Preparation and characterization of polyurethane flame-retardant coatings using pyrophosphoric lactone-modified polyesters/isophorone diisocyanate-isocyanurate

Pyrophosphoric lactone-modified polyester containing two phosphorous functi onal groups in one structural unit of base resin was synthesized to prepare a nontoxic, reactive flame-retardant coatings. Then, the pyrophosphoric la ctone-modified polyester was cured at room temperature with isocyanate and isophorone diisocyanate (IPDI)-isocyanurate to get a two-component polyuret hane flame-retardant coatings (TAPPU). Comparing the physical properties of the films of TAPPU with the film of nonflame-retardant coatings, no deteri oration of physical properties was observed with the incorporation of a fla me-retarding component into the resin. Three kinds of flame retarding tests were conducted, including the 45 degrees Meckel burner method, limiting ox ygen index method (LOI method), and oxygen combustion method with Cone calo rimeter. It was observed that the char lengths were 3.1 similar to4.5 cm an d LOI values were 27 similar to 30%. These results indicate that the prepar ed coatings are good flame-retardant ones. It was also found that the flame retardancy of those coatings was increased with the contents of phosphorou s. (C) 2001 John Wiley & Sons, Inc.