JP7356898B2 - Resin emulsion for water-based ink - Google Patents

Description

The present invention relates to a resin emulsion for aqueous ink. More specifically, the present invention relates to a resin emulsion for aqueous ink, a method for producing the same, and an aqueous ink containing the resin emulsion for aqueous ink. The water-based ink of the present invention can be used, for example, as an inkjet water-based ink, a flexographic printing ink, an offset printing ink, a lithographic printing ink, a gravure printing ink, a screen printing ink, and especially as an inkjet water-based ink. It can be suitably used.

Inks are broadly classified into organic solvent-based inks in which an organic solvent is used as the main component of the solvent, and aqueous inks in which water is used as the main solvent component.

Organic solvent-based ink compositions have good water resistance because the main component of the solvent is an organic solvent. Because of this, water-based inks are attracting attention.

An aqueous ink composition containing a resin emulsion containing emulsion particles as an essential component, as an aqueous ink composition that has excellent storage stability and forms a coating film that is comprehensively excellent in curl prevention, scratch resistance, water resistance, and weather resistance. The ink composition further contains at least one water-insoluble curable compound selected from the group consisting of water-insoluble curable monomers and water-insoluble curable oligomers, and constitutes the emulsion particles. An aqueous ink composition has been proposed in which the glass transition temperature of the polymer is 0 to 120°C, and the minimum film forming temperature of the aqueous ink composition is 0 to 30°C (for example, Patent Document 1 reference).

The water-based ink composition forms a coating film that is comprehensively excellent in anti-curling properties, scratch resistance, water resistance, and weather resistance, so it can be used, for example, on paper, resin sheets or films, metal plates, wood plates, Desired information such as characters, patterns, colors, etc. are formed on a base material made of materials such as leather by inkjet printing, flexographic printing, offset printing, lithographic printing, gravure printing, screen printing, ink ribbon, etc. It can be suitably used in industrial inks such as printing inks when imparting design properties, scratch resistance, water resistance, weather resistance, etc. to objects.

However, in recent years, the images formed by ink are uniform, have excellent adhesion to substrates and blocking resistance, and have little change in viscosity due to changes in the nonvolatile content of the ink. It is desired to develop an aqueous ink that can be continuously and stably ejected from a nozzle head when used.

Patent No. 6258662

The present invention has been made in view of the above-mentioned prior art, and provides uniform images formed by ink, excellent adhesion to substrates and blocking resistance, and viscosity due to changes in the nonvolatile content contained in the ink. For example, water-based ink that can be continuously and stably ejected from a nozzle head when used as an inkjet water-based ink, and water-based ink that can be suitably used for the water-based ink. An object of the present invention is to provide a resin emulsion and a method for producing the same.

The present invention
(1) A resin emulsion for water-based ink containing emulsion particles, in which the content of a low molecular weight polymer having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink is 0.01. A resin emulsion for water-based ink, characterized in that the content is ~3% by mass,
(2) A method for producing a resin emulsion for an aqueous ink containing emulsion particles, wherein the content of a low molecular weight polymer having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for an aqueous ink is 0. 01 to 3% by mass, and (3) an aqueous resin emulsion characterized by containing the resin emulsion for aqueous ink according to (1) above and a colorant. Regarding ink.

According to the present invention, an image formed with a water-based ink is uniform, has excellent adhesion to a substrate and anti-blocking property, and has a small change in viscosity due to a change in non-volatile content contained in the ink. Provided are an aqueous ink that can be continuously and stably ejected from a nozzle head when used as an aqueous ink, a resin emulsion for an aqueous ink that can be suitably used in the aqueous ink, and a method for producing the same. Ru.

1 is a graph illustrating one embodiment of a gel permeation chromatography chart for a polymer, created by gel permeation chromatography.

The resin emulsion for water-based ink of the present invention is a resin emulsion for water-based ink containing emulsion particles, and is made of a low molecular weight polymer having a weight average molecular weight of 500 to 1000 among all polymers contained in the resin emulsion for water-based ink. It is characterized by a content of 0.01 to 3% by mass. Further, the method for producing a resin emulsion for water-based ink of the present invention is a method for producing a resin emulsion for water-based ink containing emulsion particles, wherein the weight average molecular weight of all polymers contained in the resin emulsion for water-based ink is 500 to 500. The content of the low molecular weight polymer, which is 1000% by weight, is adjusted to 0.01 to 3% by mass.

Since the present invention has the above-mentioned configuration, the property that the image formed by the water-based ink is uniform (hereinafter referred to as image uniformity), the adhesion to the base material, the blocking resistance, and the nonvolatile content contained in the ink can be improved. The property that the viscosity changes little due to change (hereinafter referred to as viscosity change stability), and the property that allows the ink to be continuously and stably ejected from the nozzle head when used as an aqueous inkjet ink (hereinafter referred to as continuous ejection stability) superior in sex).

In the present invention, all polymers contained in the resin emulsion for water-based ink include not only the polymers constituting the emulsion particles contained in the resin emulsion for water-based ink, but also the polymers other than the polymers contained in the emulsion particles. If the resin emulsion for water-based ink contains other polymers such as water-soluble polymers and polymer emulsifiers, the polymers constituting the emulsion particles and these other polymers may be included. It is a concept that includes polymers. Therefore, all the polymers contained in the resin emulsion for water-based ink mean all the polymers contained in the resin emulsion for water-based ink.

Emulsion particles can be prepared by emulsion polymerization of monomer components. Monomers used in the monomer component include monofunctional monomers and polyfunctional monomers. The monofunctional monomer and the polyfunctional monomer may be used alone or in combination. Although it is possible to use only a polyfunctional monomer as a monomer component, usually only a monofunctional monomer or a combination of a monofunctional monomer and a polyfunctional monomer are used.

Representative examples of monofunctional monomers include radically polymerizable monomers such as ethylenically unsaturated monomers. Examples of ethylenically unsaturated monomers include alkyl (meth)acrylates, hydroxyl group-containing (meth)acrylates, aralkyl (meth)acrylates, alkoxyalkyl (meth)acrylates, carboxyl group-containing monomers, oxo group-containing monomers, and fluorine atom-containing monomers. , nitrogen atom-containing monomers, styrene monomers, epoxy group-containing monomers, silane group-containing monomers, carbonyl group-containing monomers, aziridinyl group-containing monomers, etc., but the present invention is not limited to these examples. These ethylenically unsaturated monomers may be used alone or in combination of two or more.

In the present invention, "(meth)acrylate" means "acrylate" or "methacrylate". "(Meth)acrylic" means "acrylic" or "methacrylic". Moreover, "(meth)acryloyl" means "acryloyl" or "methacryloyl".

Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, tridecyl (meth)acrylate, n-lauryl (meth)acrylate, dodecyl (meth)acrylate Acrylate, stearyl (meth)acrylate, 2-(acetoacetoxy)ethyl (meth)acrylate, 2-ethylhexylcarbitol (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-methylcyclohexylmethyl ( Examples include alkyl (meth)acrylates in which the ester group has 1 to 18 carbon atoms, such as meth)acrylate, tert-butylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate; however, the present invention is not limited to such examples. It is not limited. These monomers may be used alone or in combination of two or more.

Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxy Examples include (meth)acrylates containing hydroxyl groups in which the ester group has 1 to 18 carbon atoms, such as butyl (meth)acrylate and caprolactone-modified hydroxy (meth)acrylate; however, the present invention is not limited to these examples. do not have. These monomers may be used alone or in combination of two or more.

Examples of aralkyl (meth)acrylates include aralkyl groups having an aralkyl group having 7 to 18 carbon atoms, such as benzyl (meth)acrylate, phenylethyl (meth)acrylate, methylbenzyl (meth)acrylate, and naphthylmethyl (meth)acrylate. Examples include (meth)acrylate, but the present invention is not limited to such examples. These monomers may be used alone or in combination of two or more.

Examples of alkoxyalkyl (meth)acrylates include methoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, trimethylolpropane tripropoxy (meth)acrylate, etc. However, the invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, maleic acid monomethyl ester, maleic acid monobutyl ester, itaconic acid monomethyl ester, Examples include carboxyl group-containing aliphatic monomers such as itaconic acid monobutyl ester, vinyl benzoic acid, oxalic acid monohydroxyethyl (meth)acrylate, and carboxyl group-terminated caprolactone-modified (meth)acrylate. It is not limited to only. These monomers may be used alone or in combination of two or more. Among these carboxyl group-containing monomers, acrylic acid, methacrylic acid and itaconic acid are preferred, and acrylic acid and methacrylic acid are more preferred, from the viewpoint of improving the dispersion stability of emulsion particles.

