Composition with latent reactive catalyst-#4

A liquid, thermosetting high solids coating composition which (i) cures, at least in part, by reaction between an amine-aldehyde compound and hydroxyl functionality some of which is present on a film forming component prior to curing and some of which is generated in situ during cure of said composition, (ii) is adapted for low temperature bake applications, (iii) contains greater than about 55% by weight of nonvolatile solids, and (iv) exclusive of pigments, solvents and other nonreactive components, consists essentially of:

• (A) bifunctional film-forming copolymer bearing hydroxyl functionality and pendent epoxy functionality, having a number average molecular weight (M.sub.n) of between about 1,500 and about 10,000 and a glass transition temperature (T.sub.g) of between about -25.degree. C. and about 70.degree. C., said copolymer consisting essentially of (i) between about 5 and about 25 weight percent of monoethylenically unsaturated monomers bearing glycidyl functionality and between about 5 and about 25 weight percent of monoethylenically unsaturated monomers bearing hydroxyl functionality, with the total of said glycidyl and hydroxy functional monomers being not greater than about 30 weight percent of monomers in said bifunctional copolymer and (ii) between about 90 and about 70 weight percent of other monoethylenically unsaturated monomers;
• (B) a latent reactive catalyst comprising the reaction product of (i) a bifunctional copolymer bearing hydroxyl functionality and pendent epoxy functionality, having a number average molecular weight (M.sub.n) of between about 1,500 and about 10,000 and a glass transition temperature (T.sub.g) of between about -25.degree. C. and about 70.degree. C., said copolymer being prepared from (a) between about 1 and 25 weight percent of monoethylenically unsaturated monomers bearing glycidyl functionality (b) between about 10 and about 29 weight percent of monoethylenically unsaturated monomers bearing hydroxyl functionality, and (c) between about 65 and about 89 weight percent of other monoethylenically unsaturated monomers;
• and (ii) a sulfonic acid having the formula:
• ##STR5## wherein R is selected from linear or branched alkyl groups and aryl groups, said bifunctional copolymer bearing pendent epoxy functionality and said sulfonic acid being reacted in such amounts that there are between 0.3 and about 1 acid groups per epoxy in the reaction mixture;
• (C) an amine-aldehyde crosslinking agent;
• and
• (D) up to about 45 weight percent of a hydroxy functional additive having a number average molecular weight (M.sub.n) of between about 150 and about 6,000,
• said latent reactive catalyst being included in said composition in an amount ranging from about 0.5 to about 5 weight percent, said amine-aldehyde crosslinking agent being included in said composition in an amount ranging from about 15 to about 45 weight percent, said weight percents being based on the total weight of (A), (B), (C) and (D).

A liquid, thermosetting high solids coating composition which (i) cures, at least in part, by reaction between an amine-aldehyde compound and hydroxyl functionality on a film-forming component, which hydroxyl functionality is generated in situ during cure of said composition, (ii) is adapted for low temperature bake applications, (iii) contains greater than about 55% by weight of nonvolatile solids, and (iv) exclusive of pigments, solvents and other nonreactive components, consists essentially of:

• (A) a polyepoxide film-forming resin having a number average molecular weight (M.sub.n) of between about 140 and about 3,000;
• (B) a latent reactive catalyst comprising the reaction product of (i) a bifunctional copolymer bearing hydroxyl functionality and pendent epoxy functionality, having a number average molecular weight (M.sub.n) of between about 1,500 and about 10,000 and a glass transition temperature (T.sub.g) of between about -25.degree. C. and about 70.degree. C., said copolymer being prepared from (a) between about 1 and about 25 weight percent of monoethylenically unsaturated monomers bearing glycidyl functionality, (b) between about 10 and about 29 weight percent of monoethylenically unsaturated monomers bearing hydroxyl functionality, and
• (c) between about 65 and about 89 weight percent of other monoethylenically unsaturated monomers;
• and (ii) a sulfonic acid having the formula:
• ##STR6## wherein R is selected from linear or branched alkyl groups and aryl groups, said bifunctional copolymer bearing pendent epoxy functionality and said sulfonic acid being reacted in such amounts that there are between 0.3 and about 1 acid groups per epoxy in the reaction mixture;
• (C) an amine-aldehyde crosslinking agent;
• and
• (D) up to about 45 weight percent of a hydroxy functional additive having a number average molecular weight (M.sub.n) of between about 150 and about 6,000,
• said latent reactive catalyst being included in said composition in an amount ranging from about 1 to about 5 weight percent, and said amine-aldehyde resin crosslinking agent being included in said composition in an amount ranging from about 15 to about 45 weight percent, said weight percents being based on the total weight of (A), (B), (C) and (D).