JPH07207228A - Cold-curing one-component coating composition - Google Patents

Abstract

PURPOSE:To obtain a cold-curing one-component coating compsn. which gives a coating film with excellent physical properties by compounding a specific polyol, a specific blocked polyisocyanate, and a specific cure accelerator. CONSTITUTION:This compsn. contains a polyol having a hydroxyl value of 10-300mgKOH/g (e.g. an acrylic polyol), an aliph. or alicyclic blocked polyisocyanate having a mean blocked-isocyanate functionality of 4.5-10, and a cure accelerator comprising at least one organotin compd. of formula l or II (wherein R1 and R3 are each 1-12C alkyl or aryl; R2 is H, 1--21C alkyl, alkenyl, aralkyl, alkoxyalkyl, or aryl; X and Y are each OCOR2, OH, halogen, 01/2, or S1/2; Z is O, S, or a dicarboxylic acid residue; and p is 0 or 1) and at least one organometallic compd. selected from the group consisting of a metal salt of an org. acid of formula III (wherein R4 is R2; N is Co, Ni, or Zn; and q is p) and a metal-diketone complex (of which the metal is Co, Ni, or Zn).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel urethane thermosetting coating composition.

[0002]

2. Description of the Related Art Conventionally, polyurethane resin paints have very excellent wear resistance, chemical resistance, and stain resistance.
Polyurethane resin coatings composed of aliphatic / alicyclic polyisocyanates have further excellent weather resistance, and their demand tends to increase. However, since polyurethane resin paints are generally two-part, it is extremely inconvenient to use them. That is, a usual urethane resin coating consists of two components, a polyol and a polyisocyanate, and it is necessary to store them separately and mix them at the time of coating. In addition, under the present circumstances, once mixed, the coating material gels in a short time and cannot be used. This makes automation of line painting for automobiles extremely difficult.

Further, since it is necessary to sufficiently wash the coating machine and the coating tank at the end of the work, the work efficiency is remarkably reduced. In order to improve the above-mentioned drawbacks, it has been conventionally proposed to use a block polyisocyanate in which all active isocyanate groups are blocked with a blocking agent. This block polyisocyanate does not react with polyols at room temperature, but at high temperatures it has the property of dissociating the blocking agent, regenerating the active isocyanate group and reacting with the polyol to cause a crosslinking reaction, so the above-mentioned drawbacks are temporarily improved. You can do it.

However, the above crosslinking reaction requires a high baking temperature. A high baking temperature is not only an increase in energy cost but also an accompanying increase in air pollution, which is a fatal drawback in coating a heat-sensitive object such as plastics. Therefore, it has excellent weather resistance in the spray coating, dipping coating, roll coating, electrodeposition coating, etc. performed on steel plates, metals, plastic molded products, etc. in automobiles, home appliances, office equipment, construction, etc. The advent of low one-part polyurethane resin coatings has been desired.

Several proposals have been made to reduce the crosslinking temperature. JP-B-44-18877, JP-A-53-138434, JP-A-56-8
In Japanese Patent No. 4714 and Japanese Patent Laid-Open No. 57-8217, a specific organotin compound is added as a catalyst. JP 62
In Japanese Patent Publication No. 199609, a lead compound and an inorganic zinc compound are added as catalysts. In JP-A-4-288378, specific tin and zinc compounds are used in combination.

[0006]

However, the cross-linking temperature of the above-mentioned paint using an aliphatic / alicyclic block polyisocyanate as a curing agent does not decrease so much, and for example, to a substrate having low heat resistance such as plastic. The application was limited and the use was limited. An object of the present invention is to provide a coating composition which lowers the crosslinking temperature of a coating composition using a specific aliphatic / alicyclic block polyisocyanate as a curing agent.

[0007]

The present inventors have succeeded in reducing the cross-linking temperature of a paint using the same by combining a specific block isocyanate, a specific polyol and a specific organometallic compound. Invented. Incidentally, JP-A-2
No. 199112 describes a catalyst system which is a component of the present invention, but nothing about the specific block polyisocyanates of the present invention.

