulsion" is a dispersion liquid containing both polymer fine particles as a dispersoid and an aqueous medium as a dispersion medium. The polymer fine particles are dispersed in an aqueous medium to form an emulsion (milky lotion, emulsion).

As used herein, the term "aqueous medium" refers to general water such as tap water, distilled water, or ion-exchanged water, which is a water-soluble or dispersible organic solvent and is an emulsion according to the present invention. It may contain an organic solvent having poor reactivity with the raw material (for example, monomer, etc.) of.

The component (A) and the component (B) used in the present invention may further contain water-soluble or water-dispersible monomers, oligomers, prepolymers and / or resins, and water-based resins as described below. Alternatively, it may contain an emulsifier, a polymerizable emulsifier, a polymerization reaction initiator, a chain extender and / or various additives usually used in producing a water-soluble resin.

(A) Aqueous Resin Emulsion In the present invention, the (A) Aqueous Resin Emulsion contains a polymer having a glass transition temperature of −65 to −40 ° C. The glass transition temperature of the polymer contained in the component (A) is preferably −60 to −45 ° C., particularly preferably −60 to −50 ° C. When the glass transition temperature of the polymer contained in the (A) aqueous resin emulsion is within the above range, the water-based pressure-sensitive adhesive of the present invention has excellent adhesive strength.

In the present specification, the glass transition temperature of the polymer contained in the (A) aqueous resin emulsion is the glass transition temperature of the homopolymer obtained when the monomer as the raw material of the polymer is homopolymerized (hereinafter, “Tg of homopolymer”). It is also calculated from). The mixing ratio (part by weight) of each monomer is determined in consideration of the Tg of this homopolymer. Specifically, the Tg of the polymer contained in the (A) aqueous resin emulsion can be obtained by calculating using the formula (1).

1 / Tg = C ₁ / Tg ₁ + C ₂ / Tg ₂ + ... + C _n / Tg _n (1)
[In the calculation formula (1), Tg is the theoretical Tg, C _n of the copolymer, the weight ratio of n-th monomer n is included in the monomer mixture, Tg _n is the n-th monomer Tg and n of the homopolymer of the body n are the number of monomers constituting the copolymer, and are positive integers. ]

As the Tg of the monomeric homopolymer, the value described in the literature can be used. As such a document, for example, there is "POLYMER HANDBOOK" (4th edition; published by John Wiley & Sons, Inc.). As an example, the monomeric homopolymer Tg described in POLYMER HANDBOOK is shown below.

Methyl methacrylate (hereinafter referred to as "MMA", Tg = 105 ° C)
N-Butyl acrylate (hereinafter referred to as "n-BA", Tg = -54 ° C)
2-Ethylhexyl acrylate (hereinafter referred to as "2EHA", Tg = -70 ° C)
Styrene (hereinafter referred to as "St", Tg = 100 ° C.)
Acrylic acid (hereinafter referred to as "AA", Tg = 106 ° C)
Methacrylic acid (hereinafter referred to as "MAA", Tg = 130 ° C.)
N-Butyl methacrylate (hereinafter referred to as "BMA", Tg = 20 ° C.)
In the present invention, not only the above-mentioned monomer but also the glass transition temperature of homopolymers of other monomers can be applied to the formula (1).

Further, in the present invention, the solid content concentration of the aqueous resin emulsion (A) is not particularly limited, but is preferably 5 to 70% by weight in the component (A). The solid content of the emulsion refers to the solid content obtained by drying the emulsion at 105 ° C. for 3 hours.

Examples of the aqueous resin emulsion include an acrylic resin emulsion, a vinyl acetate resin emulsion, a vinyl chloride-vinyl acetate copolymer emulsion, a styrene-butadiene copolymer emulsion, an ethylene-vinyl acetate copolymer emulsion, and a polyester. Examples thereof include resin-based emulsions, urethane resin-based emulsions, nylon resin-based emulsions, and polyolefin-based emulsions.

In the present invention, the aqueous resin emulsion (A) is preferably an acrylic resin emulsion containing an acrylic resin as a dispersoid. Hereinafter, an acrylic resin emulsion will be described as an example of the (A) aqueous resin emulsion, but the present invention is not limited thereto. In the present specification, acrylic acid and methacrylic acid are collectively referred to as "(meth) acrylic acid", and acrylic acid derivatives and methacrylic acid derivatives are also collectively referred to as "(meth) acrylic acid derivatives".

The (meth) acrylic acid or (meth) acrylic acid derivative is a compound having one or more (meth) acryloyl groups, and may have two or more (meth) acryloyl groups.

In the present invention, the (A) aqueous resin emulsion contains (meth) acrylic acid and / or (meth) acrylic acid derivative represented by the following formula (I) as a compound having one or more (meth) acryloyl groups. It preferably contains a polymer of monomers.

CH ₂ = C (R ¹ ) -COOR ² (I)
(In formula (I), R ¹ is a hydrogen atom or a methyl group, and R ² is a hydrogen atom or a functional group other than a hydrogen atom.)

^{When R 2} is a hydrogen atom in the above formula (I), the compound represented by the formula (I) is (meth) acrylic acid, and when R ² is a functional group other than a hydrogen atom, the formula (I) is It becomes a (meth) acrylic acid derivative.

In the formula (I), R ² is not particularly limited, but is preferably a hydrogen atom or an alkyl group. Considering the component (B) described later, it is more preferable that the aqueous resin emulsion (A) contains a polymer of a monomer containing ^{(meth) acrylic acid (that is, R 2 is a hydrogen atom).}

In the formula (I), when R ² is an alkyl group, the alkyl group may be chain-like or cyclic, and may be linear or branched-chain. In the case of a chain alkyl group, the number of carbon atoms is preferably 1 to 20, more preferably 1 to 16. In the case of a cyclic alkyl group, the number of carbon atoms is preferably 3 to 8, and more preferably 3 to 6.

