Study On The Synthesis Of Organic Phosphorus Flame Retardants And Its Application In Nylon

Nylon are widely used in the industries of electronic communications, textiles, chemical manufacturing and so on with its good mechanical properties and processing properties.However, as a kind of flammable polymer material, nylon is easily cause fire, by adding flame retardant nylon can improve the flame retardancy. In recent years, the environmental protection consciousness of people is strengthened, the material also increasingly stringent flame retardant requirements. Compared with most halogen flame-retardant, phosphorus flame retardants has high efficiency, smoke suppression and non-toxic, halogen-free, etc. Phosphorus-containing flame retardants mainly include adding type and reaction type two kinds, the type of adding phosphorus flame retardant because of the disadvantages of high adding amount and poor compatibility limits its application. Therefore, development of low volatile, high efficiency, good compatibility with matrix, non-toxic reaction type organic phosphorus flame retardants and applied to the nylon is an effective way to improve the flame retardant nylon. In this paper,firstly bis(2-carboxyethyl)phosphinic acid was prepared by hypophosphorous acid, trimethyl orthoformate with acrylonitrile and its chemial structure was characterized and the optimum reaction conditions were obtained. Secendly, bis(2-carboxyethyl)phosphinic acid-Hexanediamine was prepared by aminating bis(2-carboxyethyl)phosphinic acid with hexanediamine, and its chemicalstructure, thermal stability were characterized. Finally, the amination product bis(2-carboxyl ethyl) phosphonic acid- hexamethylenediamine was add to the nylon 66, as a flame retardant monomer to prepare flame retardant nylon 66, and its molecular structure was characterized, and the effect of flame retardant on the thermal stability and flame retardant performance of nylon 66 were studied.The main research results were as following:(1) the optimum reaction conditions of bis(2-carboxyl ethyl) phosphonic acid were as followed: n(hypophosphorous acid):n(trimethylorthoformate)=1.0:1.3, the reaction temperature was 20~30 ℃, the reaction time was 3h and the yield of bis(2- carboxyl ethyl) phosphonic acid was up to 50.79%. The onset decomposition temperature of bis(2- carboxyl ethyl) phosphonic acid was 192 ℃, which couldn’t meet the polymerization temperature requirement of nylon 66.(2) Compared with bis(2- carboxyl ethyl) phosphonic acid, bis(2- carboxyl ethyl) phosphonic acid-hexamethylenediamine had higher thermal stablity, the onset decomposition temperature reached 240 ℃, which could be suitable for polymerization of nylon 66.(3) The structure of bis(2- carboxyl ethyl) phosphonic acid occurred in the molecule chain of FR-PA66 besides the typical structure of PA66, which suggested that bis(2- carboxyl ethyl) phosphonic acid had polymerized in the molecule chain of PA66.(4) The thermal decomposition of FR-PA66 was changed and the residue in 600 ℃ increased. The LOI values were enhanced with the raising addition of bis(2-carboxyl ethyl) phosphonic acid in FR-PA66, indicating that the flame retardant of FR-PA66 was improved.