Ppg Industries Ohio, Inc.

Jackie L Smith

Anthony Michael Chasser

Ronald R Ambrose

Shengkui Hu

John R Schneider

Modified aminoplast crosslinkers and powder coating compositions containing such crosslinkers

Provided is a crosslinking agent which is the ungelled reaction product of a polyester polyol and an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The polyester polyol is the reaction product of a cycloaliphatic polyol and a cyclic polycarboxylic acid or anhydride. The crosslinking agent is essentially free of hydroxyl functionality and has a glass transition temperature of at least 10&deg; C. Further provided is a powder coating composition including a solid particulate film-forming mixture of a polymer containing reactive functional groups and having a T of at least 30&deg; C., and the crosslinking agent. Additionally provided is a multi-layer composite coating composition having a basecoat layer deposited from a basecoat film-forming composition and a topcoat over the basecoat deposited from the previously described powder coating composition. Coated substrates are also provided.

Aminoplast-based crosslinkers and powder coating compositions containing such crosslinkers

A crosslinking agent which is an ungelled reaction product of (a) at least one aminoplast resin, (b) at least one polyfunctional polymer having functional groups reactive with aminoplast resin (a) and having a glass transition temperature of at least 15&deg; C.; and (c) at least one compound different from (b) having active hydrogen groups reactive with aminoplast resin (a) is provided. Also provided is a method for preparing the crosslinking agent. Further provided is a powder coating composition which includes the crosslinking agent. Additionally provided is a multi-layer composite coating composition having a base coat layer and a top coat over the base coat deposited from the previously described powder coating composition. Coated substrates are also provided.

The present invention provides a crosslinking agent which may have reactive benzoxazine groups prepared from (a) at least one aromatic compound, (b) at least one aminotriazine compound, and (c) at least one other compound having active hydrogen groups reactive with aminoplast compound (b). The crosslinking agent is essentially free of hydroxyl functionality and has a glass transition temperature of at least 25&deg; C. The present invention is further directed to a method for preparing the above-described crosslinking agent, and a curable powder coating composition comprising a mixture of (A) a polymer having functional groups reactive with aminotriazine and/or benzoxazine groups having a glass transition temperature of at least 30&deg; C.; and (B) the above crosslinking agent. Multilayer composite coating compositions are also provided including a basecoat deposited from a film-forming composition and a topcoat over the basecoat, deposited from the curable powder coating composition described above. Coated substrates are also provided.

The present invention provides a crosslinking agent having reactive benzoxazine groups which is the ungelled reaction product of (a) at least one mono-hydroxy aromatic compound and (b) at least one aminotriazine compound having one or less non-alkylated NH group present in a molar ratio of reactant (a) to reactant (b) ranging from 1.0 to 3.0: 1.0, provided that where reactant (a) is a single ring monohydroxy aromatic compound, the molar ratio of reactant (a) to reactant (b) ranges from 1.0 to 1.8:1.0 and from 2.2 to 3.0:1.0. The crosslinking agent is essentially free of hydroxyl functionality and has a glass transition temperature of at least 25&deg; C. The present invention is further directed to a method for preparing the above-described crosslinking agent. Also provided is a curable powder coating composition comprising a solid particulate, film-forming mixture of (A) a polymer having functional groups reactive with aminotriazine and/or benzoxazine groups, the polymer having a glass transition temperature of at least 30&deg; C.; and (B) the previously described crosslinking agent. Multilayer composite coating compositions are also provided including a base coat deposited from a film-forming composition and a topcoat over the base coat. The topcoat is deposited from the curable powder coating composition described above. The present invention further provides coated substrates.

Two types of aminotriazine-based crosslinking agents are provided. Crosslinking agent I includes the ungelled reaction product of (A) a reactive urethane group-containing reaction product and (B) an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The reactive urethane group-containing reaction product (A) is the reaction product of (1) a polyester polyol, and (2) a mono-isocyanate. The crosslinking agent I is essentially free of urethane NH functionality and has a glass transition temperature of at least 25&deg; C. Crosslinking agent II includes the ungelled reaction product of (A) a reactive urethane group-containing reaction product and (B) an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The reactive urethane group-containing reaction product (A) is the reaction product of (1) a polyisocyanate and (2) a monohydric capping agent. The crosslinking agent II is essentially free of urethane N&mdash;H functionality and has a glass transition temperature of at least 10&deg; C. Methods for preparing crosslinking agents I and II are also provided. Further provided is a curable composition of a film-forming polymer having reactive functional groups and the previously described crosslinking agent II. Also provided are powder coating compositions which each include a solid particulate mixture of a reactive group-containing polymer having a T of at least 30&deg; C. and the previously described crosslinking agents I or II. Multilayer composite coating compositions and coated substrates are also provided.

Two types of aminotriazine-based crosslinking agents are provided. Crosslinking agent I includes the ungelled reaction product of (A) a reactive urethane group-containing reaction product and (B) an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The reactive urethane group-containing reaction product (A) is the reaction product of (1) a polyester polyol, and (2) a mono-isocyanate. The crosslinking agent I is essentially free of urethane NH functionality and has a glass transition temperature of at least 25&deg; C. Crosslinking agent II includes the ungelled reaction product of (A) a reactive urethane group-containing reaction product and (B) an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The reactive urethane group-containing reaction product (A) is the reaction product of (1) a polyisocyanate and (2) a monohydric capping agent. The crosslinking agent II is essentially free of urethane N&mdash;H functionality and has a glass transition temperature of at least 10&deg; C. Methods for preparing crosslinking agents I and II are also provided. Further provided is a curable composition of a film-forming polymer having reactive functional groups and the previously described crosslinking agent II. Also provided are powder coating compositions which each include a solid particulate mixture of a reactive group-containing polymer having a T of at least 30&deg; C and the previously described crosslinking agents I or II. Multilayer composite coating compositions and coated substrates are also provided.

A crosslinking agent having reactive benzoxazine groups is provided. The crosslinking agent is the ungelled reaction product of a polyhydric aromatic compound and an aminotriazine compound having one or less non-alkylated NH bond per triazine ring. The crosslinking agent is essentially free of hydroxyl functionality and has a glass transition temperature of at least 10&deg; C. Additionally provided is a method for preparing the crosslinking agent. Also provided is a curable powder coating composition including a solid particulate, film-forming mixture of a polymer having functional groups reactive with benzoxazine groups and the crosslinking agent. Further provided is a multilayer composite coating composition having a base coat layer deposited from a film-forming base coating composition and a topcoat layer deposited from the curable powder coating composition. Coated substrates are also provided.

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Mars, PA, United States of America

Jackie L Smith