Synthesisand Propertiesof Soybean Oil-Latic Based Waterbonre Polyurethane Emusion

Polyurethanes (PUs) are one of the most important polymeric materials which are widely used in daily commodity and industrial fields. Solvent-based polyurethanesis the main player in this field and the essential problem of solvent-based products caused by volatile organic solvent was environment pollution, and it cannot meet the development trend of green and increasingly stringent laws and regulations. Therefore,solvent-based polyurethane is gradually replaced by waterborne polyurethane, and it is regarded as the hotspot of development and research.In recent years, with the increasing demand for functional materials and environmental protection, research and development for new polyurethane materials was focused. On one hand, some renewable raw materials were chosen to prepare the polyurethane, such as the vegetable oil-based polyols.On the other hand, the heat resistance, mechanical properties of PU polymers are not satisfying enough, methods such as copolymerization, polycondensation and changing raw materials are used to achieve better performance.In this research, the soybean oil-based polyurethane dispersions was prepared by soybean oil polyols with certain amount of hydroxyl value (via epoxidation-ring opening reaction process),soybean-latic polyols with the same amount of hydroxyl value with soybean oil polyols (via latic-ring opening reaction process),Isophorone diisocyanate (IPDI),2,2-dihydroxymethyl, propionic acid(DMPA) and triethylamine (TEA) by a self-emulsifyingapproach. Firstly, with the combination of orthogonal and single factor experiments, it was found that the epoxidized soybean oil with the epoxy value of4.4%was prepared as controlling m (soybean oil):m (hydrogen peroxide):m (formic acid)=1:0.6:0.4, reaction for24h, the reaction temperature at60℃,for the soybean oil polyols under the conditions of m(epoxidized soybean oil):m (methanol):m (fluoborate)=1:2:0.01, and2h of reaction time, the reaction temperature at50℃and for thesoybean-latic polyols under the conditions of m (epoxidized soybeanoil):m (latic)=1:0.6, the reaction time is16h,the reaction temperature at90℃. Secondly, the influential factors on emulsion viscosity and latexes particle size were considered and found the preparation was the neutralization degree of100%, the R value of1.2and DMPA content of6%wt.Through experiments, emulsion polymerization is an effective method to obtain the SPU and LA-SPU hybrid latexes. FT-IR spectrum analysis confirmed that the polymers are successfully synthesised. With the TEM images, a clear particle was observed with average particle size of82nm and100nm.With the introduction of latic, the thermal stability of the LA-SPU coating was improved greatly.T25increased from285℃to301℃, Tmax increased from355℃to414℃and the thermal decomposition periods change from2to3. This is because the interaction between soft segments and hard segments changes, the enhanced crosslinking and molecular attraction between macromolecular chain strength the microphase separation which could be seen from the difference from Tg1and Tg2.Moreover, upon increasing content of latic,the tensile strength of the coating gradually increases, while the elongation decreases. For the SPU and LA-SPU polymers, When thehydroxyl value becomes140mgKOH/g, the tensile strength grows from1.47MPa to5.75MPa, and the corresponding elongation reduces from to250to153%. Introduction of latic in the latex film formation process will increase the extent of chain entanglement and strength the intermolecular attraction between molecular chain, resulting in better film toughness and tensile strength.