Water-based base coat composition

Abstract

The present invention provides an aqueous basecoat composition comprising (A) a water-soluble or dispersible film-forming resin selected from polyurethane resins, acrylic resins, and combinations thereof, (B) a curing agent, and (C) an organic solvent containing the following components: (C1) at least one ether having a boiling point of at least 200°C selected from alkyl ethers or aryl ethers of polyols, and (C2) at least one hydrophilic diol having a molecular weight of less than 400 g / mol. The present invention also provides the use of the aqueous basecoat composition in automotive paints.

Description

[Technical Field]

[0001] The present invention relates to an aqueous basecoat composition containing an organic solvent and to the use of the aqueous basecoat composition in automotive paints. [Background technology]

[0002] Water-based automotive coatings have been developed over many years and are becoming increasingly attractive due to growing social awareness of environmental protection and stricter regulations. To obtain a suitable water-based automotive coating, several aspects must be considered, such as coating applicability, and the appearance and performance of the cured film.

[0003] In the current process of automotive OEM (original equipment manufacturer) painting, the appearance of the paint film on the door sill is relatively poorer than that on the body of the car. The reason for this defect is mainly because the process includes a protective step of sealing and baking the underside before painting in the booth, which means the door sill cannot cool as quickly as the body. The higher the temperature of the door sill (30°C to 35°C), the worse the appearance (e.g., gloss) of the film obtained from the same paint. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, it remains desirable to provide a water-based automotive paint that overcomes the above-mentioned problems and at the same time provides a film with good overall appearance on the body as well as the door sill. [Means for solving the problem]

[0005] In one aspect, the present invention provides a composition comprising the following components: (A) a water-soluble or dispersible film-forming resin selected from polyurethane resins, acrylic resins, and combinations thereof; (B) a curing agent, and (C) The following ingredients: (C1) at least one ether having a boiling point of at least 200°C chosen from alkyl or aryl ethers of polyols; (C2) at least one hydrophilic diol having a molecular weight of less than 400 g / mol; an organic solvent containing The present invention provides an aqueous basecoat composition comprising:

[0006] In another aspect, the present invention provides a method of using the waterborne basecoat composition according to the present invention in an automotive paint, preferably an automotive original equipment manufacturer (OEM) paint.

[0007] Surprisingly, it has been found that the use of the aqueous base coat composition according to the present invention significantly improves the appearance (e.g., smoothness and gloss) of the film on the door sill of an automobile. It has also been found that the use of the aqueous base coat composition according to the present invention improves the appearance (e.g., smoothness) of the film on the body of an automobile. DETAILED DESCRIPTION OF THE INVENTION

[0008] It is understood that the present invention can be embodied in various ways and is not limited to the embodiments set forth herein. Unless clearly indicated otherwise, all technical and scientific terms used herein have the common meaning recognized by those skilled in the art. Where in context, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0009] (A) Water-soluble or dispersible film-forming resin Water-soluble or dispersible film-forming resins for use in the aqueous basecoat compositions according to the present invention include any polyurethane resin, acrylic resin, and combinations thereof known in the art to be useful in aqueous coating compositions.

[0010] Suitable polyurethane resins are typically the addition polymerization product of an organic compound having at least two reactive hydrogen functional groups and a polyisocyanate, for example in the form of an aqueous dispersion.

[0011] Organic compounds having at least two reactive hydrogen functional groups are well known in the art, such as polyols. Examples of polyols include, but are not limited to, those described in US Pat. No. 6,384,131 B1, namely:

[0012] - polyols, such as saturated and unsaturated polyhydric alcohols, including ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,4-butenediol, 1,6-hexanediol, furandiethanol, and cyclohexanedimethanol; polyester polyols formed from the reaction of saturated and unsaturated polyhydric alcohols, such as ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1,4-butenediol, 1,6-hexanediol, furandiethanol, and cyclohexanedimethanol, with saturated and unsaturated polycarboxylic acids and their derivatives, such as maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, adipic acid, isophthalic acid, terephthalic acid, phthalic anhydride, dimethyl terephthalate, dimer acid, etc.; polyesters formed by reacting lactones, for example caprolactone, with polyols; polyether polyols, for example products of the polymerization of cyclic oxides, such as ethylene oxide, propylene oxide or tetrahydrofuran; - polyether polyols formed by adding one or more cyclic oxides to water, ethylene glycol, propylene glycol, diethylene glycol, cyclohexanedimethanol, glycerol, or bisphenol A; polycarbonate polyols, such as reaction products of 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol or tetraethylene glycol with diaryl carbonates, such as diphenyl carbonate or phosgene; polyacetal polyols, such as reaction products of glycols, for example diethylene glycol, triethylene glycol or hexanediol, with formaldehyde; polyols, such as dihydroxyalkanoic acids, including dimethylolpropionic acid, and - Any mixture of these.

[0013] Suitable polyisocyanates are also known in the art and include aliphatic, cycloaliphatic, and / or aromatic diisocyanates, and polyisocyanates containing three or more isocyanate groups per molecule. Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, dimethylethylene diisocyanate, methyltrimethylene diisocyanate, and trimethylhexane diisocyanate. Examples of cycloaliphatic diisocyanates include isophorone diisocyanate, cyclopentylene diisocyanate, and hydrogenated products of aromatic diisocyanates, such as cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and dicyclohexylmethane diisocyanate. Examples of aromatic diisocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, naphthylene diisocyanate, and diphenylmethane diisocyanate, or an isomer or isomer mixture thereof.

[0014] Preferably, the polyisocyanate is an aliphatic or cycloaliphatic diisocyanate, with isophorone diisocyanate being particularly preferred.

