JP2000345102A - Hardening composition and coating with the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hardening composition having excellent compatibility, and capable of forming a highly hard coating membrane having excellent acid resistance and abrasion resistance at the same time by formulating a specific self-curing resin and an inorganic oxide colloid dispersion. SOLUTION: This composition contains (A) a self-curing resin having carboxyl groups and epoxy groups in one molecule and (B) an inorganic oxide colloid dispersion. Further, it is preferable that the component A has an acid value of 30-110 mgKOH/g, an epoxy content of 0.5-2.5 mmol/g, a number average molecular weight of 1,000-30,000, an equivalent ratio of the acid/epoxy of the component A of 0.7-1.3 and a compatibility parameter of 9.0-11.0. The component A is preferably obtained, for example, by copolymerizing an epoxy group- containing monomer and a carboxylic group-containing monomer such as (meth) acrylic acid, maleic acid, itaconic acid, fumaric acid or mesaconic acid as essential components at a low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition capable of forming a coating film having high acidity and abrasion resistance and high hardness without causing bumps and whitening, and a coating film using the same. About the method.

[0002]

2. Description of the Related Art In the past, paints for overcoating such as automobile outer panels have been mainly of a type in which a hydroxyl group-containing acrylic resin is cured by heating with a melamine resin. However, in recent years, etching of a coating film and stain-like stains due to acid rain have become problems worldwide. Further, with the spread of car wash machines, there has been a demand for a top coat paint, particularly a clear top coat paint, capable of forming a coating film having scratch resistance simultaneously with the car wash machine.

[0003] The imparting of scratch resistance to a coating film is usually achieved by making the coating film highly crosslinked. On the other hand, the application of acid resistance to a coating film is achieved by introducing a cross-linking system that is resistant to acid.However, a method of imparting acid resistance and simultaneously imparting scratch resistance to a coating film has been conventionally used. Few have been proposed.

[0004] For example, Japanese Patent Application Laid-Open No. 2-227553 discloses that an acrylic resin having a high hydroxyl value is baked in the presence of a monomeric melamine resin and an acid catalyst to form a highly crosslinked density coating film, and a high degree of scratch resistance can be obtained. Is described.
However, this crosslinked system has a drawback that the acid resistance is inferior due to the fact that the crosslinked coating film of the melamine resin is easily decomposed with an acid.

[0005] As a method for introducing another acid-resistant cross-linking system into the acid-sensitive melamine resin cross-linking system to achieve both acid resistance and scratch resistance of the coating film, carboxyl groups / epoxy groups / hydroxyl groups / Complex cross-linking system of melamine resin
No. 247264) and a complex crosslinking system of a hydroxyl group / alkoxysilyl group / melamine resin (JP-A-4-816383).
Nos. 1 and 2, but the improvement in acid resistance was not always sufficient due to the use of a melamine resin.

On the other hand, as a cross-linking system using no melamine resin, a cross-linking system consisting of only a carboxyl group / epoxy group or a carboxyl group / epoxy group / hydroxyl group (JP-A-62-87288, JP-A-2-4557).
No. 7, JP-A-3-287650), these systems are excellent in acid resistance of the coating film, but have insufficient scuff resistance because the cured coating does not have a high crosslinking density. There is a disadvantage that there is.

Therefore, a method of adding colloidal silica to a thermosetting resin in order to impart abrasion resistance and high hardness is known. (JP-A-57-128760) However, the acid resistance was not sufficient.

Further, an organic solvent-based thermosetting paint containing a mixture of a carboxyl group-containing resin and an epoxy group-containing resin as a main component, to which colloidal silica is added (Japanese Patent Laid-Open No.
-298460), but the finished appearance of the initial coating film is good, but there is a drawback that when the coating material is stored, gels and lumps easily appear and the coating film is easily whitened.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, it is to provide a novel curable composition.

Another object of the present invention is to provide a curable composition having good compatibility and capable of forming a high-hardness coating film having excellent acid resistance and scratch resistance at the same time.

