Silicone products have good resistance to high and low temperatures, and can generally work at 180 C for a long time. Silicone rubber can also work for a long time at 250 C. It can withstand high temperature of more than 1000 degrees Celsius instantaneously. Organosilicon materials have good low temperature resistance and can generally work at - 55 C. Some silicone rubber is still elastic at - 110 C. Silicone materials have good electrical insulation properties, dielectric properties do not change dramatically with temperature; dielectric constant does not increase with frequency; and arc resistance, corona resistance, leakage resistance; ozone resistance, radiation resistance, weather resistance, non-flammable, so they are widely used. Following
According to several categories of organosilicon products, some main uses of organosilicon products are briefly introduced respectively:
1. Silane coupling agent silane coupling agent is a kind of low molecular compound. One end of the silicon atom is connected with hydrolyzable chlorine or various alkoxy groups, which can be linked with inorganic substances after hydrolysis. The other end has various functional groups which can interact with organic substances, such as amino, vinyl, mercapto, etc., so silane coupling agent can bridge organic substances and inorganic substances. There are nearly 100 kinds of silane coupling agents in common use. For example, glass fibers used in FRP should be treated with vinyl-containing coupling agents to improve wet strength. At present, the popular "green" tires use a large number of silane coupling agents containing mercapto group; polyethylene crosslinked with vinyl trialkoxysilane can work at a higher temperature than ordinary polyethylene and polyvinyl chloride, which is suitable for hot water pipes, cable sheaths and so on.
2. Silicone oil silicone oil is a low molecular polysiloxane with single or different organic groups, which can be made into various viscosities. Silicone oil is a high quality water repellent material with low surface tension and large contact angle with water. Silicone oil is the base oil of gyroscope oil, antifreeze and heat-resistant lubricating oil, hydraulic oil, instrument oil, and high vacuum diffusion pump oil with very low vapor pressure. The application of organosilicon oil or its modified agents in cosmetics has increased rapidly in recent years. Silicone oil is not greasy or greasy on the skin. It feels smooth and comfortable. It can be made into various skin creams.
3. According to the vulcanization mechanism, silicone rubber can be divided into HTV, RTV and LSR, which have the properties of heat resistance, cold resistance, ozone resistance, ultraviolet radiation resistance, atomic oxygen resistance, cosmic ray resistance, water proof and shock resistance. LSR liquid silicone rubber (also known as silicon gel) is an excellent potting and protection material for semiconductor chips and electronic devices. The silicone gel with transmittance of up to 91% is the middle adhesive layer of the three windshield glass that requires high temperature, moisture resistance and non yellowing. LSR silicone rubber mould adhesive is used for precision casting of engine parts. The production of HTV and RTV accounts for a large proportion (generally 40%-50%) of organic silicon products, and HTV is more widely used than RTV.
(1) RTV room-temperature cured silicone rubber RTV is usually made of hydroxyl-terminated low molecular polysiloxane (107 gum), catalyst, filler and so on. It is easy to use and can be cured at room temperature. It has good adhesion to glass, ceramics, metal, concrete and other materials, and is widely used in all-field glass curtain wall, aluminum alloy doors and windows and other structural parts. The seals are bonded and sealed, as well as leak stoppage and seams in the bathroom and bathroom of the family. RTV silicone rubber-based ablative thermal insulation coating has low thermal conductivity and is easy to construct. It is used for rocket nozzle and return spacecraft to avoid ablation. It is also an important material for making spacecraft components. RTV silicone rubber is also a flexible die for various artistic decorative carving materials.
(2) HTV high temperature vulcanized silicone rubber HTV is a high molecular weight (400,000-800,000) polysiloxane. It is vulcanized and formed into rubber by adding reinforcing fillers and other additives. HTV silicone rubber composite insulator for high voltage power transmission and transformation not only has 1/5 to 1/10 weight of ceramic insulator, but also has good pollution flashover resistance and can safely operate in high voltage power transmission and transformation network. HTV silicone rubber, which uses carbon black as conductive medium, is widely used as key pad on keyboards of mobile phones and computers. Silicone rubber is widely used to make shaft seals, gaskets, oil seals, industrial rubber rollers, shock absorbers, insulating products, medical products, etc. Silicone rubber insulated refractory wires and cables are used in warships, airplanes and other places requiring high reliability. Silicone rubber has the characteristics of physiological inertia, non-coagulation, simple disinfection and so on. It can be used to make silicone rubber parts that can be implanted into human body and various silicone rubber catheters, intubations, hydrocephalus drainage tubes, peritoneal dialysis tubes, and artificial cardiopulmonary machine blood transfusion pump tubes. In addition, silicone rubber has air permeability and different permeability to different gases. Oxygen permeability is the highest in synthetic polymers, which can be used as oxygen-enriched membrane and gas separation membrane.
4. The insulating material made of silicone resin and silicone resin belongs to class H because of its good heat resistance and insulation performance. The motor made of silicone resin and silicone resin has small volume, light weight and high reliability, and can not burn out under short-term overheating and overload. Silicone resin can be used to prepare high temperature coatings at 500 C. Silicone modified acrylic resin coatings have good weather resistance, hydrophobicity and pollution resistance, and are high-grade exterior wall coatings. Silicone plastic made of silicone resin can be used as a high voltage, high current and arc resistant micro-switch for aircraft engines. In a word, silicone materials are widely used and have remarkable effects.
5. There are many kinds of organosilicon products, which can be roughly divided into five categories, namely
(1) The most commonly used high temperature vulcanized silicone rubber are methyl vinyl silicone rubber, cold-resistant phenyl silicone rubber, oil-resistant, solvent-resistant fluorosilicone rubber and nitrile silicone rubber, radiation-resistant styrene silicone rubber, etc. In order to facilitate the use of commonly prepared rubber mixtures to provide users.
(2) Room temperature vulcanized silicone rubber can be divided into two components and one component according to the packaging form. Two components are divided into methyl, phenyl, silicon nitrile, fluorosilicon and phenylene; one component is divided into deacidification type, deacidification type, deamination type, deamidation type, deacidification type, etc.
(3) Silicone oil silicone oil can be divided into methyl silicone oil, ethyl silicone oil, methyl phenyl silicone oil, amino silicone oil, methyl hydrogen silicone oil, chlorophenyl silicone oil, fluorosilicone oil, nitrile silicone oil, long chain alkane silicone oil, diffusion pump oil and modified silicone oil. There is a large amount of silicone oil processing products, namely silicone oil emulsion, such as fabric treatment agent is an example.
(4) Silicone resin can be divided into methyl silicone resin and methyl phenyl silicone resin according to its composition, and solvent-free silicone resin according to its morphology. Silicone resins are also made into coatings, moulding powders and modifications.
(5) Silane coupling agents are classified according to functional groups. Silane coupling agents mainly include vinyl silane, amino silane, epoxy silane, mercapto silane and methacryloxy silane.