JPH0812931A - Topcoat forming method - Google Patents

Abstract

PURPOSE:To form a coating having excellent finish appearance, acid resistance, scratch resistance, weather resistance and other properties. CONSTITUTION:A topcoat forming method comprising forming a color base coat and a clear topcoat in that order on a base material, wherein the color base coat and/or the clear topcoat is formed by using a curable coating compsn. comprising (a) a resin having hydroxyl, carboxyl, and epoxy groups in its molecule, (b) a silicon compd. having at least one hydrolyzable group directly bonded to a silanol group and/or a silicon atom in its molecule, and (c) an org. solvent. as indispensable components.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for forming a top coating film, more specifically, finish and coating performance (acid resistance,
The present invention relates to a method for forming an overcoat coating film capable of forming a coating film having excellent scratch resistance and the like.

[0002]

2. Description of the Related Art In recent years, air pollution has progressed, and damage from acid rain such as forest death has become a serious social problem. However, coatings applied to articles used outdoors such as automobile exterior panels. Also in the film, there is a problem that the coating film is etched by acid rain, or the coating film is whitened or spotted. Therefore, there is a strong demand for a coating film having good acid resistance.

Further, an overcoat film, for example, an overcoat film applied to an automobile outer panel or the like is apt to be scratched due to collision with sand or dust during traveling, rubbing by a cleaning brush or the like, and deterioration of appearance. It has become one of the causes, especially black,
Scratches are very noticeable on a dark-colored coating such as navy blue or brown. Therefore, there is a strong demand for improving the scratch resistance of the top coating film.

At present, a method for forming a topcoat coating film is widely used in which an amino-curable coating composition containing a hydroxyl group-containing resin and a binder amino resin is used as a coating composition for forming a topcoat coating film. An overcoat film satisfying both the scratch resistance has not been obtained.

As a method of using a composition other than the above amino-curable coating composition, a coating composition prepared by mixing a resin having an epoxy group and a hydroxyl group with a cyclic acid anhydride such as methylhexahydrophthalic anhydride as a curing agent. Is used as a coating composition for forming an overcoat coating film, a method for forming an overcoat coating film is disclosed in JP-A-63-84673 and JP-A-63-8.
It is described in Japanese Patent No. 4674. However, these methods have the drawback that the finished appearance, acid resistance, scratch resistance, etc. of the coating film are poor.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, in the method for forming an overcoat coating film by sequentially forming a colored base coat and a clear top coat on a material, a curable coating composition for forming an overcoat coating film contains a hydroxyl group, a carboxyl group and an epoxy group in the same molecule. It was found that a coating film free from the above-mentioned drawbacks of the prior art can be formed by using a resin containing the above-mentioned resin, a specific silicon compound and an organic solvent, and completed the present invention.

That is, the present invention provides a method for forming a topcoat coating film by sequentially forming a colored base coat and a clear top coat on a material, wherein the colored base coat and / or the clear top coat is (a) a hydroxyl group, a carboxyl group and an epoxy. A resin containing a group in the same molecule, (b)
It is formed of a curable coating composition containing as an essential component a silicon compound having at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule and (c) an organic solvent. The present invention relates to a method for forming a top coat film.

In the present invention, the silanol group means a hydroxyl group directly bonded to a silicon atom, and the hydrolyzable group directly bonded to a silicon atom means a group which produces a silanol group by hydrolysis.

In the present invention, as the material for forming the colored base coat, for example, various metals, particularly steel plates (chemical conversion treatment, chemical conversion treatment and primer electrodeposition coating, chemical conversion treatment, primer electrodeposition coating) And intermediate coating), various plastics (surface-treated, surface-treated and primer-coated, surface-treated, primer-coated and intermediate-coated, etc., if necessary), combinations of these You can list the ones that you bought.

In the method of forming a top coating film of the present invention, either or both of the colored base coat and the clear top coat formed on the material contain (a) a hydroxyl group, a carboxyl group and an epoxy group in the same molecule. A curable coating composition containing a resin, (b) a silicon compound having at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule, and (c) an organic solvent as essential components. Has been formed.

Resin (a) in the above curable coating composition
Is a base resin containing a hydroxyl group, a carboxyl group and an epoxy group in the same molecule.

