JP2006241419A - Removable aqueous adhesive composition and decoration sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-pack type removable aqueous adhesive composition having excellent adhesive power, holding power, and peel strength under constant load, hardly increasing the adhesive power with time, hardly leaving the adhesive paste and stain after removal, and hardly changing adhesive properties with time; and to provide a decoration sheet using the adhesive composition. <P>SOLUTION: The removable aqueous adhesive composition contains [A] an emulsion comprising the following acrylic resin and having <70 wt% gel fraction, [B] a hydrazine-based compound and [C] a phosphoric acid-based compound. The acrylic resin is obtained by subjecting a monomer mixture comprising (a1) 50-99.89 wt% alkyl ester of (meth)acrylic acid containing 4-12C alkyl group, (a2) 0.1-10 wt% carboxy group-containing unsaturated monomer, (a3) 0.01-10 wt% carbonyl group-containing unsaturated monomer and (a4) 0-49.89 wt% other unsaturated monomers to an emulsion polymerization in the presence of an anion-type reactive emulsifier, and has >-50°C and ≤-25°C glass transition temperature. The decoration sheet is obtained by using the composition as an adhesive layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a one-pack type that is excellent in adhesive force, holding force, constant load peeling force, has little change in adhesive force over time, has no adhesive residue after re-peeling, no contamination, and has little change in adhesive performance over time. The present invention relates to a re-peelable water-based pressure-sensitive adhesive composition and a decorative sheet using the same.

  Conventionally, re-peelable pressure-sensitive adhesive compositions have been widely used for applications such as pressure-sensitive adhesive tapes, pressure-sensitive adhesive sheets, pressure-sensitive adhesive labels, and surface protective films.

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 re-peelable pressure-sensitive adhesive composition. For example, improvement of re-peelability and contamination resistance during re-peeling A) 50 to 99.9% by weight of an acrylate monomer having an alkyl group having 2 to 14 carbon atoms, b) 0.1 to 5% by weight of a carboxyl group-containing monomer, and c ) A water-soluble crosslinking agent containing an oxazoline group is added to a water-dispersed copolymer of a monomer mixture composed of 0 to 49.9% by weight of a monomer copolymerizable with the components a and b. It is blended so that the oxazoline group is 0.1 to 5 equivalents per equivalent of carboxyl group contained in the coalescence, the solvent-soluble content is 40% by weight or less, and the elastic modulus is ² to 50 kg / cm ² . Re-peeling with a re-peeling force of 500 g / 20 mm width or less Type pressure-sensitive adhesive (see, for example, Patent Document 1), a) 50 to 99.9% by weight of an acrylate monomer having an alkyl group having 2 to 14 carbon atoms, b) a carboxyl group-containing monomer 0 1) to 5% by weight, and c) a carbodiimide group is added to a water-dispersed acrylate copolymer of a monomer mixture comprising 0 to 49.9% by weight of a monomer copolymerizable with the above components a and b. The crosslinking agent to be contained is blended so that the ratio of the carbodiimide group to the carboxyl group of the copolymer (carbodiimide group / carboxyl group) is 0.1 to 5.0, and the removability is 500 g / 20 mm width. The following water dispersion type pressure sensitive adhesive for re-peeling (for example, refer patent document 2) is proposed.

  However, in the disclosed technologies of Patent Documents 1 and 2, regarding removability, Patent Document 1 has a time of about 20 minutes at 23 ° C. after pasting, and Patent Document 2 also has a time of 24 hours at 23 ° C. and 65% RH after pasting. The re-peelability of the aging level was not satisfactory to the recent required performance. Therefore, the re-peelable pressure-sensitive adhesive composition is required to have re-peelability over a longer time.

Japanese Patent Laid-Open No. 10-114887 JP 2001-131512 A

  The present invention is a one-pack type that is excellent in adhesive force, holding force, constant load peeling force, has little change in adhesive force over time, has no adhesive residue after re-peeling, no contamination, and has little change in adhesive performance over time. An object of the present invention is to provide a re-peelable water-based pressure-sensitive adhesive composition and a decorative sheet using the same.

  The present invention relates to (meth) acrylic acid alkyl ester (a1) 50 to 99.89% by weight containing an alkyl group having 4 to 12 carbon atoms, carboxyl group-containing unsaturated monomer (a2) 0.1 to 10% by weight. %, Carbonyl group-containing unsaturated monomer (a3) 0.01 to 10% by weight, and other unsaturated monomer (a4) 0 to 49.89% by weight, Emulsion [A] obtained by emulsion polymerization in the presence of a hydrophilic emulsifier and having a glass fraction of -50 ° C. and lower than −25 ° C. and having a gel fraction of less than 70% by weight, hydrazine compound [ B], and a re-peelable water-based pressure-sensitive adhesive composition containing the phosphate ester compound [C].

  The anionic reactive emulsifier is preferably a compound neutralized with a monovalent metal salt.

  The anionic reactive emulsifier is preferably a compound that does not contain an ethylene oxide chain in the structure.

  (Meth) acrylic acid alkyl ester (a1), carboxyl group-containing unsaturated monomer (a2) in which the hydrazide group in hydrazine-based compound [B] contains an alkyl group having 4 to 12 carbon atoms in emulsion [A] ), Carbonyl group-containing unsaturated monomer (a3), and 0.001 to 1.0 equivalent per carbonyl group equivalent contained in the acrylic resin composed of the other unsaturated monomer (a4). Is preferred.

  The content of the phosphate ester compound [C] is preferably 0.01 to 5.0 parts by weight with respect to 100 parts by weight of the solid content of the emulsion [A].

  The re-peelable water-based pressure-sensitive adhesive composition preferably further contains a wetting agent [D].

  The present invention also relates to a decorative sheet having a pressure-sensitive adhesive layer formed from the re-peelable water-based pressure-sensitive adhesive composition.

  The re-peelable water-based pressure-sensitive adhesive composition of the present invention comprises (meth) acrylic acid alkyl ester (a1) 50 to 99.89% by weight, carboxyl group-containing unsaturated monomer containing an alkyl group having 4 to 12 carbon atoms. (A2) 0.1 to 10% by weight, carbonyl group-containing unsaturated monomer (a3) 0.01 to 10% by weight, other unsaturated monomer (a4) 0 to 49.89% by weight A gel fraction comprising an acrylic resin having a glass transition temperature of more than −50 ° C. and not more than −25 ° C. obtained by emulsion polymerization of a monomer mixture in the presence of an anionic reactive emulsifier is less than 70% by weight. By containing the emulsion [A] made of acrylic resin, the hydrazine compound [B], and the phosphate ester compound [C], it is excellent in adhesive force, holding force, and constant load peeling force, and adheres over time. There is little force change, It has the effect that there is no adhesive residue after peeling, no contamination, and the change in adhesive performance with time is small, and when used as an adhesive for adhesive tapes or sheets and re-peeling labels, especially for decorative sheet adhesives It exhibits an excellent effect.

  The present invention relates to (meth) acrylic acid alkyl ester (a1) 50 to 99.89% by weight containing an alkyl group having 4 to 12 carbon atoms, carboxyl group-containing unsaturated monomer (a2) 0.1 to 10% by weight. %, Carbonyl group-containing unsaturated monomer (a3) 0.01 to 10% by weight, and other unsaturated monomer (a4) 0 to 49.89% by weight, Emulsion [A] obtained by emulsion polymerization in the presence of a functional emulsifier, and comprising an acrylic resin having a glass transition temperature of more than −50 ° C. and an acrylic resin having a temperature of −25 ° C. or less of less than 70% by weight, The present invention relates to a re-peelable aqueous pressure-sensitive adhesive composition comprising a hydrazine-based compound [B] and a phosphate ester-based compound [C].

  Emulsion [A] is a (meth) acrylic acid alkyl ester (a1) containing a C 4-12 alkyl group, a carboxyl group-containing unsaturated monomer (a2), a carbonyl group-containing unsaturated monomer (a3). ), And if necessary, a monomer mixture containing another unsaturated monomer (a4) is obtained by emulsion polymerization.

