JPH04334573A - Coat formation - Google Patents

Abstract

PURPOSE:To improve finishing and recoating properties by using each specific paint composition as one for forming a color base coat and a clear top coat applied to an external automotive plate as a finish coat. CONSTITUTION:Polymer resin containing a hydroxyl group, amino acid, polyorganocyclohexane with number average molecular weight of 1000 or higher containing average two or more silanol groups and/or alkoxy silane groups and average one or more epoxy groups in a single molecule, metal flake powder and mica powder are used as a paint composition which forms a color base coat in a finish coating technique based on a two coat/one baking system. In addition, a resin containing a silanol group and/or a hydrolytic group bonded to a silicon atom, a hydroxyl group and an epoxy group, curable catalyst and an organic solvent are used as a paint composition which forms a clear top coat.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new method for forming a coating film, and more particularly, to a method for forming a coating film that has an excellent finished appearance.

0002

BACKGROUND OF THE INVENTION Conventionally, there has been a demand for improvements in finished appearance, coating performance, etc. in top coats, particularly top coats for automobile exterior panels. In addition, there is a strong demand for the development of low-temperature curing coatings for the purpose of reducing energy costs and making it possible to apply the same paint to the exterior of automobiles where steel plate base materials and plastic base materials are integrated. be.

[0003] The currently mainstream paints for automobiles are thermosetting acrylic resin/melamine resin paints,
Thermosetting polyester resin/melamine resin-based paints, etc., are close to their limits in terms of high level of smoothness, and there is still room for improvement in various coating film performances. Further, there is a problem that the low temperature curing property is not sufficient. Furthermore, there are still problems such as peeling of the paint film and environmental pollution due to condensates (such as formalin) generated during baking.

The present applicant proposed a coating composition for automobiles in Japanese Patent Laid-Open No. 2-160879 as a coating material with excellent low-temperature curability. The paint is a silicone paint composition made by blending a metal chelate compound into a copolymer containing a polysiloxane macromonomer containing a silanol group and/or an alkoxysilane group and a vinyl monomer containing an oxirane group as monomer components. If this product is applied to both a metallic base coat (paint containing aluminum flake pigment) and a clear top coat, and a two-coat, one-bake finish is applied, the metallic base coat will be affected by the clear top coat. The drawback is that the orientation of the aluminum flake pigment changes, making it impossible to obtain a coating film with aluminum luster (sparkling, white). Additionally, when a thermosetting polyester resin/melamine resin based metallic base coat is used, the clear top coat begins to harden before the metallic base coat begins to harden, resulting in defects such as wrinkles and wrinkles in the paint film. It had the disadvantage of causing

[0005] Furthermore, when a defect occurs in the finish coating, the same type of metallic base coat and clear top coat are usually recoated to repair the defective part.
Those using the above-mentioned silicone-based coating compositions also had the problem that adhesion between the coating films (top clear coat and metallic base coat to be recoated) was insufficient.

[0006]

[Means for Solving the Problems] As a result of extensive research in order to eliminate the above-mentioned drawbacks, the present inventors have found that by forming a combination of a specific colored base coat and a specific clear top coat, the finish quality is improved. The present inventors have discovered that it is possible to provide a coating film with excellent recoatability, and have completed the present invention.

That is, the present invention provides a top coating method in which a colored base coat and a clear top coat are sequentially formed on a material and finished by a two-coat, one-bake method, in which (1) a hydroxyl group-containing polyester resin is used as a coating composition for forming the colored base coat. (2) Amino resin (3) Polyorganosiloxane with a number average molecular weight of 1000 or more and having an average of two or more silanol groups and/or alkoxysilane groups and an average of one or more epoxy groups in one molecule (4) Metal flake powder and/or mica powder, and (5) a coating composition that forms a clear top coat using a coating composition containing an organic solvent as an essential component. Resin having decomposable group, hydroxyl group and epoxy group (2
The present invention relates to a coating film forming method characterized by using a coating composition containing as essential components a) curing catalyst and (3) an organic solvent.

Next, the method of the present invention will be specifically explained.

◎ Colored base coat The colored base coat contains (1) a hydroxyl group-containing polyester resin, (2) an amino resin, (3) an average of two or more silanol groups and/or alkoxysilane groups in one molecule, and an average of one or more silanol groups and/or alkoxysilane groups.
(4) metal flake powder and/or mica powder (hereinafter simply referred to as "metal ) and (5) a base coat coating composition containing an organic solvent as an essential component.

The hydroxyl group-containing polyester resin has a hydroxyl group in its molecule and preferably has a hydroxyl value of about 20 to 20.
0, more preferably in the range of about 50 to 150. When the hydroxyl value is less than 20, the curing speed of the base coat film becomes slower than the curing speed of the top coat film, and the top coat film cures before the base coat film hardens, resulting in wrinkles etc. on the cured top coat film. Defects occur, and the finished appearance of the paint film deteriorates. Also,
Since the curing is not sufficient, the performance of the coating film (water resistance, impact resistance, etc.) may deteriorate, which is not preferable. On the other hand, if the hydroxyl value is greater than about 200, a large amount of unreacted hydroxyl groups will remain in the coating film, resulting in a decrease in coating film performance (water resistance, weather resistance, etc.), which is not preferable.

[0011] Furthermore, as the hydroxyl group-containing polyester resin, those containing carboxyl groups in the molecule can be used. In particular, carboxyl groups improve the rate of reactions such as reactions between hydroxyl groups and amino groups, reactions between hydroxyl groups and silanol groups and/or alkoxysilane groups, and reactions between silanol groups and/or alkoxysilane groups, and improve coating film finish. It has the effect of The carboxyl group has a resin acid value of about 0 to 50, preferably about 5 to 20.

