Synthesis And Flame Retardant Properties Of Multielement Spiro Phosphorus Flame Retardants

With the rapid development of the flame retardant industry, multielement coordination compounds of phosphorus flame retardant has attracted widespread attention because of its high efficiency. Compared to multicomponent synergistic flame retardant, multielement coordination compounds in a single molecular is more advantageous to play a synergistic effect and avoid the space interaction of molecules. Halogen-free multielement coordination spiro phosphate ester flame retardant has high thermal stability, low toxicity, small mobility and good durability. These kinds of flame retardants meet the demands of the development of flame retardant industry, has an expansive development prospect.In this paper, the synthetic process of spirocyclic pentaerythritol bisphosphorate disphosphorylchloride(SPDPC) was improved and characterized by FTIR, NMR and TG. SPDPC was used as intermediate to react with the nitrogen compounds containing hydroxyl, amino and inorganic metal salt, and finally achieved three novel multielement coordination flame retardant in a single molecular. Feasibility research was explored to study whether these novel flame retardants had efficiency on resins. Flame retardant mechanism was also studied by a variety of testing methods. Finally these novel flame retardants was verified to be high efficient, environmental friendly and suitable for large-scale industrialization.(1)The synthesis process of SPDPC was improved with phosphorus oxychloride, pentaerythritol as raw materials, toluene as solvent. The consumption of phosphorus oxychloride was greatly reduced by 45% and the reaction time was dramatically shortened to 14 h. Its chemical structure was confirmed by FTIR, NMR, TG and melting point test. The target product remained high purity and yield.(2)A novel self-intumescent flame retardant, tris(2-hydrooxyethyl) isocyanurate spirocyclic pentaerythritol bisphosphonate ester(THECP), was synthesized through solution polycondensation by tris(2-hydroxyethyl) isocyanurate and SPDPC. The product was characterized by FTIR, NMR and TG. When 30% THECP was added, LOI increased to 32.9, UL-94 test reached V-0 level. Their combustion performance and thermal properties were evaluated by CONE, TG and TG-FTIR. The morphology and chemical structure of residual chars were observed by SEM and FTIR. The results illustrated that THECP can greatly increase residual chars and delay the decomposition rate of matrix. THECP and ammonium polyphosphate contributed to fully exerting in condensed phase effects.(3)A novel self-intumescent flame retardant, imidazole spirocyclic phosphoramidate(ISCP), was synthesized by SPDPC and imidazole. The product was characterized by FTIR, NMR and TG. When 20% ISCP was added, LOI increased to 36.8, UL-94 test reached V-0 level. Their combustion performance and thermal properties were evaluated by CONE, TG and TG-FTIR. The morphology and chemical structure of residual chars were observed by SEM and FTIR. The results illustrated that ISCP can greatly increase residual chars and delay the decomposition rate of matrix. ISCP contributed to fully exerting in condensed phase.(4)A novel flame retardant, spirocyclic phosphoramidate aluminum(ALCP), was synthesized by SPDPC and inorganic aluminum salts. The product was characterized by FTIR, NMR, TG, Zetasizer, XRD, XPS and XRF. When 20% ALCP was added, LOI increased to 30.2, UL-94 test reached V-1 level. Their combustion performance and thermal properties were evaluated by CONE, TG and TG-FTIR. The morphology and chemical structure of residual chars were observed by SEM and FTIR. The results illustrated that ALCP can greatly increase residual chars and delay the decomposition rate of matrix. ISCP contributed to fully exerting in condensed phase.