That is, the present invention provides a curable composition comprising a self-curable resin containing a carboxyl group and an epoxy group in one molecule and a colloidal dispersion of an inorganic oxide. is there.

[0012] The present invention also relates to an organic solvent-based thermosetting paint as an uppermost clear paint when forming at least one kind of colored paint and at least one kind of clear paint sequentially to form a multi-layer top coat. An object of the present invention is to provide a method for forming a multilayer overcoat film characterized by using a composition.

The self-curable resin used in the curable composition of the present invention has a basic skeleton of a vinyl resin or a polyester resin, and has a carboxyl group, a terminal and / or a main chain and a side chain in one molecule. In addition, the resin is a resin containing one or more epoxy groups at the same time, and the two functional groups react with each other to crosslink and cure, so that the compounding of the crosslinking agent can be omitted.

Such a method for producing a self-curing resin can be produced, for example, by the following method.

(1) An epoxy group-containing monomer and a carboxyl group-containing monomer such as (meth) acrylic acid, maleic acid, itaconic acid, fumaric acid and mesaconic acid are copolymerized at a low temperature as essential components.

(2) After copolymerizing an epoxy group-containing monomer and a hydroxyl group-containing monomer as essential components, the hydroxyl group and an acid anhydride (phthalic anhydride, succinic anhydride, hymic anhydride, hexahydrophthalic anhydride, , Methylhexahydrophthalic anhydride, etc.) at low temperatures by a half esterification reaction.

(3) A carboxyl group-containing monomer and an epoxy group-containing monomer obtained by previously adding a hydroxyl group-containing monomer and the above-mentioned acid anhydride by a half esterification reaction, as essential components. Copolymerizes at low temperature.

(4) An acid anhydride monomer having a polymerizable unsaturated bond (for example, maleic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, hymic anhydride, etc.) and an epoxy group-containing monomer are essential. After copolymerization as a component, water and alcohol are added at a low temperature by a half esterification reaction. (5) A vinyl resin obtained by copolymerizing an epoxy group-containing monomer as an essential component and a carboxyl group Is produced by reacting a resin containing at a ratio in which the epoxy group and the carboxyl group remain. The carboxyl group-containing resin in the above (5) includes a vinyl copolymer or polyester having one or more carboxyl groups in one molecule. In the above (1) to (5), a hydroxyl group or an alkoxysilyl group may be introduced as necessary in order to enhance the curing performance of the coating film.

The reaction between the vinyl resin obtained by copolymerizing the epoxy group monomer shown in the above (5) as an essential component and the resin containing a carboxyl group is usually performed at room temperature to 150 ° C. for several days to about 2 hours. This is done by heating.

As the vinyl copolymer having a carboxyl group used in the above (5), a resin produced by the following method can also be used.

(I) Carboxyl group-containing monomers such as (meth) acrylic acid, maleic acid, itaconic acid, fumaric acid and mesaconic acid are copolymerized as essential components.

(II) After copolymerizing a hydroxyl group-containing monomer as an essential component, the anhydride of the above-mentioned polybasic acid is added by a half esterification reaction.

(III) A carboxyl group-containing monomer obtained by previously adding a hydroxyl group-containing monomer and an acid anhydride by a half esterification reaction is copolymerized as an essential component.

(IV) After copolymerizing an acid anhydride having an unsaturated bond (maleic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, hymic anhydride, etc.) as an essential component, water or alcohol is added to the mixture. It is added by a phesterification reaction.

The polyester resin (5) having a carboxyl group as an essential component is composed of a polybasic acid and a polyhydric alcohol.
Obtained by an esterification reaction with The polybasic acid used in this reaction is a compound having a carboxyl group,
For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, heptic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, and anhydrides thereof. The polyhydric alcohol is a compound having a hydroxyl group, for example, ethylene glycol, propylene glycol, butylene glycol, hexanediol, diethylene glycol, dipropylene glycol, neopentyl. Glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane,
Pentaerythritol and the like. At this time, by making the polybasic acid excessive, a polyester resin having a carboxyl group can be produced.

