Fumed silica has the characteristics of small particle size, high surface activity and high purity. It is widely used in the field of coatings and can play a thixotropic and anti-settling function. The specific mechanism of action is as follows:
(1) There are a large number of silanol bonds on the surface of fumed silica, which can form hydrogen bonds with itself or with the substrate to form a "net"-like structure, "supporting" the pigment or other filler to prevent it from sinking or agglomerating;
(2) Fumed silica has a thickening effect. Choosing a suitable type of fumed silica can increase the viscosity of the coating to a certain extent. Then the resistance encountered by the pigment or filler during the falling process will naturally increase, which can effectively prevent sinking or agglomeration;
(3) Fumed silica has high surface activity. The surface charge of fumed silica can be adjusted through modification treatment. Because in some specific coating applications, the pigment or filler also has a certain activity and can agglomerate itself or combine with each other. At this time, fumed silica can play a role in neutralizing the charge, preventing the agglomeration or agglomeration between the pigment and filler, and further improving the storage of the pigment.
(4) In powder coatings, fumed silica can be used as an external additive. Fumed silica particles are adsorbed on the surface of powder coatings, separating the coating particles and promoting fluidity. Some fumed silica can also act as a moisture-proof agent to prevent the coating from agglomerating.
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