Factors Affecting the Dispersion of Titanium
Dioxide in Solvent-based Coatings
Titanium dioxide is a secondary film-forming substance for coatings, which not only makes the surface of the object to be coated bright and white, but also enhances the weather resistance, anti-powdering ability and rheological properties of the coating. The dispersion of titanium dioxide has a direct impact on the production process, production equipment and product quality. Understanding the factors affecting the dispersion of titanium dioxide in coatings will not only improve the quality of coatings, but will also reduce pollution emissions and enable better implementation of national clean industry requirements.
In solvent-based coatings, once the resin and solvent oil have been determined, the application properties and performance characteristics of the titanium dioxide determine the degree of dispersion and dispersion stabilisation of the titanium dioxide.
Firstly, the average particle size and size distribution affects the titanium dioxide pigment performance. When the titanium dioxide particle size of less than 200nm mass percent in about 30%, the zeta potential is about -70mv; if the mass percent is less than 20%, the zeta potential is about -40mv, visible titanium dioxide particle size situation seriously affect its surface electrical properties, thus affecting the surface adsorption performance. It should be noted that the particle size should not be too small, otherwise it will affect the other properties of titanium dioxide, it is best to control the particle size in (0115 ~ 013) Lm.
Secondly, the level of soluble material content affects the application of titanium dioxide performance. In the mixed coating dispersion system, the polarity of very strong inorganic ions will offset the titanium dioxide surface charge, but also can not form a strong double electric layer, so that the adsorption of titanium dioxide surface is weakened, so that the resin can not be firmly adsorbed in the titanium dioxide particle surface, thus reducing the degree of titanium dioxide dispersion stabilization, resulting in its return to coarse in solvent-based coatings.
Thirdly, the level of oil absorption affects titanium dioxide dispersion or dispersion stability. High oil absorption of titanium dioxide grinding dispersion, part of the solvent oil will be absorbed by the titanium dioxide, so that the dissolved resin oil is not enough, the resin solvent degree is reduced, weakening the adsorption of titanium dioxide, resulting in its dispersion and dispersion stability is reduced.
