Viscosity modifier

Abstract

To provide a viscosity modifier that can be added to a water-based coating to reduce changes in viscosity due to temperature.SOLUTION: The viscosity modifier contains a compound represented by the general formula (1) in the figure. (In the formula: R1 is a hydrogen atom, a methyl group, or an ethyl group; R2O, R3O and R4O are C2-4 oxyalkylene groups; a, b and c are positive numbers satisfying the relationship 15≤a+b+c≤300; and m is 0 or 1)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a viscosity modifier that can reduce temperature-induced changes in viscosity when blended into water-based paints and the like. [Background technology]

[0002] In recent years, the replacement of solvent-based paints with water-based paints has been progressing in order to reduce volatile organic compounds (VOCs). This replacement has caused various problems due to the differences in the properties of solvent-based and water-based paints. For example, in solvent-based paints, the resins used in the paint are mainly homogeneous due to the solvent, whereas in water-based paints, they are often in a non-uniform dispersion system like an emulsion, and the viscosity changes with changes in temperature and humidity, which can cause problems such as sagging when applied by spraying.

[0003] Methods for solving such problems include controlling temperature and humidity, increasing the solid content of the paint, and adding a thickener that improves thixotropy. However, in Japan, the outdoor temperature ranges from 5°C to 35°C, and there are some places where the temperature difference between summer and winter is more than 30°C, so the viscosity changes significantly with temperature changes, making it difficult to control. Even if a thickener that improves thixotropy, such as hydrophobically modified polyether urethane (HEUR) disclosed in Patent Documents 1 to 3, is added, there is an issue that the temperature dependency of the viscosity is not satisfactory, and there is a demand for a paint that can obtain a coating film of the same quality throughout the year. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-063486 A [Patent Document 2] JP 2009-280656 A [Patent Document 3] JP 2013-122011 A Summary of the Invention [Problem to be solved by the invention]

[0005] The thickeners described in Patent Documents 1 to 3 are satisfactory in terms of thickening properties, but are not satisfactory in terms of temperature dependency of viscosity. An object of the present invention is to provide a viscosity adjuster that can reduce the change in viscosity due to temperature by adding it to a water-based paint. [Means for solving the problem]

[0006] As a result of extensive research aimed at solving the above problems, the inventors discovered that the temperature dependence of viscosity is reduced by adding an alkylene oxide adduct of a trihydric alcohol to an aqueous coating composition containing water as the main solvent, and thus completed the present invention.

[0007] That is, the present invention is as follows. [1] A viscosity modifier containing a compound represented by the following general formula (1): [ka] (In the formula, R 1 is a hydrogen atom, a methyl group, or an ethyl group; R 2 O, R 3 O, R 4 O is an oxyalkylene group having 2 to 4 carbon atoms, a, b, and c are positive numbers satisfying the relationship 15≦a+b+c≦300, and m is 0 or 1. [2] The viscosity modifier according to [1], wherein the total proportion of the oxyalkylene groups having 3 carbon atoms and the oxyalkylene groups having 4 carbon atoms is 70 mass% or more, based on the total mass of the oxyalkylene groups in the general formula (1). [3] An aqueous coating composition comprising the viscosity modifier and thickener according to [1] or [2]. [4] The aqueous coating composition according to [3], wherein the thickener is an associative thickener. [5] The aqueous coating composition according to [4], wherein the associative thickener is a hydrophobically modified polyether urethane (HEUR). Effect of the Invention

[0008] Water-based paints to which a viscosity modifier containing a compound represented by the general formula (1) according to the present invention has been added have a reduced temperature dependency of viscosity, and can therefore be used as paints with stable quality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below. The viscosity modifier used in the present invention contains a compound represented by the following general formula (1). [ka] (In the formula, R 1 is a hydrogen atom, a methyl group, or an ethyl group; R 2 O, R 3 O, R 4 O is an oxyalkylene group having 2 to 4 carbon atoms, a, b, and c are positive numbers satisfying the relationship 15≦a+b+c≦300, and m is 0 or 1.

[0010] The compound represented by the general formula (1) is obtained by addition polymerization of an alkylene oxide to a trihydric alcohol such as glycerin, trimethylolpropane, or trimethylolethane in the presence of a catalyst such as potassium hydroxide by a known method, and the addition form may be either random addition or block addition. In some cases, a base-catalyzed rearrangement of an epoxide (e.g., propylene oxide) occurs as a side reaction during the addition polymerization, resulting in a monofunctional polyether having an allyl or propenyl alcohol and a terminal double bond, and these may also be included.

