Silica, also known as hydrated silica, activated silica and precipitated silica, is a highly dispersed amorphous powder or flocculent powder with light weight, high electrical insulation, porosity and water absorption .

Its primary particle size is less than 3 μm, so it has a large surface area, has good reinforcement and thickening effects, and good dispersion, suspension and vibration liquefaction characteristics. It has been widely used in plastics, rubber, papermaking, coatings, dyes and inks. In several fields, especially in the rubber industry, silica ranks first for its superior reinforcement and transparency. However, due to the existence of active silicon hydroxyl groups, adsorbed water and acid regions on the surface of silica due to the preparation process, the silica is hydrophilic and difficult to infiltrate and disperse in the organic phase. In the rubber vulcanization system It is not well compatible with polymers, which reduces the vulcanization efficiency and reinforcement performance, making it unusable in some special fields. The modified white carbon black improves the surface activity and the dispersion and compatibility in the organic phase, thus greatly broadening the application field of the product and increasing the high added value of the white carbon black.

Silica can be divided into physical method and chemical method according to its processing method. The silica products prepared by physical methods are not of high grade, while the silica fillers required by the rubber industry are usually produced by chemical methods. Chemical method can be divided into dry pyrolysis method (including gas phase method and arc method) and wet method, wet method can be divided into precipitation method according to its formation characteristics (including sulfuric acid precipitation method, hydrochloric acid precipitation method, nitric acid precipitation method, carbon dioxide precipitation method) method and hydrothermal method) and gel method (including ordinary dry type and airgel type). At present, there are two main production processes of white carbon black at home and abroad. One is the gas phase method using silicon tetrachloride as the raw material. The silicon tetrachloride gas is placed in the flow of hydrogen and oxygen, and hydrolyzed under high temperature conditions. Obtain smoky silica, then condense it into floc, then separate and deacidify to obtain the product. Silica produced by the gas phase method is a high-quality product with high purity and small particle size, and is generally used as a fine filler. However, it is limited due to its high raw material price, long reaction process, high energy consumption in the production process, and high product price. The other is the acid precipitation method using water glass as raw material, that is, the Si2 powder that is loose, finely dispersed, and precipitated in a flocculent structure is obtained from water glass through acidification. White carbon black is prepared by acid precipitation method, the production process is simple, the product cost is low, but the product particle size is large, the activity is low, and the product quality is low.

In addition to using silica as the main filler in car tire tread rubber, using silica in carcass rubber can further reduce heat generation and rolling resistance. By using special high-dispersion silica, combined with high-structure fine particle carbon black, the use of silica can be expanded, and they can be used in truck tires. Using this optimal filling system can meet the main performance requirements of truck tires, that is, reduce the hysteresis loss of the tire, thereby reducing the rolling resistance, and at the same time, maintain the wear resistance.