Synthesis Of Ammonium Polyphosphate By Ammonium Dihydrogen Phosphate And Urea

Ammonium polyphosphate(APP)is one of the typical non-halogen intumescent flame retardants.Because of the characteristics such as the high efficient,the low capital cost,the excellent thermal stability,the less harmful for humans and the environmentaliy friendly advantage,it had become the hot sport in the field of the flame retardant.What's more,its prospect and development are also wide.Some external nations have realized industrialization on producing type ?-APP.Comparatively the products of domestic enterprises are not ideal on quality,which have greatly influenced APP's beneficial result on society and economy in our country.In this paper,the optimum synthesis condition of ammonium polyphosphate is explored,further improving quality of ?-APP,and modification of the product is studied,provides a basis for the production and application of APP.In the self-group reaction device,the effects of reaction time,reaction temperature and batching ratio on the properties of ammonium polyphosphate were discussed by a single variable method using ammonium phosphate-urea polymerization method and ammonium phosphate-urea-phosphorus pentoxide polymerization method to prepare ammonium polyphosphate.The phosphorus content of the product was determined by gravimetric method,the nitrogen content of the product was determined by distillation method,and the average degree of polymerization of the product was determined by XRD and terminal titration method.The data of the study had shown that,the ammonium phosphate-urea polymerization method optimal technological conditions were as follow: the ratio of raw material(ammonium phosphate: urea)was 1?1.1,the reaction time was 1.5 h,the reaction temperature was 260?,the phosphorus content could reach 73.9%,nitrogen content could reach 14.9%,the average degree of polymerization of 47.5.The ammonium phosphate-urea-phosphorus pentoxide polymerization method optimal technological conditions were as follow: the ratio of raw material(ammonium phosphate: urea: phosphorus pentoxide)was 1?0.3?1,the reaction time was 1 h,the reaction temperature was 270?,the phosphorus content could reach 72.8%,nitrogen content could reach 13.7%,the average degree of polymerization of 58.7.The two methods of preparation of the APP are much higher than that of the industrial polyphosphate.On the other hand,this paper chose Vinyltrimethoxysilane as the coupling agent to modified the product,tested the distinction between the various kinds of samples,with different reaction temperature and the mass fraction of the coupling agent,such as the degree of depression,the thermal stability,the solubility and the type of the crystal form.The study had shown that,but for the solubility,other characteristics of the modified APP all got an improvement,and the crystal form had not been changed.The conclusion was as follow: when the reaction temperature was 60?,and the mass fraction of the coupling agent was 5%,the product could got the best modification effect.