Polyester resin for powder coating

A carboxyl group-containing polyester resin for use in a powder coating and comprising

• (a) from about 45 to 55 mole percent of an aromatic diacid component of which at least 90 mole percent is isophthalic acid,
• (b) from about 40 to about 50 mole percent of a diol component,
• (c) from about 0 to about 7 mole percent of an aliphatic diacid containing from 4 to 13 carbon atoms, and
• (d) from about 0 to about 3 mole percent of a branching agent having at least 3 alcohol or acid groups or both,
• such that the polyester resin has a glass transition temperature of 44° to 55° C., an adid number of 35-55 milligrams of potassium hydroxide per gram of resin, a hydroxyl number less than 10 milligrams of potassium per gram of resin, and a viscosity of less than 1500 centipoise as measured at 220° C. by an ICI cone and plate viscometer.