[0011] In addition, in consideration of side reactions, it is preferable to make the number of moles of alkylene oxide added larger than the designed number. The hydroxyl value of the compound represented by the general formula (1) is preferably 10 mgKOH / g or more and 200 mgKOH / g or less, more preferably 15 mgKOH / g or more and 180 mgKOH / g or less, and further preferably 20 mgKOH / g or more and 170 mgKOH / g or less.

[0012] In general formula (1), R2 , R 3 , R 4 represents an alkylene group having 2 to 4 carbon atoms. That is, R 2 O, R 3 O and R 4 O represents at least one of an oxyethylene group, an oxypropylene group, and an oxybutylene group, and from the viewpoint of reducing the temperature dependency of viscosity, the total proportion of the oxyalkylene groups having 3 carbon atoms and the oxyalkylene groups having 4 carbon atoms is preferably 50 mass% or more, more preferably 60 mass% or more, and particularly preferably 70 mass% or more, based on the total mass of the oxyalkylene groups.

[0013] In the general formula (1), a, b, and c each represent an oxyalkylene group R 2 O, R 3 O and R 4 The average number of moles of O added, that is, the total number, is preferably 15 or more and 300 or less, and from the viewpoints of the influence of temperature dependency, solubility in water, and dispersibility, is more preferably 20 or more and 200 or less, and particularly preferably 30 or more and 100 or less.

[0014] The content of the viscosity modifier containing the compound represented by general formula (1) in the water-based paint is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 8 parts by mass, and particularly preferably 0.5 to 3 parts by mass, per 100 parts by mass of the water-based paint in its as-is form.

[0015] The viscosity modifier containing the compound represented by the general formula (1) of the present invention can impart thickening properties to water-based paints by using it in combination with a thickener.

[0016] As thickening agents, for example, natural and semi-synthetic types, such as gellan gum, curdlan, xanthan gum, dextran, cyclodextrin, pullulan, hyaluronic acid, lanthan gum, welan gum, diutan gum, gum arabic, ghatti gum, karaya gum, tragacanth gum, arabinogalactan, quince, guar gum, and guar gum derivatives (cationized guar gum, carboxymethyl-hydroxypropylated guar gum, hydroxypropylated guar gum, etc.) etc.), Aphanothece saccharum polysaccharides, quince seed gum, psyllium seed gum, konjac mannan, tara gum, tamarind gum, starch, roasted bean gum, carrageenan, alginic acid, sodium alginate, propylene glycol alginate, Alcaligenes polysaccharides, agar, starch, sodium starch glycolate, corn starch, furcellan, pectin, albumin, casein, sodium caseinate, ammonium caseinate, Gelatin, collagen, keratin, chitosan, succinoglycan, microcrystalline cellulose, fermented cellulose, methylcellulose (MC), methylhydroxyethylcellulose (MHEC), hydroxypropylcellulose (HPC), methylhydroxypropylcellulose (MHPC), carboxymethylcellulose (CMC), alkali metal salts of carboxymethylcellulose, ethylcellulose, hydroxypropylmethylcellulose (HPMC), hydrophobized hydroxypropylmethylcellulose (HM-HPMC), hydroxyethylmethylcellulose (HEMC), hydroxyethylcellulose (HEC), cationic cellulose, carboxymethylcellulose, starch phosphate ester, sodium starch glycolate, soy protein hydrolysate, collagen hydrolysate, cellulose nanofiber (CNF) prepared by TEMPO oxidation, starch-sodium acrylate graft polymer, etc.

[0017] Inorganic and semi-synthetic thickeners include silica, fumed silica, montmorillonite, beidellite, saponite, stevensite, hectorite, synthetic smectite, trimethylstearyl ammonium bentonite, dimethyl distearyl ammonium bentonite, benzyl dimethylstearyl ammonium bentonite, dimethyl distearyl ammonium hectorite, magnesium aluminum silicate, sodium silicate, and magnesium silicate.