[0015] Polyurethane resins may be modified for hydrophilic stabilization or to increase dispersibility in aqueous media by introducing cationic or anionic modifying groups, or potentially ionic groups that can be converted to cationic or anionic groups. Such polyurethane resins are often referred to in the art as ionic hydrophilically stabilized polyurethane resins. Alternatively, polyurethane resins may be modified by introducing nonionic hydrophilic modifying groups. Suitable cationic, anionic, and / or nonionic modifications of polyurethane resins are known, for example, from WO 2013 / 128011 A1.

[0016] Polyurethane resins useful in the aqueous basecoat compositions according to the present invention may be prepared by any method known in the art or may be commercially available.

[0017] Examples of commercially available polyurethane resins useful in the waterborne basecoat compositions according to the present invention include DAOTAN® TW1237 / 32WA, available from Allnex Resins Germany GMBH, and Basonol® PU1035W, available from BASF (China) Company Ltd.

[0018] Here, the acrylic resin is not particularly limited, and may be any water-soluble or dispersible poly(meth)acrylate or modified poly(meth)acrylate.Suitable acrylic resins are typically hydroxy-containing acrylic resins.The hydroxy-containing acrylic resins may be copolymers of a hydroxy-containing polymerizable unsaturated monomer and at least one unsaturated monomer copolymerizable with the hydroxy-containing polymerizable unsaturated monomer, and may be in the form of, for example, an aqueous dispersion.

[0019] Hydroxy-containing polymerizable unsaturated monomers are known in the art and include, for example, monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, ε-caprolactone-modified compounds of monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, N-hydroxymethyl (meth)acrylamide, allyl alcohol, and (meth)acrylates with hydroxy-terminated polyoxyethylene chains (described in U.S. Pat. No. 9,701,866 B2).

[0020] The at least one unsaturated monomer copolymerizable with the hydroxy-containing polymerizable unsaturated monomer is not particularly limited and may be appropriately selected depending on the properties required for the hydroxy-containing acrylic resin. Examples of unsaturated monomers copolymerizable with the hydroxy-containing polymerizable unsaturated monomer include, but are not limited to, those described in US9701866B2, such as:

[0021] alkyl or cycloalkyl (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, and tricyclodecanyl (meth)acrylate, isobornyl-containing polymerizable unsaturated monomers, such as isobornyl (meth)acrylate, adamantyl-containing polymerizable unsaturated monomers, such as adamantyl (meth)acrylate, tricyclodecenyl-containing polymerizable unsaturated monomers, such as tricyclodecenyl (meth)acrylate, aromatic ring-containing polymerizable unsaturated monomers, such as benzyl (meth)acrylate, styrene, α-methylstyrene, and vinyltoluene; alkoxysilyl-containing polymerizable unsaturated monomers, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, and γ-(meth)acryloyloxypropyltriethoxysilane; fluorinated alkyl-containing polymerizable unsaturated monomers, such as perfluorobutylethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, and perfluoroalkyl (meth)acrylates, and fluoroolefins, - polymerizable unsaturated monomers having photopolymerizable functional groups, such as maleimides; vinyl compounds, such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, and vinyl acetate; phosphoric acid group-containing polymerizable unsaturated monomers, such as 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, and 2-methacryloyloxypropyl acid phosphate; carboxy-containing polymerizable unsaturated monomers, such as (meth)acrylic acid, maleic acid, crotonic acid, and β-carboxyethyl acrylate; nitrogen-containing polymerizable unsaturated monomers, such as (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, 2-(methacryloyloxy)ethyltrimethylammonium chloride, and addition products of glycidyl (meth)acrylate with amines; polymerizable unsaturated monomers having at least two polymerizable unsaturated groups per molecule, such as allyl(meth)acrylate and 1,6-hexanediol di(meth)acrylate, epoxy-containing polymerizable unsaturated monomers, such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, and allyl glycidyl ether; - (meth)acrylates with alkoxy-terminated polyoxyethylene chains, sulfonic acid group-containing polymerizable unsaturated monomers, such as 2-acrylamido-2-methylpropane-sulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, and 4-styrenesulfonic acid, and the sodium or ammonium salts of these sulfonic acids; - UV-absorbing functional group-containing polymerizable unsaturated monomers, such as 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, and 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole, light-stable polymerizable unsaturated monomers, such as 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, - Carbonyl-containing polymerizable unsaturated monomers, such as acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoacetoxyethyl methacrylate, formyl styrene, and C 4~7 Vinyl alkyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, and vinyl butyl ketone).

[0022] The hydroxy-containing acrylic resin preferably has an acid value of 1 to 200 mgKOH / g, more preferably 2 to 180 mgKOH / g.

[0023] Hydroxy-containing acrylic resins useful in waterborne basecoat compositions according to the present invention may be prepared by any method known in the art or may be commercially available.

[0024] Examples of commercially available hydroxy-containing acrylic resins useful in waterborne basecoat compositions according to the present invention include Setaqua® 6160, Viacryl® VSC6800W / 47WA and Viacryl® VSC6276W / 44WA, available from Allnex Resins Germany GMBH.

[0025] (B) Hardener The curing agent may be any compound capable of reacting with the water-soluble or dispersible film-forming resin (A) and thereby curing the aqueous basecoat composition of the present invention. Examples of the curing agent (B) include amino resins, polyisocyanates, blocked polyisocyanates, epoxy-containing compounds, carboxy-containing compounds, and carbodiimide-containing compounds, which may be used alone or in combination of two or more. Among these, amino resins, polyisocyanate compounds, and blocked polyisocyanate compounds are preferred, and amino resins are particularly preferred.

