GB2335196A - Curable polymer composition - Google Patents

Abstract

The present invention has for its objects to a curable resin composition either comprising a Michael acceptor (a) and a Michael donor (b) or comprising said Michael acceptor (a), said Michael donor (b), and an onium salt pendant group-containing polymer (c), wherein said Michael acceptor (a) comprises an alpha,# -unsaturated carbonyl group-containing compound and/or an alpha, #-unsaturated carbonyl group-containing polymer, said Michael donor (b) comprises an active methylene or active methine group-containing compound and/or an active methylene or active methine group-containing polymer, and said onium salt pendant group-containing polymer (c) is a product obtainable by appending an onium salt (c-ii) to an acrylic polymer (c-i) or a product obtainable by appending said onium salt (c-ii) to an active methylene or active methine group-containing polymer by Michael addition reaction. In specific examples the Michael acceptor is dipentaerythritol-caprolactone ring opening hexa-acrylate adduct, pentaerythritol triacrylate, trimethylol propane triacrylate, peg400 diacrylate, hexamethyl diisocyanate/pentaerythritol triacrylate adduct, a polysiloxane terminated at each end with a 3-methacryloyloxypropyl group, and an acrylic polymer with alpha, # unsaturation adjacent a C=O group, and epoxy groups. The Michael donor is selected from various acrylics and polyesters with active -CH2- groups, trimethylolpropane tetraacrylate, some of which also have pendant tert. ammonium groups. Separate onium compounds used are tetrabutyl ammonium chloride, trimethylbenzyl ammonium dibutyl phosphate, tetrabutyl ammonium bromide. Also claimed is a multilayer coated film where the above composition when cured is the outer layer, and a method of forming such a film, where the said outer layer is heat cured.

Description

1 2335196 CURABLE RESIN COMPOSITION, COATING, MULTILAYER FILM-FORMING

METHOD, AND COATED ARTICLE

FIELD OF THE INVENTION

The present invention relates to a curable resin composition which is suited for the production of curable resin coatings, particularly automotive top-coat coatings, to a coating containing the composition, to a method of forming a multilayer coating film, and to a coated article.

BACKGROUND OF THE INVENTION

Michael addition reaction, by which an active methylene group can be added to a polarized double bond such as an a, 0-unsaturated carbonyl group in the presence of a suitable catalyst, has been applied to the crosslinking reaction of curable resin compositions such as a coating because this reaction does not give rise to reaction byproducts and partly because the newly formed bond is a chemically stable bond.

Generally in Michael addition reaction, a"Strong base is used as the catalyst in order to generate a carbanion from an active hydrogen site. Many of the prior arts applying Michael addition reaction to the crosslinking of coating and other curable resin systems uses a strong base as the catalyst.

The strong base so far in use includes alkali metal hydroxides, alkali metal alkoxIdes, quaternary ammonium hydroxides, quaternary ammonium hydrocarbonates, tertiary amines, guanidine, amidines, and tertiary phosphines, among other bases. Japanese Kokai Publication Hei-7-173262 (US Patent No. 30 5565525) and Japanese Kokai Publication Hei-8-283627 (EP Patent No. 0737726) describe a one- component thermosetting resin composition and a coating thereof utilizing a catalyst system which expresses substantially no catalyst activity at room temperature but acts as a catalyst promoting a Michael addition reaction only at the baking temperature.

2 This catalyst system includes an onium salt, which by itself has no catalyst activity for the promotion of Michael addition reaction, and either an epoxy compound or a 5_ membered-ring carbonate compound. The epoxy compound or 5- membered-ring carbonate compound is f urther capable of coupling itself to said MIchael reaction donor or acceptor by covalent bond.

However, when, in the coating of car bodies, f or instance, a clear coating utilizing this catalyst system is applied over a color pigment -containing base coating on a wet-on-wet basis and the two coatings are baked to be cured in one operation, the quaternary ammonium salt as a catalyst component is dispersed into the base coating, thus failing to function as a catalyst f or the clear coating, with the result that the clear coating does not cure sufficiently, furthermore, the quaternary ammonium salt migrating into the base coating interferes with the curing of the base coatings.

From the state of the art, a compound as a catalyst added to a clear coating, provided that the compound'.is not liable to be dispersed Into the base coating in such a coating process, can realize a still higher quality coating utilizing a Michael addition reaction.

Furthermore, coatings not causing volatile content of solvents are required as an automotive coating for the prevention of pollution and the current trend in intermadiate coatings for car use is toward a greater emphasis on waterbased coating systems. Stated differently, automotive clear coatings are leaning more and more toward the high solid formulation. Particularly, in the automotive clear coating 30 field, the usual solid content of coatings is 45 to 60 weight % today but there has been a standing demand for the development of the so-called super-highsolid clear coating for automotive Use.

SUMMARY OF THE INVENTION v 3 In view of the state of the art, the present invention has for Its object to provide a curable resin composition with which the super-high-solid feature can be implemented while satisfying the scratch resistance, acid resistance and other basic quality requirements and which does not cause the curing trouble due to diffusion of said Michael reaction catalyst into the base coating. The present invention further provides a coating utilizing the composition, a method of forming a multilayer film, and a coated article.

The present invention, therefore, is directed to a curable resin composition either comprising a Michael acceptor (a) and a Michael donor (b) or comprising said Michael acceptor (a), said Michael donor (b) and an onium salt pendant group-contaInIng polymer (c), wherein said Michael acceptor (a) comprises an a, -unsaturated carbonyl group- containing compound and/or an a, J3 -unsaturated carbonyl group- containing polymer, said Michael donor (b) comprises an active methylene or active methine group-containing compound and/6r an active methylene or active methine group-containing polymer, and said onium salt pendant group -containing polymer (c) is a product obtainable by appending an onium salt (c-ii) to an acrylic polymer (c-i) or a product obtainable by appending said onium salt (c-ii) to an active methylene or active methine group-contalnIng polymer by MIchael addition reaction, in the case that the composition comprises said Michael acceptor (a) and said Michael donor (b), at least one of said Michael acceptor (a) and said Michael donor (b) is a product obtainable by appending said onium sait (c-ii), and said onium salt (c-ii) is at least one compound selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts and tertiary amines.

The present invention is further directed to a coating which comprises said curable resin composition as a vehicle.

4 The present invention is further directed to a method of forming a multilayer coating film which comprises forming an undercoating layer on a substrate, applying a color pigment and/or brightening agent - containing base coating, applying a top clear coating on a wet-on-wet basis, and heating the resulting film to be cured, in which said top clear coating is said coating.

The present invention is further directed to a method of forming a multilayer coating film which comprises forming an undercoating layer on a substrate, applying a color pigment -containing solid coating and heating the resulting coat to be cured, or applying a base coating and a clear coating on a wet-on-wet basis and heating the resulting coat to be cured, applying a top clear coating on a dry-on-wet basis, and heating the resulting coat to be cured, in which the top clear coating is said coating.

The present invention is directed, in a further aspect, to a multilayercoated article whose multilayer coat has an outermost layer formed from the coating.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a curable resin composition. either comprising a Michael acceptor (a) and a Michael donor (b) or comprising said Michael acceptor (a), said Michael donor (b) and an onium salt pendant group- containing polymer (c).

The curable resin composition of the present Invention is a curable resin composition which cures by Michael addition reaction. As used in this specification, the term "Michael acceptor" means the part which accepts the electron f orming a covalent bonding electron pair in said Michael addition reaction and the term "Michael donor" means the part which donates the electron forming the covalent bonding electron pair in said Michael addition reaction.

Said Michael acceptor (a) comprises an a, 0 -unsaturated carbonyl groupcontaining compound andlor an a, J3 -unsaturated carbonyl groupcontaining polymer. Said a, 0 -unsaturated carbonyl group - containing compound mentioned above means a compound containing within a molecule one or more a,,6-unsaturated carbonyl groups consisting of a, 0 - unsaturated carbon and carbonyl, and the a, 0 -unsaturated carbonyl group- containing polymer means a polymer having one or more a, 0 -unsaturated carbonyl groups consisitng of a, 0 -unsaturated carbon and carbonyl.

The a, J3 -unsaturated carbonyl group- containing compound mentioned above is not particularly restricted but includes (meth)acrylic esters of monohydrIc alcohols and (meth)acrylic esters of polyhydric alcohols. Those compounds can be used each alone or in a combination of two or more species. As used In this specification, the term n(meth)acrylic acidn means acrylic acid or methacrylic acid.

When said a, 0-unsaturated carbonyl group-containing compound is used as said Michael acceptor (a), the viscosity of the coating system can be lowered and, therefore, the solid content of the resin can be increased, thus contributing to implementation of high-solid coating formulations.

With said (meth)acrylic ester of monohydric alcohol, the crosslink density can be decreased to render the coating film flexible, while the use of said (meth)acrylic ester of polyhydric alcohol results in higher crosslink density and f ilm hardness.

The (meth)acrylic ester of polyhydric alcohol is not particularly restricted but includes ethylene glycol di(meth)acrylate. diethylene glycol dl(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol triacrylate, glycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol (penta)hexa(meth)acrylate, hydrogenated bisphenol A v i 6 diacrylate, hydrogenated dicyclopentadienyl diacrylate, neopentyl glycol pivalate (meth)acrylate, dicyclopentadiene (meth) acrylate, trimethylolpropane- ethylene oxide (E0) adduct tri(meth)acrylate. trImethylolpropane-propylene oxide (PO) adduct tri(meth)acrylate, and dipentaerythritol-caprolactone adduct hexa(meth)acrylate. Those esters can be used each alone or in a combination of two or more species. As used in this specification. the term "(meth)acrylate" means acrylate andlor methacrylate.

Said a, 0 -unsaturated carbonyl group -containing polymer is not particularly restricted but includes polyester acrylate resin,-unsaturated polyester resin, fatty acid-containing polyester, f at and oil, epoxy acrylate resin, urethane acrylate resin, a, 0 -unsaturated carbonyl group -containing acrylic resin, polyether acrylate resin, and (meth)acryloyl groupcontaining silicone oligomer. Those polymers can be used each alone or in a combination of two or more species.

Said polyester acrylate resin, said unsaturated polyester resin, and said fatty acid- containind polyester are not particularly limited but include, among others, the resins obtainable by the conventional polycondensation reaction technology using a polybasic acid and a polyhydric alcohol, optionally together with a lactone, semi-drying oil, non-drying oil, andlor other substances.

The polybasic acid mentioned above is not particularly restricted but includes aromatic polybasic acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalle acid, etc.; alicyclic polybasic acids such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, etc.; and aliphatic polybasic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedIcarboxylic acid, himic anhydride. maleic acid, maleic anhydride, f umaric acid, itaconic acid, trimellitic acid, trimellitic anhydride, pyromellitic anhydride, etc. Those 7 compounds can be used each alone or in a combination of two or more species.

For the production of said unsaturated polyester resin, a, J3 unsaturated dicarboxylic acids such as maleic acid, maleic anhydride, fumaric acid, etc. are used as the polybasic acid and used optionally together with other polybasic acids. The unsaturated polyester resin mentioned above has heretofore been used in large quantities in FRP and other molding applications.

The polyhydric alcohol mentioned above is not particularly restricted but includes ethylene glycol, 1,3propanediol, 1,4- butanediol, propylene glycol, 1,3-butylene glycol, 1, 6 -hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, tetramethylene glycol, cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, bIsphenol hydroxypropyl ether, glycerin, trimethylolpropane, pentaerythritol, and dipentaerythritol. Those alcohols can be used each alone or in a combination of two or more.specles. 20 The lactone mentioned above is not particularly restricted but includes -r - butyrolactone and E -caprolactone. Those lactones can be used each alone or in a combination of two or more species. The semi-drying oil mentioned above Is not particularly restricted but includes soybean oil, safflower oil and tall oil. The non- drying oil Is not particularly restricted but includes coconut oil and castor oil. Those oils can be used each alone or in a combination of two or more species.

The polyester acrylate resin, unsaturated polyester resin, and fatty acid-containing polyester mentioned above preferably have oil lengths not over 40%. The more preferred range of oil length is not over 30%. The fatty acid-containing polyester mentioned above is suitable for use as a pigment dispersing resin. 35 The oil and fat mentioned above are not particularly a restricted but include the semi-drying oil and non-dryIng oil, inclusive of fatty acids thereof.

The epoxy acrylate resin mentioned above is not particularly restricted but includes the resin obtainable by a ring-opening addition reaction involving the epoxy ring of a bisphenol, novolac, or other type of epoxy resin and (meth)acrylic acid.

The urethane acrylate resin mentioned above Is not particularly restricted but includes the resin obtainable by the condensation of a polyhydric alcohol with a monobasic acid andlor a polybasic acid and subsequent addition of a (meth)acryloylated isocyanate prepolymer to the terminal hydroxyl group of the condensation product, thus including resins which may be represented by the following formulas.

Incidentally, as used in this specification, the term "(meth)acryloyln means acryloyl andlor methacryloyl.