[0018] As for synthetic systems, carboxyvinyl polymers such as polyacrylic acid (CVP), or their microgels, or salts with alkali (sodium polyacrylate, ammonium polyacrylate, polyacrylic alkanolamine, etc.), cross-linked polyacrylic acid, or its alkali salts, copolymers of acrylic acid and long-chain alkyl methacrylate, polyvinylpyrrolidone (PVP), vinylpyrrolidone-eicosene copolymer, polyvinyl methyl ether (PVME), polymethyl vinyl ether-maleic anhydride copolymer, alkyl acrylate-alkyl methacrylate-polyoxyethylene stearyl ether methacrylate copolymer, polydialkyldimethylammonium chloride, polyacrylamide, acrylamide-dialyl Examples of the polyether esters include polyoxyethylene distearate, polyoxyethylene dioleate methyl glucoside, polyoxyethylene pentaerythritol tetrastearate, polyoxyethylene sorbitan triisostearate, and other polyether esters; polyvinyl alcohol, polyethylene oxide, ethylene oxide-propylene oxide block copolymers, coconut oil fatty acid diethanolamide, coconut oil fatty acid monoethanolamide, lauric acid diethanolamide, (acrylic acid / perfluorohexylethyl acrylate) crosspolymer, and hydrophobically modified ethoxylated urethane (hereinafter referred to as HEUR).

[0019] Among the above thickeners, HEUR is suitable because it has high water resistance, little change in viscosity with pH, ​​and sufficient thixotropy, which are required for paints. HEUR is a hydrophobically modified polyether urethane made by reacting a water-soluble polyether polyol and a compound having a hydrophobic group and an active hydrogen atom in the molecule with a polyisocyanate compound, and is an association type thickener that exerts its effect by adsorbing to resin particles via the hydrophobic groups at both ends and by forming a network structure through the association of the hydrophobic groups with each other.

[0020] The water-soluble polyether polyol refers to a polymer produced using ethylene oxide, propylene oxide, or butylene oxide and having two or more functional groups, and examples thereof include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol, polytetramethylene ether glycol, neopentyl glycol, 1,6-hexanediol, polyoxyalkylene glycerin ether, polyoxyalkylene trimethylolpropane, polyoxyalkylene triethanolamine, polyoxyalkylene pentaerythritol, polyoxyalkylene ethylenediamine, polyoxyalkylene diethylenetriamine, polyoxyalkylene sorbitol, polyoxyalkylene sucrose, polyoxyalkylene cyclohexane dimethanol, and polyoxyalkylene bisphenol A ether.

[0021] The compound having a hydrophobic group and an active hydrogen atom is preferably a monovalent nonionic surfactant or a higher alcohol, and is preferably a polyether of a linear, branched or secondary monovalent alcohol. For example, polyoxyalkylene 2-ethylhexyl ether, polyoxyalkylene octyl ether, polyoxyalkylene isooctyl ether, polyoxyalkylene lauryl ether, polyoxyalkylene isotridecanol, polyoxyalkylene myristyl ether, polyoxyalkylene cetyl ether, polyoxyalkylene stearyl ether, polyoxyalkylene isostearyl ether, polyoxyalkylene oleyl ether, polyoxyalkylene behenyl ether, polyoxyalkylene octyldodecyl (Guerbet type) ether, polyoxyalkylene distyrenated phenyl ether, polyoxyalkylene polybenzyl phenyl ether, polyoxyalkylene alkenyl ether, etc. can be mentioned. Examples of higher alcohols include hexyl alcohol, 2-ethylhexanol, isotridecanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, hexyldecanol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, behenyl alcohol, octyldodecanol, and decyltetradecanol.

[0022] The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule, and examples thereof include aliphatic diisocyanates, aromatic diisocyanates, and alicyclic diisocyanates.

[0023] Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, 2-methylpentane-1,5-diylbisisocyanate, 1,6-diisocyanato-2,2,4-trimethylhexane, hexamethylene diisocyanate, undecane-1,11-diyl diisocyanate, and octamethylene diisocyanate.

[0024] Examples of aromatic diisocyanates include monomeric diphenylmethane diisocyanate (monomeric MDI), polymeric diphenylmethane diisocyanate (polymeric MDI), 2,4-tolylene diisocyanate (2,4TDI), 2,6-tolylene diisocyanate (2,6TDI), naphthalene diisocyanate, p-phenylene diisocyanate, and m-xylylene diisocyanate.

