Curable film-forming compositions containing hydroxyl functional, branched acrylic polymers and multilayer composite coatings

A multi-component composite coating composition comprising a first film-forming composition applied to a substrate to form a colored base coat, and a second, transparent film-forming composition applied on top of the base coat to form a clear top coat, wherein the transparent film-forming composition comprises a curable film-forming composition comprising:

• (a) a polymeric binder comprising repeating ester groups in the polymer backbone and further comprising a plurality of carbamate groups of the structure:
• (b) a curing agent comprising functional groups that are reactive with the carbamate functional groups of (a);
• and
• (c) a reaction product of:
• (1) a hydroxyl functional (meth)acrylic polymer comprising the reaction product of:
• (i) at least 1 percent by weight of a (meth)acrylic monomer comprising at least two ethylenically unsaturated double bonds;
• (ii) at least 10 percent by weight of a (meth)acrylic monomer comprising a carbon atom that is bonded to four moieties wherein one of said moieties is a hydrogen atom and the remainder of said moieties comprises an alkyl group, wherein at least one of the alkyl group-containing moieties comprises an ethylenically unsaturated double bond;
• and
• (iii) at least one ethylenically unsaturated monomer that is polymerizable with (i) and (ii);
• wherein each monomer (i), (ii), and (iii) is different and wherein the monomer (i), (ii) and/or (iii) contains a hydroxyl functional group;
• and
• (2) a lactone or lactam;
• wherein the reaction product (c) has a weight average molecular weight of at least 500 to 8504.

A method for forming a composite coating on a substrate comprising:

• (A) applying a first film-forming composition to at least a portion of a surface of the substrate to form a colored base coat;
• (B) applying a second, transparent film-forming composition to at least a portion of the base coat formed in step (A) prior to curing the first film-forming composition, to form a clear top coat thereon, wherein the transparent film-forming composition comprises a curable film-forming composition comprising:
• (a) a polymeric binder comprising repeating ester groups in the polymer backbone and further comprising a plurality of carbamate groups of the structure:
• (b) a curing agent comprising functional groups that are reactive with the carbamate functional groups of (a);
• and
• (c) a reaction product of:
• (1) a hydroxyl functional (meth)acrylic polymer comprising the reaction product of:
• (i) at least 1 percent by weight of a (meth)acrylic monomer comprising at least two ethylenically unsaturated double bonds;
• (ii) at least 10 percent by weight of a (meth)acrylic monomer comprising a carbon atom that is bonded to four moieties wherein one of said moieties is a hydrogen atom and the remainder of said moieties comprises an alkyl group, wherein at least one of the alkyl group-containing moieties comprises an ethylenically unsaturated double bond;
• and
• (iii) at least one ethylenically unsaturated monomer that is polymerizable with (i) and (ii);
• wherein each monomer (i), (ii), and (iii) is different and wherein the monomer (i), (ii) and/or (iii) contains a hydroxyl functional group;
• and
• (2) a lactone or lactam;
• wherein the reaction product (c) has a weight average molecular weight of at least 500 to 8504;
• and
• (C) holding the substrate at a temperature and for a time sufficient to cure the composite coating after all coating layers have been applied to the substrate.