Syntheses and characterizations of two-component polyurethane flame retardant coatings using 2,4-dichloro modified polyesters

Polyurethane flame retardant coatings are composed of polyols and polyisocyanates. Flame retardant groups are usually introduced to the polyol structure. In this research intermediates were obtained by esterification of 2,4-dichlorobenzoic acid and trimethylolpropane for the purpose of introducing a flame retardant group to the polyol structure. Then chlorine-containing modified polyesters were synthesized by polycondensation of trimethylolpropane, adipic acid, 1,4-butanediol, and the intermediate. The content of 2,4-dichlorobenzoic acid in the intermediate was varied with 10, 20, and 30 wt%. Two-component polyurethane flame retardant coatings were prepared by blending the products with polyisocyanate. Various physical properties of these new flame retardant coatings were comparable to non-flame retardant coatings. They showed drying times of four to seven hours and pot life times of 14–20 hr, which could belong to the flame retardant coatings with long pot life time. The coating with 30 wt% 2,4-dichlorobenzoic acid showed a self-extinguishing property in the vertical burning test. Dept. of Chemical Engineering, Yongin 449-728, Korea. Ansan 425-110, Korea.