A Phosphorous-based Polyol for Flame Retarded Rigid Polyurethane Foam

A phosphorus-containing polyol (P-polyol) was synthesized with diethyl ethylphosphate (DEEP) and trihydroxymethyl phosphane oxide (THPO) via transesterification reaction, which was introduced into rigid polyurethane foam (RPUF) by in-situ chemical reaction. The optimum synthesis conditions of P-polyol were investigated as follows: butyldihydroxychlorostannane as catalytic agent, the molar ratio of DEEP to THPO was 1:1 at 120-170℃, the yield was over 85%, the apparent viscosity of P-polyol was 1400 MPa.S with the hydroxyl value about 480 mg KOH/g  and the acid value about 100 mg KOH/g. With the increase of adding P-polyol, the flame retardant properties of the RPUF increased continuously. When the P-polyol amount in white material was 40%, the LOI reached24.7% and vertical combustion test rated UL 94 V-0. TGA results show that the P-polyol promotes the degradation and the formation of char residue of RPUF significantly. The polyurethane foam had the characteristics of condensation phase. Simultaneously, the compressive strength of RPUF was increased by 50 % and 21% in horizontal and vertical direction, respectively, compared with neat RPUF.