In the formula (I), when R ² is a chain alkyl group, the R ² is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, or a 2-ethylhexyl. Examples thereof include a group, a heptyl group, an octyl group, a nonyl group, an isononyl group, a decyl group, a lauryl group, a myristyl group and a cetyl group. When R ² is a cyclic alkyl group ^{, examples of R 2} include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and the like.

As the "(meth) acrylic acid derivative", a (meth) acrylic acid alkyl ester is preferable. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate. , (Meta) hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, ( Examples thereof include isononyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate, and cetyl (meth) acrylate. Of these, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate are more preferable.

Further, as another "(meth) acrylic acid derivative" that can be used in the present invention, it has an OH group (meth) such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. ) Acrylic acid ester; (meth) acrylic such as polyethylene glycol mono (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polypropylene glycol mono (meth) acrylate, and acetoacetoxyethyl (meth) acrylate. Diesters and monoesters obtained from acids and glycols; (meth) acrylic acid amides such as (meth) acrylic acid amide, N-methylol acrylamide, and diacetone acrylamide; glycidyl methacrylate, and 3,4-epoxycyclohexyl (meth). ) A (meth) acrylic acid ester having an epoxy group such as acrylate can be exemplified. These (meth) acrylic acid and (meth) acrylic acid derivatives may be used alone or in combination of two or more.

Further, in the production of the (A) aqueous resin emulsion, the (meth) acrylic acid and / or the (meth) acrylic acid derivative can be used alone or in combination of two or more other copolymerizable monomers. .. In this case, the weight of the (meth) acrylic acid and the (meth) acrylic acid derivative (if both are included, the total weight) is added to the total weight of the monomer used for producing the polymer contained in the (A) aqueous resin emulsion. , 80% by weight or more (including 100% by weight) is preferable.

Such "other copolymerizable monomers" include, for example, a carboxyl group having an ethylenic double bond such as crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and maleic anhydride. Or a monomer containing an acid anhydride; a monomer having an ethylenic double bond such as vinyl chloride and acrylonitrile and containing a chlorine or a cyano group; vinyl acetate, vinyl propionate, t-butyl vinyl ester, and Carboxylic acid vinyl ester such as vinyl versatic acid; Aromatic vinyl monomer such as styrene; Vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tripropoxysilane, vinyl triisopropoxysilane, vinylmethyldiethoxysilane, vinylmethyldi Propoxysilane, vinyltris (β-methoxyethoxy) silane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltripropoxysilane, γ-methacryloxypropylmethyl Examples thereof include a monomer having an ethylenic double bond and containing silicon, such as dimethoxysilane and γ-methacryloxypropyltris (isopropoxy) silane.

In the present invention, as the "other copolymerizable monomer", a monomer having an ethylenic double bond and containing silicon is preferable, and in particular, γ-methacryloxypropyltrimethoxysilane and γ-methacryloxy. Propylmethyldimethoxysilane is preferred.

In the present invention, the polymer contained in the component (A) may be a crosslinked polymer in which a monomer is crosslinked, or may be a non-crosslinked polymer.

In the present invention, examples of the polymer (A) having a glass transition temperature of −65 to −40 ° C. contained in the aqueous resin emulsion include acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate. A polymer of a polymerizable monomer containing at least one selected from the group consisting of a monomer having a methyl acrylate and an ethylenic double bond and containing silicon is preferable, and a polymer containing two or more of these is preferable. A polymer of a polymer is more preferable, and a copolymer of a mixture of polymerizable monomers containing all of them is further preferable.

In the present invention, as a method for producing (A) an aqueous resin emulsion, for example, refer to an ordinary emulsion polymerization method (Souichi Muroi, Chemistry of Polymer Latex, pp. 51-54, Published by Polymer Publishing Association 1970). ) And the forced emulsion method (see Japanese Patent Publication No. 6-102748) and the like can be exemplified. Further, as the (A) aqueous resin emulsion, a commercially available one can also be used.

The (A) aqueous resin emulsion according to the present invention is known using, for example, the above-mentioned (meth) acrylic acid and / or (meth) acrylic acid derivative, and if necessary, other copolymerizable monomers. It can be obtained by the emulsion polymerization method of. "Emulsion polymerization" is radical polymerization carried out in an aqueous medium using an emulsifier. The emulsion (A) according to the present invention can be obtained according to a known procedure of an emulsion polymerization method.

As a procedure of emulsion polymerization, for example, when emulsifying and polymerizing (meth) acrylic acid and / or (meth) acrylic acid derivative,
(I) A method in which (meth) acrylic acid and / or a (meth) acrylic acid derivative and an emulsifier are charged in an aqueous medium and polymerized.
(Ii) A method of continuously or intermittently dropping (meth) acrylic acid and / or a (meth) acrylic acid derivative and an emulsifier into an aqueous medium for polymerization.
(Iii) A method in which (meth) acrylic acid and / or a (meth) acrylic acid derivative and an emulsifier are added to water to prepare an emulsion, which is continuously or intermittently dropped into an aqueous medium for polymerization. Etc. can be exemplified.

The "emulsifier" has a monomer emulsifying power, forms micelles in the process of emulsion polymerization to provide a place for polymerization to the monomer, and is immobilized on the surface of the polymer particles during or after the polymerization to stabilize the dispersion of the particles. Aim. Examples of the emulsifier include anionic surfactants, nonionic surfactants, polymer surfactants, and "reactive surfactants" having a radically polymerizable double bond in one molecule of the emulsifier.

As an "anionic surfactant", for example
Alkali metal alkyl sulfates such as sodium dodecyl sulfate and potassium dodecyl sulfate;
Sodium dodecyl polyglycol ether sulfate;
Ammonium alkyl sulfates such as ammonium dodecyl sulfate;
Sodium sulfosinoate;
Alkali metal salts of sulfonated paraffins, alkyl sulfonates such as ammonium salts of sulfonated paraffins;
Fatty acid salts such as sodium laurate, triethanolamine oleate, triethanolamine avietate;
Alkylaryl sulfonates such as sodium dodecylbenzene sulfonate, alkali metal sulfate of alkaline phenol hydroxyethylene;
High alkylnaphthalene sulfonate;
Naphthalene sulfonic acid formalin condensate;
Dialkyl sulfosuccinate;
Polyoxyethylene alkyl sulfate salt;
Polyoxyethylene alkylaryl sulfate salt;
Etc. can be exemplified.