Examples of oxo group-containing monomers include (di)ethylene glycol (methoxy) (meth)acrylates such as ethylene glycol (meth)acrylate, ethylene glycol methoxy (meth)acrylate, diethylene glycol (meth)acrylate, and diethylene glycol methoxy (meth)acrylate. However, the present invention is not limited to only such examples. These monomers may be used alone or in combination of two or more.

Examples of fluorine atom-containing monomers include trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, perfluorobutylethyl (meth)acrylate, and perfluoroisononylethyl (meth)acrylate. Examples include acrylates, fluorine atom-containing alkyl (meth)acrylates having a fluorine atom in the ester moiety, such as perfluorooctylethyl (meth)acrylate, but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of nitrogen atom-containing monomers include (meth)acrylamide, N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, Nn-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, methylenebis(meth)acrylamide, N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide, dimethylaminoethyl(meth)acrylamide, N,N-dimethylaminopropylacrylamide, diacetone Acrylamide compounds such as acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, nitrogen atom-containing (meth)acrylate compounds such as ethylene oxide addition (meth)acrylate of morpholine, N-vinylpyrrolidone, N-vinylpyridine , N-vinylimidazole, N-vinylpyrrole, N-vinyloxazolidone, N-vinylsuccinimide, N-vinylmethylcarbamate, N,N-methylvinylacetamide, (meth)acryloyloxyethyltrimethylammonium chloride, 2-isopropenyl -2-oxazoline, 2-vinyl-2-oxazoline, (meth)acrylonitrile, etc., but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of styrenic monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-ethoxystyrene, m-ethoxystyrene, p-ethoxystyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, o-tert-butoxystyrene, m-tert-butoxystyrene, p -tert-butoxystyrene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene, vinyltoluene, etc., but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more. Styrenic monomers have functional groups such as alkyl groups such as methyl groups and tert-butyl groups, nitro groups, nitrile groups, alkoxyl groups, acyl groups, sulfone groups, hydroxyl groups, and halogen atoms in the benzene ring. good. Among the styrene monomers, styrene is preferred from the viewpoint of obtaining an aqueous ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability.

Examples of epoxy group-containing monomers include epoxy groups such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, glycidyl allyl ether, oxocyclohexylmethyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl (meth)acrylate. Examples include group-containing (meth)acrylates, but the present invention is not limited to such examples. These monomers may be used alone or in combination of two or more.

Examples of the silane group-containing monomer include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, 2-styrylethyltrimethoxysilane, vinyltrichlorosilane, Examples include γ-(meth)acryloyloxypropylhydroxysilane, γ-(meth)acryloyloxypropylmethylhydroxysilane, but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of carbonyl group-containing monomers include acrolein, homylstyrene, vinyl ethyl ketone, (meth)acryloxyalkylpropenal, acetonyl (meth)acrylate, diacetone (meth)acrylate, and 2-hydroxypropyl (meth)acrylate acetylacetate. , butanediol-1,4-acrylate acetylacetate, etc., but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of the aziridinyl group-containing monomer include (meth)acryloylaziridine and 2-aziridinylethyl (meth)acrylate, but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1, 6-hexanediol di(meth)acrylate, ethylene oxide-modified 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, propylene oxide-modified neopentyl glycol di(meth)acrylate, tripropylene Di(meth)acrylate of polyhydric alcohol having 1 to 10 carbon atoms, such as glycol di(meth)acrylate; polyethylene glycol di(meth)acrylate with an added mole of ethylene oxide of 2 to 50, and a polyethylene glycol di(meth)acrylate with an added mole of propylene oxide of 2 ~50 polypropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and other alkyl di(meth)acrylates with 2 to 50 moles of alkylene oxide groups having 2 to 4 carbon atoms; ethoxylated glycerin triacrylate; (meth)acrylate, propylene oxide modified glycerol tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol monohydroxy tri(meth)acrylate, trimethylolpropane triethoxy Tri(meth)acrylates of polyhydric alcohols having 1 to 10 carbon atoms such as tri(meth)acrylate; pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, etc. Tetra(meth)acrylate of polyhydric alcohol having 1 to 10 carbon atoms; Penta(meth)acrylate of polyhydric alcohol having 1 to 10 carbon atoms such as pentaerythritol penta(meth)acrylate, dipentaerythritol (monohydroxy) penta(meth)acrylate meth)acrylate; Hexa(meth)acrylate of polyhydric alcohol having 1 to 10 carbon atoms such as pentaerythritol hexa(meth)acrylate; Bisphenol A di(meth)acrylate, 2-(2'-vinyloxyethoxyethyl)(meth)acrylate; ) acrylates, epoxy group-containing (meth)acrylates such as epoxy (meth)acrylates; polyfunctional (meth)acrylates such as urethane (meth)acrylates, but are not limited to these examples. These polyfunctional monomers may be used alone, or two or more types may be used in combination.

In the present invention, from the viewpoint of imparting ultraviolet stability or ultraviolet absorption to the emulsion particles, it is possible to incorporate ultraviolet stable monomers, ultraviolet absorbing monomers, etc. into the monomer components within a range that does not impede the purpose of the present invention. preferable.

Examples of UV-stable monomers include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, -(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyl-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4- (meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino -2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2 , 6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2, Examples include 6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more. Among these UV-stable monomers, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethyl Piperidyl group-containing (meth)acrylates such as piperidine and 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine are preferred.

Examples of the ultraviolet absorbing monomer include benzotriazole ultraviolet absorbing monomers and benzophenone ultraviolet absorbing monomers, but the present invention is not limited to these examples. These monomers may be used alone or in combination of two or more.

Examples of benzotriazole-based ultraviolet absorbing monomers include 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth) ) acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy -5'-(meth)acryloylaminomethyl-5'-tert-octylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxypropylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyhexylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl ]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy -5'-tert-butyl-3'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H -Benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-cyano-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethyl phenyl]-5-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethoxy)-3'-tert-butylphenyl]-4-tert-butyl Examples include -2H-benzotriazole, but the present invention is not limited to such examples. These monomers may be used alone or in combination of two or more.

Examples of benzophenone-based ultraviolet absorbing monomers include 2-hydroxy-4-(meth)acryloyloxybenzophenone, 2-hydroxy-4-[2-hydroxy-3-(meth)acryloyloxy]propoxybenzophenone, and 2-hydroxy- 4-[2-(meth)acryloyloxy]ethoxybenzophenone, 2-hydroxy-4-[3-(meth)acryloyloxy-2-hydroxypropoxy]benzophenone, 2-hydroxy-3-tert-butyl-4-[2 -(meth)acryloyloxy]butoxybenzophenone and the like, but the present invention is not limited to such examples. These monomers may be used alone or in combination of two or more.

Monomer components include alkyl (meth)acrylates, hydroxyl group-containing (meth)acrylates, and alkyl (meth)acrylates to obtain a water-based ink that is comprehensively superior in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. Preferably contains an acrylate, a styrene monomer, and a UV-stable monomer, an alkyl (meth)acrylate whose alkyl group has 1 to 8 carbon atoms, and a hydroxyalkyl (meth)acrylate whose alkyl group has 2 to 4 carbon atoms. , styrene and piperidyl group-containing (meth)acrylate.

The content of alkyl (meth)acrylate in the monomer component is preferable from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. is 35 to 85% by weight, more preferably 40 to 80% by weight. The content of alkyl (meth)acrylate, preferably methyl (meth)acrylate, in which the alkyl group has 1 to 3 carbon atoms in the monomer component is determined to improve image uniformity, adhesion to the substrate, blocking resistance, and viscosity change stability. From the viewpoint of obtaining an aqueous ink with comprehensively excellent continuous ejection stability, the content is preferably 10 to 60% by mass, more preferably 15 to 55% by mass. In addition, the content of alkyl (meth)acrylate in which the alkyl group has 4 to 8 carbon atoms in the monomer component is important for image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous discharge stability. From the viewpoint of obtaining an overall excellent aqueous ink, the content is preferably 10 to 40% by mass, more preferably 15 to 35% by mass.

The content of hydroxyl group-containing (meth)acrylate in the monomer component is determined from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. The amount is preferably 0.3 to 25% by weight, more preferably 0.5 to 20% by weight, and even more preferably 0.5 to 15% by weight.

The content of the styrene monomer in the monomer component is preferably 5% from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. ~55% by weight, more preferably 10~50% by weight.

The content of the ultraviolet stable monomer in the monomer component is preferably from the viewpoint of improving image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability and continuous ejection stability, as well as imparting weather resistance. The amount is 1 to 10% by weight, more preferably 2 to 5% by weight. In addition, when the emulsion particles are formed of a plurality of resin layers, from the viewpoint of improving weather resistance, it is preferable that at least the outermost layer of the resin layers contains an ultraviolet stable monomer.

