According to the commonly used electrical insulating materials according to their different chemical properties , can be divided into inorganic insulating material , organic insulating material and the insulating material mix .
Common inorganic insulating materials: mica , asbestos, marble , porcelain, glass , sulfur , etc., mainly used for motor winding insulation , appliances , switch backplane and insulators.
The organic insulating materials are: shellac , resins , rubber , cotton , paper, hemp, rayon, etc. , for the manufacture of most of the insulating paint coated winding wire insulation and the like.
Forming an insulating material by mixing various insulating materials made ??of these two materials are processed for use as electrical base shell.
A brief classification of rubber insulating material , silicone rubber insulation materials in electrical applications and progress in below. From a variety of silicone rubber after hydrolysis dichlorosilane , an element obtained by polycondensation of an organic elastomer. Silicone rubber has excellent high temperature resistance, weather resistance, ozone resistance, corona , good electrical insulation properties, surface hydrophobicity , low compression set characteristics , the unique properties of rubber varieties . It is ideal for use as an organic electrical insulating materials electrical industry in recent years has been more widely used in electrical insulation systems. Most domestic manufacturers are using composite insulators filled with more aluminum hydroxide (Al203 · 3H20) of methyl vinyl silicone rubber ( ie high temperature vulcanized silicone rubber ) as outdoor insulation materials, as well as used as a composite arresters , circuit breakers , transformers, high-voltage switches and wall casing jacket insulation materials. According to incomplete statistics, in 2001 our silicone rubber composite insulators on power lines running road reached 1.9 million , and the amount to more than 25% annual growth rate . Greatly promoted the development of the power industry , to improve the security of electricity , has a double benefit society and the economy. Since the beginning of the 1960s , many of the world 's developed countries, such as Germany, the United States, Britain , France, and Japan had already begun to study the use of organic polymers manufacturing outdoor composite insulators . The first insulating material used mainly alicyclic epoxy resins, ethylene propylene rubber , EPDM , PTFE , and RTV silicone rubber , etc., but these materials by the use of composite insulators run certain all the time after a number of problems , epoxy easy to aging , cracking, loss of hydrophobicity , surface tracking ; hydrophobicity decline , fading, cracks EPDM run a few years later, to generate tracking ; polytetramethylene no migration of fluoride hydrophobic properties prone to corrosion and other issues after the umbrella ripped through the surface dirt , and expensive, processing difficulties ; RTV silicone rubber electrical resistance to tracking and erosion resistance and mechanical strength is not good enough , there appears surface mechanical damage and corrosion cracking and other issues.