Preparation Of New Nitrogen-containing Flame Retardants And Applied Research

Intumescent halogen-free flame retardant technology has become the one of the most active areas.Melamine phosphate salt is the type of intumescent flame retardant for a faster development.This paper researched the preparation of halogen-free,nitrogen-containing intumescent flame retardants(IFR) and their application in fireproof coating.(1) Melamine phosphates (MP),melamine pyrophosphate(MPY) and melamine polyphosphate(MPOP) were prepared successfully in solvent.And in order to reduce the emission of pollutant,the intumescent flame retardant named melamine salt of pentaerythritol phosphate(MPP) was synthesized from phosphoric acid instead of phosphorus oxychloride(POCl₃) in the conventional technology.The intermediate- pentaerythritol phosphate was prepared and characterized to speculate the molecular structure and the reaction mechanism of melamine salt of pentaerythritol phosphate(MPP).(2) The melamine polyphosphate(MPOP) and melamine salt of pentaerythritol phosphate(MPP) were further prepared in solid-phase.The preparation process was no pollution.(3) The effects of reaction temperature,time and molar ratio on each reaction were discussed in this paper.The optimum synthetic conditions in solvent and in solid were obtained from single factor experiments and orthogonal experiments.The structure and thermal behaviors were characterized and studied by FT-IR,MS,NMR,TG-DTA and DSC respectively,the IR spectrum of the products showed that they were basically consistent with the literature,and the reaction mechanism and the flame-retardant mechanism were discussed.The result showed that the optimum molar ratio of phosphoric acid,pentaerythritol and melamine in the preparation of melamine salt of pentaerythritol phosphate(MPP) in solvent was 2.5:1.0:2.0,and its reaction temperature and time in the first step were 120℃and 4 h respectively.And the reaction temperature and time in the second step were 70℃and 4 h respectively.It started melting and degrading at about 240℃, and the char yield could reach 36%at 800℃.The optimum molar ratio of P₂O₅,H₃PO₄, melamine and pentaerythritol in the preparation of melamine salt of pentaerythritol phosphate (MPP) in soild was 2.0:1.0:2.1:1.0,and the reaction temperature and time were 200℃and 4 h respectively.(4)Then the products were applicated in fireproof coating,the molar ratio and preparation process were designed,and a variety of performance of the coating was also studied.The result showed that the limited time of fire-endurance of fireproof coating containing melamine salt of pentaerythritol phosphate(MPP) was 39.5min,and its performance also better than the national standards,which showed that such a coating was an excellent fireproof coating.