[0025] Examples of alicyclic diisocyanates include isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (HMDI), hydrogenated xylylene diisocyanate (H6XDI), norbornane diisocyanate (NBDI), 1-methylcyclohexane-2,4-diyl diisocyanate (hydrogenated TDI), and cyclohexane-1,3-diisocyanate.

[0026] Moreover, these polyisocyanate compounds may be used in the form of a dimer or trimer (isocyanurate bond), or may be reacted with water or an amine to be used as a biuret.

[0027] The method for producing HEUR is the same as that for the reaction of a normal polyether with an isocyanate, for example, by heating the mixture at 80 to 120° C. for 1 to 3 hours for reaction, and then dispersing the mixture in water.

[0028] The amount of thickener to be used is usually 0.1 to 30 parts by mass, preferably 0.2 to 20 parts by mass, and more preferably 0.3 to 10 parts by mass, per 100 parts by mass of the solids content of the aqueous coating composition.

[0029] Other materials that can be used in water-based paints include base materials such as resin emulsions, monomer emulsions, resin solutions, film-forming agents, defoamers, surfactants, solvents, plasticizers, pigments, antibacterial agents, and preservatives.

[0030] Resin emulsions include polyvinyl acetate resin emulsions, poly(meth)acrylic esters, copolymer resin emulsions thereof, versatic acid vinyl ester resin emulsions, styrene resin emulsions, styrene-butadiene resin emulsions, styrene-acrylic resin emulsions, styrene-maleic anhydride resin emulsions, acrylonitrile-butadiene resin emulsions, ethylene-vinyl acetate resin emulsions, ethylene-vinyl alcohol resin emulsions, ethylene-(meth)acrylic acid resin emulsions, ethylene-(meth)acrylic acid ester-maleic anhydride resin emulsions, oxidized polyethylene resin emulsions, oxidized polypropylene resin emulsions, maleic anhydride modified polyethylene resin emulsions, maleic anhydride modified polypropylene resin emulsions, maleic anhydride modified ethylene-propylene resin emulsions, maleic anhydride modified ethylene-butene-propylene resin emulsions, maleic anhydride modified ethylene-butene resin emulsions, maleic anhydride modified polybutadiene emulsions. ion, chlorinated polyethylene resin emulsion, chlorinated polypropylene resin emulsion, epoxy resin emulsion, urethane resin emulsion, urethane acrylic resin emulsion, polyester resin emulsion, alkyd resin emulsion, amino alkyd resin emulsion, polyvinyl chloride resin emulsion, rosin emulsion, rosin ester emulsion, petroleum resin emulsion, urea resin (urea resin) emulsion, melamine resin emulsion, phenol resin emulsion, resorcinol resin emulsion, silicone resin emulsion, fluorine resin emulsion, terpene resin emulsion, terpene phenol resin emulsion, polylactic acid resin emulsion, paraffin wax emulsion, microcrystalline wax emulsion, FT wax emulsion, carnauba wax emulsion, rice wax emulsion, montan wax emulsion, candelilla wax emulsion, beeswax emulsion, shellac emulsion, amide wax emulsion, and the like.Examples of the resin solution include water-soluble phenol solutions, polyvinyl alcohol, poly(meth)acrylic acid, alkali metal salts of poly(meth)acrylic acid, alkali metal salts, amine salts, and ammonium salts of isobutylene-maleic anhydride copolymer resins.

[0031] Examples of monomer emulsions include emulsions in which meth(acrylic acid) esters are dispersed for the purpose of curing with UV, etc. Examples of monomers for UV curing include monofunctional acrylate monomers such as β-carboxyethyl acrylate, isobornyl acrylate, and ethoxylated phenyl acrylate, bifunctional acrylate monomers such as dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, polypropylene oxide modified neopentyl glycol diacrylate, polyoxyethylene modified bisphenol A diacrylate, polyethylene glycol modified diacrylate, tricyclodecane dimethanol diacrylate, and trifunctional acrylate monomers such as trimethylol diacrylate. Examples of the acrylate monomer having 4 or more functional groups include pentaerythritol (tri / tetra)acrylate, pentaerythritol alkoxytetraacrylate, pentaerythritol ethoxytetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, and examples of the methacrylate monomer include isobornyl methacrylate, polyethylene glycol dimethacrylate, trimethylpropane trimethacrylate, etc. The blending amount of the resin emulsion, monomer emulsion, and resin solution is usually 60 parts by mass or more and 99 parts by mass or less as solid content relative to 100 parts by mass of the solid content of the water-based paint composition, but is preferably 70 parts by mass or more and 99 parts by mass or less, and more preferably 80 parts by mass or more and 99 parts by mass or less.