  The (meth) acrylic acid alkyl ester (a1) containing an alkyl group having 4 to 12 carbon atoms is not particularly limited. For example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl ( (Meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, isoundecyl (meth) acrylate, dodecyl (meth) acrylate, isododecyl (meth) acrylate, and the like. ) Acrylate, 2-ethylhexyl acrylate are preferably used. These may be used alone or in combination of two or more.

  The carboxyl group-containing unsaturated monomer (a2) is not particularly limited, and examples thereof 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. Is preferably used. These may be used alone or in combination of two or more.

  The carbonyl group-containing unsaturated monomer (a3) is not particularly limited, and examples thereof include diacetone acrylamide, 2- (acetoacetoxy) ethyl (meth) acrylate, and allyl acetoacetate. Among them, diacetone acrylamide is preferable. Used. These may be used alone or in combination of two or more.

  Furthermore, it does not specifically limit as another unsaturated monomer (a4), For example, carbon number, such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, etc. (Meth) acrylic acid alkyl ester having 1 to 3 alkyl groups, (meth) acrylic acid having an alkyl group having 13 or more carbon atoms such as tridecyl (meth) acrylate, isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, etc. Alkyl ester, dimethylaminoethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, acrylonitrile, methacrylonitrile, styrene, α-methyl Styrene, vinyl acetate, vinyl propionate, vinyl chloride, alkyl vinyl ether.

  Further, as the unsaturated monomer (a4), in addition to the above, a functional group-containing unsaturated monomer such as a hydroxyl group-containing unsaturated monomer, an epoxy group-containing unsaturated monomer, or an alkoxysilyl group-containing unsaturated monomer. A saturated monomer, an unsaturated monomer containing an amide group or a methylol group, a polyfunctional unsaturated monomer, or the like may be used.

  Examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.

  Examples of the epoxy group-containing unsaturated monomer include glycidyl (meth) acrylate and allyl glycidyl ether.

  Examples of the alkoxysilyl group-containing unsaturated monomer include (meth) acryloxyethyltrimethoxysilane, (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, and γ- (meth). Acryloxypropyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryl Roxypropyldimethylethoxysilane, γ- (meth) acryloxypropyltrichlorosilane, γ- (meth) acryloxypropylmethyldichlorosilane, γ- (meth) acryloxypropyldimethylchlorosilane, γ- (meth) acryloxypropyltripropio Sisilane, γ- (meth) acryloxypropylmethyldipropoxysilane, γ- (meth) acryloxypropyltributoxysilane, (meth) acryloxybutyltrimethoxysilane, (meth) acryloxypentyltrimethoxysilane, (meta ) Acryloxyhexyltrimethoxysilane, (meth) acryloxyhexyltriethoxysilane, (meth) acryloxyoctyltrimethoxysilane, (meth) acryloxydecyltrimethoxysilane, (meth) acryloxydecyltrimethoxysilane, (meth) ) Acryloxyoctadecyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripolopoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldipropo Shishiran, and the like.

  Examples of the unsaturated monomer containing an amide group or a methylol group include acrylamide, methacrylamide, N-methylol acrylamide, butoxy N-methylol acrylamide and the like.

  Examples of the polyfunctional unsaturated monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and propylene glycol di (meth). Acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) Acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) ) Acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, glycerin methacrylate acrylate, tris (meth) acryloyloxyphosphate, glycerin di (meth) acrylate, diallyl terephthalate, tetraallyloxyethane, divinyl Examples thereof include benzene and tri (meth) allyl isocyanurate.

  These unsaturated monomers are used alone or in combination of two or more.

  In the emulsion [A] used in the present invention, the (meth) acrylic acid alkyl ester (a1), the carboxyl group-containing unsaturated monomer (a2), the carbonyl group-containing unsaturated monomer (a3), and other non-functional monomers. The content of the saturated monomer (a4) is 50 to 99.89% by weight of the (meth) acrylic acid alkyl ester (a1) and 0.1 to 10% by weight of the carboxyl group-containing unsaturated monomer (a2). The carbonyl group-containing unsaturated monomer (a3) is 0.01 to 10% by weight, and the other unsaturated monomer (a4) is 0 to 49.89% by weight, preferably an alkyl (meth) acrylate. The ester (a1) is 55 to 99.65% by weight, the carboxyl group-containing unsaturated monomer (a2) is 0.3 to 5% by weight, and the carbonyl group-containing unsaturated monomer (a3) is 0.05 to 5%. % By weight The sum monomer (a4) is 0 to 44.65% by weight, more preferably 60 to 99.4% by weight of the (meth) acrylic acid alkyl ester (a1), and the carboxyl group-containing unsaturated monomer (a2). ) Is 0.5 to 3.0% by weight, the carbonyl group-containing unsaturated monomer (a3) is 0.1 to 3% by weight, and the other unsaturated monomer (a4) is 0 to 39.4% by weight. It is.

  When the (meth) acrylic acid alkyl ester (a1) is less than 50% by weight, sufficient adhesive strength and tack cannot be obtained, and when it exceeds 99.89% by weight, the carboxyl group-containing unsaturated monomer (a2) and the carbonyl The amount of the group-containing unsaturated monomer (a3) becomes small, so that the polymerization stability and mechanical stability are lowered, and sufficient removability is not obtained. If the carboxyl group-containing unsaturated monomer (a2) is less than 0.1% by weight, the polymerization stability and mechanical stability will decrease, and if it exceeds 10% by weight, the viscosity of the emulsion will increase and handling will become worse. Further, the adhesive strength and tack are also lowered. If the carbonyl group-containing unsaturated monomer (a3) is less than 0.01% by weight, sufficient removability cannot be obtained, and if it exceeds 10% by weight, the viscosity of the emulsion increases and handling becomes worse. Re-peelability will fall. When the monomer (a4) exceeds 49.89% by weight, the adhesive strength and tack are lowered.

  In the present invention, (meth) acrylic acid alkyl ester (a1), carboxyl group-containing unsaturated monomer (a2), carbonyl group-containing unsaturated monomer (a3), and other unsaturated monomers (a4) The emulsion [A] is obtained by emulsion polymerization using a monomer mixture containing). In emulsion polymerization, it is necessary to carry out in the presence of an anionic reactive emulsifier. By using an anionic reactive emulsifier, the constant load peel strength is improved, the water-resistant adhesiveness and the re-peelability are improved, and the effects of the present invention are remarkably exhibited.

  The anionic reactive emulsifier is not particularly limited as long as it is an anionic emulsifier and has reactivity, and examples thereof include those having the structures of the following general formulas (1) to (11). .

In the general formulas (1) to (11), R ₁ is an alkyl group, R ₂ is hydrogen or a methyl group, R ₃ is an alkylene group, n is an integer of 1 or more, and m and 1 are 1 or more that satisfies m + 1 = 3 An integer, X is either SO ₃ NH ₄ or SO ₃ Na.

  As the emulsifiers represented by the general formulas (1) to (11), specifically, “ADEKA rear soap SE-20N”, “ADEKA rear soap SE-10N”, “ADEKA rear soap PP-70”, “ADEKA rear "Soap PP-710", "Adekaria Soap SR-10", "Adekaria Soap SR-20" [above, manufactured by Asahi Denka Kogyo Co., Ltd.], "Eleminol JS-2", "Eleminol RS-30" [above "Latemul S-180A", "Latemul S-180", "Latemul PD-104" (manufactured by Kao Corporation), "Aqualon BC-05", "Aqualon BC" -10 "," Aqualon BC-20 "," Aquaron HS-05 "," Aquaron HS-10 "," Aquaron HS-20 "," New Frontier S-510 "," Aqua Emissions KH-05 "," Aqualon KH-10 "[or, Dai-ichi Kogyo Seiyaku Co., Ltd.]," phosphino - Le TX "[manufactured by Toho Chemical Industry Co., Ltd.]) commercially available products, and the like.