The carboxyl group in the resin (a) is one of the important constitutional requirements in the present invention. That is, the carboxyl group is composed of a hydroxyl group in the resin (a) and a silanol group in the silicon compound (b) (including a silanol group produced by hydrolysis of a hydrolyzable group directly bonded to a silicon atom). The function of accelerating the reaction and the reaction of silanol groups is recognized, and the effect of improving low temperature curability is obtained by this, and this carboxyl group reacts with the epoxy group, and a cured film with excellent performance such as acid resistance. Along with the formation of the carboxyl group, the carboxyl group is consumed in the reaction with the epoxy group, and the carboxyl group does not remain in the coating film or remains in a small amount, so that the coating film has water resistance, acid resistance, scratch resistance, and weather resistance. And so on.

The hydroxyl group in the resin (a) has a hydroxyl value of about 1
An amount in the range of 0 to 300, preferably about 20 to 200 is good. When the hydroxyl value is less than about 10, the low temperature curing property, durability and the like of the coating film are deteriorated, while when the hydroxyl value exceeds about 300, the number of unreacted hydroxyl groups remaining in the coating film is increased, so that the water resistance of the coating film is increased. It is not preferable because it deteriorates the properties.

The amount of the carboxyl group in the resin (a) is about 3 to 150, preferably about 5 to 80 in terms of acid value. When the acid value is less than about 3, low temperature curability and the like decrease,
On the other hand, if the acid value exceeds about 150, the water resistance and weather resistance of the coating film will deteriorate, which is not preferable.

The epoxy group in the resin (a) is in an amount such that the epoxy value is in the range of about 0.1 to 4.0, preferably about 0.2 to 3.0. When the epoxy value is less than about 0.1, the low temperature curability is deteriorated, while when the epoxy value is more than about 4.0, the acid resistance and weather resistance of the coating film are deteriorated, which is not preferable.

The resin (a) has a number average molecular weight of about 30.
00-200000, preferably about 5000-8000
The range of 0 is good. When the number average molecular weight is less than about 3,000, the durability of the coating film is deteriorated, while when the number average molecular weight is more than about 200,000, an organic solvent (c) necessary for dilution is obtained.
It is not preferable because there is a drawback that the solid content of the coating material becomes low due to the large amount.

The type of the resin (a) is not particularly limited, and conventionally known ones can be appropriately selected and used, but acrylic resins are preferable from the viewpoint of weather resistance and durability of the coating film. .

Specific examples of the acrylic resin include, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, (poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol. Hydroxyl group-containing acrylic monomers such as mono (meth) acrylates and their adducts with caprolactone (ε-caprolactone etc.); (meth) acrylic acid,
(Anhydrous) maleic acid and other carboxyl group-containing ethylenically unsaturated monomers; glycidyl (meth) acrylate,
Glycidyl group-containing monomers such as methyl glycidyl (meth) acrylate and allyl glycidyl ether, 3,4-
A radically polymerizable epoxy group-containing monomer such as an alicyclic epoxy group-containing monomer such as epoxycyclohexylmethyl (meth) acrylate is used as an essential monomer component, and if necessary, other radically polymerizable unsaturated monomers,
For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate and cyclohexyl (meth).
C _1-24 alkyl (meth) acrylates or cycloalkyl (meth) acrylates such as acrylates; aromatic vinyl monomers such as styrene and vinyltoluene; nitrile compounds such as (meth) acrylonitrile; (meth)
Those obtained by copolymerizing other ethylenically unsaturated monomers such as amide compounds such as acrylamide and N-methylol (meth) acrylamide are included.

Further, as a method for synthesizing the resin (a), it is obtained by copolymerizing the above-mentioned hydroxyl group-containing acrylic monomer, the above-mentioned radical-polymerizable epoxy group-containing monomer and, if necessary, other radical-polymerizable unsaturated monomers. Also included is a method in which a cyclic acid anhydride (A-2) is subjected to a ring-opening half-esterification reaction with the hydroxyl group of the epoxy group-containing resin (A-1). The cyclic acid anhydride (A-2) used at that time is a compound having one or more carboxylic acid cyclic acid anhydride groups in one molecule, and examples thereof include phthalic anhydride, succinic anhydride, and tetrahydrophthalic anhydride. Acid, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, het anhydride, hymic acid anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride and the like,
These can be used alone or in combination of two or more.