The epoxy group-containing monomer is a compound having at least one epoxy group and at least one polymerizable unsaturated bond in one molecule, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate −
Allyl glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate, 2- (1,2-epoxy-4,7-methanoperhydroindene-5 (6)
-Yl) oxyethyl (meth) acrylate, 5,6-
Epoxy-4,7-methanoperhydroinden-2-yl- (meth) acrylate, 1,2-epoxy-4,7-
Methanoperhydroinden-5-yl- (meth) acrylate, 2,3-epoxycyclopentenyl (meth) acrylate, (meth) acrylate of 3,4-epoxycyclohexylmethylated polycaprolactone, and the like. Can be

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and hydroxyl group monomers. Examples include hydroxyalkyl (meth) acrylate obtained by reacting with a lactone.

Examples of the alkoxysilyl group-containing monomer include:
Compounds having one or more alkoxysilyl groups and one or more polymerizable unsaturated bonds in one molecule, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxysilane) silane, γ- (meth) acryloyl Oxypropyltrimethoxysilane,
Vinyl triacetooxysilane, β- (meth) acryloyloxyethyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, 2-styrylethyltrimethoxysilane and the like can be mentioned.

Examples of other monomers include methyl (meth) acrylate and ethyl (meth) acrylate.
, Propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate
_C1-22 alkyl esters of (meth) acrylic acid, such as methacrylate and 2-ethylhexyl (meth) acrylate; methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, methoxybutyl (meth) acrylate −
_C2-18 alkoxyalkyl esters of (meth) acrylic acid, such as ethoxybutyl (meth) acrylate, ethoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate; N, N-dimethylamino Ethyl acrylate, N, N-dimethylaminoethyl acrylate, N, N-diethylaminoethyl acrylate, N
Aminoacrylic such as -t-butylaminoethyl acrylate, Nt-butylaminoethyl methacrylate, N, N-dimethylaminopropyl acrylate, N, N-dimethylaminopropyl methacrylate Monomer, acrylamide monomer such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-butylacrylamide, N-butylmethacrylamide, N-dimethylmethacrylamide And the like.

The curing composition of the present invention may contain, as a curing catalyst, onium salts, amines, halides of oxonium salts, organic zinc compounds, organic tin compounds, organic aluminum compounds, and organic boron compounds. Further, when an onium salt is used, a phosphate compound such as dibutyl phosphoric acid, which is almost equivalent to the onium salt, may be added for improving storage stability. Further, a tin compound, aluminum chelate or titanium chelate may be added as a catalyst for the condensation reaction between the hydroxyl group on the surface of the inorganic oxide colloidal dispersion and the hydroxyl group in the resin.

To the curable composition of the present invention, a vinyl copolymer or polyester resin other than the self-curable resin may be added in order to further reinforce the physical properties.

The acid value of the self-curing resin used in the present invention is preferably 30 to 110 mgKOH / g. Acid value is 30
If it is less than mgKOH / g, the curability will decrease,
If it exceeds OH / g, the compatibility with the inorganic oxide-based colloidal dispersion tends to decrease. If the epoxy content is less than 0.5, the curability tends to decrease, and if it exceeds 2.5 mmol, the storability tends to decrease.

The self-curable resin used in the present invention has a molecular weight of 1,000 to 30,000, but has a molecular weight of 1,000.
If it is less than 30, the curability tends to decrease, and if it exceeds 30,000, the storability tends to decrease. In addition, if the acid / epoxy equivalent ratio is less than 0.7 and more than 1.3, the curability decreases.

The compatibility parameter (sp value) of the self-curable resin used in the present invention is preferably from 9.0 to 11.0, and more preferably from 9.2 to 10.8. sp
When the value exceeds the upper limit or the lower limit of this range, the compatibility with the colloid is reduced. Therefore, it is preferable to set the compatibility parameter to an appropriate value within the above range according to the colloid. As the inorganic oxide-based colloidal dispersion used in the curable composition of the present invention, silica, alumina, titania, a colloidal dispersion of an inorganic oxide such as zirconia, or a silane compound represented by the following formula and reacted with these Colloidal dispersions.

