Flame Retardant Finish Of Silk Fabrics By Modified Silica Sol

Sol-gel technique is widely used because of its simple operation,low reaction temperature and easy control,which meets the demands of the development of energy conservation and emission reduction in today’s world.In this paper,the amino-containing silica sol with certain flame retardancy was prepared by sol-gel technique,and the flame retardants with different flame retardant elements and the silica sol were applied in silk fabrics to endow the silk fabric with good flame retardancy.Based on a variety of combustion tests,the synergistic flame retardant effect between phosphorus and nitrogen,boron and nitrogen and phosphorus and boron were studied.The amino-containing silica sol was prepared with sol-gel technology using(3-(Trimethoxysilyl)propyl)ethane-1,2-diamine(AEPTES)as precursor.The influences of precursors,ethanol and water amounts,and the solution p H value on the limited oxygen index(LOI)of finished silk were discussed.Thus the optimum preparation process conditions of silica sol containing amino.The limited oxygen index of the fabrics that treated by silica sol and benzyl phosphonic acid reached 29.7%.The different combustion tests show that the residual carbon amount of treated fabrics increased,the maximum heat release rate,total heat release quantity and smoke density significantly reduced,and the vertical combustion result met the standard B1 level of flame retardant fabrics(decorative fabric).The treated fabrics had the best flame retardant performance in the presence of both nitrogen and phosphorus elements,the reflecting the synergistic flame retardant effect between phosphorus and nitrogen.The prepared amino-containing silica sol was modified using boric acid as flame retardant additives.The influences of the dosage of various chemical reagent and the solution p H on the LOI of treated fabric were investigated.The results indicate that the boric acid flame retardant can significantly promote the LOI of the treated fabrics and the LOI increased by 10%.With the increase of the solution p H,the LOI of the treated fabrics can be improved,and the influences of precursor,3-Glycidyloxypropyltrimethoxysilane and ethanol on the treated fabrics were not particularly significant.Scanning electron microscopy(SEM)results indicate that the surface of fabric was coated by a layer of complete film.The micro combustion,thermogravimetric analysis,smoke density and vertical burning test results show that the maximum heat release rate of the treated fabrics and smoke density significantly reduced,weight retention rate increased by about 15%,and the damaged length reduced from 30 cm to 12.51 cm.To sum up,the boron element had a good smoke suppression property,and it could increase the flame retardant effect combined with nitrogen,showing synergistic flame retardant effect of boron and nitrogen.Boron phosphate(BPO4)was doped in industrial silica sol.Taking the LOI value of treated silk fabrics as measurement index,the best finishing process was obtained as follows: the mass concentration of BPO4 30 g/L,silica sol 30 m L,the curing temperature 130 ℃,the curing time 3 min..On the basis of best doping amount of BPO4,citric acid,tartaric acid and sodium phosphite(SHP)were added to the doped silicon sol.By testing the LOI of washed silk fabric finished by different formulation,the optimum doping amount of each chemical reagent was achieved.The results show that the treated fabrics had durable flame retardancy,and the LOI value of the fabrics was still 26.2% after 30 times washing.The infrared spectroscopy and scanning electron microscopy tests indicate that the boron phosphate was embedded in film of Si O2,and was combined with surface groups of the fabric.The combustion tests results show that the boron phosphate can effectively reduce the total heat release,smoke release quantity and the damaged length of the fabric,realizing the synergistic flame retardant effect of boron and phosphorus.