Novel Phosphorus-based Flame Retardant Rigid Polyurethane Foam

Rigid polyurethane foams?RPUF? is widely used in construction and pipelines due to its excellent heat insulation and heat preservation performance. However RPUF is the extremely flammable and a large number of toxic and harmful gases are released during its combustion process. So it is necessary to further improve the potential flame retardant properties of RPUF. In this paper, a new phosphorus containing flame retardant polyether polyol?THPPG?, hex?p-hydroxymethyphenoxy?cyclotriphosphazene and dimethyl methyl phosphate?DMMP? as flame retardant were used in RPUF.Firstly, HHPCP and DMMP were used in RPUF and the flame retardant and mechanical property were investigated. When mass ratio of HHPCP and DMMP was 20:20, the total heat release of RPUF decreased from 21.6 kJ·g^-1 to 16.9 kJ·g^-1, the compression strength was up to 72 k Pa. The char residue of flame retardant RPUF increased to 22.5 % from 7.2 %. Although the LOI of flame retardant RPUF increased to 24.5 %, but it didn't reach the B2 level?LOI ? 26 %?.Secondly, the phosphorus-containing polyether polyol?THPPG? was prepared from trimethylol oxychloride and propylene oxide and the structure of the product was characterized by FTIR. The optimal synthesis conditions of THPPG were discussed. Hydroxyl value of THPPG was about 544-746 mg KOH kJ·g^-1 and phosphorus content was about 8.5^-12.3%. When the adding amount of THPPG was 50 phr in RPUF, the compressive strength of RPUF was up to145 k Pa, the LOI of flame retardant RPUF increased to 24.0 %, and the char residue of flame retardant RPUF increased to 24.1 % from 19.5 %, the total heat release of RPUF decreased to 12.9 kJ·g^-1 from 20.3 kJ·g^-1.Moreover RPUF bubble collapse temperature?T50%? increased to 387 from 350 ? ?.Thirdly, THPPG/HHPCP and THPPG/DMMP were used to prepare the flame RPUF respectively. When mass ratio of THPPG and HHPCP was 100:25, the LOI of flame retardant RPUF was up to 26.1%, reach the B2 level?LOI ? 26 %?. And more the char residue of flame retardant RPUF increased to 27.9 %, the total heat release of RPUF decreased to 11.3 kJ·g^-1 from the 20.3 kJ·g^-1. When mass ratio of THPPG and DMMP was 100:25, the LOI of flame retardant RPUF was up to 30.2 %, reach the B1 level?LOI ? 30 %?, the char residue of flame retardant RPUF 25.1 %, Moreover the total heat release of RPUF decreased to 10.3 kJ·g^-1.