The ring-opening half-esterification reaction between the hydroxyl group of the resin (A-1) and the cyclic acid anhydride (A-2) is modeled as follows: 1 mole of the hydroxyl group of the cyclic acid anhydride (A-2). This is a reaction in which moles react to open the cyclic acid anhydride group to generate 1 mole of a free carboxyl group. This ring-opening half-esterification reaction can be carried out by a method known per se,
For example, it can be performed in an organic solvent at a temperature of about 40 to about 100 ° C. At that time, a catalyst such as an organic tin compound, an organic titanium compound, or an organic zirconium compound can be used to accelerate the reaction.

The silicon compound (b) in the curable coating composition used in the present invention has at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule, It is a cross-linking agent component of the resin (a).

The hydrolyzable group is a residue which is hydrolyzed in the presence of water to form a silanol group, and examples thereof include C _1-3 alkoxyl groups such as methoxy, ethoxy and propoxy, acetoxy and propionyloxy. And the like acyloxy group and the like.

Examples of the silicon compound (b) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane,
If necessary, a radically polymerizable unsaturated group-containing silicon compound such as β- (meth) acryloyloxyethyltrimethoxysilane may be added to, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate. , (Poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol mono (meth) acrylate, and hydroxyl group-containing acrylic monomers such as adducts of these with caprolactone (ε-caprolactone etc.), (meth )
Acrylic acid, carboxyl group-containing ethylenically unsaturated monomers such as (anhydrous) maleic acid, glycidyl (meth) acrylate, methylglycidyl (meth) acrylate,
Glycidyl group-containing monomers such as allyl glycidyl ether, radically polymerizable epoxy monomers such as alicyclic epoxy group-containing monomers such as 3,4-epoxycyclohexylmethyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meta)
C _1-24 alkyl (meth) acrylate or cycloalkyl (meth), such as acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate and cyclohexyl (meth) acrylate. ) Acrylates, aromatic vinyl monomers such as styrene and vinyltoluene, nitrile compounds such as (meth) acrylonitrile, and other ethylenic compounds such as amide compounds such as (meth) acrylamide and N-methylol (meth) acrylamide. A polymer obtained by a radical polymerization reaction with a saturated monomer, preferably having an average molecular weight of about 3,000 to
In the range of about 200,000; General formula Si (OR) ₄ (I) (wherein R is the same or different, is a hydrogen atom or C _1-3.
Is an alkyl group. ) A silicon monomer represented by the formula; a low condensate of the silicon monomer; a low condensate of the silicon monomer, wherein a part of R in the low condensate is C _4-24 (preferably C _4-8 ). A modified silicon condensate substituted with a monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond);
Or obtained by reacting the modified silicon condensate with an ethylenically unsaturated monomer containing a functional group capable of reacting with one ethylenically unsaturated group and SiOR group (R is the same as above) in one molecule. A silicon condensate containing an ethylenically unsaturated group,
Polymers obtained by radical polymerization reaction with the above-mentioned other ethylenically unsaturated monomers, if necessary, preferably having an average molecular weight of about 3,000 to 200,000 are included.

In the above-mentioned silicon compound (b), a low condensation product of silicon monomer and a modified silicon condensation product can form a coating film having high solid content, low cost and various performances, and thus can be advantageously used. . Further, when a modified silicon condensate or a polymer using the same is used as the silicon compound (b), the resulting coating film is particularly advantageous in that it has excellent finish and acid resistance.

The low condensate of the above-mentioned silicon monomer is about 2-1 obtained by subjecting the above-mentioned silicon monomers to a condensation reaction.
A 00-mer, preferably about 2 to 10-mer, is suitable. Examples of the low-condensation product of the silicon monomer include "Colcoat ES40" (trade name, manufactured by Colcoat Co., Ltd., hereinafter, similarly, 1 to 10 mer of tetraethyl silicate, average of about 5 mer), "Colcoat MS51" (tetramethyl silicate). 1 to 10 mer, average about 4 mer) and the like. These low-condensates made by Colcoat are generally

[0026]

Embedded image

It is considered to have a structure of (n is 1 to 10).

The C _4-24 monovalent hydrocarbon group in the modified silicon condensate is, for example, a cyclic or linear branched chain such as butyl, pentyl, hexyl, heptyl, octyl, decyl, stearyl, cycloalkyl and the like. It includes an optionally substituted alkyl group, an aryl group such as phenyl, toluyl, xylyl and the like, an aralkyl group such as benzyl (an alkyl group substituted with an aryl group) and the like.

