JPH07207227A - One-component coating composition with decreased yellowing due to baking - Google Patents

Abstract

PURPOSE:To obtain a coating compsn. which does not yellow under heating, etc. CONSTITUTION:This compsn. contains a thermally dissociatable blocked polyisocyanate, a polyhydroxy compd., and at least two compds. selected from at least two different groups of the following groups: one consisting of compds. having a group of formula I or II (wherein R<1> And R<2> are the same or different, optionally substd. alkyl groups provided they may combine with each other to form a ring), one consisting of divalent-tin compds., and one consisting of phosphites.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-part coating composition containing a block polyisocyanate in which yellowing of a coating film during baking is extremely reduced.

[0002]

2. Description of the Related Art In recent years, stains may be formed on a coating film such as an automobile top coat due to environmental factors, and the appearance may be significantly impaired. The mechanism of stain formation is, for example, Abo et al.
(10), 605-611 (1992)], the decomposition of melamine cross-linking points. Therefore, in order to fundamentally cope with this problem, the best method is to use a crosslinking agent other than the melamine resin. There are many proposals for a crosslinking agent relating to this, for example, JP-A-2-242867, JP-A-3-172368, and JP-A-4-407.
No. 9 method, JP-A-5-239406, and the like.

[0003]

A coating system using a block isocyanate as a curing agent has excellent chemical resistance, durability, mechanical properties of a coating film, and the like, so that it is expected to be a post-melamine resin, but it is cured at a high temperature. Sometimes 160
Yellowing of the coating film is unavoidable when it is cured at a temperature of ℃ or more, and its use is markedly limited particularly in coatings such as automobile top coats where the appearance is important.

[0004]

The present inventors have found that the above problems can be solved by containing a specific compound or a specific group, and have reached the present invention. That is, the present invention is selected from at least two different groups from the group of compounds containing the group represented by the general formula (1) or the general formula (2), the group of divalent tin compounds and the group of phosphite ester compounds. One-part coating composition containing two or more compounds, a thermally dissociable block polyisocyanate and a polyvalent hydroxy compound, and a group of compounds containing a group represented by the general formula (1), a group of divalent tin compounds and a sub-group. The present invention relates to a one-pack coating composition containing at least one compound selected from the group of phosphoric acid ester compounds, a thermally dissociable block polyisocyanate having a group represented by the general formula (2), and a polyvalent hydroxy compound.

[0005]

[Chemical 5]

[0006]

[Chemical 6]

The present invention will be described in more detail below. The heat dissociable block polyisocyanate used in the present invention can be obtained by a known reaction between a polyisocyanate and a blocking agent. Examples of the polyisocyanate include isocyanurate-modified polyisocyanate, buret-modified polyisocyanate, and urethane-modified polyisocyanate. Preferably, excellent weather resistance, heat resistance,
Isocyanurate-modified polyisocyanate. When synthesizing an isocyanurate-modified polyisocyanate, for example, JP-A-57-47321 and JP-A-61-11 are used.
It may be modified with a hydroxyl compound as in JP 1371. Examples of the hydroxyl compound used for modification include methanol, ethanol, isopropanol, monohydroxyl compounds such as phenol, ethylene glycol, propylene glycol, 1,3-butanediol, pentanediol, hexanediol, cyclohexanediol, neopentyl glycol, Two
There are dihydroxyl compounds such as 2,4-trimethyl 1,3-pentanediol. These may be used alone or in combination of two or more. Also, Japanese Patent Application No. 5-0241
A polyhydric alcohol having a valence of 3 or more exemplified by 51 may be used.

These polyisocyanates can be derived from aliphatic or cycloaliphatic diisocyanates. The aliphatic diisocyanate has 4 to 30 carbon atoms, and the alicyclic diisocyanate has 8 to 30 carbon atoms.
Preferred are, for example, 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,
2,4 (or 2,4,4) -trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanatomethyl) -cyclohexane, 4,4 Examples thereof include'-dicyclohexyl methane diisocyanate, xylylene diisocyanate, and tetramethyl xylene diisocyanate. Among them, 1,6-hexamethylene diisocyanate (hereinafter referred to as HMDI) and isophorone diisocyanate (hereinafter referred to as IPDI) are preferable from the viewpoint of weather resistance and industrial availability. These may be used alone or in combination of two or more.

