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Silica factory heat treatment modification refers to the nano-SiO2 in a certain medium heating, insulation, cooling, nano-SiO2 by changing the surface or internal structure to control its performance of a comprehensive process. After the heat treatment, the moisture content of the SiO2 surface is low, and the moisture absorption capacity of the filled product is also decreased. The reason may be due to the dehydration of the adjacent hydroxyl groups with hydrogen bonding under high temperature heating condition to form stable bonding, which leads to the decrease of water absorption. This method is simple and economical, but only through the heat treatment, can not improve the bonding effect of the interface at the time of filling, so in practical applications, often using nano-SiO2 zinc compound treatment at 200-400 ℃ under the conditions of heat treatment, Or by using a silane coupling agent and a transition metal ion to treat the nano-SiO2 after heat treatment, or with polydimethyl disiloxane to modify SiO2, and then heat treatment.

Surface chemical modification refers to the surface modification agent and some of the surface of the particle chemical reaction to achieve the purpose of modification. Due to the presence of unsaturated residues on the surface of nano-SiO2 and different hydroxyl groups, these reactive groups can react with some surface modifiers, so that SiO2 surface with a specific chemical activity of organic groups, improve the SiO2 particles and various Organic solvents and polymer matrix compatibility between. According to the different chemical reactions, surface chemical modification method can be divided into coupling agent modification, alcohol ester surface modification and polymer grafting modification.

Through a certain process to make some modifiers and fumed silica on the surface of the silicon hydroxyl reaction, to eliminate or reduce the number of silicon hydroxyl, so that the fumed silica from the hydrophilic into hydrophobic, can improve the two compatibility of silicon oxide with polymer. At present, the improvers used in the silica factory are alcohols, fatty acids, silane coupling agents and so on.