JPH07252449A - Aqueous coating compound composition and method for forming coating film - Google Patents

Abstract

PURPOSE:To obtain a polyester-based thermosetting aqueous coating compound composition, especially a middle coating compound composition useful for a coating method in which a middle coating layer is applied to an electro-deposition coating layer, baked and cured and a top coating layer is applied. CONSTITUTION:This aqueous coating compound composition is obtained by dissolving or dispersing (a) a polyester resin which comprises 1-30wt.% based on the total of the whole reactive components of a hydroxyl group end polyalkadienediol having 5-50 average polymerization degree, a hydrogenated polyalkadienediol alone or its mixture and has 5-150 acid value and 30-250 hydroxyl number and (b) a crosslinking agent into a base-containing aqueous medium. The aqueous coating compound composition may contain fine powder of a carboxyl group-containing resin.

Description

Detailed Description of the Invention

The present invention relates to a thermosetting polyester resin aqueous coating composition. In particular, the present invention relates to a water-based coating composition suitable for use as an intermediate coating layer applied on an electrodeposition coating film, for example, in the coating of automobile bodies.

[0002] In recent years environmental protection, have gathered interest from the point of view of saving resources and energy saving in the use of water-based paints. For example, in the coating of automobile bodies, it is usual to apply an intermediate coating layer such as a chipping sealer layer and a primer layer on the electrodeposition coating film, and further apply a solid or metallic color coating thereon. In this case, not only the use of organic solvent can be avoided by using water-based paint for the intermediate coating layer, but also the intermediate coating material can be applied wet-on-wet on the electrodeposition coating layer. When cured, shortening of the painting process can also be achieved.

A water-soluble or water-dispersible polyester resin (including an alkyd resin) is used as a vehicle resin for such an aqueous intermediate coating composition. However, since the viscosity of the solution increases as the degree of neutralization of the acid groups of the polyester resin by the base increases, the coating solid content decreases when the coating viscosity is adjusted to an appropriate level, and the coating workability such as sagging and armpitting properties decreases. There was a problem. Therefore, if it is attempted to obtain satisfactory coating workability by lowering the degree of neutralization, lowering the viscosity of the solution, and increasing the solid content of the coating, the water dispersion stability of the water-soluble varnish will decrease, which is not practical. The viscosity is the molecular weight,
In particular, since it increases in proportion to the weight average molecular weight, when a resin having a relatively low molecular weight is used, the solution viscosity can be lowered even at the neutralization degree satisfying the water dispersion stability, and thus the coating solid content can be increased. However, in this case, workability and dispersion stability are satisfied, but sufficient coating performance cannot be obtained.

Therefore, what is required of the water-based paint used as such an intermediate coating layer is workability that does not cause pinholes, dents, sagging, etc. even when applied to a satisfactory film thickness, and sufficient coating film performance. Can be compatible. The coating compositions of the present invention are superior to conventional polyester midcoats in their performance when compared at the same coating viscosity.

DISCLOSURE OF THE INVENTION In the present invention , (a) a hydroxyl group-terminated polyalkadiene diol alone having an average degree of polymerization of 5 to 50, a hydrogenated polyalkadiene diol alone, based on the total amount of all reaction components,
Or containing 1 to 30% by weight of a mixture thereof and having an acid value of 5 to 15
Provided is a thermosetting aqueous coating composition obtained by dissolving or dispersing a polyester resin having a hydroxyl value of 30 to 250 and a crosslinking agent (b) in an aqueous medium containing a base.

Further in accordance with the present invention, the coating composition can include a fine powder of a carboxyl group-containing resin dispersed therein to further improve sag without adversely affecting other performance. be able to.

The coating composition of the present invention can be used as an intermediate coating layer in the coating of, for example, automobile bodies to form a composite coating film on the surface of an article to be coated. The method comprises coating the coating composition of the present invention on the electrodeposition coating layer after curing or before curing on the surface of the object to be coated, and then baking and curing the intermediate coating layer or the electrodeposition coating layer at the same time. Forming an overcoat layer thereon. The overcoat layer preferably comprises a colored base coat and a clear coat applied thereon, and may be water-based or solvent-based. The overcoat layer is also preferably formed by applying a clear coat in a wet-on-wet manner on the base coat and baking and curing both of them at the same time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As is well known, polyester resins are produced by condensing polyhydric carboxylic acids and polyhydric alcohols as essential ingredients. Other reaction components can include minor proportions of monocarboxylic acids, hydroxycarboxylic acids, lactones, etc., and alkyd resins include drying oils or semi-drying oils and their fatty acids.

