| Two-component waterborne polyurethane coating is a friendly paint and had been develop rapidly because of its low film formation temperature, strong adhesion, high hardness and excellent wear and chemical resistance. The coating was made up of isocyanate and polyol and the performance of the film was decided on the later. This thesis was mainly divided into two systems. The first system was acylate and the second system was hybrid of polyester and acrylate system. It worked as follows:(1) The hydroxyl acrylate disperation was prepared by solution polymerization. The molecular weight and the structure of dispersion were characterized by Gel and FTIR.The quantity of hydroxy monomer, carboxyl monomer and nantacid’s kinds which effected the hydroxy acrylate dispersion’s appearance, viscosity and particle size had been researched.Test results showed that the content of the acrylic monomer and the degree of neutralizer affected the water-solubility of the resin. The stronger water-solubility of the resin increased with adding of the acrylic monomer and neutralizer. The suitable content of the methacrylate was 4%-6%. Appropriate content of hydroxyethyl methacrylate was 30%-35%. Suitability neutralizer was N, N-dimethyl and its content was 80%.(2) Two-component waterborne polyurethane film were obtained by curing of HDI-based isocyanate with synthesized hydroxyl acrylate dispersions. The influence of Tg of hydroxyl acrylate dispersion, the ration of NCO/OH and the curing time on the crosslinking density were investigated by Solvent Resistance Test, Swelling Method, Gel Test, FTIR, SEM and DSC respectively. It was found that the Tg of hydroxyl acrylate dispersion took an important role in the determination of the crosslinking density, and the polyurethane with the best crosslinking density was achieved in the ratio of NCO/OH 1.5-2.0 and by the use of hydroxyl acrylate dispersion with Tg of 22℃.(3) The nano materials such as nano-BaSO4, nano-SiO2, nano-Al2O3 were added into two-component waterborne polyurethane to make the nano coating. The way and the quantity of the nano material added would effect the hardness and abrasion resistance of the film which had been proved by pencil hardness test, abrasion resistance test and so on. The hardness test and wear resistance test showed that the wear resistance of the film increased with the nano material’s content. The film would have the best wear resistance when the amount of the nano-SiO2 was 2%-4%. The nano-BaSO4 could enhance the sctratch resistance of the film. When the film was polished 200 times, the gloss of the film unchanged mostly. (4) The 5-SSIPA intermediate was synthesized and the polyester-acrylic hybrid dispersion was preparated with hydrol acylic resin, intermediate and so on. The desage of the intermediate, the temperature of the reaction and the order of adding hydrol acylic resin which affected the stability of the dispersion had been discussed. The Tg and the content of the hydrol acrylic resin which effected the performance of the film had also been researched. Experimental results showed that the content of the intermediates affected the water-soluble of the hybrid resin. Appropriate amount of the intermediate was 12%-16%. The appropriate temperature for preparation hybrid aqueous dispersion was 220℃. Sub-feeding of the acrylic resin could get stability hybrid aqueous dispersion. When the temperature of the hydroxyl resin was 30℃-40℃, the hybrid dispersion had good stability. |
PDF Full Text Request