| Mica pearlescent pigments are now more and more widely used as they endow objects with close to nature resplendent pearlescent luster and deeply three-dimensional space character by means of sunlight irradiation, together with their other excellent capabilities, such as chemical resistance, abundance of color and innocuity. The home market is now increasing at a speed of 30%. However, the quality of mica pearlescent pigments produced inland is not so good as that of products imported. It still exists many problems. For example, the pearlescent luster is faint, the color is not pure and the wetting performance and disperse capability is goodish. These questions are also the hotspot and difficulty that in face of producers in China.In the experiment of our project, we chose the mica imported from India as our raw material, which is usually used to produce mica pearlescent pigments. In our experiment, the chemical liquor deposit method is selected because it is the common used one by domestic manufacturers. We improved the pigments' pearlescent luster and color purity by exploring and consummating the production flow, mastering technical factors which affect the quality of products more and adjusting the parameters of these factors.We first grope for the influence factors of the preparation craft before plating which could affect the pearlescent luster of the final products. We decided to add to several preparation technics: calcining ahead of plating, alkaline wash, sour wash and subtly classification. Further more, the optical condition is assured. Calcining under a temperature of 850℃, washing for 20mins under fast stir at 80 ℃ by 20% sodium carbonate solution and washing for 30mins by 12% hydrochloric acid solution at a temperature of 80 ℃ is the best parameter. The results showed that the average reflectivity and the whiteness of the final products is heightened by 10.71% and 10.14% respectively under the effect of preparation technics.Through the mastering of the critical craft of the influence factor, which isthe plating technics, we found the optical parameter of this craft is that the pH value is 1.5, the reaction temperature is 80*C, the prime concentration of titanium tetrachloride solution is 10%, the stirring rate is 240-300 r/min and the dropping rate of titanium tetrachloride solution is 0.3ml/min.In order to improve the production's luster, the crystal of titanium dioxide on the surface of mica powder was transformed from anatase to rutile, because the latter one has the higher refractive index. Three different transformation agents was used and cooperated in the experiments to heighten the transformation rate. We got the preferable quality of the final production when the three agents were used together and the ratio of the four oxide is 3:1:4:20.The factors which influence the whiteness and luster of the final production are investigated through the exploring test. We found that using program control system to control the calcining temperature and verifying the increasing rate of temperature according to the chemical reaction process could commendably advance the quality.We also discussed the composite mechanism of the deposit procedure and conclude that at the initial stages of hydrolyze reaction, the ions of [Ti(H2O)6]4+ combined the surface of mica under the effect of characteristic adoption of pair of electricity layer. In the upper stages, they combined by the effect of physical adoption and chemical adoption together. Thus, the crystal of titanium dioxide came into being and developed.
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