Can silica fume really replace titanium dioxide in latex paint?

Can silica fume really replace titanium dioxide in latex paint?

Wollastonite powder is used in latex paint, which saves a lot of titanium dioxide and reduces costs without compromising the performance of the latex paint. The advantage of the present invention lies in the direct use of untreated wollastonite powder in latex paint by selecting dispersants, thereby avoiding pre-treatment of wollastonite powder and greatly reducing coating costs. Replacing 30% titanium dioxide with 320 mesh wollastonite powder can reduce the cost of latex paint within the range of 130 to 200 yuan (RMB)/ton.

After being crushed to a certain particle size, silica fume can replace some titanium dioxide in coatings. Its main disadvantage is that the coating is unstable and prone to precipitation.

The present invention involves crushing natural wollastonite and directly using it without chemical pretreatment to replace 10-40% titanium dioxide in latex paint. By adding a mixture of dispersants such as polyacrylate and sodium hexametaphosphate, the stability of this type of latex paint is ensured and the cost is reduced. The weather resistance of latex paint has been improved, while other properties remain unchanged.

In the application of exterior wall latex paint, silica fume has a high hardness, a Mohs hardness of 4.5-5, a low coefficient of thermal expansion, and is an inert filler with good weather resistance. Its needle like structure has crack resistance, high whiteness, and good coloring power. When color is adjusted, the color brightness is high. As an important filler, it is increasingly used in exterior wall coatings.

The application of wollastonite in interior wall latex paint used to be limited due to its yellowish hue. However, with the advancement of deep processing technology in wollastonite production enterprises, the whiteness can reach over 90. For example, the highest whiteness of wollastonite JLH6W from Shenzhen Jinhaohui Chemical can reach 92. It can be fully used in interior wall coatings.

The needle like structure of wollastonite can increase the porosity of high PVC interior latex paint, thereby improving its covering power. The needle like structure of wollastonite can help improve its scrub resistance. Data shows that adding 5-8% wollastonite to interior latex paint can improve its scrub resistance by 100 times. In addition, the needle like structure of silica fume can reduce corner light, improve compressive light resistance, and improve construction performance.