That is, according to the present invention, the hydroxyl value of the resin component is 10 to 3.
00 mgKOH / g polyol, block isocyanate average functional group number per molecule of 4.5 to 10 aliphatic / alicyclic block polyisocyanate, and organic represented by the following formula (1) or (2) A curing accelerator comprising at least one tin compound and at least one metal compound selected from the organic acid metal salts represented by the following formula (3) and the diketone metal complex (metal is cobalt, nickel or zinc): The main purpose is a coating composition containing

[0009]

[Chemical 4]

[0010]

[Chemical 5]

[0011]

[Chemical 6]

The polyol used in the present invention is a compound having at least two hydroxyl groups in one molecule,
Examples of such compounds 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. Methylene glycols, polyether polyols obtained by further reacting alkylene oxide with a polyfunctional compound such as ethylenediamine and ethanolamines, and
So-called polymer polyols and the like obtained by polymerizing acrylamide and the like using these polyethers as a medium 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 the like, 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, an acrylic polyol resin obtained by copolymerizing a polymerizable UV-stable monomer exemplified in JP-A-1-261409 and JP-A-3-6273 can be used. . The polyol used in the present invention has a resin component hydroxyl value of 10 to 300 mgKOH /
It is g. When the hydroxyl value of the resin component is less than 10, the crosslinking density of the urethane due to the reaction with the isocyanate component is reduced, and the function of the urethane bond cannot be exhibited. When the hydroxyl value of the resin component exceeds 300, the crosslinking density is reversed. And the mechanical properties of the coating film deteriorate, and in some cases the hydroxyl group and the isocyanate group do not react completely.

Among these polyols, acrylic polyols and polyester polyols having a hydroxyl value of 20 to 200 and a number average molecular weight of 1,000 to 50,000 are particularly preferable. Aliphatic used in the present invention
The alicyclic block polyisocyanate has an average number of functional groups of block isocyanate of 4.5 to 10, preferably 5 to 8 per molecule.

The average number of block isocyanate functional groups of the block polyisocyanate is the number of block isocyanate functional groups statistically possessed by one molecule of the block polyisocyanate, and the number average molecular weight and the isocyanate of the polyisocyanate before blocking. It can be calculated from the nart concentration (%) by the following mathematical formula (1).

[0019]

[Equation 1]

For example, JP-A-61-2678,
JP-A-1-104664 discloses the number average molecular weight and the isocyanate concentration of polyisocyanate. From these values, the average number of isocyanate functional groups can be calculated by the formula (1).
The maximum value is 3.6 when calculated by. In addition, generally commercially available aliphatic / alicyclic polyisocyanates, for example, trade name “Desmodur N” of Bayer Co.,
Sumitomo Bayer Urethane "Sumijour N350
0 ”, the product name of Nippon Polyurethane Industry Co., Ltd.,“ Coronate H ”
"X", the product name of Asahi Kasei Corporation "Duranate 24A"
The average number of functional groups such as "duranate TPA" is about 3 to 4 in all cases. JP-A-2-132116 describes a specific polyisocyanate structure, and the number of isocyanate groups per molecule of polyisocyanate is 3 to 6 based on the structure. However, the polyisocyanate having the above value of 4 or more is an aromatic isocyanate. Japanese Unexamined Patent Publication (Kokai) No. 3-218344 describes a polyisocyanate having an average number of functional groups of 4 to 7, and one of the raw materials is isocyanate carboxylic acid chloride, which is industrially difficult to obtain and has a low viscosity. Therefore, the sagging property is not good. The block polyisocyanate (hereinafter referred to as a highly branched block polyisocyanate) constituting the present invention will be described in detail below.

In the highly branched block polyisocyanate, diisocyanate is one of the raw materials. The diisocyanate used in the present invention is preferably an aliphatic or alicyclic diisocyanate. The aliphatic diisocyanate preferably has 4 to 30 carbon atoms, and the alicyclic diisocyanate preferably has 8 to 30 carbon atoms, for example, 1,4-
Tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate,
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 1,3-bis (isocyanatomethyl)
-Cyclohexane, 4,4'-dicyclohexylmethane diisocyanate and the like can be mentioned. Above all,
From the viewpoint of weather resistance and industrial availability, 1,6-hexamethylene diisocyanate (hereinafter referred to as HMDI) and isophorone diisocyanate (hereinafter referred to as IPDI) are preferable, and they may be used alone or in combination. Is also good.

