| Comparing with halogen flame retardant, Halogen-free intumescent flame retardants give off less poisonous and corrosion gas to environment, which are welcomed in flame retardant field and will become one developping direction in retardant material. Based on the background we come up with applying wide ranged raw materials to prepare flame retardant with higher phosphorus content. Synthesis of organic phosphorus flame retardants undermentioned not only has filled the blankness in flame retardant field, but also initiated new way for synthesis and application of heat-resistant phosphorus flame retardants. Therefore, it has important theory and operation significance.Five novel caged bicyclic phosphate flame retardants——arylenes bis{di (1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-methylene) phosphate} were designed and synthesized from 1-oxo-4-hydroxymethyl-2,6,7-trioxal-phosphabicyclo- [2.2.2]octane(PEPA) by two steps. The preparation procedure is as follows. PEPA reacted with phophorus oxychloride first gained an pure important media compound di(1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-methylene)chorophosphate, then, the media compound reacted with resorcinol gained resorcinol bis{di (1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-methylene) phosphate}[RTP]. BATP,BSTP,PATP and NTP ramifications of RTP also were synthesized using bisphenol A, bisphenol S, metaphenylene diamine and neopentyl glycol to replace resorcinol respectively. Their structures were characterized by elemental analysis, FT-IR, 1HNMR and MS. Test sesults have been shown that they are dusty solid and participate of high phosphorus. For example, the phosphorus content of RTP is as high as 20.24%.TG analysis shows that the thermal stability and carbonization of RTP, BATP and BSTP is good. The thermal decomposition temperature(lost weight 5%) of them is more than 350℃and the residue for instance of RTP is as high as 57.6% at 600℃. It is prospective that the thermal characteristic aforementioned can catalyze RTP, BATP or BSTP into good flame retardancy for engineering plastic.Because the yields of the compouds are low using the way above-mentioned, we raised one-pot method to synthesize compound resorcinol bis di (1-oxo -2,6,7 -trioxa -1-phosphabicyclo[2.2.2]octane-methylene)Phosphate(RTP), bisphenol A bis di(1-oxo -2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-methylene) Phosphate(BATP) and bisphenol S bis di(1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-methylene) Phosphate (BSTP). First resorsinol, bisphenol A or bisphenol S reacted with superfluous posphorus oxychlorid using aluminium chloride as catalyst. The unreacted phosphrous oxyhalide is removed by distilling under reduced pressure to get intermediate. The intermediate reacted with PEPA using organic base as acid-acceptor. The general yield of RTP, BATP and BSTP preponderate over 80%. FT-IR, 1H NMR and TG analysis show that the structures of flame retardant synthesized by two methods abocementioned is little different which cannot impact the capability of flame retardants.Flame retarded epoxy resin(EP) was prepared using RTP, BATP and BSTP as additive flame retardant. It has been found that addition of flame retardant don't affect EP curing reaction. The experimental results show that the flame retardancy of EP flame-retarded with about 14% of RTP, BATP or BSTP reches UL 94 V-1 grade. By the combination analysis of pyrolysis residue at different temperature from FT-IR and XPS, it is discovered that the framework of flame retardant EP is almost not changed. The decomposed process of flame retardant EP was occured chiefly about 350℃～400℃. Flame retarded char layer which can obstruct the transmission of substance and energy may be formed by decompose, transesterification and phosphoracylation reacton etc. it has been found that the flame retardancy of flame retardant in EP worked in condensed phase.
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