Basic introduction of silicone materials

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

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

 

Classification of silica gel: According to its vulcanization characteristics, silica gel can be divided into two types: hot vulcanized silicone rubber and room temperature vulcanized silicone rubber. According to the different performance and use, it can be divided into general type, ultra low temperature resistant type, ultra high temperature resistant 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 and so on.

 

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

 

1. During the mixing process, due to the low intermolecular cohesion of raw silicone rubber, high-reinforcement and high-temperature-resistant white carbon black filler has become the most important compounding agent for silicone rubber. When selecting other compounding agents, nursery rhymes need to consider high-temperature resistance. Under the application conditions of silicone rubber, they must not volatilize, decompose, carbonize or change color, 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 must be prevented when mixing When foreign acids and alkalis are brought in, the acidic substances generated by the decomposition of peroxide vulcanizing agents must be removed in time! 2. Put the mixed raw rubber and other ingredients into the vacuum kneader for cooking. The temperature is not high at the beginning. During the stirring process, the temperature is slowly increased by friction and reaches 155-160 degrees. It will be done in half an hour. 3. Put the boiled glue in an open mill to grind it into a roll. Just be careful not to get dirty. The number of rolls only needs to be 2-3 revolutions. 4. After it is smoothed, it needs to be cooled and the time is about After 3-4 hours, filter the glue through the screen, the purpose is to filter out some solid materials in the glue.

 

What are the types and characteristics of white carbon black? There are two main methods: gas phase method and precipitation method: gas phase method: mostly starting from silicon tetrachloride, and after mixing with chlorine and oxygen (air), at a high temperature above 1000 degrees, hydrogen is first burned with oxygen to produce water, and then with both After the action of silicon tetrachloride, it is hydrolyzed to produce fine powder. After coalescence, capture and acid removal, a white carbon black product is obtained. Advantages of the gas phase method: pure height, less sioh, high reinforcement rate, hot air vulcanization, high vulcanizate transparency, good electrical properties, airtightness, cushion resistance and dynamic fatigue resistance. Gas phase method uses: car parts, wires, cables, medical food, high-strength, high-transparency silicone rubber products, cushion-resistant gaskets. Precipitation method: starting from water glass, adding hydrochloric acid or sulfuric acid under stirring to neutralize the reaction to obtain SIO2 precipitate, 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 the precipitation method: vulcanized rubber has good resilience, compression set, good swelling resistance and processing performance, low price, and the rubber is not easy to structure, and can only be used for filling and reinforcing rubber and plastic products. Application of precipitation method: general molded products, rubber rollers, oil-resistant gasket materials.

 

What is the difference between silicone and rubber? We usually mistakenly think that silicone is a kind 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 is more environmentally friendly.