The hydrocarbon group containing an ether bond is, for example,

[0030]

Embedded image

(In the formula, m is 1, 2 or 3, p is 1 or 2, and _R'is a C _1-8 alkyl group.),

[0032]

Embedded image

(In the formula, m has the same meaning as described above.)
Etc. are included. In particular,

[0034]

[Chemical 4]

And the like.

The hydrocarbon group containing an ester bond is, for example,

[0037]

Embedded image

(In the formula, R ″ represents a C _1-8 cyclic or linear alkyl group which may be branched, an aryl group or an aralkyl group, and m represents the same meaning as described above. .)
Etc. are included. In particular,

[0039]

[Chemical 6]

And the like.

Further, the hydrocarbon group containing both ether bond and ester bond is, for example,

[0042]

[Chemical 7]

(In the formula, q is an integer of 2 or more, preferably 2
Is an integer of 10 and m and R ″ have the same meanings as described above.) And the like.

[0044]

Embedded image

And the like.

The modified silicon condensate is obtained, for example, by subjecting a monomer in which a part of R in the silicon monomer is replaced by a C _4-24 monovalent hydrocarbon group as a starting material, and subjecting this to a condensation reaction, or low condensate with C _4-24 alcohol (ether bond and / or may contain an ester bond) and the hydrocarbon part of the R of Teichijimigobutsu by dealcoholization C _4-24 of the silicon monomer It can be produced by substituting with a group.

The polymer of the ethylenically unsaturated group-containing silicon condensate is a functional group capable of reacting with the SiOR group contained in the low-condensation product of the silicon monomer or the modified silicon condensate (for example,
An ethylenically unsaturated monomer having one or more active hydrogen groups such as hydroxyl groups in one molecule and one ethylenically unsaturated group in one molecule is a low condensation product of silicon monomers and / or modified silicon condensation. Alcohol reacts with the substance to produce the SiOR
After substituting a part of R of the group with an ethylenically unsaturated monomer to produce an ethylenically unsaturated group-containing silicon condensate containing an average of about 1 ethylenically unsaturated group in one molecule, this is used alone Or by radical polymerization reaction of this with the other ethylenically unsaturated monomer.

Examples of the ethylenically unsaturated monomer having a functional group that reacts with the SiOR group and an ethylenically unsaturated group include, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, (Poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol (meth) acrylate, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether,
Hydroxyl vinyl ether, (poly) ethylene glycol monoallyl ether, and hydroxyl group-containing ethylenically unsaturated monomers such as adducts of these with caprolactone are preferred.

When a polymer is used as the silicon compound (b), if the average molecular weight is less than about 3,000, the coating performance such as acid resistance tends to decrease, while about 20,000.
When it exceeds 0, the solid content of the coating composition tends to decrease and the finished appearance of the coating film tends to deteriorate, such being undesirable.

The above-mentioned components (a) and (b) are preferably blended in the following proportions. The ratio is a value based on the total measurement of the components (a) and (b).

Component (a): Approximately 30 to 98% by weight, preferably about 50 to 95% by weight. When the amount is less than about 30% by weight, the amount of the base resin component in the composition decreases, so that the coating film is finished. The appearance and performance are deteriorated, while if it exceeds about 98% by weight, the solid content of the resin composition is decreased and the curability is decreased, which is not preferable.

Component (b): About 2 to 70% by weight, preferably about 5 to 50% by weight, and if it is out of the range, the curability is deteriorated, which is not preferable.

The organic solvent (c) in the curable coating composition used in the present invention is a component which dissolves or disperses the components (a) and (b). The organic solvent (c) is not particularly limited as long as it can dissolve or disperse the components (a) and (b), and can be appropriately selected and used from conventional organic solvents.

Specific examples of the organic solvent (c) include aromatic hydrocarbons such as toluene and xylene, acetone,
Examples thereof include ketone systems such as methyl ethyl ketone and methyl isobutyl ketone, ester systems such as ethyl acetate, propyl acetate and butyl acetate, and alcohol systems such as ethylene glycol monobutyl ether.

The organic solvent (c) is added so that the solid content of the resin composition is usually in the range of about 10 to 70% by weight.

In the curable coating composition used in the present invention, in addition to the components (a) to (c) described above, if necessary, a curing catalyst, an extender pigment, an ultraviolet absorber, an ultraviolet stabilizer, a fluidity modifier. And other paint additives and the like can be blended.