The hydroxyl group-containing polyester resin is an oil-free alkyd resin prepared by reacting a polybasic acid, a polyhydric alcohol, and if necessary an aromatic monobasic acid, or a polybasic acid, a polyhydric alcohol, and a polybasic acid, if necessary. Examples include alkyd resins produced by reacting an aliphatic monobasic acid in addition to an aromatic monobasic acid.

The polybasic acid, polyhydric alcohol, aromatic or aliphatic monobasic acid used in the production of the above (oil-free) alkyd resin will be described below.

Examples of polybasic acids include phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydroterephthalic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, het acid, trimellitic acid, and hexahydrophthalic acid. hydrotrimellitic acid,
Pyromellitic acid, cyclohexanetetracarboxylic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic acid, endomethylenehexahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, adipine acid,
Azelaic acid, sebacic acid, decane dicarboxylic acid, suberic acid, pimelic acid, dimer acid (tall oil fatty acid dimer), tetrachlorophthalic acid, naphthalene dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4
'-dicarboxybiphenyl, acid anhydrides and dialkyl esters thereof, particularly dimethyl esters, and the like.

Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, and 1,5-pentanediol. , 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, 3
-Methyl-pentane-1,5-diol, 3-methyl-
4,5-pentanediol, 2,2,4-trimethyl-
1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, dipropylene glycol, Ethylene glycol, neopentyl glycol, hydroxypivalic acid neopentyl glycol ester, polyalkylene oxide, bishydroxyethyl terephthalate, alkylene oxide adduct of (hydrogenated) bisphenol A, glycerin, trimethylolpropane, trimethylolethane, diglycerin, penta Erythritol, dipentaerythritol,
Examples include sorbitol. Also Cardura E10 [
Shell Chemical Co., Ltd.], α-olefin epoxide, butylene oxide, and other monoepoxy compounds can also be used as a type of glycol.

Compounds having both carboxylic acid and hydroxyl groups in the molecule can also be used. Such compounds include, for example, dimethylolpropionic acid, pivalic acid, 12
-Hydroxystearic acid, ricinoleic acid, etc. In addition, lactones such as ε-caprolactone and γ-valerolactone are also cyclic ester compounds and therefore belong to the above-mentioned category of compounds.

Examples of aromatic monobasic acids include benzoic acid and p-tert-butylbenzoic acid.

Examples of aliphatic monobasic acids include caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isononanoic acid, and coconut oil (fatty acid).

The above-mentioned (oil-free) alkyd resin can be produced by a conventionally known method, for example, using a mixture of the above-mentioned polybasic acid, polyhydric alcohol and, if necessary, a monobasic acid, using an esterification catalyst (for example, dibutyltin dilaurate, etc.). This can be carried out by carrying out an esterification reaction or transesterification reaction in the presence of. The blending ratio of the polybasic acid and polyhydric alcohol is about 0.7 to 0.99 mol, preferably about 0.8 to 0.9 mol, of the polybasic acid component per 1 mol of the polyhydric alcohol component.
A range of 8 moles is desirable. The esterification catalyst is about 0.1 to 1.0 parts by weight, preferably about 0.2 to 1.0 parts by weight, based on 100 parts by weight of the total amount of polyhydric alcohol and polybasic acid components.
It is desirable that the amount is 0.5 parts by weight. The reaction conditions are usually about 160-280°C, preferably about 180-280°C.
About 5 to 12 hours, preferably about 6 to 12 hours at a reaction temperature of 60 °C
A reaction time range of 8 hours is good.

In addition to the above-mentioned (oil-free) alkyd resins, for example, vinyl-modified alkyd resins can be used. Examples of the vinyl-modified alkyd resin include a reaction product of a hydroxyl group-containing (oil-free) alkyd resin and a carboxyl group- or isocyanate group-containing vinyl resin, a reaction product of a hydroxyl group- and carboxyl group-containing (oil-free) alkyd resin, and an epoxy group-containing vinyl resin. Reactant: an (oil-free) alkyd resin having a radically polymerizable unsaturated group (e.g., an alkyd resin containing a drying oil as an essential component, an (oil-free) alkyd resin containing a hydroxyl group and a carboxyl group, reacted with glycidyl (meth)acrylate) Those obtained by radical polymerization of vinyl monomers (for example, the polymerizable unsaturated monomer (b) described below) in the presence of alkyd resins, etc.);
Oil-free) alkyd resin, vinyl-modified alkyd resin, etc. are used as a dispersion stabilizer, and in the presence of the dispersion stabilizer, a vinyl monomer (for example, the polymerizable unsaturated monomer (b) described below) is added to the monomer. An organic solvent in which the monomer and the dispersion stabilizer are dissolved, but the polymer particles obtained from the monomer are not dissolved therein, and the polymerization reaction is carried out can be used.