  Among the above-mentioned emulsifiers, in particular, those that do not contain an ethylene oxide chain in the structure and are neutralized with a monovalent metal salt (for example, sodium salt, potassium salt, etc.), specifically, “Eleminol JS-2 "Latemul S-180" or the like is most preferable in that it has excellent constant load peel force and little change in adhesive strength over time.

  The amount of the anionic reactive emulsifier used is preferably 0.5 to 10 parts by weight, more preferably 0.8 to 100 parts by weight with respect to 100 parts by weight of the monomer mixture (a1) to (a4). 7 parts by weight, particularly preferably 1 to 5 parts by weight. If the emulsifier is less than 0.5 parts by weight, the emulsion polymerization becomes unstable, and if it exceeds 10 parts by weight, the amount of unreacted emulsifier increases, which is not preferable because it causes a decrease in water-resistant adhesion and contamination of the adherend.

  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.

  Moreover, if necessary, an anionic emulsifier having no reactivity, a nonionic emulsifier having no reactivity, or a nonionic reactive emulsifier can be used in combination.

  Examples of the anionic emulsifier having no reactivity include alkyl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl phosphates, and the like. .

  Examples of the nonionic emulsifier having no reactivity include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, oxyethylene-oxypropylene block polymer, sorbitan fatty acid ester, polyoxyethylene fatty acid and the like.

  Nonionic reactive emulsifiers include, for example, those in the above general formulas (1) to (11) in which X is changed to hydrogen. Specifically, “Adekalia soap NE-10”, “Adekalia” "SOPE NE-20", "ADEKA rear soap NE-30", "ADEKA rear soap NE-40", "ADEKA rear soap ER-10", "ADEKA rear soap ER-20", "ADEKA rear soap ER-30" "Adekaria soap ER-40" [manufactured by Asahi Denka Kogyo Co., Ltd.], "AQUALON RN-10", "AQUALON RN-20", "AQUALON RN-30", "AQUALON RN-50" [ As mentioned above, commercial products, such as Daiichi Kogyo Seiyaku Co., Ltd.], are mentioned.

  In performing emulsion polymerization, a polymerization initiator is used. However, the polymerization initiator is not particularly limited, and any of water-soluble and oil-soluble can be used. Specifically, alkyl peroxide, 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, methylcyclohex Organic peroxides such as non-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, sodium persulfate Ammonium persulfate, hydrogen peroxide, ammonium (amine) salt of 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis (2-methylamidooxime) dihydrochloride, 2,2′-azobis (2-Methylbutanamide oxime) dihydrochloride tetrahydrate, 2,2′-azobis {2- Til-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] -propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], various Redox catalyst (in this case, as the oxidizing agent, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, p-methane hydroperoxide, etc. As the reducing agent, sodium sulfite, acidic sodium sulfite, Rongalite, ascorbic acid, etc. are used.) Among these, potassium persulfate, ammonium persulfate, sodium persulfate, redox are preferred because of their excellent polymerization stability. Catalyst (oxidizer: potassium persulfate, persulfate) (Ammonium acid, sodium persulfate, reducing agent: sodium sulfite, acidic sodium sulfite, Rongalite, ascorbic acid) and the like are suitable.

  It is preferable that the usage-amount of a polymerization initiator is 0.01-5 weight part with respect to 100 weight part of monomer mixtures of (a1)-(a4), Furthermore, 0.03-3 weight part. If it is less than 0.01 parts by weight, the polymerization rate is slow, and if it exceeds 5 parts by weight, the removability is lowered, which is not preferable.

  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)-(a4) previously, or may add to the emulsion liquid which consists of this monomer mixture. In the 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 emulsified and added.

  If necessary, a pH buffering agent may be used in combination for pH adjustment during polymerization. The amount of the pH buffer used is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the monomer mixture (a1) to (a4).

  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, phosphoric acid Examples include trisodium, sodium acetate, ammonium acetate, sodium formate, and ammonium formate.

  The amount of water used is preferably 20 to 400 parts by weight, more preferably 25 to 200 parts by weight, particularly preferably 30 to 100 parts by weight based on 100 parts by weight of the monomer mixture (a1) to (a4). 150 parts by weight. If the amount of water used is less than 20 parts by weight, the resulting resin composition will have a high viscosity, and the polymerization stability will also be reduced. If the amount exceeds 400 parts by weight, the concentration of the resulting resin composition will be low, resulting in film formation. This is not preferable because the drying property is reduced.

In the present invention, the monomer mixture (a1) to (a4) is polymerized with the initiator in the presence of an anionic reactive emulsifier to obtain an emulsion [A]. As the method,
(1) A method in which the whole amount of a monomer mixture, an emulsifier, water, etc. is charged and heated to polymerize.
(2) A method in which water, an emulsifier and a part of the monomer mixture are charged in a reaction can, polymerized by heating, and then the remaining monomer mixture is dropped or dividedly added to continue the polymerization.
(3) A method in which water, an emulsifier, and the like are charged in a reaction can and heated, and then the monomer mixture is added dropwise or dividedly and polymerized, and the polymerization temperature is easy to control. , (2) and (3) are preferred.

Although it does not specifically limit as polymerization conditions in the polymerization method of (1)-(3), For example,
In the method (1), a temperature range of about 40 to 100 ° C. is appropriate, and the reaction is carried out for about 1 to 8 hours after the start of temperature increase.
In the method (2), 1 to 50% by weight of the monomer mixture is polymerized at 40 to 90 ° C. for 0.1 to 4 hours, and then the remaining monomer mixture is dropped or divided over about 1 to 5 hours. After that, it is aged for about 1 to 3 hours at the same temperature.
In the method (3), water is charged into a polymerization can, the temperature is raised to 40 to 90 ° C., and the monomer mixture is dropped or dividedly added over about 2 to 5 hours, and then at the same temperature for about 1 to 3 hours. Mature.

  In the above polymerization method, the monomer mixture is preferably polymerized by dissolving the emulsifier (or a part of the emulsifier) in the monomer mixture or by preliminarily leaving it in the state of an O / W emulsion. This is preferable.

  The method for preparing the emulsified liquid is not particularly limited, but the above-described (a1) to (a4) are prepared after dissolving the emulsifier in water, and the mixed liquid is stirred and emulsified, or the emulsifier is dissolved in water and then stirred. However, the method etc. which prepare said (a1)-(a4) are mentioned. Stirring during emulsification of the emulsified liquid can be performed 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 emulsion [A] is obtained. In the present invention, the gel fraction of the obtained emulsion [A] needs to be less than 70% by weight, in particular, 20 to 60% by weight, more preferably 30 to 55%. % By weight is preferred. When the gel fraction is 70% by weight or more, sufficient base material adhesion cannot be obtained, which causes a residue of adhesive after re-peeling.

  A method for adjusting the gel fraction of the emulsion [A] to less than 70% is not particularly limited, but a chain transfer agent of alcohols such as methanol, ethanol and isopropyl alcohol and mercaptans such as dodecyl mercaptan and lauryl mercaptan is used during polymerization. The method of using together, the method of adjusting the quantity of a polymerization initiator, etc. are mentioned.

  The gel fraction of the emulsion [A] is the ratio of the solvent-insoluble component of the resin composition. In the 10 μm coating film of the emulsion [A] dried at 40 ° C. for 24 hours, It is calculated | required as a ratio (%) of the residual coating-film weight after immersion with respect to the coating-film weight before immersion when immersed at 24 degreeC for 24 hours.

  In addition, in the emulsion [A], it is necessary that the glass transition temperature of the acrylic resin produced by polymerization of the monomer mixture of (a1) to (a4) exceeds −50 ° C. and is −25 ° C. or less. In particular, it is preferably −30 to −45 ° C., more preferably −33 to −43 ° C. When the temperature is lower than -50 ° C, a sufficient constant load peeling force cannot be obtained. When the temperature exceeds -25 ° C, the initial adhesive strength is lowered, the constant load peeling force is lowered, and the removability is also lowered.

