Powder coating composition of epoxy resin mixture and carboxyl-containing polyester

摘要

A powder coating composition comprising (A) a solid epoxy resin mixture that comprises at least one epoxy resin component (A1) and one epoxy resin component (A2) and (B) a free-carboxyl-group-containing polyester in an amount sufficient for the full cure of the composition, in which the epoxy resin component (A1) consists of one or more epoxy resins and has overall a mean epoxy functionality that is greater than 2, wherein the epoxy resin component (A2) consists of one or more advanced epoxy resins each of which has a mean epoxy functionality of at least 1.2 but less than 1.95 and is the product of a reaction in which (i) at least one diglycidyl compound is simultaneously reacted with (ii) at least one bisphenol compound and (iii) at least one monophenol as starting materials, and the difference between the mean epoxy functionality of the epoxy resin mixture (A) and the mean epoxy functionality of component (A2) of the mixture is at least 0.05 but less than 0.8.