[0026] Examples of suitable amino resins include partially or fully methylolated amino resins obtained by reacting an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide with an aldehyde component such as formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Methylolated amino resins in which at least a portion of the methylol groups are alkylated with a suitable alcohol, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, and 2-ethylhexanol, may also be useful.

[0027] As an example of an amino resin, melamine resins are particularly useful in the aqueous base coat composition of the present invention. In particular, methylated melamine resins obtained by etherifying at least a portion of the methylol groups of partially or completely methylolated melamine resins with methyl alcohol, butylated melamine resins obtained by etherifying at least a portion of the methylol groups of partially or completely methylolated melamine resins with butyl alcohol, and methylated / butylated melamine resins obtained by etherifying at least a portion of the methylol groups of partially or completely methylolated melamine resins with methyl alcohol and butyl alcohol are preferred. Examples of commercially available amino resins useful in the waterborne basecoat compositions according to the present invention include Cymel® 202, Cymel® 203, Cymel® 211, Cymel® 251, Cymel® 324, Cymel® 325, Cymel® 327, Cymel® 350, Cymel® 385, Cymel® 1130, Cymel® 1156, Cymel® 1116, Cymel® 1158, available from Allnex USA Inc., Cymel® 204, Cymel® 238, Cymel® 303, Cymel® 323, available from Cytec Industries Inc., and U-VAN®. (商標) 120, U-VAN (商標) 20HS, U-VAN (商標) 20SE60, U-VAN (商標) 2021, U-VAN (商標) 2028 and U-VAN (商標) 28-60, manufactured by Mitsui Chemicals, Inc.

[0028] Examples of suitable polyisocyanates include aliphatic polyisocyanates, such as trimethylene diisocyanate, 1,2-propylene diisocyanate, tetramethylene diisocyanate, 2,3-butylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4, ... methylhexamethylene diisocyanate, dodecamethylene diisocyanate, α,α'-dipropyl ether diisocyanate, and transvinylidene diisocyanate, alicyclic polyisocyanates such as 1,3-cyclopentylene diisocyanate, 1,2-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 4-methyl-1,3-cyclohexylene diisocyanate, 4,4'-dicyclohexylene Diisocyanatomethane, 3,3'-dimethyl-4,4'-dicyclohexylene diisocyanatomethane, norbornane diisocyanate, and isophorone diisocyanate, aromatic polyisocyanates such as m- and p-phenylene diisocyanate, 1,3- and 1,4-bis(isocyanatomethyl)benzene, 1,5-dimethyl-2,4-bis(isocyanatomethyl)benzene, 1,3,5-triisocyanatobenzene, Included are 2,4- and 2,6-toluene diisocyanate, 2,4,6-toluene triisocyanate, α,α,α',α'-tetramethyl o-, m-, and p-xylylene diisocyanate, 4,4'-diphenylene diisocyanate methane, 4,4'-diphenylene diisocyanate, 3,3'-dichloro-4,4'-diphenylene diisocyanate, and naphthalene-1,5-diisocyanate, and any combination thereof.

[0029] Adducts of polyisocyanates, such as biurets, isocyanurates, allophonates, uretdiones, and prepolymers of polyisocyanates, are also useful as curing agents. Additionally, (co)polymers of isocyanate-functional monomers, such as α,α'-dimethyl-m-isopropenylbenzyl isocyanate, are also suitable.

[0030] Examples of suitable blocked polyisocyanates include the above-mentioned isocyanates and adducts thereof that have been modified by blocking the isocyanate groups (-NC=O groups) with a blocking agent. Blocking agents include oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monoxime, benzophenone oxime, and cyclohexane oxime; alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol, benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate; phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methylhydroxybenzoate; ethers such as ethylene glycol, monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ...ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; active methylene compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; mercaptans such as butyl mercaptan, tert-butyl mercaptan, hexyl mercaptan, tert-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, and ethylthiophenol; amides such as acetanilide, acetanisidide, acetotolimide, acrylamide, methacrylamide, acetic amide, stearic acid amide, and benzamide; imides such as succinimide, phthalimide, and maleimide; amines such as diphenylamine, phenylnaphthylamine, xylidine;N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylphenylamine, imidazole or imidazole derivatives, ureas such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea, carbamates such as phenyl N-phenylcarbamate, imines such as ethyleneimine and propyleneimine, sulfites such as sodium bisulfite and potassium bisulfite, and azoles such as pyrazole or pyrazole derivatives.

[0031] (C) Organic solvent Surprisingly, it has been found that coatings with better appearance can be provided by using an organic solvent in a water-borne base coat comprising (C1) at least one ether having a boiling point of at least 200°C selected from alkyl or aryl ethers of polyols, and (C2) at least one hydrophilic diol having a molecular weight of less than 400 g / mol.

[0032] As ether (C1), any alkyl or aryl ether of a polyol may be used, having a boiling point of at least 200°C and preferably a molecular weight of less than or equal to 500 g / mol. Alkyl or aryl ethers of polyols having a boiling point of between 200°C and 300°C are more preferred. Here, the boiling point in each case refers to the boiling point under a pressure of 1 atmosphere, unless otherwise specified.

[0033] The alkyl or aryl ether of a polyol may be a mono- or dialkyl ether of a polyol, a mono- or diaryl ether of a polyol, particularly a mono- or dialkyl ether of a diol, a mono- or diaryl ether of a diol. Examples of alkyl or aryl ethers of a polyol include, but are not limited to, alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, alkylene glycol monoaryl ethers, alkylene glycol diaryl ethers, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl ethers, dialkylene glycol monoaryl ethers, dialkylene glycol diaryl ethers, trialkylene glycol monoalkyl ethers, trialkylene glycol dialkyl ethers, trialkylene glycol monoaryl ethers, and trialkylene glycol diaryl ethers.