The hyper-branched block polyisocyanate obtained by using the diisocyanate can be obtained only by reacting the diisocyanate with a polyhydric alcohol having a valence of 3 or more, and more preferably, the diisocyanate and the polyhydric alcohol. Is obtained by reacting with, followed by cyclic trimerization of isocyanate, in other words, isocyanurate conversion.

The polyhydric alcohol in this case is preferably a trihydric or higher alcohol, and examples of the low molecular weight polyhydric alcohol include trimethylolpropane, glycerin,
Examples include 1,1,7-trimethylol heptane, 1,2,7-trimethylol heptane, and pentaerythritol. Examples of the high molecular weight polyhydric alcohol include aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, and epoxy resins.

Specific examples of the aliphatic hydrocarbon polyols include terminal 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 and resorcin type epoxy resins.

Among these polyols, preferred are the above-mentioned low molecular weight polyhydric alcohols and polyether polyols having 3 to 8 hydroxyl groups in one molecule, aliphatic hydrocarbon polyols and polyester polyols, and particularly preferred are It is a polyester polyol. These may be used alone or in combination of two or more. 50-200 for aliphatic / alicyclic diisocyanates and polyhydric alcohols
The reaction is carried out at a temperature of preferably 50 to 150 ° C. At this time, a solvent may be used, but it is preferable to use a solvent inert to isocyanate. This reaction can be performed after the isocyanurate-forming reaction, but is preferably performed before the isocyanurate-forming reaction.

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 selected from the range of 10 ppm to 1.0% with respect to the isocyanate compound.

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 are removed to obtain a highly branched polyisocyanate having an isocyanurate structure. The viscosity of the highly branched polyisocyanate containing no solvent at 25 ° C is 0.5 to 300.
Pas is preferred. If the viscosity is 300 Pas or more, the appearance of the coating film may be adversely affected, and if it is 0.5 Pas or less, it is difficult to obtain the range of the polyisocyanate average functional group number defined in the present invention.

Examples of the blocking agent used for obtaining the highly branched block polyisocyanate include phenol type, active methylene type, mercaptan type, acid amide type, acid imide type, imidazole type, urea type, oxime type, amine type, There are imide 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 highly branched block polyisocyanate can be obtained by reacting the above blocking agent with the highly branched polyisocyanate. The reaction between the isocyanate 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 highly branched block polyisocyanate thus obtained constitutes the main component of the paint together with the polyol. The equivalence ratio of the blocked isocyanate groups in the highly branched block polyisocyanate to the hydroxyl groups 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.

The curing accelerator used in the present invention will be described. One of them is an organotin compound represented by the above formula (1) or (2). In the formula, R1 and R3 are alkyl groups or aryl groups having 1 to 12 carbon atoms, and examples thereof include a methyl group, a butyl group, an octyl group, a lauryl group, and a phenyl group. Particularly, a butyl group and an octyl group are preferable. R2 is a hydrogen atom or an alkyl group having 1 to 21 carbon atoms, an alkenyl group, an aralkyl group, a cycloalkyl group, an alkoxyalkyl group or an aryl group,
-OCOR2 group has 2 to 2 carbon atoms having these R2 groups.
2 is a carboxylic acid residue, and as the carboxylic acid,
For example, formic acid, acetic acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, behenic acid, neopentanoic acid, neodecanoic acid, acrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, erucic acid, sorbic acid. , Linoleic acid, linolenic acid, phenylacetic acid, phenylbutyric acid, phenylpropionic acid, cyclopentanecarboxylic acid, acetoacetic acid, benzoic acid, methoxybenzoic acid, tert-butylbenzoic acid, hydroxybenzoic acid, etc., acetic acid, octyl acid , Lauric acid and benzoic acid are preferred.