R _1m R _2n Si (OR ₃ ) _4-nm, where n = 0 or 1, m = 0 or 1 (R ₁ is alkyl, alkenyl, epoxyalkyl, aminoalkyl, (meth) ) Represents an acryloyloxyalkyl or ureidoalkyl group, where m is 0
Or 1. R ₂ represents a methyl or phenyl group. n
Is 0 or 1. R ₃ is methoxy, ethoxy, 2-
Represents methoxyethoxy, 2-butoxyethoxy, and acetyl groups. The amount of the silane compound to be reacted is preferably 30 parts or less based on 100 parts of the solid content of colloidal silica.
If the amount of the silane compound exceeds 30 parts, the stain resistance tends to decrease.

Examples of the organic solvent that can be used for dispersion include methanol, isopropanol, and ethylene glycol.
Alcohol solvents such as ethylene glycol, ethylene glycol mono-n-propyl ether, hydrocarbon solvents such as hexane, heptane, xylene, toluene, cyclohexane and naphtha, methyl isobutyl ketone, methyl ethyl ketone, isophorone and acetophenone. Ketone solvents,
Amide solvents such as dimethylacetamide and methylpyrrolidone; and ester solvents such as methyl acetate, ethyl acetate, isobutyl acetate, octyl acetate, ethylene glycol monomethyl ether, and diethylene glycol monomethyl ether acetate, and these are used alone as dispersion media. Or a dispersion medium in combination. Commercially available silica colloid dispersions include, for example, methanol silica sol, MA-ST-M, IPA-ST, and EG.
-ST, EG-ST-ZL, NPC-ST, DM
AC-ST, MEK-ST, XBA-ST, MI
BK-ST (all manufactured by Nissan Chemical Industries, Ltd., trade name).

In the curable composition of the present invention, the amount of the inorganic oxide-based colloidal dispersion is 0.5 to 200 parts by weight per 100 parts by weight of the self-curing resin in terms of solid content.
If it is less than 0.5 part by weight, the scratch resistance is poorly expressed, and
If it exceeds 0 parts by weight, the weather resistance tends to decrease.

The curable composition of the present invention can be adjusted by containing the self-curable resin described above and an inorganic oxide colloidal dispersion having a specific particle size. An accelerating catalyst, an antisettling agent, an anti-flow agent, an ultraviolet stabilizer, a flame retardant, an antifouling agent, and the like can be added.

As the coloring pigment, for example, titanium oxide,
Inorganic pigments such as zinc white, carbon black, cadmium red, molybdenum red, chrome ero, chromium oxide, prussian bull, and cobalt bull, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, sulene pigments, and perylene pigments And pigments for metallic or interference patterns, such as solid color pigments such as organic pigments, scale-like aluminum, mica, mica coated with a metal oxide, and mica-like iron oxide. The amount of these color pigments is preferably in the range of 0 to 150 parts by weight per 100 parts by weight of the self-curing resin composition.

The curable composition of the present invention comprises a clear paint for forming a transparent coating film, a solid paint containing a solid color pigment, a metallic paint containing a metallic pigment, and an interference pattern pigment. It can be used as a blended interference pattern paint.

Specific examples of the coating method when the curable composition of the present invention is used for forming an overcoat film on the outer panel of an automobile are as follows.

Coating method A: Finishing with a single top coat of solid color paint with the curable composition of the present invention.

Coating method B: In forming at least one kind of colored paint and at least one kind of clear paint in order to form a multi-layer top coat, the present invention is used as the uppermost clear paint using the present invention. Form a coating.

As a specific example of this coating method B, for example,
(B-1) In a two-coat finish in which a colored paint and a clear paint are sequentially applied, the curable composition of the present invention is used as the clear paint. (B-2) The curable composition of the present invention is used as the second clear paint in a three-coat finish in which a colored paint, a first clear paint, and a second clear paint are sequentially applied. (B-3) In a three-coat finish in which the first colored paint, the second colored paint, and the clear paint are sequentially applied, a method using the curable composition of the present invention as the clear paint is exemplified.

