JP2005179484A - Water-based coating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based coating material which excels in storage stability and appearance of a coated article on which a top coat is further applied after coating and heat-cured. <P>SOLUTION: The water-based coating material is composed of the essential components of an anionic polyurethane resin (A) containing 0.1-6 wt% of a carboxylate group and/or a sulfonate group based on the weight of the polyurethane resin, a nonionic surfactant (B) having a cloud point of 60-100°C, and a water-soluble inorganic salt (C), with a weight ratio (A)/(B)/(C) being 65-99.5/0.3-35/0.2-10. A coated article by heat-sensitive coagulation is provided which is obtained by applying the above water-based coating material on a substrate at room temperature and then subjecting to heat-sensitive coagulation at the cloud point of (B) to 105°C. A multi-layer coated article is also provided which is obtained by further applying the top coat on the surface of the coated article by heat-sensitive coagulation and drying at ordinary temperature to 150°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water-based paint, and more particularly to a polyurethane resin-based water-based paint used for construction and automobiles.

Multi-layer coating of water-based paints on metal plates, for example, multi-layer coatings on automobile bodies, is baked at 120 ° C or higher after the intermediate coating is applied on the electrodeposition coating on which the electrodeposition coating is formed. After that, a base paint is applied, a clear coating is performed thereon, and baking is performed at 120 ° C. or higher, which is performed by a so-called 3-coat 2-bake method.
However, in such a coating method, a total of several tens of minutes are required for baking and curing at 120 ° C. or higher, so that the coating process becomes longer, the energy consumption is large, and the cost is disadvantageous. In order to solve this problem, a 3-coat 1-bake method has recently been proposed. For example, a method of applying a paint containing an elastomer as an intermediate coating (see Patent Document 1), a method of applying a paint having a specific Young's modulus and elongation as an intermediate coating (see Patent Document 2), etc. Has been proposed.
JP 2002-126626 A JP 2003-251276 A

  However, in these methods, since the intermediate coating film is not sufficiently solidified, a mixed layer is formed by the application of the top coating material, resulting in a problem that the finished appearance is inferior compared to the 3-coat 2-bake method. An object of the present invention is to provide an anionic polyurethane resin aqueous paint that is excellent in long-term storage stability and excellent in appearance even when a top coat is applied after coating and heat-cured.

  The inventors of the present invention have reached the present invention as a result of studying to obtain a water-based paint capable of solving the above-mentioned problems. That is, the present invention relates to an anionic polyurethane resin (A) containing 0.1 to 6% by weight of a carboxylate group and / or a sulfonate group based on the weight of the polyurethane resin, and a nonionic interface having a cloud point of 60 to 100 ° C. The activator (B) and the water-soluble inorganic salt (C) are essential components, and the weight ratio (A) / (B) / (C) is 65-99.5 / 0.3-35 / 0.2-10. A water-based coating material obtained by applying the water-based coating material to a base material at room temperature and then thermally coagulating at a cloud point of from (B) to 105 ° C .; and on the surface of the heat-sensitive coagulation coating material. Furthermore, a multi-layer coating product obtained by applying a top coating and drying at room temperature to 150 ° C.

  The water-based paint of the present invention has storage stability of the paint, and even if it is heat-sensitively solidified after coating and the top coat is applied on the top coat, there is little mixed layer with the top coat, so that the top coat is coated after heat curing. The appearance is excellent. Moreover, since heat-sensitive coagulation at 60 to 105 ° C. can be performed, the energy consumption is small, which is advantageous in terms of cost. Moreover, it is a paint which can respond | correspond to the 3 coat 1 bake systems, such as a motor vehicle body.

The water-based paint of the present invention comprises an anionic polyurethane resin (A) containing a specific amount of carboxylate groups (—COO ⁻ ) and / or sulfonate groups (—SO ₃ ⁻ ), a nonionic interface having a specific cloud point. The activator (B) and the water-soluble inorganic salt (C) are contained in a specific weight ratio, have long-term storage stability, and the coating temperature after coating is a cloud point of (B) Since it can be heat-sensitively solidified by heating to any temperature of 105 ° C., even if a top coating is applied thereon, mixing is unlikely to occur, and then the appearance of the coating film obtained by heating and drying is applied. It has the feature of being excellent. In the present invention, heat-sensitive coagulation means that the paint coagulates and loses fluidity even when the water is not completely evaporated by heating.

The lower limit of the content of carboxylate groups and / or sulfonate groups in (A) constituting the water-based paint of the present invention is usually 0.1% by weight based on the weight of (A) (in the following, unless otherwise specified,% is Wt%), preferably 0.3%, more preferably 0.4%, particularly preferably 0.5%, and the upper limit is usually 6%, preferably 5%, more preferably 4%. If it is less than 0.1%, the storage stability of the paint is not sufficient, and if it exceeds 6%, the water resistance of the coating film is not sufficient.
The content of the carboxylate group and the sulfonate group in (A) was determined by dissolving the residue obtained by heating and drying 3 to 10 g of the aqueous dispersion of (A) at 130 ° C. for 45 minutes in dimethylformamide, as described in JIS-K0070. It can be calculated from the acid value measured by this method (potentiometric titration method).

  Examples of the counter ion of the carboxylate group or sulfonate group include ammonium cation, amine cation [primary amine cation having 1 to 12 carbon atoms (primary monoamine cation such as methylamine, ethylamine, propylamine, and octylamine cation), Secondary monoamine cations (dimethylamine, diethylamine and dibutylamine cations), tertiary monoamine cations (aliphatic tertiary monoamine cations such as trimethylamine, triethylamine, triethanolamine, N-methyldiethanolamine and N, N-dimethylethanolamine cations; Heterocyclic tertiary monoamine cations such as N-methylpiperidine and N-methylmorpholine cations; benzyldimethylamine, α-methylbenzyldimethylamine; Preliminary N- dimethylaniline aromatic ring-containing tertiary monoamine cation of the cation and the like), an alkali metal cation (sodium, potassium and lithium cations), and combinations of two or more thereof. Among these, an aliphatic tertiary monoamine cation is preferable, and a triethylamine cation is particularly preferable.

In the present invention, (A) is, for example, an organic diisocyanate (a1), a polymer polyol (a2), a carboxyl group (—COOH) and / or a sulfone group (—SO3H) -containing polyol or a salt thereof (a3), and if necessary. Formed from the chain extender (a4) and / or the terminator (a5), and then neutralized with a neutralizing agent (a6) if necessary after the carboxyl group and / or the sulfone group.
Hereinafter, each component will be described.