The halogen of X and Y is, for example,
Examples include chlorine. As the divalent carboxylic acid residue of Z,
Examples thereof include residues of divalent aliphatic and aromatic carboxylic acids such as adipic acid, maleic acid and phthalic acid, and sulfur-containing divalent aliphatic carboxylic acids such as thiodipropionic acid. Particularly preferably, bis (dibutyltin monoacetate) oxide, bis (dibutyltin monooctylate) oxide,
Bis (dibutyltin monolaurate) oxide, bis (dibutyltin monobenzoate) oxide, bis (dioctyltin monoacetate) oxide, bis (dioctyltin monooctylate) oxide, bis (dioctyltin monolaurate) Oxide and bis (dioctyltin monobenzoate) oxide.

One example of the other curing accelerator used in combination with the organic tin compound is the organic acid metal salt represented by the above formula (3). In the formula (3), R4 is a hydrogen atom or a carbon number of 1 to 21.
Is an alkyl group, an alkenyl group, an aralkyl group, a cycloalkyl group, an alkoxyalkyl group or an aryl group, and the —OCOR2 group is a carboxylic acid group having 2 to 22 carbon atoms having these R4 groups. Examples of the acid include formic acid, acetic acid, caproic acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, neopentanoic acid, neoheptanoic acid,
Neodecanoic acid, acrylic acid, crotonic acid, isocrotonic acid, undecylenic acid, oleic acid, erucic acid, sorbic acid, linoleic acid, linolenic acid, phenylacetic acid, phenylbutyric acid, phenylpropionic acid, cyclopentanecarboxylic acid, acetoacetic acid, benzoic acid , Methoxybenzoic acid tert-butylbenzoic acid, hydroxybenzoic acid and the like are preferable, and acetic acid, octylic acid, lauric acid and benzoic acid are preferable, and bis (cobalt monoacetate salt) is particularly preferable.
Oxide, bis (cobalt monooctylate) oxide, bis (cobalt monolaurate) oxide,
Bis (cobalt benzoate) oxide, bis (nickel monoacetate) oxide, bis nickel monooctylate) oxide, bis (nickel monolaurate)
Oxide, bis (nickel monobenzoate) oxide, bis (zinc monoacetate) oxide, bis (zinc monooctylate) oxide, bis (zinc monolaurate) oxide, bis (zinc monobenzoate) oxide Can be mentioned.

The other curing accelerator used in combination may be a diketone metal complex described below. The diketone metal complex used in the present invention forms a complex compound of a diketone having two> C = O groups in the molecule with cobalt, nickel or zinc. The diketone is represented by the following formula (4). The one shown in is used.

[0039]

[Chemical 7]

Examples of the alkyl group represented by R5, R6 and R7 in the formula (4) include a methyl group, an ethyl group,
Propyl group, isopropyl group, butyl group, isobutyl group, secondary butyl group, acyl group, neopentyl group, isoamyl group, hexyl group, isohexyl group, heptyl group, octyl group, isooctyl group, 2-ethylhexyl group, decyl group, isodecyl group , Lauryl group, tridecyl group, stearyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, cyclododecyl group, 4-methylcyclohexyl group and the like. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the arylalkyl group include a benzyl group, a β-phenylethyl group, a γ-phenylpropyl group and the like. As the alkylaryl group, for example,
Tolyl group, xylyl group, ethylphenyl group, butylphenyl group, tert-butylphenyl group, octylphenyl group, isooctylphenyl group, tert-aryoctylphenyl group, nonylphenyl group, dinonylphenyl group,
2,4-ditertiary butyl phenyl group etc. are mentioned.

Examples of the cycloalkyl group represented by R6 and R7 include a cyclohexyl group and a cyclooctyl group, and examples of the alkoxyaryl group include a methoxyphenyl group, a propoxyphenyl group and a butoxyphenyl group. Β represented by the preferred formula (4)
-As diketone, cobalt stearoyl benzoyl methane, cobalt dibenzoyl methane, cobalt diacetyl methane, nickel stearoyl benzoyl methane, nickel diacetyl methane, nickel butanoyl
Acetyl methane, zinc stearoyl benzoyl methane, zinc dibenzoyl methane, zinc diacetyl methane,
Zinc butanoyl acetyl methane.

