Study On The Flame Retardancy Of Hexamidocyclotriphosphatriazatriene And Its Derivative In Paper

There were plenty of flame retardants used to paper and its products, but most of them had some defects. For phosphonitrile had no halogen, less smoke when burning, high flame retardant efficiency, none toxic and corrosive gas, etc, it was considered as the focus of flame retardants in the future. Hexamidocyclotriphosphatriazatriene (HACTP) and hexahydroxymethylamidocyclo-triphosphazene (HHMAPT) were the early commercial flame retardants, which have good flame retardancy used in the textile fiber. But we can hardly find the report about their using in paper. Therefore, study on their flame retardancy in paper have important theoretical and practical significance on the developing of high performance flame retardant paper.The experimental results showed that HHMAPT have good flame retardancy in paper when HHMAPT additive concentration was 4.5%, limited oxygen index (LOI) reached to 34.9%, the level of flame retardant was fire-retardant grade. Compared to none flame retardant board, after using HHMAPT, the heat release rate increased in a comparatively gradual manner, quality loss became slowly, the time required for complete combustion prolonged, the highest heat release rate, and total heat release decreased significantly with increasing of HHMAPT.The experimental results showed that HHMAPT had a good flame retardancy on the softwood board. The LOI of none flame retardant board was 22.1%, and the level of flame retardant was flammable grade. But when the loading of HHMAPT was 4.5% based on the total weight of the composite, the LOI of the flame retardant paper could be up to 34.9% and the paper belonged to the grade with difficulty to burn. The maximum heat release rate, MHRR average heat release rate, average effective heat (AEHC) and total heat release of combustion of the flame retarded paper reduced significantly, and the mass reduced slowly, the heat release rate increased in a comparatively gradual manner, the time required for ignition and complete combustion was increased compared to non-flame-retardant cardboard, which was more obvious when the amount of HHMAPT increased. Flame retardant cardboard with it also has a small carbonized in a fire area, no residual flame, no smoldering, but not washable. However, the paper composited with HHMAPT and hexamethoxymethylmelamine resin(HMMM) had strong water resistance. When the amount of HHMAPT and HMMM was up to 6% and 10% respectively, the LOI of the washed paper was greater than 33.5% and at the level of flame retardant. Meanwhile, afterflame time and the average carbonized length was less than 4.8s and 12 mm respectively, and the ignition time 0s, through the vertical burn test. The maximum heat release rate, average heat release rate (MHRR), average effective heat (AEHC) and total heat release of combustion of the flame retarded paper reduced, and the mass reduced slowly, the heat release rate increased in a comparatively gradual manner, compared to non-flame-retardant cardboard. HACTP had good fire retardant effect on the softwood board, and prepared with a washable flame-retardant paper. When the flame retardant additive concentration was 6%, LOI was greater than 60%, and After washing, LOI was still up to 39.0%, the level of flame retardant was also flammable grade, fully meet the requirements of washable flame-retardant paper. The maximum heat release rate, MHRR average heat release rate, AEHC average effective heat and total heat release of combustion of the flame retarded paper reduced significantly, and the mass reduced slowly, the heat release rate increased in a comparatively gradual manner, the time required for ignition and complete combustion was increased compared to non-flame-retardant cardboard, which was more obvious when the amount of HACTP increased. After washing, change of heat release rate and quality became slowly, the maximum heat release rate, MHRR average heat release rate AEHC average effective heat and total heat release of combustion increased significantly, but still under non-flame-retardant cardboard.The results of thermo gravimetric analysis and residue analysis showed that HHMAPT and HHMAPT/HMMM having flame retardant effect was mainly through condensed phase. Phosphoric acid-based compound formed by HHMAPT pyrolysis promotes carbonization of cardboard, the expandable char layer was formed under the foaming action of CO2, NH3 and other inert gases,which produced by the decomposition of cardboard and HHMAPT. the carbon layer had flame retardant effect by heat insulation, cutting offoxygen and preventing the volatilization of cardboard decomposition production. The flame-retardant mechanism of HACTP was similar with HHMAPT, except that part of the decompositfon production of HACTP volatiles to the gas phase, by capturing the radicals produced by the combustion flame.The results of paper strength measurement showed that flame-retardant paper prepared with HHMAPT, with the amount of HHMAPT increased, the number of paper folding and tensile index decreased, tearing paper slightly increased, on the whole, compared to the original paper, mechanical properties of flame retardant paper decreased slightly. Flame retardant paper obtained with HHMAPT/HMMM was similar with only adding HHMAPT.While after washing, the number of folding tearing and tensile index increased significantly. The number of folding, tear and tensile index of unwashed and washed flame-retardant paper obtained with HACTP decreased, the mechanical properties also decreased, compared with the paper.