[0034] Suitable alkylene glycols from which the alkyl or aryl ethers of the polyols are derived are selected, for example, from linear or branched C2-C20-alkylene glycols, preferably linear or branched C2-C10-alkylene glycols, in particular linear or branched C2-C6-alkylene glycols. Examples of alkylene glycols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, and 1,18-octadecanediol.

[0035] Suitable dialkylene glycols from which the alkyl or aryl ethers of the polyols are derived are, for example, di-C2-C10-alkylene glycols, preferably di-C2-C6-alkylene glycols, more preferably di-C2-C4-alkylene glycols.

[0036] Suitable trialkylene glycols from which the alkyl or aryl ethers of the polyols are derived are, for example, tri-C2-C6-alkylene glycols, preferably tri-C2-C4-alkylene glycols.

[0037] The alkyl moiety in the alkyl ether of the polyol is linear or branched alkyl, preferably C1-C20-alkyl, more preferably C3-C10-alkyl, most preferably C4-C8-alkyl.

[0038] The aryl moiety in the alkyl ether of the polyol is, for example, unsubstituted or substituted phenyl, preferably phenyl and C1-C10-alkyl substituted phenyl.

[0039] Preferred examples of alkyl or aryl ethers of polyols include, but are not limited to, diethylene glycol monobutyl ether (BDG), triethylene glycol monobutyl ether (BTG), diethylene glycol monoisobutyl ether (iBDG), diethylene glycol monohexyl ether (HeDG), ethylene glycol mono 2-ethylhexyl ether (EHG), diethylene glycol mono 2-ethylhexyl ether (EHDG), ethylene glycol monophenyl ether (PhG), and diethylene glycol monophenyl ether (PhDG).

[0040] Suitable hydrophilic diols (C2) are diols having an HLB value of at least 9, and in particular alkylene glycols and dialkylene glycols having an HLB value of at least 9 and a molecular weight of less than 400 g / mol, the HLB value in each case referring to the value according to the Griffin method, unless otherwise specified.

[0041] In particular, useful alkylene glycols are selected from linear or branched C2-C20-alkylene glycols, preferably linear or branched C2-C10-alkylene glycols, in particular linear or branched C2-C6-alkylene glycols. Examples of hydrophilic alkylene glycols include, but are not limited to, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, and 3-methyl-1,5-pentanediol.

[0042] Useful dialkylene glycols are selected from di-C2-C10-alkylene glycols, preferably di-C2-C6-alkylene glycols, more preferably di-C2-C4-alkylene glycols. Particularly suitable dialkylene glycols are diethylene glycol, dipropylene glycol or combinations thereof.

[0043] The ether (C1) and the hydrophilic diol (C2) may be used in a mass ratio of 5:2 to 2:5, preferably 2:1 to 1:2, more preferably 3:2 to 2:3.

[0044] The ether (C1) and the hydrophilic diol (C2) may be contained in the aqueous base coat composition according to the present invention in a total amount of 1 to 8% by mass, preferably 2 to 8% by mass, and more preferably 3 to 6% by mass, based on the mass of the aqueous base coat composition.

[0045] It is understood that the ether (C1) and the hydrophilic diol (C2) are used in the presence of additional organic solvents conventionally used in aqueous base coat compositions. In particular, the organic solvent (C) may comprise at least one organic solvent selected from the group consisting of hydrocarbon solvents such as mineral spirits, toluene, xylene, and solvent naphtha, alcoholic solvents other than solvents (C1) and (C2), such as 1-hexanol, 1-octanol, 2-octanol, 2-ethyl-1-hexanol, and 1-decanol, benzyl alcohol, ester solvents such as n-butyl acetate, isobutyl acetate, isoamyl acetate, and methyl amyl acetate, and ketone solvents such as methyl isobutyl ketone, cyclohexanone, ethyl n-amyl ketone, and diisobutyl ketone.

[0046] The organic solvent (C) may be contained in the aqueous base coat composition according to the present invention in a total amount of 1 to 15% by mass, preferably 2 to 12% by mass, and more preferably 3 to 10% by mass, based on the mass of the aqueous base coat composition.

[0047] The aqueous base coat compositions according to the invention further comprise color pigments, such as white and black pigments, effect pigments or combinations thereof. Suitable color and effect pigments are known in the art and are described, for example, in Römpp-Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, pp. 176 and 451.

[0048] The aqueous base coat composition optionally contains at least one additional film-forming resin in addition to the water-soluble or dispersible film-forming resin (A). The at least one additional film-forming resin may be appropriately selected by a person skilled in the art depending on the practical needs of the coating film.

[0049] Examples of the at least one additional film-forming resin include polyester resins, which are esterification or transesterification products of carboxylic acids and / or carboxylic anhydrides with hydroxyl-containing compounds.

[0050] As suitable carboxylic acid, polycarboxylic acid having at least two carboxyl groups per molecule is generally used for preparing polyester resin.Examples of polycarboxylic acid include aliphatic polycarboxylic acid such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, succinic acid, fumaric acid, maleic acid and itaconic acid; aromatic polycarboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid and pyromellitic acid; alicyclic polycarboxylic acid such as tetrahydrophthalic acid, tetrahydroisophthalic acid, tetrahydroterephthalic acid, hexahydrophthalic acid, hexahydroisophthalic acid and hexahydroterephthalic acid, which can be used alone or in combination of two or more.

[0051] Additionally or alternatively, anhydrides of polycarboxylic acids may be used in the esterification or transesterification. Anhydrides of the polycarboxylic acids mentioned above, such as succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, phthalic anhydride, trimellitic anhydride and pyromellitic anhydride may be used.

