Properties and application of the hottest fluororu

2022-07-27
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Properties and applications of fluororubber fluororubber has the characteristics of high temperature resistance, oil resistance and resistance to erosion by a variety of chemicals. It is an indispensable material for modern aviation, missiles, rockets, space navigation and other cutting-edge science and technology. In recent years, with the increasing requirements of automobile industry for reliability and safety, the consumption of fluororubber in automobiles has also increased rapidly

fluororubber refers to a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of the main chain or side chain. The earliest fluororubber was poly-2-fluoro-1.3-butadiene and its copolymers with styrene, propylene, etc. produced by DuPont company in 1948. However, its performance is not more outstanding than that of neoprene and butadiene rubber, and its price is expensive, so it has no actual industrial value. In the late 1950s, Thiokol company of the United States developed a kind of binary nitroso fluororubber with good low temperature performance and resistance to strong oxidant (N2O4), and fluororubber began to enter practical industrial application. Since then, with the technological progress, various new fluororubbers have been developed

since 1958, China has also developed a variety of fluororubbers, mainly polyolefin fluororubbers, such as 23, 26, 246 and nitroso fluororubbers; Later, more new varieties of tetrapropyl fluororubber, perfluoroether rubber and fluorinated phosphorus rubber were developed. These fluororubber varieties have been gradually popularized and applied to civil industrial sectors based on the needs of aviation, aerospace and other national defense and military industries

main properties

good chemical stability

fluororubber has high chemical stability and is the best medium resistance among all elastomers at present. Type 26 fluororubber is resistant to petroleum based oil, di ester oil, silicone ether oil, silicic acid oil, inorganic acid, most organic and inorganic solvents, drugs, etc., only low molecular ketones, ethers and esters, and amine, ammonia, hydrofluoric acid, chlorosulfonic acid and phosphoric acid hydraulic oils. The medium performance of type 23 fluoroadhesive is similar to that of type 26, and it is more unique. Its resistance to strong oxidizing inorganic acids such as fuming nitric acid and concentrated sulfuric acid is better than that of type 26. Its volume expansion is only 13%~15% after 27 days of immersion in 98% HNO3 at room temperature

excellent high temperature resistance

fluororubber has the same high temperature resistance as silicone rubber, which can be said to be the best elastomer at present. Fluorine glue can be used for a long time at 250 ℃, and most private enterprises in 3 industries can be used for a short time at 00 ℃; The heat resistance ratio of 246 fluororubber is better. At 300 ℃ × Physical properties after 100 hours' air thermal aging and 300 ℃ × After 100 hours of hot air aging, the performance of type 246 is equivalent, its elongation at break can be maintained at about 100%, and its hardness is 90~95 degrees. Type 246 maintains good elasticity after 16 hours of aging in hot air at 350 ℃, and 110 minutes after aging in hot air at 400 ℃. After 110 minutes of aging in hot air at 400 ℃, the elongation of the compound containing spray carbon black, hot cracking carbon black or carbon fiber increases by about 1/2~1/3, and the strength decreases by about 1/2, still maintaining good elasticity. (2) What is the type approval and type evaluation fluoroadhesive that can be used for a long time at 200 ℃ and for a short time at 250 ℃

good aging resistance

fluororubber has excellent weather aging resistance and ozone resistance. It is reported that the performance of vitona developed by DuPont is still satisfactory after ten years of natural storage, and there is no obvious cracking after 45 days in the air with 0.01% ozone concentration. Type 23 fluororubber has excellent weather aging resistance and ozone resistance

excellent vacuum performance

26 fluororubber has excellent vacuum performance. The vacuum outgassing rate of vulcanizate of 246 fluororubber basic formula is only 37 × Torr L/s. cm2. 246 fluororubber has been successfully used in Torr vacuum

excellent mechanical properties

fluororubber has excellent physical and mechanical properties. The general matching strength of type 26 fluororubber is 10~20mpa, the elongation at break is 150~350%, and the tear strength is 3~4kn/m. The strength of type 23 fluororubber is 15.0~25mpa, the elongation is 200%~600%, and the tear strength is 2~7mpa. Generally, the compression set of fluororubber at high temperature is large, but if compared under the same conditions, for example, from the compression set at 150 ℃ for the same time, both butadiene and neoprene are larger than 26 fluororubber, and 26 fluororubber is at 200 ℃ × The compression deformation under 24 hours is equivalent to that of butadiene rubber at 150 ℃ × 24 hours compression deformation

good electrical properties

23 fluororubber has good electrical properties and lower moisture absorption than other elastomers. It can be used as a good electrical insulation material. Type 26 rubber can be used under low frequency and low pressure

low permeability

fluororubber has high solubility in gas, but its diffusion speed is relatively small, so the overall permeability is also small. It is reported that the permeability of type 26 fluororubber to oxygen, nitrogen, helium and carbon dioxide at 30 ℃ is equivalent to that of butyl rubber and butadiene rubber, and better than that of neoprene and natural rubber

poor low temperature performance

the poor low temperature performance of fluororubber is due to its own chemical structure, such as type TG> 0 ℃. The low temperature performance of fluororubber used in practice is usually expressed by brittle temperature and compression cold resistance coefficient. The formula of the compound and the shape (such as thickness) of the product have a great impact on the brittleness temperature. If the amount of filler in the formula increases, the brittleness temperature will be sensitive to deterioration, and the thickness of the product will increase, and the brittleness mixing degree will also be sensitive to deterioration

poor radiation resistance

the radiation resistance of fluororubber is one of the worse elastomers. Type 26 rubber shows crosslinking effect after radiation, while type 23 fluororubber shows cracking effect. 246 fluororubber in air at room temperature radiation of 5 × The performance changed dramatically at the dose of 107 Lun, and × The hardness increases by 1~3 degrees, the strength decreases by less than 20% and the elongation decreases by 30%~50% under the condition of 107. Therefore, it is generally considered that 246 fluororubber can withstand 1 × 107 Lun, limit 5 × 107 Lun