(EGn+l PAn,) - (IPDI HEA)n+i wherein EG represents ethylene glycol, PAn represents phthalic acid, IPDI represents isophorone diisocyanate, HEA represents 2-hydroxyethyl acrylate, and n represents the number of moles. Thus, the resin of the formula is the product obtainable by adding the reaction product of isophorone diisocyanate with hydroxyethyl acrylate to the condensation product between ethylene glycol (n+l moles) and phthalic acid (n moles).

(PG.., PAn.) - (IPDI HEA),+1 wherein PG represents propylene glycol.

The polyhydric alcohol mentioned above Is not particularly restricted but includes the polyhydrIc alcohols mentioned above.

The monobasic acid mentioned above is not particularly restricted but includes acetic acid and benzoic acid.

The polybasic acid mentioned above is not particularly restricted but includes the polybasic acids mentioned above.

The (meth)acryloylated isocyanate prepolymer is not particularly restricted but includes the prepolymer obtainable 9 by the (meth) acryloylation of a diisocyanate, isocyanate prepolymer or the like by the conventional technology.

The diisocyanate mentioned above is not particularly restricted but includes aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI), trimethylhexamethylene diisocyanate, isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (HXDI), etc. and aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), etc. 10 Those compounds can be used each alone or in a combination of two or more species.

The isocyanate prepolymer mentioned above is not particularly restricted but includes the biurets, isocyanurates, and adducts, e.g. to trimethylolpropane, di (meth) acrylate, etc., of said diisocyanate compounds. Those prepolymers can be used each alone or in a combination of two or more species.

The urethane acrylate resin mentioned above further includes the resin obtainable by the addition reaction of a diisocyanate-terminated prepolymer available from a hydroxy group- containing compound (X moles) and a diisocyanate compound (X+1 moles) with a hydroxyl group- containing acrylic monomer andlor a hydroxyl group- containing acrylic polymer.

The hydroxyl group -containing compound mentioned above is not particularly restricted but includes hydroxyl groupcontaining acrylic monomers such as 2-hydroxyethyl (meth)acrylate. 2-hydroxypropyl (meth)acrylate, 4hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, pentaerythritol tri(meth)acrylate. dipentaerythritol penta(meth)acrylate. trimethylolpropane di(meth)acrylate, glycerol di(meth)acrylate, Cardura E10 (trade name; Shell Petrochemical) - (meth) acrylic acid adduct, Placcel FM- 1 (trade name; 2- hydroxyethyl(meth)acrylate-polycaprolactone adduct; Daicel Chemical), pentaerythritol triacrylate, dipentaerythritol pentaacrylate, etc.; the polyhydric alcohols mentioned above; and caprolactone polyols such as PCD300, PCD540 and PCT300 (all trade names, Daicel Chemical). Those compounds can be used each alone or in a combination of two or more species. 5 The hydroxyl group- containing acrylic polymer mentioned above is not particularly restricted but includes the polymers obtained by polymerization of the hydroxyl group-containing acrylic monomers, with other acrylic monomers, and optionally together, ethylenically unsaturated monomers other than acrylic monomers, by the conventional polymerization technology. The acrylic monomers mentioned above are not particularly restricted but Include (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)ac-rylate, phenyl (meth)acrylate, benzyl (meth)acrylate, etc.; amide-containing acrylic monomers such as acrylamide, methylenebisacrylamide, etc.; and nitrile -containing monomers such as acrylonitrile etc. Those monomers can be used each alone or in a combination of two or more species.

Said ethylenically unsaturated monomers other than acrylic monomers are not particularly restricted but include styreniQ monomers such as styrene, a -methylstyrene, etc.; acids such as Itaconic acid, maleic acid. and vinyl esters such as vinyl acetate etc. Those monomers can be used each alone or in a combination of two or more species.

Said urethane acrylate resin further includes the resin obtainable by the direct addition of a hydroxyl group- containing acrylic monomer andlor a hydroxyl group -containing acrylic polymer to an isocyanate prepolymer.

The use of the urethane acrylate resin contributes to flexibility of the cured film.

The a, 0 -unsaturated carbonyl group -containing acrylic resin mentioned above is not particularly restricted but 11 Includes the resin obtainable by the epoxy ring-opening addition reaction involving (meth) acrylic acid and the resin obtainable by the acylation reaction of the hydroxyl group'with (meth)acrylic acid. To be specific, the acrylated (meth) acrylate resin obtainable by reacting (meth) acrylic acid with an epoxy-containing acrylic resin prepared by copolymerizIng an epoxy groupcontaining acrylic monomer, e.g. glycidyl (meth)acrylate, with a different acrylic monomer andlor an ethylenically unsaturated group - containing monomer other than acrylic monomers; and the acrylated urethane (meth)acrylate resin obtainable by subjecting a hydroxyl group- containing acrylic resin to the addition reaction with an adduct of an isocyanate prepolymer with hydroxyl groupcontaining acrylic monomer andlor hydroxyl group-containing acrylic polymer adduct, methacryloyl isocyanate (MAI), methacryloyloxyethyl isocyanate (MOA) or the like. Those resins can be used each alone or in a combination of two or more species.

The acrylic monomer mentioned above is not particularly restricted but includes the same acrylic monomers and hydroxyl group- containing acrylic monomers as mentioned above.

The ethylenically unsaturated group- containing monomer other than acrylic monomers, mentioned above, is not particularly restricted but- includes the same compounds as those mentioned above.

The a, 0 -unsaturated carbonyl group -containing acrylic resin mentioned above further includes the resin obtainable by reacting a carboxyl groupcontaining acrylic resin with an epoxy group-containing acrylic monomer such as glycidyl (meth)acrylate. among others.

The carboxyl group-containing acrylic resin mentioned above is not particularly restricted but includes the resin obtainable by copolymerizing a carboxyl group-containing monomer, e.g. acrylic acid, methacrylic acid, itaconic acid or the like, with an acrylic monomer, optionally together with a 12 hydroxyl group-containing acrylic monomer andlor an ethylenically unsaturated group -containing monomer other than acrylic monomers.

The acrylic monomer, hydroxyl group -containing acrylic 5 monomer and ethylenically unsaturated group-containing monomer other than acrylic monomers respectively are not particularly restricted but include the same compounds as mentioned above.

The a, 0 -unsaturated carbonyl group -containing acrylic 10 resin further includes the resin obtainable by acylating a hydroxyl group- containing acrylic resin with acrylic acid or methacrylic acid, or a reactive derivative thereof (e.g.

acrylic acid chloride, methacrylic acid chloride, etc.), and the resin obtainable by subjecting a hydroxyl group- containing 15 acrylic resin and a lower alkyl ester of acrylic acid, methacrylic acid or the like to ester exchange to introduce an a,J3- unsaturated carbonyl group.

The hydroxyl group-containing acrylic resin mentioned above is not particularly restricted but includes the same resins as mentioned above.

The lower alkyl ester of acrylic acid, methacrylic acid or the like, mentioned above, is not particularly restricted but includes the corresponding methyl ester.

The polyether acrylate resin mentioned above Is not 25 particularly restricted but includes polyethylene glycol di(meth)acrylate.

The (meth) acryloyl group -containing silicone oligomer is not particularly restricted but includes polydiorgano- siloxanes having a 3-methacryloyloxypropyl group at terminal 30 ends.

Said Michael acceptor (a) further includes (meth) acryloyl groupcontaining fluorine series ollgomers and (meth)acryloyl group-containing fluorine series monomers.

As said Michael acceptor (a), the acceptor compounds 35 mentioned hereinbefore can be used each alone or in a 13 combination of two or more species.

The number average molecular weight (Mn) of said Michael acceptor (a) is preferably within the range of 100 to 100 A00. The more preferred range of Mn is 100 to 10,000. Inclusion of a Michael acceptor (a) having a number average molecular weight (Mn) of 100 to 600 is preferred because of implementing a still higher- solid coating. Particularly when said Michael acceptor (a) contains a monomer species, the super-high- solid feature can be more positively implemented.

The double bond equivalent of said Michael acceptor (a) is preferably 85 to 10,000, more preferably 100 to 1,000. As used in this specification, the term "equivalent" means the molecular weight per a functional group and represents the value on a solid basis.

Said Michael donor (b) f or use in the present invention comprises an active methylene or active methine groupcontaining compound andlor an active methylene or active methine group-containing polymer. The active methylene or active methine group-containing compound means: a compound containing one or more active methylene or active methine groups within the molecule. Thus, active methylene group -containing compounds and active methine group-containing compounds can both be used. The active methylene or active methine group-containing polymer mentioned above means a polymer containing one or more active methylene or active methine groups within the molecule. Thus, active methylene group -containing polymers and active methine group -containing polymers can both be used.

The active methylene group -containing compound mentioned above is not particularly restricted but includes active methylene group- containing carboxylic acid compounds such as acetoacetic acid, malonic acid, cyanoacetic acid, and their derivatives and half esters and active methylene groupcontaining carboxylic acid esters such as acetoacetic esters, malonic esters, cyanoacetic esters, and their derivatives.

14 Those compounds can be used each alone or in a combination of two or more species. Among them, the active methylene group-containing carboxylic acid compounds are liable to pyrolysis and, hence, act as catalytic poison In said Michael addition reaction. Therefore, the active methylene groupcontaining carboxylic esters which are not liable to pyrolysis and, hence, hardly act as catalytic poison are preferred.

The still more preferred are malonIc esters and their derivatives because of the low chances for steric hindrance involved in said Michael reaction.

Among the active methylene group-cntaining compounds and active methylene group-containing polymers, the compound or polymer containing a plurality of active methylene groups within the molecule is not particularly restricted but includes the transesterif ication reaction product between a polyhydric alcohol or a polyol and an active methylene group-containing carboxylic ester, the esterification reaction product of a polyhydric alcohol or a polyol with an active methylene group-containing carboxylic acid compound, the, 7reaction product of a polyamine compound with a diketene, and the addition reaction product of an active methylene group containing acrylic resin and an isocyanate compound with an active methylene group- containing compound. Those compounds can be used each alone or in a combination of two or more species.

The transesterification reaction product between a polyhydric alcohol or a polyol and an active methylene group -containing carboxylic ester Is obtainable by subjecting the polyhydric alcohol or polyol and active methylene group-containing carboxylic ester to transesterification In the routine manner and has a structure derived from the active methylene group-containing carboxylic ester used.

The esterif ication product of a polyhydric alcohol or a polyol with an active methylene group-containing carboxylic acid compound is the compound obtainable by subjecting the polyhydric alcohol or polyol and the active methylene is group- containing carboxylic acid compound to esterif ication in the routine manner and has a structure derived from the active methylene group-containing carboxylic acid compound used.

The polyhydric alcohol mentioned above is not particularly restricted but includes the same alcohols as those mentioned above. The polyol mentioned above is not particularly restricted but includes acrylic polyols, polyester polyols, polyether polyols, epoxy polyols, polyurethane polyols, and silicone polyols. Those polyhydric alcohols and polyols can be used either alone or in a combination of two or more species.

The active methylene group -containing carboxylic ester and active methylene group -containing carboxylic acid compound, mentioned above, are not particularly restricted but include the same compounds as mentioned above. Those compounds can be used each alone or in a combination of two or more species. The polyester resin containing a plurality of active methylene groups can be obtained by the polycondensation of the polyhydric alcohol or polyol with a malonic ester, for instance.

Referring to the compound or polymer containing a plurality of active methylene groups, the transesterif icatIon product and the polyester resin containing a plurality of active methylene groups are preferred in view of their high resistance to pyrolysIs, low chances for steric hindrance, and low risks f or acting as catalytic poison in said Michael reaction. The still more preferred is the- oligomer or polyester resin (polyesterpolyol) obtainable by the polycondensation reaction between the polyhydric alcohol or polyol and a malonic ester.

The reaction product of a polyamine compound with a diketene is a compound obtainable by reacting a polyamine compound with a diketene in the routine manner.

The polyamine compound mentioned above is not particularly restricted but includes ethylenediamine, 1,3diaminopropane, 1,4-diaminobutane, 1,6hexanediamine, 1,12- diaminododecane, 1,2-diaminocyclohexane, phenylenediamine, 16 piperazine, 1,2-diaminotoluene, diethyltoluenediamine, N,N'-bis(2- aminopropyl)ethylenediamine and N,N1-bis(3aminopropyl)-1.3-propanediamine. Those compounds can be'used each alone or in a combination of two or more species.

The active-methylene group-containing acrylic resin mentioned above Is not particularly restricted but includes the resin obtainable by copolymerizing an active methylene group-containing acrylic monomer with an acrylic monomer or optionally with a hydroxyl group-containing acrylic monomer and/or an ethylenically unsaturated group -containing monomer other than acrylic monomers.

