JPH04226181A - Thermosetting coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to new and useful thermosetting coating compositions, particularly for automotive topcoats. More specifically, each uses a hydroxyl group-containing resin and a carboxyl group-containing resin as essential base resin components,
On the other hand, top clear paints containing an epoxy group-containing compound and an amino resin as essential curing agent components, especially those using a two-coat one-bake method or a three-coat two-bake method, as well as one-coat one-bake paints containing pigments. The present invention relates to a thermosetting resin composition for coating, which is suitable as a solid color paint for automobiles, and is particularly useful as a top coating for automobiles.

0002

[Prior Art] Up until now, acrylic resin/melamine resin (acrylic melamine) type top clear paints have generally been used, and alkyd resin/melamine resin (acrylic melamine) type paints have been used as solid color paints.
Alkyd melamine) type products have been used.

[0003] So-called melamine resin curing agent paints such as acrylic melamine paints and alkyd melamine paints are
The coating film has excellent physical properties such as gloss, weather resistance, and scratch resistance, so it is widely used as a top clear paint for automobiles.

[0004] However, in recent years, acid rain has become more important, and problems such as the tendency to cause stains have come into focus. This is due to the fact that melamine resin, which is weak against acids, is used as a curing agent component.

[0005] Although studies are being carried out at a rapid pace on curing agent components to replace melamine resins, a new unresolved problem has been encountered in that only resin compositions with insufficient scratch resistance can be obtained. The reality is that there are.

[0006]

[Problems to be Solved by the Invention] As described above, as long as the prior art as described above is followed, it is possible to create a resin composition for coating, for example, for automobile topcoating, which can simultaneously satisfy acid resistance and scratch resistance. The reality is that it is extremely difficult to obtain.

[0007] To this end, the present inventors have developed an extremely versatile and practical product that can maintain properties such as gloss and weather resistance while also ensuring unique properties such as acid resistance and scratch resistance. In search of paint compositions for automobile topcoats, etc.
I started research.

[0008] Therefore, the problem to be solved by the present invention is to provide a novel thermosetting method that maintains properties such as gloss and weather resistance while also exhibiting excellent properties such as acid resistance and scratch resistance. An object of the present invention is to provide a coating composition with a high quality.

[0009]

[Means for Solving the Problems] Therefore, the present inventors focused on the problems to be solved by the invention as described above, and as a result of intensive studies, the inventors found that A composition comprising a resin and a resin having a specific polar functional group called a carboxyl group as essential base resin components, and an epoxy group-containing compound and an amino resin as essential curing agent components has high gloss and weather resistance. The present invention was completed based on the discovery that it is extremely valuable, not only in terms of properties, but also in acid resistance and scratch resistance.

That is, the present invention provides a thermosetting coating composition comprising a hydroxyl group-containing resin and a carboxyl group-containing resin, and an epoxy group-containing compound and an amino resin, respectively, as essential components. In particular, the composition of the present invention is particularly suitable for top clear applications such as the so-called 2-coat 1-bake system or 3-coat 2-bake system, and for 1-coat 1-bake solid color applications. It is.

[0011] That is, the present invention first coats a crosslinkable base coat paint containing a brightening agent and/or a color pigment on an object to be coated (substrate), and then heat-cures the base coat coated surface. A so-called 2-coat, 1-bake coating method in which a thermosetting clear coat paint (clear paint) is applied and cross-linked, or a thermosetting clear coat paint (clear paint) is applied on top of the thus obtained laminated coating. ) for each top clear coating in various laminated coating methods such as the so-called 3-coat, 2-bake coating method, in which 1 coat 1 containing colored pigments is applied to the object to be coated. An extremely useful thermosetting coating composition with excellent and well-balanced properties such as gloss, weather resistance, acid resistance, and scratch resistance, suitable for use in baked solid colors. It tries to provide something.

[0012] By the various coating methods mentioned above,
For example, when painting the body of a car, it is almost never the case that base coat paint or clear coat paint is applied directly to the object to be painted, and usually the film formation process of the object is rarely applied. , electrodeposition coating and/or intermediate coating, but it goes without saying that the conventional method up to this point can be applied as is.

[0013] Next, a two-coat one-bake method or a three-coat method or three
As a base coat paint for various laminated coatings such as a coat-2-bake method, a paint using a commonly used acrylic resin and an amino resin as a crosslinking agent, especially a melamine resin is used.

[0014] In some cases, polyester resins can also be used, and furthermore, these base resin components include
It is also possible to combine cellulose derivatives. Moreover, as a crosslinking agent, of course, isocyanate resin (isocyanate prepolymer) can also be used.

[0015] Furthermore, as a base coat paint, of course, one containing a brightening agent or a coloring pigment is used, but among these, only the most representative brightening agents will be exemplified. In particular, metal powder such as aluminum powder, mica, or titanium oxide coated mica may be used.

[0016]Next, to exemplify only particularly representative color pigments, various inorganic pigments such as titanium oxide or carbon black, various organic pigments such as phthalocyanine blue, phthalocyanine green, or quinacridone red, etc. It is.

