Study Of Polyurethane Modified By Isocyanate Trimer-Mercapto Siloxane Complex

Polyurethanes(PUs) is a polymer material which has an extensive application, but the pure polyurethanes has some disadvantage such as low mechanical property, low water resistance and harming to environment which restricted its application. Improving combination property has been urgent affairs and introducing rigid structure to PUs has been a primary way to improve its water resistance and mechanical property. Diisocyanate trimers possess isocyanurate rigid structure without active hydrogen atom and have highly thermal stability, hydrolysis stability, strong radiation resistance, yellowing resistance, as well as flame retardancy. These properties are of great significance in polyurethane which offer the products an outstanding practical performance in hardness, water resistance, thermal stability and weather ability. Organosiloxane, with low surface energy, high heat resistance, high strength and good antioxygenic activity, can improve the polyurethanes’water resistance and thermal stability. Therefore, in this thesis, we prepared polyurethanes by introducing isocyanurate with siloxane and anticipated to improve the polyurethanes’combination property. The main research work is shown below:1.Synthetized TDI trimer and TDI trimer-siloxane compound modifided by y-mercaptopropyltriethoxysilane(MPTS) under catalyst. Then, we compared the performance of exopy resin and waterborne polyurethane cured by TDI trimer and modifided TDI trimer.It was found that the modified trimer increased the resins’ performance to some extent.2.Anionic aqueous polyether PU emulsion was prepared by prepolymer mixing process from polyethylene glycol(PEG), glycerol, dimethylolpropionic acid (DMPA), toluene diisocyanate(TDI) and TDI trimer-silixane compound. The effects of R(n-Nco/n-OH) value, DMPA content, PEG molecular weight, silicon content and addition technology of TDI trimer on PU’s properties were investigated. By comparing the performance of pure PU, TDI trimer modified PU and TDI trimer-siloxane complex modified PU, we found that the PU modified by TDI trimer-siloxane complex has the best properties.3.Solvent-based PU was synthesied by solution method using PEG,1,4-butanediol, TDI, TDI trimer-siloxane complex and N,N-dimethylformamide (DMF) as the solvent. The effects of changing solvents, chain-extender, reaction temperature, preparation process and silicon content on PU’s properties were investigated. In addition, we compared the performance of pure PU, TDI trimer modified PU and TDI trimer-siloxane complex modified PU, then we found that the PU modified by TDI trimer-siloxane complex exhibited desirable properties.