The active methylene group-containing acrylic monomer mentioned above is not particularly restricted but includes (meth)acrylic monomers such as 2acetoacetoxyethyl (meth)acrylate etc.; alkoxymalonyloxyethyl (meth)acrylates such as ethyl 2-(methacryloyloxy)ethyl malonate etc.; 2cyanoacetoxyethyl esters, N- (2- cyanoacetoxyethyl) acrylamide, N(2-propionylacetoxybutyl)acrylamide, N-4(acetoacetoxymetyl)benzylacrylamide, N-(2-acetoacetamidoethyl)acrylamide, and N- (2acetoacetamidoethyl)methacrylamide. Those monomers can be used each alone or in a combination of two or more species. Among them, alkoxymalonyloxyethyl (meth)acrylates are preferred in view of their low chances for steric hindrance In Michael addition reaction.

The acrylic monomer, hydroxyl group-containing acrylic monomer and ethylenically unsaturated group-containing monomer other than the acrylic monomers are not particularly restricted but include the same compounds as respectively mentioned above.

The addition reaction product between an isocyanate compound and an active methylene group- containing compound is the compound which can be obtained by an addition reaction of an isocyanate compound with an active methylene group- containing compound in the routine manner.

17 The isocyanate compound mentioned above is not particularly restricted but includes the diisocyanate compounds and isocyanate prepolymers and the polyisocyanates obtainable by terminal modification of polyols with a diisocyanate.

The active methylene group-containing compound is not particularly restricted but includes the compounds mentioned above.

The addition reaction between the isocyanate compound and the active methylene group -containing compound is carried out using a polyfunctional species for one of the reactants and a monofunctional species for the other. For example, when the polyisocyanate obtained by terminal modification of a polyol with a dilsocyanate is used as the isocyanate compound, a malonic ester or the like is used as the active methylene group- containing compound.

Conversely when a monof unctional isocyanate compound is used as the isocyanate compound, the reaction is carried out using a polyfunctional active methylene compound or a polyf unctional active methylene polymer as the active methylene group-containing compound. The compound or polymer containing a plurality of active methine groups within the molecule is not particularly restricted but includes the transesterification reaction product between a methanetricarboxylic acid trialkyl ester and a polyhydric alcohol or a polyol and the addition reaction product between an isocyanate compound and an active methylene group-containing compound. Those compounds or polymers are disclosed in European Patent No. 310011, for instance. 30 As said Michael donor (b), a compound containing both active methylene and active methine groups can also be used. The compound containing both active methylene and active methine groups is not particularly restricted, and the combination use of the active methylene group-containing compound andlor active methylene group -containing polymer with 18 the active methine group-containing compound andlor active methine group -containing polymer may also be regarded as such a compound. Of course, it may be a compound and/or polymer containing both active methylene and active methine groups. As specific examples, an acrylic resin containing both active methylene and active methine groups and a polyester polyol synthesized using a malonic ester as one of the starting materials can be mentioned.

The acrylic resin containing both active methylene and active methine groups is not particularly restricted but includes the resins obtainable by copolymerizing an active methylene group -containing acrylic monomer, an active methine group-containing acrylic monomer. and an acrylic monomer, optionally together with a hydroxyl group- containing acrylic 15 monomer andlor an ethylenically unsaturated group- containing monomer other than acrylic monomers.

The methylene group- containing acrylic monomer, acrylic monomer, hydroxyl group-containing acrylic monomer, and ethylenically unsaturated group -containing monoffier other than 20 acrylic monomers are not particularly restricted but include the same compounds as respectively mentioned above. As said Michael donor (b), the compounds can be used each alone or In a combination of two or more species. The number average molecular weight (Mn) of said Michael 25 donor (b) is pref erably within the range of 100 to 100, 000, more preferably 100 to 10, 000. Inclusion of a Michael donor (b) with a number average molecular weight (Mn) of 100 to 500 is pref erred because, in such a formulation, the high-solid feature of the resulting coating is better expressed. Particularly when said Michael donor (b) contains a monomer species, super-high- solid feature may be implemented.

The active hydrogen equivalent of said Michael donor (b) is preferably within the range of 50 to 10, 000, more preferably 80 to 5,000.

The onium salt pendant group- containing polymer (c) for 19 use in the present invention is not restricted but contains a product obtainable by appending said onium salt (c-ii) to an acrylic polymer (c- i) and a product obtainable by appending'said onium, salt (c-ii) to an active methylene or active methIne group -containing polymer by Michael addition. Those products can be used each alone or in a combination of two or more species. As used in this specification, the term "product obtainable by appending said onium salt (c-ii)" means one having one or more onium salts (c-ii) bound to its main chain andlor side chain of the polymer.

The acrylic polymer (c-i) mentioned above is not particularly restricted but includes the polymer obtainable by polymerizing an acrylic monomer, optionally with a hydroxyl group-containing acrylic monomer andlor an ethylenically unsaturated group-containing monomer other than the acrylic monomers.

The acrylic monomer, hydroxyl group -containing acrylic monomer, and ethylenically unsaturated group-contalning monomer other than acrylic monomers respectively include the corresponding monomers mentioned above.

The active methylene or active methine group- containing polymer for use in the preparation of the product obtainable by appending said onium salt (c-ii) to the active methylene or active methine group- containing polymer by Michael addition is not particularly restricted but includes the corresponding polymers mentioned above. As a specific example, a malonic acid-based polyester can be mentioned. The malonic acid-based polyester mentioned above can be obtained by using malonic acid as one of the starting materials in the production of a polyester by the polycondensation reaction. In this case, the product obtainable by appending said onium salt (c-ii) to an active methylene or active methine group- containing polymer by Michael addition is a polyester condensate.

The first embodiment of the curable resin composition of the present invention comprises said Michael acceptor (a) and said Michael donor (b). In this embodiment, at least one of said Michael acceptor (a) and said Michael donor (b) is the product obtainable by appending said onium salt (c-ii).

Thus, when the curable resin composition of the present invention comprises said Michael acceptor (a) and said Michael donor (b), it does not contain the onium salt pendant group-containing polymer (c). Therefore, said Michael acceptor (a) andlor said Michael donor (b) is the product obtainable by appending said onium salt (c-ii) so that the component thus carrying the onium salt (c-ii), which functions as a Michael reaction catalyst, will not be liable to immigrate the base coat to thereby accomplish the object of the present invention.

The first embodiment includes, (1) the case in which said Michael acceptor (a) is the product obtainable by appending said onium salt (c-ii) while said Michael donor (b) is not the product obtainable by appending said onium salt (c-ii), (2) the case in which said Michael acceptor (a) is not the product obtainable by appending said onium salt (c-ii) while said Michael donor (b) is the product obtainable by appending said onium salt (c-ii), and (3) the case in which both of said Michael acceptor (a) and said Michael donor (b) are the products obtainable by appending said onium salt (c-ii).

In those cases, it is suf f icient that only a part of said Michael acceptor (a) and/or said Michael donor (b) has the pendant onium salt (c-ii). In other words, it is not necessary that the whole of said Michael acceptor (a) andlor said Michael donor (b) has pendant onium salt (c-ii).

Said Michael acceptor (a) being the product obtainable by appending said onium salt (c-ii) is the a, 0 -unsaturated carbonyl group-containing polymer mentioned above and said Michael donor (b) being the product obtainable by appending said onium salt (c-ii) is the active methylene or active methine group-containing polymer mentioned above.

Therefore, said Michael acceptor (a) being the product 21 obtainable by appending said onium salt (c-ii) is an onium salt pendant group/ a. J3 -unsaturated carbonyl group- containing polymer, and said MIchael donor (b) carrying the pendant oinium salt (c-ii) Is an onium salt pendant grouplactive methylene or active methine group-containing polymer.

This embodiment is advantageous in that since an onium salt pendant groupcontaining polymer (c) need not to be added as mentioned below, the production process is simplified.

In this first embodiment of the present invention, the catalyst activity of the pendant onium. salt (c-ii) makes it easy for said Michael donor (b) to form a carbanion from its active hydrogen site to thereby promote said Michael reaction. In this sense, said Michael donor (b) is preferably one being the product obtainable by appending the onium salt (c-ii).

The second embodiment of the curable resin composition of the present invention comprises said Michael acceptor (a), said Michael donor (b) and the onium salt pendant groupcontaining polymer (c). This embodiment includes the case in which the onium salt pendant group-containing polymer (c) comprises the acrylic polymer (c-i) being the product obtainable by appending said onium salt (c-ii) and the active methylene or active methine group- containing polymer being the product obtainable by appending said onium salt (c-ii) by Michael reaction and the like. 25 In this embodiment, said Michael acceptor (a) and said Michael donor (b) may be the product obtainable by appending said onium salt (c-ii) or is not the product obtainable by appending said onlum salt (c-ii). Thus, when the curable resin composition of the present invention comprises said Michacil acceptor (a), said Michael donor (b) and said onium salt pendant group -containing polymer (c), the composition includes said onium salt pentand group- containing polymer (c) and then said Michael acceptor (a) and/or said Michael donor (b) is the product obtainable by appending by said onium. salt (c-ii) or is not the product 22 obtainable by appending by said onium salt (c-ii). In this embodiment, the component(s) having the pendant onium salt (c-ii), which functions as a Michael reaction catalyst, it not liable to immigrate into the base coat to thereby accomplish 5 the object of the present invention.

Thus, the second embodiment containing the onium salt pendant group containing polymer (c) includes, (1) the case in which said MIchael acceptor (a) has the pendant onium salt (c-ii) while said Michael donor (b) is not the product obtainable by appending by said onium salt (c-ii), (2) the case in which said Michael acceptor (a) is not the product obtainable by appending by said onium salt (c-ii) while said Michael donor (b) is the product obtainable by appending by said onium salt (c-li), (3) the case in which both of said Michael acceptor (a) and said Michael donor (b) are the products obtainable by appending said onium salt (c-ii), and (4) the case in which neither said Michael acceptor (a) nor said Michael donor (b) is the product obtainable by appending said onium salt (c-ii).

When, in this embodiment, said Michael acceptor (a) andlor said Michael donor (b) is the product obtainable by appending said onium salt (c-ii), it is sufficient that only a part of said Michael acceptor (a) and/or said Michael donor (b) is the product obtainable by appending said onium. salt (c-ii). Therefore, the whole of said Michael acceptor (a) andlor said Michael donor (b) need not have the pendant onium salt (c-ii).

In whichever of the first and second embodiments of the curable resin composition of the present invention, at least one of the components of the curable resin composition is a polymer having the pendant onium salt (c-ii).

The onium. salt (c-ii) is at least one selected from the group consisting of quaternary ammonium salt, quaternary phosphonium. salt, tertiary sulfonium salt and tertiary amine, and may for example be an onium salt having a copolymerizable ethylenically unsaturated group.

23 As used In this specification, the term wonium salC means any and all of quaternary ammonium salt, quaternary phosphonium salt, tertiary sulf onium salt, and tertiary amine.

The onium salt having a copolymerizable ethylenically unsaturated group is not particularly restricted but includes tertiary amine monomers such as tertiary aminoalkyl (meth)acrylate etc.; quaternary amine monomers such as quaternized aminoalkyl (meth) acrylate, quaternized aminoalkyl (meth)acrylamide, quaternary ammonium (meth)acrylate, etc.; and quaternary phosphinoalkyl (meth)acrylate, quaternary phosphonium (meth)acrylate, and other monomers. Those compounds can be used each alone or in a combination of two or more species.

Said onium salt having a copolymerizable ethylenically unsaturated group is not particularly restricted but includes 2(methacryloyloxy)ethyltrimethylammonium chloride, 2(methacryloyloxy)ethyltrimethylammonium bromide, methacryloylaminopropyltrimethylammonium chloride, methacryloylaminopropyltrimethylammonium bromide, 20 tetrabutylammonium (meth)acrylate, tetramethylammonium (meth)acrylate, trimethylbenzylammonium (meth)acrylate, methacryloyloxyethyltrimethylammonium dimethyl phosphate, trioctyl(4vinylbenzyl)phosphonium chloride, tri-nbuty1(2methacryloyloxyethyl)phosphonium chloride, dimethylaminoethyl methacrylate, 2-acid phosphoxyethyl methacrylate ditetrabutylammonium salt, tri-n-butylmethacryloyloxyethylphosphonium chloride, and tri-n-octyl-4-vinylbenzylphosphonium chloride. Those compounds can be used each alone or in a combination of two or more species.

Said acrylic polymer (c-i) being the product obtainable by appending said onium salt (c-ii) is not particularly restricted but Includes quaternary ammonium salt pendant group-containing acrylic resins.

The product obtainable by appending said onium salt 24 (c-li) to active methylene or active methine group -containing polymer by Michael reaction is not particularly restricted but includes quaternary ammonium pendant group-containing polyester condensates.

There is no particular limitation on the method of appending said onium salt (c-ii) to the acrylic polymer (c i). For example, the onium salt pendant group can be appended to the main chain andlor side chain of the polymer by polymerizing the pendant onium salt (c-ii) with the monomers constituting the polymer by a conventional polymerization technique.

There is no particular limitation on the method of appending said onium salt (c-li) to the active methylene or active methine group- containing polymer by Michael reaction.