Furthermore, as the two-coat, one-bake clear paint in the three-coat, two-bake coating, a thermosetting paint such as a normal acrylic resin or melamine resin is generally used. In such a 3-coat, 2-bake coating, it is effective for the color coating composition to be used as a subsequent 3-coat, 2-bake clear, that is, as a top clear.

It goes without saying that the various colored pigments mentioned above can be used as the solid color paint in the one-coat, one-bake coating. put it here,
Examples of the above-mentioned hydroxyl group-containing resin, which is one of the essential components constituting the thermosetting coating composition of the present invention, include resins typified by hydroxyl group-containing vinyl copolymer resins, among others. , (meth)acryloyloxy group-containing hydroxyl group-containing resin (hereinafter also referred to as hydroxyl group-containing acrylic resin), and the like.

[0019] To exemplify only particularly representative hydroxyl group-containing vinyl copolymer resins, the hydroxyl group-containing α,β-ethylenically unsaturated monomers (hereinafter referred to as hydroxyl group-containing vinyl monomer) and other copolymerizable monomers.

[0020] Among them, only representative examples of hydroxyl group-containing vinyl monomers are listed, such as 2-hydroxyethyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate.
Hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxy Propyl (meth)acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl-monobutyl fumarate, polypropylene glycol, or polyethylene glycol mono(meth)acrylate, "Plaxel FM, FA Monomer" [Daicel These include hydroxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids such as Caprolactone Addition Monomer (manufactured by Kagaku Co., Ltd.), or adducts of these with ε-caprolactone.

Next, to exemplify only particularly representative monomers that can be copolymerized, (meth)
Carboxyl group-containing monomers such as acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, mono-n-butyl maleate, diethyl fumarate or diethyl itaconate; styrene, α-methylstyrene, p-te
Aromatic vinyl monomers such as rt-butylstyrene or vinyltoluene;

Methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-
(meth)acrylates such as ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl acrylate, benzyl (meth)acrylate, dibromopropyl (meth)acrylate or alkoxyalkyl (meth)acrylate;

[0023]N-
Dimethylaminoethyl (meth)acrylamide, N-diethylaminoethyl (meth)acrylamide, N-dimethylaminopropyl (meth)acrylamide or N
-Amino group-containing amide monomers such as diethylaminopropyl (meth)acrylamide; dialkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate or diethylaminoethyl (meth)acrylate; tert-butylaminoethyl (meth)acrylate; meth)acrylate, tert-butylaminopropyl (meth)acrylate, tert-butylaminobutyl (meth)acrylate, aziridinylethyl (meth)acrylate, pyrrolidinylethyl (meth)acrylate or piperidinylethyl (meth)acrylate Basic nitrogen atom-containing monomers such as;

General formula

[0025]

[Chemical formula 1]

[However, R1 in the formula is -H or -C
H3, R2 and R3 each represent -H or a C1-C8 alkyl group, an aryl group, or a C7-C12 aralkyl group, and A represents a C1-C14 aralkyl group, which may be the same or different. It represents an alkylene group. ] Dialkyl ((meth)acryloyloxyalkyl) phosphates or (meth)acryloyloxyalkyl acid phosphates;

General formula

[0028]

[Case 2]

[R1, R2 and R3 and A
is as mentioned above. ] dialkyl [
(meth)acryloyloxyalkyl] phosphites; (meth)acryloyloxyalkyl acid phosphites;

Furthermore, alkylene oxide adducts of the above (meth)acryloyloxyalkyl acid phosphates or acid phosphites, glycidyl (
Esterified products of epoxy group-containing vinyl monomers such as meth)acrylate and methylglycidyl (meth)acrylate with phosphoric acid or phosphorous acid, or acidic esters thereof, 3-chloro-2-acid phosphoxypropyl Phosphorous atom-containing monomers such as (meth)acrylate;

2-Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3
-Hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, di- α,β-unsaturated carboxylic acid hydroalkyl esters such as 2-hydroxyethyl fumarate, mono-2-hydroxyethyl-monobutyl fumarate or polyethylene glycol mono(meth)acrylate, maleic acid, succinic acid, phthalic acid ,
With anhydrides of polycarboxylic acids such as hexahydrophthalic acid, tetrahydrophthalic acid, benzenetricarboxylic acid, benzenetetracarboxylic acid, "Himic acid" (a product of Hitachi Chemical Co., Ltd.), tetrachlorophthalic acid or dodecynylsuccinic acid. Adduct, vinylethoxysilane, α-
Silicon monomers such as methacryloxypropyltrimethoxysilane;

Glycidyl (meth)acrylate, (β-
Epoxy group-containing monomers such as methyl)glycidyl (meth)acrylate and (meth)allyl glycidyl ether; acid anhydride group-containing monomers such as vinyl esters of maleic anhydride, itaconic anhydride, and trimellitic anhydride Diesters of unsaturated dicarboxylic acids such as fumaric acid or itaconic acid and monohydric alcohols; Vinyl acetate, vinyl benzoate, "Beoba" (vinyl ester manufactured by Shell)
Vinyl esters such as;

"Viscoat 88F, 8FM, 17FM,
3F or 3FM" [fluorine-containing acrylic monomer manufactured by Osaka Organic Chemical Industry Co., Ltd.], perfluorocyclohexyl (meth)acrylate, di-perfluorocyclohexyl fumarate or N-iso-propyl perfluorooctanesulfonamidoethyl (meth) Vinyl esters containing (per)fluoroalkyl groups such as acrylates,
Fluorine-containing polymerizable compounds such as vinyl ethers, (meth)acrylates, or unsaturated polycarboxylic acid esters; or free from polar functional groups such as various olefins such as (meth)acrylonitrile, vinyl chloride, or vinylidene chloride. vinyl monomers, etc.

