Phosphoric acid polyester and its preparation

PURPOSE: To efficiently obtain the titled polymer useful as a flame retardant agent, etc., which has a high heat resistance, by allowing a specific cyclic phosphoric acid ester to react with a tris-hydroxyalkyl cyanurate under specific conditions. CONSTITUTION: This polymer of formula I or II (wherein R is CH 2 , C 2 H 4 or C 3 H 6 ; m is 1-10; and n is 1-6) is prepared by reacting a cyclic phosphoric acid ester 2,4,8,10-tetraoxa-3,9-dioxo-3,9-dihydroxy-phophaspiro[5.5]-undecane with a tris-hydroxyalkyl cyanurate or tris-hydroxyalkyl isocyanurate at from 120 to 250°C in the presence of a catalyst such as tetra-n-butyl titanate, etc., for 2 to 12 hours while mixing intensively. COPYRIGHT: (C)1994,JPO