The curable coating composition used in the present invention is
It is used as a coating composition for a colored base coat by blending a coloring pigment in addition to the components (a) to (c) described above.

Examples of the color pigments include quinacridone-based pigments such as quinacridone red, azo-based pigments such as pigment red, phthalocyanine-based pigments such as phthalocyanine blue and phthalocyanine green, inorganic powder pigments such as titanium oxide and carbon black, and aluminum. flake,
Inorganic flake pigments such as nickel flakes, copper flakes, brass flakes, chrome flakes, pearl mica, colored pearl mica and the like can be mentioned.

The curable coating composition used in the present invention can be used as it is as a coating composition for a clear top coat. In addition, the above-mentioned coloring pigment may be added to the clear topcoat coating composition, if necessary, to such an extent that the previously applied colored base coat is not completely hidden.

The method of the present invention is a method for forming a topcoat coating film in which a colored basecoat and a clear topcoat are sequentially formed on a material, and one or both of the colored basecoat and the clear topcoat are topcoat paint compositions. It is formed by the curable coating composition used as.

In particular, the curable coating composition is acid resistant,
Since it is possible to form a coating film having excellent scratch resistance and the like, it is preferably used for a clear top coat. Further, the composition has excellent low temperature curability.

The method of the present invention is particularly suitable as a method for forming a top coat film for automobiles, home electric appliances and the like.

The method of forming the top coating film of the present invention is a coating system known in the fields of automobile industry, home appliance industry, etc., for example, 2 coat 1 bake system or 2 coat 2 bake system of colored base coat / top clear coat. And a method of finishing colored base coat / top clear coat / top clear coat by 3 coat 1 bake system or 3 coat 2 bake system.

Of these methods, the method of finishing by the two-coat one-bake method is particularly preferable. Hereinafter, as a typical example, a coating method by the two-coat one-bake system using the curable coating composition for a clear top coat will be described.

First, a coating composition for a colored base coat is applied onto the above-mentioned material by ordinary spray coating.

As a coating composition for a colored base coat,
A composition in which a color pigment is added to the curable coating composition or a coating composition for a colored base coat known per se for automobiles is used.

Examples of the known coating composition for colored base coat include acrylic resin / amino resin type, alkyd resin / amino resin type, polyester resin / amino resin type, acrylic resin / polyisocyanate type, alkyd resin / polyisocyanate. Examples of the coating composition include a curable composition such as a polyester resin, a polyester resin / polyisocyanate system, and the like, and a color pigment. Here, as the amino resin, it is particularly preferable to use a melamine resin or the like.

The form of the known coating composition for colored base coat is not particularly limited, and may be any form such as organic solvent solution type, non-aqueous dispersion type, aqueous solution type, water dispersion type, high solid type and the like. Can be used.

As the equipment used for spray coating, there are an ordinary air spray gun, an airless spray gun, an air spray type electrostatic coating machine, an airless spray type electrostatic coating machine, a rotary atomizing type electrostatic coating machine and the like. Can be used.

The film thickness of the coating composition for colored base coat is
After curing, it is preferably in the range of about 10 to 30 μm.

After coating the coating composition for a colored base coat, the coating composition is left at room temperature for a few minutes or forcedly dried at a temperature in the range of about 50 to 80 ° C. for a few minutes, and then the curable coating composition Clear Apply the topcoat coating composition.

The coating method and coating equipment for the clear topcoat coating composition may be the same as those for the colored basecoat coating composition.

The film thickness of the clear topcoat coating composition is preferably in the range of about 20 to 80 μm after curing.

Next, both the colored base coat and the clear top coat are simultaneously heat-cured. It is suitable that the heating conditions are usually about 100 to 180 ° C. and about 10 minutes to 2 hours.

[0075]

EFFECTS OF THE INVENTION According to the method for forming a top coating film of the present invention, by using a specific curable coating composition as the top coating composition, in particular, the finished appearance, acid resistance, scratch resistance,
A coating film having excellent weather resistance can be formed.

[0076]

EXAMPLES The present invention will be described more specifically below with reference to production examples, examples and comparative examples.