The monomer component may contain a carboxyl group-containing monomer such as (meth)acrylic acid, but from the viewpoint of improving image uniformity and continuous ejection stability, the content of the carboxyl group-containing monomer in the monomer component is preferably 3% by mass or less, more preferably 1% by mass or less, and its lower limit is 0% by mass.

As a method for emulsion polymerization of monomer components, for example, an aqueous medium containing a water-soluble organic solvent such as a lower alcohol such as methanol and water, an emulsifier is dissolved in a medium such as water, and the monomer components and polymerization are initiated under stirring. Examples include a method in which a monomer component is dropped into water or an aqueous medium that has been emulsified in advance using an emulsifier and water, but the present invention is not limited to such methods. . Note that the amount of the medium may be appropriately set in consideration of the amount of nonvolatile components contained in the resulting resin emulsion. The medium may be charged to the reaction vessel in advance or may be used as a pre-emulsion. Further, the medium may be used, if necessary, when monomer components are emulsion polymerized to produce a resin emulsion.

When emulsion polymerizing monomer components, emulsion polymerization may be performed after mixing the monomer components, emulsifier, and medium, or emulsion polymerization may be performed after stirring the monomer components, emulsifier, and medium to prepare a pre-emulsion. Alternatively, emulsion polymerization may be performed by mixing at least one of the monomer components, the emulsifier, and the medium with the remaining preemulsion. The monomer component, emulsifier, and medium may be added all at once, added in portions, or added dropwise continuously.

When forming an outer layer on the emulsion particles contained in the resin emulsion obtained above, the outer layer is formed on the emulsion particles by emulsion polymerizing the monomer components in the resin emulsion in the same manner as above. can be formed. Further, when forming an outer layer on the emulsion particles on which the outer layer has been formed, the outer layer may be further formed on the emulsion particles by emulsion polymerizing the monomer components in the resin emulsion in the same manner as described above. I can do it. As described above, a resin emulsion containing emulsion particles having a multilayer structure can be prepared by the multistage emulsion polymerization method.

Examples of emulsifiers include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, polymer emulsifiers, etc. These emulsifiers may be used alone, or two or more types may be used in combination.

Examples of anionic emulsifiers include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate, sodium dodecyl sulfonate, and sodium alkyl diphenyl ether disulfonate; ammonium dodecylbenzene sulfonate, sodium dodecyl naphthalene sulfonate, etc. alkylaryl sulfonate salt; polyoxyethylene alkyl sulfonate salt; polyoxyethylene alkyl sulfate salt; polyoxyethylene alkylaryl sulfate salt; dialkyl sulfosuccinate; aryl sulfonic acid-formalin condensate; ammonium laurylate, sodium stearate, etc. Fatty acid salt; bis(polyoxyethylene polycyclic phenyl ether) methacrylate sulfonate salt, propenyl-alkyl sulfosuccinate salt, (meth)acrylic acid polyoxyethylene sulfonate salt, (meth)acrylic acid polyoxyethylene phosphonate salt, allyl Allyl group-containing sulfate esters or their salts such as oxymethylalkyloxypolyoxyethylene sulfonate salts; polyoxyethylene alkylphenyl ether sulfate salts, allyloxymethylalkoxyethyl polyoxyethylene sulfate ester salts, polyoxyalkylene alkenyl ethers Examples include ammonium sulfate salts, but the present invention is not limited to such examples.

Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, condensates of polyethylene glycol and polypropylene glycol, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, ethylene oxide and aliphatic Examples include condensates with amines, allyloxymethylalkoxyethylhydroxypolyoxyethylene, and polyoxyalkylene alkenyl ethers, but the present invention is not limited to these examples.

Examples of the cationic emulsifier include alkyl ammonium salts such as dodecylammonium chloride, but the present invention is not limited to such examples.

Examples of amphoteric emulsifiers include betaine ester emulsifiers, but the present invention is not limited to these examples.

Examples of polymer emulsifiers include poly(meth)acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinylpyrrolidone; polyhydroxyalkyl (meth)acrylates such as polyhydroxyethyl acrylate; Examples include copolymers containing one or more of these as a copolymerization component, but the present invention is not limited to such examples.

In addition, from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability, emulsifiers having polymerizable groups, that is, so-called reactive Emulsifiers are preferred, and from the viewpoint of environmental protection, non-nonylphenyl emulsifiers are preferred.

Examples of the reactive emulsifier include propenyl-alkyl sulfosuccinate salts, (meth)acrylic acid polyoxyethylene sulfonate salts, polyoxyethylene alkyl propenyl phenyl ether ammonium sulfate [for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon HS-10, Aqualon BC-10, etc.], allyloxymethylalkyloxypolyoxyethylene sulfonate salts (for example, Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon KH-10, etc.), allyloxymethylnonylphenoxy Ethylhydroxypolyoxyethylene sulfonate salts (for example, manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasorp SE-10, etc.), allyloxymethylalkoxyethylhydroxypolyoxyethylene sulfate salts (for example, manufactured by ADEKA Co., Ltd., product name: ADEKA Reasoap SE-10), Product name: Adekaria Soap SR-10, SR-20, SR-30, etc.], Bis(polyoxyethylene polycyclic phenyl ether) methacrylated sulfonate salt [For example, manufactured by Nippon Nyukazai Co., Ltd., product name: Antox MS -60, etc.], allyloxymethylalkoxyethylhydroxypolyoxyethylene [for example, manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap ER-10, ER-20, ER-30, ER-40, etc.], polyoxyethylene Alkyl propenyl phenyl ether [for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Aqualon RN-20], allyloxymethylnonyl phenoxyethyl hydroxypolyoxyethylene [for example, manufactured by ADEKA Co., Ltd., trade name: Adecaria] Soap NE-10, NE-20, NE-30, etc.], but the present invention is not limited to these examples. These reactive emulsifiers may be used alone or in combination of two or more.

The amount of emulsifier per 100 parts by mass of monomer components is preferably 0.01 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, from the viewpoint of improving polymerization stability. From the viewpoint of improving image uniformity and continuous ejection stability, the amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less.

It is preferable to use a polymerization initiator when polymerizing the monomer components. Examples of the polymerization initiator include azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), and 2,2-azobis( Azo compounds such as 2-diaminopropane) hydrochloride, 4,4-azobis(4-cyanovaleric acid), and 2,2-azobis(2-methylpropionamidine); persulfates such as potassium persulfate; hydrogen peroxide , benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, ammonium peroxide, and the like, but the present invention is not limited to these examples. These polymerization initiators may be used alone or in combination of two or more.

The amount of polymerization initiator per 100 parts by mass of monomer components is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass, from the viewpoint of increasing the polymerization rate and reducing the residual amount of unreacted monomer components. The above content is more preferably 0.1 part by mass or more, from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. Preferably it is 1 part by mass or less, more preferably 0.8 part by mass or less, still more preferably 0.5 part by mass or less.

The method of adding the polymerization initiator is not particularly limited. Examples of the addition method include batch charging, divided charging, continuous dropping, and the like. Moreover, from the viewpoint of bringing the timing of completion of the polymerization reaction earlier, a portion of the polymerization initiator may be added before or after the addition of monomer components into the reaction system is completed.

In addition, in order to accelerate the decomposition of the polymerization initiator, an appropriate amount of a decomposing agent for the polymerization initiator, such as a reducing agent such as sodium bisulfite or a transition metal salt such as ferrous sulfate, may be added to the reaction system. Good too.

Further, in order to adjust the weight average molecular weight of the resin constituting the emulsion particles, a chain transfer agent can be used in the monomer component. When a chain transfer agent is used as a monomer component, it is generally possible to lower the molecular weight of the resin constituting the emulsion particles, compared to when a chain transfer agent is not used as a monomer component. Examples of chain transfer agents include 2-ethylhexyl thioglycolate, tert-dodecylmercaptan, n-octylmercaptan, n-dodecylmercaptan, mercaptoacetic acid, β-mercaptopropionic acid, 2-mercaptoethanol, α-methylstyrene, α -methylstyrene dimer, etc., but the present invention is not limited to such examples. These chain transfer agents may be used alone or in combination of two or more. The amount of chain transfer agent per 100 parts by mass of monomer components is preferably 0.01 to 10 parts by mass from the viewpoint of adjusting the weight average molecular weight of the resin constituting the emulsion particles.