Furthermore, if necessary, as a copolymerizable unsaturated bond-containing resin, an unsaturated bond-containing resin modified with oil or fatty acid that is copolymerizable with the various monomers listed above may be used. So-called alkyd resins, unsaturated bond-containing polyester resins, or unsaturated bond-containing vinyl resins can also be added to the copolymerizable monomers in the form of so-called macromonomers.

The hydroxyl group-containing vinyl copolymer resin may be prepared by a conventional method, for example, by radical copolymerization using a polymerization initiator such as a peroxide or an azo compound in an organic solvent.

Next, as the carboxyl group-containing resin, which is one of the essential components constituting the thermosetting coating composition of the present invention, examples include carboxyl group-containing vinyl copolymer resins. Examples of resins include (meth)acryloyloxy group-containing carboxyl group-containing resins (hereinafter also referred to as carboxyl group-containing vinyl copolymer resins).

[0037] To exemplify only particularly typical examples of the carboxyl group-containing vinyl copolymer resin, the carboxyl group-containing monomers listed above are essential components, and furthermore, the carboxyl group-containing monomers listed above are included as essential components. These include those obtained using various other copolymerizable monomers, hydroxyl group-containing vinyl monomers, and the like.

The acid value of the carboxyl group-containing vinyl copolymer resin is 30 to 150, preferably 50 to 150.
A range of 120 is appropriate. If it is less than 30,
It becomes difficult to obtain a coating film with excellent acid resistance and scratch resistance, and on the other hand, if it exceeds 150, the viscosity of the coating tends to increase significantly, and workability deteriorates. Either case is not preferable.

On the other hand, as the acid component used in preparing the hydroxyl group-containing or carboxyl group-containing polyester resin, in consideration of the weather resistance of the coating film, particularly representative so-called alicyclic carboxylic acids having a cyclohexane ring are used. To exemplify only 1,1-cyclohexanedicarboxylic acid, hexahydro(anhydride)carboxylic acid, 1,1-cyclohexanedicarboxylic acid,
, 3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid or methylcyclohexahydro (
(anhydrous) phthalic acid, etc., and if necessary, 4-ter
Cyclohexane mono- or polycarboxylic acids such as t-butylcyclohexane monocarboxylic acid, hexahydrobenzoic acid or hydrogenated trimellitic acid, as well as their methyl esters can also be used.

Other acid components include (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, tert-butylbenzoic acid or p-methylbenzoic acid, or (anhydrous)
Various aromatic carboxylic acids such as trimellitic acid are used, and furthermore, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, tetrachlorophthalic acid, het's acid, Himic acid (anhydride), maleic acid (anhydride),
Fumaric acid or itaconic acid may also be used.

[0041] Typical examples of polyhydric alcohol components used together with the acid components mentioned above include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol A, glycerin, trimethylolethane, trimethylolpropane,
Such as pentaerythritol, dipentaerythritol or sorbitol.

[0042] An oil component can also be used as part of the acid component in preparing a hydroxyl group-containing or carboxyl group-containing polyester resin within a range where the oil length is less than 30%, but weather resistance etc. From the viewpoint of
It is preferable to use octenoic acid or isononanoic acid.
Furthermore, if necessary, rice bran oil fatty acid, tall oil fatty acid, soybean oil, castor oil, or dehydrated castor oil can also be used as appropriate.

[0043] The hydroxyl value of the hydroxyl group-containing vinyl copolymer resin or hydroxyl group-containing polyester resin obtained in this way is preferably within the range of 50 to 200 mgKOH/g, preferably 80 to 150 mgKOH/g, On the other hand, the acid value of the carboxyl group-containing polyester resin is suitably in the range of 30 to 150 mgKOH/g, preferably 50 to 120 mgKOH/g.

If it is less than 50 KOH/g (hereinafter, this unit is omitted), it becomes difficult to obtain a coating film with good scratch resistance (scratch resistance) as a composite curing system. On the other hand, if it exceeds 200, the viscosity of the paint tends to become high, which in turn leads to poor workability, and in addition, the appearance of the paint film is impaired. Undesirable.

[0045] The blending ratio of the hydroxyl group-containing resin and carboxyl group-containing resin is as follows:
Solid content weight ratio: carboxyl group-containing resin/hydroxyl group-containing resin = 50/100 to 200/100, preferably 8
A range of 0/100 to 150/100 is appropriate.

