Application of silica matting agent in coatings?
Pigments or fillers are added to the paint and evenly distributed in the film to create a slightly rough surface. The larger the particles on the surface, the lower the gloss.

Sometimes precipitated calcium carbonate or talc is used in the production of matt coatings, and the amount is large, which often exceeds the physical properties, resulting in delamination and hard precipitation. The use of matting agents can avoid the critical pigment volume concentration of this paint film. Produces a matte coating phenomenon.

Commonly used organic matting agents and inorganic matting agents, inorganic matting agents are mainly silica matting agents, whose chemical composition is silicon dioxide, and the surface is divided into organically treated and untreated.

1. Pyrolytic silica matting agent: Quartz sand (powder) processed by grinding, with a lot of impurities, the main component is silicon dioxide, can not be called white carbon black, and has no matting performance. It is only used as a filler for coatings, and has no matting effect. , and as a matting agent, the silica coating is mainly synthetic silica, divided into calcined silica and precipitated silica, and the microstructure is amorphous or glassy.

Precipitated silica is based on quartz sand as the main raw material, sodium carbonate or sodium hydroxide and its temperature react in the furnace, and then pass through the melting processing system. Fumed silica is made by hydrolyzing silicon tetrachloride in an oxyhydrogen flame. Compared with natural silica, silica has high silica purity, high inertness and UV resistance.

1. Itis the refractive index of amorphous silica, which is similar to the refractive index of many resins in the coating industry, so amorphous silica with good optical properties can be used as a matting agent in coatings.

2. The extinction mechanism of carbon black and pyrolytic silica matting agent: the varnish coated mirror film without matting agent is in a leveling state, when the light reaches the surface of the film mirror, the incident light is partially absorbed and partially reflected part of the film is glossy. The film contains a silica matting agent that evenly distributes the silica particles in the film to form a slightly rough surface. Scanning electron micrographs that can be seen from the cross-section of the film's matting agent particles are uniformly distributed in the film and are clearly seen when incident light reaches the film's uneven surface, diffuse reflection, which is scattered to produce low gloss and no Light matte appearance.

High porosity, good particle size distribution and suitable surface treatment silica matting agent can get good matting effect.