In the present invention, cobalt selected from the organic acid metal salts represented by the formula (3) and the diketone metal complexes, which is used in combination with the organic compound represented by the formula (1) or (2), The combination ratio of nickel or zinc with the metal compound is 9: 1 to 1: 9 by weight ratio, preferably 1:
It is 1-2: 8. If it is out of this range, it is difficult to exert an excellent catalytic effect.

The amount of the curing accelerator added is not particularly limited, but is usually 0.01 to 10% by weight, preferably 0.5 to 5% by weight, based on the resin solid content. Further, in the composition of the present invention, a suitable solvent is optionally used when mixing the components, for example, hydrocarbons such as benzene, toluene, xylene, cyclohexane, mineral spirits, naphtha, acetone, methyl ethyl ketone, methyl isobutyl ketone. And the like, and esters such as ethyl acetate, ethyl acetate-n-butyl acetate, and cellosolve acetate can be appropriately selected and used according to the purpose and application.
These solvents may be used alone or in combination of two or more.

If necessary, an antioxidant, an ultraviolet absorber, a pigment and the like may be added.

[0045]

The present invention will be described in more detail based on the following examples. All percentages are shown by weight. The evaluation was performed according to the following. (Measurement of Number Average Molecular Weight) The number average molecular weight is a polystyrene standard number average molecular weight measured by gel permeation chromatography using the following device. Device: Tosoh Corp. HLC-802A Column: Tosoh Corp. G1000HXL × 1 bottle G2000HXL〃 G3000HXL〃 Carrier: Tetrahydrofuran Detection method: Differential refractometer (viscosity measurement) At 25 ° C using an Emila type rotational viscometer It was measured. (Gel Fraction) The value of the undissolved part weight of the cured coating film when immersed in acetone at 20 ° C. for 24 hours was calculated. The value was x when less than 80% and Δ when 80% or more and less than 90%. 9
0% or more is represented by O. (Coating film haze) A coating film having a film thickness of 50 μm applied to a transparent glass plate having a thickness of 1 mm was measured by a direct reading haze computer HGM-2DP of Suga Test Instruments Co., Ltd. 0.5
Less than is represented by O, and 0.5 or more is represented by X. (Coating film gloss) A coating film having a film thickness of 50 μm coated on a white tile was measured at 60 ° with a digital automatic colorimeter of Suga Test Instruments Co., Ltd. A value of 95 or more is represented by O, and a value of less than 95 is represented by X.

[0046]

[Reference Example 1] (Production of hyperbranched polyisocyanate) A 4-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube, and a dropping funnel was placed in a nitrogen atmosphere,
HMDI 600 parts 30 parts of polyester polyol "Plaxel 303" (trade name of Daicel Chemical Industries), which is a trihydric alcohol, was charged and the temperature inside the reactor was 90 ° C under stirring.
Hold for time to carry out urethane reaction. Thereafter, the temperature in the reactor was maintained at 60 ° C., the isocyanurate-forming catalyst tetramethylammonium capryate was added, and when the yield reached 54%, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HMDI was removed using a thin film evaporator. The obtained highly branched polyisocyanate has a viscosity at 25 ° C. of 7,000 mPas and an isocyanate concentration of 1
The number average molecular weight was 9.2% and 1,100.

[0047]

[Reference Examples 2 to 6] (Production of hyperbranched polyisocyanate) Using the same apparatus as in Reference Example 1, production was carried out under the reaction conditions shown in Table 1. Table 1 also shows the physical properties of the obtained highly branched polyisocyanate.

[0048]

Comparative Reference Example 1 Using the same apparatus as in Reference Example 1, the reaction conditions shown in Table 1 were used. The physical properties of the obtained product are also shown in Table 1.
Shown in. If the polyhydric alcohol was not used, the hyperbranched polyisocyanate of the present invention could not be obtained.

