POLYESTER RESIN AND COMPOSITION FOR FLAME-RETARDANT POWDER COATING

PURPOSE: To obtain a polyester resin capable of giving a coating film excellent in flexibility, impact resistance and flame retardancy by copolymerizing an arom. dicarboxylic acid component and an aliph. glycol component as the main components with at least a given amt. of a specific phosphorus compd. CONSTITUTION: This polyester resin is one having a hydroxyl no. of 14 to 100mg KOH/g and an intrinsic viscosity of 0.15 to 0.40, and prepd. by copolymerizing an arom. dicarboxylic acid component and an aliph. glycol component as the main components with a phosphorus compd. of formula I, II, III or IV (wherein R , R and R are each a 1-18C hydrocarbon group; R and R are each H or a 1-18C hydrocarbon group; A is a bivalent org. group; A is a trivalent org. group; R and R are each an ester-forming group; R and R , and R and R may be combined together to form a ring; and the compds. of formulae III and IV may be each in the form of an acid anhydride), the amt. of which is at least 500ppm in terms of P atom. The resin is comparatively inexpensive and is capable of giving a coating film showing excellent flexibility, impact resistance and flame retardancy.