Study On The Preparation Of High Efficient Inorganic Retardant--APP

Ammonium polyphosphate (APP) had been gotten wide attention in regard to its excellent characterization on flame retardant. The key to further extend the application of APP is a method with high degree of polymerization, high purity and high yield.â…¡-APP has long been industrialized abroad, and in contrast the quality of domestic products are not ideal. For the reasons of laggard synthesis technology and lacking of basic research, the application and development of ammonium polyphosphate flame retardants were seriously affected and its social &economic benefits were reduced. Deep investigation onâ…¡-APP synthetic technology, effect of reaction conditions on it, and further improving its average degree has been studied in this paper. So it has an important value both in economic and scientific research field.The study of reaction system was constructed, compared two methods: the polymerization of (NH₄)₂HPO₄ and P₂O₅, the polymerization of CO(NH₂)₂ and H₃PO₄, the synthetic technology was deeply investigated that (NH₄)₂HPO₄ and P₂O₅ were used as raw materials. The rote of experiments was as follow: simulating ambience, discussing the other factors and seeking optimum technology. Some factors on degrees polymerization of APP such as varieties of (NH₄)₃PO₄, reaction atmosphere, components proportion, reaction temperature, reaction time, reaction pressure, post-processing temperature and time were investigated.The results could be showed as follow: when (NH₄)₂HPO₄, P₂O₅ and urea (molar ratio for 1∶1∶0.3 ) were uniformly mixed, then polymerization was aroused for more than 50 min under 285℃, at the atmosphere of NH3, after it was finished, it was heated for about 120 min under 250℃. In the end, high degree polymerization of APP was prepared, the average polymerization degree of the prepared APP was more than 390 analyzed by end-group titrimetric analysis-differential spectrosmetry. It has good quality, broke through the limitation that the average polymerization degree of APP was smaller than 100 reported domestic. This method was simple, convenient and feasible, with a lower capital cost and operation cost, and less dangerous. Ammonium phosphate was synthesized with lower decomposition temperature and solubility, and its quality was up to national standards.