  As (a1), those conventionally used for polyurethane production can be used. (A1) has 6 to 20 aromatic diisocyanates, 2 to 18 aliphatic diisocyanates, 4 to 15 alicyclic diisocyanates, and carbon numbers (excluding carbon in the NCO group, the same applies hereinafter) 8-15 araliphatic diisocyanates, modified products of these diisocyanates (carbodiimide-modified products, urethane-modified products, uretdione-modified products, etc.) and mixtures of two or more of these.

  Aromatic diisocyanates include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (hereinafter abbreviated as TDI), 2,4′- and / or 4 , 4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4 Examples include '-diisocyanatodiphenylmethane and 1,5-naphthylene diisocyanate.

  Aliphatic diisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2- Isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, and the like.

  Examples of the alicyclic diisocyanate include isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate and the like.

  Examples of the araliphatic diisocyanate include m- and / or p-xylylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, and the like.

  Of these, preferred are aromatic diisocyanates and alicyclic diisocyanates, and particularly preferred are MDI, TDI, isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate.

Examples of the polymer polyol (a2) include polyether diol (a21), polyester diol (a22), and a mixture of two or more thereof.

  Examples of the polyether diol (a21) include compounds having a structure in which an alkylene oxide (hereinafter abbreviated as AO) is added to an active hydrogen atom-containing bifunctional compound, and mixtures of two or more thereof.

  Examples of the active hydrogen atom-containing bifunctional compound include dihydric alcohols, dihydric phenols, and dicarboxylic acids.

Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, bis (hydroxymethyl) cyclohexane and bis (hydroxyethyl). ) Benzene and the like.
Examples of dihydric phenols include catechol and hydroquinone, as well as bisphenols such as bisphenol A, bisphenol F, and bisphenol S.
Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as succinic acid and adipic acid, and aromatic dicarboxylic acids such as phthalic acid and terephthalic acid.
Two or more of the above-mentioned active hydrogen atom-containing compounds can be used.

Examples of AO added to the active hydrogen atom-containing bifunctional compound include ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), 1,2-, 2,3- or 1,3-butylene oxide. , Tetrahydrofuran (hereinafter abbreviated as THF), styrene oxide, α-olefin oxide, epichlorohydrin, and the like.
AO may be used alone or in combination of two or more. In the latter case, block addition, random addition, or a mixture of both may be used.
Among these AOs, preferred are EO alone, PO alone, THF alone, a combination of PO and EO, and a combination of PO and / or EO and THF.
The addition of AO to the active hydrogen atom-containing bifunctional compound can be carried out by a usual method, and is carried out without a catalyst or in the presence of a catalyst (an alkali catalyst, an amine catalyst or an acidic catalyst).

Specific examples of (a21) include polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and polytetramethylene glycol is preferred.

  The polyester diol (a22) includes a low-molecular diol and / or a condensed polyester diol (a221) obtained by reacting a polyether diol having a molecular weight of 1000 or less and a dicarboxylic acid, a low-molecular diol and a mixture thereof, and a lower alcohol (such as methanol). ) And a polylactone diol (a223) obtained by ring-opening polymerization of a lactone, and the like.

  Examples of the low molecular diol include the aforementioned dihydric alcohols, and examples of the polyether diol having a molecular weight of 1,000 or less include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, and a mixture of two or more thereof. .

  Dicarboxylic acids include aliphatic dicarboxylic acids (such as succinic acid, adipic acid, azelaic acid, and sebacic acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid, and phthalic acid), and ester-forming derivatives of these dicarboxylic acids. [Acid anhydride and lower alkyl (1 to 4 carbon atoms) ester and the like] and a mixture of two or more thereof; lactone includes ε-caprolactone, γ-butyrolactone, γ-valerolactone, and two or more thereof Of the mixture.

  The polyesterification reaction may be performed by a usual method, for example, a method in which a low molecular diol and / or a polyether diol having a molecular weight of 1000 or less is reacted (condensed) with a dicarboxylic acid or an ester-forming derivative thereof, or an initiator (a low molecular diol and a low molecular diol). (Or a polyether diol having a molecular weight of 1,000 or less) and a method of adding a lactone.

Examples of (a22) include (a221) [polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentylene adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate Adipate-based condensed polyester diols such as diols and poly (polytetramethylene ether) adipate diol; Azelate-based condensed polyester diols such as polyethylene azelate diol and polybutylene azelate diol; Sebacates such as polyethylene sebacate diol and polybutylene sebacate diol System condensation polyester diol], (a222) [for example, polytetramethyl Such as alkylene carbonate diol and polyhexamethylene carbonate diol] and (A223) [polycaprolactone diol, etc.] and the like.
Among (a22), (a221) and (a222) are preferable.

  The lower limit of the number average molecular weight (hereinafter abbreviated as Mn) of (a2) is preferably 500, more preferably 1,000, and the upper limit is preferably 20,000, more preferably 10,000, particularly preferably 3. , 000.

  Mn of (a2) is determined from the hydroxyl value, and the hydroxyl value can be measured by the method defined in JIS-K0070-1992 (potentiometric titration method).

  The carboxyl group and / or sulfone group-containing polyol or salt (a3) is a component used for introducing a carboxylate group or a sulfonate group for the purpose of self-emulsifying the polyurethane resin in water.

As (a3), a carboxyl group-containing polyol (a31) [dialkylol alkanoic acid {having 6 to 24 carbon atoms, such as 2,2-dimethylolpropionic acid (hereinafter abbreviated as DMPA), 2,2-dialkyl Methylol butanoic acid, 2,2-dimethylol heptanoic acid, 2,2-dimethylol octanoic acid, etc.]], and sulfone group-containing polyol (a32) [sulfonic acid diol {3- (2,3-dihydroxypropoxy) -1 -Propanesulfonic acid and the like} and sulfamic acid diol {N, N-bis (2-hydroxyalkyl) sulfamic acid and its AO adduct}.
Examples of the salt in (a3) include ammonium salts and amine salts [primary amines having 1 to 12 carbon atoms (primary monoamines such as methylamine, ethylamine, propylamine and octylamine) salts, secondary monoamines (dimethylamine, Diethylamine and dibutylmine) salts, tertiary monoamines (trimethylamine, triethylamine, triethanolamine, aliphatic tertiary monoamines such as N-methyldiethanolamine and N, N-dimethylethanolamine; complex such as N-methylpiperidine and N-methylmorpholine Cyclic tertiary monoamines; benzyldimethylamine, α-methylbenzyldimethylamine; and aromatic ring-containing tertiary monoamines such as N-dimethylaniline) salts], alkali metals (sodium, potassium and lithium cations) And combination of two or more thereof.
Among the salts, preferred are amine salts, more preferred are aliphatic tertiary monoamine salts, and particularly preferred are triethylamine salts.