[0052] Suitable hydroxyl group-containing compound is polyhydric alcohol having two or more hydroxyl groups per molecule, which is generally used for preparing polyester resin.Example of hydroxyl group-containing compound includes alkylene glycol, such as ethylene glycol, propylene glycol, diethylene glycol, 1,3-propanediol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4 -trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol and neopentyl glycol, ester diols such as bis(hydroxyethyl) terephthalate, polyether diols such as polyethylene glycol, polypropylene glycol and polybutylene glycol, trihydric or higher polyhydric alcohols such as glycerol, trimethylolethane, trimethylolpropane, diglycerol, triglycerol, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol and mannitol, which may be used alone or in combination of two or more.

[0053] The hydroxy-containing polyester resin may be modified with, for example, a fatty acid, a monoepoxy compound, a polyisocyanate compound, or the like during or after the preparation of the resin.

[0054] Hydroxy-containing polyester resins useful in the waterborne basecoat compositions according to the present invention may be prepared by any method known in the art or may be commercially available.

[0055] Further examples of the at least one additional film-forming resin include polyurethane resins and acrylic resins. At least one film-forming polyurethane and / or acrylic resin other than the species as the water-soluble or dispersible film-forming resin (A) can be used as the at least one additional film-forming resin.

[0056] The waterborne basecoat compositions according to the present invention may also optionally include one or more of the following additives known to those skilled in the art: solidification / curing catalysts, thickeners, surface modifiers, wetting agents, defoamers, plasticizers, fillers, film-forming aids, ultraviolet absorbers, light stabilizers, antioxidants, etc.

[0057] The formulation of the aqueous base coat composition according to the present invention is not particularly limited and may be in the form of a one-pack or multi-pack type. In particular, the aqueous base coat composition may be formulated in accordance with the formulation of conventional aqueous automotive base coats by using the ether (C1) and the hydrophilic diol (C2).

[0058] It will be appreciated that the aqueous basecoat composition according to the present invention may already contain a total amount of aqueous medium to provide a suitable viscosity for painting purposes. The aqueous basecoat composition according to the present invention may be diluted to a suitable viscosity by adding additional water and / or a small amount of organic solvent before painting.

[0059] There are no particular limitations on the method for preparing the aqueous base coat composition of the present invention, and any method known in the art may be used, such as kneading a mixture of the resin and pigment, and dispersing using a ball mill, sand mill, disperser, or the like.

[0060] The aqueous basecoat composition according to the present invention may be applied by any conventional coating method, such as air spray coating, air atomized electrostatic coating, rotary bell atomized electrostatic coating, etc., preferably following the prior application of a primer layer comprising an electrodeposited coating material and / or a sealing material, for example in an automotive painting process.

[0061] In general, the aqueous base coat composition according to the present invention is applied so as to obtain a coating film having a thickness of 5 to 100 μm, preferably 10 to 60 μm, after curing, and then cured for a suitable time, for example, 10 minutes to 1 hour, at a temperature in the range of, for example, 100 to 200° C., preferably 120 to 180° C., and thus obtained.

[0062] The present invention is further illustrated by examples which are not intended to limit the scope of the invention.

[0063] Embodiment 1. The following ingredients: (A) a water-soluble or dispersible film-forming resin selected from polyurethane resins, acrylic resins, and combinations thereof; (B) a curing agent, and (C) The following ingredients: (C1) at least one ether having a boiling point of at least 200°C chosen from alkyl or aryl ethers of polyols; (C2) at least one hydrophilic diol having a molecular weight of less than 400 g / mol; an organic solvent containing 1. A water-based basecoat composition comprising:

[0064] Embodiment 2. The aqueous basecoat composition of embodiment 1, further comprising a pigment, and preferably a white or black pigment.

[0065] Embodiment 3. The aqueous base coat composition according to any one of embodiments 1 to 2, wherein component (C1) is at least one selected from alkyl ethers or aryl ethers of polyols having a boiling point of 200°C to 300°C.

[0066] Embodiment 4. The aqueous basecoat composition of any one of embodiments 1 to 3, wherein component (C1) is at least one selected from alkyl ethers or aryl ethers of polyols having a molecular weight of 500 g / mole or less.

[0067] Embodiment 5. The aqueous basecoat composition of any one of embodiments 1 to 4, wherein component (C1) is at least one selected from mono- and di-alkyl ethers of polyols, mono- and di-aryl ethers of polyols, and preferably mono- and di-alkyl ethers of diols, and mono- and di-aryl ethers of diols.

[0068] Embodiment 6. The aqueous base coat composition according to any one of embodiments 1 to 5, wherein component (C1) is at least one selected from alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, alkylene glycol monoaryl ethers, alkylene glycol diaryl ethers, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl ethers, dialkylene glycol monoaryl ethers, dialkylene glycol diaryl ethers, trialkylene glycol monoalkyl ethers, trialkylene glycol dialkyl ethers, trialkylene glycol monoaryl ethers, and trialkylene glycol diaryl ethers.

[0069] Embodiment 7. The aqueous basecoat composition of embodiment 6, wherein the alkylene glycol is selected from linear or branched C2-C20 alkylene glycols, and preferably linear or branched C2-C10 alkylene glycols, and more preferably linear or branched C2-C6 alkylene glycols.

[0070] Embodiment 8. The aqueous basecoat composition of embodiment 6, wherein the dialkylene glycol is selected from di-C2-C10-alkylene glycols, preferably di-C2-C6-alkylene glycols, and more preferably di-C2-C4-alkylene glycols.