The glass transition temperature (Tg) is a value obtained by calculation from the following formula (I).
_{1 / Tg c = W 1 /} Tg 1 + W 2 / Tg 2 + W 3 / Tg 3 + ······· (I)
here,
W ₁ : weight fraction of monomer 1 in the copolymer,
W ₂ : weight fraction of monomer 2 in the copolymer,
W ₃ : weight fraction of monomer 3 in the copolymer,
Tg _c : Tg expressed in absolute temperature of the copolymer,
Tg ₁ : Tg represented by the absolute temperature of the homopolymer of monomer 1;
Tg ₂ : Tg represented by the absolute temperature of the homopolymer of monomer 2;
Tg ₃ : Tg represented by the absolute temperature of the homopolymer of monomer 3
Represents.

  The Tg of the homopolymer is, for example, poly n-butyl acrylate: −54 ° C., poly 2-ethylhexyl acrylate: −70 ° C., polymethyl methacrylate: 105 ° C., polyacrylic acid: 106 ° C., polydiacetone acrylamide: 87 Numerical values such as ° C are used.

  Further, in the obtained emulsion [A], the average particle size of the acrylic resin produced by polymerization of the monomer mixture of (a1) to (a4) is 1000 nm or less, particularly 100 to 700 nm, A fine particle of 120 to 500 nm is preferable. When the average particle diameter exceeds 1000 nm, the adhesion to the substrate is lowered, and as a result, the removability is lowered.

  Further, the solid content concentration of the emulsion [A] is preferably 10 to 70% by weight, particularly 20 to 65% by weight, from the viewpoints of drying property and coating property.

  The re-peelable water-based pressure-sensitive adhesive composition of the present invention needs to contain a hydrazine compound [B] as a crosslinking agent in addition to the emulsion [A]. Moreover, it is also preferable to use together what crosslinks with the carboxyl group of the carboxyl group-containing unsaturated monomer (a2) in emulsion [A] as needed, for example, an oxazoline type compound, a carbodiimide type compound, an epoxy type compound, for example. , Aziridine compounds, isocyanate compounds, melamine compounds, metal compounds such as metal complexes, amine compounds, and the like.

  The hydrazine compound [B] may be any compound having at least two or more hydrazide groups in the molecule. For example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid Examples thereof include dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide.

  Examples of the oxazoline compound include addition-polymerizable 2-oxazoline (for example, 2-isopropenyl-2-oxazoline) having a substituent having an unsaturated carbon-carbon bond at the 2-position carbon position and other unsaturated monomer. As a commercial product, “Epocross WS-500”, “Epocross WS-700”, “Epocross K-2010E”, “Epocross K-2020E” manufactured by Nippon Shokubai Co., Ltd., "Epocross K-2030E" etc. are mentioned.

  The carbodiimide-based compound may be any compound containing at least two carbodiimide groups. For example, “Carbodilite V-02”, “Carbodilite V-02-L2”, and “Carbodilite V-04” manufactured by Nisshinbo Industries, Ltd. ”,“ Carbodilite V-06 ”,“ Carbodilite E-01 ”,“ Carbodilite E-02 ”, and the like.

  Examples of the epoxy compound include bisphenol A / epichlorohydrin type epoxy resin, sorbitol polyglycidyl ether (for example, “Denacol EX-611”, “Denacol EX-612”, “Denacol EX-” manufactured by Nagase ChemteX Corporation). 614 "," Denacol EX-614B "," Denacol EX-622 ", etc.), polyglycerol polyglycidyl ether (for example," Denacol EX-512 "," Denacol EX-521 ", etc., manufactured by Nagase ChemteX Corporation) Pentaerythritol polyglycidyl ether (eg, “Denacol EX-411” manufactured by Nagase ChemteX Corp.), diglycerol polyglycidyl ether (eg, “Denacol EX-421” manufactured by Nagase ChemteX Corp.) , Grise Polyglycidyl ether (for example, “Denacol EX-313”, “Denacol EX-314”, etc., manufactured by Nagase ChemteX Corp.), trimethylolpropane polyglycidyl ether (for example, “Nagase ChemteX Co., Ltd.,“ Denacol EX-321 "), resorcinol diglycidyl ether (for example," Denacol EX-201 "manufactured by Nagase ChemteX Corporation), neopentyl glycol diglycidyl ether (for example," Nagase ChemteX Co., Ltd. " Denacol EX-211 "), 1,6-hexanediol diglycidyl ether (for example," Denacol EX-212 "manufactured by Nagase ChemteX Corporation), hydrogenated bisphenol A diglycidyl ether (for example, Nagase) Manufactured by Chemtex Co., Ltd. Nacol EX-252 ", etc.), ethylene glycol diglycidyl ether (eg," Denacol EX-810 "," Denacol EX-811 ", etc., manufactured by Nagase ChemteX Corporation), diethylene glycol diglycidyl ether (eg, Nagase ChemteX) "Denacol EX-850", "Denacol EX-851", etc., manufactured by Co., Ltd.), polyethylene glycol diglycidyl ether (for example, "Denacol EX-821", "Denacol EX-830", manufactured by Nagase ChemteX Corporation) , “Denacol EX-832”, “Denacol EX-841”, “Denacol EX-861”, etc.), propylene glycol diglycidyl ether (for example, “Denacol EX-911” manufactured by Nagase ChemteX Corporation), polypropylene, etc. Glycol digly Sidyl ether (for example, “Denacol EX-941”, “Denacol EX-920”, “Denacol EX-931” manufactured by Nagase ChemteX Corporation) and the like. Among these, an aqueous type is preferable.

  Any aziridine-based compound may be used as long as it contains at least two aziridine groups. Examples thereof include “Chemite DZ-33” and “Chemite DZ-22E” (manufactured by Nippon Shokubai Co., Ltd.).

  Examples of the isocyanate compound include toluylene diisocyanate, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, metaxylylene diisocyanate, 1,5-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated toluylene diisocyanate. , Hydrogenated xylylene diisocyanate, isophorone diisocyanate, tetramethylxylene diisocyanate, and other isocyanate compounds, bullet polyisocyanate compounds such as “Sumidule N” (manufactured by Sumitomo Bayer Urethane Co., Ltd.), “Desmodur IL”, “Desmodur” HL "(manufactured by Bayer AG)," Coronate EH "(manufactured by Nippon Polyurethane Industry Co., Ltd.) A polyisocyanate compound having a nurate ring, an adduct polyisocyanate compound such as “Sumijour L” (manufactured by Sumitomo Bayer Urethane Co., Ltd.), an adduct polyisocyanate compound such as “Coronate HL” (manufactured by Nippon Polyurethane Industry Co., Ltd.), “ Examples thereof include self-emulsifying water-dispersed polyisocyanate compounds such as “Aquanate 100”, “Aquanate 110”, “Aquanate 200”, and “Aquanate 210” (manufactured by Nippon Polyurethane Industry Co., Ltd.). Among these, a water dispersion type is preferable. A blocked isocyanate may also be used.

  Examples of melamine compounds include hexamethoxymethylol melamine and methoxymethylol urea.

  Examples of metal compounds include metal alkoxides such as tetraethyl titanate, tetraethyl zirconate, and aluminum isopropionate, and aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium, and the like. Examples include polyvalent metal acetylacetone and acetoacetate, metal chelate compounds of ethylenediaminetetraacetic acid coordination compounds, acetic acid-ammonium complex salts, ammonium-carbonate complex salts, and the like. Of these, the aqueous type is preferred.

  Examples of amine compounds include 1,3-diaminopropane, bis- (3-aminopropyl) ether, 1,2-bis- (3-aminopropoxy) ethane, 1,3-bis- (3-aminopropoxy)- Examples include 2,2-dimethylpropane and 1,4-diaminobutane.

