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Silicone
Aug 17, 2018

Silicone is a highly crosslinked network of polyorganosiloxanes, usually methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane or methyl Various mixtures of phenyldichlorosilane are hydrolyzed at a lower temperature in the presence of an organic solvent such as toluene to obtain an acidic hydrolyzate. The initial product of hydrolysis is a mixture of cyclic, linear and crosslinked polymers, usually also containing a substantial amount of hydroxyl groups. The hydrolyzate is washed with water to remove the acid, and the neutral condensate is thermally oxidized in the air or further polycondensed in the presence of a catalyst to form a highly crosslinked stereo network structure.


Silicone is a thermoset plastic and one of its most outstanding properties is its excellent thermal oxidative stability. After heating at 250 ° C for 24 hours, the silicone weight loss is only 2 to 8%. Another outstanding property of silicone is its excellent electrical insulation properties, which maintain its good insulation properties over a wide temperature and frequency range.


In view of the above characteristics, silicone resin is mainly used as insulating varnish (including varnish, enamel, paint, dipping varnish, etc.) to impregnate H-class motor and transformer coil, and is used to impregnate glass cloth, glass cloth and asbestos cloth to make motor sleeve. Pipes, electrical insulation windings, etc. Bonding mica with silicone insulating varnish can produce a large area of mica sheet insulation material, which is used as the main insulation of high voltage motors. In addition, silicone can also be used as heat-resistant, weather-resistant anti-corrosion coatings, metal protective coatings, waterproof and moisture-proof coatings for construction projects, release agents, adhesives and secondary processing into silicone plastics for the electronics, electrical and defense industries. In the past, it is used as an insulating material for semiconductor packaging materials and electronic and electrical components.


Silicone resins can be roughly classified into silicone insulating varnishes, silicone coatings, silicone plastics and silicone adhesives according to their main uses and cross-linking methods.