In the above coating method, a solid color paint, a metallic paint or an interference pattern paint can be used as the colored paint.

The coating method A is, for example, applied directly to a metal or plastic substrate such as an automobile, or after applying and curing an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate coat, and then applying a viscosity. 10-25 seconds (for
Cup # 4/20 ° C.) and the solid color content of the curable composition of the present invention adjusted to a solid content of 20 to 60% by weight is coated by a method such as airless spraying, air spraying or electrostatic coating. Is a cured coating film of about 20 to 80 μm
And leave it at room temperature for a few minutes.
100 to 180 ° C, preferably about 120 to 160 ° C for about 1
It can be carried out by heating for 0 to 40 minutes for crosslinking and curing.

In the coating method (B-1), for example, an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate coat are applied and cured on a metal or plastic substrate for automobiles. After that, the colored paint is applied by airless spray, air spray, electrostatic coating, etc. so that the film thickness becomes about 10 to 50 μm with a cured coating film, and it is heated at a temperature of about 100 to 180 ° C. to crosslink and cure. The present invention which is adjusted to a viscosity of 10 to 25 seconds (Ford cup # 4/20 ° C.) and a solid content of 20 to 60% by weight after being allowed to stand or left at room temperature for several minutes without curing. A clear coating of the curable composition is applied by a similar method so that the cured coating film has a thickness of about 20 to 70 μm.
0-180 ° C, preferably about 120-160 ° C for about 10
2 to 40 minutes consisting of crosslinking and curing by heating for up to 40 minutes
It can be performed by a one-bake method (2C1B) or a two-coat two-bake method (2C2B).

The color paints used in the coating method (B-1) include solid color paints, metallic paints and light interference pattern paints, and are known per se containing resin components, color pigments and solvents. Curable paints can be used. Specifically, the resin component is at least one selected from an acrylic resin having a crosslinkable functional group (for example, a hydroxyl group, an epoxy group, a carboxyl group, an alkoxysilane group, etc.), a vinyl resin, a polyester resin, an alkyd resin, and a urethane resin. Kinds of base resins, and an alkyl etherified melamine resin for crosslinking and curing them,
A substrate comprising at least one crosslinking agent component selected from a urea resin, a guanamine resin, a polyisocyanate compound which may be blocked, an epoxy compound, a carboxyl group-containing compound, etc., based on the total weight of both components; Those containing 50 to 90% of a resin and 50 to 10% of a crosslinking agent component are preferred. The color pigments include solid color pigments, metallic pigments and light interference pattern pigments, and these can be used alone or in combination of two or more. As a solvent, an organic solvent is suitable, but an aqueous solvent may be used.

As the color paint used in the coating method (B-2), the color paint described in the above-mentioned coating method (B-1) can be used. A paint obtained by removing most or all of the coloring pigment from the above-mentioned coloring paint, or the cured product of the present invention can be used. The paint of the present invention is used as the second clear paint. In the coating method (B-2), specifically, a metal or plastic object for automobile is directly applied, or an undercoat such as a cationic electrodeposition paint and, if necessary, an intermediate coat are applied and cured. From, the above-mentioned coloring paint is applied by a method such as airless spray, air spray-electrostatic coating so that the film thickness becomes about 10 to 50 μm with a cured coating film, and is heated at about 100 to 180 ° C. to be crosslinked and cured. Or after being left at room temperature for several minutes without curing, the first clear paint is applied to the coated surface by a similar method so that the film thickness becomes about 10 to 50 μm with a cured coating film, and about 100 to 50 μm. After heating at 180 ° C. for cross-linking and curing, or after leaving it at room temperature for several minutes without curing, the viscosity is 10 to 25 seconds (Ford cup # 4/20 ° C.), and the solid content is 20 to 60% by weight. % According to the present invention The curable composition (second clear coating) is applied by a similar method so that the film thickness of the cured coating film is about 10 to 50 μm.
About 10 to 180 ° C, preferably 120 to 160 ° C.
3 to 4 minutes consisting of crosslinking and curing by heating for up to 40 minutes
It can be performed by a one-bake system (3C1B), a three-coat two-bake system (3C2B) or a three-coat three-bake system (3C3B).