Isocyanurate-modified polyisocyanates can be obtained by using the above-mentioned isocyanates. A catalyst is usually used for the isocyanurate-forming reaction.
The catalyst used here is generally preferably basic, and examples thereof include quaternary ammonium salts, organic weak acid salts thereof, alkyl metal salts of alkylcarboxylic acids, metal alcoholates, and aminosilyl group-containing compounds. The catalyst concentration is usually 10 pp with respect to the isocyanate compound.
It is selected from the range of m to 1.0%.

The reaction may or may not use a solvent. If a solvent is used, a solvent inert to the isocyanate group should be used. The reaction temperature is usually 20-
The temperature is 160 ° C, preferably 40 to 130 ° C. The reaction end point varies depending on the polyhydric alcohol used, but the yield is about 3
It becomes 0% or more. When the reaction reaches a desired yield, the catalyst is deactivated by, for example, sulfonic acid, phosphoric acid, phosphoric acid ester or the like to stop the reaction.

Unreacted diisocyanate and solvent can be removed to obtain a polyisocyanate having an isocyanurate structure. Examples of the blocking agent of the present invention for obtaining the heat dissociable block polyisocyanate include, for example, phenol type, active methylene, mercaptan type, acid amide type, acid imide type, imidazole type, urea type, oxime type, amine type, imide There are system compounds and the like, and these may be used alone or in combination. Examples of more specific blocking agents are shown below. (1) Phenol-based; phenol, cresol, ethylphenol, butylphenol, nonylphenol, dinonylphenol, styrenated phenol, oxybenzoic acid ester, etc. (2) Active methylene-based; dimethyl malonate, diethyl malonate, methyl acetoacetate, acetoacetic acid Ethyl, acetylacetone, etc. (3) Mercaptan type; butyl mercaptan, dodecyl mercaptan, etc. (4) Acid amide type; Acetanilide, acetic acid amide, ε-
Caprolactam, δ-valerolactam, γ-butyrolactam, etc. (5) Acid imide type; succinimide, maleic imide, etc. (6) Imidazole type; imidazole, 2-methylimidazole, etc. (7) Urea type; urea, thiourea, Ethylene urea, etc. (8) Oximes; formaldoxime, acetoaldoxime, acetoxime, methylethylketoxime, cyclohexanone oxime, etc. (9) Amines; diphenylamine, aniline, carbazole, etc. (10) Imines; ethyleneimine, polyethyleneimine, etc. (11) Bisulfite: sodium bisulfite, etc. Of these, phenols, oximes, and acid amides are preferable, and nonylphenol, styrenated phenol, oxybenzoate, acetoxime, methylethylketoxime, and ε are particularly preferable. Caprolactam is preferred.

A heat dissociable block polyisocyanate can be obtained by reacting the above blocking agent with polyisocyanate. The reaction between the polyisocyanate and the blocking agent can be carried out with or without the presence of a solvent.
When using a solvent, it is necessary to use a solvent which is inactive to the isocyanate group.

In the blocking reaction, an organic metal salt of tin, zinc, lead or the like and a tertiary amine may be used as a catalyst. The reaction can be generally carried out at -20 to 150 ° C, preferably 0 to 100 ° C. If the temperature is 100 ° C. or higher, a side reaction may occur. On the other hand, if the temperature is too low, the reaction rate becomes slow, which is disadvantageous.

The compound containing a group represented by the general formula (1) used in the present invention includes, for example, a reaction of a carboxylic acid chloride with an N, N-disubstituted hydrazine, or a reaction of a carboxylic acid ester with an N, N-diazine. It is obtained by a transesterification reaction with a substituted hydrazine. In addition, the general formula (2)
The compound containing a group represented by is obtained, for example, by reacting an isocyanate compound with an N, N-disubstituted hydrazine. Examples of the N, N-disubstituted hydrazine include N, N-dimethylhydrazine, N, N-diethylhydrazine, N, N-dipropylhydrazine, N, N-diisopropylhydrazine, N, N-distearylhydrazine and N-. Methyl-N-ethylhydrazine, N-methyl-
N-isopropylhydrazine, N-methyl-N-benzylhydrazine, N, N-di (β-hydroxyethyl)-
Examples thereof include hydrazine, but the total number of carbon atoms is preferably up to about 20. If the number of carbon atoms is too large, the proportion of hydrazine residues will be large, so that not only a large amount of compound is required for stabilization, but also the compatibility is lowered. Preferred is hydrazine substituted with an alkyl group having 4 or less carbon atoms. Particularly preferred is N, N-dimethylhydrazine. These N, N-disubstituted hydrazines may be used alone or in combination of two or more.

