Basic introduction of silicone material
Issuing time:2020-03-22 14:55
Silica gel is a highly active adsorption material, which is an amorphous substance. It contains polysiloxane, silicone oil, silica (silica), coupling agents, fillers, etc. The main component is silica. The molecular formula is mSiO2 · nH2O. It is insoluble in water and any solvents, non-toxic and tasteless, and stable in chemical properties. It does not react with any substance except strong alkali and hydrofluoric acid. Various types of silica gel have 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.
Silicone raw materials
Classification of silica gel: According to its vulcanization characteristics, silica gel can be divided into two types: heat-cured 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 resistance type, ultra high temperature resistance type, high strength type, oil resistance 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 and so on.
What are the molding conditions from raw rubber to compound rubber?
1. During the mixing process, due to the low cohesive force of the 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 Requirements, that is, under the conditions of silicone rubber application, they must not volatilize, decompose, carbonize, or discolor. In order to maintain the heat resistance of the silicone rubber and reduce the breakage of silicon bonds by acid and alkali attack, it is necessary to prevent it when mixing. Foreign acids and alkalis are brought in, and the acidic substances produced by the decomposition of peroxide curing agents must be removed in time! 2. Put the mixed raw rubber and other ingredients into a vacuum kneader and cook it. The temperature is not high at first. During the stirring process, the temperature slowly rises through friction to reach 155-160 degrees. Just half an hour will be fine. 3, put the cooked glue in the open mill to smooth it and roll it, as long as it is careful not to get dirty, the number of times of rolling is only 2-3 times. 4, after smoothing, it needs to cool, the time is about In 3-4 hours, then filter the gel through a sieve to filter out some solid materials in the gel.
Silicone raw materials
What are the types and characteristics of white carbon black? There are mainly two types of gas phase method and precipitation method: gas phase method: most of the system is based on silicon tetrachloride. After mixing with chlorine gas and oxygen (air), at high temperature above 1000 degrees, hydrogen first burns with oxygen to generate water, and then both After the action of silicon tetrachloride, hydrolysis and formation, fine powder, after agglomeration, trapping and acid removal, white carbon black products are obtained. Gas phase method advantages: pure height, less sioh, high reinforcement rate, hot air vulcanization, high vulcanizate transparency, good electrical properties, tightness, cushion resistance and dynamic fatigue resistance. Vapor phase application: car parts, wires, cables, medical food, high strength, high transparent silicone rubber products, cushion gaskets. Precipitation method: Start with water glass, add hydrochloric acid or sulfuric acid under stirring to neutralize the reaction, obtain SIO2 precipitate, filter, dry, and grind to high-fine white carbon black. It can also be obtained from an alkaline earth metal silicic acid by an acid decomposition reaction. Advantages of precipitation method: vulcanizate resilience, compression compression set, good swelling resistance and processing performance, cheap price, rubber material is not easy to structure, and can only be used for rubber, plastic products filling and reinforcement. Use of precipitation method: general molded products, rubber rollers, oil-resistant gasket materials.
What is the difference between silicone and rubber? We often mistakenly think that silicone is a kind of rubber, but this is actually wrong. The main ingredients of the raw materials of silica gel are extracted from silica (such as silicone oil, white carbon black), and the raw materials of rubber are extracted from resin. The cost of silicone is more expensive and more environmentally friendly than rubber.