[0032] Examples of film-forming aids include ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-t-butyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoallyl ether, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monobutyl ether, propylene glycol mono-2-ethylhexanoate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol ethyl methyl ether, and diethylene glycol monobenzyl ether. glycol ethers such as ethylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monobutyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, hexyl diglycol, and acetylene glycol; glycol ether acetates such as ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, and diethylene glycol monoethyl ether acetate; 2,2,4-trimethyl-1,Examples of the compound include pyrrolidone compounds such as 3-pentanediol monoisobutyrate, N-methyl-2-pyrrolidone, N-ethylpyrrolidone, N-propylpyrrolidone, N-isopropylpyrrolidone, N-butylpyrrolidone, N-cyclohexylpyrrolidone, N-octylpyrrolidone, N-phenylpyrrolidone, and vinylpyrrolidone; perfluoroalkyl group-containing compounds such as perfluoroalkylsulfonic acid (PFOS), perfluoroalkylcarboxylic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and perfluorohexanoic acid (PFHxA); and alcohol compounds such as methanol, ethanol, isopropanol, n-butanol, n-hexanol, and benzyl alcohol. The amount of the film-forming aid is usually 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the aqueous coating composition.

[0033] Examples of the defoaming agent include mineral oil-based, alcohol-based, organic compound-based, mineral oil-based, and silicone-based defoaming agents. Examples of the alcohol-based agent include methanol, ethanol, isopropanol, sec-butanol, and n-butanol. Examples of the organic compound-based agent include higher alcohols, hydrocarbon waxes, ethylene oxide of higher alcohols, propylene oxide adducts, polypropylene glycol, and Pluronic (registered trademark) type ethylene oxide adducts, which are mixed and dispersed. Examples of the mineral oil-based agent include those in which paraffin-based and naphthene-based mineral oils are dispersed with a dispersant. Examples of the silicone-based agent include those in which silicone oils and silicone resins are dispersed with a dispersant. Compounds using calcium carbonate and silica powder may also be used, and the amount of the defoaming agent is usually 0.001 to 10 parts by mass relative to 100 parts by mass of the aqueous coating composition, but is preferably 0.005 to 5 parts by mass, and more preferably 0.01 to 1 part by mass.

[0034] In the present invention, a surfactant may be used as a dispersing aid for pigments, etc. In this case, known and publicly used surfactants such as nonionic, anionic, cationic, and amphoteric surfactants may be used according to the purpose, but it is desirable to select the type and amount of surfactant that does not inhibit the development of the effects of the invention. Examples of nonionic surfactants include polyoxyethylene 2-ethyl-hexyl ether, polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene dodecyl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene isostearyl ether, polyoxyethylene behenyl ether, polyoxyethylene octyldodecyl (Guerbet type) ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene β-naphthyl ether, polyoxyethylene hydrogenated castor oil ether, polyethylene glycol monoalkyl fatty acid ester, polyethylene glycol dialkyl fatty acid ester, and polyoxyethylene sorbitan monolaurate, but in order to obtain a stable polymer, an anionic surfactant may be used in addition to the nonionic surfactant.Anionic surfactants include sodium salt of semi-hardened beef tallow fatty acid, sodium salt of stearate, potassium salt of oleate, sodium salt of gum rosin-based disproportionated rosin, dipotassium salt of alkenyl succinate, sodium salt of dodecyl sulfate, sodium salt of polyoxyethylene alkyl (C12, C13) ether sulfate, ammonium salt of polyoxyethylene dodecyl sulfate, sodium salt of dodecylbenzenesulfonate, and cationic surfactants include behentrimonium chloride, stearamidoethyl dimethylamine, cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, tri(polyoxyethylene)stearylammonium chloride, and salt. Examples of surfactants include stearyl trimethyl ammonium chloride, lauryl trimethyl ammonium chloride, and ambidextrous surfactants include lauryl dimethyl aminoacetate betaine, coconut oil fatty acid amidopropyl betaine solution, N-lauroyl-N'-carboxymethyl-N'-hydroxyethyl ethylenediamine sodium, coconut oil alkyl dimethylamine oxide, and lauryl dimethylamine oxide. Examples of reactive surfactants include polyoxyethylene alkenyl phenyl ether, and its sulfate ester salt, sulfosuccinic acid type, alkenyl polyoxyalkylene phosphate ester, sodium p-styrenesulfonate, and polyoxyethylene (meth)acryloyl ether. Furthermore, protective colloids such as polyvinyl alcohol may be used as a substitute for surfactants, and the amount of surfactant blended is usually 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the aqueous coating composition.