The polyester resin of the present invention has a content of 10 to 60%, preferably 2%, based on the total weight of all reaction components.
It is preferable to contain 0 to 50%, particularly 30 to 40% of aromatic polycarboxylic acid. Examples thereof are phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, pyromellitic dianhydride, but isophthalic acid, terephthalic acid, trimellitic anhydride are preferred. . If too much is used, the viscosity of the resin will increase during water solubilization or dispersion.

As the remaining acid component, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, 1,4- and 1,3-cyclohexanedicarboxylic acid, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, azelaic acid, etc. There is. As mentioned previously, small proportions of hydroxycarboxylic acids such as 4-hydroxybenzoic acid, hydroxypivalic acid, 12-hydroxystearic acid and the like, and monocarboxylic acids such as benzoic acid, t-butylbenzoic acid and the like may also be included.

The polyester resin of the present invention contains, as a polyhydric alcohol component, 1 to 30%, preferably 2 to 20%, and especially 3 to 15% of a hydroxyl group-terminated polyalkadiene diol alone, based on the total amount of all reaction components. It must contain hydrogenates alone or in mixtures. These diols are derived from conjugated alkadiene oligomers or polymers with a degree of polymerization of 5 to 50. The molecular weight is 1,
It is preferably in the range of 000 to 4,000, particularly 1,500 to 3,000. 1,4-polyisoprene diol, 1,4- and 1,2-polybutadiene diol, hydrogenated products thereof are preferred. As a commercial product, Epol (hydrogenated polyisoprene diol, molecular weight 186
0, average degree of polymerization 26, Idemitsu Petrochemical Co., Ltd., PIP
(Polyisoprene diol, molecular weight 2,2000, average degree of polymerization 34, manufactured by Idemitsu Petrochemical Co., Ltd.), Polytail HA
(Hydrogenated polybutadiene diol, molecular weight 2,200,
Average degree of polymerization 39, Mitsubishi Kasei Co., Ltd., Polytail H
(Hydrogenated polybutadiene diol, molecular weight 2,350,
Average degree of polymerization 42, manufactured by Mitsubishi Kasei Co., Ltd., R-45H
T (polybutadiene diol, molecular weight 2,270, average degree of polymerization 42, manufactured by Idemitsu Petrochemical Co., Ltd.) and the like. The use of these diols as part of the polyhydric alcohol component results in high molecular weight polyester resins that give relatively low viscosities at high degrees of neutralization. However, if it is used too much, the water dispersibility is lowered and a satisfactory coating hardness cannot be obtained.

As the remaining polyhydric alcohol component, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol and 2,2- Diethyl-1,3-propanediol, neopentyl glycol, 1,9-nonanediol, 1,4-cyclohexanedimethanol, hydroxypivalic acid neopentyl glycol ester, 2-butyl-2-ethyl-1,3
-Propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethylpentanediol, hydrogenated bisphenol A and other diols, and trimethylolpropane, trimethylolethane, glycerin, pentaerythritol and other three diols. There are polyols with a valency or higher.

In the case of alkyd resins, up to 30%, preferably up to 25%, especially 10 to 10% of the total weight of all reaction components.
It must contain 20% of fatty acids having 6 or more carbon atoms or fats and oils containing them. Examples of these fats and oils components are castor oil, linseed oil, dehydrated castor oil, tung oil, safflower oil, soybean oil, tall oil, coconut oil, palm kernel oil and their fatty acids. Palm oil and palm kernel oil are preferred.

As a reaction component other than the above, Cardura E
There are monoepoxide compounds such as (trade name: manufactured by Ciel Kagaku) and lactones. Lactones form ring-opening additions to the polyester chains of polyhydric carboxylic acids and polyhydric alcohols to themselves form polyester chains. Examples thereof include β-propiolactone, dimethylpropiolactone, butyrolactone, γ-valerolactone, ε-caprolactone, γ-caprolactone, γ-caprylolactone, crotlactone, δ-valerolactone, and δ-caprolactone. However, ε-caprolactone is preferred. Its amount is 3 to 30%, preferably 5 to 20%, in particular 7 to 15% of the total weight of all reaction components. Addition of lactone improves chipping resistance.

