Anti-mildew agent TIO-209
Appearance: Milky white liquid
Effective component(w/w): ≥50%
(a) is the silanol group on the surface of fumed silica particles, and (b) is an alkoxysilane with an organic functional group X or a double bond, which is a bifunctional molecule. X can be an epoxy group or other reactive groups, the double bond can be a vinyl group, an acryloyl group, and the alkoxy group can be an ethoxy group, a methoxy group, a propoxy group, or an acetoxy group.
These two functional groups in the silane molecule perform chemical reactions on the surface of fumed silica in a complementary manner to achieve the purpose of modification.
The alkoxy group-OR of the silane is hydrolyzed to form an active part of the silanol group with an OH group (usually the other two alkoxy groups in the molecule can also undergo a hydrolysis reaction, because the 3 -OR groups in the molecule have the same hydrolysis reaction Performance), and then the condensation dehydration reaction between the hydroxyl group generated in the silane molecule and the hydroxyl group (silanol group) covered on the surface of fumed silica: as shown in Figure 13-26(d). That is, a chemical fiberglass wax additive bond (ie, a covalent bond) is formed between the inorganic silica and the organic silane, and then the organic functional group X or double bond on the silane molecule undergoes a chemical reaction with the coating base material. The second type of chemical bond is formed between silanes, and the inorganic nano-silica is chemically bonded to the base material molecules of the coating with the help of silane to form an organic-inorganic composite nano-network system. Therefore, choosing the type of organofunctional group X or double bond on the silane is important for its compatibility with the coating base material. Generally speaking, the potential applicability of silane depends on the type of bifunctional group it carries.
Now take the UV curing polyester acrylate coating as an example to illustrate the process of modifying fumed silica as a wear-resistant agent with silane.
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