The Synthesis Of Hexa(4-aminophenoxy)cyclotriphosphazene And It’s Application As Flame Retardant On Fabric

Development of flame retardant fabric plays a important role in the field of flame retardant research. Traditional ways to produce flame retardant fabric focus on the efficiency, in which flame retardant with halogen and heavy metals are used most often. However, the halogen retardant and heavy metals are commonly considered harmful to human health and the environment. As the increase of the awareness of health and environment of the public,researchers begin to develop some new ways to replace the traditional ways. Phosphazene is a kind of new flame retardant with high content of residual char, outstanding flame retardant properties, and less smoke. Most importantly the phosphazene don’t contain any halogen and heavy metals, and some of the phosphazene with functional group can react with the fiber to improve washing fastness, in line with the flame retardant development trend.In this topic, a kind of phosphazene with special structure was designed. This kind of phosphazene was expected to be with high chemical activity and high affinity to wool fiber and with good anti-dripping property as well as flame retardant property on PET fabric. Firstly the hexa(4-nitrophenoxy) cyclotriphosphazene was synthesized based on the hexachlorocyclotriphosphazene and nitrophenol, then the hexa(4-aminophenoxy)cyclotriphosphazene was obtained by reducing the hexa(4-nitrophenoxy) cyclotriphosphazene under the system of SnCl2 / HCl. The structure of hexa(4-nitrophenoxy) cyclotriphosphazene and hexa(4-aminophenoxy) cyclotriphosphazene was confirmed by elemental analysis, FTIR, 1HNMR, 31P- NMR. The yield of both hexa(4-nitrophenoxy) cyclotriphosphazene and hexa(4-aminophenoxy) cyclotriphosphazene was estimated.Hexa(4-aminophenoxy) cyclotriphosphazene was applied on wool fabric by dipping-padding-curing process to make flame retardant wool fabric. The curing temperature and curing time were discussed, and the optimal curing temperature and curing time is respectively: 140 ℃,3min. Micro-calorimetry, thermal gravimetric analysis, limiting oxygen index, vertical firing test were used to characterize the flame retardant properties of the treated wool fabric. The result showed that hexa(4-aminophenoxy) cyclotriphosphazene can help wool fiber pyrolysis into carbon in advance and decrease the heat release amount, greatly improve limit oxygen index and vertical firing performance. The result of washing test of treated wool fabric showed that the treated wool fabric had excellent durability. As the number of washing increased, the flame retardant properties of treated wool fabric don’t decreased apparently. The limit oxygen index was 42.4% and char length was 0.6 cm after 15 times washing under the best conditon. The char residual morphology of the non-treated wool fabric and the treated wool fabric was analysised by SEM and the resultshowed that the the char residual of treated wool fabric was more loose, porous and thicker than the non-treated one. The structure of treated as well as non-treated wool fabric residual after keeping at different temperature for certain time was analyzed by FTIR and the result showed that treated wool fabric can produce more non-flamable gases during the thermal degradation.Combined with the result of SEM test we concluded that hexa(4-aminophenoxy)cyclotriphosphazene could effectively act as a flame retardant of wool fabric.Hexa(4-aminophenoxy) cyclotriphosphazene was also applied on PET fabric by dipping-padding-curing process to make flame retardant PET fabric. The results of micro calorimetry,thermal gravimetric analysis of treated PET fabric showed that hexa(4-aminophenoxy)cyclotriphosphazene can also decrease the heat release amount greatly of PET fabric and help it pyrolysis into carbon in advance. When the flame retardant concentration was 100g/l(weght gain was 10.1%), the char residual at 600°C(N2atmosphere) of treated PET fabric was 24.4%, higher than that of the non-treated PET fabric(16.97%). SEM was employed to analysis the morphology of non-reated as well as treated PET residual obtained by burning in air. And the result showed that the most of the residual of non-treated PET fabric was melting fluid while the residual of treated PET fabric was char and the char surface was porous and uneven. The result of vertical firing test and limiting oxygen index test showed that hexa(4-aminophenoxy) cyclotriphosphazene performed a good anti-dripping property on PET fabric and can improve the limiting oxygen index slightly, but will decrease the vertical firing level.