If necessary, additives such as a pH buffer, a chelating agent, and a film-forming aid may be added to the reaction system when polymerizing the monomer components. The amount of additive cannot be determined unconditionally since it varies depending on the type of additive. Usually, the amount of additive per 100 parts by weight of monomer components is preferably about 0.01 to 5 parts by weight, more preferably about 0.1 to 3 parts by weight.

The atmosphere during emulsion polymerization of monomer components is not particularly limited, but from the viewpoint of increasing the efficiency of the polymerization reaction, an inert gas such as nitrogen gas is preferable.

The polymerization temperature during emulsion polymerization of monomer components is not particularly limited, but is usually preferably 10 to 100°C, more preferably 40 to 95°C, and even more preferably 50 to 60°C. The polymerization temperature may be constant or may be changed during the polymerization reaction.

The polymerization time for emulsion polymerization of the monomer components is not particularly limited and may be appropriately set depending on the progress of the polymerization reaction, but is usually about 2 to 8 hours.

In addition, when carrying out emulsion polymerization of a monomer component, some or all of the acidic groups which the obtained polymer has may be neutralized with a neutralizing agent. The neutralizing agent may be used after adding the monomer component in the final stage, for example, it may be used between the first stage polymerization reaction and the second stage polymerization reaction, or it may be used during the initial emulsion polymerization reaction. May be used at the end of the

Examples of neutralizing agents include hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide; carbonates of alkali metals and alkaline earth metals such as calcium carbonate; organic amines such as ammonia and monomethylamine; Examples include alkaline substances, but the present invention is not limited to such examples. Among these neutralizing agents, from the viewpoint of obtaining a water-based ink that is comprehensively superior in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability, volatile agents such as ammonia are recommended. Preferred is an alkaline substance having The neutralizing agent may be used in the form of an aqueous solution.

In addition, when emulsion polymerizing monomer components, silane coupling agents are used to obtain water-based inks that are comprehensively superior in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability. may be used in appropriate amounts. Examples of the silane coupling agent include silane coupling agents having polymerizable unsaturated bonds such as (meth)acryloyl groups, vinyl groups, allyl groups, and propenyl groups, but the present invention is not limited to such examples. It is not limited.

By emulsion polymerizing the monomer components as described above, a resin emulsion containing emulsion particles can be obtained. The polymer constituting the emulsion particles may have a crosslinked structure.

The emulsion particles contained in the resin emulsion may have a single resin layer prepared by one-stage emulsion polymerization, or may have a plurality of resin layers prepared by multi-stage emulsion polymerization. Good too. Emulsion particles having a single resin layer can be prepared by emulsion polymerization of the monomer components. In addition, emulsion particles having a plurality of resin layers can be obtained by emulsion polymerizing the monomer components forming the inner layer using the same polymerization method and polymerization conditions as when emulsion polymerizing the monomer components described above. It can be prepared by multistage emulsion polymerization in which the monomer components forming the outer layer are emulsion polymerized below. When forming the outer layer on the emulsion particles, the monomer component for forming the outer layer is emulsion polymerized after the polymerization reaction rate reaches 90% or more, preferably 95% or more when producing the emulsion particles constituting the inner layer. This is preferable from the viewpoint of forming a layer-separated structure of an inner layer and an outer layer within the emulsion particles.

The number of resin layers constituting the emulsion particles is preferably 1 from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. ~5 layers, more preferably 1 to 3 layers, still more preferably 2 or 3 layers, even more preferably 2 layers. Among these emulsion particles, it is preferable to have a plurality of resin layers from the viewpoint of improving adhesiveness to the base material. Note that when the emulsion particles have a plurality of resin layers, the boundaries between each resin layer do not necessarily have to be clear, and adjacent resin layers may be mixed with each other.

Emulsion particles having multiple resin layers constitute emulsion particles from the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability. It is preferable to have a resin layer with the highest glass transition temperature among the resin layers inside the outermost layer.

In emulsion particles having two resin layers, an inner layer and an outer layer, the mass ratio of the resin layer forming the inner layer to the resin layer forming the outer layer (resin layer forming the inner layer/resin layer forming the outer layer) From the viewpoint of obtaining a water-based ink that is comprehensively excellent in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability, the resin layer (resin layer) is preferably 10/90 to 10/90. The ratio is 90/10, more preferably 20/80 to 80/20, even more preferably 30/70 to 70/30, even more preferably 40/60 to 60/40. Emulsion particles that have three resin layers: an inner layer, an intermediate layer, and an outer layer are water-based inks that are comprehensively superior in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability. From the viewpoint of obtaining the desired properties, the content of the resin layer constituting the inner layer is 10 to 40% by mass, the content of the resin layer constituting the intermediate layer is 20 to 60% by mass, and the content of the resin layer constituting the intermediate layer is 20 to 60% by mass. The content of the resin layer is preferably 20 to 60% by mass.

In emulsion particles having a single resin layer, the glass transition temperature of the resin layer is an aqueous one with comprehensively excellent image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. From the viewpoint of obtaining ink, the temperature is preferably 0 to 50°C, more preferably 5 to 45°C, and still more preferably 10 to 40°C. With emulsion particles having two resin layers, an inner layer and an outer layer, the objective is to obtain a water-based ink that is comprehensively superior in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. Therefore, the glass transition temperature of the resin layer constituting the inner layer is preferably 60 to 120 °C, more preferably 70 to 110 °C, and even more preferably 80 to 100 °C, and the glass transition temperature of the resin layer constituting the outer layer is The glass transition temperature is preferably -45 to 20°C, more preferably -40 to 15°C, even more preferably -35 to 10°C. In addition, the glass transition temperature of the entire emulsion particle having multiple resin layers yields a water-based ink that is comprehensively superior in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability. From this point of view, the temperature is preferably 0 to 50°C, more preferably 5 to 45°C, and still more preferably 10 to 40°C. The glass transition temperature of the resin layer constituting the emulsion particles can be easily adjusted by adjusting the type and amount of monomer used in the monomer component.

In this specification, the glass transition temperature (Tg) of the resin layer constituting the emulsion particles is expressed by the formula:
1/Tg=Σ(Wm/Tgm)/100
[In the formula, Wm indicates the content (mass%) of monomer m in the monomer components constituting the resin layer, and Tgm indicates the glass transition temperature (absolute temperature: K) of the homopolymer of monomer m.]
It means the temperature determined based on the Fox equation expressed by

In this specification, unless otherwise specified, the glass transition temperature of the polymer of the resin layer constituting the emulsion particles means the glass transition temperature determined based on the Fox equation. The glass transition temperature of the entire resin layer constituting the emulsion particles having multiple resin layers is the glass transition temperature of the homopolymer of the monomers used in all the monomer components constituting all the resin layers used during multi-stage emulsion polymerization. The term "transition temperature" refers to the glass transition temperature determined based on the Fox equation. Regarding monomers whose glass transition temperature is unknown, such as special monomers and polyfunctional monomers, if the total amount of monomers whose glass transition temperature is unknown in the monomer components is 10% by mass or less, the glass The glass transition temperature can be determined using only monomers with known transition temperatures. If the total amount of monomers whose glass transition temperature is unknown in the monomer components exceeds 10% by mass, the glass transition temperature of the polymer can be determined by differential scanning calorimetry (DSC), differential calorimetry (DTA), or thermal analysis. It is determined by mechanical analysis (TMA), etc.

The glass transition temperature of the polymer is, for example, 105°C for a homopolymer of methyl methacrylate, -70°C for a homopolymer of 2-ethylhexyl acrylate, -56°C for a homopolymer of n-butyl acrylate, and -56°C for a homopolymer of n-butyl methacrylate. 20°C, 55°C for 2-hydroxyethyl methacrylate homopolymer, 95°C for acrylic acid homopolymer, 130°C for methacrylic acid homopolymer, 100°C for styrene homopolymer, 4-methacryloyloxy-1,2, The temperature is 130°C for the homopolymer of 2,6,6-pentamethylpiperidine and 83°C for the homopolymer of cyclohexyl methacrylate.

The weight average molecular weight of the polymer in the resin layer constituting the emulsion particles is determined from the viewpoint of obtaining a water-based ink that is comprehensively superior in image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. , preferably 100,000 or more, more preferably 300,000 or more, still more preferably 400,000 or more, even more preferably 500,000 or more. The upper limit of the weight average molecular weight of the polymer is not particularly limited because it is difficult to measure the weight average molecular weight if it has a crosslinked structure, but if it does not have a crosslinked structure, it will affect the image uniformity and the substrate material. From the viewpoint of obtaining an aqueous ink that is comprehensively excellent in adhesion to the surface, blocking resistance, viscosity change stability, and continuous ejection stability, it is preferably 4 million or less.

