(2) room temperature vulcanized silicone rubber (RTV) (1) hot vulcanized silicone rubber (HTV)
Hot Vulcanized Silicone Rubber (HTV) is the most important class of silicone products, methyl vinyl silicone rubber (VMQ) is the most important varieties of HTV, commonly known as high temperature rubber.
Methyl vinyl silicone rubber (raw rubber) is colorless, odorless, non-toxic, no mechanical impurities of the gel, raw rubber according to the need to add the appropriate reinforcing agent, structural control agents, vulcanizing agents and other additives together with the mixing, and then temperature molding or extrusion molding, and then by the two-stage vulcanization into a variety of products. The products have excellent electric insulation, strong resistance to arc, corona, electric spark, waterproof, moistureproof, impact resistance, shock resistance, physiological inertia, breathability and other properties.
Mainly used in aviation, instrumentation, electronics and electrical appliances, navigation, metallurgy, machinery, automotive, medical and health care sectors, can be made in various shapes of seals, gaskets, tubes, cables, but also to do the human body organs, blood vessels, breathable membrane, and rubber mold, precision casting of the mold release agent, and so on.
Room temperature vulcanized silicone rubber generally includes condensation type and add molding two categories.
Room temperature vulcanized silicone rubber is a vinyl linear polysiloxane as the base rubber, with hydrogen-containing silicone as the cross-linking agent, in the presence of catalysts at room temperature to medium temperature cross-linking reaction occurs and become elastomer. It has good heat resistance, hydrophobicity, electrical insulation, and at the same time, due to the introduction of active end groups, it has excellent physical and mechanical properties, especially in the tensile strength, relative elongation and tear strength has been significantly improved. It is suitable for a variety of vulcanization methods, such as radiation vulcanization, peroxide vulcanization and addition molding vulcanization, and is widely used in heat-resistant, moisture-resistant, electrically insulating, high-strength silicone rubber products.
Two-component room temperature vulcanized silicone rubber (referred to as RTV-2 rubber) is not as convenient as RTV-1 rubber, but the proportion of its components is rich in variation, a variety of specifications can be obtained from a variety of vulcanized products, but also the depth of vulcanization, and is widely used in electronics and electrical appliances, automobiles, machinery, construction, textiles, chemical industry, light industry, printing and other industries for the insulation, encapsulation, embedded seams, seals, It is widely used in electronics and electrical appliances, automobiles, machinery, construction, textiles, chemical industry, light industry, printing and other industries as insulation, encapsulation, embedded seams, sealing, moisture-proof, shock-resistant, and roller materials. In addition, because RTV-2 has excellent mold releasing properties, it is used as a soft molding material for a large number of cultural relics, handicrafts, toys, electronic and electrical appliances, mechanical parts and other reproduction and manufacturing.
Condensation type room temperature vulcanized silicone rubber is characterized by the condensation reaction between silicone hydroxyl group and other active substances, and can be crosslinked at room temperature to become elastomer silicone rubber, the product is divided into one-component packaging and two-component packaging in two forms. One-component room temperature vulcanized silicone rubber (referred to as RTV-1 rubber) is one of the main products in the condensation type liquid silicone rubber. It is usually formulated from base polymer, crosslinker, catalyst, filler and additives. The product is packed in sealed hose, extruded when used, and can vulcanize itself into elastomer after contacting air, which is extremely convenient to use. Vulcanized rubber can be used for a long time in the temperature range of (-60 ~ 200 ℃), with excellent electrical insulation properties and chemical stability, water resistance, ozone resistance, weather aging resistance, a variety of metal and non-metallic materials have good adhesive properties. Mainly used as a variety of electronic components and electrical equipment coating, sealing material insulation, moisture-proof, shockproof role; as a semiconductor device surface protection materials; can also be used as a sealing gap filler and elastic adhesive.
One of the typical applications of silicone sealant is glass curtain wall. The glass and aluminum alloy frame with silicone structural adhesive bonding as the exterior wall materials, expansion joints with silicone weathering adhesive to do waterproof sealing. Other applications include perimeter sealing for aluminum alloy doors and windows and plastic steel doors and windows, glass installation and moving groove seams, rivets and fixing screws sealing: kitchen, bathroom, toilet sanitary ware and countertops, walls, waterproof sealing between furniture; aquariums, canopies, metal roofs, cabinets, windows, counters, siding, color steel sealing; for waterproof inlay sealing between high-grade highway panels and so on.
RTV in addition to construction sealant, but also for aerospace, nuclear power plants, electronics, machinery, automotive and other industries, sealing materials, used for electronic components potting silicone potting material, used as a soft mold material silicone mold adhesive and so on. The demand for these varieties is relatively small, but in many occasions is indispensable.