The molecular weight of the hydroxyl group-containing polyester resin is a number average molecular weight, and can be in the range of, for example, about 500 to 10,000 for (oil-free) alkyd resins, and about 2,000 to 80,000 for vinyl-modified alkyd resins. If the molecular weight is below the above range, the melt viscosity of the base coat will decrease during baking and the orientation of the metal flakes will change, making it difficult to obtain a coating with a metallic feel.On the other hand, if the molecular weight is above the above range, painting workability will generally decrease. It is not desirable because

Amino resins are used as crosslinking agents, and include methylolated amino resins obtained by reacting amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide with aldehydes. . Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Furthermore, etherification of this methylolated amino resin with a suitable alcohol can also be used. Examples of alcohols used for etherification include methyl alcohol,
Examples include ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol, and the like. As the amino resin, melamine with a high degree of etherification, that is, melamine with an average of 3 or more methyl ethers per triazine nucleus, or melamine resin in which a part of the methoxy group is replaced with an alcohol having 2 or more carbon atoms is used. can. Among them, low molecular weight melamine having an average degree of condensation of about 2 or less and a proportion of mononuclear bodies of about 50% by weight or more is preferable from the viewpoint of high solidity. Preferably, a curing catalyst is added.

[0023] Polyorganosiloxane is used as a crosslinking agent for the hydroxyl group-containing polyester resin together with the amino resin, and as a self-crosslinking resin, and has an average of 2 or more, preferably 2 to 10, in one molecule. silanol groups and/or alkoxysilane groups and an average of 1
It is a polyorganosiloxane having 1 to 30 epoxy groups, preferably 1 to 30 epoxy groups.

This polyorganosiloxane preferably has a ladder structure, and is obtained by hydrolytic co-condensation of a silane represented by the following general formula (I) and an epoxy group-containing silane represented by the general formula (II). be able to.

R1xSi(OR2)4-x...(I
) (In the above formula, R1 and R2 may be the same or different and represent a hydrocarbon group having 1 to 13 carbon atoms, and x is 1 or 2
Or represents 3. )

[0026]

[Chemical formula 1]

(In the above formula, R3 and R4 may be the same or different and represent a hydrocarbon group having 1 to 13 carbon atoms,
y represents 1, 2 or 3, G represents the following formula (III) or (
IV) shows a group represented by IV). )

[0028]

[Case 2]

[0029]

[Chemical formula 3]

(In the above formulas (III) and (IV), R5 represents a hydrocarbon group having 1 to 13 carbon atoms, and R6 is the same or different and represents a hydrogen atom or a methyl group.) (I Although the blending ratio of the silane of formula ) and the silane of formula (II) is not particularly limited, it is usually
Silane of formula I: silane of formula (II) is 95:5-10
:90 (weight ratio), and in the silane to be blended, the sum of the silane in which x in formula (I) is 1 and the silane in which y in formula (II) is 1 is 30% by weight or more. It is preferably 80% by weight or more, and more preferably 80% by weight or more.

Representative examples of the silane of formula (I) include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, ethyltrimethoxysilane, Examples include dimethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diisobutyldimethoxysilane, diisobutyldipropoxysilane, and trimethylmethoxysilane.

Representative examples of the silane of formula (II) include γ
-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,
Examples include 4-epoxycyclohexyl)ethyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane.

In the hydrolytic cocondensation reaction of the silanes of formulas (I) and (II), these silane compounds are mixed with a water-soluble solvent (for example, an alcohol solvent, a cellosolve solvent, etc.) as necessary, and then treated with hydrochloric acid. , in the presence of a catalyst such as a mineral acid such as sulfuric acid or phosphoric acid or an organic acid such as formic acid or acetic acid, and water, preferably at a pH of 6 or below, at a temperature of about 20°C to 100°C.
This is carried out by allowing the hydrolysis and condensation reactions to proceed while stirring for about minutes to 20 hours.

The molecular weight of the polyorganosiloxane can be adjusted as appropriate by adjusting the amount of water used, the type and amount of catalyst, reaction temperature, reaction time, etc.

In the polyorganosiloxane resin, if the number of silanol groups and/or alkoxysilane groups or the number of epoxy groups is below the above range, the curing speed of the base coat film will be slower than the curing speed of the top coat film. Since the top coat film begins to harden before the base coat film is cured, defects such as wrinkles occur in the cured top coat film and the finished appearance of the paint film deteriorates.

[0036] In addition, when the number average molecular weight of polyorganosiloxane resin is smaller than 1000, the melt viscosity of the base coat decreases during baking, and the orientation of metal flakes changes, making it impossible to obtain a coating film with a metallic feel. There is.

[0037] Metal flakes give a metallic feel to the coating film, and examples of the metal flakes include aluminum flakes, nickel flakes, copper flakes, brass flakes, and chrome flakes, and examples of mica powder include Examples include pearl mica and colored pearl mica.

Examples of organic solvents include aromatic hydrocarbons such as xylene and toluene; esters such as ethyl acetate, propyl acetate, and butyl acetate; ketones such as acetone and methyl ethyl ketone; ethylene glycol, cellosolve, butyl cellosolve, and cellosolve acetate. Examples include ether-based solvents such as . These organic solvents can be used alone or in combination of two or more. Further, from the viewpoint of finishability, those having a boiling point of about 150° C. or lower are preferable, but are not limited thereto.

In the base coat coating composition, the blending ratio of the hydroxyl group-containing resin, amino resin, and polyorganosiloxane as a binder is based on the total amount of the three components (resin solid content) of 100 parts by weight, and 5 parts of the hydroxyl group-containing resin resin.
-90 parts by weight, preferably 30-60 parts by weight, 5-50 parts by weight of amino resin, preferably 10-40 parts by weight, 1-40 parts by weight of polyorganosiloxane, preferably 5-3 parts by weight
The amount may be 0 parts by weight, more preferably 5 to 20 parts by weight.