On the other hand, the above-mentioned epoxy group-containing compound, which is one of the essential components of the thermosetting coating composition of the present invention, is a compound containing substantially two or more epoxy groups (glycidyl groups) in one molecule. ), so of course any compound can be used as long as it follows this definition, but especially compounds that have both an epoxy group and a hydrolyzable silyl group in one molecule, Alternatively, it is desirable to use a compound having both an epoxy group and a hydroxyl group in one molecule, or a compound having both an epoxy group, a hydrolyzable silyl group, and a hydroxyl group in one molecule.

As the epoxy group-containing compound, first,
Examples of compounds having at least two epoxy groups in one molecule include ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether. or polyglycidyl ethers of polyhydric alcohols such as triglycidyl ether of glycerin;

Polyglycidyl esters of polyhydric carboxylic acids such as diglycidyl ester of phthalic acid, diglycidyl ester of isophthalic acid or diglycidyl ester of adipic acid; or diglycidyl ether type epoxy resin of bisphenol A or bisphenol F;
Examples include polyepoxy compounds such as various epoxy resins such as novolac type epoxy resins and hydantoin ring-containing epoxy resins, and further, glycidyl ester ethers of p-oxybenzoic acid, and various alicyclic compounds as described below. Also included are compounds containing formula epoxy groups.

That is, the structural formula group

[0050]

[Chemical formula 3]

Next, as the epoxy resin, epoxy group-containing vinyl monomers having an epoxy group in the side chain,
The use of copolymerized resins with other copolymerizable monomers is desirable, particularly in terms of coating film properties such as scratch resistance.

[0052] To exemplify only particularly representative epoxy group-containing vinyl monomers, the general formula group

[0053]

[C4]

[However, R1 in each formula is -H or -
CH3 represents a divalent aliphatic hydrocarbon group having 1 to 6 carbon atoms, and R5 represents a divalent hydrocarbon group having 1 to 10 carbon atoms. ] Alicyclic epoxy group-containing vinyl monomers, or general formula

00
55]

[C5]

[However, R1 and R4 in the formula are as described above. ] and so-called aliphatic epoxy group-containing vinyl monomers.

Here, the divalent aliphatic saturated hydrocarbon group (R4) having 1 to 6 carbon atoms is a linear or branched alkylene group, such as methylene, ethylene, propylene, tetramethylene, Examples of the divalent hydrocarbon group (R5) having 1 to 10 carbon atoms include ethyl ethylene, pentamethylene, and hexamethylene groups. Mention may be made of methylene, ethylethylene, pentamethylene, hexamethylene, polymethylene, phenylene, cyclohexylene or xylylene.

Other monomers that can be copolymerized with these various epoxy group-containing vinyl monomers are only particularly representative, excluding carboxyl group-containing vinyl monomers. Otherwise, the various monomers listed above, which are used in preparing the hydroxyl group-containing vinyl copolymer resin described above, can be applied as they are.

[0059] Next, in one molecule described above, each of
Typical compounds having both an epoxy group and a hydrolyzable silyl group include a vinyl polymer having both of these types of reactive groups and a silane coupling agent having an epoxy group.

Here, the hydrolyzable silyl group is represented by the general formula

[0061]

[C6]

[However, R6 in the formula is a hydrogen atom or a monovalent organic group such as an alkyl group, an aryl group, or an aralkyl group, and R7 is a halogen atom or an alkoxyl group, an acyloxy group, a phenoxy group, an iminooxy group, or an alkenyloxy group. , where a is 0, 1
or a natural number of 2. ] refers to a reactive group that is easily hydrolyzed, such as a halosilyl group, an alkoxysilyl group, an acyloxysilyl group, a phenoxysilyl group, an iminooxysilyl group, or an alkenyloxysilyl group.

Any known method can be applied to prepare the vinyl copolymer resin having the above-mentioned specific bireactive groups. -(meth)acryloyloxypropylmethyldimethoxysilane, γ-(meth)acryloyloxypropyltriisopropenyloxysilane, γ-(meth)acryloyloxypropyltriiminooxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyl( Vinyl monomers having a hydrolyzable silyl group such as tris-β-methoxyethoxy)silane, vinyltriacetoxysilane or vinyltrichlorosilane, and (β-methyl)glycidyl(
meth)acrylate, allyl glycidyl ether, di(
epoxy group-containing vinyl monomers such as β-methyl)glycidyl malate or di(β-methyl)glycidyl fumarate, and, if necessary, various other copolymerizable vinyl monomers such as those listed above. Solution radical copolymerization using monomers or ■γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltriisopropenyloxy In the presence of a chain transfer agent such as silane or γ-mercaptopropyltriiminooxysilane, a monomer mixture containing the above-mentioned epoxy group-containing vinyl monomers as an essential component is subjected to solution radical (co)polymerization, etc. This method is mentioned as a simple method.

Next, typical examples of the above-mentioned epoxy group-containing silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-glycidoxypropylmethyl disilane. Adducts of glycidol with ethoxysilane, γ-glycidoxypropyltriisopropenyloxysilane, γ-glycidoxypropyltriiminooxysilane, γ-isocyanatepropyltriisopropenyloxysilane or γ-isocyanatepropyltrimethoxysilane, etc. or an adduct of γ-aminopropyltrimethoxysilane or the like and a diepoxy compound.

