Matting Additive
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Silica Matting Agent
in the broad field of obtainable silicas for matting there are two groups which differ in terms of their production process. One is the hydro-thermal process, which produces silicas with a relatively soft morphology. By using the silica-gel process products can be obtained which have a harder morphology. Both processes are capable of producing standard silica and after treated products. After treatment means that the silica surface can be partially modified with organic (waxes) or inorganic materials. Compared to silica-gel matting agents, modified silica possess a different particle size, particle size distribution, in the pore volume. Hydrothermal matting agents are different in particle size and distribution. We can also find untreated and treated materials. Currently there is only one product popular for specific application, which is produced according to pyrogenic process, and shows a very high matting efficiency, especially in water-based systems.
Wax Matting Agent
Today, there is a diverse range of waxes in the market. The most used waxes for coatings and inks are based on Polyethylene, Polypropylene, Carnauba, Amid. Waxes products based on Polytetrafluorethylene PTFE are also used as matting agents.In contrast to silicas, waxes modify the surface properties of a paint film by floating to the top of the surface. This phenomenon affects the following properties:
Fillers as Matting Agents
Although the appearance of paints change through the addition of previously mentioned matting additives, the performance is not affected. By using specific fillers we clearly increase the Pigment-Volume-Concentration of paint involving with all the side effects it implies. That's the reason why this method of matting is limited for only pigmented, economical lower classes paint systems.
The fillers with preferential narrow particle size distribution have to disperse together with the pigments. To adjust a required gloss degree it is praxis to adjust it by using stir in Silica at the end of the paint production process.