If the amount of the hydroxyl group-containing resin is less than 5 parts by weight, the adhesion to the substrate will decrease, while if it exceeds 90 parts by weight, the finished appearance of the coating film and the coating performance (water resistance, processability, etc.) will deteriorate. decreases. If the blending ratio of the amino resin is less than 5 parts by weight, the crosslinking density of the hydroxyl group-containing resin will be low, resulting in poor water resistance and
Impact resistance is significantly impaired, and if more than 50 parts by weight is added, problems such as decreased mechanical properties and adhesion to the substrate will occur. Furthermore, if the blending ratio of polyorganosiloxane is less than 1 part by weight, the effect of accelerating the curing speed of the base coat coating film is small and the finished appearance of the coating film cannot be improved, while on the other hand, if it exceeds 40 parts by weight, it is difficult to accelerate the curing speed of the base coat film. Adhesion deteriorates.

In addition to the above-mentioned components, the base coat coating composition may optionally contain organic pigments, inorganic pigments, pigment dispersants, fine polymer particles, ultraviolet absorbers, coating surface conditioners, curing catalysts, cellulose acetate ( and derivatives thereof),
Other paint additives and the like may also be added.

[0042] Pigments that may be incorporated into the paint include:
For example, organic pigments (e.g., quinacridone-based pigments such as quinacridone red, azo-based pigments such as pigment red, phthalocyanine-based materials such as phthalocyanine blue, phthalocyanine green, etc.), inorganic pigments (e.g., titanium oxide, barium sulfate,
(calcium carbonate, baryta, clay, silica, etc.), carbon pigments (carbon black), etc. .

◎Clear Top Coat The clear top coat consists of (1) a base resin containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom, a hydroxyl group, and an epoxy group (hereinafter referred to as "base resin for top coat"); ), (2) a curing catalyst, and (3) an organic solvent as essential components.

The hydrolyzable group possessed by the base resin for top coat is a residue that is hydrolyzed in the presence of water to produce a silanol group, such as a C1-5 alkoxy group;
Aryloxy groups such as phenoxy group, tolyloxy group, paramethoxyphenoxy group, paranitrophenoxy group, benzyloxy group; acetoxy group, propionyloxy group, butanoyloxy group, benzoyloxy group, phenylacetoxy group, formyloxy group, etc. Acyloxy group;
-N(R7)2, -ON(R7)2, -ON=C(R7
)2, -NR8COR7 (in the formula, each R7 is the same or different and represents a C1-8 alkyl group, an aryl group, or an aralkyl group, and R8 represents H or a C1-8 alkyl group) and so on.

As the base resin for the top coat, for example, (1) hydroxyl group-containing resin (A), epoxy group-containing resin (
B), a resin mixture containing three components: a resin (C) containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom (hereinafter abbreviated as "resin (1)"), (2)
Epoxy group-containing resin (B), resin containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom (C
), in which either one or both of resin (B) and resin (C) contains a hydroxyl group (hereinafter abbreviated as "resin (2)"), (
3) A resin containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom, a hydroxyl group, and an epoxy group (hereinafter abbreviated as "resin (3)"), and the like.

Resin (1); As the hydroxyl group-containing resin (A), those having an average of two or more hydroxyl groups in one molecule and preferably having a number average molecular weight of 1,000 to 200,000, preferably 3,000 to 80,000 are used. can. If the number of hydroxyl groups is less than 2 on average, the curability (gel fraction) will be poor, which is not preferable. The number of hydroxyl groups is preferably 400 or less on average from the viewpoint of finish quality, water resistance, etc. If the number average molecular weight is less than 1,000, mechanical properties, finishing properties, water resistance, etc. will be inferior, while if it exceeds 200,000, compatibility with other components will decrease, resulting in uneven curing and poor finish. I don't like it because it becomes a thing.

As the hydroxyl group-containing resin (A), conventionally known resins can be used, but it is particularly preferable to use a vinyl polymer from the viewpoint of weather resistance, finishing properties, etc.

The vinyl polymer can be obtained by radical polymerization of, for example, the following hydroxyl group-containing polymerizable unsaturated monomer (a) and, if necessary, other polymerizable unsaturated monomers (b). Co)polymers can be used.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (a) include (a-1) to (a-5).

(a-1) Hydroxy alkyl vinyl ether: hydroxybutyl vinyl ether, etc. (a-2)
Allyl alcohol, methallyl alcohol, etc. (a-3) Hydroxyalkyl esters of (meth)acrylic acid: hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc. (a-4) (Poly)alkylene glycol monoacrylate: ethylene glycol monoacrylate, polyethylene glycol monoacrylate, etc. (a-5) (a-1) to (a-4) and lactones (e.g. ε-caprolactone, γ-valerolactone) additions etc.

In addition, other polymerizable unsaturated monomers (b)
For example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate,
C1-24 alkyl or cycloalkyl esters of (meth)acrylic acid such as hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate; styrene, vinyltoluene, etc. vinyl aromatic compounds such as; perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate, perfluoroisononylethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate; (meth)acrylonitrile; olefins; fluoroolefins; vinyl esters; cyclohexyl or alkyl vinyl ethers; aryl ethers and the like.

The epoxy group-containing resin (B) has an average of 2 to 300 epoxy groups in one molecule, preferably a number average molecular weight of 120 to 200,000, more preferably 2
40 to 80,000. If the number of epoxy groups is less than 2 on average, the curability, finishing properties, and impact resistance will be poor, which is not preferable. It is difficult to obtain a compound with a number average molecular weight of less than 120, on the other hand, when the number average molecular weight exceeds 200,000, the compatibility with other components is poor,
As a result, the weather resistance, finishing properties, etc. of the resulting coating film are deteriorated, which is undesirable.

