The Preparation And Properties Of Functional Waterborne Polyurethane Coatings

With the progress of science and technology,coatings industry is developing at a high speed,coatings are no longer confined to protection and decoration.With the protection of the environment and energy saving,the traditional coatings have been unable to meet the needs of the people.The new generation of functional and pollution-free waterborne coatings arises at the historic moment.Modification of waterborne polyurethane coatings can give new functions,such as mould proofing,antifouling,sterilization,heat preservation,have become a hot topic in the coatings industry.This article has conducted the research to the preparation of waterborne polyurethane,silica loaded nano silver antibacterial agent,titanium dioxide photocatalyst and the application in the coating.Waterborne polyurethane emulsion was synthesized by acetone self emulsification method of which IPDI,PPG-1000 was used as raw materials,BDO and DMPA were used as hydrophilic chain extenders.The effects of different amounts of raw materials and preparation conditions on polyurethane properties were researched.The results showed that the preparation of waterborne polyurethane emulsion by acetone self emulsification method should strictly control the sealing effect of the reaction device,to prevent the excessive volatilization of acetone.The performance of the emulsion by prepolymerization is superior to one pot method.The optimum ratio of raw materials is R0 1.3,DMPA 6%,BDO 3.5%,EDA 0.054%,H2O 60%.The waterborne polyurethane prepared by this ratio has high solid content,strong water resistance and excellent mechanical properties.Dendritic mesoporous silica microspheres were prepared by sol-gel method with ammonium as catalyst,TEOS as silica source and CTAB as surfactant.Nano Ag was in-situ loaded in the SiO2 microspheres to be antibacterial agent,and it was added to the preparation of waterborne polyurethane.The MIC,MBC and the best amount of addition of the samples were tested by antibacterial examination.The results show that the addition of silane structure promoter and ether are crucial to the formation of dendritic pores.Without ether and silane structural auxiliaries,dendritic channels are difficult to generate.The MIC of nano Ag in the mesoporous silica is between 3.16 mg·L"1 and 3.95 mg·L"1,the MBC is 6.32 mg·L-1.Both of them are superior to pure nano Ag in antibacterial properties.The Ag/SiO2/WPU antibacterial coatings show good antibacterial effect.The best dosage of antiseptic is between 0.6-0.9%.With titanium nitride as a titanium source and concentrated sulfuric acid as solvent,nitrogen doped titanium dioxide was synthesized by hydrothermal method,and it was added to the preparation of waterborne polyurethane.The results showed that the TiO2 were all anatase,nitrogen elements are mostly gap doping,which generated at 140?.The N-TiO2/WPU self cleaning coatings can degrade methylene blue,and have the functions of photocatalytic activity and self cleaning.Through the contact angle test,the best addition amount of N-TiO2 is 0.3%.