As a "nonionic surfactant", for example
Polyoxyethylene alkyl ether;
Polyoxyethylene alkylaryl ether;
Sorbitan fatty acid ester;
Polyoxyethylene sorbitan fatty acid ester;
Fatty acid monoglyceride such as monolaurate of glycerol;
Polyoxyethylene oxypropylene copolymer;
Condensation product of ethylene oxide with aliphatic amines, amides or acids;
Etc. can be exemplified.

Examples of the "polymer surfactant" include polyvinyl alcohol and the like.

Examples of the "reactive surfactant" include sulfate ester salts of polyoxyethylene allylglycidyl nonylphenyl ether (Adecaria Soap SE series (trade name), manufactured by Asahi Denka Kogyo Co., Ltd.), α-sulfo-ω- (1-). (Aalkoxy) Methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl) ammonium salt (Adecaria soap SR series (trade name), manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyethylene (Or alkylene) alkyl (or alkenyl) ether ammonium sulfate (PD series (trade name), manufactured by Kao), sulfosuccinic acid type surfactant (latemul 180 series (trade name), manufactured by Kao), alkylallyl sulfosuccinic acid Sodium salt (eleminol JS-20 (trade name), manufactured by Sanyo Kasei Kogyo Co., Ltd.), polyoxyethylene nonylpropenylphenyl ether sulfate ammonium salt (Aquaron HS series (trade name), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene -1- (Allyloxymethyl) alkyl ether sulfate ammonium salt (Aqualon KH series (trade name), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene allylglycidyl nonylphenyl ether (Adecaria soap NE series (trade name)), Asahi Denka Kogyo Co., Ltd.), Polyoxyethylene nonylpropenyl ether (Aqualon RN series (trade name), Daiichi Kogyo Seiyaku Co., Ltd.), α-hydro-ω- (1- (alkoxy) methyl-2- (propenyloxy) Examples thereof include ethoxy) -poly (oxy-1,2-ethaneziyl) (Adecaria soap ER series (trade name), manufactured by Asahi Denka Kogyo Co., Ltd.).

Further, a chain transfer agent can be used to adjust the molecular weight of the acrylic resin obtained by radical polymerization. Examples of the "chain transfer agent" include mercaptoethanol, thioglycerol, thioglycolic acid, octyl thioglycolate, methyl mercaptopropionate, n-dodecyl mercaptan and the like.

In the present invention, the solid content concentration of the aqueous resin emulsion (A) is not particularly limited, but is preferably 5 to 70% by weight based on the component (A). The solid content of the emulsion refers to the solid content obtained by drying the emulsion at 105 ° C. for 3 hours.

(B) Aqueous Resin Emulsion In the present invention, the (B) Aqueous Resin Emulsion (Component (B)) is a polymer having a glass transition temperature of 60 to 120 ° C. and a weight average molecular weight of 300,000 or more. ..

The glass transition temperature of the polymer contained in the (B) aqueous resin emulsion is 60 to 120 ° C, preferably 65 to 120 ° C, and particularly preferably 80 to 120 ° C. (B) When the glass transition temperature of the polymer in the aqueous resin emulsion is 60 ° C. or higher, the water-based pressure-sensitive adhesive of the present invention can impart excellent processability to the pressure-sensitive adhesive product. The method for calculating the glass transition temperature is the same as that for the glass transition temperature of the component (A).

(B) The weight average molecular weight (Mw) of the aqueous resin emulsion is 300,000 or more, preferably 300,000 to 1,200,000, most preferably 300,000 to 1,000,000. When the Mw of the component (B) is 300,000 or more, the water-based pressure-sensitive adhesive of the present invention can further improve the adhesive strength and holding power of the pressure-sensitive adhesive product. In the present invention, the weight average molecular weight (Mw) of the aqueous resin emulsion means the weight average molecular weight of the solid content of the aqueous resin emulsion.

In the present specification, Mw means a weight average molecular weight (Mw) measured by a gel permeation chromatography (GPC) apparatus and converted into a monodisperse molecular weight polystyrene.

Specifically, HLC-8220 (manufactured by Tosoh Corporation) was used as the GPC apparatus, and TSKgel SUPERMULTIPORE HZ-M × 2 (manufactured by Tosoh Corporation) was used as the GPC column, and the sample was dissolved in tetrahydrofuran (THF) to concentrate. A 0.5 wt% sample solution is prepared, 20 μL of this sample solution is injected into the column at a flow velocity of 0.35 ml / min, and the weight average molecular weight (Mw) is measured. The column temperature is 40 ° C. and the UV of the detector is 254 nm.

As with the component (A), the component (B) preferably contains a polymer of a monomer containing a (meth) acrylic acid and / or a (meth) acrylic acid derivative. The component (B) may contain "another copolymerizable monomer" as in the component (A). However, the monomer used as the raw material for the component (A) and the monomer used as the raw material for the component (B) do not have to be the same.

In the present invention, as an embodiment of the polymer (B) contained in the aqueous resin emulsion having a glass transition temperature of 60 to 120 ° C., the polymer comprises styrene, methacrylate, n-butyl methacrylate, 2-ethylhexyl acrylate and methyl methacrylate. It is preferably a polymer of a polymerizable monomer containing one or more kinds selected from the group, and more preferably a copolymer of a mixture of polymerizable monomers containing two or more of these. A copolymer of a mixture containing all polymerizable monomers is more preferred.

The method for producing the (B) aqueous resin emulsion may be the same as the method for producing the (A) aqueous resin emulsion. However, the aqueous resin emulsion (B) may be obtained by polymerizing a polymerizable monomer to prepare a prepolymer and further polymerizing the prepolymer.