For the synthesis of polyester, the above reaction components are used in a conventional manner in a nitrogen stream at, for example, 150 to 250 ° C. and 4-1.
It can be performed by heating for 0 hours and condensation. In that case, as the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used. The reaction components may be added all at once, or may be added in several batches.

The molar ratio of the reaction components and the reaction conditions are such that the polyester resin obtained has an acid value of 5 to 150, preferably 10 to 100, and a hydroxyl value of 30 to 250, preferably 5.
0-150, weight average molecular weight 10,000-200,
It should be adjusted to reach 000, preferably 25,000 to 160,000.

The polyester resin of the present invention can be dissolved or dispersed in an aqueous medium containing 0.3 to 1.2 equivalents, preferably 0.5 to 1.0 equivalents of a base with respect to the acid value of the resin. Examples of the base include inorganic bases such as alkali metal hydroxides and aqueous ammonia, and methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropylamine, diisopropylamine, diethylenetriamine, triethylenetetramine, monoethanolamine,
Diethanolamine, 2-amino-2-methylpropanol, morpholine, N-methylmorpholine, N-ethylmorpholine, piperazine, dimethylethanolamine,
There are amines such as diethylethanolamine and dimethyldodecylamine. Triethylamine, dimethylethanolamine and diethylethanolamine are preferred. Excessive base is not preferable because it accelerates the hydrolysis of the resin during storage.

The Japanese Patent Publication No. 3-21227 of the applicant,
A method for forming a composite coating film using an aqueous coating material in which a powder resin is dispersed as an intermediate coating layer and / or a chipping sealer is disclosed. The coating composition of the present invention can also contain a resin containing a carboxyl group, for example, a fine powder of an acrylic resin or a polyester resin containing a carboxyl group. The particle size is 3 to 60 μ, preferably 5 to 2
5μ, acid value 15-300, preferably 30-1
00. By dispersing the resin fine particles, not only can the coating be made high solid, but also the sag limiting film thickness can be improved by the structural viscosity effect. The addition amount is 2:98 to 40: 6 by weight ratio to the polyester resin.
0, preferably 5:95 to 30:70, especially 10:90
~ 25: 75. Adding too much will impair the flowability of the paint.

The coating composition of the present invention must contain a crosslinking agent that reacts with the polyester resin alone or both the polyester resin and the resin fine powder. Examples of such crosslinking agents are epoxy resins, melamine resins, triglycidyl isocyanurate, dicyandiamide and the like. In the case of the alkyd resin, a drier of cobalt naphthenate, lead naphthenate, zinc naphthenate or the like may be used. Melamine resins are preferred. The amount depends on the type of the cross-linking agent, but in the case of a melamine resin, it is generally in the range of polyester resin: melamine resin = 6: 4 to 8: 2 as a solid content. The melamine resin is typically a methylolated melamine which is a condensate of melamine and formaldehyde, and some or all of its methylol groups etherified with alcohols such as methanol, ethanol, n-butanol and isobutanol. is there. Sulfonic acids such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, and dinonylnaphthalenesulfonic acid, and salts of these sulfonic acids with organic amines that dissociate at the baking temperature of the coating film can be used as a catalyst.

The coating composition is prepared by dissolving or dispersing a polyester resin in an aqueous medium containing a base to produce an aqueous varnish, and adding a crosslinking agent thereto. The coating composition in which the resin powder is dispersed is prepared by preparing an aqueous varnish of polyester resin by using the whole amount or a part of the base, and adding the resin fine powder and the remaining base to the mixture and heating or stirring to disperse the polyester resin. The resin powder and the base are all added to the aqueous medium at the same time, and the mixture is heated and stirred for dispersion. At that time, the base neutralizes the polyester resin and the resin powder to a degree of neutralization of 30 to 120%, particularly 50 to 100.
It is preferably used in an amount that neutralizes to%. The heating temperature is preferably 35 to 95 ° C. When these conditions are followed, the resin powder can be stably dispersed as primary particles.