As the epoxy group-containing resin (B), an alicyclic polyepoxide crosslinking agent (for example,

[0054]

[C4]

[0055]

[C5]

[0056]

[C6]

[0057]

[C7]

[0058]

[Chemical formula 8]

etc.), oxirane group-containing polymerizable unsaturated monomers (c) (for example, alicyclic vinyl monomers of general formulas (4) to (18) described in JP-A-2-160879, etc.) A homopolymer or a copolymer with the other polymerizable unsaturated monomer (b) mentioned above can be suitably used.

Examples of the resin (C) containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom include γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, and γ-(meth)acryloxypropyltrimethoxysilane. Ethoxysilane, γ-(meth)acryloxypropyltrisilanol, γ-(meth)acryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-styrylethyltrimethoxysilane, allyltriethoxysilane, etc. Silane compounds such as (d
-1), a reaction product (d-2) of the silane compound (d-1) and a trialkoxy or trihydroxysilane compound (e.g. methyltrimethoxysilane, phenyltrimethoxysilane, methyltrisilanol) (e.g. JP −
Homopolymers of the polysiloxane macromonomers described in Japanese Patent No. 160879 or copolymers with other polymerizable unsaturated monomers (b) can be preferably used.

The blending ratio of the resins (A), (B) and (C) is based on the total amount of these three components.
) 5 to 95% by weight, preferably 20 to 80% by weight, resin (B) 95 to 5% by weight, preferably 80 to 20% by weight,
The resin (C) is preferably in the range of 0.1 to 80% by weight, preferably 1 to 20% by weight, from the viewpoint of curability and coating finish properties.

Resin (2): Epoxy group-containing resin (B),
As the resin (C) containing a silanol group and/or a hydrolyzable group directly bonded to a silicon atom, the same resins as mentioned above can be used.

[0063] Furthermore, in resin (2), resin (B)
Either or both of the resin (C) and the resin (C) have a hydroxyl group. In order to introduce a hydroxyl group into the resin (B) and resin (C), for example, the hydroxyl group-containing polymerizable unsaturated monomer (a) may be used as an essential monomer component. In this case, it is appropriate that the number of hydroxyl groups in one molecule is on average 1 or more, preferably on average 400 or less. The number average molecular weight of each resin is 10
00-200000, preferably 3000-80000
It is desirable to do so.

[0064] The blending ratio of the resins (B) and (C) is based on the total amount of these two components.
5 to 95% by weight, preferably 20 to 80% by weight, resin (
C) A range of 95 to 5% by weight, preferably 80 to 20% by weight is preferred from the viewpoint of curability and coating finish properties.

The hydroxyl group-containing resin (A) may be blended with the resin (2) if necessary.

Resin (3): The resin (3) has an average of 1 or more, preferably an average of 2 to 40 silanol groups and/or hydrolyzable groups directly bonded to silicon atoms in one molecule.
It is preferable to have an average of 1 or more epoxy groups, preferably 2 to 40 epoxy groups in a molecule, and an average of 2 to 200 hydroxyl groups in a molecule from the viewpoint of curability and coating finish.

Examples of the resin (3) include the hydroxyl group-containing polymerizable unsaturated monomer (a), the oxirane group-containing polymerizable unsaturated monomer (c), and the silane compound (d-1).
And/or a copolymer of the reactant (d-2) and, if necessary, another polymerizable unsaturated monomer (b) can be suitably used.

The blending ratio of the monomers (a) to (d-2) may be such that the functional groups in the resin fall within the above range.

The number average molecular weight of the resin (3) is 100
A range of 0 to 200,000, preferably 3,000 to 80,000 is desirable.

The hydroxyl group-containing resin (A) may be blended with the resin (3) as required.

The base resin may be, for example, a hydrocarbon solvent such as toluene or xylene, a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone, an ester solvent such as ethyl acetate or butyl acetate, or an ether such as dioxane or ethylene glycol diethyl ether. It is used in the form of a solution, a dispersion, a non-aqueous dispersion, etc. dissolved or dispersed in a solvent, an alcohol solvent such as butanol or propanol, or an aliphatic hydrocarbon such as pentane, hexane, or heptane.

[0072] The non-aqueous dispersion type base resin composition uses the resin (1), (2) or (3) as a dispersion stabilizer, and in the presence of the dispersion stabilizer, one or more radically polymerizable inorganic resins are added. Adding a saturated monomer and a polymerization initiator to an organic solvent that dissolves the monomer and dispersion stabilizer but not the polymer particles obtained from the monomer, and causing a polymerization reaction. It can be produced as a non-aqueous dispersion. When the resin used as the dispersion stabilizer is a mixture, that is, the resin (1
) or (2), the monomers are polymerized using some or all of the components of the resin mixture as a dispersion stabilizer, and when only some of the components of the resin mixture are used, the remaining components are then polymerized. By blending the ingredients, a non-aqueous dispersion is obtained. Examples of monomers that can be used to form the polymer serving as the particle component of the non-aqueous dispersion include all the monomers already described. Since the polymer serving as the particle component must not be dissolved in the organic solvent used, it is preferably a copolymer containing a large amount of highly polar monomer. i.e. methyl (meth)acrylate, ethyl (meth)
Acrylate, (meth)acrylonitrile, 2-hydroxy (meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylamide, acrylic acid, methacrylic acid, itaconic acid, styrene, vinyltoluene, α-methylstyrene, N-methylol ( It is preferable to contain a large amount of monomer such as meth)acrylamide. Further, the particles of the non-aqueous dispersion can be crosslinked if necessary. An example of a method for crosslinking the inside of the particles is a method of copolymerizing a polyfunctional monomer such as divinylbenzene or ethylene glycol dimethacrylate.