Examples of the isocyanate compound in this case include 1,4-tetramethylene diisocyanate,
1,5-pentamethylene diisocyanate, HMDI,
2,2,4 (or 2,4,4) -trimethyl-1,6
-Hexamethylene diisocyanate, lysine diisocyanate, IPDI, 1,3-bis (isocyanatomethyl) -cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, xylylene diisocyanate,
Aliphatic or alicyclic diisocyanate such as tetramethylxylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene diisocyanate And aromatic diisocyanates such as, and polyisocyanates derived from these diisocyanates, n-butyl isocyanate, n-hexyl isocyanate, n-octyl isocyanate, monoisocyanates such as phenyl isocyanate. be able to. Polyisocyanate derived from diisocyanate, isocyanurate-modified polyisocyanate, buret-modified polyisocyanate, urethane-modified polyisocyanate similar to the polyisocyanate used in the production of the heat-dissociable block polyisocyanate described above. Etc.

Of these isocyanate compounds, aliphatic or alicyclic diisocyanates and polyisocyanates derived therefrom are preferred, and H is more preferred.
MDI or IPDI and polyisocyanates derived therefrom. You may use together 2 or more types of these isocyanate compounds. The reaction between the isocyanate compound and the N, N-disubstituted hydrazine can be carried out with or without a solvent. When using a solvent, it is necessary to use a solvent which is inert to isocyanate. The reaction can be generally carried out at -20 to 150 ° C, preferably 0 to 100 ° C. If the temperature is 100 ° C. or higher, a side reaction may occur. On the other hand, if the temperature is too low, the reaction rate becomes slow, which is disadvantageous.

When the isocyanate compound is a di- or polyisocyanate, all of the isocyanate groups may form the group represented by the general formula (2) or may form a part thereof. When only a part of them forms a group represented by the general formula (2), the remaining isocyanate group may be blocked with an active hydrogen compound. Examples of the active hydrogen compound include alcohols such as methanol, ethanol, n-butanol, isobutanol, n-propyl alcohol and isopropyl alcohol, in addition to the blocking agents exemplified for obtaining the heat dissociable block polyisocyanate. You can

Examples of such a compound include HN-130, HN-150 and HN-30 manufactured by Nippon Hydrazine Industry.
There are 0P etc. Examples of the phosphite compound used in the present invention include dilauryl hydrogen phosphite as the phosphite dialkyl ester, and diphenyl hydrogen phosphite as the phosphite diaryl ester as the phosphite trialkyl ester. Is, for example, triethyl phosphite, tris (2 ethylhexyl) phosphite, tridodecyl phosphite,
Tris (tridecyl) phosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, trilauryl trithiophosphite, bis (tridecyl) pentaerythritol diphosphite, etc. Phyto, tris (nonylphenyl) phosphite, and the like, as phosphorous acid trialkylaryl esters, for example, diphenylmono (2-ethylhexyl) phosphite, diphenylmonodecylphosphite, diphenylmono (tridecyl) phosphite, tetraphenyldipropyleneglycol. Diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, tetra (tridecyl) -4,
4'-isopropylidenediphenyl phosphite, bis (nonylphenol) pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite and the like can be mentioned. Two or more of these may be used in combination.