(A4) includes diamines having 2 to 10 carbon atoms (for example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine and toluenediamine); polyamines (for example, diethylenetriamine, triethylenetetramine, etc.); hydrazine or its derivatives (two Basic acid dihydrazides such as adipic acid dihydrazide); polyhydric alcohols having 2 to 15 carbon atoms [the above-mentioned dihydric alcohols, trihydric alcohols (eg glycerin, trimethylolpropane, etc.), EO of these polyhydric alcohols and / or PO low molar adduct (molecular weight less than 500)] and the like.
Of these, ethylenediamine and isophoronediamine are preferred.

Examples of (a5) include monoalcohols having 1 to 8 carbon atoms (such as methanol, ethanol, isopropanol, butanol, cellosolves, and carbitols), and monoamines having 1 to 10 carbon atoms (monomethylamine, monoethylamine, monobutylamine, dioxygen) Butylamine, monooctylamine, monoethanolamine and diethanolamine).
Of these, monoethylamine, monobutylamine and monoethanolamine are preferred.

When (a3) is not a salt and is a carboxyl group and / or sulfone group-containing polyol, the carboxyl group and / or sulfone group is neutralized using (a6) to form a carboxylate group and / or a sulfonate group. can do.
Examples of (a6) include alkaline compounds that form the above-mentioned cations as counterions, such as ammonia, amines [primary amines having 1 to 12 carbon atoms (primary monoamines such as methylamine, ethylamine, propylamine). And octylamine), secondary monoamines (dimethylamine, diethylamine and dibutylamine), tertiary monoamines (aliphatic tertiary monoamines such as trimethylamine, triethylamine, triethanolamine, N-methyldiethanolamine and N, N-dimethylethanolamine; N -Heterocyclic tertiary monoamines such as methylpiperidine and N-methylmorpholine; benzyldimethylamine, α-methylbenzyldimethylamine; and aromatic ring-containing tertiary monoamines such as N-dimethylaniline)], alkali Genus (sodium, potassium and lithium cations), and alkali metal hydroxides, and combinations of two or more of these.
Of these, preferred are amines, more preferred are aliphatic tertiary monoamines, and particularly preferred is triethylamine.

  The amount of (a6) used in the neutralization is usually 20 to 200 mol%, preferably 30 to 150 mol%, based on the total of carboxyl groups and sulfone groups. When the amount of (a6) used is 30% or more, it is preferable from the viewpoint of storage stability of the aqueous dispersion, and when it is 150% or less, it is preferable from the viewpoint that the aqueous dispersion has a low viscosity.

The method for producing the aqueous dispersion (A) in the present invention may be a normal method, and is not particularly limited, but examples thereof include the following methods.
(1) In the presence or absence of an organic solvent (acetone, methyl ethyl ketone, tetrahydrofuran, N, N-dimethylformamide, etc.) that does not contain an active hydrogen-containing group in the molecule, (a1), (a2) and ( The active hydrogen component consisting of a3) is usually 20 by the one-shot method or the multi-stage method with an (NCO / hydroxyl group) equivalent ratio of usually 1.05 to 2.0, preferably 1.1 to 1.6. C. to 150.degree. C., preferably 60.degree. C. to 110.degree. C., to obtain a terminal NCO group-containing urethane prepolymer, and the prepolymer is neutralized with (a6) or while neutralizing, usually at 10.degree. C. to 60.degree. A method of mixing with water containing (a4) and / or (a5), if necessary, preferably at 20 ° C. to 40 ° C., carrying out an emulsification / chain extension reaction until NCO groups are eliminated, and distilling off the organic solvent if necessary.
(2) An active hydrogen component consisting of (a1) and (a2) and (a3) in the presence or absence of an organic solvent, with an (NCO / hydroxyl) equivalent ratio of 0.5 to 0.99 The urethane polymer containing no terminal NCO group is reacted in the range of 1 to 5 by a one-shot method or a multistage method, and this is neutralized in (a6) or mixed and emulsified with water while neutralizing, and an organic solvent is stored if necessary. How to leave.
(3) A one-shot method in which an active hydrogen component consisting of (a1) and (a2) is added in the presence or absence of an organic solvent and the (NCO / hydroxyl) equivalent ratio is in the range of 2.0 to 1.3. Alternatively, the reaction is carried out by a multi-stage method to obtain a urethane polymer containing a terminal NCO group, which is obtained by neutralizing (a3) with (a6) in the range of (NCO / hydroxyl group) equivalent ratio of 1.5 to 1.0. After mixing, emulsifying with water, and then evaporating the organic solvent if necessary.
Of the above methods, the method (1) is preferred.
In order to adjust the carboxylate group and / or sulfonate group in (A) in the present invention to 0.1 to 6% by weight, the charged weight of (a3) in the above methods (1) to (3) is It is preferable to satisfy the following calculation formula (1).

  In order to promote the reaction in the urethanization reaction, a catalyst used in a normal urethane reaction may be used as necessary. Catalysts include amine catalysts such as triethylamine, N-ethylmorpholine, triethylenediamine and cycloamidines described in US Pat. No. 4,524,104 [1,8-diaza-bicyclo (5,4,0) undecene-7. (San Apro / Production, DBU) and the like]; tin-based catalysts such as dibutyltin dilaurate, dioctyltin dilaurate and tin octylate; titanium-based catalysts such as tetrabutyl titanate.

  In the aqueous dispersion (A), those used as a dispersion medium usually include water and a hydrophilic organic solvent, and the hydrophilic organic solvent has a solubility in water of 30/100 g water, for example, 1 Examples include monohydric alcohols (such as methanol, ethanol, isopropanol), glycols (such as ethylene glycol, propylene glycol, and diethylene glycol), trivalent or higher alcohols (such as glycerin), and cellosolves (such as methyl and ethyl cellosolve). Of the dispersion media, preferred is water. When a hydrophilic organic solvent is used in combination, the hydrophilic organic solvent is usually preferably 10% or less based on the total dispersion medium.

