Optimization Of Synthesis Of Aliphatic Polycarbonate Diols

Polycarbonate diols is a kind of specialty diols as a soft segment of high performance PU,which combined the advantages of Poly(ether urethane) and Poly(ester urethane). The market and application of PCDL was demonstrated,and synthesis process was summarized,from which transesterification methods is regards as the best option with dimethyl carbonate and diol as precursor.A series of PCDLs were synthesized via transesterification of diols and DMC,from which the process parameters such as catalyst and its amount,ratio of reactants,reaction time,reaction temperature and pressure were investigated.The process was estimated with conversion/yield and molecular weight of PCDLs and the product was characterized by FTIR and GPC.The experimental results list as follows:With 0.3% wt of triethylamine as catalyst, reaction ratio of 1.25, reflux time for more than 2h, reaction temperature of 150℃, condensation reaction time and temperature as 2h and 170℃, absolute pressure as 8Kpa, The poly tetramethylene carbonate diols with molecular weight of about 1500 was prepared successfully. With 0.35% wt of triethylamine as catalyst, reaction ratio of 1.25, reaction temperature of 150℃, condensation reaction time and temperature as 2.5h and 175℃, absolute pressure as 7Kpa, The poly hexamethylene carbonate diols with molecular weight of about 1900 was prepared successfully.With 0.4% wt of triethylamine as catalyst, reaction ratio of 1.25, reaction temperature of 160℃, condensation reaction time and temperature as 3.5h and 180℃, absolute pressure as 5Kpa, The Copoly Carbonate Diols with molecular weight of about 1800 was prepared successfully.