How to choose titanium dioxide correctly?

First, the color

Color is an important technical indicator for pigments. Titanium dioxide is called "the king of white pigments", and the color index of titanium dioxide is whiteness. Even titanium dioxide of the same chemical composition will produce different colors due to different process routes, raw materials, equipment, and technical level. Although color light depends on chemical composition, the more important and often decisive factor is its Particle shape, size, particle size distribution, crystal form, impurity content, and the like.

Second, opacity

The optical nature of the hiding power is caused by the difference in refractive index between the pigment and the medium surrounding it. The rutile titanium dioxide has a refractive index of 2.71 and an anatase type of 2.55, which is the white pigment with the highest hiding power. The occlusion effect occurs mainly due to scattering caused by titanium dioxide, or absorption due to the presence of a colored substance, or both of the above reasons to reduce the intensity of the incident light. Therefore, in addition to chemical components and crystal forms, the main reason for determining the hiding power of titanium dioxide is related to the particle shape, particle size and particle size distribution of titanium dioxide.

Third, tinting strength

Tinting strength is an important characteristic indicator of titanium dioxide. When titanium dioxide is mixed with another pigment, the ability of the mixture to display its own pigment can be obtained. That is to say, for a white pigment, when it is mixed with a dark pigment, the lighter the color of the mixture, the stronger the coloring power (achromatic power).

Fourth, oil absorption

The oil absorption is also one of the important pigment properties of titanium dioxide, because it involves the filling state of titanium dioxide in the toner, and can explain its dispersion in the medium. In the coatings industry, the consistency of the coating is estimated before the paint is mixed, the formulation of the coating is guided, and the pigment volume concentration (pvc) can be preliminarily estimated.

V. Chemical composition

The chemical composition of titanium dioxide determines the chemical properties of titanium dioxide. It is the main indicator of the difference between pigments. It not only reflects the pigment properties of pigments, such as whiteness, achromatic power, oil absorption, etc. The performance is also very important, such as weather resistance, dispersion and the like.

Sixth, light and weather resistance

The light fastness and weather resistance of titanium dioxide are important indicators for measuring the application performance of titanium dioxide. It is meaningless to refer to its light resistance and weather resistance alone. This indicator is only meaningful if titanium dioxide is applied to the relevant application areas (eg automotive paints, profiles, etc.). Therefore, the light fastness and weather resistance of titanium dioxide refers to its light resistance and weather resistance in a certain field. In addition, the light resistance and weather resistance of titanium dioxide are measured to ensure that the weather resistance of the applied carrier is superior to that of titanium dioxide. The main factors affecting the weatherability index of titanium dioxide include chemical composition, chemical form of the coating material, crystal structure, and application formula.

Seven, gloss

The gloss of titanium dioxide is an important indicator to measure the application performance of titanium dioxide. Usually, titanium dioxide has no luster, and its gloss alone has no meaning. This indicator is only meaningful if titanium dioxide is applied to the relevant application areas (eg automotive paints, inks, profiles, masterbatches, etc.).

Eight, decentralized

Dispersibility, also known as grinding dispersibility or abrasive wettability, is referred to as water dispersibility when used in water as a medium, and is referred to as oil dispersibility when used in a coating system such as a solvent. The dispersity index is an important application index for titanium dioxide. The quality of dispersibility not only affects the decolorizing power, hiding power, oil absorption and other indicators of titanium dioxide pigment, but also affects the gloss and weather resistance of coating film forming or profile forming. When grinding and dispersing in the paint production plant, the dispersibility directly affects the length of the grinding and dispersing time. It is one of the important economic indicators in the production of the coating, and the grinding time is too long, which will increase the equipment pollution and make the product whiteness change. difference. In the production of plastic masterbatch or profile, the dispersibility directly affects the cycle of replacing the head screen and the performance of the final product.

Nine, volatiles

The volatile matter of titanium dioxide is actually the water content. Because of its high energy and hydroxyl groups on the surface, its surface always adsorbs a certain amount of water to reduce its surface energy. The amount of absorbed water is related to the surface organic treatment of titanium dioxide and the humidity and temperature of its surrounding environment. The level of volatiles in titanium dioxide cannot determine the pros and cons of the product, depending on the application system. In general, the fluctuation of the volatile content of the aqueous system has little effect on the application, but for oily systems and polyolefin systems, the lower the volatile content, the better, because the high volatile content will affect its dispersion performance and products in the system. quality.