Fluorine rubber refers to a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of the main chain or side chain. It not only has good mechanical properties, but also has high resistance to high temperature, oil and various chemicals. Its characteristics and comprehensive performance are particularly excellent, so it has a wide range of applications, especially for the production of special sealing products. Material.
1. Structural characteristics and application fields of fluororubber
Since there is no unsaturated C=C bond structure on the main chain of polyolefin fluororubber (type 26 fluororubber, type 23 fluororubber) and nitroso fluororubber. The possibility of degradation and chain scission on the main chain due to oxidation and pyrolysis is reduced. The methylene group in vinylidene fluoride plays a very important role in the flexibility of the polymer chain. For example, fluororubber 23-21 and fluororubber 23-11 are composed of vinylidene fluoride and chlorotrifluoroethylene at a ratio of 7:3 And the ratio of 5:5, obviously, the former is softer than the latter.
Whether it is vinylidene fluoride and chlorotrifluoroethylene, or the copolymer of the former and hexafluoropropylene, and the terpolymer of them and tetrafluoroethylene, they can be mainly crystalline or amorphous. This depends on the level of intervening of one monomer when the other is the main segment of the copolymer. Electron diffraction studies indicate that the two copolymers still have the same and The crystal structure of its equivalent homopolymer. However, when the molar fraction of hexafluoropropylene in the former increases to more than 15%, or the molar fraction of vinylidene fluoride in the latter increases to more than 25%, the lattice is greatly destroyed, resulting in them having a rubber-dominant amorphous shape structure. This is due to the increase in the amount of the second monomer introduced, which destroys the regularity of its original molecular chain. Fluorine rubber can be used in combination with nitrile rubber, acrylate rubber, ethylene propylene rubber, silicone rubber, fluorosilicone rubber, etc. to reduce costs and improve physical and mechanical properties and process performance.
The earliest fluororubber is poly-2-fluoro-1,3-butadiene and its copolymer with styrene and propylene, which was trial-produced by DuPont in the United States in 1948. Its performance is no better than that of chloroprene rubber and butadiene rubber. , and it is expensive and has no real industrial value. In the late 1950s, the American company Thiokol developed a binary nitroso fluororubber with good low temperature performance and strong oxidant resistance (N2O4). Fluorine rubber began to enter practical industrial applications.
Fluorine rubber is widely used in daily life, such as in auto parts, aviation and aerospace, mechanical seals, pumps, reactors, agitators, compressor housings, valves, various instruments and other equipment as valve seats , valve stem packing, diaphragm and gasket, as well as in the rubber sheet industry, semiconductor manufacturing industry and food and pharmaceutical industries.
With the use of unleaded gasoline and electronic fuel injection devices in automobiles, the structure and material of fuel hoses have changed greatly. The inner rubber layer has been replaced by fluororubber to replace nitrile rubber. In order to reduce fuel penetration and further improve heat resistance, internal The rubber layer mostly adopts a composite structure, that is, it is composed of fluororubber, chlorohydrin rubber or acrylate rubber. Because fluororubber is relatively expensive, the fluororubber layer is relatively thin, with a thickness of about 0.2 to 0.7 mm.
In terms of high-tech automotive engines, transmissions, and valve oil seals, the materials selected are mainly fluororubber, hydrogenated nitrile rubber, etc. Fluorine rubber and silicone rubber composite oil seals have become the most commonly used engine crankshaft oil seals. The hydraulic system of the loading and unloading truck and the hydraulic system of the large-scale loading and unloading truck have a long continuous working time, and the oil temperature and the temperature of the parts rise rapidly. The ordinary rubber cannot meet their working requirements, and the fluororubber products can meet various harsh requirements with their excellent temperature resistance. technical requirements. With the continuous improvement of the automotive industry's requirements for reliability and safety, the demand for fluororubber in the automotive industry has also shown a rapid growth trend. In addition to automotive industry applications, fluororubber seals are used in drilling machinery, oil refining equipment, natural gas and power plant desulfurization devices, and can withstand harsh conditions such as high temperature, high pressure, oil and strong corrosive media at the same time; in chemical production, fluororubber seals Parts are used in pumps and equipment containers to seal chemical substances such as inorganic acids and organics. In the petroleum and chemical industries, fluororubber sealing products are used in mechanical seals, pumps, reactors, agitators, compressor casings, valves, various instruments and other equipment, such as packings for valve seats, valve stems, and diaphragms. and gaskets. Fluorine rubber is one of the indispensable high-performance materials for cutting-edge science and technology such as modern aviation, missiles, rockets, astronautics, ships, and atomic energy. In recent years, new fluorine rubber products have been continuously developed in the field of aviation and aerospace.