For example, the onium salt pendant group can be appended to the main chain and/or side chain of the polymer by adding the pendant onium salt (c-ii) to the active methylene or active methine group of the active methylene or active methine group- containing polymer by a conventional Michael reaction.

The a, 0 -unsaturated carbonyl group -containing polymer being the product obtainable by appending an onium salt is not particularly restricted but includes acrylic resin containing the a, 0 -unsaturated carbonyl group/ quaternary ammonium salt pendant group obtainable by appending a quaternary ammonium salt to the a, 0 -unsaturated carbonyl group -containing acryl resin.

The acrylic resin containing the a, J3 -unsaturated carbonyl group/quaternary ammonium salt pendant group mentioned above can be produced as follows. Thus. when the carboxyl group-containing acrylic resin and the epoxy group-containing acrylic monomer such as glycidyl (meth)acrylate are subjected to ring- opening addition reaction to introduce the a, 0-unsaturated carbonyl group into the carboxyl group -containing acrylic resin and thereby provide the a, 0 -unsaturated carbonyl group -containing acrylic resin, an epoxy group -containing quaternary ammonium salt is used as part of the epoxy group -containing acrylic monomer and reacted at one time or In sequence to prepare the a -unsaturated carbonyl group-containing acrylic resin.

The epoxy group-containIng quaternary ammonium salt mentioned above is not particularly restricted but includes glycidyltrJ-methylammonium chloride and glycidyltrimethylammmonium bromide. Those salts can be used each alone or in a combination of two or more species.

Said Michael donor (b) being the product obtainable by appending an onium salt is not particularly restricted but includes the compound obtainable by reacting an epoxy group-containing quaternary ammonium salt with an active methylene grouplcarboxyl group-containing acrylic resin.

Preferred is an active methylene group /quaternary ammonium salt pendant group-containing acrylic resin which is the active methylene groupcontaining acrylic resin having the pendant onium salt.

The epoxy group-containing quaternary ammonium salt mentioned above is not particularly restricted but includes the same salts as mentioned above.

The active methylene group-containing acrylic resin being the product obtainable by appending an onium salt can be produced by copolymerizing the copolymerizable ethylenically unsaturated group- containing onium. salt in the stage where the active methylene group- containing acrylic resin is prepared by copolymerization.

In this case, the preferred examples of the copolymerizable ethylenically unsaturated group-containing onium salt are tertiary aminoalkyl (meth) acrylate, quaternized aminoalkyl (meth)acrylate, quaternized aminoalkyl (meth)acrylamide, quaternary ammonium (meth)acrylate, quaternary phosphinoalkyl (meth)acrylate, and quaternary phosphonium (meth)acrylate.

When the tertiary amine monomer is used in the 26 copolymerIzation reaction, it is also possible to prepare an active methylene group-containing acrylic resin having the pendant tertiary amine group and then reacting this resin further with a quaternizing agent such as an alkyl hallde to 5 quaternize the tertiary amino group.

Said Michael donor (b) being the product obtainable by appending an onium salt further includes the active methylene group-containing acrylic resin having a pendant tertiary sulfonium salt.

The active methylene group- containing acrylic resin having a pendant tertiary sulfonium salt can be produced by reacting the glycidyl group in acrylic resin which has active methylene group containing glycidyl group with a sulf ide-acid mixture to thereby convert the glycidyl group to the tertiary sulfonium pendant group.

Among the onium salt pendant groups which may be introduced to the polymer being the product obtainable by appending said onium salt (c-ii), the pendant groups which function as Michael reaction catalysts by themselves are tertiary amine-pendant groups derived from tertiary amines, and in the case that counter anions are provided, onium ion-pendant groups derived from onium ions such as hydroxide anion, carbonate anion. monocarboxylate anion, etc. When the polymer being the product obtainable by appending said onium salt (c-ii) has any of those pendant groups, the curable resin composition can be cured without addition of a cocatalyst (c-iii) to be described in detail hereinafter.

Among the onium salt pendant groups derived from counter anions, the onium. salt pendant groups derived f rom halide anions and anions such as phenolic hydroxyl group -containing monobasic carboxylate, polybasic carboxylate, nitrate, sulfonate, sulfate, acid sulfuric ester, sulfite. phosphate, acid phosphoric ester, and other anions are substantially incapable of acting as Michael reaction catalysts by themselves but function as Michael reaction catalysts upon heating in the 27 presence of a cocatalyst (c-iii).

Said cocatalyst (c-iii). when used in the curable resin composition comprising said Michael acceptor (a) and said Michael donor (b), is used as a component independent of said Michael acceptor (a) and said Michael donor (b), and/or, at least one of said Michael acceptor (a) and said Michael donor (b) Is the product obtainable by appending said cocatalyst (c-iii).

Among these cases, when said Michael acceptor (a) andlor said Michael donor (b) is the product obtainable by appending the cocatalyst (c-iii), it is sufficient that only a part of said Michael acceptor (a) andlor said Michael donor (b) have the cocatalyst (c-iii) appended as a pendant group, that is to say it is not necessary that the whole of said Michael acceptor (a) andlor Michael donor (b) have the cocatalyst (c-iii) appended as a pendant group.

When the curable resin composition comprises said Michael acceptor (a), said Michael donor (b), and said onium. salt pendant group- containing polymer (c), the cocatalyst (c-iii) is used as a component independent of said Michael acceptor (a), said Michael donor (b), and said onium. salt pendant groupcontaining polymer (c), and/or, at least one of said Michael acceptor (a), said Michael donor (b) and said onium salt pendant group-containing polymer (c) is the product obtainable by appending said cocatalyst (c-iii).

Among these cases, when at least one of said Michael acceptor (a), said Michael donor (b), and said onium salt pendant group -containing polymer (c) is the product obtainable by appending said cocatalyst (c-iii), it is sufficient that only a part of at least one of said Michael donor (b) and said onium salt pendant group- containing polymer (c) has said cocatalyst (c-iil) appended as a pendant group, that Is to say it is not nesessary that the whole of at least one of said Michael donor (b) and said onium salt pendant group-containing polymer (c) has the cocatalyst (c-iii) appended as a pendant group.

28 In this connection, said Michael acceptor (a) being the product obtainable by appending said cocatalyst (c-iii) is preferably the a J3unsaturated carbonyl group-containing polymer and said Michael donor (b) being the product obtainable by appending said cocatalyst (c-iii) is preferably the active methylene or active methine group-containing polymer.

The cocatalyst (ciii) is preferably at least one selected from among epoxy compounds and 5-membered-ring carbonate compounds.

When said cocatalyst (c-iii) is used as an independent component, the preferred epoxy compound is not particularly restricted but includes glycidyl ethers such as phenyl glycidyl ether, bisphenol type epoxy resin, the reaction product between epichlorohydrin and a polyhydric alcohol, etc.; glycidyl esters such as glycidyl benzoate, glycidyl (meth)acrylate, glycidyl (meth)acrylate polymer, etc.; alicyclic epoxy compounds or polymers such as 4-(3,4-epoxycyclohexyl)methoxycarbonyl1,2epoxycyclohexane, 3,4-epoxycyclohexanemethanol (meth)acrylate, 3,4-epoxycyclohexanemethanol (, meth)acrylate polymer, etc.; a - olef in epoxides such as epoxyhexadecane etc.; diglycidyl phthalates such as diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, etc.; and diglycidyl ethers such as hydrogenated bisphenol A diglycidyl ether, etc. Those epoxy compounds can be used each alone or in a combination of two or more species.

The epoxy compound preferably has a number average molecular weight (Mn) within the range of 142 to 100,000, particularly 400 to 10,000, and an epoxy equivalent of 142 to 100,000, particularly 200 to 5,000.

There is no limitation on the method for appending the epoxy compound to said Michael acceptor (a), said Michael donor (b) or said onium salt pendant group -containing polymer (c).

An exemplary method may comprise reacting (meth)acrylic acid in an amount stoichiometrically smaller than its epoxy equivalent in the preparation of the epoxy resin or epoxy 29 acrylate resin as said Michael acceptor (a) to leave some of the epoxy groups unreacted. An alternative method comprises copolymerizing glycidyl (meth)acrylate, J3 -methyIglycidy'l (meth)acrylate, 3,4-epoxycyclohexanemethanol (meth)acrylate or the like as a comonomer in the preparation of said Michael donor (b) or the onium. salt pendant group- containing polymer (c).

Said Michael acceptor (a), said Michael donor (b) or said onium salt pendant group-containing polymer (c) which is the product obtainable by appending epoxy compound is not particularly restricted but includes a, 0 -unsaturated carbonyl group/epoxy group - containing acrylic resin and active methylene grouplepoxy group- containing acrylic resin.

The 5-membered-ring carbonate compound mentioned above is not particularly restricted but includes 2-oxodioxolane (also known as ethylene carbonate) and its derivatives. Those compounds can be used each alone or in a combination of two or more species.

The 2-oxodioxolane and its derivatives mentioned above can be produced by reacting a 1, 2 -alkylene glycol in which two hydroxyl groups are attached to adjacent carbon atoms, e.g. ethylene glycol, 1,2- propylene glycol or 1,2-butylene glycol, with, for example, phosgene for cyclization.

As an alternative, glycerin may be reacted with phosgene for cyclization to give 2 - oxo - 4 - hydroxymethyldioxo lane (also known as glycerin carbonate). Any of those 5-membered-ring carbonate compounds can be used in an independent form as the cocatalyst (c-iii).

The glycerin carbonate mentioned above can be converted to a 5-membered-ring carbonate monomer by introducing a polymerizable unsaturated group by utilizing the residual hydroxyl function in the molecule. This is not an exclusive method, however. Thus, for example, the method using an etherification reaction with a polymerizable alcohol such as 35 allyl alcohol, 1-propenyl alcohol or the like, the method using the esterifIcation reaction with a reactive derivative of acrylic acid or methacrylic acid e.g. hallde, and the method using an addition reaction with methacryloyl isocyanate, among other methods, can be utilized.

The 5-membered-ring carbonate monomer can be polymerized withh suitable other monomer and the resulting polymer be used in independent composition as said cocatalyst (c-iii) or as a pendant compostion appended to saidMichael acceptor (a), said Michael donor (b) or said onium salt pendant group- containing polymer (c) by copolymerization reaction.

Thus, in the production of said Michael acceptor (a) or said Michael donor (b), which is derived f rom an acrylic polymer, or the onium salt pendant group-containing polymer (c), the 5-membered-ring carbonate monomer can be copolymerized so as to append the 5-membered-ring carbonate monomer pendant group to said Michael acceptor (a), said Michael donor (b) or said onium salt pendant group-containing polymer (c).

For example, when an active methylene group -containing acrylic monomer is copolymerized with an acrylic monomer, optionally together with a hydroxyl group -containing acrylic monomer andlor an ethylenically unsaturated group- containing monomer other than acrylic monomers, the 5-membered-ring carbonate monomer can also be copolymerized to provide said Michael donor (b) having the 5-membered-ring carbonate compound as a pendant compound.

From the standpoint of availability of the starting materials, glycerin carbonate is preferred when the 5- membered-ring carbonate compound to be used as an Independent component, while glycerin carbonate acrylate or glycerin carbonate methacrylate is preferred in the case where the carbonate monomer is copolymerized with other monomers.

As the epoxy compound and the 5-membered-ring carbonate compound, it is preferable to use a glycidyl compound, e.g. the glycidyl ether or glycidyl ester, the alicyclic epoxy compound, the a-olefin epoxide. the 1,2-alkylene carbonate, or the 31 glycerin carbonate.

In the curable resin composition of the present invention. for exhibiting sufficient curability, the relative amounts of said Michael acceptor (a) and said Michael donor (b) are preferably so controlled that the equivalent ratio of the a, 0 - unsaturated carbonyl group in said Michael acceptor (a) to the active methylene or active methine. group in said Michael donor (b) will be 2:1 to 1:2, preferably 1.5:1 to 1:1.5.

Furthermore, in the curable resin composition of the present invention, expressing sufficiently high curability and for avoiding untoward effects on film performance, said onium salt (c-ii) is preferably attached so that said onium salt (c- ii) pendant group will account for 0. 1 to 10. 0 equivalent % based on the sum equivalent of a, 0 -unsaturated carbonyl group in said Michael acceptor (a) and the active methylene or active methine group in said Michael donor (b). The more preferred proportion is 0.2 to 5.0 equivalent %.

Where said cocatalyst (c-iii) is required, the curable resin composition, for expressing sufficient curability and for avoiding untoward effects on film performance, it is preferable to include and/or append the cocatalyst (c-iii) in such a proportion of 0. 5 to 100 equivalent % based on the sum equivalent of the a, 0-unsaturated carbonyl group in said Michael acceptor (a) and the active methylene or active methine 25 group in said Michael donor (b). The more preferred proportion is 5.0 to 40 equivalent %.

The curable resin composition of the present invention can be used as a coating vehicle as well. Such coatings also fall within the scope of the present invention.