Production Example 1 Production of Resin Containing Hydroxyl Group, Carboxyl Group and Epoxy Group (a) 2-Hydroxyethylmethacrylate 130 g Acrylic acid 36 g Glycidylmethacrylate 142 g Isobutylmethacrylate 492 g Styrene 200 g Azobisdimethylvaleronitrile 70 g A mixture of xylene at 80 ° C. Drop into 1000g, 5
Acrylic polyol having a number average molecular weight of 8000 (hydroxyl value = 56, acid value = 25, epoxy value =
0.95) was obtained.

Production Example 2 Production of Resin (B) Containing Hydroxyl Group, Carboxyl Group and Epoxy Group 260 g of 2-hydroxyethyl methacrylate, 284 g of glycidyl methacrylate, 200 g of styrene and n
2,000 g of a 50% xylol solution of acrylic polyol (number average molecular weight 8500) consisting of 256 g of butyl methacrylate was mixed with 148 g of phthalic anhydride and 0.5 g of butyltin laurate, and the ring-opening reaction of acid anhydride group was carried out at 50 ° C. for 6 hours. And the number average molecular weight of 10,000
Acrylic polyol (hydroxyl value = 49, acid value = 48,
Epoxy value = 1.72) was obtained.

Production Example 3 Production of Resin (C) Containing Hydroxyl Group, Carboxyl Group and Epoxy Group 2-hydroxyethyl acrylate 290 g, 3,4-
Epoxy cyclohexyl methyl methacrylate 294g
And xylol 5 of acrylic polyol (number average molecular weight 9000) consisting of 416 g of n-butyl methacrylate
2000 g of 0% solution was mixed with 100 g of succinic anhydride and 0.5 g of butyltin laurate, and ring-opening reaction of acid anhydride group was performed at 50 ° C. for 6 hours to give a number average molecular weight of 10
000 acrylic polyols (hydroxyl value = 158, acid value = 50, epoxy value = 1.35) were obtained.

Production Example 4 Production of Resin (d) Containing Hydroxyl Group and Carboxyl Group Acrylic acid 108 g 2-hydroxyethyl acrylate 232 g Styrene 300 g n-butyl acrylate 360 g Azobisisobutyronitrile 20 g A mixture of 1000 g of xylene at 110 ° C. Dripping,
The reaction was carried out for 8 hours to obtain an acrylic polyol having a number average molecular weight of 20,000 (hydroxyl value = 112, acid value = 84).

Production Example 5 Production of hydroxyl group- and epoxy group-containing resin (e) 2-hydroxyethyl acrylate 232 g Glycidyl methacrylate 284 g Styrene 200 g 2-Ethylhexyl methacrylate 284 g Azobisisobutyronitrile 20 g Mixture in 110 g xylene 1000 g. Dripping,
Acrylic polyol having a number average molecular weight of 20,000 after reacting for 8 hours (hydroxyl value = 112, epoxy value = 2.0)
I got

Production Example 6 Production of Silicon Compound γ-methacryloxypropyltrimethoxysilane 375 g n-butyl acrylate 625 g Azobisisobutyronitrile 20 g A mixture of the above was added dropwise to xylene 1000 g at 110 ° C.
The reaction was carried out for 8 hours to obtain a silicon compound which was an acrylic resin having a number average molecular weight of 20,000 (average of 30 alkoxysilane groups in one molecule).

Production Example 7 Production of Silicon Compound “Colcoat ES40” 850 g 2-hydroxyethyl methacrylate 150 g Tris (acetylacetonato) aluminum 0.1 g Hydroquinone 1 g A mixture of 53 g was deethanolized at 120 ° C. for 3 hours to give 1 A silicon-containing monomer having an average of one unsaturated bond in the molecule was obtained.

Next, a mixture of the above-mentioned silicon-containing monomer 300 g hydroxyethyl acrylate 232 g n-butyl methacrylate 468 g azobisisobutyronitrile 30 g was added dropwise to 1000 g of xylene at 100 ° C. 8
The reaction was carried out for a time to obtain a silicon compound which is an acrylic resin having a number average molecular weight of 15,000.

Production Example 8 Production of Silicon Compound “Colcoat ES40” 530 g Benzyl alcohol 470 g Tris (acetylacetonato) aluminum 0.1 g A mixture of 200 g was subjected to deethanolation reaction at 160 ° C. for 6 hours to obtain a silicon compound. This product has 6 out of 12 ethoxy groups on average in one molecule.

[0086]

[Chemical 9]

Is replaced by.