In the present invention, the weight average molecular weight of the polymer in the resin layer constituting the emulsion particles is determined by gel permeation chromatography equipped with an RI detector [manufactured by Tosoh Corporation, product number: HLC-8120GPC, column: TSKgel G-5000HXL] and TSKgel GMHXL-L in series, developing solvent: tetrahydrofuran (THF)] and standard polystyrene F-450 and A-5000 manufactured by Tosoh Corporation. , A-1000 and A-300.

The resin emulsion obtained as described above can be used as the resin emulsion for aqueous ink of the present invention.

In the present invention, a characteristic feature of the present invention is that the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink is 0.01 to 3% by mass. Let's choose one. As mentioned above, all the polymers contained in the resin emulsion for water-based ink include the polymers constituting the emulsion particles contained in the resin emulsion for water-based ink and the polymers other than the polymers contained in the emulsion particles. This is a polymer contained in the resin emulsion for water-based ink.

The aqueous ink of the present invention has a low molecular weight polymer content of 0.01 to 3% by mass with a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for aqueous ink. Excellent in image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability.

The content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink is a value measured based on the following method. That is, first, a calibration curve of retention time and molecular weight is created using the gel permeation chromatography and the standard polystyrene F-450, A-5000, A-1000, and A-300. A gel permeation chromatography chart of the polymer is created using the gel permeation chromatography and polymer. Using the prepared gel permeation chromatography chart of the polymer and the calibration curve, the weight average molecular weight of the polymer is calculated as a standard polystyrene equivalent molecular weight. An embodiment of a gel permeation chromatography chart of the prepared polymer is shown in FIG. FIG. 1 is a graph illustrating one embodiment of a gel permeation chromatography chart for a polymer prepared by gel permeation chromatography. In FIG. 1, the components observed within the weight average molecular weight range of 500 to 4,000,000 are all polymers, and the components observed within the weight average molecular weight range of 500 to 1,000, indicated by arrow X, are low molecular weight polymers.

Next, calculate the peak area of each peak in the gel permeation chromatography chart and use the formula:
[Content of low molecular weight polymer having a weight average molecular weight of 500 to 1000]
= {[Peak area based on a low molecular weight polymer with a weight average molecular weight of 500 to 1000]
÷ [peak area of total polymer]}
×100
The value determined based on is the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers.

In the present invention, when the weight average molecular weight of the low molecular weight polymer is 500 to 1000, if the weight average molecular weight is less than 500, it is considered as a monomer or oligomer, and if the weight average molecular weight exceeds 1000, it is considered as a high molecular weight polymer. This is because it is considered a polymer.

In addition, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all the polymers contained in the resin emulsion for water-based ink is 0.01% by mass or more, preferably 0.01% by mass or more from the viewpoint of improving film forming properties. .3% by mass or more, more preferably 0.8% by mass or more, and has comprehensively excellent image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuous ejection stability. From the viewpoint of yield, it is 3% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass or less, even more preferably 1.5% by mass or less. The content of the low molecular weight polymer having a weight average molecular weight of 500 to 1000 in the total polymer can be easily adjusted by adjusting the type and amount of the monomer used in the monomer component.

The average particle diameter of the emulsion particles is preferably 50 nm or more, more preferably 100 nm or more, from the viewpoint of improving the mechanical stability of the emulsion particles themselves, and has excellent transparency, water resistance, and freeze-thaw repeated stability. From the viewpoint of forming a coating film, the thickness is preferably 400 nm or less, more preferably 350 nm or less. In addition, in the present invention, the average particle diameter of the emulsion particles is obtained by the cumulant method when measured using a particle size distribution analyzer using a dynamic light scattering method [manufactured by Otsuka Electronics Co., Ltd., product number: FPAR-1000]. This is the value.

The non-volatile content of the resin emulsion for water-based ink is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving the productivity of the water-based ink, and from the viewpoint of improving the handleability of the water-based ink, it is preferably is 70% by mass or less, more preferably 60% by mass or less. In the present invention, the non-volatile content of the resin emulsion for water-based ink is calculated by weighing 1 g of the resin emulsion for water-based ink, drying it in a hot air dryer at a temperature of 120°C for 1 hour, and taking the obtained dry residue as the non-volatile content, and formula:
[Nonvolatile content (mass%) of resin emulsion for water-based ink]
= ([mass of dry residue] ÷ [1 g of resin emulsion for water-based ink]) x 100
This is the value calculated based on.

The minimum film-forming temperature of the resin emulsion for water-based ink is preferably 60°C or lower, more preferably 50°C or lower, and even more preferably 40°C or lower, from the viewpoint of improving the adhesion to the base material, and the water resistance and blocking resistance. From the viewpoint of improving properties, the temperature is preferably -5°C or higher, more preferably 5°C or higher, and still more preferably 10°C or higher. The minimum film-forming temperature of the resin emulsion for water-based ink is determined by applying the emulsion to a thickness of 0.2 mm using an applicator on a glass plate placed on a thermal gradient tester, drying it, and applying it to a glass plate placed on a thermal gradient tester to prevent cracks. It means the temperature at which it occurs.

The water-based ink of the present invention contains a resin emulsion for water-based ink and a colorant. Examples of the hue of the colorant include achromatic colors such as white, black, and gray, and chromatic colors such as yellow, magenta, cyan, blue, red, orange, and green; however, the present invention is limited only to such examples. It is not something that will be done.

Colorants include pigments and dyes. Among these, pigments are preferred because they have excellent weather resistance. When using a pigment, the pigment may be used, for example, in the form of a pigment dispersion such as a paste. Examples of pigments include organic pigments and inorganic pigments, and these may be used alone or in combination.

Examples of organic pigments include azo pigments such as benzidine and Hansa yellow, azomethine pigments, methine pigments, anthraquinone pigments, phthalocyanine pigments such as phthalocyanine blue, perinone pigments, perylene pigments, diketopyrrolopyrrole pigments, thioindigo pigments, and iminoisoindoline. Pigments, iminoisoindolinone pigments, quinacridone pigments such as quinacridone red and quinacridone violet, flavanthrone pigments, indanthrone pigments, anthrapyrimidine pigments, carbazole pigments, monoarylide yellow, diarylide yellow, benzimidazolone yellow, trill orange , naphthol orange, quinophthalone pigments, etc., but the present invention is not limited to these examples. These organic pigments may be used alone or in combination of two or more. Preferred organic pigments include, for example, C.I. I. pigment yellow, C. I. pigment red, C. I. pigment orange, C. I. pigment violet, C. I. pigment blue, C. I. Pigment green, etc.

Examples of inorganic pigments include titanium dioxide, antimony trioxide, zinc white, lithopone, lead white, red iron oxide, black iron oxide, iron oxide, chromium oxide green, carbon black, yellow lead, molybdenum red, and ferrocyanide. Pigments with flat shapes such as diiron (Prussian blue), ultramarine, lead chromate, mica, clay, aluminum powder, talc, aluminum silicate, calcium carbonate, magnesium hydroxide, aluminum hydroxide , barium sulfate, magnesium carbonate, and other extender pigments, but the present invention is not limited to these examples. These inorganic pigments may be used alone or in combination of two or more.

The average particle diameter of the pigment is preferably 30 nm or more, more preferably 50 nm or more, from the viewpoint of improving dispersion stability in aqueous ink, and when used as an inkjet aqueous ink, prevents nozzle clogging and improves the nozzle. From the viewpoint of improving the ejection stability of aqueous ink from the head, the thickness is preferably 200 nm or less, more preferably 150 nm or less. The average particle diameter of the pigment means the volume average particle diameter measured using a laser diffraction scattering particle size distribution analyzer [manufactured by Beckman Coulter, product number: LS13320].

Examples of dyes include C.I. I. Solvent Black, C. I. Solvent Red, C. I. Solvent Yellow, C. I. Solvent Blue, C. I. Solvent Green, C. I. Solvent Orange, C. I. Examples include solvent violet, but the present invention is not limited to such examples.

The amount of colorant per 100 parts by mass of non-volatile content of the resin emulsion for water-based ink used in the water-based ink is preferably 50 parts by mass or more, more preferably is 100 parts by mass or more, and from the viewpoint of forming a uniform coating film, is preferably 300 parts by mass or less, more preferably 200 parts by mass or less.