The aqueous medium is usually ion-exchanged water, but it may optionally contain a small amount of a water-miscible organic solvent. Examples are diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monomethyl ether, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol. , Dimethylformamide, N
-Methylpyrrolidone and the like.

The coating composition of the present invention may contain conventional pigments. Examples are titanium dioxide, white lead, zinc white,
Zinc sulfide, graphite, carbon black, yellow iron oxide, red iron oxide, phthalocyaning blue, phthalocyanine green, quinacridone, indanthrone, isoindolinone, perylene, anthrapyrimidine, benzimidazolone, cadmium yellow, cadmium red,
Coloring and rust preventive pigments such as chrome yellow and diketopyrrolopyrrole, and extender pigments such as calcium carbonate, barium sulfate, silicic acid type, silicate type and aluminum hydrate type. The pigment is prepared by using a part of the polyester resin aqueous varnish dissolved or dispersed in an aqueous medium containing a base to form a pigment paste, and the pigment paste is added to the rest of the aqueous varnish or the resin powder-dispersed aqueous varnish. The pigment content of the coating composition is expressed as a weight ratio of pigment / resin solid content in the coating composition, and is usually 0.01 / 1 to 1/1, preferably 0.03 / 1 to 0.9 /. It is within the range of 1.

The coating composition of the present invention is applied onto the electrodeposition coating layer after curing or before curing, and the intermediate coating layer or both of it and the electrodeposition layer are baked and cured at the same time, and an overcoat layer is formed thereon. It is suitable as an intermediate coating used for forming the formed composite coating film. Especially when applied to the coating of automobile bodies, when coating on the electrodeposition coating layer to a film thickness to obtain satisfactory chipping resistance, it does not cause sagging, pinholes, dents, etc. Excellent composite coating can be obtained. The overcoat layer is usually composed of a base coat layer and a clear coat layer, and can have a metallic or solid color finish depending on the type of pigment contained in the base coat layer. The base coat and the clear coat may be water-based or solvent-based, and it is preferable that the clear coat is coated on the base coat in a wet-on-wet manner and both are baked and cured at the same time. Such coating methods and coatings used are well known and do not themselves constitute a part of the invention and need no further explanation.

The invention is illustrated by the following examples. "%" In the examples is based on weight.

[0025]

155 parts by weight of coconut oil, 248 parts by weight of trimethylolpropane, and dibutyltin oxide were added to a reaction vessel having a heating device, a stirrer, a nitrogen introducing pipe and a fractionating tower.
After 7 parts by weight were charged, heating was started under dry nitrogen to melt the raw material, and then the temperature was gradually raised to 210 ° C., transesterification was performed, and the mixture was cooled. Next, 267 parts by weight of isophthalic acid, 59 parts by weight of adipic acid, 33 parts by weight of neopentyl glycol, and 41 parts by weight of epol (hydrogenated polyisoprene diol, molecular weight = 1860, average repetition number n = 26, manufactured by Idemitsu Petrochemical Co., Ltd.) Was added and the temperature was gradually raised to 220 ° C. to carry out a dehydration esterification reaction. After dehydration esterification to a resin acid value of 10, the mixture was cooled to 150 ° C., 40 parts by weight of trimellitic anhydride was added to react to a resin acid value of 40, cooled to 140 ° C., and ε-caprolactone was further added to 1 The reaction was carried out for a time and the reaction was completed. Solvesso # 150 (aromatic hydrocarbon solvent,
75 parts by weight of Esso Chemical Co., Ltd., butyl cellosolve 7
5 parts by weight was added to obtain a polyester resin varnish I having a resin solid content of 83%. The resulting polyester resin had a hydroxyl value of 137, an acid value of 37, and a number average molecular weight of 2850 (converted to polystyrene).

Obtained polyester resin varnish I, 10
An aqueous polyester resin varnish A was obtained by adding 3.9 parts by weight of dimethylethanolamine (0.8 equivalents of the total amount of carboxyl groups) to 0 parts by weight and adding 103.6 parts by weight of ion-exchanged water to a mixture. The resulting aqueous polyester resin varnish showed good water dispersibility. Nonvolatile content 40%

Synthetic Examples 2 to 6 Polyester resin varnishes II to VI and aqueous polyester resin varnishes BF were prepared in the same manner as in Synthetic Example 1 except that the raw materials were changed as follows. The properties of the resin and varnish are shown in Tables 1 and 2.

