Factors Affecting The Dispersion of Titanium Dioxide TIO2 in Solvent-based Coatings And Improvement Methods

Titanium dioxide is the main film-forming substance of coatings. It not only makes the surface of the coated object bright and white, but also enhances the weather resistance, anti-powdering ability and rheology of the coating. The dispersibility of titanium dioxide is very important in coatings. Its quality will directly affect the production process, production equipment and product quality of the coating. Understanding the dispersion factors of titanium dioxide in coatings can not only improve the quality of coatings, but also reduce pollution emissions and enable the country's clean industry requirements to be better implemented.

1. Factors affecting dispersion

In solvent-based coatings, once the resin and solvent oil are determined, the application performance and performance characteristics of titanium dioxide determine its dispersion and dispersion stabilization degree.

First, the average particle size and particle size distribution affect the performance of titanium dioxide pigments. When the mass percentage of titanium dioxide particle size is less than 200nm, the Zeta potential is about -70mv. When the mass percentage is less than 20%, the Zeta potential is about -40mv. It can be seen that the particle size of titanium dioxide seriously affects its surface potential. properties, thereby affecting surface adsorption properties. It should be noted that the particle size cannot be too small, otherwise it will affect other properties of titanium dioxide. It is best to control the particle size at (0115~013) Lm.

Secondly, the content of soluble substances affects the application performance of titanium dioxide. In the mixed coating dispersion system, highly polar inorganic ions will not only offset the charge on the titanium dioxide surface, but also fail to form a strong double electric layer, weakening the adsorption effect on the titanium dioxide surface and preventing the resin from being firmly adsorbed on the titanium 

dioxide particles. surface, thereby reducing the degree of dispersion and stabilization of titanium dioxide, causing it to coarsen in solvent-based coatings.

Thirdly, the amount of oil absorption affects the dispersion or dispersion stability of titanium dioxide. After titanium dioxide with a high oil absorption capacity is ground and dispersed, part of the solvent oil will be absorbed by the titanium dioxide, resulting in insufficient oil to dissolve the resin, reducing the degree of resin solvation, weakening the adsorption of titanium dioxide, resulting in reduced dispersion and dispersion stability. .

2. Ways to improve dispersion

First, strictly control particle size and particle size distribution.

The influencing factors of titanium dioxide particle size and particle size distribution are complex and difficult to fully grasp. Therefore, the hydrolysis process and technology can be improved first to ensure that the generated primary particles are uniform. Secondly, the control of the key temperature points of calcination can be strengthened to make the titanium dioxide particles grow evenly. For the final pulverization of the product, a jet mill with high efficiency and good classification effect can be selected instead of the Raymond system to stabilize the surface properties of titanium dioxide.

Second, strictly control the amount of oil absorption and water-soluble substances.

The oil absorption capacity of titanium dioxide is mainly related to the calcining atmosphere or the high temperature of the calcining during the calcining process. Improper control will cause lattice defects and irregular particle shapes of titanium dioxide particles. Therefore, it is necessary to control the appropriate calcining temperature and adjust the feed amount. Reasonable matching with the speed of the kiln body reduces the lattice defects of the particles and the regular geometric shape of the particles.

Third, strictly carry out surface treatment.

At present, most domestic manufacturers produce anatase titanium dioxide, which has poor dispersion in coatings. Under the background of the country's promotion of clean industry, its application in the coatings industry has gradually been replaced by rutile titanium dioxide. For coating companies that are still using anatase titanium dioxide, their surface properties can be changed through surface treatment, such as selecting silicone, coupled nitrogen reagents or some polyphosphates.

Dispersion is an important indicator that titanium dioxide manufacturers are most concerned about. Poor dispersion will not only greatly reduce the efficacy of titanium dioxide, but also intensify pollution. With the rapid development of my country's economy and the increasing improvement of policies, especially environmental protection policies, titanium dioxide-related industries, especially the coating manufacturing industry, are developing rapidly, which has brought unprecedented opportunities and challenges to my country's titanium dioxide manufacturing industry. Therefore, titanium dioxide companies should carefully study product performance, improve production processes in a timely manner, lay a solid foundation, and change national policies from resistance to thrust to achieve a stable take-off of the company.