In the water-based pressure-sensitive adhesive of the present invention, the amount of the (B) aqueous resin emulsion is preferably 10 parts by weight or more in terms of solid content with respect to 100 parts by weight (solid content conversion value) of (A) aqueous resin emulsion. , 20 parts by weight or more, more preferably 40 parts by weight or less, more preferably 30 parts by weight or less, still more preferably 25 parts by weight or less.

When the compounding ratio of both the component (A) and the component (B) is within the above range, the water-based pressure-sensitive adhesive of the present invention has a better balance of adhesive strength, holding power, and curved surface adhesiveness. It is possible to provide an adhesive product with excellent secondary processing (slit processing) properties.

The blending of the component (A) and the component (B) is usually not limited as long as it is a method of blending an emulsion and a method capable of obtaining the water-based pressure-sensitive adhesive according to the present invention.

As a preferred embodiment of the aqueous pressure-sensitive adhesive of the present invention, the component (A) has acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate and an ethylenic double bond and silicon. It is an aqueous resin emulsion containing a polymer obtained by polymerizing a monomer containing one or more selected from the group consisting of monomers containing styrene, and the component (B) is styrene, methacrylic acid, n-butyl methacrylate. , 2-Ethylhexyl acrylate and methyl methacrylate are preferably aqueous resin emulsions containing a polymer obtained by polymerizing a monomer containing at least one selected from the group.

As a more preferable embodiment of the water-based pressure-sensitive adhesive of the present invention,
(A) Obtained by copolymerizing a mixture containing acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate and a monomer having an ethylenic double bond and containing silicon. An aqueous resin emulsion containing the polymer to be obtained, and (B) an aqueous resin emulsion containing a polymer obtained by copolymerizing a mixture containing styrene, methacrylate, n-butyl methacrylate, 2-ethylhexyl acrylate and methyl methacrylate. It is preferably contained.

The water-based adhesive has an excellent overall balance of adhesive strength, holding power and curved surface adhesiveness, and improves the processability of the adhesive product.

The water-based pressure-sensitive adhesive of the present invention preferably further contains a tack-imparting resin. Examples of the "adhesive-imparting resin" include rosin-based resin, terpene resin, terpene / phenol-based resin, kumaron-inden resin, petroleum-based hydrocarbon resin, and the like. Examples of the rosin-based resin include rosin esters and rosin phenols.

The tackifier resin may be commercially available, for example, Super Ester E-730-55, Super Ester E-720, Super Ester 786-60, Super Ester E-650, Super Ester E-865, Tamanol E-200. , Tamanor E-100, AM-1002 (manufactured by Arakawa Chemical Co., Ltd.); 822E and the like can be exemplified. Both names are indicated by product names.

Further, in recent years, due to increasing environmental awareness, it is preferable to use a toluene / xylene-free type tackifier resin and a solvent-free type tackifier resin. Examples of such tackifier resins include Super Ester E-865NT, Super Ester E-625NT, Super Ester NS-100H, Super Ester NS-121, Tamanol E-200NT (manufactured by Arakawa Chemical Co., Ltd.); Harrier SK-218NS. , Harrier SK-323NS, Harrier SK-370N, Harrier SK-501NS, Harrier SK-385NS and the like can be exemplified. Both names are indicated by product names.

In the present invention, the tackifier resin is blended in an amount of 10 parts by weight (solid content conversion value) or less with respect to 100 parts by weight (solid content conversion value) of the total weight of the component (A) and the component (B). It is preferably 8 parts by weight or less, and most preferably 4 to 7 parts by weight. By reducing the amount of the tackifier resin added, the water-based pressure-sensitive adhesive of the present invention does not reduce its adhesive strength to an olefin base material or the like, maintains its holding power, and further improves the processability of the pressure-sensitive adhesive product using the adhesive. ..

The water-based pressure-sensitive adhesive of the present invention may appropriately contain a plasticizer, a defoaming agent, a thickener, a wax, a preservative, a colorant, a filler and the like as additional additives. These additives may be mixed after mixing the component (A) and the component (B), or may be mixed in advance with either the component (A) or the component (B).

Examples of the "plasticizer" include glycerin; polyhydric alcohols such as ethylene glycol and propylene glycol; polyesters such as adipic acid, benzoic acid, acetylcitrate, alkylsulfonic acid, and phthalic acid; sucrose. , Sugars such as sorbitol; organic solvents such as cellosolves and the like can be exemplified.

As a "foamer", for example
Silicone-based defoamers such as dimethylpolysiloxane, polyoxyalkylene-modified silicone, organic-modified polysiloxane, and fluorosilicone;
Oil-based defoamers such as castor oil, sesame oil, linseed oil, and animal and vegetable oils;
Fatty acid defoamers such as stearic acid, oleic acid, palmitic acid;
Isoamylstearic acid, diglycollauric acid, distearylsuccinic acid, distearic acid, sorbitan monolauric acid, glycerin fatty acid ester, polyoxyethylene sorbitan, monolauric acid butyl stearate, sucrose fatty acid ester, ethylacetic acid alkyl ester of sulfonated lithinol acid , Natural wax and other fatty acid ester-based defoaming agents;
Alcohol-based antifoaming agents such as polyoxyalkylene glycol and its derivatives, polyoxyalkylene alcohol hydrate, diamilphenoxyethanol, 3-heptanol, and 2-ethylhexanol;
Ether-based antifoaming agents such as 3-heptyl cellsolve and nonyl cellsolve-3-heptyl carbitol;
Phosphate-based defoamers such as tributyl phosphate, sodium octyl phosphate, tris (butoxyethyl) phosphate;
Amine-based defoamers such as diamilamine;
Amide antifoaming agents such as polyalkylene amide, acylate polyamine, dioctadecanoyl piperidine;
Metal soap defoamers such as aluminum stearate, calcium stearate, potassium oleate, calcium salt of wool olein;
Sulfonic acid ester defoamers such as sodium lauryl sulfonate and sodium dodecyl sulfonate;
Hydrophobic silica-based defoaming agents; mineral oil-based defoaming agents and the like can be exemplified.

