Powder coating composition of semi-crystalline polyester and curing agent

A process of preparing a thermosetting powder coating composition comprising the steps of:

• (1) blending or mixing a co-reactable particulate mixture of a carboxylic acid-functional polyester component and a curing agent having groups reactive with carboxylic acid groups, said mixture optionally also including one or more pigments or additives;
• and (2) comminuting said blend or mixture, wherein the carboxylic acid-functional component comprises:
• (A) at least one semi-crystalline polyester having one or more Tg values no more than 55° C., a sharp melting point of from 50° C. to 200° C., an acid value of from 10 to 70 mg KOH per gram and a number average molecular weight of at least 1600 in an amount of from about 5% to about 90% by weight, and
• (B) at least one amorphous polyester containing from 65 to 100% by weight of isophthalic acid, calculated on all of the acid constituents, having a Tg of at least 30° C. and an acid number of from 15 to 90 mg KOH per gram in an amount of from about 10% to about 95% by weight, the weight of the amorphous polyester being calculated on the combined weight of the total polyesters (A) and (B).