[0071] Embodiment 9. The aqueous basecoat composition of embodiment 6, wherein the trialkylene glycol is selected from tri-C2-C6-alkylene glycols, and preferably tri-C2-C4-alkylene glycols.

[0072] Embodiment 10. The aqueous base coat composition of any one of embodiments 6 to 9, wherein the alkyl in the alkyl ether of the polyol is selected from linear or branched alkyl, preferably C1-C20-alkyl, more preferably C3-C10-alkyl and even more preferably C4-C8-alkyl.

[0073] Embodiment 11. The aqueous basecoat composition of any one of embodiments 6 to 9, wherein the aryl in the alkyl ether of the polyol is selected from unsubstituted or substituted phenyl, and preferably phenyl and C1-C10-alkyl substituted phenyl.

[0074] Embodiment 12. An aqueous base coat composition according to any one of embodiments 1 to 11, wherein component (C1) is at least one selected from the group consisting of diethylene glycol monobutyl ether (BDG), triethylene glycol monobutyl ether (BTG), diethylene glycol monoisobutyl ether (iBDG), diethylene glycol monohexyl ether (HeDG), ethylene glycol mono 2-ethylhexyl ether (EHG), diethylene glycol mono 2-ethylhexyl ether (EHDG), ethylene glycol monophenyl ether (PhG), and diethylene glycol monophenyl ether (PhDG).

[0075] Embodiment 13. The aqueous basecoat composition of any one of embodiments 1 to 12, wherein the hydrophilic diol has an HLB value of at least 9.

[0076] Embodiment 14. The aqueous base coat composition of any one of embodiments 1 to 13, wherein component (C2) is at least one selected from di-C2-C10-alkylene glycols, preferably di-C2-C6-alkylene glycols, and more preferably di-C2-C4-alkylene glycols.

[0077] Embodiment 15. The aqueous base coat composition of any one of embodiments 1 to 12, wherein component (C2) is at least one selected from diethylene glycol and dipropylene glycol.

[0078] Embodiment 16. The aqueous base coat composition of any one of embodiments 1 to 15, wherein the mass ratio of component (C1) to component (C2) is 5:2 to 2:5, preferably 2:1 to 1:2, and more preferably 3:2 to 2:3.

[0079] Embodiment 17. The aqueous base coat composition of any one of embodiments 1 to 16, wherein the weight percentage of components (C1) and (C2) is 1% to 8% by weight, preferably 2% to 8% by weight, and more preferably 3% to 6% by weight, based on the total weight of the aqueous base coat composition.

[0080] Embodiment 18. The aqueous base coat composition of any one of embodiments 1 to 17, comprising, based on the total weight of the aqueous base coat composition, (A) 10% to 30% by weight, calculated on solids, of a film-forming resin, (B) 3% to 10% by weight, calculated on solids, of a curing agent, (C) 5% to 15% by weight, of an organic solvent, (D) 0 to 5% by weight, calculated on solids, of any film-forming resin other than component (A), (E) 0.5% to 5% by weight, of a black pigment, (F) 0 to 5% by weight, of an additive, and (G) 35% to 75% by weight, of water.

[0081] Embodiment 19. The aqueous base coat composition of any one of embodiments 1 to 17, comprising, based on the total weight of the aqueous base coat composition, (A) 5% to 20% by weight, calculated on solids, of a film-forming resin, (B) 1% to 5% by weight, calculated on solids, of a curing agent, (C) 5% to 15% by weight, of an organic solvent, (D) 0 to 10% by weight, calculated on solids, of any film-forming resin other than component (A), (E) 20% to 35% by weight, of a white pigment, (F) 0 to 5% by weight, of an additive, and (G) 35% to 60% by weight, of water.

[0082] Embodiment 20. Use of the waterborne basecoat composition of any one of embodiments 1 to 19 in automotive paints, and preferably automotive original equipment manufacturer (OEM) paints. [Example]

[0083] I. Preparation Examples Example I.1 Preparation of an Aqueous Basecoat Composition (Polar White) 30 parts of polyurethane resin (DAOTAN® TW1237 / 32WA, manufactured by Allnex, solid content approximately 32% by mass), 50 parts of titanium dioxide (Ti-Pure® R-706, manufactured by DuPont), 5 parts of ethylene glycol monobutyl ether, 0.5 parts of triethanolamine, and 14.5 parts of deionized water were mixed, and then a granular ... 50 The mixture was pulverized to obtain a white pigment dispersion paste.

[0084] 18 parts of polyurethane resin (DAOTAN® TW1237 / 32WA, manufactured by Allnex, solid content approximately 32% by weight), 5 parts of acrylic resin (SETAQUA® 6160, manufactured by Allnex, solid content approximately 45% by weight), 45.5 parts of white pigment dispersion paste, 0.3 parts of antifoaming agent, 0.2 parts of wetting agent, and 27.5 parts of an aqueous medium consisting of 22.5 parts of deionized water, 3 parts of triethylene glycol monobutyl ether (BTG), and 2 parts of ethylene glycol (EG) were introduced into a dispersing vessel, and then a particle diameter D 50 Next, 3 parts of melamine resin (Cymel (registered trademark) 203, manufactured by Allnex, solid content approximately 72% by mass) and 0.5 parts of triethanolamine were added and stirred uniformly to obtain extra white paint PW-1.

[0085] Following the same process, waterborne base coat compositions PW-2 to PW-8 were prepared based on the formulations shown in Table 1.