[0029] * Polyisoprene diol, molecular weight = 2,400, average degree of polymerization 34, manufactured by Idemitsu Petrochemical Co., Ltd.

[0030] * Synthesis example 3: Polytail HA (hydrogenated polybutadiene diol, molecular weight = 2,200, average degree of polymerization 39, manufactured by Mitsubishi Kasei Co., Ltd.) * Synthesis example 4: Polytail H (hydrogenated polybutadiene diol, molecular weight 2,350, Average degree of polymerization 42, manufactured by Mitsubishi Kasei Co., Ltd. * Synthesis example 5: R-45HT (polybutadiene diol,
Molecular weight 2,270, average degree of polymerization 42, manufactured by Idemitsu Petrochemical Co., Ltd.

[0031]

[0032]

[Table 1]

[0033]

[Table 2]

Synthetic Examples 7 to 10 (Comparative Resins) The composition of the raw materials was changed as shown in Table 3 and polyester resin varnishes VII to X and aqueous polyester resin varnishes G to J were prepared in the same manner as in Synthetic Example 1. . The properties of the resin and varnish are shown in Table 3 and Table 4, respectively.

[0035]

[Table 3]

[0036]

[Table 4]

Examples 1 to 6 and Comparative Examples 1 to 3 Pigment Dispersion Pastes 30 parts by weight of ion-exchanged water and 130 parts by weight of rutile titanium dioxide are added to 100 parts by weight of the aqueous polyester varnishes A to J shown in Tables 2 and 4, respectively. After premixing, a glass bead medium was added in a paint conditioner, and the mixture was mixed and dispersed at room temperature for 1 hour to obtain a pigment dispersion paste having a particle size of 5 μm or less and a nonvolatile content of 65.4%.

Coating Composition To the aqueous polyester varnishes A to J shown in Tables 2 and 4, a pigment paste prepared from the same aqueous polyester varnish was added, and further hexamethoxymethylol melamine and p-toluenesulfonic acid were added to the coating composition. Was prepared.

Each coating composition was applied to Ford Cup No. 4 was diluted with ion-exchanged water up to 30 seconds / 20 ° C. and the performance was evaluated. The results are shown in Table 5.

Evaluation method 1) Gloss: A paint is applied on a tin plate and then at 150 ° C. for 30 days.
It was baked for minutes and evaluated according to JIS K-5400. 2) Pencil hardness: Same as above. 3) Solvent resistance: The cured coating film was rubbed back and forth 10 times with gauze containing xylene, and the state of the coating film was observed. 4) Pin limit film thickness: A 10 cm × 30 cm steel plate is spray-painted so that the thickness of the thick film portion is about 70 μ,
After keeping the coated plate aqueous in a coating booth (25 ° C., 75% RH), it is baked and cured at 150 ° C. for 30 minutes. At this time, the maximum film thickness without pinhole defects is defined as the pin limit. 5) Penetration property: Spray coating (about 35 μ) on a tin plate of 30 cm × 40 cm, and after about 1 minute, the dent state when the same paint is dust coated is visually evaluated. ○: good, △: somewhat bad, ×: bad 6) chipping resistance: zinc phosphate treated 0.8m thick
Cationic electrodeposition paint on Nippon Steel (Nippon Paint Co., Ltd.)
Manufactured by Power Top UP-50) by electrodeposition coating so that the dry film thickness becomes about 25μ, and baked at 160 ° C. for 30 minutes, and then the paints of each Example and Comparative Example are adjusted so that the dry film thickness becomes about 35μ. It was spray coated and baked at 150 ° C for 30 minutes. Immediately after cooling, a base paint (Olga TO-521 manufactured by Nippon Paint Co., Ltd.) was spray-coated so that the dry film thickness was about 16 μ, and after setting for about 7 minutes, an acrylic melamine-based clear paint (Nippon Paint Co., Ltd.) Olga TO-563) manufactured by Spray Co., Ltd. was spray-coated so that the dry film thickness was about 40 μm, and baked at 140 ° C. for 20 minutes to prepare a test coated plate. In a sample holder of a stepping stone tester (manufactured by Suga Tester Co., Ltd.), a coating film cooled to -30 ° C has a stone entry angle of 6
Attach it so that it is at 0 °, and use 100g of No. 7 crushed stone for 3k
It is jetted with an air pressure of g / cm ^{2 so} that the crushed stones collide with the coated plate. The degree (number and size) of peeling scratches at that time is evaluated. ◎: Almost no peeling damage, ○: There is a small amount of peeling, △: Some peeling damage, ×: Peeling damage on the entire surface 7) Dripping limit film thickness: 10 cm × 30 cm having a hole with a diameter of 5 mm in the longitudinal center Spray thick film on the steel plate to a thickness of approx.
After holding the coated plate vertically in 5 ℃, 70% RH,
Bake and cure at 0 ° C. for 30 minutes. At this time, the maximum film thickness without sagging from the hole is defined as the sag limit.