  The apparatus that can be used in the process of mixing and emulsifying the urethane prepolymer and the dispersion medium is not particularly limited, and examples thereof include an emulsifier of the following method: 1) vertical stirring method, 2) rotor-stator method [for example “Ebara Milder” (manufactured by Sakakibara Seisakusho)], 3) Line mill method [eg Line Flow Mixer], 4) Static tube mixing type [eg Static Mixer], 5) Vibration type [eg “VIBRO MIXER” 6) Ultrasonic impact type [for example, ultrasonic homogenizer], 7) High pressure impact type [for example, Gaurin homogenizer (Gaurin)], 8) Membrane emulsification type [for example, membrane emulsification module], and 9) Centrifugal thin film contact Formula [eg fill mix]. Of these, 1), 2) and 9) are preferred.

Mn in (A) can be measured by gel permeation chromatography (hereinafter abbreviated as GPC).
In the case of (A) of non-crosslinked type (thermoplastic), it is usually 2,000 to 2,000,000 or more, preferably 10,000 to 1,500,000, particularly 100,000 to 500,000. . The crosslinking type (A) may have a Mn higher than the above range or a high Mn that cannot be measured by GPC.

  The aqueous dispersion (A) in the present invention is preferably of the self-emulsifying type as described above, but if necessary, an emulsifier (a7) may be added in the emulsification / dispersion step.

  Examples of (a7) include the following nonionic surfactant (a71), anionic surfactant (a72), cationic surfactant (a73) and amphoteric surfactant (a74), and a polymeric emulsifying dispersant (a75). For example, those described in US Pat. No. 3,929,678 and US Pat. No. 4,331,447. Two or more of these can be used in combination.

  As (a71), a polyethylene glycol type nonionic surfactant, for example, an aliphatic alcohol (C8-24; hereinafter, carbon number is abbreviated as C) EO and / or PO adduct (p = 1-100; Degree of polymerization is abbreviated as p), alkyl (C1-22) phenol EO and / or PO adduct (p = 1 to 100), alkyl (C8-24) amine EO and / or PO adduct (p = 1 to 1). 100), fatty acids (C8-24) EO and / or PO adducts (p = 1-100) and polypropylene glycol EO adducts (pluronic type); polyhydric alcohol type nonionic surfactants such as polyvalent (divalent) -10 valence or higher) alcohol fatty acid (C8-24) ester [glycerin monostearate, sorbitan monolaurate, etc.] And fatty acid (C8~24) alkanolamide [1: 1 type coconut fatty acid diethanolamide and 1: 1 type of lauric acid diethanol amide] and the like.

  As (a72), an ether carboxylic acid having a C8-24 hydrocarbon group or a salt thereof [sodium lauryl ether acetate, (poly) oxyethylene (p = 1-100) sodium lauryl ether acetate, etc.]; Sulfate ester or ether sulfate having hydrocarbon group and salts thereof [sodium lauryl sulfate, (poly) oxyethylene (p = 1 to 100) sodium lauryl sulfate, (poly) oxyethylene (p = 1 to 100) lauryl sulfate Triethanolamine, (poly) oxyethylene (p = 1 to 100) coconut oil fatty acid monoethanolamide sodium sulfate and the like]; C8-24 hydrocarbon group having a hydrocarbon group [sodium dodecylbenzensulfonate, etc.]; C8 to Has one or two 24 hydrocarbon groups Sulfosuccinate; phosphate ester or ether phosphate ester having C8-24 hydrocarbon group or salt thereof [sodium lauryl phosphate, (poly) oxyethylene (p = 1 to 100) sodium lauryl ether phosphate Etc.]; fatty acid salt having a C8-24 hydrocarbon group [sodium laurate, triethanolamine laurate, etc.]; and acylated amino acid salt having a C8-24 hydrocarbon group [coconut oil fatty acid methyl taurine sodium, coconut Oil fatty acid sarcosine sodium, coconut oil fatty acid sarcosine triethanolamine, N-coconut oil fatty acid acyl-L-glutamic acid triethanolamine, N-coconut oil fatty acid acyl-L-glutamic acid sodium, lauroylmethyl-β-alanine sodium, etc.] It is done.

  (A73) includes quaternary ammonium salt types [stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, ethyl lanolin sulfate fatty acid aminopropylethyl dimethyl ammonium, etc.]; and amine salt types [stearic acid Diethylaminoethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate, etc.].

  (A74) is a betaine-type amphoteric surfactant [coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, laurylhydroxysulfo Betaine, lauroylamidoethylhydroxyethylcarboxymethylbetaine sodium hydroxypropyl phosphate and the like]; and amino acid type amphoteric surfactants [sodium β-laurylaminopropionate and the like].

  As (a75), polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as carboxymethylcellulose, methylcellulose, and hydroxyethylcellulose, carboxyl group-containing (co) polymers such as polyacrylic acid soda, and Mn = 1,000 to 50,000 And a polymer type dispersant having a urethane bond or an ester bond described in US Pat. No. 5,906,704 [for example, polycaprolactone polyol and polyether diol linked with polyisocyanate].

  Among these emulsifiers, (a71) and (a75), particularly (a71) are preferred. Of the (a71), a nonionic surfactant (B) described later having a cloud point of 60 to 100 ° C. is preferable.

The addition amount of the emulsifier is usually 10% or less, preferably 6% or less, particularly 0%, based on the weight of the urethane prepolymer, and is 10% or less, particularly 0%, based on the weight of (A).
When (B) is used as (a71), the amount of (B) used is such that the sum of (B) is the ratio (A) / (B) / (C) = 65-99.5 / 0 described later. It is limited to the quantity of the range which satisfies 3-35 / 0.2-10.

  The emulsifier may be added to either the prepolymer or the aqueous medium or to both. If the emulsifier is reactive with the prepolymer, it is preferably added to the aqueous medium.

The volume average particle size of the aqueous dispersion (A) is preferably 0.01 μm to 1 μm. More preferably, the average particle diameter of 0.02 μm to 0.5 μm can be measured using an ELS-800 electrophoretic light scattering photometer manufactured by Otsuka Electronics Co., Ltd.

The solid content concentration (percentage of components other than the aqueous dispersion medium) in the aqueous dispersion (A) in the present invention is preferably 25 to 75%, more preferably 30 to 70%.
The concentration of (A) in the aqueous dispersion is preferably 20 to 75%, more preferably 25 to 70%.