  The content of the hydrazine compound [B] is such that the hydrazine compound per equivalent of carbonyl group contained in the acrylic resin produced by polymerization of the monomer mixture of (a1) to (a4) in the emulsion [A]. The ratio of hydrazide groups in [B] is preferably 0.001 to 1.0 equivalent, particularly 0.01 to 0.5 equivalent, and more preferably 0.05 to 0.3 equivalent. Preferably there is. If the content is less than 0.001 equivalent, crosslinking between particles becomes insufficient, resulting in poor removability, and the water-resistant adhesive strength is lowered, which is not preferable. If it exceeds 1.0 equivalent, the water re-peelability and the constant load peel strength are undesirably lowered.

  The re-peelable aqueous pressure-sensitive adhesive composition of the present invention further contains a phosphate ester compound [C] in addition to the emulsion [A] and the hydrazine compound [B]. Examples of phosphate ester compounds [C] include sesquioctyl phosphate, tributyl phosphate, trioctyl phosphate, tris (β-chloroethyl) phosphate, tris (β-chloropropyl) phosphate, tris (dichloropropyl) phosphate, triphenyl. Phosphate, tricresyl phosphate, tris (i-properphenyl) phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, tributoxyethyl phosphate, alkylpolyoxyethylene phosphate, alkylphenol polyoxyethylene phosphate, and these Neutralized salts such as sodium, potassium, ammonia, amine and the like can be mentioned. Among them, ammonia and neutralized salts of amines of each compound are preferable in terms of excellent water resistance. These phosphate ester compounds [C] can be used alone or in combination of two or more.

  The content of the phosphate ester compound [C] is preferably 0.01 to 5.0 parts by weight, particularly 0.03 to 1. part by weight based on 100 parts by weight of the solid content of the emulsion [A]. It is preferably 0 part by weight, more preferably 0.05 to 0.5 part by weight. If the phosphoric ester compound [C] is less than 0.01 parts by weight, the removability becomes poor, and if it exceeds 5.0 parts by weight, the constant load peel force and water-resistant adhesiveness are lowered, which is not preferable.

  Further, the re-peelable water-based pressure-sensitive adhesive composition of the present invention further contains a wetting agent [D], has no defects due to cissing and the like, and has a uniform coated surface, and has excellent substrate adhesion. It is preferable in terms of exhibiting. As the wetting agent [D], those capable of setting the static surface tension of a 0.1% aqueous solution to 40 mN / m or less are preferable, and those having a static surface tension of 35 mN / m or less are more preferable. Among them, anions such as sulfates and salts of higher alcohols, alkylbenzene sulfonates, polyoxyethylene alkylphenyl sulfonates, polyoxyethylene alkyl diphenyl ether sulfonates, alkyl diphenyl ether disulfonates, and dialkyl ester sulfonates of succinic acid Surfactants and nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene diphenyl ethers, polyoxyethylene-polyoxypropylene block copolymers, acetylenic diol surfactants However, it is preferable in that it is excellent in mixing stability at the time of addition and does not deteriorate the antifoaming property of the blended liquid.

  The content of the wetting agent [D] is such that the solid content of the wetting agent [D] is 0.05 to 3.0 parts by weight, particularly 0.1 to 100 parts by weight of the solid content of the emulsion [A]. The amount is preferably 1.5 parts by weight, more preferably 0.1 to 1.0 part by weight. If it is less than 0.05 part by weight, repelling occurs during coating, or a uniform coating surface cannot be obtained and the adhesion to the substrate is lowered, and if it exceeds 3.0 parts by weight, water-resistant adhesion is not achieved. In addition, the adhesion to the substrate is lowered, which is not preferable.

  Furthermore, the re-peelable water-based pressure-sensitive adhesive composition of the present invention includes a plasticizer (for example, liquid polybutene, mineral oil, lanolin, liquid polyisoprene, and liquid polyacrylate), antiseptic / antifungal agent, rust preventive, if necessary. Agent, antifreeze agent, high boiling point solvent, pigment, colorant, filler (zinc white, titanium white, calcium carbonate, clay, etc.), metal powder, antifoaming agent, thickener, adhesion control agent, UV absorber A weather resistance imparting agent such as a light stabilizer, an antioxidant, a tackifier resin, or the like can be added as appropriate, or can be added before or during the polymerization of the emulsion polymerization.

  The re-peelable water-based pressure-sensitive adhesive composition of the present invention thus obtained is often provided as a pressure-sensitive adhesive layer or a pressure-sensitive adhesive layer on a base sheet or the like, and is often put to practical use. In order to produce such an adhesive sheet, an adhesive tape, etc., first, the re-peelable water-based adhesive composition of the present invention is left as it is or adjusted to an appropriate concentration, and the treated surface of the substrate subjected to silicon treatment or the like It is possible to form a pressure-sensitive adhesive layer by coating it directly on the substrate or by drying it, for example, by heat treatment at 80 to 120 ° C. for 5 seconds to 10 minutes.

  The re-peelable water-based pressure-sensitive adhesive composition of the present invention can also be transferred onto a substrate after being applied to a release paper or a release film and dried.

  The substrate is not particularly limited. For example, polyvinyl chloride, polyvinylidene chloride, polybutene, polybutadiene, polyurethane, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polyethylene, polypropylene, ethylene-propylene copolymer, polymethyl. Examples thereof include films such as pentene and polybutylene terephthalate, metal foil, and porous materials such as paper and nonwoven fabric.

  Moreover, when using an olefin-type resin film for a base material, it is preferable to perform surface treatments, such as a high voltage corona discharge, in order to improve the base-material adhesiveness of an adhesive to the surface which should apply an adhesive.

  The thickness of the substrate is usually preferably 10 to 300 μm, particularly preferably 20 to 200 μm. On one side or both sides of the substrate, a layer made of the re-peelable aqueous pressure-sensitive adhesive composition of the present invention is preferably provided with a thickness of 1 to 100 μm, more preferably 3 to 70 μm, particularly preferably 5 to 50 μm, The form is a sheet or a tape.

  The re-peelable aqueous pressure-sensitive adhesive composition of the present invention is formed as a pressure-sensitive adhesive layer on a substrate by a general coating method. Specifically, it is applied by a coating method such as a bar coater, comma coater, die coater, roll coater, slit reverse coater, gravure coater, gravure kiss reverse coater, lip coater or the like.

  The re-peelable aqueous pressure-sensitive adhesive composition of the present invention is useful as a pressure-sensitive adhesive for a pressure-sensitive adhesive tape or sheet or a re-peelable label, and particularly useful as a pressure-sensitive adhesive for a decorative sheet.

  Hereinafter, a decorative sheet using the re-peelable pressure-sensitive adhesive composition of the present invention as a pressure-sensitive adhesive layer will be described.

  A decorative sheet is used for interiors of houses, specifically, interior decorations of buildings such as walls, ceilings, floors, surface decorations of furniture such as window frames, doors, handrails, furniture, or cabinets for low-power / OA equipment. Applications such as surface decoration of automobiles, interiors of vehicles such as automobiles and trains, interiors of airplanes, and cosmetics for window glass.

  For example, as shown in FIG. 1, the decorative sheet 1 includes a first primer layer 3, a pattern layer 4, an adhesive layer 5, a transparent resin layer 6, a concavo-convex pattern 7, a colored layer 8, and a surface on a substrate 2. The protective layer 9 is provided in this order, and the second primer layer 10 is provided on the back surface of the substrate 2. The pressure-sensitive adhesive layer 11 of the decorative sheet 1 is provided on the surface of the functional substrate on the second primer layer 10 side. Further, a release sheet 12 is provided on the surface of the pressure-sensitive adhesive layer 11.

