TW344756B - Low gloss powder coating composition and method for coating therewith - Google Patents

Abstract

A low gloss powder coating composition which is a thermosetting polyester resin powder coating composition comprising three thermosetting polyester resins (A), (B) and (C) and a hardener (D), characterized in that the polyester (A) has 20-38 mg KOH/g of hydroxyl value or 20-45 mg KOH/g acid value, the polyester (B) has more than 100 mg KOH/g of hydroxyl value or more than 100 mg KOH/g acid value, the polyester (C) has 40-80 mg KOH/g of hydroxyl value or 53-90 mg KOH/g acid value, the three polyester resin (A), (B), (C) have a difference in the reaction rate of polyester resin (A) and (B) based on a hardener (D) is large, and a difference in the reaction rate of polyester (A) and (C) based on a hardener (D) is small; when the modulus of elasticity for the reaction system a, b, c (in which those resins and the hardener (D) being mixed each in an equivalent ratio 0.8 to 1.25) after 3 minutes at 200℃, are Ea, Eb, Ec, the differences between the modulus of elasticity Eb-a=Eb-Ea and Ec-a=Ec-Ea are maintained in the following ranges, respectively: 20 dyn/cm2<Eb-a< 103 dyn/cm2 and 1 dyn/cm2 < Ec-a < 10 dyn/cm2 and the weight ratio of the polyester resin (A) to the polyester resin (B) is in the range of 90/10-70/30 and that of the polyester resin (A) to the polyester resin (C) is in the range of 85/15 - 60/40.