Abstract: A novel phosphorouse-nitrogen structure containing intumescent flame retardant poly(3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5.5] undecane-3,9-dioxide) hexamethylene diamine (SPHD) was prepared by 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5.5] undecane-3,9-dioxide ( SPDPC ) and hexamethylene diamine (HD) through melting ploymerization in N2. The effects of ratio of material and reaction temperature on relative molecular weight were studied by intrinsic viscosity test. The results showed that the highest yield was 84 %, and the optimal reaction conditions were as follows: polymerization time, the molar ratio of SPDPC to hexamethylene diamine, reaction temperature were about 4 hours, 1/1.1, 165 ℃, respectively. The molecular structure and thermal stability of SPHD were characterized by FT-IR，1H-NMR and TG, separately. Results showed that the products could be obtained successfully by melt polymerization, which had good thermal stability. The flame retardancy of SPHD was studied when used in PE-LD with addition of ammonium polyphosphate (APP), when the content of SPHD was 15 %, the limiting oxygen index(LOI) value was 27.2 %and V-0 rating of UL94 could be achieved.

Key words: 3, 9-dichloro-2, 4, 8, 10-tetraoxa-3, 9-diphosphaspiro-[5.5] undecane-3, 9-dioxide, hexamethylene diamine, preparation, melt polymerization, intumescent flame retardant