Powder coating composition comprising a polyester and a β-hydroxyalkylamide as crosslinker

Abstract

The invention relates to a thermosetting powder coating composition comprising a crosslinker and a polyester, wherein the polyester has functional groups which functional groups are capable of reacting with β-hydroxyalkylamide groups, wherein the polyester is prepared from at least the following monomers: neopentylglycol, a difunctional alcohol other than neopentylglycol; isophthalic acid, terephthalic acid, optionally adipic acid and a branching monomer chosen from the group of an at least trifunctional carboxylic acid, an at least trifunctional alcohol, an at least trifunctional hydroxy carboxylic acid and mixtures thereof, wherein the amount of difunctional alcohol other than neopentylglycol in the polyester ranges from 1 to 50% w/w based on the polyester, wherein the amount of isophthalic acid in the polyester ranges from 6 to 35% w/w based on the polyester, wherein the polyester has a functionality of at least 2.1, wherein the crosslinker is a compound having β-hydroxyalkylamide groups. This thermosetting powder coating composition has the ability to be cured at low temperature, while at the same time being able provide powder coatings having at least two of the following three properties: limited blooming to no blooming, an acceptable smoothness, sufficient impact resistance.