As the first colored paint used in the coating method (B-3), the colored paint described in the above-mentioned coating method (B-1) can be used. Is preferred. In addition, as the second colored paint, among the colored paints of the above-mentioned coating method (B-1), a colored transparent coating film having a weak concealing property enough to allow the substrate (that is, the first colored paint coated surface) to be seen through. The paint that forms can be used and has a viscosity of 10 to 2 as the second clear paint.
5 seconds (Ford cup # 4/20 ° C), solid content 2
The paint of the present invention adjusted to 0 to 60% by weight is used.
In the coating method (B-3), specifically, a metal or plastic object to be coated for automobiles is applied directly, or an undercoat paint such as a cationic electrodeposition paint and, if necessary, an intermediate paint are applied and cured. After that, the first colored paint is applied by a method such as airless spray, air spray, and electrostatic coating so that the film thickness becomes about 10 to 50 μm as a cured coating film,
After heating at about 100 to 180 ° C. for cross-linking and curing, or leaving it at room temperature for several minutes without curing, a second colored paint is applied to the painted surface in a similar manner to form a cured coating film. Paint to 10-50μm, about 100-18
After heating at 0 ° C. for cross-linking and curing, or after leaving it at room temperature for several minutes without curing, the curable composition of the present invention, which is a clear coating material, is cured to a film thickness of about 10 by the same method. Paint to about 50μm, about 100-180
C., preferably about 120 to 160.degree. C. for about 10 to 40 minutes for crosslinking and curing, a three-coat one-bake system (3C1B) and a three-coat two-bake system (3C2B).
Alternatively, it can be performed by a three-coat three-bake method (3C3B).

[0051]

The curable composition of the present invention contains a self-curable resin containing a carboxyl group and an epoxy group in one molecule and a colloidal dispersion of fine particles of an inorganic oxide, so that even after storage, the curable composition can be reduced. Acid resistant, without causing whitening
A coating film having good scratch resistance and high coating film hardness can be obtained.

[0052]

The present invention will be described more specifically below with reference to examples and comparative examples. The parts and percentages are based on weight.

<< Carboxyl Group-Containing Resin >> Resin A: 28 parts of Swazol 1000 (hydrocarbon solvent; trade name of Cosmo Oil Co., Ltd.) in a 5-liter glass flask equipped with a stirrer, thermometer and cooling tube. Methoxypropyl acetate (12 parts) was added and heated to 130 ° C. 30 parts of methoxypropyl acetate, 32 parts of cyclohexyl methacrylate, 20 parts of maleic anhydride
Parts, styrene 5 parts, isobutyl methacrylate 34 parts,
A mixture of 9 parts of lauryl methacrylate, 9 parts of p-tert-butylperoxy-2-ethylhexanoate, and 30 parts of Swazol 1000 (the above-mentioned hydrocarbon-based solvent) was mixed with 4 parts.
The polymerization was carried out dropwise over time. This is followed by methanol 24
And 0.2 parts of triethylamine were added, and the mixture was refluxed for 7 hours, and most of the acid anhydride groups were half-esterified. Thereafter, the solvent was removed under reduced pressure to obtain a resin having a solid content of about 52%.
(Number average molecular weight about 5000, acid value 110 mg KOH /
g, compatible parameter value: 9.8) Resin B: methoxypropyl acetate 71 in a 5-liter glass flask equipped with a stirrer, thermometer and cooling tube
To 155 parts of hexahydrophthalic anhydride, p-ter
t-butyl catechol O.I. Five parts were added, and the mixture was heated and dissolved at 110 ° C. To this, 130 parts of 2-hydroxyethyl methacrylate was added dropwise over 8 hours to react, and a solution containing about 80% of a methacryloyl group-containing carboxylic acid (A) was obtained.
I got In a separate flask, 48 parts of Swazol 1000 (the above-mentioned hydrocarbon solvent), methoxypropyl acetate 1
6 parts were added and heated to 130 ° C. Solution (A) 8
0 parts, styrene 16 parts, isobutyl acrylate 20
Parts, p-tert-butyl peroxyhexaate 10
And a mixture of 20 parts of methoxypropyl acetate were added dropwise over 4 hours to polymerize to obtain a resin. (Number average molecular weight: about 5,000, acid value: 118 mg KOH / g, compatibility parameter: 9.7, solid content: about 51%) Resin C: hexahydroanhydride in a 5-liter glass flask equipped with a stirrer, thermometer, and cooling tube Phthalic acid 131
, 42 parts of neopentyl glycol, 82 parts of trimethylolpropane, and 16 parts of xylene, the temperature was raised to 230 ° C, and water was distilled out of the system. Then, after cooling to 120 ° C., 128 parts of hexahydrophthalic anhydride was added to cause a reaction, followed by cooling. This was diluted with xylene to obtain a resin monomer having a solid content of about 50%, an acid value of 120, a number average molecular weight of about 2500, and a compatible parameter of 9.9.