As a "thickener", for example
Gelatin, casein, alginic acid, propylene glycol alginate, triethanolamine alginate, ammonium alginate, sodium alginate, guar gum, gellan gum, xanthan gum, welan gum, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, etc. Natural polymer thickener;
Polyvinyl-based thickeners such as polyvinyl alcohol, polyvinylpyrrolidone, and polyvinylbenzyl ether copolymers;
Sodium polyacrylate, acrylate- (meth) acrylate copolymer, sodium polymethacrylate, methacrylic acid- (meth) acrylate copolymer, modified polyacrylic acid sulfonate, modified polymethacrylate sulfonic acid Poly such as salt, styrene-acrylic acid copolymer, styrene-acrylic acid- (meth) acrylic acid ester copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid- (meth) acrylic acid ester copolymer, etc. (Meta) Acrylic acid-based thickener;
Polyether-based thickeners such as pluronic polyether, polyether dialkyl ester, polyether urethane modified product, polyether dialkyl ether, and polyether epoxy modified product;
Itaconic acid-based thickeners such as polyitaconic acid, itaconic acid- (meth) acrylic acid ester copolymer, itaconic acid-maleic acid copolymer, itaconic acid-acrylic acid copolymer, itaconic acid-methacrylic acid copolymer, etc. ;
Maleic anhydride-maleic anhydride- (meth) acrylic acid ester copolymer, maleic anhydride-acrylonitrile copolymer, maleic anhydride-vinyl acetate copolymer, partial ester of vinyl methyl ether-maleic anhydride copolymer, etc. Acid-based thickener;
Examples of higher fatty acid amide-based thickeners can be used.

The filler refers to a substance added for the purpose of improving performance, reducing costs, etc., and is not particularly limited as long as it is usually used as a filler. Specifically, calcium carbonate, magnesium carbonate, silica, talc, clay, alumina and the like can be exemplified.

When producing the water-based pressure-sensitive adhesive of the present invention, it is preferable to mix the component (A) and the component (B), and if necessary, mix the above additives. "Mixing" is a method usually used for mixing a resin composition, and is not particularly limited as long as it is a method capable of obtaining the water-based pressure-sensitive adhesive according to the present invention.

The aqueous pressure-sensitive adhesive according to the present invention obtained as described above preferably has a viscosity (30 ° C., solid content concentration of 55% by weight) of 2000 to 5000 mPa · s as measured by a B-type rotary viscometer. It is more preferably 2000 to 4500 mPa · s, and particularly preferably 2000 to 4000 mPa · s. The water-based pressure-sensitive adhesive of the present invention has a viscosity in the above range, which makes it easy to apply when manufacturing a pressure-sensitive adhesive product.

The water-based pressure-sensitive adhesive of the present invention has both components of (A) water-based resin emulsion and (B) water-based resin emulsion, and in some cases, by containing the above-mentioned additives, it is excellent in adhesive strength, holding power, and curved surface adhesiveness. , It is possible to improve the secondary processability of the adhesive product.

The pressure-sensitive adhesive product according to the present invention is a product having the above-mentioned water-based pressure-sensitive adhesive, and the adherend may be attached to the base material via the above-mentioned water-based pressure-sensitive adhesive, or may be on the adherend. Alternatively, it may be a product before being attached to the base material or the adherend with the water-based adhesive on the base material. The pressure-sensitive adhesive product according to the present invention may be one in which an adherend is attached to a base material via the above-mentioned water-based pressure-sensitive adhesive. The coating of the water-based adhesive may be a base material or an adherend. Examples of the material of the adherend include paper and plastic. The shape of the adherend includes a sheet, a film, a label, and the like. As the base material, paper, plastic, metal, glass, non-woven fabric and the like are used.

The adhesive product of the present invention is a so-called adhesive tape, adhesive sheet, adhesive film, or adhesive label. Specifically, it protects the electronics fields such as backgrinding tapes for semiconductor wafers, dicing tapes, protective tapes for transporting electronic parts, protective tapes for printed substrates, window glass protective films, baking finish films, and automobiles to users. Guard film for display, marking film for display, marking film for decoration, automobile field such as sponge tape for cushioning / protection / heat insulation / soundproofing, medical / sanitary material field such as adhesive plaster and percutaneous absorption patch, for electrical insulation, Adhesive films and protective films for identification, duct construction, window glass protection, curing, packaging, packing, office work, household use, fixing, bundling, repair, etc. can be mentioned.

The method for producing the adhesive product is not particularly limited. A water-based adhesive may be applied to the base material or adherend of the adhesive product by a usual method, and the two may be bonded together.

Specifically, the water-based adhesive of the present invention is coated on a paper or plastic film base material or a peelable sheet by various coating devices such as a comma coater, a reverse coater, a slot die coater, a lip coater, a gravure chamber coater, and a curtain coater. By applying it on top and drying it, various adhesive products such as adhesive sheets and adhesive labels can be obtained.

The coating amount of the water-based adhesive is preferably from 5 to 100 g / ^{m 2} as a solid content, more preferably from 5 to 50 g / ^{m 2,} particularly preferably from 10 to 20 g / ^{m 2.} Here, the solid content of the water-based pressure-sensitive adhesive refers to the solid content obtained by drying the water-based pressure-sensitive adhesive at 105 ° C. for 3 hours.

The following embodiments are also preferable in the present invention.

(Appendix 1) The glass transition temperature is −65 to −40 ° C., and includes one or more selected from the group consisting of acrylic acid, n-butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate and methyl methacrylate. The first resin on which the polymerizable monomer is polymerized,
A polymerizable monomer having a glass transition temperature of 60 to 120 ° C. and containing at least one selected from the group consisting of styrene, methacrylic acid, n-butyl methacrylate, 2-ethylhexyl acrylate and methyl methacrylate was polymerized. A water-based adhesive containing a second resin.

(Appendix 2) Further, the water-based pressure-sensitive adhesive according to Appendix 1, which contains 10 parts by weight or less of a tackifier resin based on the total weight of the first resin and the second resin.

