Study On The Synthesis Process Of Low Water-soluble ?-type Ammonium Polyphosphate

Ammonium polyphosphate?APP?has been widely applied in polymers as flame-retardancy,since it has many excellent properties,such as high efficiency of flame retardant,good thermal stability,environmental friendly and so on.However,when APP blends with polymers,there are still several shortages that would be greatly influenced on their performances including poor compatibility,high water solubility and hygroscopicity.Recently,researchers focus on the modifications of APP to to improve the flame retardance,but ignore its own performance.In order to reduce the water solubility and increase the polymerization degree of APP,the preparation process of APP?has been deeply investigated in this paper,and the mainly contents and results has been are listed as follows.?1?The synthetic procedure of ammonium metaphosphate?AM?with high-purity has been optimized on the basis of reaction between diammonium phosphate?DAP?and phosphorus pentoxide?P₂O₅?,including temperature and time of reaction,flux of ammonia,and it is found that the optimum process conditions are as follows:DAP and P₂O₅ with the molar ratio of 2/1 are mixed in the kneader under180?for an hour.After melting completely,ammonia is impregnated into kneader with the flux of 180L/h for 5h,finally,the temperature is cooled down to the room temperature.According to the analyses of crystalline and thermal stability,the XRD spectra of AM obtained by the above process fit to the standard spectra and the AM has good thermal stability.?2?A new polymerization route of APP-II with low solubility in water has been developed,using the above AM,ammonia,P₂O₅ and polyphosphoric acid?PPA?as raw materials.The various factors affecting the water solubility have been studied,and the promising polymerization technic of APP II with low solubility is obtained.After AM,P₂O₅ and PPA being mixed together with the mole ratio of 2:1:0.8 from120?to 280?for 1h under an ammonia flux of 120L/h,the mixture is reacted for8h under an ammonia flux of 60L/h,finally,the temperature is cooled down to the room temperature.The product has stable crystalline and high purity,whose water solubility is 0.15g/100mL,polymerization degree is 823.6 and initial decomposition temperature is 311?.?3?A novel polymerization route of APP-II with low solubility in water has been developed using AM,ammonia,DAP and P₂O₅ as raw materials.Synthesis condition has been optimized through single factor and orthogonal experiment.And it is found that when the mole ratio of AM,DAP and P₂O₅ is 1:1:1,the time and the temperature of pre-polymerization is 4h and 280?,and the time,the temperature and flux of ammnium reaction is 4h,280?and 60L/h,respectively,the product has the lowest water solubility?0.13g/100mL?,the highest polymerization degree?2126?,and high initial decomposition temperature?314??.