Note that from the viewpoint of improving the dispersibility of the colorant in the aqueous ink, the aqueous ink may contain water or a water-soluble organic solvent. Examples of water-soluble organic solvents include polyhydric alcohols such as diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, 1,3-propanediol, glycerin, dipropylene glycol, and tripropylene glycol; ethylene glycol monomethyl ether, ethylene Ethylene glycol monoethers such as glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether; diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol mono Diethylene glycol monoethers such as isopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, propylene glycol monoisobutyl ether Propylene glycol monoethers such as polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monopropyl ether, polyethylene glycol monoisopropyl ether, polyethylene glycol monobutyl ether, polyethylene glycol monoisobutyl ether; polypropylene glycol monomethyl Examples include polypropylene glycol monoethers such as ether, polypropylene glycol monoethyl ether, polypropylene glycol monopropyl ether, polypropylene glycol monoisopropyl ether, polypropylene glycol monobutyl ether, and polypropylene glycol monoisobutyl ether, but the present invention is limited to such examples only. It is not limited. These water-soluble organic solvents may be used alone or in combination of two or more. Among these water-soluble organic solvents, diethylene glycol, triethylene glycol, propylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether and diethylene glycol monoisobutyl ether are preferred.

The amount of water-soluble organic solvent varies depending on the type and amount of colorant contained in the water-based ink, so it cannot be determined unconditionally. It is preferable to decide as appropriate.

The water-based ink of the present invention contains the resin emulsion for water-based ink and a colorant, but within a range that does not impede the object of the present invention, resin emulsions other than the resin emulsion for water-based ink, water-soluble resins, A resin such as a water-dispersible resin may also be included. In addition, the aqueous ink of the present invention may include, for example, a surfactant, a film forming aid, an ultraviolet absorber, an ultraviolet inhibitor, a filler, a leveling agent, a dispersant, and an additive, within a range that does not impede the purpose of the present invention. Additives such as adhesives, wetting agents, plasticizers, stabilizers, and antioxidants may be included in appropriate amounts.

The content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all the polymers contained in the aqueous ink of the present invention is determined to improve image uniformity, adhesion to the substrate, blocking resistance, viscosity change stability, and continuity. From the viewpoint of improving discharge stability, the content is preferably 0.005 to 3% by mass, more preferably 0.005 to 1.7% by mass. The content of the low molecular weight polymer is determined by sufficiently dissolving the aqueous ink in a developing solvent for gel permeation chromatography such as tetrahydrofuran (THF) and removing undissolved residue. It can be determined in the same manner as the method for measuring the content of low molecular weight polymers in all polymers contained in the resin emulsion. All polymers contained in the water-based ink refer to the polymers contained in the water-based ink other than the polymers constituting the emulsion particles contained in the water-based ink and the polymers contained in the emulsion particles. It is.

In the present invention, prints or images having a predetermined pattern can be formed by ejecting the aqueous ink of the present invention onto a recording medium in a predetermined pattern using, for example, an inkjet recording device.

Examples of recording media include paper, paper laminated with resin films such as polyethylene, polypropylene, and polystyrene (coated paper, etc.), metal plates such as aluminum, zinc, and copper, cellulose, polyethylene terephthalate, polyethylene, polystyrene, etc. Examples include resin films such as polypropylene, polycarbonate, polyvinyl acetal, polyvinyl chloride, and acrylic resin, paper with a metal coating, and resin films with a metal coating, but the present invention is not limited to these examples. .

Further, in the present invention, for example, the aqueous ink of the present invention can be printed onto textile products such as fabrics made of natural fibers such as cotton, synthetic fibers such as polyester fibers, acrylic fibers, and polyamide fibers using an inkjet recording device or the like. By doing so, a desired design can be imparted to the textile product.

The aqueous ink of the present invention obtained as described above has excellent overall image uniformity, adhesion to substrates, blocking resistance, viscosity change stability, and continuous ejection stability, so it can be used, for example, in inkjet applications. Inks such as water-based inks, flexographic printing inks, offset printing inks, lithographic printing inks, gravure printing inks, and screen printing inks, among others, can be suitably used as inkjet water-based inks.

Next, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples.

Example 1
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. A pre-emulsion for first stage dropping consisting of 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 17 g of 2-ethylhexyl acrylate, and 483 g of styrene was placed in a dropping funnel. 30 g of the prepared monomer components, which is about 2% by mass of the total amount of all monomer components, was added into a flask, the temperature was raised to 80°C while slowly blowing nitrogen gas, and 30 g of a 5% ammonium persulfate aqueous solution was added to polymerize. started. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 236 g of ethylhexyl acrylate, 224 g of methyl methacrylate, 20 g of hydroxyethyl methacrylate and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer [manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-] 87] 20 g of a second-stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300 mesh (JIS mesh, hereinafter the same) wire mesh to obtain a resin emulsion for aqueous ink.

In each Example and each Comparative Example, the pH is a value measured at 25° C. using a pH meter [manufactured by Horiba, Ltd., product number: F-23].

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 200 nm. The glass transition temperature of the inner layer of the emulsion particles was 90°C, the glass transition temperature of the outer layer was -5°C, and the glass transition temperature of the emulsion particles themselves was 35°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.24% by mass.

Example 2
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel were placed 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], 460 g of methyl methacrylate, 20 g of 2-hydroxyethyl methacrylate, and 4- as a UV-stable monomer. A pre-emulsion for the first stage dropping consisting of 20 g of (meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB LA-87] was prepared, of which the total monomer content was 30 g, which is about 2% by mass of the total amount of body components, was added into the flask, the temperature was raised to 80° C. while slowly blowing nitrogen gas, and 30 g of 5% ammonium persulfate aqueous solution was added to start polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 329 g of ethylhexyl acrylate, 131 g of styrene, 20 g of hydroxyethyl methacrylate, and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer [manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87] 20 g of a second stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 210 nm. The glass transition temperature of the inner layer of the emulsion particles was 104°C, the glass transition temperature of the outer layer was -33°C, and the glass transition temperature of the emulsion particles themselves was 20°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.53% by mass.

Example 3
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. A first stage consisting of 169 g of deionized water, 70 g of a 25% aqueous solution of emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 38 g of 2-ethylhexyl acrylate, 300 g of methyl methacrylate, and 162 g of styrene was dropped into a dropping funnel. Prepare a pre-emulsion, add 30 g of it, which is about 2% by mass of the total amount of all monomer components, into a flask, raise the temperature to 80 ° C while gently blowing nitrogen gas, and add 30 g of a 5% ammonium persulfate aqueous solution. was added to initiate polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 238 g of ethylhexyl acrylate, 237 g of methyl methacrylate, 5 g of hydroxyethyl methacrylate and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer (manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87) ] 20 g of a second-stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 210 nm. The glass transition temperature of the inner layer of the emulsion particles was 80°C, the glass transition temperature of the outer layer was -1°C, and the glass transition temperature of the emulsion particles themselves was 30°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.18% by mass.

Example 4
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. In a dropping funnel were placed 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 25 g of 2-ethylhexyl acrylate, 270 g of methyl methacrylate, 200 g of styrene, and 5 g of acrylic acid. A pre-emulsion for first-stage dropping was prepared, and 30 g of it, which is about 2% by mass of the total amount of all monomer components, was added into a flask, heated to 80°C while gently blowing nitrogen gas, and heated to 5% filtration. 30 g of ammonium sulfate aqueous solution was added to start polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 194 g of ethylhexyl acrylate, 66 g of methyl methacrylate, 200 g of styrene, 20 g of hydroxyethyl methacrylate, and as a UV-stable monomer 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., product name: ADEKA STAB] LA-87] 20 g of a second stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 230 nm. The glass transition temperature of the inner layer of the emulsion particles was 87°C, the glass transition temperature of the outer layer was 8°C, and the glass transition temperature of the emulsion particles themselves was 40°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 2.20% by mass.

Example 5
779 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel was placed a pre-emulsion for the first stage dropping consisting of 150 g of deionized water, 100 g of a 25% aqueous solution of emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 17 g of 2-ethylhexyl acrylate, and 483 g of styrene. 30 g of the prepared monomer components, which is about 2% by mass of the total amount of all monomer components, was added into a flask, the temperature was raised to 80°C while slowly blowing nitrogen gas, and 30 g of a 5% ammonium persulfate aqueous solution was added to polymerize. started. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 150 g of deionized water, 100 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 236 g of ethylhexyl acrylate, 224 g of methyl methacrylate, 20 g of hydroxyethyl methacrylate and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer (manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87) ] 20 g of a second-stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 200 nm. The glass transition temperature of the inner layer of the emulsion particles was 90°C, the glass transition temperature of the outer layer was -5°C, and the glass transition temperature of the emulsion particles themselves was 35°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.98% by mass.

