The Research On Preparation Of Derivative And Modification Of Waterborne Polyurethane By Tung Oil

Waterborne polyurethane(WPU) has shortcomings of low mechanical strength, poor water and solvent resistance, which seriously hamper the development of it to some extent. So it is necessary to modify the WPU by diverse methods to improve comprehensive performance of film. Tung oil could be modified with derivatization method to prepare waterborne polyurethane because it has the characteristics of quick drying, strong stickiness, efficient water proofing, good endurance for acid and alkali and heat, which not only improved mechanics performance and properties of water and solvent resistant of the WPU, but enhanced the added value of tung oil, and brought good social and economic benefit. Eleostearic acid was synthesized with Tung oil by heterogeneous hydrolysis and then, the appropriate conditions for preparing tung oil monoglyceride(TOM) by chemical group protection method was study. Furthermore, TOM and Tung Oil Anhydride Ester Polyol(TOAEP) were used to prepare TOM modified WPU and TOAEP modified WPU, respectively. The water and solvent resistance, acid and basic resistance, mechanical and therma properties of the films were examined according to GB and then, the preparation technology was optimized on the basis of experimental result. The research results were as follows:1. The appropriate conditions of preparing eleostearic acid were mole ratio of tung oil to KOH1:3.5, reaction time1.5h and reaction temperature70℃, mass ratio of oil to water1:12. Under the optimal conditions, eleostearic acid’s yield was98.4%with acid value168.6mg KOH/g.2. DT-851catalytic resin was fit for the catalysis of solketal condensation reaction, the optimum synthetic conditions were as follows:catalyst sulfonic acid resin dosage5%(wt, calculated by glycerol), mass ratio of glycerol to acetone1:20and refluxing for2h. Solketal’s yield was95.0%under the optimum reaction conditions. The catalyst DT-851resin can be reused six times and has good catalytic activity.3. Xylene was chosen for dehydrating agent, the appropriate conditions of TOM synthesis by chemical group protection method were as follows:mole ratio of solketal to eleostearic acid1.5:1, catalyst p-toluenesulfonic acid dosage5%(wt, calculated by eleostearic acid), reaction temperature70℃and reaction time3h. Under the optimal conditions, the conversion rate on eleostearic acid was99.1%. The product monoglyceride’s yield was93.6%with content of monoglycerides about95.6%by deprotection of4h.4. The appropriate conditions of TOM modified WPU synthesis were:isocyanate index R was1.2, DMPA content was4%, hard segment content was60%, and TOM content was8%. Emulsion particle size, Shore A hardness, tensile strength of the modified WPU increased as the weight content of TOM was increased, as well as water and solvent resistance, acid and basic resistance. The therma property was obviously improved after modification.5. The appropriate conditions of TOAEP modified WPU synthesis were: isocyanate index R was1.2, DMPA content was5%, hard segment content was60%, and TOAEP content was8%. Emulsion particle size, Shore A hardness, tensile strength of the modified WPU increased as the weight content of TOAEP increased, as well as water and solvent resistance, acid and basic resistance. The therma property was improved a lot after modification.The two kinds of modified WPUs from TOM and TOAEP showed good water and solvent resistance, acid and basic resistance, mechanical property and heat resistance. The study could widen the scope of WPU’s application, and enhance the added value of tung oil, furthermore, drive the development of Tung oil processing industry, and bring good social and economic benefit.