Dosage and Application of Titanium Dioxide in Coatings
Titanium dioxide has excellent optical, electrical properties and pigment application properties, so it has a wide range of use values. The physical, chemical and optical properties of titanium dioxide pigments are mainly determined by the original state of the pigment particles before coating and the chemical structure of the coating on the surface.
Titanium dioxide pigments generally use oxides of silicon, aluminum and zirconium as surface treatment agents, which are deposited on the surface of particles to form a coating, and the form, quantity and method of precipitation are controlled by process. Some also use organic treatment agents. Different surface treatment methods endow titanium dioxide with individual characteristics and different requirements for paint formulation design.
For the purpose of covering power, generally enamel 30-40 microns can cover it. The addition amount is 15-25% of the total formula; from the perspective of weather resistance and high gloss, in order to obtain a high weather resistance matte paint, it is necessary to use a matting powder for matting, and the principle of adding a small amount of titanium dioxide and no other fillers is considered; from a cost perspective Adding other system fillers reduces the cost. The addition of other system fillers will reduce the amount of titanium dioxide added, but the problem of brightness must be balanced; for interior wall latex paints that exceed the CPVC value, the amount of titanium dioxide added is 2%-4%.
Regarding the dispersion problem, wetting and dispersing additives may not be used in primers or topcoats with low requirements from the perspective of formulation cost, but the phenomenon of floating color and blooming should be controlled within an acceptable range. Adding controllable flocculation additives to the primer and topcoat can control the phenomenon of floating color and blooming.
In high-grade topcoats, low-molecular-weight wetting and dispersing additives can be used for titanium dioxide paste, and high-molecular-weight wetting and dispersing additives are used for other organic pigment pastes, which are generally compatible; Titanium dioxide with high dispersibility and high weather resistance, and the selection of appropriate wetting and dispersing additives, can solve the problem of floating color and blooming; if anti-corrosion primer, architectural latex paint and anti-corrosion topcoat, choose titanium dioxide with good dispersibility, With the help of wetting and dispersing additives, the dispersing effect can be achieved directly by using a high-efficiency disperser, eliminating the need for grinding.
The dosage and the variety of wetting and dispersing additives are different, so it is necessary to add the dosage according to the production requirements, in order to obtain a good effect of the topcoat.