  The base material 2 is an essential configuration of the decorative sheet 1 and is preferably formed of an olefin resin having a low environmental load from the viewpoint of environmental considerations among the above-described resins exemplified as the base material. A colorant, a heat stabilizer, a flame retardant, an ultraviolet absorber, a radical scavenger and the like are added to the resin forming the substrate 2 as necessary. The base material 2 is obtained by forming a film of the base material using a method such as calendering. The thickness of the substrate is 10 to 500 μm.

  The first primer layer 3 is arbitrarily provided between the substrate 2 and the pattern layer 4 and has a role of improving the adhesion between the substrate 2 and the pattern layer 4. As the resin for forming the first primer layer 3, the same resin as the colored binder used for forming the pattern layer 4 is used. Further, as described in JP 2000-211079 A, when the first primer layer 3 is formed of a thermoplastic resin containing an isocyanate-based crosslinking agent, the first primer layer 3 itself is This is preferable because it is a strong layer and the adhesion between the substrate 2 and the pattern layer 4 is improved. As the isocyanate-based crosslinking agent, aromatic polyisocyanate or aliphatic polyisocyanate is used. The first primer layer 3 is formed by applying a first primer layer forming material on the pattern layer 4. As a coating method, the same method as the pattern layer 4 described later can be used. The thickness of the first primer layer 3 is usually 0.1 to 15 μm.

  The pattern layer 4 is composed of a pattern layer and / or a solid layer. The solid layer is provided for the purpose of concealing the background of the substrate 2, and is usually formed as a solid solid colored layer having no pattern. The handle layer has a wood grain pattern, a stone pattern, or letters, and is formed on the solid layer. In some cases, the handle layer also functions as a solid layer. The pattern layer 4 is formed using a pattern layer forming material in which a coloring pigment for general pattern printing is contained in a colored binder.

  As the coloring pigment, a commonly used organic or inorganic pigment can be used. For example, inorganic pigments such as titanium white, zinc white, and petal, organic such as isoindolinone, Hansa Yellow A, and quinacridone. A pigment or the like is used. In particular, as described in JP-A No. 2000-211079, when titanium oxide (titanium white) is used as a color pigment, harmful light rays such as ultraviolet rays are blocked by the titanium oxide, and the lower layer of the pattern layer 4 It becomes difficult for ultraviolet rays or the like to reach a certain second primer layer 10. As a result, the adhesion strength of the second primer layer 10 does not change with time, and the adhesion between the decorative sheet 1 and the adherend having a curved surface or unevenness can be maintained. As a binder for the color pigment, chlorinated polyolefin such as chlorinated polyethylene or chlorinated polypropylene, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, thermoplastic resin such as acrylic resin or urethane resin, polyester, 2 A thermosetting resin such as a liquid curable urethane resin or an epoxy resin is used. In particular, as described in JP-A-9-314791, when a hindered amine light stabilizer is added to the resin forming the surface protective layer 9, chlorine is contained as a binder for the color pigment of the pattern layer 4. If the resin is not used, the light stabilizer is not affected by chlorine, and the weather resistance of the surface protective layer 9 is improved.

  The pattern layer 4 is formed by coating or printing a pattern layer forming material on the substrate 2. As a coating method, for example, various methods such as roll coating and curtain flow coating can be used. As printing methods, various methods such as relief printing such as gravure and letterpress, lithographic printing such as lithographic offset and dilitho printing, and stencil printing such as silk screen can be used. The thickness of the pattern layer 4 is usually 0.1 to 100 μm.

  The adhesive layer 5 is provided between the pattern layer 4 and the transparent resin layer 6 and has a role of improving the adhesion between the base material 2 and the transparent resin layer 6. The adhesive layer 5 is made of acrylic resin, urethane resin, polyester resin, synthetic rubber resin, natural rubber resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, epoxy resin, melamine resin, etc. The adhesive is applied onto the pattern layer 4 and formed. As a coating method, the same method as the pattern layer 4 can be used. The thickness of the adhesive layer 5 is usually 0.1 to 50 μm.

  The transparent resin layer 6 is also called a top resin layer, and protects the pattern layer 4 from scratches and the like, improves the surface strength of the decorative sheet 1 and gives a feeling of coating, etc., through the adhesive layer 5. It is laminated on the picture layer 4. The transparent resin layer 6 is preferably formed of an olefin resin among the exemplified resins, similarly to the substrate 2. Additives such as a colorant, a filler, an ultraviolet absorber, a light stabilizer, and a matting agent may be added to the resin forming the transparent resin layer 6 as necessary. The transparent resin layer 6 can be laminated on the adhesive layer 5 by separately forming a transparent resin sheet, by a melt extrusion coating method, or by other known methods. The thickness of the transparent resin layer 6 is usually 30 to 150 μm.

  On the surface of the transparent resin layer 6, as shown in FIG. 1, an uneven pattern 7 (embossed pattern) such as a grain conduit groove and a grain ring irregularity may be formed as necessary. Examples of means for forming the concavo-convex pattern 7 include an embossing method by heat and pressure, a T-die melt extrusion method, a hairline process, and a sandblast process.

  Further, a colored layer 8 may be formed in the recessed portion of the concavo-convex pattern 7. The colored layer 8 is formed by a wiping method using a coloring material and a colored binder used for forming the pattern layer 4. The formation by the wiping method is performed by applying the colorant ink to the entire surface including the recessed portion by the doctor blade coating method or the knife coating method, and then removing the colorant ink from the surface other than the recessed portion.

  The surface protective layer 9 is provided on the outermost surface of the decorative sheet 1 and has a role of improving the weather resistance of the decorative sheet 1. As with the base material 2, it is preferable that the resin is formed of an olefin resin among the exemplified resins. Further, the surface protective layer 9 contains methyl (meth) acrylate, hydroxyethyl (meth) acrylate, octyl (meth) acrylate or cyclohexyl (meth) acrylate described in JP 2000-280419 A as a copolymerization component. It may be formed by mixing an acrylic polyol-based main component and an isocyanate-based crosslinking agent. Here, (meth) acrylate means acrylate or methacrylate. When the surface protective layer 9 is formed of such a material, it is excellent in weather resistance, and the base material 2 made of an olefin-based resin and the surface protective layer 9 are not easily separated even in a high temperature and high humidity environment.

  The main component of the acrylic polyol system described in JP-A No. 2000-280419 is at least (a) one or both of octyl (meth) acrylate and cyclohexyl (meth) acrylate as a monomer, (b) general-purpose acrylate, and (C) It is obtained by copolymerizing a composition containing a hydroxyl group-containing acrylate. As octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate is preferably used. General-purpose acrylate monomers include methyl (meth) acrylate and ethyl (meth) acrylate. Examples of the hydroxyl group-containing acrylate include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. The composition of the monomer component in the acrylic polyol is preferably 30 to 65% by weight of component (a), 10 to 45% by weight of component (b), and 10 to 40% by weight of component (c). Among the above monomer components, the component (a) is preferably a combination of octyl acrylate and cyclohexyl acrylate (usually a mixing ratio of about 1: 2 to 2: 1 (weight ratio)), and the component (b) is methylmeta Acrylate is preferred, and component (c) is preferably 2-hydroxyethyl methacrylate. The isocyanate used for the isocyanate-based crosslinking agent described in JP-A-2000-280419 is a divalent or higher valent aliphatic isocyanate, alicyclic isocyanate, or aromatic isocyanate, and has good weather resistance, From the viewpoint of excellent discoloration prevention, an aliphatic isocyanate is preferable.

  In order to improve the weather resistance, an ultraviolet absorber made of metal oxide fine particles such as zinc oxide, a hindered amine light stabilizer and the like are added to the resin forming the surface protective layer 9 as necessary. Specific examples of the hindered amine light stabilizer include, for example, bis- (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis- (N-methyl-2,2,6,6-tetra). Methyl-4-piperidyl) sebacate and the like. The content of the hindered amine light stabilizer is preferably in the range of 0.1 to 3% by weight with respect to the total amount of the resin.

