The application field of high temperature vulcanized silicone rubber

High temperature vulcanization

High temperature vulcanized silicone rubber raw rubber can be formulated into a solution for release agent and release agent in rubber, plastic products, precision casting and food industry. Compared with silicone oils for similar purposes, it has the characteristics of less fluidity. It is non-toxic, efficient, heat-resistant, and can make the surface of the product bright and clear. Silicone rubber containing fillers and other additives can be used as putty in the unvulcanized state. But the main forms of use of silicone rubber are various vulcanized products, including molded products (such as various rubber sheets, gaskets, gaskets, leather bowls, valves, thin waxes, shock absorbers, electrical plugs, rubber rollers, potentiometer insulation sleeves, waveguides, heating sheets, conductive buttons and various medical products, such as cartilage, pacifiers, etc.), extrusion products (such as various rubber tubes, rubber ropes, profiles, wire sheathing, cable sheathing, rubber strips, self-adhesive Silicone rubber tape, etc.), coated products (gaskets, diaphragms, self-adhesive cloth, isolation cloth, etc.). Because silicone rubber vulcanized products have excellent comprehensive properties and good technical and economic effects, they are mostly used in occasions requiring high temperature and low temperature resistance, as well as for non-stick surfaces, or good electrical insulation properties, especially at high and low temperatures. , high frequency and some occasions where good electrical performance is still required under harsh conditions. Therefore, it has been widely used in aviation, aerospace, automobile, electronics, electrical appliances, chemical industry, instrumentation, machinery and other industrial sectors, as well as in agriculture, medical care and daily life. application.

Application of Silicone Rubber in Automobile and Machinery Industry

In addition to tires, the rubber products on a modern car also include various rubber hoses, sealing rings, oil seals, leather cups, wiper strips, dust covers, buffer rings and other rubber parts. There are nearly 550 types of rubber used. There are also many varieties, and silicone rubber is one of them. Due to the development of automobile engines in the direction of high power and miniaturization, the temperature around the engine is often as high as 315 ℃, and the temperature near the gearbox also exceeds 175 ℃. Therefore, general organic rubber products can no longer withstand such high temperatures and various properties such as oil resistance, chemical resistance, and aging resistance. And silicone rubber can play a role in these aspects, therefore, the amount of silicone rubber in automobiles has grown rapidly. In addition, the price gap between silicone rubber and other special synthetic rubbers has gradually narrowed in recent years, which has also promoted the growth of the silicone rubber market.

Silicone rubber can withstand the high temperature under the car cover, so that it is still strong after years of weather aging and vibration and abrasion, can withstand the damage of fuel, lubricating oil and dust, and can adapt to the electrical requirements under harsh conditions. Ideal for many uses under the hood, helping to reduce maintenance costs and driving failures. Specific applications such as: spark plug caps, ignition cable jackets, electrical connectors, radiator and heater hoses, seals, o-rings , Diesel engine gaskets, light gaskets, front wheel drive bushings, rotary shaft seals, seals for hydraulic transmissions, and a blend of magnesium oxide silicone rubber or fluorosilicone rubber and general-purpose silicone rubber can be used as oil seals.

In the machinery industry, the biggest use of silicone rubber is for shaft seals and cup seals that contact dynamic parts such as shafts and pistons. Due to the small coefficient of friction of silicone rubber, it can be used for machine parts that operate at high speeds.

Silicone rubber can also be used to seal structural components in high temperature furnaces and low temperature refrigerated trucks. Rubber rollers made of silicone rubber are heat-resistant and non-stick, and are suitable for metal sheets, glass objects and ceramic devices that transport heat.

Application of silicone rubber in wire and cable industry

Due to the good heat resistance of silicone rubber, for cables with the same cross-section, using silicone rubber instead of ordinary insulating materials can withstand 90% of the overload current. In the case of narrow equipment space or temporary overload, the use of silicone rubber insulated cables is very important.

Silicone rubber has good arc resistance and is relatively stable to corona discharge. In the case of corona discharge, the cable insulated with silicone rubber can be used continuously for 1000 hours, while the cable insulated with general organic rubber can only be used for 30 minutes. In addition, the changes of temperature and frequency have little effect on the electrical insulating properties of silicone rubber.