The divalent tin compound used in the present invention may be any divalent tin compound, including organic compounds and inorganic compounds. Examples of the divalent organic compound include stannous carboxylate compounds, stannous sulfonates, stannous alkyl compounds, stannous alkyl ether compounds, and the like. Examples of the stannous carboxylate compound include stannous formate, stannous acetate, stannous propionate, stannous butyrate,
Stannous isobutyrate, stannous valerate, stannous isovalerate, 2
Stannous methylbutanoate, stannous pivalate, stannous hexanoate, stannous 4-methylpentanoate, stannous 2-ethylbutanoate, stannous 2,2-dimethylbutanoate, stannous heptanoate Stannous, stannous 2-ethylhexanoate, stannous octoate, stannous nonanoate, stannous decanoate, stannous undecanoate, stannous dodecanoate, stannous tetradecanoate,
Stannous hexadecanoate, stannous heptadecanoate, stannous octadecanoate, stannous eicosanate, stannous docosanoate, stannous hexacosanoate, stannous triacontanate,
Stannous acrylate, stannous crotonic acid, stannous isocrotonic acid, stannous 3-butenoate, stannous methacrylate, stannous angelic acid, stannous oxalate, stannous malonate,
There are stannous succinate, stannous glutarate, stannous adipate, stannous suberate, stannous azelate, stannous sebacate, stannous maleate and the like.

Examples of stannous sulfonate include stannous sulfamate. Examples of the alkyl stannous include diethyl tin, di-n-propyl tin, di-isopropyl tin, di-n-butyl tin, diisobutyl tin, di-n-butoxy tin, and diisobutoxy tin. Examples of the stannous alkyl ether include diethoxy tin, di n-propyl tin, diisopropyl tin, di n-propyl tin and diisopropyl tin.

As the inorganic compound of divalent tin, stannous chloride, stannous bromide, stannous iodide, stannous hydroxide, stannous sulfide, tin monohydrogen phosphate, tin dihydrogen phosphate, Examples include stannous sulfate and stannous oxide. Organic stannous is preferable, and stannous carboxylate is more preferable. In the present invention, two or more kinds selected from at least two different groups from the group of compounds containing a group represented by the general formula (1) or the general formula (2), the group of phosphite compounds and the group of divalent tin compounds. It is necessary to use the above compound in combination. However, as described above, when the group represented by the general formula (2) is bonded to the heat dissociable block polyisocyanate, which is another component of the composition of the present invention, one of the above compound groups is Two compounds may be used. The total addition amount of these is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the coating resin component.
Is. And the ratio between each compound group is from 1: 9
9: 1 is preferred. Outside of these ranges, the yellowing of the baked coating is not significantly reduced. In particular, the effect is greatest when at least one compound is selected from the above compound groups and used in combination. The total amount of selected compounds added in this case is 0.01 to 10% by weight, preferably 0.1 to 5% by weight. The ratio between compound groups is 0.1
It is 0.8: 0.1-0.8: 0.1-0.8.

Examples of polyhydric hydroxy compounds that can be used in the present invention include aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, epoxy resins, fluorine polyols and acrylic polyols. Specific examples of the aliphatic hydrocarbon polyols include, for example, end-hydroxylated polybutadiene and hydrogenated products thereof. Examples of the polyether polyols include polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to a single or mixture of polyhydric alcohols such as glycerin and propylene glycol, and a polytetraol. Polyethylene polyols obtained by reacting methylene glycols and alkylene oxides with polyfunctional compounds such as ethylenediamine and ethanolamine, and so-called polymer polyols obtained by polymerizing acrylamide and the like using these polyethers as a medium. Etc. are included.

As the polyester polyols, for example, a dibasic acid alone selected from the group of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid and terephthalic acid. Or a polyester polyol resin obtained by a condensation reaction of a mixture and a polyhydric alcohol selected from the group of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc., alone or in a mixture, and, for example, ε- Examples thereof include polycaprolactones obtained by ring-opening polymerization of caprolactone using a polyhydric alcohol.

The epoxy resins include, for example, novolac type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycol ether type, epoxy type of aliphatic unsaturated compound, epoxidized fatty acid ester type,
Examples thereof include polycarboxylic acid ester type, aminoglycidyl type, halogenated type, resorcin type epoxy resins, and resins obtained by modifying these epoxy resins with amino compounds, polyamide compounds and the like.