The tackifier resin is preferably contained in an amount of 10 parts by weight or less, more than 0 parts by weight, and 10 parts by weight or less based on the total weight of the first resin and the second resin. preferable.

(Appendix 3) The water system according to Appendix 1 or 2 above, wherein at least one of the first resin and the second resin has an ethylenic double bond and a structural unit based on a silicon-containing monomer. Adhesive.

(Supplementary Note 4) The water-based pressure-sensitive adhesive according to any one of Supplementary notes 1 to 3, wherein the weight average molecular weight of the second resin is 300,000 or more.

(Appendix 5) An aqueous resin emulsion which is a raw material for producing an aqueous pressure-sensitive adhesive, contains a polymer having a glass transition temperature of 60 to 120 ° C., and has a weight average molecular weight of 300,000 or more.

(Appendix 6) The aqueous resin emulsion according to Appendix 5, wherein the weight average molecular weight is 300,000 to 1,200,000.

(Appendix 7) The aqueous resin emulsion according to Appendix 5, wherein the weight average molecular weight is 300,000 to 1,000,000.

Hereinafter, examples of the present invention will be described in detail, but these examples are merely one aspect of the present invention, and the present invention is not limited to these examples.

The water-based pressure-sensitive adhesive according to the present invention was prepared from (A) an aqueous resin emulsion (component (A)) and (B) an aqueous resin emulsion (component (B)). The polymerizable monomers used as raw materials for the components (A) and (B) and each additive are described below. In addition, in Table 1 to Table 4, the numerical value which shows the amount of each compounding component is the number of parts by weight converted by the solid content.

The polymerizable monomers used as the raw materials for the component (A) and the component (B) are shown below. The Tg of the homopolymer of the polymerizable monomer is a value calculated by the above-mentioned theoretical calculation formula.

<Polymerizable monomer>
Styrene (hereinafter referred to as "St") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 100 ° C)
Methyl methacrylate (hereinafter referred to as "MMA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 105 ° C)
Acrylonitrile (hereinafter referred to as "AN") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 105 ° C)
N-Butyl methacrylate (hereinafter referred to as "n-BMA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 20 ° C.)
Methyl acrylate (hereinafter referred to as "MA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 8 ° C)
Isobonyl methacrylate (hereinafter referred to as "IBX") (manufactured by Kyoeisha Chemical Co., Ltd., Tg = 180 ° C.)
Acrylic acid (hereinafter referred to as "AA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 106 ° C)
Methacrylic acid (hereinafter referred to as "MAA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = 130 ° C)
N-Butyl acrylate (hereinafter referred to as "n-BA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = -54 ° C)
2-Ethylhexyl acrylate (hereinafter referred to as "2EHA") (manufactured by Wako Pure Chemical Industries, Ltd., Tg = -70 ° C)
SZ-6030 (3-methacryloxypropyltrimethoxysilane)

<Production example of (A) aqueous resin emulsion>
(A1) Synthesis of Aqueous Resin Emulsion As shown in Table 1, 86 parts by weight of 2EHA, 12.7 parts by weight of MA, and 1.3 parts by weight of AA were uniformly mixed to prepare a monomer solution. A monomer solution is added to a solution in which 18.8 parts by weight of water and 1.0 part by weight of Aqualon KH10 (trade name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. are uniformly mixed, and these mixed solutions are mixed using a stirrer. Stirred to prepare a pre-emulsion.

A reactor equipped with a stirrer, a condenser and a thermometer was charged with 42 parts by weight of water and 0.14 parts by weight of Aqualon KH10, the inside of the system was replaced with nitrogen gas, and then the charged liquid was heated to 80 ° C. Then, 2 parts by weight of a 3% by weight ammonium persulfate (hereinafter, also referred to as “APS”) aqueous solution was added to the charging liquid.

After another 10 minutes, 8 parts by weight of the above-mentioned preemulsion and 8 parts by weight of a 3% aqueous solution of APS, which is a polymerization catalyst, were simultaneously added dropwise over 3 hours while maintaining the temperature inside the reactor at 80 ° C. The temperature inside the reactor was maintained at 80 ° C., and 1 hour after the completion of the dropping, 2.4 parts by weight of a 3% aqueous solution of APS was added to the reactor, and stirring was continued for another 2 hours to obtain an aqueous resin emulsion (A1). .. The obtained aqueous resin emulsion (A1) was adjusted to pH 8.0 with aqueous ammonia.

The aqueous resin emulsion (A1) had a glass transition temperature of −61 ° C. and a solid content concentration of 58% by weight. The solid content is the weight percentage of the portion that remains after drying in an oven at 105 ° C. for 3 hours with respect to the weight before drying.

Synthesis of (A2) to (A'5) The synthesis of the aqueous resin emulsions (A2) to (A'5) is the same as that of (A1) except that the raw material monomer is used as shown in Table 1. It was synthesized by the method of. Table 1 shows the composition of the polymerizable monomer when synthesizing (A2) to (A'5).

<(B) Production example of aqueous resin emulsion>
(B1) Synthesis of Aqueous Resin Emulsion As shown in Table 2, St95.0 parts by weight, MMA 4.5 parts by weight, and AA 0.5 parts by weight were uniformly mixed to prepare a monomer solution.

A solution in which 18.8 parts by weight of water, 6.0 parts by weight of Kao's Latemul E-150 (trade name), and 0.7 parts by weight of Kao's Perex OT-P (trade name) are uniformly mixed. Then, a monomer solution was added, and these mixed solutions were stirred using a stirrer to prepare a pre-emulsion.

A reactor equipped with a stirrer, a condenser and a thermometer was charged with 65.0 parts by weight of water and 0.6 parts by weight of Latemul E-150, the inside of the system was replaced with nitrogen gas, and then the charged liquid was brought to 75 ° C. It was heated.

3.8 parts by weight of the pre-emulsion was added to the preparation liquid, and after 10 minutes, 1.6 parts by weight of a 2.0% by weight ammonium persulfate (hereinafter, also referred to as “APS”) aqueous solution was added.