When the silicone rubber insulator breaks down or burns and decomposes, non-conductive silica residue is generated, which still has an insulating effect.

In environments with high-voltage electrical equipment, ozone is often generated due to high-voltage discharge. It will damage the insulation layer of ordinary rubber insulated cables and lose the ability to work normally. The ozone resistance of silicone rubber is similar to that of mica, so the cables insulated with silicone rubber will not be affected.

Compared with ordinary insulating materials, silicone rubber also has better thermal conductivity and can quickly dissipate the heat generated by the current load.

At present, the wires and cables insulated with silicone rubber include: electronic cables, ship cables, heating cables, ignition cables, aviation wires, atomic energy device cables, etc. In addition, the wires insulated with silicone rubber are also widely used in the connection of radio engineering equipment, the lead wires of H-class motors and transformers, the power supply wires of various electrical appliances and accessories, the high-voltage lead wires of TV sets and various lighting circuits.

Application of silicone rubber in electronics and electrical industries

In the electronics and electrical industries, silicone rubber is widely used as electrical connectors, electrical seals and shock absorbers, insulating tapes for motor stator coils, high temperature potentiometer seals, and thrust rings for motor high-voltage coils, etc. Carbon powder or carbon fiber, etc. Conductive silicone rubber made of conductive fillers is widely used as a conductive connector for various electronic and electrical equipment, and it can closely adhere to the contact surface of the contact. Key buttons made of this conductive silicone rubber are widely used in televisions, electronic computers, telephones, electronic organs and other electrical appliances. It has many advantages: no vibration, reliable reception and input of signals, thinning of products, etc. Various gaskets and sealing rings made of conductive silicone rubber are suitable for sealing and shielding microwave tubes and microwave oven flanges. It is also used in electronic watches, conductive connecting sheets in liquid crystal display sheets in electronic clocks, fax machines and leadless integrated circuits, and as anti-radiation electromagnetic shielding materials.

Silicone rubber reinforced with polyester fibers can be made into insulators in power transmission lines. Compared with ceramic insulators, it has the characteristics of light weight, high efficiency, good anti-arcing, anti-salt fog, dust and soil pollution flashover.

Heat-shrinkable silicone rubber is a new type of material with special coordination. It can be used for connection, protection and insulation of various electrical equipment. It has the characteristics of rapid operation and simple construction.

The high-voltage cap of the TV is an important accessory of the TV, and its quality directly affects the service life of the TV. The high-voltage cap made of silicone rubber not only has excellent high temperature resistance and electrical insulation, but also ozone resistance, thus ensuring the safety and reliability of the continuous work of the TV.

Application of Silicone Rubber in Aerospace and Aerospace Industry

Silicone rubber is the darling of rubber in the aviation and aerospace industries and has a wide range of uses. The first human footprint on the moon was a space boot print made of silicone rubber. Silicone rubber can be used to make various rubber hoses, sealing gaskets and gaskets in aircraft and rockets, and can also be used as buffer shockproof layers, hot air ducts, switch expansion sleeves, oxygen masks, hoses for starting jet engines, and shock absorbers for heat sinks , leather cups for braking devices, gaskets for various pipe hoops, fire baffles, hoses and cushions for instruments and meters, aviation wires and cables, electrical plugs, sockets, switch buttons, etc.

The flying environment of modern supersonic aircraft is very harsh, requiring various rubber parts on the aircraft to work for a long time in the range of -75 to +200 °C, and to have the ability to resist ozone. Under such harsh conditions, the general organic rubber is quickly and completely damaged. The silicone rubber still maintains its performance basically unchanged. A large number of electrical equipment on the aircraft are connected by wires and cables insulated with silicone rubber. These products not only have excellent high and low temperature resistance and aging resistance, but also have no corrosion to metals and have flame retardant effects. Therefore, various electrical equipment can be guaranteed to work safely and reliably.

In short, silicone rubber parts are widely used in aircraft. The amount is also very considerable. According to reports, a Boeing 707 aircraft needs to use 500 kg of silicone rubber, and an XB70 aircraft needs 1,000 kg of silicone rubber.