In the present invention, the nonionic surfactant (B) that can be blended with (A) is the polyethylene glycol type nonionic surfactant of the above-mentioned (a71), and the cloud point is usually 60 to 100 ° C., preferably Is 65 to 95 ° C, more preferably 70 to 90 ° C.
When the cloud point of (B) is less than 60 ° C., a solidified product tends to be generated at a low temperature (less than 60 ° C.) before applying the water-based paint, and the maintenance stability is poor. On the other hand, if the cloud point exceeds 100 ° C., a lot of energy is required for heating after applying the water-based paint. The cloud point can be measured by raising the temperature of a 1% aqueous solution of a nonionic surfactant with stirring and reading the temperature at which it becomes cloudy.

  Specific examples of (B) include aliphatic alcohol EO and adduct [oleyl alcohol EO11-16 adduct (cloud point 78-93 ° C.), lauryl alcohol EO 8-11 mol adduct (cloud point 70-98 ° C.), etc. Alkyl (C8-22) phenol EO adduct [octylphenol EO 9.5 to 14 mol adduct (cloud point 65 to 94) and nonylphenol EO 10 to 16 mol adduct (cloud point 64 to 99 ° C.) and the like]; alkyl ( C8-22) amine EO adducts; and polypropylene glycol EO adducts [polypropylene glycol (Mn = 700) EO 20-30 mol adducts, etc.], and these EO adducts contain small amounts (30 mol% or less) of PO. Or a random or block adduct.

The lower limit of HLB in (B) is preferably 10, more preferably 11, particularly preferably 12, and the upper limit is preferably 18, more preferably 17, particularly preferably 16.
When the HLB of (B) is 10 or more, even when the water-based paint is stored for a long time, a solidified product is not generated and a problem in storage stability hardly occurs. On the other hand, if the HLB is 18 or less, it is preferable because the water-based paint is easily solidified when heated to a cloud point or higher.
HLB in the present invention is a value calculated by the following Griffin method described in Takehiko Fujimoto, “Introduction to New Surfactant”, published by Sanyo Chemical Industries, Ltd. (1992), P128.
HLB = (weight% of hydrophilic group) × (1/5)

The following aliphatic alcohol EO adduct is mentioned as a commercial item of (B).
“Emalmin 110”; cloud point = 77 ° C., HLB = 13.2: “Emalmine 140” manufactured by Sanyo Chemical Industries, Ltd .; cloud point = 91 ° C., HLB = 14.7: “Narrow manufactured by Sanyo Chemical Industries, Ltd.” Acty N100 ”; cloud point = 63 ° C., HLB = 13.3: manufactured by Sanyo Chemical Industries, Ltd.

Examples of the water-soluble inorganic salt (C) that can be blended with (A) in the present invention include the following inorganic salts having a solubility in water of 25 ° C. of 1 or more, preferably 10 or more.
(C) has an action of solidifying the water-based paint, and examples thereof include the following.
Alkali metal salt (C1); alkali metal hydroxide [sodium hydroxide, potassium hydroxide and lithium hydroxide], alkali metal carbonate [sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and lithium carbonate], alkali Metal sulfates [sodium sulfate and potassium sulfate], alkali metal nitrates [sodium nitrate and potassium nitrate], alkali metal phosphates [sodium phosphate, sodium hydrogen phosphate and potassium phosphate], alkali metal sulfites [sodium sulfite, sulfurous acid Sodium hydrogen and potassium sulfite] and alkali metal halides (chlorine, bromine, iodine or fluorine) [sodium chloride, potassium chloride, sodium bromide, potassium iodide and potassium fluoride], etc.
Alkaline earth metal salts (C2); Alkaline earth metals (such as calcium, magnesium, barium and strontium) hydroxides [calcium hydroxide, magnesium hydroxide and strontium hydroxide], alkaline earth metal carbonates [calcium carbonate and Magnesium carbonate], alkaline earth metal sulfate [calcium sulfate and magnesium sulfate], alkaline earth metal nitrate [calcium nitrate and magnesium nitrate], alkaline earth metal phosphate [calcium hydrogen phosphate and magnesium hydrogen phosphate], Alkaline earth metal sulfites [calcium sulfite and magnesium sulfite] and alkaline earth metal halides (chlorine, bromine, iodine or fluorine) [calcium chloride, magnesium chloride, calcium bromide, calcium iodide and fluoride] Magnesium], etc.,
And ammonium salts (C3); halides (such as ammonium chloride and ammonium bromide).
Among these, (C1) is preferable from the viewpoint that the water-based paint can easily obtain a relatively long-term storage stability.

The content of (A) in the aqueous paint of the present invention is preferably 2 to 40%, more preferably 3 to 30%, and the content of (B) is preferably 0.05 to 10%, more preferably 0.1. The content of ˜2% and (C) is preferably 0.01 to 2%, more preferably 0.02 to 0.4%.
The weight ratio of (A), (B) and (C) in the water-based paint is usually 65 to 99.5 / 0.3 to 35 / 0.2 to 10, from the viewpoint of the storage stability of the water-based paint. Preferably it is 70-99.5 / 0.3-30 / 0.2-8, More preferably, it is 75-99.5 / 0.3-25 / 0.2-5.
Furthermore, the weight ratio of (B) / (C) in the water-based paint is preferably 2 to 20/1, more preferably 3 to 15/1. If the ratio of (B) is 3 or more, it is preferable from the viewpoint of the storage stability of the paint, and if it is 20 or less, it is preferable from the viewpoint that temperature-sensitive coagulation is easy.

  In addition to (A), (B) and (C), the water-based paint of the present invention includes pigments, pigment dispersants, other binder resins (such as acrylic resins and polyester resins), viscosity modifiers, antifoaming agents, One or more selected from the group consisting of leveling agents, preservatives, deterioration inhibitors, stabilizers, antifreeze agents, and curing agents can be contained.