After another 20 minutes, 6.6 parts by weight of the remaining preemulsion and 6.6 parts by weight of a 2.0% aqueous solution of APS as a polymerization catalyst were simultaneously added dropwise over 3 hours while maintaining the temperature inside the reactor at 75 ° C. The temperature inside the reactor was maintained at 75 ° C., and 1 hour after the completion of the dropping, 2.2 parts by weight of a 3% aqueous solution of APS was added to the reactor, and stirring was continued for another 2 hours to obtain an aqueous resin emulsion (B1). .. The obtained aqueous resin emulsion (B1) was adjusted to pH 8.0 with aqueous ammonia.

The aqueous resin emulsion (B1) had a glass transition temperature of 100 ° C., a solid content concentration of 50% by weight, and a weight average molecular weight of Mw551000. The solid content is the weight percentage of the portion that remains after drying in an oven at 105 ° C. for 3 hours with respect to the weight before drying.

The weight average molecular weight was calculated by converting the solid content of the aqueous resin emulsion obtained above into polystyrene using the following apparatus.
Equipment: Tosoh Corporation HLC-8220GPC, Column: Tosoh Corporation TSKgel SUPERMULTIPORE HZ-M x 2, Flow rate: 0.35 ml / min, Injection volume: 20 μL, Column temperature: 40 ° C, Eluent: THF, Injection sample Concentration: 0.5% by mass, Detector: UV254nm

(B2) Synthesis of Aqueous Resin Emulsion As shown in Table 2, St99.5 parts by weight and 0.5 parts by weight of AA were uniformly mixed to prepare a monomer solution.

A solution in which 18.8 parts by weight of water, 6.0 parts by weight of Kao's Latemul E-150 (trade name), and 0.7 parts by weight of Kao's Perex OT-P (trade name) are uniformly mixed. Then, a monomer solution was added, and these mixed solutions were stirred using a stirrer to prepare a pre-emulsion.

A reactor equipped with a stirrer, a condenser and a thermometer was charged with 52.0 parts by weight of water and 0.6 parts by weight of Latemul E-150, the inside of the system was replaced with nitrogen gas, and then the charged liquid was brought to 70 ° C. It was heated.

3.8 parts by weight of the pre-emulsion was added to the preparation liquid, and after 10 minutes, 2.4 parts by weight and 0.8 parts by weight of a 1.0% by weight aqueous solution of ammonium persulfate (hereinafter, also referred to as "APS") were added. 2.4 parts by weight of an aqueous sodium sulfite solution was added.

After another 20 minutes, while maintaining the temperature inside the reactor at 70 ° C., 5.7 parts by weight of the remaining 1.0% aqueous solution of APS and the 0.8% by weight aqueous sodium sulfite solution of APS, which is a polymerization catalyst, were maintained. 5.6 parts by weight were added dropwise simultaneously over 3 hours. The temperature inside the reactor was maintained at 70 ° C., and 1 hour after the completion of the dropping, 3.1 parts by weight of a 3.2% by weight aqueous solution of APS and 3.1 parts by weight of a 2.6% by weight aqueous solution of sodium disulfide were added to the reactor. Was added to (B2), and stirring was continued for 3 hours to obtain an aqueous resin emulsion. The obtained aqueous resin emulsion (B2) was adjusted to pH 8.0 with aqueous ammonia.

The aqueous resin emulsion (B2) had a glass transition temperature of 100 ° C., a solid content concentration of 50% by weight, and a weight average molecular weight of Mw864000.

(B3) Synthesis of Aqueous Resin Emulsion As shown in Table 2, a monomer solution was prepared by uniformly mixing 88.5 parts by weight of MMA, 8.5 parts by weight of 2EHA, and 3.0 parts by weight of MAA. A monomer solution is added to a solution in which 30.6 parts by weight of water and 1.9 parts by weight of Aqualon KH10 (trade name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. are uniformly mixed, and these mixed solutions are mixed using a stirrer. A pre-emulsion was prepared with stirring. A reactor equipped with a stirrer, a condenser and a thermometer was charged with 60.0 parts by weight of water and 0.2 parts by weight of Aqualon KH10, the inside of the system was replaced with nitrogen gas, and then the charged liquid was heated to 80 ° C. .. Then, 6.6 parts by weight of the pre-emulsion was added to the preparation liquid, and after 10 minutes, 2.4 parts by weight of a 1.2% by weight aqueous solution of sodium persulfate (hereinafter, also referred to as "SPS") was added. After a further 20 minutes, 5.7 parts by weight of the remaining preemulsion and 5.7 parts by weight of a 1.2% aqueous solution of SPS as a polymerization catalyst were added dropwise simultaneously over 3 hours. The temperature inside the reactor was kept at 80 ° C., and 1 hour after the completion of the dropping, 2.2 parts by weight of a 3% aqueous solution of SPS was added to the reactor, and stirring was continued for another 2 hours to obtain an aqueous resin emulsion (B3). .. The obtained aqueous resin emulsion (B3) was adjusted to pH 8.0 with aqueous ammonia.

The aqueous resin emulsion (B3) had a glass transition temperature of 80 ° C., a solid content concentration of 50% by weight, and a weight average molecular weight of Mw324000.

Synthesis of (B4) to (B'6) The synthesis of (B4) to (B'6) aqueous resin emulsion is the same as that of (B2) except that the raw material monomer is used as shown in Table 2. It was synthesized by the method of.

Synthesis of (B'7) to (B'8) Regarding the synthesis of (B'7) to (B'8) aqueous resin emulsions, except that n-dodecyl mercaptan (hereinafter, also referred to as "NDM") was added to the monomer solution. Was synthesized in the same manner as in (B2).

<Preparation of water-based adhesive>
Preparation of water-based pressure-sensitive adhesives of Examples 1 to 8 and Comparative Examples 1 to 9 (A) Aqueous resin (B) Aqueous resin as shown in Tables 3 and 4 with respect to 100 parts by weight (in terms of solid content) of the aqueous resin emulsion. An emulsion and a tackifier (manufactured by Arakawa Chemical Industry Co., Ltd., Super Ester E730-55 (trade name)) were blended to prepare an aqueous pressure-sensitive adhesive . In this specification, "Example 7" and "Example 8" shall be read as "Reference Example 7" and "Reference Example 8", respectively.