  The surface protective layer 9 is provided by coating a material for forming a surface protective layer, and as a coating method, a method such as gravure roll coating or roll coating can be used. The thickness of the surface protective layer 9 is usually 0.1 to 30 μm.

  The 2nd primer layer 10 is provided in the back surface of the decorative sheet 1, and has a role which makes it easy to adhere the decorative sheet 1 to the to-be-adhered body which has a curved surface or an unevenness | corrugation. As the resin for forming the second primer layer 10, the same resin as that used for forming the first primer layer 3 is used. Further, as described in JP-A No. 2001-205757, the second primer layer 10 is composed of a silica component (P1) having a large average particle size in the range of 2 to 4 μm and an average particle size. The weight ratio of silica content (P) consisting of silica content (P2) having a small average particle diameter in the range of 0.01 to 0.10 μm to resin content (R) is 0.4 <P It may be formed of an olefin resin contained so that /R<0.8. When the second primer layer 10 is formed of such a resin, the silica component (P) having an uneven surface having a sufficient contact area on the back surface of the decorative sheet 1 is stably dispersed. Adhesion with an adherend having a curved surface or unevenness is stabilized. The second primer layer 10 is formed by the same method as the first primer layer 3, and its thickness is usually 0.1 to 15 μm.

  The pressure-sensitive adhesive layer 11 is formed by the above-described forming method using the re-peelable aqueous pressure-sensitive adhesive composition of the present invention. Although the thickness of the pressure-sensitive adhesive layer 11 varies depending on the adherend, for example, it is preferably 15 to 150 μm from the viewpoint of adhesion to an adherend or the like having irregularities.

  As the release sheet 12, a release film obtained by applying a fluorine release agent or a silicone release agent to the surface of a polyethylene terephthalate film and performing a release treatment in addition to a commonly used release paper. Can be used. Moreover, in order to avoid blocking by the protrusion of the coated adhesive, the mold release process may be performed also to the surface which is not the coating surface of the adhesive of the peeling sheet 12. FIG.

  The re-peelable pressure-sensitive adhesive composition of the present invention comprises (meth) acrylic acid alkyl ester (a1) 50 to 99.89% by weight containing a C 4-12 alkyl group, a carboxyl group-containing unsaturated monomer ( a2) 0.1 to 10% by weight, carbonyl group-containing unsaturated monomer (a3) 0.01 to 10% by weight, other unsaturated monomer (a4) 0 to 49.89% by weight A body mixture obtained by emulsion polymerization in the presence of an anionic reactive emulsifier, an emulsion [A] having a glass transition temperature of more than −50 ° C. and not more than −25 ° C. and a gel fraction of less than 70% by weight, Since it contains a hydrazine compound [B] and a phosphate ester compound [C], it has excellent adhesive strength, holding power, and constant load peeling force, and has little change in adhesive strength over time. Adhesive performance over time with no adhesive residue or contamination It shows the small such effect of reduction.

  Hereinafter, the present invention will be specifically described with reference to examples.

  In the examples, “%” and “part” mean weight basis unless otherwise specified.

Example 1
n-butyl acrylate (a1) 83.0 parts, acrylic acid (a2) 2.0 parts, diacetone acrylamide (a3) 0.5 parts, methyl methacrylate (a4) 14.5 parts, 1-dodecane as a chain transfer agent 0.05 part of thiol, anionic reactive emulsifier (manufactured by Sanyo Chemical Industries, Ltd., “Eleminol JS-2”: active ingredient 38%, structure of the above general formula (3), R ₁ : alkyl group, X: (SO ₃ Na) 3.16 parts and 41.4 parts of water were mixed and stirred to obtain an emulsion comprising a monomer mixture.

Next, in a flask equipped with a cooling tube and a stirring blade, an anionic reactive emulsifier (manufactured by Sanyo Chemical Industries, Ltd., “Eleminol JS-2”: active ingredient 38%, with the structure of the above general formula (3), R ₁ : alkyl group, X: SO ₃ Na) 0.26 part, sodium acetate trihydrate 0.41 part, 31.7 parts of water as a pH buffer, and after heating to 75 ° C. with stirring, 5% (7.23 parts) of the above emulsion was added. Further, after the temperature was raised to 80 ° C., 0.8 part of 3% potassium persulfate aqueous solution was added to perform emulsion polymerization, and then 15 minutes later, the remaining 95% (137.38 parts) of the above emulsion and 3% A mixed solution obtained by mixing 3.2 parts of an aqueous potassium persulfate solution was added dropwise over 3.5 hours. After completion of the dropwise addition, stirring was continued for 2 hours while maintaining the temperature at 80 ° C, followed by cooling to 60 ° C and adding 2.4 parts of a 10% aqueous ammonia solution to neutralize the acid groups. Then, it cools to 55 degreeC, 0.5 part of 10% aqueous solution of tertiary butyl hydroperoxide (Nippon Yushi Co., Ltd. "Perbutyl H-69") and 0.5 part of 10% L-ascorbic acid aqueous solution are added. After each addition and reaction for 15 minutes, 0.5 parts of 10% aqueous solution and 10% L-ascorbic acid aqueous solution of tertiary butyl hydroperoxide (Nippon Yushi Co., Ltd., “Perbutyl H-69”) were again used. 0.5 parts of each was added and allowed to react for 15 minutes. After cooling to 30 ° C., the pH was adjusted to 8.0 with a 10% aqueous ammonia solution and filtered through a 200-mesh wire mesh to obtain an emulsion [A] (gel fraction 50%, solid content 55.0%, viscosity 2000 mPa · s [B-type viscometer, 12 rpm, 25 ° C.], glass transition temperature-37.2 ° C., average particle size 210 nm).

  Further, in the obtained emulsion [A], a 5% aqueous solution of adipic acid dihydrazide as a hydrazine compound [B] was 0.42 parts (0.021 parts as an active ingredient) with respect to 100 parts of the solid content of the emulsion, phosphorus 0.15 parts of sesquioctyl phosphate triethanolamine salt (“ES-N” manufactured by Kitahiro Chemical Co., Ltd.) as the acid ester compound [C], and “SN wet 970” (San Nopco Co., Ltd.) as the wetting agent [D] Manufactured, solid content: 50%) 0.5 part (0.25 part as solid content), "SN deformer JK" (manufactured by San Nopco Co., Ltd.) 0.1 part as an antifoaming agent was added and mixed, and then the viscosity of the blended solution "UH-541" (manufactured by Asahi Denka Kogyo Co., Ltd.) is added and mixed as a thickener so that the viscosity becomes 8000 mPa · s (B-type viscometer, 12 rpm, 25 ° C). To obtain an aqueous PSA composition.

  Using the obtained re-peelable water-based pressure-sensitive adhesive composition, a decorative sheet was prepared as follows, and the following evaluation was performed.

[Production of decorative sheet]
Using the obtained re-peelable water-based pressure-sensitive adhesive composition, an adhesive decorative sheet was prepared as follows.

  First, a decorative sheet (functional base material) not subjected to adhesive processing was prepared by the following method.

  A polyethylene-based colored sheet (thickness: 60 μm) manufactured by Mitsubishi Chemical MKV Co., Ltd. is used as the base sheet 2 and subjected to corona discharge treatment on each of the front and back surfaces, and then a two-part curable primer coating liquid (acrylic) A mixture of polyol and tolylene diisocyanate at a ratio of 100: 5 (weight ratio) was applied by a gravure coating method to form a back primer layer 10 having a thickness of 2 μm after drying with a diluting solvent.

Further, on the opposite side, a solid ink and a pattern ink having the following composition were applied and dried by a gravure printing method to form a pattern layer 4 in which a solid ink layer and a pattern ink layer were formed in this order. The solid printing ink is a polyurethane-acrylic block copolymer acrylic urethane system obtained by copolymerizing 20% by weight of a polyurethane azo polymer, which is an addition product of azodiol, diol and diisocyanate, and n-butyl methacrylate as a binder. What mixed resin and hexamethylene diisocyanate in the ratio of 100: 6 (weight ratio) was used, and the titanium white, the petal, and chrome lead were added to this as a coloring agent. For the pattern printing ink, an acrylic urethane binder similar to that for the solid printing ink is added with a petrol and carbon black as a pigment, and the dilution solvent is 1: 1 of ethyl acetate and methyl isobutyl ketone (MIBK). The mixed solvent was used. Further, an adhesive layer 5 of about 3 g / m ² was formed on the pattern ink layer.

