Application of Titanium Dioxide in Coatings

Titanium dioxide is called a white pigment. It has the characteristics of high refractive index, strong achromatic power, large hiding power, good dispersibility, high whiteness, and non-toxicity. It is widely used in coatings, plastics, inks, papermaking, chemical fibers, ceramics, etc. industry. Among them, the largest amount of coating is used, accounting for about 57% of the total titanium dioxide.

Coatings made of titanium dioxide have bright colors, high hiding power, strong tinting power, low dosage, and many varieties. They protect the stability of the medium, enhance the mechanical strength and adhesion of the paint film, prevent cracks, and protect against ultraviolet rays. and moisture penetration, extending the life of the paint film. The color matching of almost every pattern in colorful pattern paints is inseparable from titanium dioxide.

Titanium dioxide is the most commonly used white pigment in coatings. Its output accounts for more than 70% of inorganic pigments, and its consumption accounts for 95.5% of the total consumption of white pigments. At present, about 60% of the world's titanium dioxide is used to make various coatings, especially rutile titanium dioxide, most of which is consumed by the coatings industry.

(1) Water-based paint

Water-based coatings refer to coatings in which most of the volatile substances in the coating formula are water. With the enhancement of people's environmental awareness and the increasingly stringent environmental regulations, water-based coatings have become popular. Like solvent-based coatings, titanium dioxide is required to have good whiteness and dispersion, high hiding power, color erasing power and weather resistance, and low impurity content.

Most of the titanium dioxide currently on the market is general-purpose titanium dioxide, which can be used in both solvent-based coatings and water-based coatings. However, after all, there are essential differences between water-based coatings and solvent-based coatings. These general-purpose titanium dioxides The dispersion effect of white powder in water-based paint is not very good. Therefore, in order to make titanium dioxide disperse well in water-based paint, the surface treatment method of titanium dioxide must be selected in a targeted manner.

(2) Powder coating

Different types of coatings with different uses have different requirements for titanium dioxide. For example, powder coatings require the use of rutile titanium dioxide with good dispersion. Anatase titanium dioxide has low achromatic power and strong photochemical activity. When used in powder coatings, the coating film is prone to yellowing. The rutile titanium dioxide produced by the sulfuric acid method has the advantages of moderate price, good dispersion, good covering power and achromatic power, and is very suitable for indoor powder coatings. However, titanium dioxide for outdoor powder coatings requires in addition to dispersion and covering power. In addition to good achromatic power, it is also required to have good weather resistance. Therefore, titanium dioxide for outdoor powder coatings is generally rutile titanium dioxide produced by the chloride method.

(3) Architectural coatings

Architectural coatings are required to be acid-resistant, alkali-resistant, water-resistant, and moisture-proof, and must have good adhesion on rough or smooth base surfaces. In addition to the good optical properties and pigment properties mentioned above, titanium dioxide used in architectural coatings is required to have high weather resistance and strong powder resistance, especially for exterior wall architectural coatings.