<Preparation of evaluation sample>
The water-based adhesive was coated on the release paper with a table coater so that the coating amount after drying was 20 g / m ^2. After drying in a dryer for 3 minutes in an atmosphere of 105 ° C., high-quality paper was attached to a release paper to prepare a label-type evaluation sample. Using this evaluation sample, the adhesive strength, holding power, curved surface adhesiveness, and slit property were evaluated. The evaluation methods and evaluation criteria are shown below.

<Adhesive strength>
A stainless steel plate (30 mm × 100 mm × 15 mm) whose surface has been polished in advance and a polypropylene plate (30 mm × 100 mm × 15 mm) whose surface has been degreased with isopropyl alcohol are allowed to stand at 23 ° C. and 5 ° C. for 1 hour or more, respectively. The above-mentioned evaluation sample was attached, and the adhesive strength of the water-based adhesive was evaluated.

The evaluation sample was cut into strips having a width of 25 mm, the release paper was peeled off, and then the sample was attached to a stainless steel plate and a polypropylene plate. Thirty minutes after the application, a low-speed strain type universal testing machine (manufactured by JT Toshi Co., Ltd.) was used to peel off in the 180 ° direction at a peeling speed of 300 mm / min, and the strength at the time of peeling was measured. The evaluation criteria are shown below.

⊚: The peel strength was 15 N / 25 mm or more, and the paper substrate of the evaluation sample was broken.
◯: The peeling strength was 15 N / 25 mm or more, and the peeling was performed at the interface between the plate and the water-based adhesive.
Δ: The peel strength was less than 15 N / 25 mm, and the peel was peeled off at the interface between the plate and the water-based adhesive.
X: Zipping, transfer of the water-based pressure-sensitive adhesive layer to the plate, and partial cohesive failure of the water-based pressure-sensitive adhesive layer occurred.

<Holding power>
An evaluation sample is attached to a stainless steel plate whose surface has been polished in advance, and crimped with a roll so that a pressure of 2 kg is applied to a pasted area of 25 mm × 25 mm, and this crimped material is crimped under the conditions of a temperature of 60 ° C. and 50 RH%. It was allowed to stand for 1 hour. By lowering a weight of 1 kg vertically below the adhesive surface, applying a load of 1 kg and leaving it under the condition of 60 ° C., and measuring the time (minutes) until the weight falls, the water-based adhesive can be used. The holding power was evaluated. The evaluation criteria are shown below.

◎: After 1440 minutes, the weight does not fall and there is no deviation from the bonding position. ○: After 1440 minutes, the weight does not fall and there is a deviation from the bonding position. △: Weight falls in 720 minutes or more and less than 1440 minutes. Yes ×: Weight falls in less than 720 minutes

<Curved surface adhesiveness>
Under the condition of 23 ° C., a polypropylene round bar having a diameter of 8 mm and a length of 150 mm and an evaluation sample were allowed to stand, and the evaluation sample was cut into a width of 20 mm and a length of 15 mm. The release paper was peeled off from the evaluation sample and attached to a polypropylene round bar. The release paper was strongly pressed with a finger, crimped onto a round bar, and allowed to stand at 23 ° C. for 24 hours. Graph paper was sandwiched between both ends of the crimped material, and the length of floating and peeling was measured. Three samples were measured, and the curved surface adhesiveness was evaluated by the average value of the calculated values.

⊚: Peeling is less than 0.5 mm ○: Peeling is 0.5 mm or more and less than 1.0 mm Δ: Peeling is 1.0 mm or more and less than 2.0 mm ×: Peeling is 2.0 mm or more

<Slit property>
The evaluation sample and a commercially available hand slitter were allowed to stand for 1 hour or more under the condition of 23 ° C. The weight of the slit blade was measured in advance, the evaluation sample was cut to a length of 300 mm with this slit blade, the weight of the slit blade was remeasured, and the weight change before and after cutting was defined as the amount of water-based adhesive adhering.

⊚: Adhesive amount of water-based adhesive is less than 0.5 mg ○: Adhesive amount of water-based adhesive is 0.5 mg or more and less than 1.0 mg Δ: Adhesive amount of water-based adhesive is 1.0 mg or more and less than 2.0 mg × : Adhesive amount of water-based adhesive is 2.0 mg or more

As shown in Table 3, since the water-based pressure-sensitive adhesive of the examples contains both the component (A) and the component (B), it is excellent in adhesive strength, holding power, curved surface adhesiveness and slit property, and is comprehensive. Excellent balance. In particular, the water-based pressure-sensitive adhesives of Examples 3 to 6 have the above-mentioned performance significantly improved by having the component (A2).

As shown in Table 4, the water-based pressure-sensitive adhesive of the comparative example does not contain any of the component (A) and the component (B), and therefore has any of adhesive strength, holding power, curved surface adhesiveness, and slitting property. Is marked with a cross.

The present invention can provide a water-based pressure-sensitive adhesive. The water-based adhesive according to the present invention is applied to paper, plastic, metal, or the like to obtain an adhesive product called an adhesive tape, an adhesive sheet, or an adhesive label.

Claims (3)

(A) An aqueous resin emulsion containing a polymer having a glass transition temperature of −65 to −45 ° C., and (B) a polymer containing a glass transition temperature of 65 to 100 ° C. and a weight average molecular weight of 300,000 to 1,200, Contains an aqueous resin emulsion of 000
A water-based pressure-sensitive adhesive in which 20 to 30 parts by weight (solid content conversion value) of component (B) is blended with respect to 100 parts by weight (solid content conversion value) of component (A). The water-based pressure-sensitive adhesive according to claim 1, further containing a tack-imparting resin. An adhesive product obtained by using the water-based adhesive according to claim 1 or 2.