Low-cure powder coatings and methods for using the same

Abstract

Low-cure powder coating compositions are disclosed. The compositions comprise a polyepoxide and a material having the structure wherein R 1 is an organic radical having 6 to 25 carbon atoms; R 2 is an organic radical having 1 to 20 carbon atoms; R 3 and R 4 are independently alkyl or phenyl groups having 1 to 8 carbon atoms; Z is oxygen or nitrogen, and when Z is oxygen R 5 is absent and when Z is nitrogen R 5 is hydrogen or is and n is 1 to 4. The material can optionally be reacted with an acidic hydrogen-containing compound. The compositions are curable without the use of crosslinking agents or accelerators. Methods for coating a substrate using these compositions, and substrates coated thereby, are also disclosed, as are additional catalysts useful for the same purpose.

1 . A curable powder composition comprising: 
 (a) a polyepoxide; and    (b) the reaction product of a polyisocyanate and either an amine comprising a primary or secondary amine group and a tertiary amine or an alcohol or polyol containing a tertiary amine.    
     
     
         2 . The composition of  claim 1 , wherein the reaction product is formed from a polyisocyanate and an amine comprising a primary or secondary amine group and a tertiary amine.  
     
     
         3 . The composition of  claim 2 , wherein the polyisocyanate is a diisocyanate.  
     
     
         4 . The composition of  claim 3 , wherein (b) is mixed with an acidic hydrogen-containing compound.