Compounds having both an epoxy group and a hydroxyl group in one molecule are also effective for increasing the curability, and to exemplify only particularly desirable such compounds, the above-mentioned compound is effective. It is obtained by copolymerizing an epoxy group-containing vinyl monomer having an epoxy group in its side chain with a hydroxyl group-containing vinyl monomer, and if necessary, also copolymerizing other copolymerizable monomers. It's like being exposed to something.

Furthermore, as one of the epoxy group-containing vinyl copolymer resins, compounds having an epoxy group, a hydrolyzable silyl group, and a hydroxyl group in one molecule can also be used. It is obtained by copolymerizing each monomer having a functional group.

The amount of the epoxy group-containing compound to be used is based on the total solid content of the four essential components of the composition of the present invention, that is, the hydroxyl group-containing resin, the carboxyl group-containing resin, the epoxy group-containing compound, and the amino resin (hereinafter referred to as A suitable range is 10 to 40% by weight, preferably 15 to 30% by weight, based on the total amount of resin.

[0068]Next, to exemplify only particularly representative amino resins, especially melamine resins, which are one of the essential components of the thermosetting coating composition of the present invention, alkyl Etherified melamine resin, etc.

0
[069] Particularly representative examples of such alkyl etherified melamine resins include "Super Beckamine L-117-60" [product of Dainippon Ink & Chemicals Co., Ltd.] and "Yuban 225" [product of Dainippon Ink and Chemicals Co., Ltd.]. Butoxymethylmelamine resin such as Mitsui Toatsu Chemical Co., Ltd. product;

“Cymel #300 or #303” [
Mitsui Cyanamid Co., Ltd. products] or “Sumimar”
Methoxymethyl melamine resin such as "M-100" [product of Sumitomo Chemical Co., Ltd.]; or "Cymel #1"
130'' or methoxy-butoxy mixed etherified methylmelamine resin such as ``Sumimar M-66B''.

The amount of the melamine resin used is 5 to 30% by weight, preferably 1% by weight based on the total amount of resin.
A range of 0 to 25% by weight is suitable. In order to accelerate the curing of the composition of the present invention, curing catalysts can be used, but typical examples of such curing catalysts include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, Acid catalysts such as dinonylnaphthalenedisulfonic acid or amine-blocked products thereof, half esters of tetrachlorophthalic anhydride and monohydric alcohol, organic acids such as trichloroacetic acid; tetraisopropyl titanate, dibutyltin laurate,
Metal-containing compounds such as dibutyltin acetate, dibutyltin dioctate, cobalt naphthenate;

Alternatively, phosphorus acidic compounds such as monoalkyl phosphoric acid, dialkyl phosphoric acid, monoalkyl phosphorous acid, dialkyl phosphoric acid, or triphenylphosphine may be used. The appropriate amount of the curing catalyst used is within the range of 0.1 to 10% by weight (based on the total amount of resin).

The thermosetting coating composition of the present invention, which is thus obtained and is useful as a top clear coating, does not usually contain pigments, but it contains pigments to the extent that the transparency of the coating film is maintained, that is, Without departing from the purpose of the invention,
In addition, as long as the effects of the present invention are not impaired, there is no problem in incorporating the above-mentioned glittering agents and/or coloring pigments used in base coat paints.

[0074] The composition of the present invention may further contain, if necessary,
In addition to various resins and solvents, various well-known and commonly used additives are added, such as flow regulators, color separation inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, and silane coupling agents. Of course it is possible.

Typical examples of the various resins include cellulose resins such as nitrocellulose or cellulose acetate butyrate, vinyl chloride/vinyl acetate copolymer resins, ketone resins, petroleum resins, polyester resins, and , fluororesin, etc.

Examples of the solvents include hydrocarbons such as toluene, xylene, cyclohexane, n-hexane or octane; esters such as methyl acetate, ethyl acetate, butyl acetate or ethylene glycol monoethyl ether acetate; acetone and methyl ethyl ketone. , methyl isobutyl ketone, methyl amyl ketone or cyclohexanone;

Dimethylformamide, dimethylacetamide or N
- amide solvents such as methylpyrrolidone; or alcoholic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol or ethylene glycol monoalkyl ether;
Alternatively, a mixture thereof is typical.

[0078] In order to use the thus obtained thermosetting coating composition of the present invention as a top clear paint or solid color paint to form a coating film with high desired practical effects, for example, surface treatment is required. Alternatively, if necessary, apply a primer or surfacer in advance to treat the base material to be coated, and then apply each coating composition, that is, paint, to the following general coatings. Paint it with content.

That is, when used as a top clear paint, the base coat paint is first diluted with a diluting solvent as needed on the surface of the substrate to be coated as described above, and the dry film thickness is 10 to 10%. In the case of painting in the usual way so that the thickness is 50 μm, and then applying 2 coats and 1 bake painting,
The composition of the present invention can be applied to a dry film thickness of 5 to 40μ by a conventional method.
It is sufficient to apply the coating so that it becomes m, and then crosslink it under the specified conditions.Also, in the case of 3-coat, 2-bake coating,
It is coated and crosslinked in the same manner as the two-coat, one-bake coating described above, and then the composition of the present invention is coated thereon in a layered manner to a dry film thickness of 5 to 40 μm, and then Afterwards, crosslinking may be performed under predetermined conditions.

