Preparation of Siloxane-Modified DOPO Flame Retardant Sol–Gel and Its Study on Flame Retardant PET Fabrics

In order to improve the flame retardant and anti-melt-drip performance of PET fabrics in an environmentally friendly and simple way, two transparent phosphorus-containing silicone sols (DOPO-KH560,DOPA-KH602) based on 9,10-dihydro-9,10-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and silane coupling agents (KH560/KH602) were prepared and applied to the surface of PET fabrics using roll-baking process. The results of Micro Combustion Calorimeter (MCC) tests showed that the heat release capacity (HRC) and peak heat release rate (PHRR) of the DOPO-KH560 sol–gel finished fabric were reduced by 26 and 29% respectively. And the HRC and PHRR of the DOPA-KH602 sol–gel finished fabric were reduced by 35 and 46% respectively. The SEM and EDS results showed that the two silicone gel coatings were evenly distributed on the PET fabric. Thermogravimetric tests showed that both PET fabrics with silicone gel flame retardant exhibited higher charring rates at higher temperatures. Scanning electron microscopy of the residual char showed that both silicone gel flame retardant coatings promoted the formation of a rough char layer on the PET fabric. Based on the results of thermal cracking gas chromatography, Raman and X-ray photoelectron spectroscopy of the carbon residues, the mechanism of the flame retardant PET fabrics with the two silica gel coatings was investigated. This study provides a simple method to produce flame-retardant and drip-resistant PET fabrics using environmentally friendly chemicals through an already industrialized roll-drying process.