Although the organic solvent used for the non-aqueous dispersion does not substantially dissolve the dispersed polymer particles produced by the polymerization,
The above-mentioned dispersion stabilizer and radically polymerizable unsaturated monomer include those that serve as good solvents. In general, aliphatic hydrocarbons are preferably used in combination with aromatic hydrocarbons and alcohol-based, ether-based, ester-based, or ketone-based solvents as mentioned above. Furthermore, trichlorotrifluoroethane, metaxylene hexafluoride, tetrachlorohexafluorobutane, etc. can also be used if necessary.

Polymerization of the above monomers is carried out using a radical polymerization initiator. Examples of usable radical polymerization initiators include 2,2'-azoisobutyronitrile, 2
, 2'-azobis(2,4-dimethylvaleronitrile and other azo initiators; benzoyl peroxide, lauryl peroxide, tert-butyl peroctoate and other peroxide initiators; these polymerization initiators is generally 0.2 to 10 parts by weight per 100 parts by weight of monomers subjected to polymerization.
It can be used within the range of parts by weight. The formulation of the dispersion stabilizer resin to be present during the polymerization can be selected from a wide range depending on the type of resin, but in general, 3 parts by weight of the radically polymerizable unsaturated monomer are added to 100 parts by weight of the resin.
A suitable amount is about 240 parts by weight, preferably about 5 to 82 parts by weight.

In the present invention, the dispersion stabilizer resin and the polymer particles can also be combined.

[0076] In the non-aqueous dispersion resin composition described above, a solid phase consisting of polymer particles formed by polymerizing a radically polymerizable unsaturated monomer is stabilized in a liquid phase in which a dispersion stabilizer resin is dissolved in an organic solvent. It is a non-aqueous dispersion that can significantly increase the solid content during coating, and also forms a coating film with an excellent finished appearance without sagging or running due to the high viscosity after coating. can. Furthermore, the formed coating film has an organic silane group in the continuous phase of the coating film, and is photo and chemically stable.
Furthermore, since the polymer particle component in the coating film is stabilized by the continuous phase and the coating film is reinforced by the particle component, it has excellent mechanical properties such as impact resistance.

The curing catalyst used in the clear coating composition is used to promote the reaction of silane groups, epoxy groups, and hydroxyl groups in the resin, and includes metals such as aluminum, titanium, zirconium, calcium, and barium. Metal alkoxides in which an alkoxy group is bonded to metal alkoxides; metal chelate compounds in which a chelate compound capable of forming a keto enol tautomer is coordinated to the metal alkoxides; AlCl3, Al(C2H5)2Cl, TiCl4,
ZrCl4, SnCl4, FeCl4, BF3, BF3
: Lewis acids such as (OC2H5)2; protonic acids such as organic protonic acids (methasulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, etc.) and inorganic protonic acids (phosphoric acid, phosphorous acid, phosphinic acid, sulfuric acid, etc.) ; Compounds having Si-O-Al bonds such as aluminum silicate and the like can be suitably used. Among the above, metal chelate compounds are preferred, and furthermore, diisopropoxyethylacetoacetate aluminum, tris(ethylacetoacetate) aluminum, isopropoxy bis(ethylacetoacetate) aluminum, monoacetylacetonate bis(ethylacetoacetate) aluminum ,
Tris (n-propylacetoacetate) aluminum, tris (n-butylacetoacetate) aluminum, monoethylacetoacetate bis (acetylacetonate) aluminum, tris (acetylacetonate) aluminum, tris (propionyl acetonate)
Aluminum, aluminum chelate compounds such as acetylacetonate bis(propionyl acetonate) aluminum; diisopropoxy bis(ethyl acetoacetate titanium, diisopropoxy bis(
Titanium chelate compounds such as titanium (acetylacetonate); zirconium chelate compounds such as zirconium tetrakis(n-propylacetoacetate), zirconium tetrakis(acetylacetonato), zirconium tetrakis(ethylacetoacetate), etc. are suitable. .

The blending ratio of the curing catalyst is 0.01 to 30 parts by weight, preferably 0.1 parts by weight, based on 100 parts by weight of the resin.
~10 parts by weight. If the amount of the curing catalyst is less than 0.01 parts by weight, the curability and finish of the coating film will deteriorate, and if it exceeds 30 parts by weight, the finish and water resistance of the coating film will deteriorate, which is not preferable.

[0079] The clear paint composition may contain, if necessary,
UV absorbers, antioxidants, light stabilizers, and various other paint additives can be added.

[0080] In the method of the present invention, for example, a chemical conversion treated steel plate is coated with an electrodeposition paint, and an intermediate coat (sometimes omitted) is applied.
A colored base paint composition is applied to the paint film, which is coated with a primer suitable for various plastic materials, and an intermediate paint (sometimes omitted) is then applied with a top clear paint. This can be carried out by painting the composition. The above electrodeposition paint and intermediate coating paint usually have a coating content of 140 to 190, although it varies depending on the type of paint.
Bake for 30-90 minutes at ℃. Application of the pigmented base and top clear coating compositions can be carried out using conventional coating methods, such as electrostatic or non-electrostatic coating machines. Further, the thickness of the colored base coat is preferably about 10 to 50 μm (after curing). After applying the paint, it is left to stand at room temperature for several minutes, or it is force-dried at about 50 to 80°C for several minutes, and then a clear paint composition is applied. The thickness of the clear coating is 20
~100 μm (after curing) is preferred. Next, the object to be coated can be cured by heating at about 120 to 180° C. for about 30 to 90 minutes.

