Silica gel is a highly active adsorption material, which is an amorphous substance. It contains polysiloxane, silicone oil, white carbon black (silicon dioxide), coupling agent and filler, etc. The main component is silicon dioxide. The molecular formula is mSiO2·nH2O. It is insoluble in water and any solvent, non-toxic and tasteless, chemically stable, and does not react with any substances except strong alkali and hydrofluoric acid. Various types of silica gel form different microporous structures due to different manufacturing methods. The chemical composition and physical structure of silica gel determine that it has many characteristics that are difficult to replace by other similar materials: high adsorption performance, good thermal stability, stable chemical properties, and high mechanical strength.

Classification of silica gel: silica gel can be divided into two categories according to its vulcanization characteristics: thermal vulcanization silicone rubber and room temperature vulcanization silicone rubber. According to different properties and uses, it can be divided into general-purpose type, ultra-low temperature resistance type, ultra-high temperature resistance type, high-strength type, oil-resistant type, medical type and so on. According to the different monomers used, it can be divided into methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, fluorosilicone, nitrile silicone rubber, etc.

What are the conditions for each molding from raw rubber to compound rubber?

1. During the mixing process, due to the low intermolecular cohesion of the raw silicone rubber, the silica filler with high reinforcement and high temperature resistance becomes the most important compounding agent for silicone rubber. When selecting other compounding agents, nursery rhymes need to consider high temperature resistance. requirements, that is, under the application conditions of silicone rubber, they must not be volatilized, decomposed, carbonized or discolored, etc. In order to maintain the heat resistance of the raw silicone rubber and reduce the breakage of the silicon bond by acid and alkali attack, it is necessary to prevent the compounding. Foreign acids and alkalis are brought in, and the acidic substances produced by the decomposition of peroxide vulcanizing agents must be removed in time! 2. Put the kneaded raw rubber and other ingredients into the vacuum kneader to cook, the temperature is not high at the beginning, in the process of stirring, slowly increase the temperature through friction, and when it reaches 155-160 degrees, then Just over half an hour. 3. Put the boiled glue into the open mill to smooth it and roll it into rolls. Just be careful not to get dirty, and the number of rollings only needs 2-3 circles. 4. After grinding, it needs to be cooled down. In 3-4 hours, then filter the glue through a mesh, the purpose is to filter out some solid materials in the glue.

What are the types and characteristics of silica? There are mainly two kinds of gas phase method and precipitation method: gas phase method: mostly starting from silicon tetrachloride, after mixing with chlorine gas and oxygen (air), at a high temperature of 1000 degrees or more, hydrogen is first burned with oxygen to generate water, and then both are mixed with oxygen. Silicon tetrachloride acts, hydrolyzed to form, micropowder, after coalescence, trapping and acid removal, white carbon black product is obtained. Advantages of gas phase method: pure height, less sioh, high reinforcement rate, hot air vulcanization, high transparency of vulcanizate, good electrical performance, excellent sealing, cushion resistance and dynamic fatigue resistance. Gas phase method uses: car parts, wires, cables, medical food, high-strength, high-transparency silicone rubber products, gasket-resistant gaskets. Precipitation method: mostly starting from water glass, adding hydrochloric acid or sulfuric acid to neutralize the reaction under stirring to obtain SIO2 precipitation, which is filtered, dried, and ground into high-fineness white carbon black. It can also be obtained from alkaline earth metal silicic acid through acid decomposition reaction. Advantages of precipitation method: vulcanized rubber has good resilience, compression set, good swelling resistance and processing performance, low price, and the rubber compound is not easy to be structured, and can only be used for filling and reinforcement of rubber and plastic products. Application of precipitation method: general molding products, rubber rollers, oil-resistant gasket materials.

What is the difference between silicone and rubber? We often mistake silicone for a type of rubber, but this is wrong. The main components of the raw materials of silica gel 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 it is more environmentally friendly.