[0086] [Table 1]

[0087] 1 BDG: Diethylene glycol monobutyl ether 2 BTG: Triethylene glycol monobutyl ether 3 EG: Ethylene glycol 4 PG: Propylene glycol 5 Antifoaming agent: Surfynol® 104E, manufactured by Evonik 6 Wetting agent: BYK® 347, manufactured by BYK

[0088] Example I.2 Preparation of an aqueous basecoat composition (deep black) 65 parts of polyurethane resin (DAOTAN® TW1237 / 32WA, manufactured by Allnex, solid content approximately 32% by mass), 10 parts of carbon black (MONARCH® 1300, manufactured by Cabot), 10 parts of diethylene glycol monobutyl ether, 1 part of triethanolamine, and 14 parts of deionized water were mixed, and then a granular material having a particle diameter D of 8 μm or less was added. 50 to obtain a black pigment dispersion paste.

[0089] 35 parts of polyurethane resin (DAOTAN® TW1237 / 32WA, manufactured by Allnex, solid content approximately 32% by mass), 3 parts of acrylic resin (SETAQUA 6160, manufactured by Allnex, solid content approximately 45% by mass), 7 parts of black pigment dispersion paste, 0.3 parts of antifoaming agent, and 49.2 parts of an aqueous medium consisting of 44.2 parts of deionized water, 2.5 parts of triethylene glycol monobutyl ether (BTG), and 2.5 parts of ethylene glycol (EG) were introduced into a dispersion vessel, and then a particle diameter D 50 Next, 5 parts of melamine resin (Cymel (registered trademark) 203, manufactured by Allnex, solid content approximately 72% by mass) and 0.5 parts of triethanolamine were added and stirred uniformly to obtain deep black paint DB1.

[0090] Following the same process, waterborne base coat compositions DB-2 to DB-7 were prepared based on the formulations shown in Table 2.

[0091] [Table 2]

[0092] 1 BDG: Diethylene glycol monobutyl ether 2 BTG: Triethylene glycol monobutyl ether 3 EG: Ethylene glycol 4 PG: Propylene glycol 5 Antifoaming agent: Surfynol® 104E, manufactured by Evonik

[0093] II. Working Examples A zinc phosphate-treated steel plate was coated by electrodeposition with a cationic electrodeposition paint (CathoGuard® 800, manufactured by BASF Coatings GmbH) to obtain a dry coating film having a thickness of 11 μm, and then baked at 175° C. for 25 minutes. The resulting electrodeposition-coated plate was used as a substrate for painting in the following examples (hereinafter referred to as ED plate).

[0094] Example II.1 Preparation and evaluation of ultra-white coatings The ED plate was painted with the extra-white paint prepared in Example I.1 using a rotary sprayer (EcoBell II, Dürr Systems AG, Germany) (flow rate 380 ml / min, rotation speed: 40,000 rpm, voltage: 60 kV) at a temperature of 23°C and a humidity of 65%, resulting in a dry film thickness of 29 μm. After painting, the plate was left for 3 minutes and then flashed off at 80°C for 10 minutes. After cooling to 23°C, a clear coat paint (ProGloss®, BASF Coatings GmbH) was applied to obtain a dry film thickness of 50 μm. After painting, the plate was left for 10 minutes and then baked horizontally at 140°C for 30 minutes to obtain the final plate with an extra-white paint film.

[0095] Another set of extra white coatings was prepared on ED plates following the same process, except that the plates were baked in a vertical position.

[0096] The smoothness of the produced ultra-white coating film was evaluated by Lw and Sw, and the gloss by DOI using an orange peel meter (BYK4840 Wavescan Dual, manufactured by BYK-Gardner GmbH) in accordance with DIN EN ISO 2813. The measurement results are shown in Table 3.

[0097] [Table 3]

[0098] The results shown in Table 3 show that the coatings (Nos. 1 to 4 and Nos. 9 to 12) produced using the aqueous base coat compositions according to the present invention have better smoothness, as represented by lower Lw values, but exhibit comparable gloss, compared to coatings obtained using aqueous base coat compositions that do not contain either organic solvents (C1) or (C2), or contain only one of them.

[0099] Example II.2 Preparation and evaluation of deep black coatings The ED plate was painted with the dark black paint prepared in Example I.2 using a rotary sprayer (EcoBell II, Dürr Systems AG, Germany) (flow rate 380 ml / min, rotation speed: 40,000 rpm, voltage: 60 kV) at a temperature of 23°C and a humidity of 65%, resulting in a dry film thickness of 15 μm. After painting, the plate was left for 3 minutes and then flashed off at 80°C for 10 minutes. After cooling to 23°C, a clear coat paint (ProGloss®, BASF Coatings GmbH) was applied to obtain a dry film thickness of 50 μm. After painting, the plate was left for 10 minutes and then baked horizontally at 140°C for 30 minutes to obtain the final plate with a dark black paint film.

[0100] The produced deep black coating films were also evaluated for smoothness and gloss using the same methods as described in Example II.1. The measurement results are shown in Table 4.

[0101] [Table 4]

[0102] The results shown in Table 4 show that the coatings (Nos. 17 to 20) produced using the aqueous base coat composition according to the present invention have better smoothness, as represented by lower Lw values, but exhibit comparable gloss, compared to coatings obtained using aqueous base coat compositions that do not contain either organic solvents (C1) or (C2), or contain only one of them.

[0103] Example II.3: Simulation of commercial production of extra-white paint on door sills The ED plate was heated to 55°C, and then, while the plate was at 50°C, it was painted with the extra-white paint prepared in Example I.1 using a rotary sprayer (EcoBell II, Duerr Systems AG, Germany) (flow rate 380 ml / min, rotation speed: 40,000 rpm, voltage: 60 kV) at a temperature of 23°C and humidity of 65%, resulting in a dry film thickness of 15 μm. After painting, the plate was left for 3 minutes and then flashed off at 80°C for 10 minutes. After cooling to 23°C, a clear coat paint (ProGloss®, BASF Coatings GmbH) was applied to obtain a dry film thickness of 37 μm. After painting, the plate was left for 10 minutes and then baked horizontally at 140°C for 30 minutes to obtain a final plate with an extra-white paint film.

