Film-forming compositions having improved scratch resistance

A multi-component composite coating composition comprising a base coat deposited from a pigmented film-forming composition and a transparent top coat applied over the base coat in which the transparent top coat is deposited from a film-forming composition comprising:

• (a) 2 to 90 weight percent based on weight of total resin solids of an ungelled organic polysiloxane having hydroxyl functional groups, said polysiloxane comprising at least one unit of the following structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X′ is a hydroxyl functional group-containing organic polyvalent linking group selected from the group consisting of alkylene, oxyalkylene, and alkylene aryl, and is derived from a hydroxyl group-containing polyallyl ether capable of undergoing hydrosilylation reaction, said polysiloxane having an OH equivalent weight of 50 to 500 grams per equivalent;
• and n has a value ranging from 2 to 4 such that n is equal to the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• (b) 2 to 80 weight percent based on weight of total resin solids of an acrylic polyol having an OH equivalent weight of 100 to 1000 grams per equivalent;
• and
• (c) 2 to 60 weight percent based on weight of total resin solids of an aminoplast-curing agent.

A multi-component composite coating composition comprising a base coat deposited from a pigmented film-forming composition and a transparent top coat applied over the base coat in which the transparent top coat is deposited from a film-forming composition comprising:

• (a) 2 to 90 weight percent based on weight of total resin solids of an ungelled organic polysiloxane having carbamate functional groups, said polysiloxane comprising at least one unit of the following structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X″ is a carbamate functional group-containing organic polyvalent linking group selected from the group consisting of alkylene, oxyalkylene, and alkylene aryl, and is derived from a hydroxyl group-containing polyallyl ether capable of undergoing hydrosilylation reaction;
• and n has a value ranging from 2 to 4 such that n equals the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• (b) 2 to 80 weight percent based on weight of total resin solids of an acrylic polyol having an OH equivalent weight of 100 to 1000 grams per equivalent;
• and
• (c) 2 to 60 weight percent based on weight of total resin solids of an aminoplast-curing agent.

A process for applying a multi-component composite coating to a substrate comprising the following steps:

• (a) applying to a substrate a pigmented film-forming composition from which a base coat is deposited onto the substrate;
• and
• (b) applying onto the base coat a film-forming composition from which a transparent top coat is deposited over the base coat, said film-forming composition comprising:
• (i) an ungelled organic polysiloxane having reactive functional groups, said polysiloxane comprising at least one unit of the following structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X is an organic polyvalent linking group which optionally contains one or more reactive functional groups, wherein the polyvalent linking group is selected from the group consisting of alkylene, oxyalkylene, and alkylene aryl, and X is derived from a material having two or more unsaturated bonds capable of undergoing hydrosilylation reaction;
• and n has a value ranging from 2 to 4 such that n is equal to the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• and
• (ii) a curing agent having functional groups reactive with the functional groups of (i).

A multi-component composite coating composition comprising a base coat deposited from a pigmented film-forming composition, a first transparent top coat applied over the base coat in which the transparent top coat is deposited from a first film-forming composition, and a second transparent top coat applied over the first transparent top coat in which the second transparent top coat is deposited from a second film-forming composition comprising:

• (a) an ungelled organic polysiloxane having reactive functional groups, said polysiloxane comprising at least one unit of the following structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X is an organic polyvalent linking group which optionally contains one or more reactive functional groups, wherein the polyvalent linking group is selected from the group consisting of alkylene, oxyalkylene, and alkylene aryl, and X is derived from a material having two or more unsaturated bonds capable of undergoing hydrosilylation reaction;
• and n has a value ranging from 2 to 4 such that n is equal to the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• and
• (b) a curing agent having functional groups reactive with the functional groups of (a).

A process for applying a multi-component composite coating to a substrate comprising the following steps:

• (a) applying to a substrate a pigmented film-forming composition from which a base coat is deposited onto the substrate;
• (b) applying onto the base coat a first top coat film-forming composition from which a transparent top coat is deposited over the base coat;
• (c) applying onto the first top coat a second film-forming composition from which a second top coat is deposited, said second film-forming composition comprising:
• (i) an ungelled organic polysiloxane having reactive functional groups, said polysiloxane comprising at least one unit of the following structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X is an organic polyvalent linking group which optionally contains one or more reactive functional groups, wherein the polyvalent linking group is selected from the group consisting of alkylene, oxyalkylene, and alkylene aryl, and X is derived from a material having two or more unsaturated bonds capable of undergoing hydrosilylation reaction;
• and n has a value ranging from 2 to 4 such that n is equal to the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• and
• (ii) a curing agent having functional groups reactive with the functional groups of (i).

A curable composition comprising the following components:

• (a) at least one ungelled organic polysiloxane having reactive functional groups, said polysiloxane comprising at least one unit of the structure (I):
• wherein R1 and R2 are independently selected from the group consisting of OH and monovalent hydrocarbon groups;
• X is an organic polyvalent linking group which optionally contains one or more reactive functional groups, wherein the polyvalent linking group is selected from the group consisting of alkylene, oxyalkylene and alkylene aryl which X is derived from an organic material having two or more unsaturated bonds capable of undergoing hydrosilylation reaction;
• and n has a value ranging from 2 to 4 such that n is equal to the number of unsaturated bonds capable of undergoing hydrosilylation reaction;
• and
• (b) at least one curing agent having functional groups reactive with the functional groups of (a).