[0035] Furthermore, organic solvents can be used to shorten the drying time of water-based paints and improve paint stability. For example, alcohols such as methyl alcohol, ethyl alcohol, denatured ethanol, isopropyl alcohol, normal propyl alcohol, isobutyl alcohol, butyl alcohol, hexanol, 2-ethylhexanol, and benzyl alcohol, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, hydrocarbons such as benzene, toluene, xylene, normal hexane, isohexane, cyclohexane, methylcyclohexane, ethylcyclohexane, normal heptane, volatile oil, mineral spirits, C9 aromatic hydrocarbon mixtures, C10 aromatic hydrocarbon mixtures, naphtha, kerosene, and turpentine. Examples of solvents include ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, normal propyl acetate, and isopentyl acetate; ether-based solvents such as 1,3-dioxolane, 1,4-dioxane, diethyl ether, and tetrahydrofuran; chlorine-based solvents such as methylene chloride, trichloroethylene, perchloroethylene, and chlorobenzene; and vegetable oils such as soybean oil, rapeseed oil, linseed oil, tung oil, and castor oil. The amount of the solvent to be blended is usually 0.1 to 50 parts by mass, but preferably 1 to 40 parts by mass, and more preferably 2 to 30 parts by mass, per 100 parts by mass of the aqueous coating composition.

[0036] Examples of the plasticizer that can be used include citric acid esters such as acetyl tributyl citrate, phosphate esters such as tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, and tributoxyethyl phosphate, aliphatic dibasic acid esters such as dibutyl adipate, di-2-ethylhexyl adipate, di-n-alkyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, and di-2-ethylhexyl sebacate, isobutyl ester derivatives of pentadiol, and chlorinated paraffin. The amount of the plasticizer to be added is usually 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the aqueous coating composition as is.

[0037] Pigments include inorganic and organic pigments. Inorganic pigments include titanium dioxide, calcium carbonate, clay, talc, precipitated barium sulfate and baryte powder, white carbon, pearl pigments (bismuth oxychloride, basic lead carbonate, titanium oxide-coated mica, etc.), metal powder pigments (aluminum powder, copper powder, brass powder, gold powder, lead powder, tin powder, zinc powder, nickel powder, stainless steel powder, etc.), zinc oxide, zinc sulfide, cadmium pigments, yellow lead, lead pigments, phosphate pigments, chromate pigments, molybdate pigments, micaceous iron oxide, zinc powder, cuprous oxide, carbon black, iron oxide (iron black), yellow iron oxide, red iron oxide (synthetic or natural), brown iron oxide, iron blue, ultramarine, chromium oxide, and composite oxide pigments (titanium-antimony-nickel composite oxide, iron-zinc composite oxide, titanium-barium-nickel composite oxide, cobalt-aluminum-chromium composite oxide, etc.).

[0038] Organic pigments can be broadly divided into azo pigments and polycyclic pigments based on their chemical structure. Azo pigments include soluble azo pigments such as Lake Red C, Risol Red BA, Risol Red CA, Risol Red SR, Brilliant Carmine 6B, Permanent Red 2B, Bon Red, Bordeaux 10B, and Pigment Rubin G. Insoluble azo pigments include Para Red, Naphthol Orange, Brilliant Fast Scarlet, Naphthol Red FRR, Naphthol Red M, Fast Yellow G, Benzimidazolone Yellow H3G, Disazo Yellow HR, and Balkan Orange. Condensed azo pigments include Condensed Azo Yellow 166 and Condensed Azo Red BR. Examples of polycyclic pigments include phthalocyanine pigments such as metal-free phthalocyanine blue, phthalocyanine blue (α type), and highly chlorinated phthalocyanine green, and condensed polycyclic pigments such as anzanthrone orange, indigo blue, perinone orange, quinophthalone yellow, dioxazine violet 37, unsubstituted quinacridone red (γ type), quinacridone magenta, isoindolinone yellow G, nickel complex orange, isoindoline yellow 139, and diketopyrrolopyrrole red 255. Other pigments include fluorescent pigments, aniline black, and alkali blue toner. The amount of pigment is usually 0.1 to 50 parts by mass relative to 100 parts by mass of the aqueous coating composition, but is preferably 3 to 30 parts by mass, and more preferably 5 to 20 parts by mass.