When used as a one-coat, one-bake solid color paint, the coating is similarly applied to the surface of the substrate to be coated as described above using a conventional method so that the dry film thickness is 20 to 60 μm. However, it may be crosslinked under predetermined conditions.

[0081] Normally, appropriate conditions for each of the above-mentioned crosslinking are 110 to 170°C for 15 to 40 minutes, preferably 130 to 150°C for 20 to 30 minutes. Thus, both the so-called solid color coating film and the top coat coating film (top clear coating film) obtained using the thermosetting coating composition of the present invention have particularly good acid resistance and scratch resistance. However, it has excellent gloss, leveling properties, and sharpness, and also has good painting workability.

[0082]

EXAMPLES Next, the present invention will be explained in more detail by reference examples, examples, comparative examples, applied examples, and comparative applied examples.

[0083] In the following, all parts and percentages are based on weight unless otherwise specified. Reference example
1 (Preparation example of hydroxyl group-containing vinyl copolymer resin) Stirrer,
In a four-necked flask equipped with a thermometer, condenser, and nitrogen inlet tube, 500 parts of "Solvesso 100" (a mixture of aromatic hydrocarbon solvents manufactured by Exxon, USA) and 200 parts of n-butanol were added. It was charged and kept at 120°C.

Next, 250 parts of styrene, 30 parts of
0 parts of n-butyl methacrylate, 120 parts of n-butyl acrylate, 320 parts of 2-hydroxyethyl methacrylate and 10 parts of acrylic acid, and 30 parts of tert-butylperoxy-2-ethylhexanoate;
10 parts of azobisisobutyronitrile and di-ter
10 parts of t-butyl peroxybenzoate, 200 parts of "Solvesso 100" and 10 parts of n-butanol
0 parts were added dropwise over 5 hours.

After completion of the dropwise addition, the reaction was continued by maintaining the same temperature for 6 hours to obtain a solution of the target resin with a nonvolatile content of 50.2% and a hydroxyl value of 140. Hereinafter, this will be abbreviated as resin (A-1).

Reference Example 2 (Same as above) A solution of a hydroxyl group-containing resin was obtained in the same manner as in Reference Example 1, except that the raw material charging ratios were changed as shown in Table 1. The property values are summarized in the same table.

[0087]

[Table 1]

Reference Examples 3 and 4 (Example of Preparation of Carboxyl Group-Containing Vinyl Copolymer Resin) The desired carboxyl A solution of group-containing resin was obtained. The property values for each resin solution are summarized in the same table.

[0089]

[Table 2]

Reference Example 5 (Example of Preparation of Carboxyl Group-Containing Polyester Resin) In a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser with a dehydration trap, and a nitrogen gas inlet tube, 136 parts of trimethylolpropane and neopentyl were placed. 53 parts of glycol and 208 parts of 1,6-hexane glycol were charged, and the temperature was raised to 150°C.

Next, 289 parts of hexahydrophthalic acid, 410 parts of adipic acid and 0.8 parts of lithium hydroxide were added.
5 parts of the mixture was added and the temperature was raised to 220° C., and further, a dehydration condensation reaction was carried out at this temperature, and the reaction was continued until the solid content acid value reached 70.

After the reaction is completed, it is cooled and the xylene 428
A solution of the target resin having a nonvolatile content of 70% and an acid value of solid content of 70 was obtained. Below, this resin (
It is abbreviated as P-1).

Reference Examples 6 and 7 (Same as above) A solution of the target resin was obtained in the same manner as in Reference Example 5, except that the raw material charging ratios were changed as shown in Table 3.

[0094] The respective property values are summarized in the same table.

The abbreviations in the table have the following meanings. HHPA…………hexahydrophthalic acid IPA…………
…Isophthalic acid AA………………Adipic acid TMP………Trimethylolpropane NPG……
...Neopentyl glycol 1,6-HD...1,6-
Hexanediol (1,6-hexane glycol)

[0096]

[Table 3]

Reference Examples 8 and 9 (Example of Preparation of Hydroxyl Group-Containing Polyester Resin) A solution of the desired resin was obtained in the same manner as in Reference Example 5, except that the raw material charging ratios were changed as shown in Table 4.

[0098]

[Table 4]

Reference Examples 10 to 14 (Preparation Examples of Epoxy Group-Containing Compounds) Solutions of various target compounds were prepared in the same manner as in Reference Example 1, except that the raw material charging ratios were changed as shown in Table 5. I got it. The property values for each compound solution are summarized in the same table.

[0100]

[Table 5]

Reference Example 15 (Example of Preparation of Base Coat Paint) A mixture prepared by a conventional paint preparation method according to the composition ratio shown below was mixed with a diluting solvent in a Ford cup #4 for 12 to 13 seconds. The viscosity was adjusted so that the desired paint was obtained. Hereinafter, this will be abbreviated as paint (BC-1).

