Preparation And Performance Study Of Silicon-Phosphorus Flame Retardant Anti-Droplet Recycled Polyester

Recycled polyester(RPET)is a chemical fiber raw material recycled from waste polyester products.It has a large quantity and wide range,but it is flammable and will produce a large number of melting drops when burning,which brings great harm to people’s life and property safety,and also limits the expansion of its application field.Therefore,it is of high application value to study the flame retardant and droplet resistant modification of recycled polyester.In this paper,the phosphorous flame retardant[(6-oxy-6h-dibenzo[c,e][1,2]oxy-hexacyclo-6-yl)methyl]succinic acid(DDP)was modified by esterification.Nuclear magnetic resonance hydrogen spectroscopy(1H-NMR)and Fourier infrared spectroscopy proved the successful preparation of DP-EG flame retardant.Then DP-EG flame retardant was copolymerized with regenerated dihydroxyethyl terephthalate(BHET)to produce phosphorous flame retardant regenerated copolyester PET-x P,whose weight average molecular weight was48646～69299.The results showed that the characteristic peak of hydrogen proton on methylene on DDP unit appeared on the hydrogen nuclear magnetic spectrum of phosphorous flame-resistant regenerated copolyester,and the peak area was close to the theoretical value,indicating that DP-EG copolymerized into the PET macromolecular chain successfully.With the addition of DP-EG flame retardant copolymer increasing,the residual carbon content of phosphate-based flame retardant regenerated copolyesters at 800℃also increased gradually.The residual carbon content of PET-11P reached 7.0 wt%,and the ultimate oxygen index and vertical combustion grade reached 28.1%and V-2,respectively.In order to further improve the melt drop resistance of flame retardant regenerated copolyesters,the silicone resin prepared by the copolymerization of methyl methacrylate(MMA)and silane coupling agent(KH570)was blended with phosphorous flame retardant regenerated copolyesters PET-11P-x Si with different content of silicone resin was prepared.The results showed that the ultimate oxygen index of the regenerated copolyester was higher than 28.0%and the flame retardant grade was V-0.The total heat release and smoke release of PET-11P-8Si decreased to 63.5 MJ/m~2 and 2802.9 m~2/m~2,respectively,when the silicon-phosphorus content was above 5 wt%.Combined with SEM observation and Raman spectroscopic analysis of the residual carbon morphology,it is found that the dense carbon layer can be formed during the combustion of silica-phosphorus flame retardant regenerated copolyester.The ID/IG ratio of PET-11P-8Si residual carbon decreases from 2.24 to 1.80,and the degree of graphitization increases.The spinnability of silicon-phosphorus flame retardant regenerated coppolyester PET-11P-5Si was investigated by single screw spinning.The surface of PET-11P-5Si monofilament was rough compared with that of the regenerated polyester monofilament and the phosphor flame retardant regenerated coppolyester monofilament was observed by scanning electron microscope.The optical photos of the burning of the monofilament showed that the monofilament was out of fire and the melt drops were zero when ignited.Excellent flame retardant and droplet resistance.