Study On Waterborne Polyurethane Based On PET Oligomer/Castor Oil Blended Polyol And Its Properties

Waterborne polyurethane(WPU)has excellent wear resistance,yellowing resistance and film-forming properties,and has excellent adhesion fastness on the surface of printing substrates,and has good dispersion and wetting ability to pigments.Therefore,WPU can be used as a binder for inks.The ink layer of waterborne polyurethane ink shows good impact resistance,water resistance,flexibility and friction resistance,so it is widely used in the printing and packaging industry.However,most of the soft segments of WPU on the market still use petroleum-based polyols as raw materials,and the increasingly serious oil crisis will affect the supply of raw materials for the polyurethane industry.With the promulgation of environmental legislation and the increasing awareness of environmental protection,the development and utilization of waste resources and vegetable oil resources instead of petroleum resources to produce polyols to prepare polyurethane has received more and more attention.The purpose of this project is to use the solid degradation products(GOPs)of waste PET plastic bottles and castor oil(CO)to completely replace petroleum-based polyols to synthesize WPU,and further prepare environmentally friendly waterborne polyurethane inks to reduce the consumption of petroleum resources,improve the recycling value of waste PET plastic bottles,and increase the utilization rate of non-edible castor oil.The specific work contents and main conclusions are as follows:(1)The method of preparing WPU by blending GOPs and castor oil as soft segments was proposed.The possibility of GOPs as soft segments of WPU was explored.The effects of GOPs content on the molecular structure,microstructure and thermodynamic properties of WPU were analyzed.The results showed that GOPs could be used as the soft segment of WPU.The introduction of an appropriate amount of GOPs could make WPU obtain a flatter and denser surface morphology,and GOPs didn’t affect the nanosphere of WPU.GOPs were beneficial for WPU to obtain smaller particle size and narrower particle size distribution.With the increase of GOPs content,the thermal stability of the films were improved,and the decomposition temperature of WPU4 was the highest,up to 395.4℃.DMA showed that the introduction of GOPs could make WPU have higher elasticity and the material could withstand greater stress.The tensile test results showed that the tensile strength of WPU2 was the highest,2.39 MPa,which was 1.73 times that of WPU1 without GOPs.In addition,the introduction of GOPs increased the elongation at break of WPU film,which can improve the ductility of WPU.(2)A method for modifying GOPs/castor oil-based waterborne polyurethane(KWPU)by silane coupling agent was proposed.The effects of KH550 content on the molecular structure,microstructure,thermodynamic properties and water resistance of KWPU films were analyzed.The results showed that KH550 was successfully grafted onto the KWPU molecular chain.GPC showed that KH550 increased the molecular weight of KWPU,and when the addition amount of KH550 was 2%,4%and 6%,the molecular weight distribution of KWPU became narrower,and polyurethane with more uniform polymer chain size could be obtained.Thermogravimetric data showed that the introduction of KH550 improved the heat resistance of KWPU films.The tensile test showed that KH550 could improve the tensile strength and elongation at break of WPU.The tensile strength of KWPU-2%was the highest,4.2 MPa,which was 1.75 times of that before modification.With the increase of KH550,the water resistance of KWPU films were increased,and the contact angle of KH550-8%film was the largest,which was 120°.(3)A method was proposed to synthesize waterborne polyurethane screen printing ink using KWPU as the connecting material and carbon black/Dadan yellow/basic magenta/titanium cyanine blue as pigments.The results showed that KWPU can be mixed with various pigments to prepare color inks.The dispersion state of carbon black in KWPU was excellent,and the ink layer thickness,ink fineness and initial dryness met the relevant standards.The color difference results showed that the printing ink layer of ink 1 on PET and coated paper substrates was uniform.The adhesion and wear resistance of the two inks on PET substrate were greater than those on coated paper substrate,and the performance of ink 1 on PET substrate was the best.The waste-based waterborne polyurethane ink synthesized in this study has excellent water resistance and can be applied to product packaging that requires high water resistance and high mechanical strength.