The coatings may contain pigments which are generally used. The pigment is not particularly restricted but includes iron oxide, lead oxide, carbon black, coal dust, titanium dioxide, talc, barium sulfate, cadmium yellow, cadmium red, chrome yellow, metallic pigments (e.g. alumInum flakes), organic pigments (e.g. phthalocyanine blue, sincassia red, 32 etc.), and pearl mica. Those pigments can be used each alone or in a combination of two or more species.

The solid content of the coating is 20 to 90 weight t, and by using a low molecular monomer or compound as said Michael acceptor (a), said Michael donor (b) or said cocatalyst (ciii), the solid content can be controlled to 80 to 90 weight % to thereby implement the super-hIgh-solid coating.

The solid content of the coating at application is preferably 10 to 80 weight %, more preferably 20 to 80 weight particularly 30 to 70 weight %, and more desirably 40 to 60 weight %.

There is no particular limitation on the method of preparing the coating. Thus, the formulating components described above can be admixed by means of asoil mixer. When the formulation includes the pigment mentioned above, these compounds may be kneaded by means of a kneader, a roll, or the like machine.

The coating can be applied onto a substrate by various coating techniques such as spray coating, brush coating, dip coating, electrostatic coating, roll coating, and f low coating.

The coating yields a cured film owing to crosslinking by Michael reaction at a baking temperature of 100 to 200t, preferably 120 to 1SO'C. The curing time, which depends upon curing temperature, is preferably within the range of 10 to 30 minutes at 120 to 150r,.

The coating containing the curable resin composition of the present invention as a vehicle can be used as a top clear coating.

The top clear coating usually does not contain a pigment but the pigment may be included in a proportion not adversely affecting the clarity of the film.

When the top clear coating is applied to an automotive outside panel, not only the scratch resistance but also the resistance to acidic rain, which is a problem in recent years, is definitely improved as compared with the outside panel 33 finished with the acrylic top clear coating which is cured by conventional melamine resin curing agent.

Furthermore, whereas the solid content of the conventional top clear car coating Is 45 to 60 weight the top clear coating of the present invention shows the superhigh-solid formulation of as high as 70 to 95 weight % of the solid content, preferably 80 to 90 weight %, thus cutting on the volatile of the solvent vapor.

The top clear coating of the present invention can be used in the multilayer coating process which comprises forming an undercoating layer on a substrate surface and, then, a base coating layer containing a color pigment and/or a brightening agent thereon, applying a top clear coating on a wet-on-wet basis, and heat-curing the coatings.

The substrate mentioned above is not particularly restricted but includes metals such as iron, copper, aluminum, tin. zinc, etc., inclusive of alloys and castings; glass; plastics; and plastic foams. The top clear coating can be used with advantage on plastic and metal subs trates,' particularly cationically electrocoatable metal articles. The metals mentioned above are particularly preferred that they are chemically treated with phosphate, chromate, or the like in advance.

The articles comprising the substrates are not particularly restricted but include a variety of motor vehicles such as automobiles, trucks. autobicycles, buses, etc., inclusive of their components.

The undercoating layer mentioned above can be f ormed, f or example, by electrodeposition or by electrodeposition plus intermediate coating.

The electrocoating layer can be f ormed by using a cationic or anionic electrodeposition coating but the cationic electrodeposition coating provides a superior film in terms of corrosion resistance. The cationic electrodeposition coating mentioned above is a thermosetting electrodeposition coating 34 of the negative electrode deposition type which contains a basic amino group -containing resin as the base resin and is solublized by neutralization with an acid. and the coating procedure is carried out by using the substrate as the negative electrode.

The basic amino group -containing resin mentioned above is not particularly restricted but includes the resin obtainable by adding a secondary amine to the epoxy group of a bisphenol type epoxy resin, to mention a preferred example.

The secondary amine mentioned above is not particularly restricted but includes primary amines blocked by ketimination using diethylenetriamine and the like.

The crosslinking agent for use In the cationic electrodepositIon coating is not particularly restricted but includes blocked polyisocyanates as blocked by an alcohol, phenol, oxime, lactam or the like blocking agent.

The cationic electrodeposition coating may be optionally supplemented with pigments, e.g. color pigments, extenders, corrosion-resistant pigments, etc., hydrophilic andlor hydrophobic solvents, and various additives. The formulating 20 amount of the pigments may be 5 to 150 parts by weight relative to 100 parts by weight of resin solids.

Usually. the electrodeposition layer is formed in a preferably 10 to 40 gm of post-bake dry thickness, more preferably 15 to 25 Um. Preferably, the usual chemical pretreatment is applied prior to electrodeposition.

The intermediate coating layer mentioned above is f ormed by applying an intermediate coating on the electrodeposition layer to hide defects in surface preparation, insure a high degree of surf ace smoothness af ter application of a top coating, and provide for chipping resistance. As such, this coating contains organic and/or inorganic color pigments and extenders.

The color pigment which can be contained in the intermediate coating is not particularly restricted but includes organic pigments such as azo chelate pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indigoid pigments, perinone pigments, perylene pigments, dioxane pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, etc.; inorganic pigments such as yellow lead, yellow iron oxide, red iron oxide, carbon black, titanium dioxide, etc.; and extenders such as calcium carbonate, barium sulfate, clay, talc, etc. Those color pigments can be used each alone or In a combination of two or more species. As a standard formulation, gray series intermediate coatings containing carbon black and titanium dioxide as main pigments are frequently used. However, the so-called color intermediate coatings containing various color pigments in suitable combinations according to the hiding power of top coatings can be employed.

The thermosetting resin to be incorporated in the intermediate coating is not particularly restricted but includes acrylic resin, polyester resin, alkyd resin, epoxy resin, urethane resin, and other film-forTning resins and any of those resins is used in combination with a curing agent such as amino resin and/or blocked isocyanate resin. From the standpoint of pigment dispersibility and workability, the combination of alkyd resin and/or polyester resin with amino resin is preferred. The solid content of the intermediate coating is 30 to 70 weight %, preferably 35 to 55 weight %. The solid content 25 at application is 10 to 60 weight %, preferably 20 to 50 weight %. The preferred coating method of the intermediate coating comprises applying the coating, by the electrostatic, air spray, or airless spray technique, on the heat-cured or uncured elect rodepos it ion layer. After application, the intermediate coating layer as such can be cured at a temperature of about 10Or- to 180t. Generally, the dry thickness of the intermediate layer thus formed is preferably 10 to 60 tl m, more preferably about 20 to 50 Um. If the dry thickness is less than 10 Um, the undercoating layer may not be successfully hidden. Conversely when the dry thickness exceeds 60 ttm, 36 troubles such as poping and sagging are liable to take place. The base coating containing the color pigments and/or brightening agent Is applied after formation of the undercoating layer (the electrodeposition layer or, if necessary, the Intermediate coating layer) on the condition that the undercoating layer is cured or uncured. According to the top coating tInt value, It is preferable to first apply a color base coating and then construct a f irst top coating layer. In this case, a second top layer can be applied by using a 10 brightening agent -containing base coating to provide a highly decorative multilayer film. The color pigments which can be used in the base coatings are not particularly restricted but include the same color pigments as mentioned for incorporation in the intermediate 15 coating. The thermosetting resin for incorporation of the base coatings is not particularly restricted but includes the thermosetting resins mentioned incorporation of in the intermediate coating. From the standpoint of pigment 20 dispersibility, workability and weather resistance, the combination of acrylic resin andlor polyester resin with amino resin is particularly preferred. The solid content of the base coatings is 15 to 60 weight %, preferably 20 to 55 weight %. The solid content at application 25 is 10 to 50 weight %, preferably 20 to 45 weight %. Both of the intermediate coating and the base coating are preferably of the solution type. Only provided that they are of the solution type, any of the organic solvent type, water-based type (aqueous solution type, water dispersion type, 30 emulsion type) and non-aqueous dispersion type can be freely selected. Furthermore, a curing catalyst, a surface conditioner. etc. can also be incorporated as necessary. When the base coating is water-based, the thermosetting resins specifically mentioned in US Patent No. 5151125 and US Patent No.5183504, among other literature, can be used as 37 binders. Particularly, the thermosetting resin obtainable by using an acrylic resin having acrylamide, hydroxyl and acidic groups in combination with a melamine resin as disclosed in US Patent No.5183504 is excellent in finished appearance and quality. In this case, f or insuring a high-quality cured f ilm, the base coating layer is preferably preheated at 60 to 10OcC for 2 to 10 minutes prior to application of the clear coating.

The base coating is preferably applied, for example by the electrostatic or air spray coating, on the electrodeposition layer or the intermediate coating layer. and after this application the base coating layer as such can be heat to be cured at a temperature of about 100 to 180t. The dry thickness of the base-coating layer thus constructed is preferably about 10 to 60 tim, more preferably about 20 to 50 Um, in most cases. If the dry thickness of this layer Is less than 10 Um, the undercoaing layermaynot be successfully hidden. On the other hand, when the dry thickness exceeds 60 11 m, troubles such as poping and sagging are liable to take place.

When the base coating layer is f ormed u!ing a color pigment andlor brightening agent -containing base coating material alone, a 2-coat 1-bake (2C1B) multilayer coating film can be f ormed by applying the base coating material in the f irst place and a top clear coating in the second place on a weton-wet basis and heating the resulting film to be cured.

When the base layer Is f ormed with the color base coating material and brightening agent -containing base coating and in case that the color base coating material alone is heat to be cured after Its application, a 3-coat 2-bake (3C2B) multilayer coating layer can be provided by applying the brightening agent-containing coating on the cured base coating layer, applying a top clear coating on a wet-on-wet basis, and heating the resulting f Ilm to be cured. On the other hand, in case that the color base layer as such is not heat to be cured, the objective multilayer film can be provided by applying the brightening agent -containing base coating material on the wet 38 base coating layer, applying a top clear coating on a wet-on-wet basis and heating the resulting f ilm to be cured. Thus, a 3-coat 1-bake (3C1B) multilayer film having more satisfactory' decorative effect can be provided by forming the color base layer, the brightening agent-containing base layer, and the clear top layer on a wet-on-wet basis and finally heating the resulting film to be cured.

The film provided by the clear top coating is used for insuring surface smoothness and other necessary qualities, and the top clear coating of the present invention is used f or the top clear coating material.

The top clear coating is preferably applied, for example by the electrostatic or air spray coating, on the uncured brightening agent -containing base coating layer, and the clear coat as such can be cured at a temperature of 100 to 200'C to provide a cured f ilm. If the curing temperature is below 10Or', no suf f icient cure will be obtained. If 200t is exceeded. the cured film will become too hard and brittle. Preferably by heating the f ilm at a temperature of 120 to 18tr,, a highly crosslinked cured film can be obtained.

The curing time required f or the clear coating varies with different curing temperatures but may properly be 10 to 30 minutes at 120 to 180t. The dry thickness of the clear top film varies with different intended uses but is preferably 10 to 80 ttm in many cases, more preferably about 15 to 60 tim. If the dry thickness is less than 10 tim, the undercoating layer will not be successfully hidden. On the other hand, if the dry thickness exceeds 60 Um, troubles such as poping and sagging are liable to occur in the coating process.

The coating of the present invention can be applied when the base coating is used for a solid coating. For example, the coating can be applied to a process for forming a multilayer coating film (2C2B) which comprises forming an undercoating layer on an automotive outside panel, applying a color pigment-containing solid coating, heating it to be cured, 39 applying a top clear coating on a dry-on-wet basis, and heating the film to be cured.

When the base f ilm is f ormed f rom only a color base coating material, a 2-coat 2-bake (2C2B) film can be provided by applying the color base coating, heating it to be cured, applying the top clear coating on a dryon-wet basis, and heating the film to be cured.

When the base coating layer is formed from a brightening agent containing base coating and a conventional clear coating, a 3-coat 2-bake (3C2B) multilayer film can be provided by applying the base coating and conventional clear coating on a wet-on-wet basis, heating the resulting coat to be cured, applying the top clear coating on a dry-on-wet basis, and heating it to be cured. As the conventional clear coating, any of the clear top coatings heretobefore in use can be used.

In any case, the outermost layer Is formed by the 1-coat 1-bake (1C1B) process.

Since the coated article as coated by the multilayer coating process using the coatings of the present invention is such that the outermost layer of the multilayer film has been formed from a top clear coating containing the curable resin composition of the present invention as the vehicle, the coated article has suf f icient weather resistance and other fundamental properties and features high scratch resistance and acid resistance in particular. Such coated articles also fall within the scope of the present invention.

EXAMPLES

The following examples are Intended to illustrate the present invention in further detail and should by no means construed as defining the scope of the present invention.

