Surface Modification Of Microencapsulated Flame Retardant And Its Application On Cotton Fabric

In this paper, silica sol containing reactive group was prepared with tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors and was used to modify the surface of microencapsulate in which the core material was organo-phosphorus flame retardant. The modified microencapsulated flame retardant could show better flame retarding efficiency and wash fastness.The work mainly consisted of four parts:(1) The optimal technical parameters for the modified silica sol (such as the amount of water, catalyst, solvent, the ratio of TEOS and GPTMS, the temperature) were identified and the reasons for sol stability and gel flexibility were discussed. The particle size measurement and the analysis of FT-IR spectrum were used to characterize the sol structure. (2) The microencapsulated flame retardant was modified with the silica sol and FT-IR spectrum, energy spectrometer and SEM were used to characterize the modified microencapsulated flame retardant. (3) DSC was used to identified the thermal property of the modified microencapsulated flame retardant. (4) The cotton fabric was finished by the modified microencapsulated flame retardant and the effectiveness and durability of the flame retardant were tested.The results of first part of experiment indicated that the best synthesis conditions of silica sol were:n(H2O):n(Si-OR)=2, n(HC1):n(Si)=0.014, n(C2H5OH):n(Si)=4, n(GPTMS):n(TEOS) =1, reaction temperature was 50℃, drying temperature was 60℃. The results of particle size measurement and FT-IR spectrum indicated that particles in the sol were mainly distributed between 160nm to 260nm and there were many epoxy groups in modified silica sol. The test results of energy spectrometer proved that there was Si element on the surface of modified microencapsulated flame retardant. The FT-IR spectrum of modified microencapsulated flame retardant indicated that there were Si-O-Si groups in the structure of modified microencapsulated flame retardant. In the SEM imagines it was very clear that the silica gel had been deposited on the surface of the microencapsulated flame retardant.It was found in the thermal analysis that the surface modification of microencapsulated flame retardant made the maximum heat absorption peak transfer from 353.31℃to 319.87℃, which means there will be more flame retardant released from the microcapsules before the temperature of cotton fabric reaches to 350℃which is the burning point of the cotton fabric.Better flame retarding efficiency has been obtained after the modified microencapsulated flame retardant was used for cotton fabric. Compared with unmodified one, the durability of flame retardant was greatly improved.