[0104] The produced ultra-white coating films were evaluated for smoothness and gloss using the same methods as described in Example II.1. The measurement results are shown in Table 5.

[0105] [Table 5]

[0106] Example II.4: Simulation of commercial production of a deep black paint on a door sill The ED plate was heated to 55°C, and then, while the plate was at 50°C, it was painted with the deep black paint prepared in Example I.2 using a rotary sprayer (EcoBell II, Dürr Systems AG, Germany) (flow rate 380 ml / min, rotation speed: 40,000 rpm, voltage: 60 kV) at a temperature of 23°C and humidity of 65%, resulting in a dry film thickness of 10 μm. After painting, the plate was left for 3 minutes and then flashed off at 80°C for 10 minutes. After cooling to 23°C, a clear coat paint (ProGloss®, BASF Coatings GmbH) was applied to obtain a dry film thickness of 37 μm. After painting, the plate was left for 10 minutes and then baked horizontally at 140°C for 30 minutes to obtain the final plate with a deep black paint film.

[0107] The produced deep black coatings were evaluated for smoothness and gloss using the same methods as described in Example II.1. The measurement results are shown in Table 6.

[0108] [Table 6]

[0109] The results shown in Tables 5 and 6 indicate that the coatings (Extra White Nos. 24-27, Deep Black Nos. 32-35) produced using the aqueous basecoat compositions of the present invention have significantly improved smoothness and exhibit better gloss than the corresponding coatings obtained using aqueous basecoat compositions containing neither organic solvent (C1) nor (C2), or only one of them. The loss of film gloss and smoothness due to the high temperature of the substrate before painting was largely prevented by the aqueous basecoat compositions of the present invention. By using the aqueous basecoat compositions of the present invention for automotive OEM painting, it can be expected that the appearance of the coating on the door sill will be significantly improved.

Claims

1. The following ingredients: (A) a water-soluble or dispersible film-forming resin selected from polyurethane resins, acrylic resins, and combinations thereof; (B) a curing agent, and (C) the following components: (C1) at least one ether having a boiling point of at least 200°C selected from alkyl or aryl ethers of polyols; (C2) at least one hydrophilic diol having a molecular weight of less than 400 g / mol; an organic solvent containing Including, The weight percentage of components (C1) and (C2) is 1% to 8% by weight, based on the total weight of the aqueous base coat composition.

2. The aqueous basecoat composition of claim 1 further comprising a pigment.

3. 3. The aqueous base coat composition according to claim 1, wherein the component (C1) is at least one selected from alkyl ethers or aryl ethers of polyols having a boiling point of 200°C to 300°C.

4. 4. The aqueous base coat composition of claim 1, wherein component (C1) is at least one selected from alkyl or aryl ethers of polyols having a molecular weight of 500 g / mol or less.

5. 5. The aqueous base coat composition according to claim 1, wherein component (C1) is at least one selected from mono- and di-alkyl ethers of polyols, mono- and di-aryl ethers of polyols.

6. 6. The aqueous base coat composition according to claim 1, wherein component (C1) is at least one selected from alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, alkylene glycol monoaryl ethers, alkylene glycol diaryl ethers, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl ethers, dialkylene glycol monoaryl ethers, dialkylene glycol diaryl ethers, trialkylene glycol monoalkyl ethers, trialkylene glycol dialkyl ethers, trialkylene glycol monoaryl ethers, and trialkylene glycol diaryl ethers.

7. The aqueous basecoat composition of claim 6, wherein the alkylene glycol is selected from linear or branched C2 to C20-alkylene glycols.

8. The aqueous basecoat composition of claim 6, wherein the dialkylene glycol is selected from di-C2 to C10-alkylene glycols.

9. The aqueous basecoat composition of claim 6, wherein the trialkylene glycol is selected from tri-C2 to C6-alkylene glycols.

10. 10. The aqueous basecoat composition of any one of claims 6 to 9, wherein the alkyl in the alkyl ether of the polyol is selected from linear or branched alkyl.

11. 10. The aqueous basecoat composition of any one of claims 6 to 9, wherein the aryl in the alkyl ether of the polyol is selected from unsubstituted or substituted phenyl.

12. 12. The aqueous base coat composition according to any one of claims 1 to 11, wherein component (C1) is at least one selected from the group consisting of diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, ethylene glycol mono 2-ethylhexyl ether, diethylene glycol mono 2-ethylhexyl ether, ethylene glycol monophenyl ether, and diethylene glycol monophenyl ether.

13. 13. The aqueous basecoat composition of any one of claims 1 to 12, wherein the hydrophilic diol has an HLB value of at least 9.

14. 14. The aqueous base coat composition according to any one of claims 1 to 13, wherein component (C2) is at least one selected from di-C2 to C10-alkylene glycols.

15. 13. The aqueous base coat composition of claim 1, wherein component (C2) is at least one selected from diethylene glycol and dipropylene glycol.

16. 16. The aqueous base coat composition according to any one of claims 1 to 15, wherein the mass ratio of component (C1) to component (C2) is from 5:2 to 2:

5.

17. 17. The aqueous base coat composition of any one of claims 1 to 16, wherein the weight percentage of components (C1) and (C2) is 3% to 6% by weight, based on the total weight of the aqueous base coat composition.

18. 18. Use of the aqueous basecoat composition of any one of claims 1 to 17 in automotive paints.

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