According to its vulcanization temperature, liquid silicone can be divided into two categories: high-temperature (heating) vulcanization type and room temperature vulcanization type. High-temperature silicone is mainly used to manufacture various silicone rubber products, while room-temperature silicone is mainly used to manufacture various silicone rubber products. Used as adhesive, potting material or mold.
(2) Room temperature vulcanized silicone rubber (RTV) (1) Thermal vulcanized silicone rubber (HTV)
Thermal vulcanized silicone rubber (HTV) is the most important part of silicone products Class, methyl vinyl silicone rubber (VMQ) is the most important variety in HTV, commonly known as high temperature glue.
Methyl vinyl silicone rubber (raw rubber) is a colorless, odorless, non-toxic, and mechanically impurity-free gel. Appropriate reinforcing agents, structure control agents, and Vulcanizing agents and other additives are mixed together, then heated to molding or extrusion molding, and then made into various products through two-stage vulcanization. Its products have excellent electrical insulation, strong resistance to arc, corona, and sparks, are waterproof, moisture-proof, impact-resistant, and shock-resistant, and have physiological inertness, breathability and other properties.
Mainly used in aviation, instrumentation, electronic appliances, navigation, metallurgy, machinery, automobiles, medical and health and other departments. It can be used to make seals, gaskets, tubes, cables of various shapes, and can also be used to make human bodies. Organs, blood vessels, breathable membranes and rubber molds, release agents for precision casting, etc.
Room temperature vulcanized silicone rubber generally includes two categories: condensation type and addition type.
Addition room temperature glue is based on linear polysiloxane with vinyl groups and hydrogen-containing siloxane as cross-linking agent. The cross-linking reaction occurs at room temperature to medium temperature in the presence of a catalyst. and become an elastic body. It has good heat resistance, hydrophobicity, and electrical insulation. At the same time, due to the introduction of active end groups, it has excellent physical and mechanical properties, especially in tensile strength, relative elongation and tear strength. improvement. It is suitable for a variety of vulcanization methods, such as radiation vulcanization, peroxide vulcanization and addition vulcanization. It is widely used in heat resistance, moisture resistance, electrical insulation, high-strength silicone rubber products, etc.
Two-component room temperature vulcanized silicone rubber (RTV-2 rubber for short) is not as convenient to use as RTV-1 rubber, but its component proportions are highly variable. One variety can produce vulcanized products with various specifications and properties. , and can also be deeply vulcanized, so it is widely used in electronic appliances, automobiles, machinery, construction, textile, chemical industry, light industry, printing and other industries for insulation, packaging, caulking, sealing, moisture-proof, earthquake-resistant and roller making materials . In addition, because RTV-2 has excellent mold release properties, it is widely used as a soft mold material in the reproduction and manufacturing of cultural relics, handicrafts, toys, electronic appliances, mechanical parts, etc.
Condensation type room temperature vulcanized silicone rubber is characterized by the condensation reaction between silicone hydroxyl groups and other active substances. It can be cross-linked into elastomer silicone rubber at room temperature. The product is divided into single-component packaging. and two-component packaging forms. One-component room temperature vulcanized silicone rubber (RTV-1 rubber for short) is one of the main products of condensation liquid silicone rubber. It is usually formulated from base polymer, cross-linking agent, catalyst, filler and additives. The product is packaged in a sealed hose and extruded during use. It can self-vulcanize into an elastomer when exposed to air, making it extremely convenient to use. Vulcanized rubber can be used for a long time in the temperature range of (-60~200℃), has excellent electrical insulation properties and chemical stability, is resistant to water, ozone, weather aging, and has good bonding to a variety of metal and non-metal materials. sex. It is mainly used as a coating for various electronic components and electrical equipment. The encapsulation material plays the role of insulation, moisture-proof and shock-proof; as a surface protection material for semiconductor devices; it can also be used as a sealing gap filler and elastic adhesive.
One of the typical applications of silicone sealants is glass curtain walls. The glass and aluminum alloy frames are bonded with silicone structural adhesive as exterior wall materials, and the expansion joints are waterproofed and sealed with silicone weather-resistant adhesive.
Other applications include peripheral sealing of aluminum alloy doors and windows and plastic steel doors and windows, sealing of glass installation and moving troughs, rivets and fixing screws: sanitary ware and countertops, walls and furniture in kitchens, bathrooms and toilets. Waterproof sealing between aquariums, ceilings, metal roofs, showcases, counters, wall panels, and color steel plates; used for waterproof caulking sealing between high-grade highway sections, etc.
In addition to construction sealants, RTV also includes sealing materials used in aerospace, nuclear power plants, electronics, machinery, automobiles and other industries, and silicone potting materials used for potting electronic components. Silicone mold glue used as soft mold material, etc. These varieties are in relatively small demand, but are indispensable on many occasions.