[0049]

[Production Example 1] (Production of highly branched block polyisocyanate) A 4-necked flask equipped with a stirrer, a thermometer, a reflux cooling tube, a nitrogen blowing tube, and a dropping funnel is filled with a nitrogen atmosphere,
Hyperbranched polyisocyanate 100 obtained in Reference Example 1
And 35 parts of xylene were charged, methyl ethyl ketoxime was added dropwise so that the reaction temperature did not exceed 50 ° C. until the characteristic absorption of the isocyanate in the infrared spectrum disappeared, and a highly branched block polyisocyanate solution with a solid content of 80% was added. Obtained. The average number of functional groups calculated from the formula (1) was 5.1.

[0050]

[Production Examples 2 to 6] (Production of highly branched block polyisocyanate) A highly branched block having a solid content of 80% is prepared in the same manner as in Production Example 1 except that the highly branched polyisocyanate obtained in Reference Examples 2 to 6 is used. A polyisocyanate was obtained. The average numbers of these functional groups are 5.1, 5.2, 6.6 and 7.
6 and 7.1.

[0051]

[Comparative Production Example 1] (Production of block isocyanate) HMDI-based polyisocyanate "Duranate TPA-"
100 "(trade name of Asahi Chemical Industry Co., Ltd., average number of functional groups of isocyanate is 3.2, viscosity of 1400 mPas / 25 ° C.) was used in the same manner as in Production Example 1 to obtain a block isocyanate solution having a solid content of 80%. .

[0052]

[Comparative Production Example 2] (Production of block isocyanate) HMDI-based polyisocyanate "Sumijour N350"
0 "(trade name of Sumitomo Bayer Urethane, average number of functional groups of isocyanate 3.3, viscosity 2500 mPas / 25
℃) was used in the same manner as in Production Example 1 except that the solid content was 80
% Block isocyanate solution was obtained.

[0053]

[Comparative Production Example 3] (Production of block isocyanate) HMDI polyisocyanate "Coronate HX" (trade name of Nippon Polyurethane, average number of functional groups of isocyanate 3.4, viscosity 2000 mPas / 25 ° C) was used except that The same procedure as in Production Example 1 was carried out to obtain a block isocyanate solution having a solid content of 80%.

[0054]

[Comparative Production Example 4] (Production of block isocyanate) A block isocyanate solution having a solid content of 80% was obtained in the same manner as in Production Example 1 except that the polyisocyanate obtained in Comparative Reference Example 1 was used.

[0055]

Examples 1 to 8 (Coating composition using highly branched block polyisocyanate and organometallic compound) The highly branched block polyisocyanate and acrylic polyol obtained in Production Examples 1 to 6 (trade name of Dainippon Ink and Co., Ltd.) Acrydike A-801) was blended so that the isocyanate / hydroxyl group ratio (equivalent) was 1.0, and an organometallic compound was further added as shown in Table 1 to which ethyl acetate / toluene / butyl acetate as thinner was added. / Xylene / propylene glycol monomethyl ether acetate (weight ratio = 30/30/20/15/5) was added, and the temperature was adjusted to 20 seconds / 20 ° C. with Ford cup # 4. The resulting coating solution was adjusted to have a dry film thickness of 50 μm with an air spray gun, and baked in an oven maintained at 100 and 120 ° C. for 30 minutes. Table 2 shows the obtained coating film physical property measurement results.

[0056]

Comparative Examples 1 to 5 (Coating Composition Using Block Isocyanate) The same procedure as in Example 1 was carried out except that the block isocyanates obtained in Comparative Production Examples 1 to 4 were used. The formulations and results are shown in Table 3.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

EFFECTS OF THE INVENTION According to the present invention, not only is it possible to cure at a low temperature as compared with a conventional one-component polyurethane paint mainly composed of a polyol and a block isocyanate,
Excellent coating film properties can be obtained.

Claims (1)

[Claims] 1. A resin component having a hydroxyl value of 10 to 300 mg KOH /
g of a polyol, an aliphatic / alicyclic block polyisocyanate having an average number of functional groups of block isocyanate of 4.5 to 10 per molecule, and an organotin compound represented by the following formula (1) or (2) At least one,
Organic acid metal salt and diketone metal complex represented by the following formula (3) (metal is cobalt, nickel or zinc)
A coating composition containing a curing accelerator comprising at least one metal compound selected from the group consisting of: [Chemical 1] [Chemical 2] [Chemical 3]