0102 “Beckolite 57-1054”
Part 72 [Dainippon Ink Chemical Industry Co., Ltd.]
Made of hydroxyl group-containing polyester resin;
Volatile content = 70%〕 “Super Beckamine L-117-60”
42〃 (n-butylated melamine resin manufactured by the same company; non-volatile content = 60%) “CAB 381-2”
25〃 (Cellulose acetate butyrate manufactured by Eastman Kodatsu, USA) “Epolen N-10”
15〃 (wax made by the same company) “Alpaste 1860YL”
23〃 [Aluminum paste manufactured by Toyo Aluminum Industry Co., Ltd.; non-volatile content = 65%] ──────────────────────────
──────
total
177 Reference Example 16 (same as above) Same as Reference Example 15 except that the composition ratio was changed as shown below and the adjusted viscosity was changed to 13 to 14 seconds in Ford Cup 4. , the desired paint was obtained. Hereinafter, this will be abbreviated as paint (BC-2).

“Acridic 47-712”
160 parts [Hydroxyl group-containing acrylic resin manufactured by Dainippon Ink and Chemicals Co., Ltd.; non-volatile
Minutes = 50%〕 “Super Beckamin L-117-60”
33〃 “Alpaste 1860YL”
23〃 “First Gen Blue NK”
2 [Cyanin blue manufactured by Dainippon Ink and Chemicals]

─────────
──────────────────────

total
218 Reference Example 17 (same as above) The intended coating material was obtained in the same manner as Reference Example 15, except that the composition ratio was changed as shown below. Hereinafter, this will be abbreviated as paint (BC-3).

“Acridic 47-567”
100 parts [Hydroxyl group-containing acrylic resin manufactured by the previous company; non-volatile content = 50%] "Burnock DN-950"
18 [Polyisocyanate compound manufactured by Dainippon Ink and Chemicals Co., Ltd.; non-volatile content = 75%] “Tiepeke CR-93”
60 [Rutile type titanium oxide manufactured by Ishihara Sangyo] ──────────────────────────
───────
total
178〃

Examples
1 According to the composition ratio shown below, the viscosity was adjusted to 25 seconds using a Ford cup #4 using a diluting solvent, and the clear coat paint was prepared using a normal paint preparation method. Obtained. Below, apply this to paint (
It is abbreviated as CC-1).

Resin (A-1)
100 parts resin (A-3)
1
00 Compound (A-6)
50〃 “Super Beckamine L-117-60” 40〃 “Tinuvin 900”
1.5〃 (Ultraviolet absorber manufactured by Ciba Geigy, Switzerland) “Tinuvin 440”
1.3〃 (Radical scavenger manufactured by the same company) "Nacure 5225"
4.5 (Curing catalyst manufactured by King, USA)
Triphenylphosphine
1 〃 Dibutyltin dioctate 1
〃Examples 2 to 11 and Comparative Examples 1 and 2
Various clear coat paints were obtained in the same manner as in Example 1, except that the combinations of various resins were changed as shown in Table 6.

[0107]

[Table 6]

[0108]

[Table 7]

Example 12 The carboxyl group-containing polyester resin obtained in Reference Example 5, the hydroxyl group-containing polyester resin obtained in Reference Example 8, and the epoxy group-containing compound obtained in Reference Example 13,
According to the composition ratio shown below, the viscosity was adjusted using a diluent using a diluting solvent using a normal paint preparation method, and the viscosity was adjusted to 25 seconds in a Ford cup #4. Obtained solid color paint. Hereinafter, this will be abbreviated as paint (SC-1).

[0110] Resin (P-1)
45 parts resin (P-4)
55〃Compound (A-8)
40〃
"Super Beckamin L-117-60" 25
〃"Taipeke CR-93"
100〃"Naicure 5225"
3〃Example 13
~17 and Comparative Example 3 Various carboxyl group-containing polyester resins obtained in Reference Examples 5 to 7 and Reference Example 8
and various hydroxyl group-containing polyester resins obtained in 9 and the epoxy group-containing compound obtained in Reference Example 13,
Each coat was prepared in the same manner as in Example 12, except that the composition ratio was changed as shown in Table 7.
Bake solid color paint.

[0111]

[Table 8]

Application examples 1 to 15 and comparative application examples
1 to 3 Using various base coat paints obtained in Reference Examples 15 to 17 and various clear coat paints obtained in Examples 1 to 11 and Comparative Examples 1 and 2, as shown in Table 8. An electrodeposition primer for automobiles and an intermediate coat surfacer were applied to a mild steel plate that had been subjected to phosphorization treatment according to the following conditions.
For bake painting, first apply the base coat paint by air spray to a dry film thickness of 15 to 20 μm, then let it set for 3 minutes, then apply the top clear coat paint to a dry film thickness of 25 to 20 μm. It was coated wet-on-wet to a thickness of 40 μm, left for 20 minutes, and then dried in an electric hot air dryer at 140° C. for 20 minutes.

