| Halogen-free flame-retardant finishing of textiles is of great significance.Natural clay is cheap,green,non-toxic and easy to obtain,having been used more and more as flame retardant substance in the flame retardant research of fabrics.Sepiolite（Sep）is a kind of silicate clay,which is composed of silico-oxygen tetrahedron and magnesic-oxygen octahedron.Sep has a special fibrous morphology and good flame retardancy.Silica sol film obtained by Sep was brittle.In order to make Sep evenly attached to the fabric,a new type of phosphorus-rich organic-inorganic hybrid flame retardant silica sol was prepared by ion replacement reaction of sepiolite（Sep）with phosphorus-containing biomass phytic acid（PA）.The structure and morphology of sepiolite-based silica sol were studied by transmission electron microscope,field emission scanning electron microscope,inductively coupled plasma analysis,X-ray diffraction spectroscopy,29Si solid NMR and X-ray photoelectron spectroscopy.The results show that magnesium ions in the Sep are successfully replaced by hydrogen ions of PA,forming a unique beaded structure on the sepiolite fiber.The hybrid silica sol has good film forming performance,and the solidified film has good flexibility and stretchability.In addition,the prepared sepiolite/phytic acid（Sep/PA）silica sols were used as flame retardant to finish the T/C fabric.The flame retardant and mechanical properties of T/C fabric were improved by Sep/PA silica sol coating,and the coated T/C fabric had a certain fastness to washing.When the baking temperature was 180℃and the baking time was 5min,the elongation of the coated T/C fabric reached 23.0%,which was 78.3%higher than that of raw T/C fabric.In order to further improve the flame retardant and mechanical properties of Sep/PA silica sol coating,nitrogenous polyaspartic acid（PASP）was added into Sep/PA silica sol system and the sepiolite/phytic acid/polyaspartic acid（Sep/PA/PASP）silica sol was applied to T/C fabric.The mechanical tensile test results show that the addition of polyaspartic acid could improve the flexibility of the membrane materials.Scanning electron microscopy and infrared spectroscopy test results show that the Sep/PA/PASP silca sol coating was successfully coated on the T/C fabric.The results of Thermogravimetric analysis,vertical combustion test,ultimate oxygen index test and mechanical tensile test show that the Sep/PA/PASP silica sol coating can improve the thermal stability and flame retardant properties of T/C fabric,and also improve the mechanical properties.The limit oxygen index of coated T/C fabric was 36.1%.The hybrid sepiolite-based silica sol has broad application prospect. |