Example 6
759 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. A pre-emulsion for the first stage dropping consisting of 182 g of deionized water, 50 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 17 g of 2-ethylhexyl acrylate, and 483 g of styrene was placed in a dropping funnel. 30 g of the prepared monomer components, which is about 2% by mass of the total amount of all monomer components, was added into a flask, the temperature was raised to 80°C while slowly blowing nitrogen gas, and 30 g of a 5% ammonium persulfate aqueous solution was added to polymerize. started. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the completion of the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 182 g of deionized water, 50 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: Adekaria Soap SR-20], and 2- 236 g of ethylhexyl acrylate, 224 g of methyl methacrylate, 20 g of hydroxyethyl methacrylate and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer (manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87) ] 20 g of a second-stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 250 nm. The glass transition temperature of the inner layer of the emulsion particles was 90°C, the glass transition temperature of the outer layer was -5°C, and the glass transition temperature of the emulsion particles themselves was 35°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.09% by mass.

Example 7
751 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser tube. A pre-emulsion for the first stage dropping consisting of 195 g of deionized water, 30 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 17 g of 2-ethylhexyl acrylate, and 483 g of styrene was placed in a dropping funnel. 30 g of the prepared monomer components, which is about 2% by mass of the total amount of all monomer components, was added into a flask, the temperature was raised to 80°C while slowly blowing nitrogen gas, and 30 g of a 5% ammonium persulfate aqueous solution was added to polymerize. started. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After completion of the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 195 g, 30 g of a 25% aqueous solution of emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA RIA SOAP SR-20], and 236 g of 2-ethylhexyl acrylate were added. , 224 g of methyl methacrylate, 20 g of hydroxyethyl methacrylate, and 20 g of 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB LA-87] as a UV-stable monomer. A pre-emulsion for second-stage dropping and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 280 nm. The glass transition temperature of the inner layer of the emulsion particles was 90°C, the glass transition temperature of the outer layer was -5°C, and the glass transition temperature of the emulsion particles themselves was 35°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 0.99% by mass.

Example 8
751 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser tube. A pre-emulsion for first stage dropping was prepared consisting of 195 g of deionized water, 30 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA Reasap SR-20], 150 g of methyl methacrylate, and 350 g of styrene. 30 g, which is about 2% by mass of the total amount of monomer components, was added into the flask, the temperature was raised to 80° C. while slowly blowing nitrogen gas, and 30 g of 5% ammonium persulfate aqueous solution was added to start polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After completion of the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 195 g of deionized water, 30 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: Adekarya Soap SR-20], and 2- 287 g of ethylhexyl acrylate, 188 g of methyl methacrylate, 5 g of hydroxyethyl methacrylate and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine as a UV-stable monomer (manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87) ] 20 g of a second-stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 300 nm. The glass transition temperature of the inner layer of the emulsion particles was 101°C, the glass transition temperature of the outer layer was -20°C, and the glass transition temperature of the emulsion particles themselves was 30°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 0.83% by mass.

Example 9
766 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel were 339 g of deionized water, 140 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], 256 g of 2-ethylhexyl acrylate, 352 g of methyl methacrylate, 352 g of styrene, 20 g of hydroxyethyl methacrylate, and A pre-emulsion for the first drop was prepared containing 20 g of 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB LA-87] as a UV-stable monomer. Then, 30 g, which is about 2% by mass of the total amount of all monomer components, was added into the flask, and the temperature was raised to 80°C while slowly blowing nitrogen gas, and 30 g of a 5% ammonium persulfate aqueous solution was added to cause polymerization. It started. Thereafter, the remainder of the pre-emulsion for dropping and 30 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a one-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 210 nm. The glass transition temperature of the emulsion particles themselves was 35°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 1.27% by mass.

Comparative example 1
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. In a dropping funnel were placed 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: Adekaria Soap SR-20], 10 g of 2-ethylhexyl acrylate, 270 g of methyl methacrylate, 200 g of styrene, and 20 g of acrylic acid. A pre-emulsion for first-stage dropping was prepared, and 30 g of it, which is about 2% by mass of the total amount of all monomer components, was added into a flask, heated to 80°C while gently blowing nitrogen gas, and heated to 5% filtration. 30 g of ammonium sulfate aqueous solution was added to start polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 194 g of ethylhexyl acrylate, 66 g of methyl methacrylate, 200 g of styrene, 20 g of hydroxyethyl methacrylate, and as a UV-stable monomer 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., product name: ADEKA STAB] LA-87] 20 g of a second stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 230 nm. The glass transition temperature of the inner layer of the emulsion particles was 96°C, the glass transition temperature of the outer layer was 8°C, and the glass transition temperature of the emulsion particles themselves was 45°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 3.01% by mass.

Comparative example 2
818 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel were 86 g of deionized water, 200 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], 16 g of 2-ethylhexyl acrylate, 230 g of methyl methacrylate, 234 g of styrene, and 20 g of hydroxyethyl methacrylate. A pre-emulsion for first-stage dropping was prepared, and 30 g of it, which is about 2% by mass of the total amount of all monomer components, was added into a flask, and the temperature was raised to 80°C while gently blowing nitrogen gas, and 5% 30 g of ammonium persulfate aqueous solution was added to initiate polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 86 g of deionized water, 200 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- Two stages consisting of 260 g of ethylhexyl acrylate, 220 g of styrene, and 20 g of 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., trade name: ADEKA STAB LA-87] as a UV-stable monomer. A pre-emulsion for eye dropping and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 200 nm. The glass transition temperature of the inner layer of the emulsion particles was 90°C, the glass transition temperature of the outer layer was -13°C, and the glass transition temperature of the emulsion particles themselves was 30°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 3.05% by mass.

Comparative example 3
767 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel were 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], 8 g of 2-ethylhexyl acrylate, 300 g of methyl methacrylate, 162 g of styrene, and 30 g of hydroxyethyl methacrylate. A pre-emulsion for first-stage dropping was prepared, and 30 g of it, which is about 2% by mass of the total amount of all monomer components, was added into a flask, and the temperature was raised to 80°C while gently blowing nitrogen gas, and 5% 30 g of ammonium persulfate aqueous solution was added to initiate polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 20 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropping, the contents of the flask were maintained at 80°C for 60 minutes, and then 169 g of deionized water, 70 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], and 2- 309 g of ethylhexyl acrylate, 131 g of styrene, 40 g of hydroxyethyl methacrylate, and as a UV-stable monomer 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine [manufactured by ADEKA Co., Ltd., product name: ADEKA STAB LA-87] 20 g of a second stage dropping pre-emulsion and 10 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 60 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 45% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a two-layer structure, and the average particle diameter of the emulsion particles is 45% by mass. was 200 nm. The glass transition temperature of the inner layer of the emulsion particles was 95°C, the glass transition temperature of the outer layer was -28°C, and the glass transition temperature of the emulsion particles themselves was 20°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 3.12% by mass.

Comparative example 4
766 g of deionized water was charged into a flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. Into a dropping funnel were placed 339 g of deionized water, 40 g of a 25% aqueous solution of an emulsifier [manufactured by ADEKA Co., Ltd., trade name: ADEKA REA SOAP SR-20], 72 g of 2-ethylhexyl acrylate, 867 g of styrene, 51 g of acrylic acid, and 10 g of hydroxyethyl methacrylate. A pre-emulsion for first-stage dropping was prepared, and 30 g of it, which is about 2% by mass of the total amount of all monomer components, was added into a flask, and the temperature was raised to 80°C while gently blowing nitrogen gas, and 5% 30 g of ammonium persulfate aqueous solution was added to initiate polymerization. Thereafter, the remainder of the pre-emulsion for dropping and 30 g of a 5% ammonium persulfate aqueous solution were uniformly dropped into the flask over 120 minutes.

After the dropwise addition was completed, the contents of the flask were maintained at 80° C. for 60 minutes, and the pH was adjusted to 9 by adding 25% aqueous ammonia to complete the polymerization. The resulting reaction solution was cooled to room temperature and then filtered through a 300-mesh wire mesh to obtain a resin emulsion for aqueous ink.

The content of nonvolatile matter in the obtained resin emulsion for water-based ink is 40% by mass, and the emulsion particles contained in the resin emulsion for water-based ink have a one-layer structure, and the average particle diameter of the emulsion particles is 40% by mass. was 60 nm. The glass transition temperature of the emulsion particles themselves was 80°C. Furthermore, the content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink was 4.21% by mass.

Next, water-based inks were prepared based on the following method using the resin emulsions for water-based inks obtained in each Example or each Comparative Example.

(1) Preparation of water-based ink While stirring 24 g of the resin emulsion for water-based ink obtained in each Example or each Comparative Example at a rotation speed of 1000 min-1 with a homodisper, 25 g of white paste, 10 g of propylene glycol, diethylene glycol monoisopropyl 15 g of ether, 0.4 g of polyether-modified silicone surfactant [manufactured by Shin-Etsu Chemical Co., Ltd., product number: KF-6011] and ion-exchanged water were added so that the total amount was 100 g, and the mixture was further stirred for 30 minutes. Thereafter, a water-based ink was obtained by filtration with a filter having an average pore size of 3 μm (manufactured by Advantech Co., Ltd., product number: MCP-3-C10S).