[0081]

[Operation and Effects of the Invention] In the method of the present invention, the paint for the colored base coat that is finished by the two-coat one-bake method is as follows:
Contains polyorganosiloxane having two or more silanol groups and/or alkoxysilane groups in one molecule as a binder component, and when heated, silanol groups (or silanol groups generated by hydrolysis of alkoxysilane groups) react with each other. The reaction between the silanol groups and the hydroxyl groups in the hydroxyl group-containing resin occurs rapidly at relatively low temperatures. Since this reaction occurs faster than the curing reaction of the clear coat paint, the viscosity of the base coat paint increases faster than that of the clear coat paint at the early stage of baking. For this reason, a base coating film is formed that can withstand the shrinkage force of the clear coating film due to the volume change caused by the curing of the clear coating material and the volatilization of the solvent, and as a result, it is thought that the finished appearance of the coating film is improved. Furthermore, when the colored base top coat paint was applied to the cured clear coat film and recoated, an improvement in the adhesion between the two coats was observed.

[0082]

[Examples] The present invention will be explained in more detail with reference to Examples below.

[0083] Hereinafter, "parts" and "%" mean "parts by weight" and "% by weight," respectively.

[0084]

[Production Example 1] 0.29 mol of isophthalic acid, 0.29 mol of phthalic acid.
23 mol, hexahydrophthalic acid 0.43 mol, trimethylolpropane 0.4 mol, neopentyl glycol 0.6 mol, and coconut oil fatty acid 0.1 mol were added to a reaction vessel and the acid value was determined by condensation polymerization at 200-230°C. 8. Hydroxyl value 7
A coconut oil-modified polyester resin No. 2 was obtained. 43 parts of xylene was added to 100 parts of the polyester resin to obtain a 60% by weight varnish (a-1). The viscosity was Y- (25°C, Gardner bubble viscosity).

[0085]

[Production Example 2] Diphenyldimethoxysilane
182 parts β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane 186
partially deionized water
108 parts 60% phosphoric acid
1
After reacting at 60°C for 15 hours, methanol was removed under reduced pressure and butyl acetate was added to reduce the solid content to 50%.
, Gardner viscosity G polyorganosiloxane liquid (b-
1) was obtained. The obtained polyorganosiloxane had a number average molecular weight of about 2000, and had an average of 10 silanol groups and an average of 7 epoxy groups per molecule.

[0086]

[Production Example 3] Phenyltrimethoxysilane
198 parts γ-glycidoxypropyltrimethoxysilane
236 parts deionized water
108 parts 60% sulfuric acid

After reacting at 60° C. for 10 hours, methanol was removed under reduced pressure and xylene was added to obtain a polyorganosiloxane liquid (b-2) with solid content of 50% and Gardner viscosity DE. The obtained polyorganosiloxane had a number average molecular weight of about 8,000, and had an average of 6 silanol groups and an average of 20 epoxy groups per molecule.

◎Colored base coat paint composition Base coat paint-1 100 parts (solid content: 60 parts) of the resin solution (a-1) obtained in Production Example 1, 33.3 parts of Yuban 20SE (Note 1) ( 20 parts (solid content), resin solution obtained in Production Example 2 (b-1)
A mixture of 40 parts (20 parts solids), 20 parts aluminum paste, and 1 part Raybow #3 (Note 2) was stirred, and then 20 parts of Swasol 1000 (Note 3) and ethyl acetate were mixed.
/80 (weight ratio) mixed solvent was added to reduce the paint viscosity to 15 seconds (
Ford Cup #4/20°C) was used for the test.

(Note 1) Yuban 20SE: manufactured by Mitsui Toatsu Chemical Co., Ltd., butyl etherified melamine resin solution with a solid content of approximately 60%, trade name.

(Note 2) Raybow #3: Silicone surface conditioner liquid manufactured by Raybow Chemical Co., Ltd., containing approximately 1% active ingredient.
Product name.

(Note 3) Swazol 1000: Cosmo Oil Co., Ltd., petroleum-based aromatic solvent, trade name.

Base coat paint-2 In base coat paint-1, resin solution (b-1)
Coating material 2 for base coat was obtained using the same formulation as coating material 1, except that resin solution (b-2) was used instead of resin solution (b-2).

Base coat paint-3 In base coat paint-1, resin solution (b-1)
A base coat paint-3 was obtained using the same formulation as the paint-1 except that the base coat paint-3 was not used.

[0093]

[Manufacturing example 4]

(Part) Methyltrimethoxysilane
2720 γ-methacryloxypropyltrimethoxysilane
256 Deionized water

1134 6%
hydrochloric acid

2 Hydroquinone

1 These mixtures were reacted at 80° C. for 5 hours to obtain a polysiloxane macromonomer. The number average molecular weight of the macromonomer is 200
0. On average, each molecule had one vinyl group (polymerizable unsaturated bond) and four hydroxyl groups. A resin composition was prepared using this polysiloxane macromonomer in the following manner.

