1、 Introduction to White Carbon Black

The chemical formula of white carbon black is SiO2nH2O, and it is named white carbon black because its use is similar to carbon black and it is white. White carbon black can be divided into precipitated white carbon black (precipitated hydrated silica) and gas-phase white carbon black (gas-phase silica) according to different production methods. The two products have different production methods, properties, and uses.

Gas phase production mainly uses silicon tetrachloride and silica obtained from air combustion, with fine particles and a median particle size of less than 5 microns.


The precipitation method of production involves adding sulfuric acid to sodium silicate to precipitate silica. The median particle size is approximately 7-12 microns. Gas phase white carbon black is expensive and not easily hygroscopic, and is commonly used as a matting agent in coatings. Precipitation method white carbon black is inexpensive and easy to absorb moisture. Mainly used as a filler and reinforcing agent in rubber and plastic products.

The products introduced below are produced using sulfuric acid precipitation method, namely precipitation method white carbon black. The white carbon black mentioned below is all precipitation method white carbon black.

2、 The production principle of precipitated white carbon black

The reaction between water glass and sulfuric acid generates hydrated silicate Na2O · mSiO2+H2SO4+nH2o - → Na2SO4+mSiO2 · (n+1) H2O ↓

(The reaction process requires heating). The reaction solution is dehydrated by pressure filtration, washed, and beaten to obtain white carbon black slurry, which is dried by spray to obtain finished white carbon black.

4、 The significance of various indicators of white carbon black in application










1. The magnitude of the reinforcing effect of silica on specific surface area mainly depends on its specific surface area. Generally, as the specific surface area increases, all strength indicators of rubber products increase, but the resilience decreases, the tear strength decreases, and it is not wear-resistant. It is difficult to disperse during mixing, has high heat generation, and the Mooney viscosity of the rubber material is high, making it easy to burn. Therefore, different formulations and uses require different specific surface areas, The influence of specific surface area on the physical and mechanical properties of vulcanized rubber is not consistent.












2. The oil absorption value reflects the degree of structure. When the oil absorption value is large, the degree of structure is small. The tensile strength, tensile strength, and hardness of vulcanized rubber are generally large, especially the wear resistance is small, but the elongation is low.










3. The reduction in burning at 900 ℃ reflects the surface hydroxyl groups. When there are too many hydroxyl groups on the surface, it is easy to cause the structure of rubber composite materials, making the material brittle. Affects processing performance, and the vulcanized rubber is prone to block shedding, and the surface hydroxyl groups have a strong adsorption effect on the vulcanization promoter, prolonging the vulcanization time.










4. The reduction in heating at 105 ℃ reflects the amount of free water in the particle voids. When there is too little, it becomes difficult to refine the rubber material with high structural degree. If the heating reduction is zero, white carbon black is useless, and it is generally more appropriate to control it at around 6%.










5. The pH value is generally around 7, and as the pH value increases (acidity decreases), the vulcanization rate of the rubber material accelerates.










6. The lower the soluble salt content, the better, but if you want to significantly reduce the soluble salt content, it will significantly increase the production cost.










Looking at the world situation, the number of new varieties of silicon compounds has not increased significantly in recent years, while the development of inorganic silicon compound applications is given more attention. From the current trend, a large amount of white carbon black will enter many fields such as light industry, food, medicine, construction, electronics, metallurgy, and mechanical industry, with great development prospects.