Examples of the fluorinated polyols are, for example, JP-A-57-34107 and JP-A-61-275311.
There are copolymers of fluoroolefin, cyclohexyl vinyl ether, hydroxyalkyl vinyl ether, monocarboxylic acid vinyl ester and the like disclosed in Japanese Patent Publication No. Acrylic polyols are obtained by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule with another monomer copolymerizable with the polymerizable monomer.
For example, acrylic acid esters having active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate,
Methacrylic acid-2-hydroxyethyl, methacrylic acid-
Methacrylic acid esters having active hydrogen such as 2-hydroxypropyl and 2-hydroxybutyl methacrylate,
Or a single or a selected from the group of (meth) acrylic acid esters having polyvalent active hydrogen such as acrylic acid monoesters or methacrylic acid monoesters of glycerin, acrylic acid monoesters or methacrylic acid monoesters of trimethylolpropane Mixtures and acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, -n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate,
-N-butyl methacrylate, isobutyl methacrylate,
Methacrylic acid-n-hexyl, cyclohexyl methacrylate, lauryl methacrylate, methacrylic acid esters such as glycidyl methacrylate, and further unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, acrylamide, if necessary. It is obtained by copolymerizing an unsaturated amide such as N-methylol acrylamide or diacetone acrylamide, and a homopolymer or a mixture selected from the group of other polymerizable monomers such as styrene, vinyltoluene, vinyl acetate and acrylonitrile. Further, JP-A-1-261409 and JP-A-3-6
Acrylic polyol resins obtained by copolymerizing the polymerizable UV-stable monomers exemplified in Japanese Patent No. 273 and the like are mentioned.

Among these polyols, acrylic polyols and polyester polyols having a hydroxyl value of 20 to 400 and a number average molecular weight of 1,000 to 50,000 are particularly preferable. The equivalent ratio of the blocked isocyanate group in the block polyisocyanate used in the present invention to the hydroxyl group in the polyol is determined by the required physical properties of the coating film. A melamine resin can also be used together. Examples of the melamine resin include hexamethoxymethylol melamine, methyl butylated melamine, and butylated melamine.

Various solvents and additives can be used depending on the intended use and purpose. Examples of the solvent include hydrocarbons such as benzene, toluene, xylene, cyclohexane, mineral spirit, and naphtha, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, esters such as ethyl acetate, -n-butyl acetate, and cellosolve acetate. It can be appropriately selected and used from the group of butanol, alcohols such as isopropyl alcohol, etc. according to the purpose and application. These solvents may be used alone or in combination of two or more.

If necessary, a curing accelerator, an antioxidant, an ultraviolet absorber, a pigment, a metal powder pigment, a rheology control agent, etc. may be added. The composition of the present invention can be used by directly applying it to a material to be coated such as metal such as steel plate and surface-treated steel plate or plastic. Further, as in the case of ordinary automobile coating, as a top coat of the coating material obtained by applying the primer / intermediate coating to the material to be coated as a vehicle, or by applying a normal solid coating or metallic coating. It can be used as a clear paint for protecting the top coat after the top coat is applied.

The composition of the present invention is an intermediate coating for automobiles,
It can be used for plastic paint, paint for pre-coated metal, etc. When the composition of the present invention is used as an automotive top coating, the coating method of the present invention is 15 to 3
Adjust the coating viscosity to about 0 seconds (Ford Cup # 4, 20 ° C) and use electrostatic coating or air spray to obtain a dry film thickness of 1
It should be about 0 to 60 μ. The baking and curing conditions are about 120 to 180 ° C. and about 10 to 30 minutes.

[0030]

EXAMPLES The present invention will be described in more detail with reference to examples. "Parts" in Examples and Comparative Examples are based on weight. (Yellowness Δb) The difference (increase) between the b value measured by a digital automatic colorimetric color difference meter (manufactured by Suga Test Instruments Co., Ltd.) and the b value of the coating film before baking, and evaluated as follows. did.

X: 1.5 or more Δ: 1 or more and less than 1.5
○: less than 1

[0032]

[Reference Example 1] (Production Method of Thermally Dissociable Block Polyisocyanate) A four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser was used as an isocyanurate-modified polyisocyanate compound using HMDI as a raw material (Asahi Chemical Industry Co., Ltd. )) "Duranate TPA")) (100 parts) in 35 parts of xylene, and then 50 parts of methyl ethyl ketoxime at 40-50 ° C.
Was added over 1 hour. It was confirmed by infrared spectrum that the absorption of the isocyanate group had disappeared, and a block polyisocyanate was obtained.

