Study On Synthesis And Application Of 1, 4-Phenylene Dissocyanate

1,4-phenylene diisocyanate (PPDI) is used as raw material of polyurethane elastomer with high performance. At present, the industrial production of PPDI takes phosgene as raw material, which is dangerous and contaminable seriously.1,4-phenylene diamine (PPDA) and bis(trichloromethyl) carbonate (BTC) as the phosgene substitute material has distinct advantages, such as moderate conditions, safe and simple and convenient operation, high yield and good quality, which is easy to be industrialized. The reaction and related process were studied, in addition we had done a performance comparison studies between PPDI and TDI-casting polyurethane elastomer in the thesis.It was identified by IR, MS, 13C NMR melting point tests and the color reaction of-NCO that the objective product of the reaction was PPDI. Based on the principle of chemometrics, the key reactions of the reaction system was analyzed and defined. The result of thermodynamics analysis of the system showed that the secondary-reaction bringing urea competed with the main-reaction, and it was beneficial to the main-reaction increasing temperature. It was found that chlorobenzene was the best select by solubility tests of PPDA. The effects of reaction conditions on the yield of PPDI were discussed. The result showed that reaction temperature, time and molar ratio of raw materials were the main influencing factors. Through the orthogonal designing experiments, optimal reaction conditions were obtained:the reaction temperature is 120℃, the reaction time is 3.5, the mole ratio of PPDA to BTC is 3:3.3, mass fraction of BTC is 100 g-L-1, mass fraction of PPDA is 15 g·L-1 the temperature of drop PPDA is 70℃, velocity of dripping PPDA is 0.13g·min-1. Under optimum conditions the magnesium acetate yield could reach 85.56%.The kinetic equation was performed. The rate of the process may be described by r=ea(CA+b)0.5; a=-3.675 X 10-4T2+0.2901T-67.56; b=0.0014T-0.5547Based on the equation, a set of curve between reaction rate and reaction temperature at different CA, which result showed that when the concentration of PPDA is high;the slope of the curve in the initial stage than the end of the reaction, so the action rate at high concentrations more affected by temperature.The different performace of PPDI and TDI-based polyurethane elastomer were analyzed by TG, DMA and WAXD. The thermal stability and micro-phase separation was inverstigated, which result showed that PPDI-casting polyurethane elastomer has better heat resistance and higher degree of phase separation than TDI-casting polyurethane elastomer.