  Subsequently, on the adhesive layer 5, maleic acid-modified polypropylene resin (10 μm) and random copolymerized polypropylene, phenolic antioxidant 0.2 wt%, hindered amine light stabilizer 0.3 wt%, blocking prevention Resin (70 μm) to which 0.2% by weight of each agent was added was co-extruded by ozone irradiation with T-die so that the adhesive layer 5 side became maleic acid-modified polypropylene and heated to about 80 μm. A transparent resin layer 6 was laminated. The surface of the transparent resin layer 6 is made uneven by hot embossing at about 160 ° C., and further, corona discharge treatment is performed on the surface provided with the unevenness, and then the embossed recess is filled with colored ink by wiping. 8 was formed. A surface protective layer 9 was formed thereon to produce a decorative sheet of Example 1.

The re-peelable pressure-sensitive adhesive composition obtained above is applied with an applicator to the release-treated surface of release paper (Lintec KP11 Maru D) so that the thickness of the pressure-sensitive adhesive layer after drying is 40 g / m ^2. This was dried at 90 ° C. for 3 minutes. Then, after laminating the surface of the non-adhesive decorative sheet on which the primer layer was formed and the surface of the release paper on which the adhesive layer was formed, and aging at room temperature for 1 week, Example 1 An adhesive processed sheet with a release sheet was obtained.

  The following evaluation was performed about the obtained decorative sheet.

(Adhesive force)
One day after the release sheet was peeled from the obtained adhesive decorative sheet and adhered to a SUS304 polishing plate by reciprocating a 2 kg roller at 23 ° C. and 50% RH, a method for measuring the adhesive strength of JIS Z 0237 The 180 degree peel strength (N / 25 mm) is measured according to the above.

(Adhesive strength after time)
The release sheet was peeled from the obtained adhesive decorative sheet, adhered to a SUS304 polishing plate by reciprocating 2 kg rollers at 23 ° C. and 50% RH, and then left (a) for 30 days at 70 ° C. ( b) About 180 degree peel strength (N / 25mm) was measured according to the measuring method of the adhesive force of JISZ0237 about 30 days after leaving to stand in 40 degreeC warm water.

(Contamination resistance after aging)
After the above (a) after standing for 30 days at 70 ° C. and (b) after measuring the adhesive strength after standing for 30 days in warm water at 40 ° C., the degree of contamination of the adherend surface was visually observed, Contamination is evaluated as follows.
○: No contamination was observed.
(Triangle | delta): The mark was recognized.
X: Adhesive residue was recognized.

(Constant load peeling force)
The pressure-sensitive adhesive decorative sheet (size width: 20 mm × sticking length: 50 mm) is attached to an adherend (SUS board) by pressurizing and reciprocating 2 kg of rubber rollers at room temperature, and then left at 40 ° C. for 30 minutes. The sample is peeled in the direction of 90 degrees under a load, and the peel length after 1 hour or the drop time (min) is measured.

(Holding power)
The obtained adhesive decorative sheet was attached to a stainless steel plate so that the area was 25 mm × 25 mm, and a load of 1 kg was applied under the condition of 40 ° C., according to the holding power measurement method of JIS Z 0237. Measure the deviation (mm) or the drop time (min) after 24 hours.

Examples 2-8, Comparative Examples 1-6
An emulsion [A] was obtained in the same manner as in Example 1 except that the composition was changed as shown in Tables 1 to 3. Further, as shown in Tables 1 to 3, the obtained emulsion [A] was the same as Example 1 except that hydrazine compound [B], phosphate ester compound [C] and wetting agent [D] were added. Then, a re-peelable water-based pressure-sensitive adhesive composition was obtained, and the obtained re-peelable water-based pressure-sensitive adhesive composition was evaluated in the same manner as in Example 1.

  Table 4 shows the evaluation results of Examples and Comparative Examples.

  In addition, the numerical value of the monomer mixture in Tables 1-3, a chain transfer agent, an emulsifier, water, a pH buffer, a hydrazine compound, a phosphate ester compound, and a wetting agent shows a compounding quantity (part). However, the numerical value in [] of a crosslinking agent shows the equivalent number of the functional group of the hydrazine type compound per 1 equivalent of carbonyl groups in acrylic resin.

(emulsifier)
・ JS-2 (“Eleminol JS-2” manufactured by Sanyo Chemical Industries, Ltd .: active ingredient 38%)
RAA-11902 ("RAA-11902" manufactured by Nippon Emulsifier Co., Ltd .: 30% active ingredient, non-reactive anionic emulsifier)

(Hydrazine compounds)
ADH ("Adipic acid dihydrazide" manufactured by Otsuka Chemical Co., Ltd .: added as a 5% aqueous solution)

(Phosphate ester compounds)
ES-N (sesquioctyl phosphate triethanolamine salt; “ES-N” manufactured by Kitahiro Chemical Co., Ltd .: active ingredient 100%)

(Wetting agent)
SN-970 (nonionic surfactant; “SN wet 970” manufactured by San Nopco Co., Ltd .: solid content 50%)

It is the figure which showed the cross section of one Embodiment of the decorative sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cosmetic sheet 2 Base material 3 1st primer layer 4 Picture layer 5 Adhesive layer 6 Transparent resin layer 7 Unevenness pattern 8 Colored layer 9 Surface protection layer 10 2nd primer layer 11 Adhesive layer 12 Release sheet

Claims (7)

[A] (a1) 50 to 99.89% by weight of (meth) acrylic acid alkyl ester containing an alkyl group having 4 to 12 carbon atoms, (a2) 0.1 to 10% by weight of a carboxyl group-containing unsaturated monomer A monomer mixture containing (a3) 0.01 to 10% by weight of a carbonyl group-containing unsaturated monomer and (a4) 0 to 49.89% by weight of another unsaturated monomer. An emulsion obtained by emulsion polymerization in the presence of an emulsifier and having a glass fraction of an acrylic resin having a glass transition temperature higher than −50 ° C. and lower than −25 ° C. and having a gel fraction of less than 70% by weight, [B] a hydrazine compound, and [C] A re-peelable water-based pressure-sensitive adhesive composition comprising a phosphate ester compound. The re-peelable aqueous pressure-sensitive adhesive composition according to claim 1, wherein the anionic reactive emulsifier is a compound neutralized with a monovalent metal salt. The releasable aqueous pressure-sensitive adhesive composition according to claim 1 or 2, wherein the anionic reactive emulsifier is a compound containing no ethylene oxide chain in the structure. The (meth) acrylic acid alkyl ester (a1) in which the hydrazide group in the hydrazine compound [B] contains an alkyl group having 4 to 12 carbon atoms in the emulsion [A], a carboxyl group-containing unsaturated monomer (a2 ), Carbonyl group-containing unsaturated monomer (a3), and 0.001 to 1.0 equivalent per carbonyl group equivalent contained in the acrylic resin composed of the other unsaturated monomer (a4). The re-peelable water-based pressure-sensitive adhesive composition according to claim 1, 2, or 3. The content of the phosphate ester compound [C] is 0.01 to 5.0 parts by weight with respect to 100 parts by weight of the solid content of the emulsion [A]. Or the re-peelable water-based pressure-sensitive adhesive composition according to 4. Furthermore, [D] wetting agent is contained, The releasable water-based adhesive composition of Claim 1, 2, 3, 4 or 5 characterized by the above-mentioned. A decorative sheet comprising a pressure-sensitive adhesive layer formed from the re-peelable water-based pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5 or 6.

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