Examples of Synthesis-1 to 8 Active m thylene 9=uplepoxy arQup- contain 1 ng geryllc resins (b-1) tQ (b-5) and (b-7) - and-epoxy group and active methylene aroup-Contalnlng anrylin resin (b-kl A f our-necked f lask equipped with a decanter, condenser, stirring rod and drip funnel was charged with 360 weight parts of xylene, and after the temperature was increased to 110t, 5 a monomer-initlator mixture as shown in Table 1 was added dropwise over 3 hours and the reaction system was further incubated at 110r, for 0.5 hour. Then, with the temperature being maintained at 1109C, a mixture of t-butyl peroxyoctoate (2 weight parts) and xylene (40 weight parts) was added dropwise over 0.5 hour and the reaction mixture was further incubated at 1 10r, for 1. 5 hours. By the procedure, varnishes containing active methylene group/epoxy group -containing acrylic resins (b-1) to (b-5), and (b-7), and an epoxy group -containing acrylic resin or active methylene group- containing acrylic resin (b-6) with the GPC (gel permeation chromatography) number average molecular weight (Mn), active hydrogen equivalent, and epoxy equivalent values indicated in Table 1 were provided. The nonvolatile matter content of each varnish is shown in Table 1.

The synthesis of the varnishe containing active methylene group/epoxy group- containing acrylic resins (b-7) was carried out at the porimerization temperature of 120t in order to reduce the molecular weight thereof.

[Table 1]

Table 1 a of rsis 1 Ex of win 2 Fx of synthesis 3 Ex of r 4 Ex of sit 5 Ex of reie 6 Ex of " 7 Ex of rsim 8 a rc Active Active ---77tNr-e Active mothAwne nwthylene ytanc mwthyl W400nc Epoxy g Active mns v/epoxy growlepoxy "WIepoxy WOU XY VCp-y Wwc Acryllic mcdmcm. om Poxy v containkw v containinc V"P- c c ckrc grow- cmukw CW" berm gmp- iwn aerm resin Acrylic resin acrylic rsin acryk resin ACY6G resin resin resin (b-6) am-Aic resin (h- l) (b-2) (15-3) (h-4) (h-l;) fb-7) ethyl 2-(methacrYloYlOXY)QthYl 244 244 - 244 244 244 271 malonew 2- - - 214 - - - - (acatoacctoxy)cthta n-butylrnethactylate 20 100 50 78 94 249 76 Styrene 80 - 80 - - so 80 94 Grycidyimethacrylate so 56 56 - 101 - 200 M-100 - - 78 - - - o M-GMA - - 62 - Kaya ester-0 18 is 18 18 18 18 18 68 Nonvolatile matter content 49.4 49.4 -50.1 49.9 48.7 50.0 50.0 57.0 Number average rmiccuter Yweight (Mn) 5400 5300 j 4900 4300 45W 4500 4700 2000 Active hydrogen ecluvalent 200 200 00 200 200 1) 200 IRS Epoxy qtivelerTt 1002 1002 12002 1002 1002 561 0 400 42 In Table 1, the active hydrogen equivalent and epoxy equivalent values are the corresponding values on a solid basis; M-100 represents 3,4- epoxycyclohexylmethyl methacrylate(trade name; Daicel Chemical), and M- GMA represents 0 methy1glycidyl methacrylate (trade name; Daicel Chemical).

Examples of Synthesis-9 to 16 Acrylic resins containing active methylene group anti gnat-.elrnary ammonium salt pendant group (c-l) to (c-6) and (c-a). and acrylic resin conta:Lning quaternary ammonium salt pendant aroun (c-7) A f our-necked f lask equipped with a decanter, condenser, stirring rod and drip funnel was charged with 360 weight parts of butanol, and after the temperature was increased to 11OcC, a monomer-initiator mixture as shown in Table 2 was added dropwise over 3 hours and the reaction mixture was further incubated at 110t for 0.5 hour. Then, with the temperature being maintained at 110C, a mixture of t-butyl peroxyoctoate, (2 weight parts) and butanol (40 weight parts) was added dropwise over 0.5 hour and the reaction system was further incubated at 1 10t for 1. 5 hours. By the procedure, varnishes having acrylic resins containing active methylene group and quaternary ammonium salt pendant group (c-1) to (c-6) and (c-8), and a varnish having acrylic resin containing a quaternary ammonium salt pendant group (c-7) were provided. TheirGPC(gel permeation chromatography) number average molecular weight (Mn), active hydrogen equivalent and quaternary salt equivalent values are given in Table 2 and the nonvolatile matter content of each varnish is also shown in Table 2.

The synthesis of varnishe having acrylic resins containing active methylene group and quaternary ammonium salt pendant group (c-8) was carried out at the porimerization temperature of 120 t in order to reduce the molecular weight thereof.

[Table 2]

Table 2

Ex. Of W 9 a of ovtie 10 EA. of -v ti " 11 U of reie 12 Eir of weie 13 a of oeie 14 a of er woo U of reh 1 A A resin Acrylic resin Acrylic resin Acrm resin resin Acrylic resin Acrylic resin r,w"k4ng active conuining active containing act" containing active emu active co 0 icmtin Conitswing active thMnor nmthegmo mUvyhrwv n-othykncgmup mev mcthylenov containing mcthy$cne V and quatemary and ry and quaternary and qc and "tow mid quaternary ry arnift am quaternary AMMOniurn salt amfforjum sak amtnonkon ask wwr salt affiffienium sall. Ammonium sak prt gp affiff salt pendant group pendant group p v pen group pendent pen v 0 1 (c-l) (c-2) (C-31 (C-4) (c-G) (c-a) to-8) ethyl 2-(mthaory(ovioxy) ethyl 244 244 244 244 244 270 malonate 2-(acetoacctoxy) - - - - 244 - - ethyirnotheerylete rr-rmthacryl 41 26 34 39 56 54 309 141 Styrone 80 80 so 80 80 80 80 112 (methocryloyfoxy)ethy"methyi ammonium chloride 35 - - - - 48 (mothocryloyfoxy)ethyhriyl- - so 50 - anium dimethyl Phosphate (mathacryloyloxy)ethyttriniethyi- - - 42 - - :E amrmnium brornide (methacryismido)propyMniethyt- - - - 37 - arnmonium chloride Tetrabutylammonium seryllate - - - 22 Dimethylaminoethyt mothecrylate - - - 11 - Kaya ester-0 18 1B 18 18 is 18 18 68 Nonvolatile mr content 49.5 49.8 50.1 49.5 48.9 47.4 50.0 55.0 Number average molocu)ar weight (Mn) 2700 2800 2900 3000 2800 2600 2700 1900 Active hydrogen equvalervt 200 200 2Q0 200 200 200 0 255 Quaternary ammonium swit nt 2805 2805 28W 2805 2805 5610 5610 2805 44 In Table 2, the active hydrogen equivalent and quaternary salt equivalent are the values on a solid basis.

Example of Synthesis-17 a,ig-Unsaturated carbonyl grouplepoxy group-containing acrylic resin (a-U To introduce an a, J3 -unsaturated carbonyl group into the epoxy group- containing acrylic resin prepared in Example of Synthesis-6, 24 weight parts of methacrylic acid and 0. 1 weight part of hydroquinone were added to 400 weight parts (resin solids 200 weight parts) of the epoxy group- containing acrylic resin obtained in Example of Synthesis-6 and the reaction was carried out at 120t until an acid value of not greater than 1 had been obtained. By this procedure, a varnish having an a,J3-unsaturated carbonyl grouplepoxy group-containing acrylic resin (a- 1) with a double bond equivalent of 790 (on a solid basis) and an epoxy equivalent of 3300 (on a solid basis) was provided. The nonvolatile matter content of this varnish was 52.8%.

Example of Synthesis-18 Unsaturated polyeRtAr rAsin (a-21 A reactor was charged with 236 weight parts of 1,6hexanediol, 78 weight parts of dimethyl phthalate, 230 weight parts of dimethyl maleate, and 1 weight part of dibutyltin oxide. The temperature was increased to 1209C and, then, gradually to 200t while the methanol byproduced in the transesterif Ication reaction was constantly distilled off. Then, the temperature was f urther maintained at 20OcC until methanol was no longer distilled off, followed by cooling. Then, 250 weight parts of xylene was added. By this procedure, a varnish having an unsaturated polyester resin (a-2) with a GPC (gel permeation chromatography) number average molecular weight (Mn) value of about 1700 and a double bond equivalent value of 264 (on a solid basis) was provided. The nonvolatile matter content of this varnish was 61.4%.

Example of Synthesis-19 Active methylene group-contalnina polympr (h-8) A reactor was charged with 236 weight parts of 1,6- hexanediol, 264 weight parts of dimethyl malonate and 1 weight part of dibutyltin oxide and the temperature was increased to 1209C and further gradually to 2009C while the methanol byproduced in the transesterif ication reaction was constantly 10 distilled off. The reaction mixture was further maintained at 200r, until methanol was no longer distilled off. After cooling, 250 weight parts of xylene was added. By this procedure, a varnish having an active methylene groupcontaining polymer (b-8) with a GPC (gel permeation chromatography) number average molecular weight (Mn) value of about 1800 and an active hydrogen equivalent value of 91 (on a solid basis) was obtained. The nonvolatile matter content of this varnish was 58.8%.

Example of Synthesis-20 Active methylene group-contalning polymer (b-9) A reactor was charged with 144.1 weight parts of 1,4cicrohexanedlmethanol, 396.4 weight parts of dimethyl malonate and 0. 37 weight part of phosphoric acid and the temperature was increased to 1509C while nitrogen was injected and the temperature was further increased gradually to 180t while the methanol byproduced in the transesterification reaction was constantly distilled off. The reaction mixture was further maintained at 18OcC until methanol was no longer distilled of f.

After cooling, the excess dimethyl malonate was removed by reduced pressure from the reaction mixture. By this procedure, a varnish having anactive methylene group -containing polymer (b- 9) with a GPC (gel permeation chromatography) number average molecular weight (Mn) value of about 660 was obtained. The nonvolatile matter content of this varnish was 97%.

46 Example of Synthesis-21 Active methylene group -containing polymer (b-10) A reactor was charged with 240 weight parts of hydorgenated bisphenol A, 396.4 weight parts of dimethyl malonate and 0.44 weight part of phosphoric acid and the temperature was increased to 150t while nitrogen was injected and the temperature was further increased gradually to 170t while the methanol byproduced in the transesterification reaction was constantly distilled off. The reaction mixture was further maintained at 170t until methanol was no longer distilled of f. Af ter cooling, the excess dimethyl malonate was removed by reduced pressure from the reaction mixture. Bythis procedure, a varnish having an active methylene groupcontaining polymer (b-10) with a GPC (gel permeation chromatography) number average molecular weight (Mn) value of about 800 was obtained. The nonvolatile matter content of this varnish was 98%.

is Example of SynthesIs-22 ActiMe methylene group-containing polymer (b-111 A reactor was charged with 100.9 weight parts of 1,4cyclohexanedimethanol, 86.1 weight parts of hexahydrophthalate anhydride (HHPA), 52.1 weight part of 25 neopentylgrycol (NPG), 12 weight part of xylene, and 0. 2 4 weight of phosphoric acid and the temperature was increased to 210t and, under nitrogen atmosphere, the reaction mixture was heated and stirred for 2.5 hours while being dehydrated by decanter. The reaction was stopped at the acid value of 6.0. 30 After cooling to a room temperature, 396.4 weight parts of dimethyl malonate and 7.9 weight part of neopenthyl grycol (NPG) were added to the reaction mixture, and under nitrogen atmosphere, the temperature was increased to 150t and further gradually to 18OcC while the methanol byproduced in the transesterification reaction was constantly distilled off.

47 The reaction mixture was further maintained at 180r, unjL.-il methanol was no longer distilled of f Af ter cooling, the excess dimethyl malonate was removed by reduced pressure from the reaction mixture. By this procedure, a varnish having an active methylene group -containing polymer (b-11) with a GPC (gel permeation chromatography) number average molecular weight (Mn) value of about 900 was obtained. The nonvolatile matter content of this varnish was 86%.

Example of Synthesis-23 Active methylene group /quaternary ammonium salt pendant CroUP - containing polymer (c-9) A reactor was charged with 86.9 weight parts of active methylene group- containing polymer (b-10) synthesized in Example of Synthesis-21, 4.4 weight parts of (methacryloyloxy) ethyl triethylammonium chloride, 7.1 weight parts of hydorgenated bisphenol A, and 16.4 weight parts of n-buthanol and the temperature was increased to 100t while nitrogen was injected and the reaction mixture Was stirred for 3 hours. The reaction was terminated when it was comf irmed that C=C double bonds were diminished by nuclear magnetic resonance (NMR). By this procedure, a varnish having an active methylene grouplquaternary ammonium salt pendant group-containing polymer (b-9) was obtained. The nonvolatile matter content of this varnish was 82%.

Examples 1 to 5 To each of the resin formulations (weight parts) consisting of Michael acceptor (a), Michael donor (b), and onium.

salt pendant group -containing acrylic copolymer (c) as shown in Table 4 were added 10 weight parts of Tinuvin T-384 (trade name; Ciba-Geigy, ultraviolet absorber) and 5 weight parts of Sanol LS-440 (trade name; Ciba-Geigy; light stabilizer) with constant stirring in Disper to provide top clear coatings of the present invention. Those top clear coatings were adjusted 48 to a viscosity corresponding to 30 seconds/209C as determined with Ford Cup No. 4.

