Among the pigments, white pigment is widely used, and it is used in both white and light-colored paints, so the amount of white pigment in paint production is much more than other pigments. The white pigments commonly used in paints are zinc white, zinc barium white, titanium white and so on. As some synthetic resin coatings polymerization degree is large, if you add zinc white, it has the tendency to thicken because zinc white has alkaline, and the free lipid in the coating anti-acid effect; if you add zinc barium white, the weather resistance is poor. But the use of titanium white can improve the above shortcomings. Because titanium white particles are small and uniform, high photochemical stability, in terms of coverage, rutile titanium white is 7 times that of zinc white, is 5.56 times that of zinc barium white, anatase titanium white is 5.57 times that of zinc white, is 4.3 times that of zinc barium white; in terms of achromatic power, rutile titanium white is 8.3 times that of zinc white, is 6.25 times that of zinc barium white, anatase titanium white is 6.4 times that of zinc white, is 4.8 times that of zinc barium white. 4.8 times more than zinc white. In terms of application effect, 1t of titanium white is equivalent to at least 4t of zinc barium white; in terms of service life (meaning outdoor chalk resistance), the coating with titanium white as pigment is 3 times higher than the coating with zinc barium white as pigment. Therefore, the use of titanium white can greatly reduce the amount of pigments in the entire paint, while the paint made of bright colors, not easy to yellow, light, heat, wear, weathering, alkali, sulfur, diluted acid resistance. It is because of the superior performance of titanium white than zinc white, zinc barium white, so it has become an essential * good white pigment in the production of coatings. The amount of titanium dioxide accounts for more than 90% of the total pigments used in coatings, and more than 95% of the white pigments used in coatings. It accounts for 10% to 25% of the cost of raw materials for coatings.
Titanium dioxide is extremely versatile in the coating industry and its role cannot be ignored. Cr-95 and cr-80, produced by Ishihara, have a place in the coatings industry, with high gloss, high weathering and anti-powdering properties and high dispersibility, especially for industrial and outdoor coatings. But Ishihara was not satisfied with the status quo, so our PFC-105 was developed. This is a rutile titanium dioxide produced by the chlorination process, with a coating of zirconium oxide, alumina and silicon oxide, and with Ishihara’s* surface treatment technology, this model has better film properties and better weathering resistance than other conventional grades. This allows you to improve the quality of the product while reducing the amount added and reducing costs. When comparing with our cr-95 for irradiation test. It can keep the gloss more rich and longer. In adding silicone emulsions with PFC-105 even better than fluorocarbon emulsions with the better cr-95. Therefore this titanium dioxide can greatly increase the weather resistance of exterior wall coatings.
Effect of titanium dioxide on the covering power of paint
One of the important roles of titanium dioxide in coatings* is to use its opaque function of dispersing in the medium to achieve the covering effect. The covering power of titanium dioxide will vary according to its scattering power, particle size and particle size distribution.
1. The effect of the purity of titanium dioxide on the covering power of coatings
The refractive index of titanium dioxide is * among white pigments, and the reflection and absorption of light can cause covering and decolorization. By improving the scattering ability of titanium dioxide and reducing its light absorption ability, it can affect the transparency, covering power and achromatic power of coatings.
The main means to improve the scattering ability of titanium dioxide is to make the particle size and particle size distribution of titanium dioxide meet the requirements of the species as well as have good dispersion. Reduce the absorption capacity mainly by the processing process as far as possible to remove impurities that can produce color, improve the purity of titanium dioxide to reduce light absorption energy.
2. the effect of titanium dioxide particle size on the covering power of coatings
Titanium dioxide particles of different shapes and sizes, the degree of light scattering is very different, is a key factor affecting the coverage of titanium dioxide. Research shows that, under the same conditions, when the titanium dioxide particle size of 160 ~ 350nm, that is, the particle size is about 0.4 ~ 0.5 times the wavelength of visible light, it has a strong scattering ability of light, in the application will directly affect the covering power of the coating.
In the coating system, if the film-forming material is not enough to completely cover the titanium dioxide particles, it will make the titanium dioxide particles in contact with each other, agglomeration, to some extent equivalent to the increase in titanium dioxide particle size, and make the coating coverage decreased.
3. the effect of titanium dioxide dispersion on the covering power of coatings
In the field of coatings, the degree of dispersion of powder particles largely determines the performance of the product. When the coating is produced, the dispersion of titanium dioxide has to go through the process of wetting, sanding and dispersion.
However, as titanium dioxide has certain activity, the environment of the system used will have certain influence on its dispersion, and it is easy to appear flocculation, precipitation, suspension and other bad dispersion, so the degree of dispersion also affects the covering power of the coating.
4. the amount of dispersant on the effect of coating coverage
Titanium dioxide in the dispersion, due to its small particles relative to the filler, tends to particle cohesion, so the choice and amount of dispersant will affect the dispersion of titanium dioxide, while affecting the covering power of the paint film. Some experiments show that the degree of dispersion of the filler increases with the increase of the amount of dispersant, and the increase of dispersion makes the distribution range of the particle size of the filler narrow, the particle size becomes smaller, thus increasing the covering power of the paint film.