In aerospace, silicone rubber is also widely used. When various space vehicles enter the atmosphere at a high speed or fly in the atmosphere at a high speed, the vehicles have to do considerable resistance work to the surrounding medium. The ultimate manifestation of this resistance work is a large increase in heat. Part of this heat will be transferred to the surface of the aircraft, which will raise the temperature of the surface of the aircraft to more than 100℃. In this way, most of the metal will melt and the spacecraft will not be able to return to the ground. Therefore, some necessary thermal protection measures must be taken to keep the internal structure of the spacecraft and other payloads under the allowable temperature. Silicone rubber containing phenolic resin is an ideal ablative material to meet the above heat protection requirements.

Application of silicone rubber in medical and health

Because silicone rubber is non-toxic, odorless, physiologically inert, biologically aging, and has little response to human tissue, it will not cause foreign body reaction after implantation in the human body, and will not cause inflammation to surrounding tissues, so it is widely used in medical and health care. Such as surgical hoses and parts: blood vessels, pressure relief tubes, thoracic drainage tubes, gastroscope cannulas, intravenous cannulae, artificial heart-lung machine pump tubes, nasal cannulae, etc., which can withstand high temperature sterilization and maintain their Physical properties remain unchanged.

Silicone rubber has also begun to be widely used in cosmetic and prosthetics. Such as the use of silicone rubber to repair facial defects, nose, chin, jaw, neck, treatment of external ear defects and repair of internal organs, etc., as well as women’s artificial breast implantation.

Silicone rubber can also be used to make artificial organs, such as artificial heart spherical mitral valve, esophagus, trachea, arterial valve, artificial joints, artificial muscle keys, etc.

Silicone rubber also plays an active role in family planning and women’s health care. For example, silicone rubber shield-shaped IUDs, pessaries, fetal suction tips, and baby pacifiers have a smooth surface, are easy to clean, and can be sterilized at high temperatures without damage.

Silicone rubber and nylon fabric composite artificial meninges can be used to repair traumatic dura mater defects; microfiber cloth coated with silicone rubber can be made into artificial skin, which can be used for the rescue of patients with large-area burns and achieve satisfactory results; The artificial larynx made of torn silicone rubber replaces the cartilage in the laryngectomy operation. It can restore the functions of speech, eating and breathing for patients.

Because silicone rubber has good air permeability and selective air permeability (the diffusion coefficient of carbon dioxide gas is 6-7 times higher than that of oxygen), it is used in the oxygenation of blood. Silicone rubber can also be made into capsules, which can release various drugs (such as anticancer drugs, anesthetics, sedatives, etc.). Also used for long-acting contraception.

Silicone rubber in other applications

Because the molecular structure of silicone rubber is in the shape of a coil spring, its film products and air permeability are hundreds to dozens of times larger than ordinary organic films (such as polyethylene, etc.), and it is also selectively breathable to oxygen, carbon dioxide and other gases. Therefore, the silicone rubber film can be made into an air-conditioning window for storing fruits, vegetables, grains, etc., inhibiting the respiratory metabolism of fruits and vegetables, reducing the activity of enzymes, so as to achieve the purpose of prolonging storage time and preserving freshness.

Using the characteristics of silicone rubber surface heat, non-stick, low compression permanent deformation, it can be made into various silicone rubber rubber rollers, which are widely used in the printing industry and office machinery such as copiers and fax machines. For example: the surface of high-grade prints is covered with a layer of resin. It not only makes the prints bright and spectacular, but also waterproof and wear-resistant. However, in the process of printing casting, calendering or lamination, the molten resin is easy to adhere to the surface of ordinary rubber rollers, making the process impossible or seriously affecting the quality. If the rubber roller made of silicon rubber chamber is used, the phenomenon of molten resin sticking to the roller can be solved. This silicone rubber roller is also widely used for gluing and calendering of textiles.

Using the characteristics of high temperature resistance, steam resistance and physiological inertness of silicone rubber, it can be used as air pressure thermos and sealing ring, pressure cooker gasket, etc., which can greatly prolong the life.

Silicone rubber is made into capsules and can also be used for slow release of pesticides and fertilizers. Prolong drug efficacy and improve fertilizer efficiency.

Silicone rubber strips can be used to seal aluminum alloy doors and windows in high-end buildings, with good elasticity and weather resistance. The use of this sealing strip can reduce maintenance costs.

The anti-stick conveyor belt made of silicone rubber can be used for high temperature conveying of food and other viscous materials.