[0041]

[Table 5]

Examples 7 to 13 and Comparative Examples 4 to 6 As resin fine powder, acid value 53, Tg 109 ° C., molecular weight 3
A fine powder (particle size: 45 μm or less) of 800 polyester resin (Findick M6107 manufactured by Dainippon Ink and Chemicals, Inc.) was used to prepare an aqueous coating composition according to the formulation shown in Table 6. The above resin fine powder was gradually added to each of the aqueous polyester resin varnishes A to J while heating and stirring,
The mixture was maintained at 70 ° C. for 15 minutes and dispersed by stirring to obtain a stable dispersion liquid. Into this dispersion, Examples 1 to 6 and Comparative Examples 1 to 1
The pigment paste prepared from the same aqueous polyester resin varnish used in 3 was added, and further hexamethoxymethylol melamine and p-toluenesulfonic acid were added and mixed to prepare a coating composition. Each of the obtained coating materials was evaluated by the same evaluation method as in Examples 1 to 6 and Comparative Examples 1 to 3.
The results are shown in Table 6.

[0043]

[Table 6]

Example 14 A 0.8 mm thick dull steel sheet treated with zinc phosphate was coated on a cationic electrodeposition coating (Power Top PU manufactured by Nippon Paint Co., Ltd.).
-50) is electrodeposited to a dry film thickness of about 25μ,
After washing with water and preheating, the water-based paint of Example 7 was dried to a film thickness of about 3
It was spray-coated so as to have a thickness of 5 μm and baked at 150 ° C. for 30 minutes. Next, adjust the viscosity of the base paint of the following formulation with a Ford cup # 4 for 14 seconds, apply two stages with an air spray to a dry film thickness of 15μ, and after leaving for 7 minutes,
The viscosity of the clear paint with the following composition was adjusted with a Ford cup # 4 for 20 seconds, and wet-on-wet coating was applied to the base coating film by air spraying so that the dry film thickness was 40μ. It was baked and cured for a minute. After baking, the coating film is free from defects such as sagging and pinholes.
The gloss was 95 or more, and the flowability and sharpness were also good.

Base paint formulation Alpaste 7160N (Toyo Aluminum Co., Ltd. 10.9 parts aluminum flake paste, aluminum flake content 65%) Almatex NT-U-448 (Mitsui Toatsu Chemicals, Inc. 66.9) Part thermosetting acrylic resin varnish, solid content 48%) U-VAN 20N-60 (Mitsui Toatsu Chemicals, Inc. 13.5 parts melamine resin varnish, solid content 60%) Toluene 6.4 parts n-butanol 2.0 Part triethylamine 0.5 part

Clear paint formulation DIANAL HR-554 (manufactured by Mitsubishi Rayon Co., Ltd., 58.3 parts, thermosetting acrylic resin varnish, solid content 60%) ACR-461 (manufactured by Nippon Paint Co., Ltd., 63.6 parts, heat) Curable acrylic resin varnish, solid content 55%) U-VAN 20N-60 50.0 parts Tinuvin 900 (UV absorber made by Ciba-Geigy) 2.0 parts SANOL LS-292 (manufactured by Sansha Machine Gosei Co., Ltd. 1.0 part) Antioxidant) n-Butanol 1.3 parts Solvesso 100 5.0 parts

Example 15 The solvent-based base paint of Example 14 was changed to an aqueous base paint having the following composition, the viscosity was adjusted to 30 seconds with a Ford cup # 4, and a dry film thickness of 15 μm was obtained by air spraying.
A composite coating film was obtained by the same procedure as in Example 14, except that the same solvent type clear coating material was applied after stage coating and preheating at 80 ° C. for 5 minutes. The coating film after baking had no defects such as sagging and pinholes, a gloss of 90 or more, and good flowability and sharpness.