Electrodeposition of zinc phosphated 0.8 mm thick dull steel sheets was carried out with the cationic electrodeposition Power-Top PU-SO (trade name, Nippon Paint) in a dry thickness of about 25 Am and, then, air-sprayed with Orga P-2 Sealer (trade name; Nippon Paint) in a dry thickness of about 40 A m, followed by being cured at 140r, for 30 minutes. The coated test sheets were then air-spray coated with a high-solid metallic base coating of the formulation shown (in weight parts) in Table 3 in a dry thickness of about 16 tim and the solvent-base coated steel sheets were set for about 7 minutes. [Table 31 Table 3 The formulation of high-solid metallic based coatings (trade name; TOYO Aluminum) 10 Acrylic resin varnish 50 ymel 202 (trade name: Mitsui Cytech) 10 Cymel 2 Cymel 327 (trade name; Mitsui Cytech) 10 Cymel 3 EAlpaste716ON 7 Isopropyl lsopropylalcofiol In Table 3, Alpaste 716ON (trade name; Toyo Aluminum) is an aluminum flake paste with an aluminum flake content of 65 weight %; the acrylic resin varnish is a varnish with a nonvolatile matter content of 80%, a number average molecular weight (Mn) value of 1800, a hydroxyl value of 100 (on a solid basis) and an acid value of 30 (on a solid basis); Cymel 202 (trade name; Mitsui Cytech) is a melamine resin with a nonvolatile matter content of 80%; and Cymel 327 (trade name; Mitsui-Cytech) is a melamine resin with a nonvolatile matter content of 90%.

49 The solvent-base coated test sheets set as above were air-spray coated with a viscosity- adjusted top clear coating on a wet-on-wet basis in a dry film thickness of about "40 9 m. Af ter about 7 minutes' setting, the coat was heat to be cured at 120r, for 25 minutes to provide 2-coat 1bake (2C1B) coated test sheets.

The film performance of the coated sheets was evaluated by the methods described below. The results are shown in Table 4.

Evaluation Methods (1) Pencil hardness The pencil hardness was evaluated in accordance with JIS K5400 8.4.2.

(2) Appearance Af ter curing, the surf ace of the cured f ilm was visually evaluated according to the following criteria. 0: the surface gross is even and satisfactory. 0: the surface gross is slightly uneven.

X: there is no surface grossall over or the surface gross is uneven all over.

[ Table 41

Ln 1:11 X R! Table 4 Solvent-based coatings C H 0) 0 0 0 0 (D 0 rt 0 (D 0 (D 0 0 0 LI::11 0 9 0 F.A (D Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex 5 VACISCAJ acceptor PETA 50 50 50 50 50 (5) conent Active methylene group/epoxy group Wheal do (b) containing acrylic resin (b- 1) 405 405 405 405 - coent Active rnethylene group/epoxy gmp containing acrylic resin (b - 3) - - - 405 Acrylic resin containing active methylene group &M quaternary ammonium salt pendant Voup, 46 - - (c- 1) Acrylic resin containing active methylene V and Quaternary ammonium salt pendant grow - 32 - Acrylic resin (c-2) containing onium Acrylicresin containing active mothyienogp oak pendant group and Quaternary ammonium salt pendant grow - - 38 - (c) component (c-3) Acryficresin containing active mothyiencgmug and quaternary wnmonium "R pendant V - - 44 - ( -4) Acrylic resin containing active methylene group and quaternary ammonium salt pendant grow - - 32 Curing condition 120C.25min. 160C.25rnin. 120C.25nn. 1201C.25min. 160C25mh Pencil hardness H HB F F H Appearance 0 0 0 0 0 (n 0 51 weight parts) in Table 6 and a water-based metallic base coating of the f ormulatIon shown (in weight parts) in Table 5 in lieu of the high-solid metallic base coating, the procedure of Examples 1 to 5 was otherwise repeated to prepare and evaluate 5 test coated sheets. The results are shown in Table 5.

Table 5 The formulation of water-solid metallic based coatings Alpa'ste716ON (trade name: TOYO Aluminum) 10 Methyl-etherified melamine resin 30 lsostearyl phosphate 1 Water-based acrylic resin varnish 56 In Table 5, the methyl-etherified melamine resin is a resin with an imino content of 0.1 per triazine ring and a nonvolatile matter content of 100%; the water-Pased acrylic resin varnish is a varnish (nonvolatile matter 50%) containing an acrylamide- containing acrylic resin with a number average molecular weight (Mn) of 12000, a hydroxyl value of 70 (on a solid basis) and an acid value of 58 (on a solid basis) as obtained by copolymerizing 76 weight parts of ethylene glycol monobutyl ether, 15 weight parts of styrene, 63 weight parts of methyl methacrylate, 48 weight parts of 2-hydroxyethyl methacrylate, 117 weight parts of n-butyl acrylate, 27 weight parts of methacrylic acid, 30 weight parts of acrylamide, 3 weight parts of azobisisobutyronitrile, 28 weight parts of dimethylethanolamine and 200 weight parts of deionized water.

[ Table 61 (II Table 6 Water-based coatings -A F- C: 0 0 0 (D:2 (D (D 0 un PO r 0 (D 0 Pj (D 0 PA 0 it 0 (D (D 0 hh 0 0 P (D 0 rt w 0 (D P4 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Micheal acceptor PETA 50 so 50 50 50 (a) component Active methylene grouplepoxy group- containing 405 405 405 405 - Micheal donor acrylic resin (b- 1) (b) conwriont Active methylene group/epoxy group- containing acryllic resin (b-3) - - - - 405 Acrylic resin containing active mathylens group and "temary ammonium salt pendent group 46 - - (0-11 Acrylic resin containing active methylene group Acrylic resin and quaternary ammonium salt pendant group - 32 - containing onium Acrylic resin containing active methylene group salt pendent and quaternairy ammonium sAt pendant v - - 38 - group (c) (c-3) component Acrylic resin containing active rnetWne group and quaternary ammonium saft pMant group - 44 - (C-4) AerMY1IC resin containing active methylene group and quaternary ammonium salt pendent group - - 32 (C-5) Curing condition 130C.25min. 160C.25mim 130C,25min. 1309C,25mh 160C,25"L Pencil hardness F HB HB HB H Appearance 0 0 a 0 0 (n m Table 7 Solvent-based coadngs Ey- 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Micheal acceptor P,ETA 50 50 50 50 so (0) component Active methylene group/apoxy group- containing 405 405 - acrylic resin (b-2) Active moene grouplepoxy grouip- containing - - 405 Micheal donor acrylic resin (b-3) (b) COMPOnnt Active methylene grouplapoxy group- containing - - 405 - acrylic resin (b-4) Active methylene grouplapoxy v-caidnc - - 405 acrylic resin (b-5) Acrylic resin containing active methylene grcup and tomwy ammonium salt pendant group 46 Acrylic resin containing active methylene group and quaternary ammonium salt pendant group - 32 - Acrylic resin (c-2) containing Onium Acrylic resin containing active methylene group &aft pendant and quatwrnary ammonium saft pendant group - - 32 - gp (c) (c-3) component Acrylic resin containing active methylene group and quaternary ammonium &At pendant r - 46 - (c-4) ic resin containing active methylene group quaternary ammonium saft pendant group - - 46 (c-5) Curing condition 120C. 25mfn. 160t. 25mim 120t. 25mh 140t. 25min. 160C. 25min.

Pencil hardness H HB F HB H B Appearance 1 0 0 (D 0 #-g c (D 4 to:v (D (D rl, W ::r (D m (D M c:

-A rt rn 9 (D ld tl 0 0) (D:j rt (D a :2 h3 p cr bi 0 4 (n W 54 Examples 16 to 20 Using resin components according to the formulations shown in Table 8 (weight parts), the procedure of Examples 6 to 10 was otherwise repeated to prepare and evaluate test coated 5 sheets. The results are presented In Table 8.

[ Table 81 (n r U) C1 0 r X 0 Table 8

*9 Water-based coating FJ6 C:

0 (D 0 (D 0 (D W rt, P) 0 0 Fi. 0 Pi 0 rt 0 pI r rt F.A P1:]m (D (D 0 (D 0 rn 0 p) (D 0 rt. 0 (D m Ex. 16 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Micheal acceptor PETA 50 so 50 so so (2) component Active methylene grouplepoxy group-containling 405 405 - acrylic resin (b-2) Active M VOUP/OPOXY - 405 - Micheal donor acrylic resin (b-3) (b) connnt Mtive mene grouplepoxy group int - 405 - acrylic resin (b-4) Active methylene grepoxy "U"Ontakong - - 405 acrylic resin (b-5) Acrylic resin Acrylic rosin containing active methylene group containing onium &M quetwy" ammonium it pendent group 46 - 46 46 (0-1) saft pendant group (c) Acrylic resin containing active Methylene group and quaternary ammonium &aft pendant grow - 32 32 - component (c-2) Curing condition 130t, 25mim'160C. 25min. IWC. 25min. 1401C. 25min. UTC, 25min.

Pencil hardness F HB H HB HS Appearance 0 0 0 i 0- 0 0 QI Un H 0 1-3 0) lw, i-i (1) X0 (D (D M (D 0 C-1, m h.& EI (D rt r k14 l_ 0 1,_i V0 tl 0 Tabts 9 S cb d tin Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 TIVIPTA 50 50 50 - Mkheal acceptor DPCA- 120 - - - 150 - (a) component 95 LIA- 306H Micheal donor Active metwens p/epoxy group-containint 405 405 405 405 400551 (b) component acrylic resin (b-1) Acrylic resin containing active methylene group 46 46 and quaternary ammnium sit pendent group 46 - Acryllic resin (c- 1) COMAining OniUm Acrylicresin ci-ntaining active mothylencroup salt pendent and quaternary ammonium salt pendant group - 32 - - - (c) (c-2) group Acryk resin containing active metWone Voup - 38 - component and quaternary ammonium sidt pendent group (c-3) Curing condition 12 0 f-'. 25min. 1 60C. 25min. 1200C. 25min. 120C. 25am 120 '5 j 1H Pencil hardness H HB H F Appearance 0 - 0 cr (D (D l_:i 1.9 0) cr (D m (n 0 57 triacrylate; DPCA-120 is KAYARAD DPCA-120 (trade name; Nippon Kayaku; dipentaerythritol (1 mole) - caprolac tone (12 mole) ring-opening adduct hexaacrylate); and UA-306H is UA-306H (trade name; Kyoeisha Yushi Kagaku Kogyo; hexamethylene diisocyanate (1 mole)-pentaerythritol triacrylate (2 moles) adduct).

Examples 26 to 30 Using resin components according to the formulations shown in Table 10 (weight parts), the procedure of Examples 6 to 10 was otherwise repeated to prepare and evaluate test coated sheets. The results are presented in Table 10.

[Table 101 (.n rt M C1 0 r UI 0 0 W (D (D:2 W 0 0 (D 0 h 0 (D 0 0 0 CD (D re 0 m 0 0 p) (D 0 Table 10 Water-based coatinas Ex. 26 Ex. 2 7 Ex. 2 8 Ex. 29 Ex- 30 TNIPTA so so so - - Micheal acceptor OPCA- 120 1 (a) component UA-306H - - - - 95 hficheal donor Active methylene group/opoxy group-containing 405 405 405 405 405 (h) component acryrec resin (b- 1) Acryticresin containing active rmthyioncr Acrylic resin and torn" ammonium saft pendant group 46 - - 46 46 (0-1) containing ONUM Acrylicratin containing active methylanogroup aft pendent and quatemary ammonium salt pendent group - 32 - - - group (c) (c-2) component Acrylic resin containing active methylene grouo and tanwry ammonium talt pendant c - 38 (c-3) Curing condNon UTC. 25mh 16. 25min. 130C. 25mh 1130Q 25min. 130'M 25min.

Pencil hardness H HB H HB F Appearance 0 0 0 0 - - - 0 (n 0 (_n P' " m 0 r Solvent-based coatings (D m 0) H PC:3 0 F- h 0 w 0 0 kD P PC rh (D h rt W4 0 0 (D V 0 (D M" rt 0 m m P) P, 0 0 9 0 1.

Table 11

Ex._ 31 Ex. 3 2 A-400 200 Micheat acceptor (a) component Acrylic resin containing a. #-unsaturated - 379 carbonyl group and-epoxy group (a-1) Active methylene group/epoxy group- containing 405 - Micheal donor acrylic resin (b-3) (b) component DTIVIPTA - 25 Acrylic resin Acrylic resin containing active methylene group - 46 containing onium and quaternary ammonium salt pendant group (c-l) salt pendant Acrylic resin containing active methylene group group (c) and quaternary ammonium salt pendant group 32 component (c-4) Curing condition 12TC, 25min. 11200C. 25min.