On the other hand, in the case of 3-coat, 2-bake painting,
After the above-mentioned two-coat one-bake painting, an overcoat clear paint was applied one hour later so that the dry film thickness was 25 to 40 μm, and after being left for 10 minutes, it was heated at 140°C in an electric hot air dryer. Drying was performed for 20 minutes.

[0114] The coating film performance of each of the thus obtained laminated coated products was evaluated. The results are summarized in the same table.

[0115] The coating film performance was roughly evaluated in the following manner. Gloss: 60 degree specular reflectance (
%).

Acid resistance: The state of change in the coated surface after immersion in a 5% sulfuric acid aqueous solution for 24 hours was visually determined. ◎...No abnormality○...Very good ×...Significant discoloration and scratch resistance...Gloss retention rate (%) of the painted surface after cleaning the painted surface with a 5% aqueous polishing powder solution at a load of 300 g/m2 and cleaning it 50 times. ).

[0117] Weather resistance: Changes in the painted surface after 24 months of actual exposure in the suburbs of Bangkok city were visually judged. ◎…No abnormality ○…Slight discoloration×…Significant discoloration

[0118]

[Table 9]

[0119]

[Table 10]

[0120]

[Table 11]

[0121]

[Table 12]

Application Example 16 Using the solid color paint obtained in Example 12, an electrodeposition primer for automobiles and an intermediate coating surfacer were applied to a mild steel plate which had been subjected to a phosphorization treatment, and on the coated plate obtained. Dry film thickness is 25-45 μm by air spray
It was coated so as to have the following properties, left to stand for 20 minutes, and then dried in an electric hot air dryer at 140° C. for 20 minutes.

[0123] Regarding the thus obtained coated product,
The coating film performance was evaluated in the same manner as Application Examples 1 to 15 and Comparative Application Examples 1 to 3. The results are summarized in Table 9.

[0124]

[Table 13]

Application Examples 17 to 21 and Comparative Application Example 4 Using the respective solid color paints obtained in Examples 13 to 17 and Comparative Example 3, electrodeposition for automobiles was applied to mild steel plates that had been subjected to phosphorization treatment. On the coated board obtained by applying the primer and intermediate coat surfacer, paint was applied by air spray so that the dry film thickness was 25 to 45 μm, left for 20 minutes, and then dried in an electric hot air dryer for 14 hours.
Drying was performed at 0° C. for 20 minutes.

Regarding the thus obtained coated product,
The coating film performance was evaluated in the same manner as Application Examples 1 to 15 and Comparative Application Examples 1 to 3. The results are summarized in Table 9.

[0127]

Effects of the Invention The thermosetting coating composition of the present invention obtained as described above has a carboxyl group-containing resin-epoxy group-containing compound curing system and a hydroxyl group-containing resin-melamine resin curing system, respectively. It is extremely useful as a so-called composite curing system, and in particular, the composition of the present invention can be used as a 2-coat, 1-bake clear paint, a 3-coat, 2-bake, overcoat clear paint, and a 1-coat, 1-bake solid color paint. By using it, it has excellent acid resistance and scratch resistance, in other words, it has excellent and well-balanced properties such as gloss, weather resistance, acid resistance, and scratch resistance, and has extremely practical value. It has a high value.

Claims (12)

[Claims] 1. A thermosetting coating composition comprising a hydroxyl group-containing resin and a carboxyl group-containing resin as base resin components, and an epoxy group-containing compound and an amino resin as curing agent components. 2. The above-mentioned hydroxyl group-containing resin has a molecular weight of 50 to 200
The thermosetting coating composition according to claim 1, which has a hydroxyl value of mgKOH/g. 3. The carboxyl group-containing resin described above is 30
It has an acid value of ~150 mgKOH/g,
The thermosetting coating composition according to claim 1. 4. The thermosetting coating composition according to claim 1, wherein the hydroxyl group-containing resin is a vinyl copolymer resin. 5. The thermosetting coating composition according to claim 1, wherein the hydroxyl group-containing resin is a polyester resin. 6. The thermosetting coating composition according to claim 1, wherein the carboxyl group-containing resin is a vinyl copolymer resin. 7. The thermosetting coating composition according to claim 1, wherein the carboxyl group-containing resin is a polyester resin. 8. The thermosetting coating composition according to claim 1, wherein the compound having an epoxy group has both an epoxy group and a hydrolyzable silyl group in one molecule. 9. The thermosetting coating composition according to claim 1, wherein the compound having an epoxy group has both an epoxy group and a hydroxyl group in one molecule. 10. The thermosetting coating composition according to claim 1, which is used as a solid paint comprising a colored pigment. 11. Any one of claims 1 to 9 used as the clear paint in laminated painting in which a base paint containing a brightening agent and/or a color pigment is coated, and then a clear paint is further laminated and crosslinked. The thermosetting coating composition described in . 12. Laminated coating in which a base paint containing a brightening agent and/or a coloring pigment is applied, a clear paint is applied thereon to cause crosslinking, and then a clear paint is further laminated on top of the base paint to cause crosslinking, The thermosetting coating composition according to any one of claims 1 to 9, which is used as each of the above-mentioned clear paints.