Study On Self-cleaning Coating Of Titanium Dioxide On Polyurethane Material

Titania has the properties of innocuity, low price, stability, high photocatalytic activity, etc. So TiO2 was used as self-cleaning material for its properties, and it has become the research hotspot. The self-cleaning materials which are formed through spreading TiO2 composite coating on the surface of polyurethane were studied. And the method of self-cleaning characterization was established. With this method, the results of self-cleaning materials prepared were characterized.The influence of the particle diameter and crystal form on photocatalysis of self-cleaning material systems in water or in polyurethane were studied. The results show that relative small particle diameter and anatase TiO2 prompted photocatalysis effect in water, and in polyurethane self-cleaning material systems the particle diameter is not the smaller the better, and the optimum range of particle diameter is 150-200nm. Studies show that the self-cleaning effect turned better when adding zinc acetate to TiO2. The optimum content of zinc acetate is 6wt%. Considering the self-cleaning effect and aspect of the material, the best content of TiO2 in self-cleaning material systems is 7wt%. The effect of phosphoric acid on TiO2 photochromism was studied. The best content of phosphoric acid is 20wt%. Then, the dispersion of nanometer TiO2 in self-cleaning materials were studied. The kind and quantity of dispersants and the adding method could change the stability of nanometer TiO2 self-cleaning emulsion. Dispersion of the self-cleaning materials was characterized by GALEN-III/CTV biology microscope. The results show that the best condition for dispersion is 3% 912# dispersant and 7wt% nanometer TiO2 particles to polyurethane systems, stiring 5min.The polyurethane self-cleaning materials with anatase crystal form nanometer TiO2 were prepared, choosing methylthionine chloride alcohol solution and oil-soluble dye S-BL as contaminants. The effect of polyurethane self-cleaning materials on methylthionine chloride achieved 75%, for oil-soluble dye S-BL achieved 40%, using ultraviolet light(125W) to illuminate for 30min at a hight of 30cm.From the result of pilot-scale experiment for polyurethane self-cleaning materials, it can conclude that the polyurethane materials have the self-cleaning capacity. The physical and chemical properties of the polyurethane self-cleaning materials were tested. And the tensile strength and avulsing property of polyurethane self-cleaning material were unchanged by self-cleaning emulsion coating on the surface of polyurethane, but the light transmittance was lowered slightly. The self-cleaning capacity of the polyurethane self-cleaning materials is better than other con-generic products.