Study On The Synthesis And Properties Of Waterborne Polyurethane Modified With Silicone And Castor Oil

Waterborne polyurethane (WPU) is a binary colloidal system in whichpolyurethane (PU) particles are dispersed in a continuous aqueous phase, and it hasall properties of PU. Recently, WPU has been used in various industrial purposesbecause of its properties of non-toxic, environmental friendly, energy efficiencyand easy operation. In order to enhance the stability of the WPU emulsion, thesystem introduces a hydrophilic group, which causes its poor water resistance, poorwet rubbing fastness and adhesion to the substrate and seriously limits thedevelopment of WPU. Castor oil (CO) is renewable and cheap, and silicone has theproperties of low surface energy and good adhesion. In this paper, CO and siliconewere used to modify WPU to improve water resistance and wet rubbing fastness.WPU emulsion was synthesized with polyether diol (N220and N240) andisophorone diisocyanate (IPDI) as main raw materials, dimethylolpropionic acid(DMPA) as hydrophilic chain extender, trimethylolpropane (TMP) as cross linker,triethylamine (TEA) as neutralizer, hydrazine hydrate and diethylene triamine(DETA) as complex chain extenders. The effects of different components on theparticle size, viscosity, stability of the emulsion and the water-uptake andmechanical properties of the film were discussed. Then the proper synthesiscondition was obtained. The results showed that, the optimized synthesis conditionof WPU was reached when R-value was1.4, the amount of TMP was0.3%to0.5%,and the amount of DMPA was4%.Based on the optimized synthesis condition of WPU, CO and silicone wereused to synthesize modified WPU. The effects of types of silicone on properties ofWPU were investigated; KH-550was selected as the proper modifier. The effects ofthe adding methods and amount of KH-550and the amount of CO on properties ofemulsion and film were discussed. The results showed that, it’s better to addKH-550into the system after emulsification; with the increasing amount of CO, theparticle size and the viscosity of emulsion increased, the water absorption andelongation at break of film decreased, and the tensile strength of film increased atfirst,when the amount of CO was over7%, it decreased; with the increasingamount of KH-550, the particle size of emulsion and the surface contact angle of film increased, the stability of emulsion and the elongation at break decreased,when the amount of KH-550was4%, the water-uptake was the minimum and thetensile strength was the maximum. Thermal gravimetric analysis (TG) and Fouriertransforms infrared spectroscopy （FT-IR） were used to characterize the heatresistance and molecular structure of WPU. TG result indicated that the heatresistance of modified WPU improved obviously，and FT-IR result indicated thatKH-550was grafted on the PU chain successfully.Modified WPU was applied on pigment printing, and the pigment printingproperties were tested. The result indicated that, with the modified WPU asadhesive of pigment printing, dry rubbing fastness was level4～5, wet rubbingfastness was level4, soaping fastness was level5, and the fabric was soft when themass ratio of N220and N240was2:1, the amount of TMP, CO and KH-550were0.5%,5%and4%respectively.