Silica gel is a kind of highly active adsorption material, which is an amorphous material, containing polysiloxane, silicone oil, silica (silica), coupling agent and filler, etc. its main component is silica, and its chemical formula is msio2 · nH2O. Insoluble in water and any solvent, non-toxic and tasteless, stable in chemical properties, no reaction with any substance except strong base and hydrofluoric acid. Different types of silica gel have different microporous structures due to different manufacturing methods. The chemical composition and physical structure of silica gel determine that it has many characteristics that can not be replaced by other similar materials: high adsorption performance, good thermal stability, chemical stability, high mechanical strength, etc.








Silica gel raw materials


Classification of silica gel: according to its vulcanization characteristics, silica gel can be divided into hot vulcanized silicone rubber and room temperature vulcanized silicone rubber. It can be divided into general type, super low temperature resistant type, super high temperature resistant type, high strength type, oil resistant type, medical type and so on. According to the different monomers, it can be divided into methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorosilicone, nitrile silicone rubber, etc.






What are the forming conditions from raw rubber to mixed rubber?






1. In the mixing process, due to the low intermolecular cohesion of raw silicone rubber, the high reinforcing and high-temperature resistant silica filler becomes the most important compounding agent of silicone rubber. When selecting other compounding agents, the nursery rhyme needs to consider the requirements of high-temperature resistance, that is, under the application conditions of silicone rubber, they shall not volatilize, decompose, carbonize or discolor, etc., in order to maintain the heat resistance of raw silicone rubber and reduce Silicon bond is broken by acid and alkali attack. When mixing, it is necessary to prevent foreign acid and alkali from entering. It is also necessary to remove the acid produced by decomposition of peroxide sulfurizer in time! 2. Put the mixed raw rubber and other ingredients into the vacuum kneader and boil them. At the beginning, the temperature is not high. In the process of mixing, the temperature height is slowly reached 155-160 degrees by friction, and it will be half an hour later. 3. When the boiled rubber is put into the open mill to be ground and rolled, as long as it is not dirty, the rolling times only need 2-3 turns. 4. After grinding, it needs to be cooled for about 3-4 hours, and then filter the rubber through the screen, so as to filter out some solid materials in the rubber.








Silica gel raw materials


What are the types and characteristics of silica? There are mainly two kinds of gas-phase method and precipitation method: gas-phase method: most of them start from silicon tetrachloride, mix with chlorine gas and oxygen (air), at a high temperature of more than 1000 degrees, hydrogen first burns with oxygen to generate water, and then all react with silicon tetrachloride, hydrolyze to generate, micropowder, after coalescence, capture and deacidification, white carbon black products are obtained. Advantages of gas phase method: pure height, less SiOH, high reinforcement rate, hot air vulcanization, high transparency of vulcanizate, good electrical performance, sealing, pad resistance and dynamic fatigue resistance. Application of gas phase method: car parts, wires, cables, medical food, high strength, high transparent silicone rubber products, gasket resistant gasket. Precipitation method: starting from water glass, adding hydrochloric acid or sulfuric acid to neutralize the reaction under agitation to obtain SiO2 precipitation, filtering, drying and grinding to high fineness silica. It can also be obtained from alkaline earth metal silicic acid through acid decomposition reaction. Advantages of precipitation method: the vulcanizate has good resilience, compression permanent deformation, swelling resistance and processing performance, low price, and the rubber material is not easy to structure, and can only be used for filling and reinforcement of rubber and plastic products. Application of precipitation method: general molding products, cots, oil resistant gasket materials.






What's the difference between silica gel and rubber? We usually think of silica gel as a kind of rubber. In fact, it's wrong. The main components of silica gel raw materials are extracted from silica (such as silicone oil, white carbon black), while the raw materials of rubber are extracted from resin. The cost of silica gel is more expensive than rubber and more environmentally friendly.