How to choose titanium dioxide?

How to choose titanium dioxide?

First, the color

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

Second, the hiding power

The optical nature of opacity results from the difference in the refractive index of the pigment and the medium in which it exists. The refractive index of rutile type titanium dioxide is 2.71, and that of anatase type is 2.55, which is the white pigment with the highest hiding power. The covering effect is mainly due to the scattering caused by titanium dioxide, or the absorption caused by the presence of colored substances, or when the intensity of incident light is reduced due to the above two reasons, the covering phenomenon occurs. Therefore, the main reason for determining the hiding power of titanium dioxide is not only the chemical composition and crystal form, but also the particle shape, particle size and particle size distribution of titanium dioxide.

Third, coloring power

Tinting strength is an important characteristic index of titanium dioxide, which is the ability of the mixture to display its own pigment after mixing titanium dioxide with another pigment. That is to say, for a white pigment, after it is mixed with a dark pigment, the lighter the color of the mixture, the stronger its tinting power (color reduction power).

Fourth, oil absorption

Oil absorption is also one of the important pigment properties of titanium dioxide, because it relates to the filling state of titanium dioxide in the vehicle, and can explain its dispersion performance in the medium. In the paint industry, it is used to estimate the consistency of the paint before mixing the paint, guide the formulation of the paint, and preliminarily calculate its pigment volume concentration (pvc).

Fifth, chemical composition

The chemical composition of titanium dioxide determines the chemical properties of titanium dioxide. It is the main sign of the difference between pigments. In addition to reflecting a series of pigment properties of pigments, such as whiteness, color reduction, oil absorption, etc., its application Performance is also very important, such as weather resistance, dispersion and so on.

Sixth, light and weather resistance

The light resistance and weather resistance of titanium dioxide are important indicators to measure the application performance of titanium dioxide, and it is meaningless to refer to its light resistance and weather resistance alone. This indicator is meaningful only after titanium dioxide is applied to related application fields (such as automotive paint, profiles, etc.). Therefore, the light resistance and weather resistance of titanium dioxide refer to its light resistance and weather resistance in a certain field. In addition, to measure the light resistance and weather resistance of titanium dioxide, it is necessary to ensure that the weather resistance of its application carrier is better than that of titanium dioxide. The main factors affecting the weather resistance index of titanium dioxide are its chemical composition, chemical form of coating material, crystal structure, application formula, etc.

Seventh, gloss

The glossiness of titanium dioxide is an important index to measure the application performance of titanium dioxide. Usually titanium dioxide has no luster, and it is meaningless to refer to its gloss alone. This indicator is meaningful only after titanium dioxide is applied to related application fields (such as automotive paint, ink, profile, masterbatch, etc.).

Eighth, volatile matter

The volatile content of titanium dioxide is actually the water content. Because there are high energy and hydroxyl groups on its surface, it is always necessary to absorb a certain amount of water on its surface to reduce its surface energy. The amount of absorbed water is related to the organic treatment of the surface of titanium dioxide and the humidity and temperature of the surrounding environment where it is stored. The volatile content of titanium dioxide cannot determine the quality of the product, it depends on the application system. In general, the volatile content of water-based systems has little effect on the application, but for oil-based systems and polyolefin systems, the lower the volatile content, the better, because high volatile content will affect its dispersion performance in the system and products. quality.

Ninth, dispersion

Dispersion is also known as grinding dispersibility or grinding wettability. When it is used in water as the medium, it is called water dispersibility, and when it is used in solvent and other coating systems, it is called oil dispersibility. Dispersion index is an important application index of titanium dioxide. The quality of dispersibility not only affects the decolorization power, hiding power, oil absorption and other indicators of titanium dioxide pigments, but also affects the gloss and weather resistance of coating film formation or profile molding. When grinding and dispersing in a paint production plant, the quality of the dispersibility directly affects the length of the grinding and dispersing time, which is one of the important economic indicators in the paint production, and if the grinding time is too long, it will also increase the pollution of the equipment and cause the whiteness of the product to change. Difference. In the production of plastic masterbatches or profiles, the quality of dispersibility directly affects the cycle of replacing the head screen and the performance of the final product