[0033]

[Reference Example 2] (Production of thermal dissociable block polyisocyanate) A four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser was used as a raw material for isocyanurate-modified polyisocyanate compound (Asahi Chemical Industry Co., Ltd. )) "Duranate THA")) (100 parts) is dissolved in 34 parts of xylene, and then 46 parts of methyl ethyl ketoxime is added at 40 to 50 ° C.
Was added over 1 hour. It was confirmed by infrared spectrum that the absorption of the isocyanate group had disappeared, and a block polyisocyanate was obtained.

[0034]

[Reference Example 3] 100 parts of isocyanurate-modified polyisocyanate compound (trade name "Duranate TPA" manufactured by Asahi Kasei Co., Ltd.) using HMDI as a raw material in a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. 35 parts of xylene, 48 parts of methyl ethyl ketoxime,
40 to 50 with a mixed solution of 1 part of N, N-dimethylhydrazine.
In the range of ° C, it was added over 1 hour. It was confirmed by infrared spectrum that the absorption of the isocyanate group had disappeared, and a block polyisocyanate was obtained.

[0035]

[Example 1] Acrylic polyol (Dainippon Ink Co., Ltd.)
Product name "Acridic A-801", solid content 50
%, Hydroxyl value 50 mg KOH / g) 100 parts, reference example-
Thermally dissociable block polyisocyanate 40 obtained in 1.
Parts (effective isocyanate / hydroxyl group molar ratio 1.0), dibutyltin dilaurate 0.41 part (vs. coating resin 0.5)
%), A compound containing the general formula (2) (trade name “HN-130” of Nippon Hydrazine Industries Co., Ltd.) 0.41 part (vs. coating resin 0.5% by weight), tin 2-ethylhexanoate 0 16 parts (0.2% by weight of the coating resin) were mixed, and ethyl acetate / toluene / butyl acetate / xylene / propylene glycol monomethyl ether acetate (weight ratio 30
The paint viscosity was adjusted to 20 seconds with a Ford cup # 4 with a thinner (30/20/15/5).
This was coated on a white tile with an air spray gun so that the dry coating film would have a thickness of 50 microns, set at room temperature for 30 minutes, and then baked at 180 ° C. for 30 minutes. The yellowing degree b value of the baked coating film was measured. The results are shown in Table 1.

[0036]

Examples 2 to 15 The same procedure as in Example 1 was carried out except that the effective isocyanate / hydroxyl group molar ratio was 1.0 and the coating compositions shown in Table 1 were used.

[0037]

[Example 16] Polyester polyol (trade name of Desmophen 670 manufactured by Sumitomo Bayer Urethane Co., Ltd., solid content 80%, OH group content 3.4) in place of acrylic polyol
%) Was used and the same curing agent as in Example 1 was added so that the effective isocyanate / hydroxyl group molar ratio was 1.0, and the same procedure as in Example 13 was performed. The results are shown in Table 1.

[0038]

Comparative Examples 1 to 4 The same procedure as in Example 1 was carried out except that the coating composition shown in Table 1 was used with the effective isocyanate concentration / hydroxyl group molar ratio being 1.0. The results are shown in Table 1.

[0039]

[Table 1]

[0040]

EFFECTS OF THE INVENTION The one-pack coating composition of the present invention has excellent weather resistance, flexibility and chemical resistance of the coating and does not yellow due to heat. It exhibits excellent performance as a paint for automobile bodies and plastics.

Claims (2)

[Claims] 1. A compound selected from at least two different groups selected from the group consisting of compounds containing a group represented by the general formula (1) or (2), a divalent tin compound group and a phosphite compound group. A one-pack coating composition containing the above compound, a heat dissociable block polyisocyanate and a polyhydroxy compound. [Chemical 1] [Chemical 2] 2. At least one compound selected from the group of compounds containing a group represented by the general formula (1), the group of divalent tin compounds and the group of phosphite compounds, a group represented by the general formula (2). A one-pack coating composition containing a heat-dissociable block polyisocyanate having: and a polyvalent hydroxy compound. [Chemical 3] [Chemical 4]