Examples of the pigment include inorganic pigments having a solubility in water of 1 or less, such as white pigments (titanium white, zinc white, lithopone, lead white, etc.), black pigments (carbon black, animal black, lead red, etc.), gray pigments (Zinc powder, slate powder, etc.), red pigment (Bengara, red lead, etc.), brown pigment (Amber, iron oxide powder, Bandai tea, etc.), yellow pigment (yellow lead, zinc chromate, yellow iron oxide, etc.), green pigment (Chromium green, chromium oxide, viridian, etc.), blue pigments (ultraviolet, bitumen, etc.), purple pigments (mals purple, pale-mouthed cobalt purple, etc.) and metallic pigments (aluminum flakes, copper bronze flakes, mica-like iron oxide, mica flakes, etc.) ); And organic pigments such as natural organic pigments (such as cochineal lakes, mudder lakes), and synthetic organic pigments such as nitroso pigments (naphthol) Grin Y, Naphthol / Grin B, etc.), Nitro Pigments (Naphthol Yellow S, Pigment Chlorine, Ritor Fast Fast Yellow GG, etc.), Pigment Dye Type Azo Pigments (Toluidine Red, Hansa Yellow, Naphthol AS-G, etc.) ), Azo lakes made from water-soluble dyes (Persian Orange, Ponso 2R, Build-B, etc.), Azo lakes made from poorly soluble dyes (Risor Red, Bone Maroon, Red Lake, etc.), Lakes made from basic dyes (Fanal)・ Color etc.), rakes made from acid dyes (acid green rake, peacock blue rake, etc.), xanthan rakes (eosin etc.), anthraquinone lakes (alizarin rake, pull pudding rake etc.), vat dyes Pigment (In Gore, such as argon-yellow), includes a phthalocyanine pigment (phthalocyanine blue, phthalocyanine green, etc.).
The pigment content is usually 50% or less, preferably 30% or less, based on the weight of the water-based paint.

  Examples of the pigment dispersant include various surfactants [anionic, cationic, nonionic, amphoteric] and polymer type emulsifying dispersant (Mn = 1,000 to 20,000) mentioned as the above-mentioned emulsifier. A polymer type emulsifying dispersant is preferred.

 The content of the pigment dispersant is usually 20% or less, preferably 15% or less, based on the weight of the pigment. In addition, when (B) is used as a pigment dispersant, the total amount of (B) is the above-mentioned ratio (A) / (B) / (C) = 65-99.5 / 0. It is limited to the quantity of the range which satisfies 3-35 / 0.2-10.

  Examples of other binder resins include acrylic resins and melamine resins described in JP-A No. 2003-251276, polyester resins described in JP-A No. 2002-126626, and the like. The content of the other binder resin is usually 40% or less, preferably 30% or less, based on the weight of the aqueous paint. Examples of other commercially available binder resins include acrylic resin emulsion “Polytron Z330” (solid content concentration 51%: manufactured by Asahi Kasei Corporation).

Viscosity modifiers include thickeners such as inorganic viscosity modifiers (such as bentonite), cellulose-based viscosity modifiers (such as methylcellulose, carboxymethylcellulose, and hydroxymethylcellulose), and the weight average molecular weight (hereinafter abbreviated as Mw) is usually 20, 000 or more), protein (casein, casein soda, casein ammonium, etc.), acrylic (sodium polyacrylate, ammonium polyacrylate, etc., Mw is usually 20,000 or more), and vinyl (polyvinyl alcohol, etc., Mw is Usually, 20,000 or more) are mentioned, and acrylic and vinyl are preferable.
The content of the viscosity modifier is usually 5% or less, preferably 3% or less, based on the weight of the aqueous paint.

Examples of the curing agent (h) include the following (h1) to (h4).
(H1) Water-soluble or water-dispersible amino resins such as melamine resins and urea resins containing (alkoxy) methylol groups and / or imino groups [preferably melamine resins containing methylol groups and / or imino groups];
(H2) Water-soluble or water-dispersible polyepoxides such as bisphenol A glycidyl ether, hydrogenated bisphenol A glycidyl ether, polyols (ethylene glycol, glycerin, trimethylolpropane, sorbitol, etc.), and their AO (C2-3) ) Glycidyl ethers of adducts (eg PEG)] and polyepoxides added with an emulsifier (such as the aforementioned surfactants) to give water dispersibility [preferably glycidyl ethers of polyhydric alcohols, especially sorbitol poly (di- -~ Hexa-) glycidyl ether and glycerin poly (di- and tri-) glycidyl ether];
(H3) Water-soluble or water-dispersible polyisocyanate compounds, for example, polyisocyanates having a hydrophilic group (polyoxyethylene chain or the like) in the molecule ["Coronate 3062" and "Coronate 3725" (manufactured by Nippon Polyurethane Industry Co., Ltd.)] And a blocked polyisocyanate [said (a1) (such as isocyanurate-modified IPDI) as a blocking agent (phenols, active methylene compounds, lactams, oximes, bisulfites, tertiary alcohols described in US Pat. No. 4,524,104, Aromatic secondary amines, imides and mercaptans: such as phenol, MEK, ε-caprolactone, etc.)]
(H4) In addition, polyethylene urea (such as diphenylmethane-bis-4,4′-N, N′-ethyleneurea).
Of these, (h1) is preferred.
The content of the curing agent is usually 20% or less, preferably 15% or less, based on the weight of the aqueous paint.

  Anti-foaming agents include long-chain alcohols (such as octyl alcohol), sorbitan derivatives (such as sorbitan monooleate), silicone oils (such as polymethylsiloxane, polyether-modified silicone, and fluorine-modified silicones); Sulfur compounds, organic sulfur halogen compounds, preservatives, etc .; deterioration inhibitors and stabilizers (UV absorbers, antioxidants, etc.) include hindered phenols, hindered amines, hydrazines, phosphoruss, benzophenones, Benzotriazole-based and the like; Antifreeze agents include ethylene glycol and propylene glycol. The content of the antifoaming agent, antiseptic, deterioration preventing agent, stabilizing agent and antifreezing agent is usually 5% or less, preferably 3% or less, based on the weight of the aqueous paint.

In the method for producing a water-based paint of the present invention, all the agents may be mixed simultaneously or each component may be added stepwise. The order in which the components are added is not particularly limited, but when a pigment is blended, it is preferable to add the other components after dispersing the pigment in the aqueous dispersion. In addition, in the addition of (C), it is preferable to add (C) as an aqueous solution (preferably in a concentration of 1 to 30%) in advance in order to prevent local gelation.
Moreover, it may be diluted with water or an aqueous medium containing the above-mentioned hydrophilic organic solvent, if necessary, in addition to the above components.

  The solid content concentration (percentage of components other than the aqueous medium) of the aqueous paint of the present invention is preferably 20 to 70%, more preferably 40 to 60%.

The water-based paint of the present invention has a heat-sensitive coagulation temperature (T) [° C.] of 60 to 100 ° C.
By having T, the coating film is heated to a temperature equal to or higher than T, preferably 60 to 105 ° C., more preferably 5 ° C. higher than T (65 to 105 ° C.) to solidify after coating. Even if a top coat is applied to the film, a mixed layer is unlikely to occur. T can be measured as follows.