Pencil hardness HB H E3 Appearance -3 P) c 0 $-A -4 0 r 0 0 rt 0 h_3 0 M (D 0 0 -i rt m p) m 0 m (D 0 (D 0 rt 0 a 0 b_3 0) a, -1 (D ba bi Examples 33 and 34 Using resin components according to the formulations shown In Table 12 (weight parts), the procedure of Examples 6 to 10 was otherwise repeated to prepare and evaluate test coated sheets. The results are presented in Table 12.

[Table 121

J2 L 0.5 J2 E CV) C> in Tr W CO E In C9 CM >i C\& Cl W E.

E 0 0 E:; A r 0 E CL E E c 00 2. 0 c 4, 9 ID 0 0 he U CL C OL Ire 0 < < 0 0 E 52 0 2 0 2 61 Example 35 to 41 Using resin components according to the formulations shown in Table 13 (weight parts), the procedure of Examples 1 to 5 was otherwise repeated to prepare and evaluate test coated 5 sheets. The results are presented in Table 13..

[Table 131

1 Table 13 Solvent-based coatings Ex. 35 Ex. 36 Ex. 37 Ex. 38 Ex. 39 Ex. 40 Ex. 41 Acrylic resin containing a. $-unsaturated 379 379 - 379 carbwM group end epoxy group (&-1) Mich,a, acceptor Unsaturated polyester resin (a-2) - - - - (a) component PETA 150 80 40 40 X-22-164B - - - 40 DTIVIPTA 70 70 - Active methylene grouplepoxy uuup- 405 - - containing scryllc resin (b-1) Active methylene group/epoxy group- - - 35 35 ciningacrylic resin (b-7) Micheal donor Active methylene group-containing polymer 340 - - (b) component (b-8) Active methylene group-containing polymer - 30 (b-10) Active mothylene group-containing polymer 60 - (b-11) MACRYNAL LH437 127 - Acrylicrsin containing active mothylenegroup and quaternary ammonium salt nt group 46 46 46 46 (C-l) Acrylicresin containing active mothylonagroup Acrylic main and quaternary ammonium satt par Croup - 38 - containing oneurn (c- 2) A"lic resin containing ective methylene group salt pendant and quaternary ammonium oak pendant group - 36 group (c) (c-$) component Polymer containing active methylene group and quaternary awm saft pendant group 49 (c-9) Epoxyhexadecane 30 - - Curing condition 12M. 25min. 150C. 25min. 120'C, 25min. 120C. 25mirt 120%. 25mh 1409C. 25mh 140t. 2Sodn.

Pencil condition HB HB F F HB HS HE3 Appearance 0) 0 0 0 0 0 0 (h h) 63 In Table 13, X-22-164B represents X-22-164B (trade name; Shin-Etsu Chemical; a polysiloxane having a 3methacryloyloxypropyl group at either terminal end) and MACRYNAL LH437 represents MACRYNAL LH437 (trade name; Hoechst; a polyfunctional methanetricarboxylic ester).

Examples 42 to 48 Using resin components according to the formulations shown in Table 14 (weight parts), the procedure of Examples 6 to 10 was otherwise repeated to prepare and evaluate test coated sheets. The results are presented in Table 14.

[Table 14]

Table 14 Water-based coatings Ex. 42 Ex. 43 Ex. 44 Ex. 45 a 46 a 47 Ex. 48 Acrylic resin conitaining or. fl - untturated 379 379 - - 379 - - carbonyl group and CPOXY group (-l) Kr,h681 ace ptor Unsaturated polyester resin (a-2) - - - - - - - (a) compo= PETA 150 80 54.4 44.7 X-22-164B - - - 40 - DTMPTA 70 j) - 77(0 Active methylone group/epoxy group- containing - 405 - - acrylic resin (b- 1) Active methylene grouPlepoxY groupContailding aic resin (b-7) - - - 35 35 Micheal donor (b) Active methylene group- containing acrylic retin - 340 - - (b-e) component Active Yiene group-containint polymer (b-9) - 60 - Active methylene group- containing acrylic resin (b-10) 60 MACRYNAL LH437 - - - 127 - Acrilicresin containing active nwthyfenerovp and "to ammonium omit pendent group 46 46 46 46 Acrylic resin (0-1) Containing ontum Acrylic resin containing active methylene group salt pendent and quaternary arntnoniwn &aft pendant group - 38 - - - - - (c-2) group (c) Acrylic resin contakMg methylene group component and quatommy ammnium salt pendant groo - 36 36 (c-a) Epoxyhexadecam 30 - - Curint condition 130C, 25mh 160C. 25min. 1306C. 25min. 1130C. 25min. IZITC. 25min. 14CC, 25min, 140C. 25mh Pencil hardness HB F F F F F-H F-H Appearance 0 0 0 0 0 0 Examples 49 to 51 Using resin components according to the formulations shown in Table 15 (weight parts), the procedure of Examples 1 to 5 was otherwise repeated to prepare and evaluate test coated 5 sheets. The results are presented in Table 15.

[Table 151

Ld E CL cr c Examples 52 to 54 Using resin components according to the formulations shown in Table 16 (weight parts), the procedure of Examples 6 (11 0 C: 13) cr m cj -4 (D 0 C0 F- -9 un 10 r 0 rt. W (D 0 0 0 rt r (D 0 m 0 0 b n 0 Table 16

Water-based coatings Ex. 52 Ex. 53 Ex. 54 Wcheal acceptor PETA 50 50 50 (a) component Active methylene vPoxy group- containing - - 405 Micheal donor acrylic resin (b-1) (b) component Active methylene group-containing acrylic resin 400 400 - (b-6) AeMic: resin Acrylic resin containing active methylene group containing oniurn and quaternary ammonium salt pendant g 33 - 33 salt pendent (c-c) group (0) Acrylic resin containing tortUuy smin pendant - 32 - component group (c-7) Curing condition 130Q 25mh Wrni 130 600C. n.

Pencil hardness H B H Appearance 1 0 0 0 #.3 0 cr J_ 0 1,_h Ch 0 rt :r 0 0 0 :r rt (D 0 0 CD Ch -, m:2 (D cr 0 cc 0 03 rt, (D P4 67 to 5 was otherwise repeated to prepare and evaluate test coated sheets. The results are presented in Table 17.

[Table 171 j Table 17

Solvent-based coatings Compar. Ex.1 Compar. Ex.2 Compar. Ex.3 Compar. Ex.4 Micheal acceptor PETA 50 50 50 50 (a) component Active methylene group/epoxy group- containing 405 405 405 - Micheal donor acrylic resin (b-1) (b) component Active methylene group/epoxy group- containing - - 405 acrylic resin (b-3) Acrylic resin TBACI 2 - 2 containing onium salt pendant TMBP - 2 - - (c) group component TBABr - 2 Curing condition 120Q 25min. 1209C, 25min.120Q 25min. 120C, 25min.

Pencil hardness 213 313 2B 213 Appearance X X X X 69 In Table 17, TBAC1 represents tetrabutylammonium chloride; TMBP represents trimethylbenzylammonium dibutyl phosphate; and TBABr represents tetrabutylammonium bromide.

Comparative Examples 5 to 8 Using resin components according to the formulations shown in Table 18 (weight parts), the procedure of Examples 6 to 10 was otherwise repeated to prepare and evaluate test coated sheets. The results are presented in Table 18.

[Table 181

1 cr (D h& 0 (a 0 cr 0 o 0 0 0 0 0 0 () 0 01 (D re 0 Table 18

Water-tased coatings Compar. E" Compar. Ex.6 Compar. Ex.7 Comper. Ex.8 Micheal acceptor PETA 50 50 50 50 (8) component Active methylene grouplepoxy p- containing 405 405 405 - Micheal donor semicresin (b-1) (b) component Active methylene giroup/opoxygmupr-contiining acrylic resin (b-3) - - - 405 Acrylic resin TBACI 2 - 2 containing onium salt pendent TMSP - 2 - - (c) group component TBABr - 2 Curing condition 130Q 25min. 130C. 25min. UCC, 25min. 130C. 25mh Pencil hardness uncured uncured uncured uncured Appearance X X X X 4 0 71 solid f eature while upholding fundamental characteristics such as scratch resistance and acid resistance and eliminates the trouble of defective curing due to diffusion of a Michael reaction catalyst into the base coat.

The multIlayer film forming method of the present invention provides a composite f ilm having an attractive appearance as well as satisfactory functional characteristics.

The coated article according to the present invention has an excellent appearance and satisfactory coating film characteristics.

72

Claims (11)

1. A curable resin composition either comprising a Michael acceptor (a) and a Michael donor (b) or comprising said Michael acceptor (a), said Michael donor (b) and an onlum salt pendant group-containing polymer (c), wherein said Michael acceptor (a) comprises an a,,6 -unsaturated carbonyl group- containing compound and/or an a, 0 -unsaturated carbonyl group-containing polymer, said Michael donor (b) comprises an active methylene or active methine group-containing compound andlor an active methylene or active methine group-containing polymer, and said onium salt pendant group -containing polymer (c) is a product obtainable by appending an onium salt (c-11) to an acrylic polymer (c-i) or a product obtainable by appending said onium salt (c-ii) to an active methylene or active methine group-containing polymer by Michael addition reaction, in the case that the composition comprises said Michael acceptor (a) and said Michael donor (b), at leasit one of said Michael acceptor (a) and said Michael donor (b) is a product obtainable by appending said onium sait (c-ii), and said onium salt (c-ii) is at least one compound selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, tertiary sulfonium salts and tertiary amines.

2. The curable resin composition according to Claim 1 wherein said Michael acceptor (a) is at least one selected from the group consisting of polyhydric alcohol (meth) acrylic esters, polyester acrylate resins, unsaturated polyester resins, fatty acid- containing polyesters, oils and fats, epoxy acrylate resins, urethane acrylate resins, a, J3 -unsaturated carbonyl group- containing acrylic resins, polyether acrylate resins and (meth)acryloyl group-containing silicone oligomers.

73

3. The curable resin composition according to Claim 1 or 2 wherein said Michael donor (b) is at least one selected from the group consisting of transesterification products between a polyhydric alcohol or polyol and an active methylene group -containing carboxylic ester, esterif ication products of a polyhydric alcohol or polyol with an active methylene groupcontaining carboxylic acid compound, reaction products of a polyamine compound with a diketene, active methylene group -containing acrylic resins, and adducts of an isocyanate compound with an active methylene group- containing compound.

4. The curable resin composition according to Claim 1 or 2 wherein said Michael donor (b) being the product obtainable by appending said onium salt (c-ii) is an active methylene group -containing acrylic resin having a pendant group derived from at least one monomer selected from the group consisting of tertiary aminoalkyl (meth)acrylate, quaternized aminoalkyl (meth)acrylate, quaternized aminoalkyl(meth)acrylamide, quaternary ammonium (meth) acrylate, quaternary phosphinoalkyl (meth)acrylate, and quaternary phosphonium (meth)acrylate.

5. The curable resin composition according to Claim 1, 2, 3, or 4 wherein, in the case of the composition comprising said Michael acceptor (a) and said Michael donor (b), the composition further comprises a cocatalyst (c-iii) as an independent component, andlor, at least one of said Michael acceptor (a) and said Michael donor (b) is the product obtainable by appending by said cocatalyst (c-iii), in the case of the composition comprising said Michael acceptor (a), said Michael donor (b) and said onium salt pendant group-containing polymer (c), the composition further comprises the cocatalyst (c-iii) as an independent component, and/or, at least one of said Michael acceptor (a), said Michael donor (b) and said onium salt 74 pendant group -containing polymer (c) is the product obtainable by appending said cocatalyst (c-iii), the cocatalyst (c-iii) is at least one selected from the group consisting of epoxy compounds and 5-membered-ring 5 carbonate compounds.

6. The curable resin composition according to Claim 6 wherein the epoxy compound and 5-membered-ring carbonate compound is a glycidyl compound, an alicyclic epoxy compound, an a - olef in epoxide, a 1, 2 - alkylene carbonate, or a glycerin carbonate.

7. A coating which comprises a curable resin composition according to Claim 1, 2, 3, 4, 5 or 6 as a vehicle.

8. A method of forming a multilayer coating film which comprises forming an undercoating layer on a substrate, applying a color pigment andlor brightening agent -containing base coating, applying a top clear coating on a wet-on-wet basis.

and heating the resulting coat to be cured, wherein said top clear coating is the coating according to Claim 7.

9. A method of forming a multilayer coating f ilm which comprises forming an undercoating layer on a substrate, either applying a color pigment -containing solid coating and heating the resulting coat to be cured or applying a base coating and a clear coating on a wet-on-wet basis and heating the the resulting coat to be cured, thereafter applying a top clear coating on a dry-on-wet basis, and heating the resulting coat to be cured, wherein said top clear coating is the coating according to Claim 7.

10. A multilayer- coated article whose multilayer coat has an outermost layer formed from the coating according to Claim 7.

11. A curable resin composition substantially as hereinbefore described with reference to the Examples.