核壳结构纳米TiO2/PMMA/PU复合基耐洗刷涂料的制备

In order to prepare washable WPU coating, two composite emulsions of TiO2/PU and TiO2/PMMA/PU were respectively synthesized by use of silane coupling agent, modified nano TiO2 pre-polymer dispersion and in situ seed polymerization method. The factors that affect the washability of WPU were investigated, such as n(subscript NCO)/n(subscript OH) ratio (R value), the adding processes and content of nano-TiO2, mass ratio of MMA/PU, the type of fillers and functional additives. TEM morphology observation showed that the latex particles of TiO2/PMMA/PU composite emulsion were of core-shell structure with TiO2 as the core. The results showed that the types of the emulsion had a strong impact washability of coatings. The washability of composite emulsion with multilayer core-shell structure was the best and up to 6350 times when nano-TiO2 content and PMMA/PU ratio is respectively 0.5% and 1:4, and the washability of PU coatings can be significantly improved by adding hard flake fillers, micro-fibers and waterproof additives. The washability of PU emulsion coatings could be up to 10000 times by optimizing the formula.