Study On Ring Opening Polymerization Of Propylene Carbonate And Preparation Of Waterborne Polyurethane Emulsion

PPC is a kind of material with excellent environmental protection performance.At present,few studies on the synthesis of polycarbonate polyols by ring opening polymerization were reported.In this paper,PPC was prepared by ring opening polymerization used PC as monomer and diethylene glycol as initiator by the catalysis of sodium stannate,which provides a novel method to synthesize polycarbonate polyols.Meanwhile,waterborne polyurethane(WPU)from PPC and TDI,WPU waterproof coatings and WPU wood coatings were prepared and characterized.The main results are as follows:The study on the ring opening polymerization of propylene carbonate shows that:(1)with the increase of monomer / initiator ratio,the higher the molecular weight of the product,the narrower the molecular weight distribution.(2)The best ammount of the catalyst is 0.3%-0.5%.(3)The optimum reaction conditions are obtained by the orthogonal experiment: reaction temperature 210 ℃,reaction time 14 h,sodium stannate 0.3wt%,propylene carbonate and diethylene glycol 100:1.The research on the WPU waterproof coating shows that:(1)the tensile strength and adhesive strength of the film shows peak value with increasing the content of HDI,and the addition of HDI increases the water resistance.(2)With the increase of the hard segment content,the tensile strength of the film increases gradually,companied by the significant decreasing of the elongation at break.(3)compared to the other fillers selected in this experiment,the WPU waterproof coating with nano silica as filler shows better comprehensive performance.(4)the formulation of the WPU waterproof coating is optimized by orthogonal experiment,and the formulation is obtained All of them can reach the national standard.The research on the WPU wood paint shows that:(1)with the increase of the IPDI content,the particle size of the emulsion tends to be small,and the appearance of the emulsion is more transparent and the emulsion is more stable.The hardness of the paint film without adding IPDI wood lacquer is inferior.However,when the IPDI content is more than 15%,the water and alcohol resistance decrease.(2)Chain extender couldimprove the gloss,hardness,water and alcohol resistance of the film by the inner crosslinking,among which BDO and TMP are the optimum.The chain extender process was discussed and the reaction conditions were optimized.(3)Compared to the other polyols selected in this experiment,the hardness of WPU wood paint used polycarbonate as the soft segment is more superior.(4)The formulation of the wood paint was optimized by the orthogonal experiment.The optimized WPU wood paint has high gloss,and excellent adhesion,water resistance and comprehensive performance.