[0094]

(Part) Polysiloxane macromonomer
100 2-hydroxyethyl acrylate
100 Alicyclic vinyl monomer (Note 4)
200 2-ethylhexyl methacrylate
500 Styrene

100
Azobisisobutyronitrile

The resin composition (c-
1) was obtained. The number average molecular weight of the resin was about 10,000.

(Note 4)

[0096]

[Chemical formula 9]

[0097]

[Manufacturing example 5]

(Part) γ-methacryloxypropyltrimethoxysilane
100 2-hydroxyethyl methacrylate
100 Alicyclic vinyl monomer (Note 4)

200 2-ethylhexyl methacrylate
500 Styrene

100 Azobisisobutyronitrile
A resin composition (c-2) was obtained by dropping the mixture of No. 50 into 1000 parts of an equal weight mixture of butanol and xylene at 120°C. The number average molecular weight of the resin was approximately 9,000.

[0098]

[Manufacturing example 6]

(Part) The above polysiloxane macromonomer
200 2-hydroxyethyl acrylate
100 2-ethylhexyl methacrylate
500 Styrene

200
Azobisisobutyronitrile
50
An equal weight mixture of butanol and xylol
00 parts at 120°C to obtain the resin composition (c-3).
I got it. The number average molecular weight of the resin was about 10,000.

0099

[Manufacturing example 7]

(Part) γ-methacryloxypropyltrimethoxysilane
200 2-hydroxyethyl methacrylate
100 2-ethylhexyl methacrylate
500 Styrene

200 Azobisisobutyronitrile
50 parts in 1000 parts of an equal weight mixture of butanol and xylene.
The mixture was added dropwise at 20°C to obtain a resin composition (c-4). The number average molecular weight of the resin was approximately 9,000.

[0100]

[Production example 8]

(Part) Alicyclic vinyl monomer (Note 4)
400 2-hydroxyethyl methacrylate
100 2-ethylhexyl methacrylate
400 Styrene

100
Azobisisobutyronitrile

The resin composition (c-
5) was obtained. The number average molecular weight of the resin was approximately 9,000.

◎Coating composition for clear top coat Coating composition for clear top coat (1 to 5) Blend in the proportions (solid content) shown in Table 1, and then add Swasol 1000.
The solution was diluted to a solid content of 50%.

[0102]

[Table 1]

[0103]

[Examples 1 to 10 and Comparative Example 1] Preparation of coated plate Dull steel plate (
After coating (25 μm) with epoxy resin-based cationic electrodeposition paint (chemical conversion treatment) and curing it by heating at 170°C for 30 minutes, Lugabake AM (trade name, Kansai Paint (trade name)) was applied as an intermediate coat.
Co., Ltd., polyester resin/melamine resin-based automotive paint) was applied to a dry film thickness of 30 μm.
Baked at 0°C for 30 minutes. The coated surface was then water sanded with #400 sandpaper, drained and dried, and the coated surface was wiped with petroleum benzene to prepare the material.

After applying the colored base coat paint by air spray painting, the clear top coat paint was applied immediately after 3 minutes. The film thickness is 15 to 20 each in dry film thickness.
μm and 35 to 45 μm. Then, it was left at room temperature for 10 minutes and then baked at 140° C. for 30 minutes. however,
In the recoatability test, the first time was baked at 160°C for 30 minutes, and the second time was baked at 120°C for 30 minutes. The coating performance and appearance are shown in Table 2.

[0105]

[Table 2]

Test method (*1) Appearance: The coating film was examined for wrinkles and wrinkles. ◎ No abnormality, ○ Slightly observed, × Many observed.

(*2) Image clarity: Image clarity measuring instrument (IMAG
E CLARITY METER, Suga Test Instruments Co., Ltd.
(manufactured by). The numbers in the table are ICM values from 0 to 100%
Takes a value within the range of , the larger the value is the sharpness of the image (image clarity)
If the ICM value is 80 or more, it indicates that the image clarity is extremely excellent.

(*3) Metallic feel: The glittering feeling and whiteness of the metal when viewed from the front were visually evaluated. ◎Shiny and white, △No sparkle and less white.
×There is no glitter and no whiteness at all.

(*4) Water resistance: After a sample coated plate was immersed in warm water at 40°C for 240 hours, the state of blistering on the coated surface was visually evaluated. ◎ No abnormality, △ Slightly observed, × Significantly observed.

(*5) Recoatability: The same base paint and clear paint as in Examples and Comparative Examples were coated on the surface of the coating film, and the coating film was baked at 120° C. for 30 minutes. Crosscuts are made in the resulting coating film using a cutter knife, and cellophane tape is pasted on the coating surface, which is then rapidly peeled off to determine the adhesion between the first and second coatings (clear coating/base coating). was evaluated. ◎ No peeling observed at all, △ Slight peeling observed, × Significant peeling observed.

Claims (1)

[Claims] Claim 1: In a top coating method in which a colored base coat and a clear top coat are sequentially formed on a material and finished using a two-coat, one-bake method, the coating composition for forming the colored base coat includes: (1) a hydroxyl group-containing polyester resin (2); Amino resin (3) Polyorganosiloxane having a number average molecular weight of 1000 or more and having an average of two or more silanol groups and/or alkoxysilane groups and an average of one or more epoxy groups in one molecule (4) Metal flake powder and/or A coating composition for forming a clear top coat using a coating composition containing mica powder and (5) an organic solvent as an essential component: (1) a silanol group and/or a hydrolyzable group directly bonded to a silicon atom; , a resin having a hydroxyl group and an epoxy group (2
A coating film forming method characterized by using a coating composition containing as essential components:) a curing catalyst; and (3) an organic solvent.