Base paint formulation Alpaste 7160N 15 parts Cymel 303 (Mitsui Toatsu Chemical Co., Ltd. 30 parts melamine resin) Phosphorex A-180L (Sakai Chemical Industry Co., Ltd. 2 parts isostearyl phosphate) Aqueous acrylic Resin varnish * 112 parts Urethane emulsion (solid content 33%, acid value 16.2) 43 parts * Solid content 50 obtained by polymerizing the following monomer mixture
%, Number average molecular weight 12,000, hydroxyl value 70, acid value 5
Aqueous varnish of acrylamide-containing acrylic resin of 8.

Ethylene glycol monobutyl ether 76 parts Styrene 15 parts Methyl methacrylate 63 parts 2-Hydroxyethyl methacrylate 48 parts n-Butyl acrylate 117 parts Methacrylic acid 27 parts Acrylamide 30 parts Azobisbutyronitrile 3 parts Dimethylethanolamine 28 200 parts of deionized water

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // C08G 63/48 NNZ 63/52 NNT 63/60 NPS (72) Inventor Yasuhiro Shibata Neyagawa, Osaka 19-17 Ikedanaka-cho, Ichi, Japan Paint Co., Ltd.

Claims (11)

[Claims] 1. (a) A hydroxyl group-terminated polyalkadiene diol alone having an average degree of polymerization of 5 to 50, a hydrogenated polyalkadiene diol alone, based on the total amount of all reaction components.
Or containing 1 to 30% by weight of a mixture thereof and having an acid value of 5 to 15
A thermosetting aqueous coating composition obtained by dissolving or dispersing a polyester resin having a hydroxyl value of 30 to 250 and (b) a crosslinking agent in an aqueous medium containing a base. 2. The thermosetting resin according to claim 1, wherein the polyester resin is an alkyd resin containing a fatty acid having 6 or more carbon atoms up to 30% by weight or an oil or fat containing the same, based on the total amount of all reaction components. Water-based coating composition. 3. The thermosetting aqueous coating composition according to claim 1, wherein the polyester resin contains 3 to 30% by weight of a cyclic lactone based on the total amount of all reaction components. 4. The thermosetting water-borne coating composition according to claim 1, wherein the polyester resin contains 10 to 60% by weight of an aromatic polyvalent carboxylic acid based on the total amount of all reaction components. Composition. 5. The thermosetting aqueous coating composition according to claim 1, wherein the polyester resin has a weight average molecular weight of 10,000 to 200,000. 6. The number average molecular weight of the polyalkadiene diol and hydrogenated polyalkadiene diol is 1,000.
The thermosetting water-borne coating composition according to any one of claims 1 to 5, which is a polyisoprene diol, a polybutadiene diol or a hydrogenated product thereof of about 4,000 to 4,000. 7. The thermosetting aqueous solution according to claim 1, wherein the cross-linking agent is a melamine resin, and the ratio thereof is a solid content of polyester resin: melamine resin weight ratio = 6: 4 to 8: 2. Coating composition. 8. The thermosetting aqueous coating composition according to claim 1, which contains fine powder of a carboxyl group-containing resin dispersed in the coating composition. 9. A fine powder of the carboxyl group-containing resin,
The weight ratio to the polyester resin is 2: 98-4.
The thermosetting water-borne coating composition according to claim 8, which is contained at a ratio of 0:60. 10. The thermosetting aqueous coating composition according to claim 1, further comprising a pigment. 11. A method for forming a composite coating film, which comprises coating a composite layer consisting of an electrodeposition coating layer, an intermediate coating layer and an overcoat layer on the surface of an object to be coated, and curing the composite coating layer. 1
1 to 10 is applied onto the electrodeposition coating layer after curing or before curing, and the intermediate coating layer or the electrodeposition coating layer and the intermediate coating layer are baked and cured at the same time, and then the top coating is applied. A method for forming a composite coating film, which comprises forming a layer.