Preparation And Application Of Microencapsulated Flame Retardant Containing Silicon And Phosphorus

The microencapsulated flame retardant containing silicon-phosphorus which was covered with SiO2 formed by the hydrolysis and polymerization of tetraethyl silicate (TEOS) based on sol-gel technique had been prepared. The silica dioxide gel was the shell of microcapsules and dimethyl methyl phosphate (DMMP) was chosen as the core materials.The work mainly consisted of four parts:(1) The factors affecting the stability of O/W emulsion were discussed and the technological parameters of preparing stable O/W emulsion were optimized. (2) The effects of the technological parameters on the preparation of microencapsulated flame retardant were studied and optimized by the average particle size and distribution of microcapsules. (3) The microencapsulated flame retardant was characterized by FT-IR spectrum, TG, SEM and qualitative test of phosphorus. (4) The cotton fabric was finished by the microencapsulated flame retardant and the flame retarding effectiveness was tested.Based on the stability tests of O/W emulsion, the optimal technological parameters for preparation of O/W emulsion were confirmed as follows, water content:40%vol; the value of HLB for built emulsifiers of Span80 and Tween20:16; the amount of emulsifier:4%wt; time of emulsification:15min; emulsification intensity:1200rpm. In addition, it was also showed by the experiment that there was a great influence on the emulsifying effect, if a certain amount of sodium chloride solution was added to the emulsion.Through the measurement of the average particle size and distribution of microcapsules, the optimal technological parameters for preparing microcapsules were confirmed as follows, amount of emulsifier:4%wt; time of emulsification:15min; emulsification intensity:1200rpm; time of polymerization:60min; polymerization intensity:700 rpm. In addition,25mL 7mol/L ammonia was added to control the rate of hydrolysis and polymerization of TEOS.The FT-IR spectrum of the microencapsulated flame retardant indicated that there were Si-O-Si groups in the structure of the surface of the microencapsulated flame retardant. Qualitative test of phosphorus element showed that DMMP was encapsulated in the flame retardant microcapsules. TG test approved that the microencapsulated flame retardant was released and acted as the flame retardant in primary stage of main pyrolysis of cotton fabric. The SEM showed that the microencapsulated flame retardant had the appearance of very regular sphere.Certain flame retarding efficiency had been verified after the microencapsulated flame retardant was used for cotton fabric.