[0039] Antibacterial and preservative agents include parabens (hydroxybenzoic acid esters) such as methylparaben, ethylparaben, propylparaben, and butylparaben, phenoxyethanol, 1,2-alkanediols such as 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol, salicylic acid, sodium benzoate, isothiazolinone derivatives such as methylisothiazolinone (MIT), chloromethylisothiazolinone (CMIT), octylisothiazolinone (OIT), dichlorooctylisothiazolinone (DCOIT), and benzisothiazolinone (BIT), dehydroacetic acid and its salts, trichlorocarbanide, zinc pyrithione, and cetylbichloride. Examples of such additives include lysinium, benzalkonium chloride, benzethonium chloride, bronopol, sorbic acid, chlorhexidine, chlorhexidine gluconate, halocarban, hexachlorophene, hinokitiol, phenol, other phenols such as isopropylmethylphenol (thymol), cresol, parachlorophenol, phenylphenol, and sodium phenylphenol, antibacterial zeolite, and silver ions. The amount of such additives to be added is usually 0.01 to 0.3 parts by mass, preferably 0.02 to 0.2 parts by mass, and more preferably 0.05 to 0.1 parts by mass, per 100 parts by mass of the aqueous paint composition as is.

[0040] The water-based coating composition can be prepared by mixing the above-mentioned raw materials using a known device and a known method. Examples of the stirrer include a magnetic stirrer, a mechanical stirrer, a homogenizer, a high-pressure homogenizer, a disperser, an ultrasonic disperser, a bead mill, a ball mill, a three-roll mill, a milder, circulation by a pump, centrifugal stirring, etc., and the water-based coating composition can be obtained by charging a resin emulsion, a monomer emulsion, a resin solution, a viscosity adjuster, a film-forming assistant, an antifoaming agent, a surfactant, water, a solvent, a plasticizer, a pigment, an antibacterial agent, an antiseptic agent, etc., and stirring and circulating the mixture. EXAMPLES

[0041] The present invention will now be described with reference to examples, but the present invention is not limited to these examples. In the following, "parts" refers to "parts by mass" unless otherwise specified.

[0042] (Synthesis Example 1: Synthesis of thickener) In a 1-liter four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 264.7 parts of polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., product name: PEG-10000, number average molecular weight 11,000) and 27.8 parts of polyoxyethylene lauryl ether (ethylene oxide 12 mole adduct) (manufactured by Toho Chemical Industry Co., Ltd., product name: Pegnol (registered trademark) L-12S) were charged, and the mixture was dehydrated at 120 ° C. under a reduced pressure of 10 mmHg or less for 4 hours to reduce the water content of the system to 100 ppm. Next, while maintaining the temperature at 120 ° C., 0.0015 parts of dibutyltin laurate (manufactured by Tokyo Fine Chemical Co., Ltd., product name: EMBILIZER (registered trademark) L-101) and then 7.4 parts of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name HDI) were added, and the reaction was carried out while stirring for 1.5 hours. After that, after confirming that the peak of the isocyanate group derived from HDI disappeared by FT-IR, 700 parts of ion-exchanged water was gradually added, and the mixture was then aged at 80°C for 1 hour, cooled to 30°C, and 0.5 parts of a preservative (Shoei Chemical Co., Ltd.: Levanax BX-150) was added and stirred for 10 minutes to obtain thickener A-1.

[0043] (Synthesis Example 2: Synthesis of Viscosity Modifier) After thoroughly replacing the atmosphere in a 5L stainless steel pressure-resistant reactor equipped with two drip inlet tubes and a gas inlet / outlet with dry nitrogen gas, 220 parts of glycerin propylene oxide adduct (hydroxyl value: 205 mg KOH / g) and 8 parts of flaky KOH were charged and the temperature of the reactor was raised to 130°C while stirring. While maintaining the temperature at 130°C, 2200 parts of propylene oxide were continuously injected from the drip inlet tube over 8 hours to cause an addition reaction of propylene oxide. While maintaining the temperature at 130°C, 395 parts of ethylene oxide were continuously injected from the drip inlet tube over 2 hours to cause an addition reaction of ethylene oxide. After the reaction was completed, the temperature was lowered to 100°C, neutralization and purification were performed, and a transparent viscous viscosity modifier B-1 was obtained.