10 g of water-based paint diluted to a solid content concentration of 20% is weighed in a test tube (inner diameter: 18 mm) and heated at a rate of 10 ° C./min with no stirring. Let T be the temperature of the water-based paint when the gel is lost.
T is preferably 60 ° C. or more from the viewpoint of storage stability, and preferably 100 ° C. or less from the viewpoint of energy loss during heating. More preferably, it is 60-90 degreeC.
In the present invention, the solid content concentration can be measured by taking 1 to 1.5 g of water-based paint and calculating the percentage of non-volatile components when heated and evaporated at 130 ° C. for 90 minutes.
The aqueous paint of the present invention has a storage stability of at least 30 days at room temperature and at least 10 days at 40 ° C.

  The water-based paint of the present invention can be applied directly to a substrate or via a primer, and can be applied in a single layer or multiple layers (2 to 8 layers). Moreover, although it can be used for any of the undercoat, the intermediate coat, and the top coat, the undercoat and the intermediate coat are preferable in order to exhibit the feature that the mixed layer can be prevented.

  The aqueous paint of the present invention is particularly useful for an intermediate paint such as an automobile. It can also be used as an architectural or industrial paint.

The heat-sensitive coagulation object of the present invention can be obtained, for example, as follows.
Base materials to be painted include metals (aluminum, iron, copper, various alloys, etc.), plastics (vinyl chloride resin, acrylic resin, styrene resin, etc.), inorganic materials (concrete, slate, calcium silicate plate, etc.) Is included. The form of the substrate includes a plate, a rod, a pipe, a block shape, various molded bodies, a structure, and the like.

Application of the water-based paint of the present invention to the substrate can be performed by ordinary coating means (spray coating, brush coating, roll coating, etc.). The viscosity of the paint is appropriately selected according to the coating method. For example, in the case of spray coating, the viscosity at a shear rate of 1000 s-1 is preferably 20 to 50 mPa · s, and the viscosity at a shear rate of 10 s-1 is 180 to 280 mPa · s. If the viscosity at a shear rate of 1000 s-1 is 50 mPa · s or less, it is easy to be sprayed from the spray, and if the viscosity at a shear rate of 10 s-1 is 180 mPa · s or more, sagging is unlikely to occur. These viscosities are measured with a high shear viscometer (“HSV-2” manufactured by Nippon Seiki Co., Ltd.).
The coating amount of the aqueous coating composition of the present invention varies depending on the application and purpose, as an aqueous coating composition itself (wet form), usually 0.5~1,000g / m ^2, preferably from 1 to 300 g / m ^2.
Painting is usually done at room temperature.
The heat-sensitive coagulation is a coating film whose coating film is at least one of 105 ° C. from the cloud point of (B), preferably 5 ° C. or more, more preferably 5 to 10 ° C. higher than the T of the water-based paint. It is preferable to be heated to a temperature. The heating time varies depending on the difference between the heating temperature and T, but is preferably 1 to 10 minutes.
A heating system is not specifically limited, For example, a hot air, infrared rays, an electric heater, and / or sunlight are used, and the temperature of a heating atmosphere is a cloud point -180 degreeC, Preferably it is 65-150 degreeC.

The multi-layer coating product of the present invention is obtained by further applying a top coating material on the surface of the above-mentioned heat-sensitive coagulation object and drying at a temperature of the heating atmosphere from room temperature to 180 ° C. for 30 seconds to several days. Examples of the top coating include solvent-based clear coatings, water-based clear coatings, solvent-based base coatings and water-based base coatings, and water-based coatings are preferred.
The coating amount of the top coat may vary depending on the application and purpose, as a paint itself (wet form), usually 0.5~1,000g / m ^2, preferably from 1 to 300 g / m ^2.

<Example>
EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this. In addition, below, a part shows a mass part.

Production Example 1
Titanium oxide [“CR-93”: manufactured by Ishihara Sangyo Co., Ltd.] 37 parts, carbon black [“FW200P”: manufactured by Degussa Co., Ltd.] 0.5 part, pigment dispersant [“Caron”: Daiichi Kogyo Seiyaku Co., Ltd. Product] 5 parts, 40 parts of ion-exchanged water, and glass beads were added and mixed and dispersed for 30 minutes with a paint conditioner to obtain a pigment paste.

Production Example 2
A closed reaction vessel equipped with a thermometer and a stirrer was charged with 235 parts of polytetramethylene glycol (Mn = 2000), 14.4 parts of DMPA, 70 parts of isophorone diisocyanate and 219 parts of acetone, and the reaction system was replaced with nitrogen gas. The mixture was reacted at 80 ° C. for 6 hours with stirring to obtain an NCO-terminated urethane prepolymer. The obtained product was cooled to 40 ° C. and neutralized by adding 9.8 parts of triethylamine. The neutralized product was emulsified in water, an aqueous solution in which 1.0 part of ethylenediamine was dissolved in 30 parts of water was added, and the mixture was stirred at 40 ° C. for 4 hours to cause a chain elongation reaction. Thereafter, acetone was distilled off under reduced pressure and the concentration was adjusted with water to obtain an aqueous dispersion (U1) of a polyurethane resin having a solid content concentration of 35%. The carboxylate group content was 1.5% based on the polyurethane resin, and the volume average particle size was 0.08 μm.

Production Example 3
A closed reaction vessel equipped with a thermometer and a stirrer was charged with 330 parts of polyhexamethylene carbonate diol (Mn = 2000), 10.5 parts of DMPA, 80 parts of 4,4′-dicyclohexylmethane diisocyanate and 450 parts of acetone, and the reaction system was After substituting with nitrogen gas, the mixture was reacted at 80 ° C. for 6 hours with stirring to obtain an NCO-terminated urethane prepolymer. The product was cooled to 40 ° C. and neutralized by adding 7.99 parts of triethylamine. The neutralized product was emulsified in water, an aqueous solution in which 1.0 part of ethylenediamine was dissolved in 30 parts of water was added, and the mixture was stirred at 40 ° C. for 4 hours to cause a chain elongation reaction. Thereafter, acetone was distilled off under reduced pressure, and the concentration was adjusted with water to obtain an aqueous dispersion (U2) of a polyurethane resin having a solid content concentration of 40%. The carboxylate group content was 0.8% based on the polyurethane resin. The volume average particle diameter was 0.15 μm.

<Manufacture of water-based paint>
Example 1
(1) 100 parts of (U1), 21 parts of a 10% aqueous solution of “Emalmin 110” and 35 parts of a 1% aqueous solution of calcium chloride are mixed in this order, and further prepared with water so that the solid content concentration becomes 23%. Thus, an aqueous dispersion (D1) was obtained.

