Research On The Powders Of Forming TiO₂ On The Surface Of Kaolin Particle

The titanium dioxide is the best performance and the most widely used white pigment, which is applied to paint, enamel, paper, plastic, rubber, cosmetics and other industries. In the production and consumption of the titanium dioxide, there are some problems, such as huge consumption of resources, serious environmental pollution, high costs in manufacturing, quick growth in demand and the high cost of applications, so the important way to solve the problem is preparation of the low-cost substitutes which have the nature of titanium dioxide. Domestic substitutes for titanium dioxide have obtained a certain amount of research results, but they are still at an early stage, and the main problems are low product whiteness, high oil absorption and low hiding power.Natural non-metallic minerals are ideal TiO₂ carrier, the use of specific technology can fix TiO₂ at the mineral surface, then forming nano-crystal film, and low cost. This experiment is using chemical coprecipitation, which is based on Kaolin for the substrate; sulfuric acid titanium chemical precipitation reaction metatitanic acid which is precipitated in the kaolin, and then drying, filtering, calcining and finally Kaolin coated TiO₂ composite powders can be gained.Study is using XRD, TEM, SEM, TG-DTA, UV and other means of characterization, X-ray diffraction pattern showed that Kaolin / TiO₂ composite powder surface is mainly anatase titanium dioxide. TEM electron microscopy shows, by coating the surface of kaolin particles attached to a layer of dense, homogeneous nano-scale titanium dioxide particles, which can be thought a film structure. UV-Vis spectrophotometer is testing the light transmission of the composite powders, which is near Dioxide.Tests found that the main factors of impacts on Kaolin/TiO₂ dioxide-coated composite powders: suspension concentration, hydrolysis temperature, hydrolysis time, pH, calcination temperature. The results show that: by the chemical coprecipitation preparing Kaolin / TiO₂ composite powder ,the optimum conditions are Titanium sulfate dosage 25%, urea dosage 63%, kaolin dosage 9%, Sodium Hexametaphosphate 3%, kaolin suspensions 5% concentration, hydrolysis temperature of 80℃, reaction time 3h, pH value of 2.0, calcination temperature 600℃, calcination time 2h. As a result of testing, the whiteness of prepared composite powders is from original ore 's 88.0% to 94.2% ,and particle sizes are in the tens of nanometers. In this paper, the experiment was first introduced a carbon black as composite powder additives to improve the dispersion effect.