<< Epoxy Group-Containing Resin >> Resin D: Into a 5 liter glass flask equipped with a stirrer, a thermometer and a condenser, 48 parts of swazol (the above-mentioned hydrocarbon-based solvent) and 7 parts of butanol are placed. , Heated to 130 ° C. 20 parts of styrene, 30 parts of glycidyl methacrylate, 17 parts of lauryl methacrylate, 9 parts of isobutyl methacrylate, 24 parts of 4-hydroxybutyl acrylate, 9 parts of butanol, 2, 2 A mixture of 9 parts of '-azobis (2-methylbutyronitrile) was added dropwise over 4 hours and polymerized to obtain a resin having a solid content of about 60%. (Number average molecular weight about 6000, epoxy group content 2.0 mmol /
g, hydroxyl value 89 mg KOH / g, compatible parameter 9.7) << Synthesis example of self-curable resin >> Self-curable resin: Resin A and resin D are mixed at a ratio of 1/1 by solid content, Was measured for acid value. (Initial acid value: 55m
(gKOH / g) Thereafter, the system was reacted at 100 ° C. for 2 hours, and then immediately cooled to room temperature to obtain a self-curing resin. (Number average molecular weight about 10,000, acid value 47 mgK
OH / g) Self-curing resin: The resin B was used in place of the resin A, reacted at 100 ° C. for 2 hours, and cooled to obtain a self-curing resin. (Number average molecular weight about 11000, acid value 50m
gKOH / g) Self-curing resin: The resin C was used in place of the resin B in the above, reacted at 100 ° C. for 2 hours, and then cooled to obtain a self-curing resin. (Number average molecular weight about 8000, acid value 5
1 mg KOH / g) << Blending of paint >> XB as inorganic oxide colloidal dispersion
A-ST (manufactured by Nissan Chemical Co .; average particle size 10 to 20 nm),
An organic solvent-dispersed colloidal silica having a solid content of 30% was used.

Example 1: 180 parts of a self-curing resin (about 100 parts of solid content) was added to 133 parts of XBA-ST (solid content of 40 parts).
Parts).

Example 2 A self-curing resin was used in place of the self-curing resin of Example 1.

Example 3 A self-curing resin was used in place of the self-curing resin of Example 2.

Comparative Example 1: 83 parts of resin A (solid content: about 50
Parts), 97 parts of resin D (about 50 parts of solid content), XBA-ST
133 parts (solids content 40 parts) were mixed.

Comparative Example 2: Resin A of Comparative Example 1 was replaced with Resin B.

Comparative Example 3: Resin A of Comparative Example 1 was replaced with Resin C.

Comparative Example 4: 83 parts of resin A (solid content: about 50
Parts) and 97 parts of Resin D (about 50 parts of solid content).

Comparative Example 5: Resin A of Comparative Example 4 was replaced with Resin B.

Comparative Example 6: Resin A of Comparative Example 4 was replaced with Resin C.

