| WPU is a macromolecule material, and VOC substitued by water is used as a dispersed medium.This dope hardly contain VOC, which has many merits,such as innocuity, not easy flammability, not poluting environment, saving energy, safety, easy operation etc. In recent years, people pay more and more attention to the environment friendly water-based polyurethane which has excellent performance. Polyurethane paint has been gradually developing from solvent paint into water-based polyurethane in the world. In this dissertation, the synthesis and modification of waterborne polyurethane resins by self emulsification and its relative properties were studied. It consists of three parts.First, the waterborne cationic polyurethane modified by epoxy resin was studied. We discussed some problems as following. The effects of process variables such as blocking agent,epoxy resin, MDEA, diisocyanates, polyols, R (NCO/OH) on the properties of paint film were researched.The effects of the different solvents and aid agent on the properties of paint film were researched. The effect of the neutralization degree on the parameters of emulsion and the property of film was researched. The effect of the roast time on the property of film at 150℃was researched. The effect of the solid content on the viscosity of emulsion and the thickness of paint film was researched.The result showed that HEMA/MEKO used as the blocking agent was better than MEKO,DMP.The thickness and hardness of film could be improved with increasing the EP content. The appearance of film and lied on the MDEA content. The hardness of film became hard with increasing R.The performance of electrophoretic film synthesized by IPDI/MDI and polyester were better than other raw material.The better apperance of film could be got by using BCS,NB and 1,4-Dioxane. The thickness of film could be improved by ppH.The property of film could be improved by using 0.4% Aiex 4552. The stable emulsion and better appearance of film were got when the neutralization was 100%.The property of film was best when the roast time was 30-40min at 150℃.When the content of emulsion was lower, the viscosity of emulsion hardly changed with increasing the solid content,but the appearance of film changed greatly.When the solid content was 22%, the coarse appearance of film could appear.Second, the waterborne anode polyurethane modified by epoxy resin was studied. We studied some problems as following. The effect of the DMPA content on the emulsion and viscosity was researched. The effects of the different types polyols with the same molecular weight and the different molecular weight with the same polyol on the property of paint film were researched. The effects of the epoxy resin E-12,E-44 and the admixture of E-12\E-44 on the property of paint film were researched. The effects of the types and content of aid agent on the property of paint film were researched. The effects of the electrophoresis time and the emulsion temperature on the thickness of film were researched. The relationship between current and electrophoresis time was researched,and the best roast process was found.The result showed that the better stable emulsion and the smaller particle were got with increasing the DMPA content. The polyester had better water resistance than polyaether with the same molecular weight. The higher molecular weight, the better water resistance with the same polyester. The resin modified by 13.6% E-12 had the best property. The thickness of film was 24-25.2μm when the electrophoresis time was 30-50s. The thickness of film became smaller when the emulsion was higher. The better property of film could be got when the dry roast route of the beginning temperature was 20℃,and settled 30min at 50℃.Third, the cationic UV cured polyurethane modified epoxy resin blocked by HEMA was prepared. We studied some problems as following. The effect of the CO content on the property of paint film was researched. The effect of the different blocking agent content on the property of paint film and Tg was researched. The effect of the dry temperature on the final gloss degree of film was researched. The effect of the different types and content of solicitation agent on the appearance of film were researched. The effect of the illumination time on the appearance of paint film and water resistance was researched. The result showed that the erosion resistance could be improved with increasing the castor oil content. With the HEMA content increasing,Tg could be enhanced, the tension strength could be augmented and the rupture elongation ratio could be minished. The gloss degree of film was best when the illumination time was 3-4min and the dry time were 20min at 110℃. When the benzoin ethyl ether content was 0.4% and the illumination was 3-4 min, the property of film was best.
|
PDF Full Text Request