Production Example 9 Production of Silicon Compound “Colcoat ES40” 705 g Hydroxyethyl acetate 295 g Tris (acetylacetonato) aluminum 0.1 g A mixture of 44 g was deethanolized at 160 ° C. for 6 hours to obtain a silicon compound. . This one has 3 out of 12 ethoxy groups on average in one molecule.

[0089]

[Chemical 10]

Has been replaced by.

Production Example 10 Production of Clear Topcoat Coating Compositions Based on the compounding ratios shown in Table 1, clear topcoat coating compositions (a-1) to (a-18) were produced. Among these coating compositions, (a-1) to (a-1
2) is for the method of the present invention, and includes (a-13) to (a)
-18) is for comparison.

Production Example 11 Production of Colored Basecoat Coating Compositions (b-1) to (b-5) Based on the compounding ratios shown in Table 1, colored basecoat coating compositions (b-1) to (b). -4) was produced.

[0093]

[Table 1]

In Table 1 above, all blending ratios are in g (solid content). The aluminum paste is "Alpaste 4919" (trade name, Toyo Aluminum Co., Ltd.).
Manufactured, aluminum flakes, solid content 65% by weight).

75 g of the resin (b) obtained in Production Example 2
(Solid content), "Uban 20SE" (trade name, manufactured by Mitsui Toatsu Co., Ltd., butylated melamine resin, solid content 60% by weight)
25 g (solid content) and 8 g of "Alpaste 4919"
The (solid content) was mixed to produce a coating composition (b-5) for colored base coat.

Production Example 12 Preparation of Material A dull steel sheet (chemical conversion treated) was coated with "Electron No. 940".
0 "(trademark, manufactured by Kansai Paint Co., Ltd., an epoxy resin-based cationic electrodeposition coating) is applied to a cured film thickness of 25 μm, heat-cured at 170 ° C. for 30 minutes, and then“ ES Primer Surfacer TP-37 "
(Trade name, manufactured by Kansai Paint Co., Ltd., polyester resin /
Cured melamine resin-based intermediate coating for automobiles)
It was coated so as to have a thickness of 0 μm, and cured by heating at 140 ° C. for 30 minutes. Next, the coating film was water-polished with # 400 sandpaper, drained and dried, and the coated surface was wiped with petroleum benzine as a material.

Example 1 Two-coat one-bake coating was applied by the following steps.

Colored base coat coating composition (b-5)
Xylol paint viscosity 14 seconds (Ford Cup No.
4, 20 ° C., which has the same meaning below), was applied to the material prepared in Production Example 12 with a cured film thickness of about 15 μm.
m was spray-painted to form a colored base coat on the material.

Next, after the colored base coat was allowed to stand for 3 minutes, the clear top coat coating composition (a-1) was adjusted to a coating viscosity of 25 seconds with xylol so that the cured film thickness was about 40 μm. Was spray coated onto the colored base coat to form a clear top coat.

Next, both the above-mentioned colored base coat and clear top coat coating films were simultaneously heat-cured at 120 ° C. for 30 minutes to form a top coating film.

Examples 2 to 17 and Comparative Examples 1 to 6 Using the coating composition for colored base coat and the coating composition for clear top coat described in Table 2, the same procedure as in Example 1 was carried out by the two-coat one-bake method. Painting was performed to form a top coating film.

Next, with respect to the top coating films formed in the above Examples and Comparative Examples, the finishing properties (appearance, appearance,
Gloss, image clarity) and coating film performance tests were conducted.

Appearance: The presence or absence of abnormal surface conditions (glint, tinge, cracks, peeling, opacity (smudge)) was examined.

Gloss: 60 ° specular reflectance (%) was measured.

Image clarity: Measured using a "PGD-IV type meter" (produced by Japan Color Research Laboratory, image clarity measuring instrument). The larger the value, the better the sharpness.

Solvent resistance: The coated surface was wiped 10 times with gauze soaked with xylol, and then the coated surface was observed and evaluated according to the following criteria.

◯ indicates that there is no change, Δ indicates that scratches are noticeable on the coated surface, and x indicates that the coated surface swells and tends to whiten.

Adhesion: about 1.5 m with a knife on the coated surface
Make 11 vertical and horizontal cuts with a width of m. Next, a cellophane adhesive tape having a width of 24 mm was brought into close contact with the adhesive tape, and the number of adhered streaks remaining when strongly peeled off was examined. The evaluation criteria are as follows.