To each of Examples 1 to 3 and Comparative Examples 1 to 6, 0.5 part of tetrabutylammonium bromide and 0.5 part of dibutylphosphoric acid were added as curing accelerators to prepare coating materials.

Film Properties Acrylic resin / melamine resin organic solvent type metallic paint (hardened film thickness: 20 μm) was applied to a metal plate which was coated with a cationic electrodeposition paint and an intermediate paint, and was cured by heating.
After standing for a minute, the organic solvent-based thermosetting coating composition (clear coating) prepared in Examples and Comparative Examples was applied to the uncured coated surface so as to have a cured film thickness of 40 μm.
For 30 minutes to simultaneously cure both coating films. (2 coats 1 bake system) Table 1 shows the performance test results of the obtained cured coating films.

In Table 1, the paint state : Initially and after 10 days at room temperature, the paint was placed in a test tube, allowed to stand, and the color was visually observed.

Film state : Initially and after 10 days at room temperature, the paint was applied under the above conditions and evaluated by visual observation.
Indicates that the gloss and smoothness are good, Δ indicates that the gloss and smoothness are considerably poor, and X indicates that the gloss and smoothness are extremely poor.

Acid resistance of coating film : After 10 days at room temperature, the coating material was applied under the above conditions, and the test coated plate was halved in a 40% sulfuric acid aqueous solution.
After being immersed and left at 50 ° C. for 5 hours, it was washed with water and the coated surface was visually observed. ○ indicates no abnormality at all, △ indicates a slight step difference at the boundary between the immersed part and the non-immersed part, and X indicates significant stains, whitening and blistering.

Scratch resistance : The paint after 10 days at room temperature was painted under the above conditions, and the automobile having the test plate applied to the roof was washed 10 times with a car washer to visually observe the state of the painted surface. did. As a car washer, "PO20FWRC" manufactured by Yasui Sangyo was used. ○ indicates no change compared to the initial gloss, ツ indicates glossy compared to the initial gloss, and X indicates more glossy compared to the initial gloss.

Tucon hardness (20 ° C.) : A paint after 10 days at room temperature is applied under the above conditions, and the paint is applied on a glass plate with a cured coating to a thickness of 30 μm, and is cured by heating at 140 ° C. for 30 minutes. The coated film was placed at 20 ° C. at America
n TUKON microhardness test by Chain & Cablc Company
The value measured at r.

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[Table 1]

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──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat 参考 (Reference) C09D 7/12 C09D 7/12 Z (72) Inventor Kazuhiro Kato 17 Higashi-Yawata 4-machi, 17 Hiratsuka-shi, Kanagawa Prefecture No.1 Kansai Paint Co., Ltd. F-term (reference) 4D075 AE02 CA02 CA44 DB02 DC12 EA12 EA19 EA43 EB33 EB54 4J036 AK11 FA05 GA01 GA08 GA09 GA10 GA11 GA15 JA01 4J038 CG011 CG031 CG061 CG071 CG01 MA171 GA371 NA04 NA11 PA07 PB07

Claims (6)

[Claims] 1. A curable composition comprising a self-curing resin containing a carboxyl group and an epoxy group in one molecule and an inorganic oxide-based colloidal dispersion. 2. The self-curable resin having an acid value of 30 to 11.
The curable composition according to claim 1, wherein the curable composition has 0 mgKOH / g, an epoxy content of 0.5 to 2.5 mmol / g, and a number average molecular weight of 1,000 to 30,000. 3. The curable composition according to claim 1, wherein the self-curable resin has an acid / epoxy equivalent ratio of 0.7 to 1.3. 4. Compatible parameters of self-curing resin
The curable composition according to claim 1, wherein the value is 9.0 to 11.0. 5. The method according to claim 1, wherein at least one kind of colored paint and at least one kind of clear paint are sequentially applied to the object to form a multi-layer top coat, and the uppermost clear paint is used. A method for forming a multi-layer overcoat film, characterized by using the organic solvent-based thermosetting coating composition according to any one of the above. 6. The coating method according to claim 5, wherein the object to be coated is an automobile body.