The white paste contained 428 g of deionized water, 50 g of dispersant [manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Discoat N-14], 60 g of propylene glycol, titanium oxide [manufactured by Ishihara Sangyo Co., Ltd., product number]. :CR-95, average particle size: 0.28 μm] and 200 g of glass beads (diameter: 1 mm) as a dispersion medium were dispersed with a homodisper at a rotation speed of 3000 min for 120 minutes, and then filtered through a 300 mesh wire mesh. It was prepared by:

(2) Production of inkjet printed matter In air at a temperature of 25 ± 1°C and relative humidity of 30 ± 5%, a print evaluation device [Kyocera Corporation, product number: KJ4B-YH06WST-STDV] equipped with an inkjet print head [manufactured by Kyocera Corporation, product number: KJ4B-YH06WST-STDV] ) manufactured by Genesis] was filled with water-based ink.

Next, in the print evaluation device, the head voltage was set to 26 V, the frequency was set to 4 kHz, the ejected droplet volume was set to 12 pL (picoliter), the head temperature was set to 32°C, the resolution was set to 600 dpi, and the negative pressure was set to -4.0 kPa. It was set to A corona-treated polyester film [manufactured by Futamura Kagaku Co., Ltd., trade name: Taiko Polyester Film FE2001] was used as a recording medium, and it was fixed on a conveyor table so that the longitudinal direction of the corona-treated polyester film and the conveyance direction were the same direction. did. The printing command is transferred to the printing evaluation device, and a solid image is printed using an inkjet recording method using water-based ink on a corona-treated polyester film at a printing rate of 100% (12 pL, 600 x 600 dpi). A test sheet was obtained by drying the corona-treated polyester film for 10 seconds.

The following physical properties were investigated using the aqueous ink obtained in each Example or each Comparative Example and the test sheet obtained above. The results are shown in Table 1.

(1) Viscosity change stability By adding ion-exchanged water when preparing the water-based ink and adjusting the amount of ion-exchanged water, the water-based ink A has a non-volatile content of 28% and the water-based ink has a non-volatile content of 33%. Ink B was prepared. Using a B-type viscometer, the viscosity of each water-based ink was measured at a temperature of 25°C and a rotation speed of 60 rpm, and from the viscosity of water-based ink A and the viscosity of water-based ink B, the formula:
[Viscosity change rate (%)] = {[Viscosity of water-based ink B] ÷ [viscosity of water-based ink A]} x 100
The viscosity change rate was determined based on , and the viscosity change stability was evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
10: Viscosity change rate is less than 160% 9: Viscosity change rate is 160% or more and less than 170% 8: Viscosity change rate is 170% or more and less than 180% 7: Viscosity change rate is 180% or more and less than 190% 6: Viscosity change rate is 190% or more and less than 200% 5: Viscosity change rate is 200% or more and less than 210% 4: Viscosity change rate is 210% or more and less than 220% 3: Viscosity change rate is 220% or more and less than 230% 2: Viscosity change rate is 230% or more % or more and less than 240% 1: Viscosity change rate is 240% or more and less than 250% 0: Viscosity change rate is 250% or more

(2) Image Uniformity The printed surface of the test sheet obtained above was visually observed, and the image uniformity was evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
5: No white streaks or color unevenness observed on the printed surface.
4: White streaks and color unevenness are observed on the printed surface at a rate of less than 5%.
3: White streaks and color unevenness are observed on the printed surface at a rate of 5% or more and less than 10%.
2: White streaks and color unevenness are observed on the printed surface at a rate of 10% or more and less than 15%.
1: White streaks and color unevenness are observed on the printed surface at a rate of 15% or more and less than 20%.
0: White streaks and color unevenness are observed on the printed surface at a rate of 20% or more.

(3) Adhesion The printed image on the test sheet was rubbed with a fingernail, and the adhesion to the substrate was evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
5: Even if the printed image is rubbed with a fingernail, the image does not come off at all.
3: When the printed image is rubbed with a fingernail, the image peels off slightly.
0: When the printed image is rubbed with a fingernail, the image is easily peeled off.

(4) Blocking resistance A polyester film that has not been subjected to corona treatment is placed on the printed surface of the test sheet, and a load of 2 N/cm ² is applied on top of the polyester film in air at 25°C for 1 hour. The polyester film was quickly peeled off, the resistance felt at that time was observed, and the blocking resistance was evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
5: No resistance is felt when the polyester film is peeled off.
3: Some resistance is felt when the polyester film is peeled off.
0: Resistance is clearly felt when the polyester film is peeled off.

(5) Continuous ejection stability Images were printed continuously for one hour using the printing evaluation device, the last printed image was visually observed, and continuous ejection stability was evaluated based on the following evaluation criteria. .
〔Evaluation criteria〕
5: No white streaks or color unevenness are observed in the final printed image.
4: White streaks and color unevenness are observed in the final printed image at a rate of less than 5%.
3: White streaks and color unevenness are observed in the final printed image at a rate of 5% or more and less than 10%.
2: White streaks and color unevenness are observed in the final printed image at a rate of 10% or more and less than 15%.
1: White streaks and color unevenness are observed in the final printed image at a rate of 15% or more and less than 20%.
0: White streaks and color unevenness are observed in the final printed image at a rate of 20% or more.

(6) Comprehensive evaluation The sum of the scores for each test item was used as an index for the comprehensive evaluation.

From the results shown in Table 1, the water-based inks obtained in each example had better viscosity change stability, image uniformity, adhesion, and blocking resistance than the water-based inks obtained in each comparative example. It can be seen that the continuous discharge stability is comprehensively excellent.

The water-based ink of the present invention has excellent overall viscosity change stability, image uniformity, adhesion, anti-blocking property, and continuous ejection stability. Forming desired information such as characters, patterns, colors, etc. on a base material made of materials such as wood boards or leather by inkjet printing, flexographic printing, offset printing, lithographic printing, gravure printing, screen printing, ink ribbon, etc. It can be suitably used in industrial inks such as printing inks.

Claims (11)

A resin emulsion for water-based ink containing emulsion particles formed by emulsion polymerization of monomer components with an emulsifier , the low molecular weight polymer having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink. The content of the emulsifier is 0.01 to 3% by mass, the amount of the emulsifier is 0.01 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the monomer component, and a reactive emulsifier is used as the emulsifier. A resin emulsion for water-based ink that is characterized by: The resin emulsion for aqueous ink according to claim 1, wherein the content of hydroxyl group-containing (meth)acrylate in the monomer component is 0.3 to 25% by mass. The resin emulsion for aqueous ink according to claim 1 or 2, wherein the content of the carboxyl group-containing monomer in the monomer component is 3% by mass or less. The resin emulsion for water-based ink according to any one of claims 1 to 3, wherein the content of alkyl (meth)acrylate in the monomer component is 35 to 85% by mass. The resin emulsion for water-based ink according to any one of claims 1 to 4, wherein the content of alkyl (meth)acrylate whose alkyl group has 1 to 3 carbon atoms in the monomer component is 10 to 60% by mass. The resin emulsion for water-based ink according to any one of claims 1 to 5, wherein the content of alkyl (meth)acrylate whose alkyl group has 4 to 8 carbon atoms in the monomer component is 10 to 40% by mass. The resin emulsion for aqueous ink according to any one of claims 1 to 6, wherein the content of the styrene monomer in the monomer component is 5 to 55% by mass. The resin emulsion for water-based ink according to any one of claims 1 to 7, wherein the content of the ultraviolet stable monomer in the monomer component is 1 to 10% by mass. An aqueous ink comprising the resin emulsion for an aqueous ink according to any one of claims 1 to 8 and a colorant. A method for producing a resin emulsion for an aqueous ink containing emulsion particles by emulsion polymerizing a monomer component with an emulsifier, the amount of the emulsifier being 0.01 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the monomer component. The content of low molecular weight polymers having a weight average molecular weight of 500 to 1000 in all polymers contained in the resin emulsion for water-based ink is adjusted to 0.01 to 3% by mass using a reactive emulsifier as the emulsifier. A method for producing a resin emulsion for water-based ink, characterized by the following. 11. The method for producing a resin emulsion for water-based ink according to claim 10, wherein when emulsion polymerizing the monomer components, some or all of the acidic groups possessed by the resulting polymer are neutralized with a neutralizing agent.

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