The Synthetic Research Of Phosphorus-containing Flame Retardants

With the reinforcement of the safety awareness and environmental protection consciousness, flame retardant materials have to meet more strict demands. Low-smoke, non-halogen and low-toxicity materials become more and more popular. Organic phosphated flame retardant turns out to be the focal material because of its low smoke, low toxicity, high competence of fireproofing and thermal stability. This paper optimizes the processes of oligomeric bisphenol A bis(diphenylphosphate) (BDP) and 2,6,7-trioxa-1-phoshabicyclo[2. 2.2]-octane-4-methano. Furthermore, with PEPA as the starting material, two new types of flame retardants have been synthesised. The major experiment content and conclusions are as follows.(1) The optimized process is:BDP:n (POCl3):n (bisphenol A):n (phenol)= 5.5:1: 4.05; anhydrous MgCl2 as catalyst,1% to 2% of bisphenol A’s quantity; PCI5 as accessory ingredient 1.5%o of bisphenol A’quantity; 3.5 hours for condensation reaction and 6 hours for endcapping reaction. During the post-processing, the BDP rude product is dissolved in the mixed solvent of toluene and cyclohexane (1:1) first, then is washed with 1% citric acid solution and 4% NaOH solution. Following this route, the yield is 86.8% and the content of the BDP monomer is 86.96%.(2) Synthetic process of PEPA is:n (POCI3):n (pentaerythritol)=1.04:1; V (dioxane): V (1,2-dichloropropane)= 3:1, dry dioxane before use. After a dropping of POCl3 for 3.5 hours at 84-88℃is a reaction of 6 hours at 93-95℃. According this synthesis route line, the yield of PEPA was 95.1%.(3) Two types of flame retardants are synthesized by using PEPA as starting material. Their structures and purities are confirmed by IR,’HNMR. TGA shows that the two new flame retardants have good thermal stability and good performance of carbonization.