◯ indicates the remaining number is 100, and Δ indicates the remaining number is 9.
9 to 95, and x indicates that the remaining number is 94 or less, respectively.

Scratch resistance: It was examined using a dyed product friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho). Kneading polishing powder (Dharma cleanser) with water and placing it on the coated surface, holding it on the tester terminal and applying a load of 0.5 kg, 25
Rub back and forth, and evaluated based on the following criteria.

⊚ indicates that there is no change compared to the initial gloss, ◯ indicates slight glossiness compared to the initial glossiness, and Δ indicates glossiness compared to the initial glossiness. That is, x indicates that gloss was remarkably generated as compared with the initial gloss.

Acid resistance: 0.4 cc of 40% by weight sulfuric acid water was dropped on the coated surface, dried at 75 ° C. for 15 minutes and washed with water,
The depth (μm) of the dropped sulfuric acid trace (etching) was measured.

Weather resistance: QUV weather meter (UV fluorescent lamp "No. QFS-40, U
V-B ", wavelength range 320 to 280 nm), the degree of coating film deterioration was observed after repeating a cycle of irradiation (15 minutes) and condensation (15 minutes) at a temperature of 40 to 70 ° C. for 2000 hours.

The test results are shown in Table 2.

[0115]

[Table 2]

[0116]

[Table 3]

[0117]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasumasa Okumura 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. (72) Inventor Yoshihiko Aida 4--17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Nishi Paint Co., Ltd. (72) Inventor Shigerou Nishiguchi 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd. (72) Inventor Ri Isozaki 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Within the corporation

Claims (11)

[Claims] 1. A method of forming a topcoat coating film comprising a colored base coat and a clear top coat sequentially formed on a material, wherein the colored base coat and / or the clear top coat have the same molecule (a) hydroxyl group, carboxyl group and epoxy group. A resin contained therein, (b) a silicon compound having at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule, and (c) a curable composition containing an organic solvent as essential components A method for forming an overcoat coating film, which is formed of a coating composition. 2. A method for forming a topcoat coating film, comprising forming a colored basecoat on a material, forming a clear topcoat on the surface of the basecoat without curing, and then curing both coating films by heating to form two coats. The method for forming a topcoat coating film according to claim 1, wherein the method is a one-baking method. 3. The method for forming a topcoat coating film according to claim 1, wherein both the colored base coat and the clear top coat are the curable coating composition. 4. The method for forming a topcoat coating film according to claim 1, wherein the colored base coat is a coating composition in which a color pigment is mixed with an acrylic resin / amino resin-based curable composition. 5. The method for forming a topcoat coating film according to claim 1, wherein the resin (a) has a hydroxyl value of 10 to 300, an acid value of 3 to 150, and an epoxy value of 0.1 to 4.0. 6. The resin (a) is obtained by ring-opening half-esterification reaction of a cyclic acid anhydride with a hydroxyl group of a resin containing a hydroxyl group and an epoxy group in the same molecule. The method for forming a topcoat coating film according to claim 1 or 5. 7. A silicon monomer and / or a silicon compound (b) represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). The method for forming an overcoat coating film according to claim 1, which is the low condensation product. 8. A low-condensation silicon compound (b) represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). A thing,
Further, it is a modified silicon condensate in which a part of R in the low condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond). The method for forming an overcoat coating film according to claim 1, wherein: 9. A silicon compound (b) is a low condensation of a silicon monomer represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). Ethylenically unsaturated group obtained by reacting a compound with an ethylenically unsaturated monomer having a functional group that reacts with one ethylenically unsaturated group and SiOR group (R is the same as above) in one molecule The method for forming an overcoat coating film according to claim 1, which is a radical polymer containing the contained silicon condensate as a monomer component. 10. A low-condensation silicon compound (b) represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). A thing,
Further, a modified silicon condensate in which a part of R in the low condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond) and 1 Ethylenically unsaturated group-containing silicon condensation obtained by reacting an ethylenically unsaturated monomer having a functional group that reacts with one ethylenically unsaturated group and a SiOR group (R is the same as above) in the molecule The method for forming a topcoat coating film according to claim 1, which is a radical polymer containing a substance as a monomer component. 11. The method for forming a topcoat coating film according to claim 9, wherein the ethylenically unsaturated monomer is a hydroxyl group-containing ethylenically unsaturated monomer.