  (2) 250 parts of the above pigment paste, (D1) 243 parts, "Polytron Z330" 206 parts, and "Cymel 327" 76 parts are mixed with stirring using a propeller blade, and the solid content concentration is increased by adding water to 48 parts. % To obtain a water-based paint (P1).

Example 2
A water-based paint (P2) was obtained in the same manner as in Example 1 except that 88 parts of (U2) was used instead of (U1).

Example 3
A water-based paint (P3) was obtained in the same manner as in Example 1 except that “Emalmin 140” was used instead of “Emalmine 110” as the aliphatic alcohol EO adduct.

Example 4
A water-based paint (P4) was obtained in the same manner as in Example 1 except that “Narrow Acty N100” was used in place of “Emalmine 110” as the aliphatic alcohol EO adduct.

Comparative Example 1
250 parts of the above pigment paste, 160 parts of (U1), 206 parts of “Polytron Z330” and 76 parts of “Cymel 327” were mixed with stirring using a propeller blade, and the solid content concentration was adjusted to 48% by adding water. Water-based paint (X1) was obtained.

Comparative Example 2
An aqueous paint (X2) was obtained in the same manner as in Comparative Example 1 except that 35 parts of a 1% aqueous solution of calcium chloride was further added. However, (X2) was immediately aggregated and coagulated.

Comparative Example 3
A water-based paint (X3) was obtained in the same manner as in Comparative Example 1 except that 21 parts of a 10% aqueous solution of “Emalmine 110” was further added.
Comparative Example 4
As in Example 1, except that “Nonipol Soft FD-80” (cloud point = 34 ° C .: manufactured by Sanyo Chemical Industries, Ltd.) was used as the aliphatic alcohol EO adduct instead of “Emalmine 110”. An aqueous paint (X4) was obtained.

<Storage stability test of water-based paint>
80 ml of the water-based paints (P1) to (P4), (X1), (X3) or (X4) was taken in a glass sedimentation tube having an inner diameter of 2.5 cm and a volume of 100 ml, and stored at 40 ° C.
The appearance was checked once a day and evaluated by the number of days until gelation. The results are shown in Table 1.

<Manufacture of heat-sensitive coagulation substrate>
Examples 5-8 and Comparative Examples 5-7
Water-based paints (P1) to (P4), (X1), (X3) and (X4) were applied to an aluminum plate (7 cm × 15 cm, thickness 0.8 mm) so that the dry film thickness was 30 μm, And heated for 2 minutes at a temperature 5 ° C. higher than the cloud point of (B) used (82 ° C. in Comparative Example 5) to obtain a heat-sensitive coagulation coating.

<Water resistance test of heat-sensitive coagulation substrate>
The water resistance of the heat-sensitive coagulation object was evaluated as a measure of the likelihood of occurrence of a mixed layer after applying the water-based top coating.
Measure the weight (w0) of the above-mentioned aluminum plate and the weight (w1) of the heat-sensitive coagulation object, stainless steel 23cm x 30cm x 4cm with 100 times the weight of [(w1)-(w0)]. The heat-sensitive coagulation coating was immersed in a vat for 1 hour at 25 ° C., and then the heat-sensitive coagulation coating was pulled up. Thereafter, the water in the vat was evaporated to dryness with a vacuum evaporator (90 ° C. × 10 mmHg), and further dried with a forward air dryer at 105 ° C. × 90 minutes, and the weight (w2) of the residue was measured.
The solid content in dissolved and dispersed water was calculated as the dissolution rate by the following formula.
Dissolution rate (%) = (w2) × 100 / [(w1) − (w0)]
The results are shown in Table 2.

<Manufacture of top coat>
Examples 9-12, Comparative Examples 8-10
Spray coating of a commercially available water-based paint [Super Lacquer Spray: manufactured by Asahi Pen Co., Ltd.] on each heat-sensitive coagulation substrate to a dry film thickness of 30 μm, followed by heat curing (140 ° C. × 30 minutes) As a result, a multilayered article having two layers was obtained. The finished appearance of the coating film was visually observed and judged according to the following evaluation criteria.
The results are shown in Table 3.
○: Good (uniform color and no surface irregularities)
Δ: Slightly inferior (there is a slightly non-uniform color, and a slight surface irregularity)
X: Inferior (there are many parts where the color is uneven, and there are many surface irregularities)

  As can be seen from the above test results, the water-based paint of the present invention is excellent in both the storage stability of the paint and the appearance of the top coat.

The water-based paint of the present invention is useful for various coating applications, for example, for automobiles, buildings (wall materials, etc.) and industrial (electric appliances, furniture, etc.). In particular, it is a paint that can be used as an intermediate coating for automobile bodies and the like and can be applied to the 3-coat 1-bake system.

Claims (9)

Anionic polyurethane resin (A) containing 0.1 to 6% by weight of carboxylate group and / or sulfonate group based on the weight of polyurethane resin, nonionic surfactant (B) having a cloud point of 60 to 100 ° C. And a water-based paint having a water-soluble inorganic salt (C) as an essential component and a weight ratio (A) / (B) / (C) of 65 to 99.5 / 0.3 to 35 / 0.2 to 10. The water-based paint according to claim 1, wherein the water-based paint is heat-coagulated by being heated to a cloud point of -105 ° C of the nonionic surfactant (B). The water-based paint according to claim 1 or 2, wherein the nonionic surfactant (B) is a polyethylene glycol type nonionic surfactant having an HLB of 10 to 18. The water-based paint according to any one of claims 1 to 3, wherein the water-soluble inorganic salt (C) is an alkali metal and / or alkaline earth metal salt. The water-based paint according to any one of claims 1 to 4, wherein the solubility of the water-soluble inorganic salt (C) in water is 10 or more. Furthermore, the water-based coating material in any one of Claims 1-5 containing 1 or more types chosen from the group which consists of a pigment, a pigment dispersant, an acrylic resin, a polyester resin, a viscosity modifier, and a hardening | curing agent. The water-based paint according to any one of claims 1 to 6, which is a paint for construction, automobile or industry. A heat-sensitive coagulation object obtained by applying the water-based paint according to any one of claims 1 to 7 to a base material at room temperature and then heat-coagulating the nonionic surfactant (B) at a temperature of cloud point to 105 ° C. A multi-layer coating obtained by further applying a top coating to the surface of the heat-sensitive coagulation coating according to claim 8 and drying at room temperature to 150 ° C.