[0044] Example 1: Preparation of water-based coating composition For a 500 ml disposable cup, 100 parts of acrylic resin emulsion (manufactured by Japan Coating Resins Co., Ltd., product name Mowinyl (registered trademark) 727, non-volatile content 50%), 30 parts of ion-exchanged water, 3 parts of film-forming agent (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 2.1 parts of thickener A-1, and 0.5 parts of viscosity adjuster B-1 were added and stirred at 1500 rpm for 5 minutes using a Homo Disper. The resulting water-based coating composition was then transferred to a sealable plastic bottle and stored at room temperature for about a day until the bubbles disappeared, yielding a water-based coating composition.

[0045] (Examples 2 to 5, Comparative Examples 1 to 5 and 8) The viscosity adjuster B-1 was changed to a compound shown in Table 1, and in Example 5 and Comparative Example 8, the resin emulsion was changed to Boncoat (registered trademark) SA-6340 (DIC Corporation, acrylic silicone emulsion, non-volatile content 50%). Except for this, the aqueous coating composition was obtained in the same manner as in Example 1.

[0046] (Comparative Examples 6 and 7) In Comparative Examples 6 and 7, water-based coating compositions were obtained in the same manner as in Example 1, except that the viscosity modifier B-1 was not added and the amount of thickener A-1 was changed.

[0047] [Table 1]

[0048] [Performance evaluation] The water-based coating compositions obtained in the above Examples 1 to 5 and Comparative Examples 1 to 8 were subjected to the following performance evaluation tests (1) and (2). The results are shown in Table 2.

[0049] (1) KU (Krebs) value measurement According to JIS K5600-2-2:1999 General Test Methods for Paints, the KU values ​​of the water-based paint compositions were measured at 10°C, 25°C and 35°C using a Digital Stormer Viscometer KU3 manufactured by Eiko Seiki Co., Ltd., and the KU value ratios were determined at 10°C / 25°C and 10°C / 35°C. The KU value is a value that represents the viscosity based on the relationship between the load and the time required for 100 revolutions when the impeller is rotated under a constant load, and the closer the KU value ratio is to 1, the smaller the temperature dependency. (2) TI (thixotropy index) value measurement Measurements were taken at 25°C, at 6 rpm and 60 rpm using a B-type viscometer manufactured by Toki Sangyo Co., Ltd., and the TI value was calculated by dividing the viscosity measured at 6 rpm by the viscosity measured at 60 rpm. The TI value is the ratio of the viscosity value of the paint at which the viscosity decreases when the viscometer rotation speed is multiplied by 10; the closer the TI value is to 1, the more Newtonian the flow, and the higher the TI value, the more structural viscosity the paint has.

[0050] [Table 2]

[0051] As shown in Table 2, the aqueous coating compositions of Examples 1 to 5 were able to bring the KU value ratio close to 1 without reducing the TI value, and showed little change in KU value between 10°C and 35°C while suppressing sagging, which is necessary for aqueous coating compositions. This shows that aqueous coating compositions with little temperature dependency were obtained while maintaining paint performance.

Claims

1. A viscosity adjuster containing a compound represented by the following general formula (1): [Case 1] (In the formula, R １ is a hydrogen atom, a methyl group, or an ethyl group; R ２ O, R ３ O, R ４ O is an oxyalkylene group having 2 to 4 carbon atoms, a, b, and c are positive numbers satisfying the relationship 15≦a+b+c≦300, and m is 0 or 1.

2. The viscosity modifier according to claim 1, wherein the total proportion of the oxyalkylene groups having 3 carbon atoms and the oxyalkylene groups having 4 carbon atoms is 70 mass% or more, based on the total mass of the oxyalkylene groups in the general formula (1).

3. 3. A water-based coating composition comprising the viscosity modifier and thickener according to claim 1 or 2.

4. 4. The water-based coating composition according to claim 3, wherein the thickener is an associative thickener.

5. 5. The water-based paint composition according to claim 4, wherein the associative thickener is a hydrophobically modified polyether urethane (HEUR).