key application

due to the characteristics of high temperature resistance, oil resistance, high vacuum resistance, acid and alkali resistance, and resistance to a variety of chemicals, fluororubber has been applied to advanced technologies such as modern aviation, missiles, rockets, space navigation, ships, atomic energy, and industrial fields such as automobile, shipbuilding, chemistry, petroleum, telecommunications, instrumentation, machinery, etc

typical application

fluororubber seals can work at 200 ℃ ~250 ℃ for a long time and at 300 ℃ for a short time when used for engine sealing. Their service life can be the same as the engine repair life, up to 1000~5000 flight hours (5~10 years); When used in the chemical industry, it can seal inorganic acids (such as 67% sulfuric acid at 140 ℃, concentrated hydrochloric acid at 70 ℃, and 30% nitric acid at 75 ℃), organic solvents (such as chlorinated hydrocarbons, benzene, high aromatic gasoline) and other organic substances (such as butadiene, styrene, propylene, phenol, fatty acids at 275 ℃); When used for deep well oil production, it can withstand the harsh working conditions of 149 ℃ and 420 atmospheres; When used for superheated steam seals, it can work in steam medium of 160~170 ℃ for a long time. In the production of monocrystalline silicon, fluororubber seals are commonly used to seal special media at high temperature (300 ℃) - trichlorosilane, silicon tetrachloride, gallium arsenide, phosphorus trichloride, trichloroethylene and 120 ℃ hydrochloric acid

for high vacuum applications, when the flight altitude is 200~300km, the air pressure is 133 × PA (mmHg), neoprene, butadiene rubber and butyl rubber can be used; When the flight altitude exceeds 643km, the air pressure will drop to 133 × Below PA (mmHg), only fluororubber can be used in this high vacuum air. Generally, before the high vacuum or ultra-high vacuum device system is used, it needs to undergo high (4) anti-corrosion temperature baking treatment. Type 26 and type 246 fluororubber can withstand high temperature aging of 200 ℃ ~250 ℃, so it has become the most important rubber material in high vacuum equipment and spacecraft

the hose made of fluororubber is suitable for high temperature resistant, oil resistant and special media resistant occasions, such as the transportation and guidance of aircraft fuel oil, hydraulic oil, synthetic diester oil, high temperature hot air, thermal inorganic and other special media (such as chlorinated hydrocarbons and other chlorides). The wires and cables made of fluororubber have good flexibility and good insulation. The glass fiber adhesive tape made of fluororubber can withstand 300 ℃ high temperature and chemical corrosion. After the aramid cloth is coated with fluorine glue, it can be used to make the connecting expansion pipe between the high-temperature, acid and alkali resistant storage tanks in petrochemical plants (both ends can be connected with metal flanges), which can withstand high pressure, high temperature and medium corrosion, and play the role of buffer and shock absorption connection for the deformation and expansion of the two tanks. The adhesive tape sealing bag made of nylon cloth coated with fluorine glue is used as the soft sealing element for the inner floating roof storage tank in the refinery, which plays the role of sealing and reducing the volatilization loss of oil level

23 and tetrapropyl fluororubbers are mainly used for acid resistant and special chemical resistant corrosive sealing occasions. Hydroxynitroso fluororubber is mainly used as protective products and sealing products, and as a non combustible coating in the form of solution. It is applied to fire-proof electronic components and components working in pure oxygen. Its solution and liquid rubber can be sprayed, poured and other methods to produce many products, such as spacesuit, gloves, pipe belts, balls and so on. It can also be used as an adhesive for glass, metal and fabric, and can be used to manufacture sponges and gaskets contacting rocket propellant (N2O4), "O" rings, capsules, valve seals, etc

g series fluororubber seals have the properties of high temperature vapor resistance, methanol gasoline resistance or gasoline containing high aromatic hydrocarbons that vitona, B, e and other fluororubbers cannot achieve; GLT fluororubber, chlorinated phosphorus rubber, perfluoroether rubber, etc. have a wider temperature range, low softness, elastic sealing, etc. Perfluoroether rubber also has outstanding medium corrosion resistance and is widely used in military cutting-edge technology

the sealant putty made of fluororubber has outstanding fuel oil resistance. It can be used in oil at about 200 ℃ and is used as the sealing material of the aircraft's overall fuel tank. The closed cell sponge made of fluororubber has acid resistance, oil resistance, wide service temperature range and good insulation. It can be used as the sealing of rocket fuel, solvent, hydraulic oil, lubricating oil and grease, and the damping material of rocket and missile. The temperature resistance can reach 204 ℃, and the asbestos fiber cloth impregnated with fluororubber lotion can be made into asbestos rubber plate, which can be used in the occasions of high temperature resistance, combustion resistance and chemical corrosion resistance

automotive industry

in recent years, with the rapid development of the automotive industry, the temperature of the automotive engine room has increased, and the use of modified fuel and highly corrosive engine fuel has become increasingly common. Fluororubber is more widely used as automotive sealing materials than ever before

in order to improve the power of automobile engine, save fuel and ensure the safety of automobile driving, a new fuel injection system appears. In this system, the car flows into the engine from the fuel tank, and then returns to the fuel tank for circulation. The mixture of gasoline and oxygen will produce a computer hydroperoxide. Gasoline containing hydrogen peroxide is called "acid gasoline", which can soften or harden a variety of hydrocarbon rubbers. However, fluororubber will not deteriorate due to contact with acid gasoline. Table 1 penetration rate of fuel C

countries all over the world formulate new environmental protection regulations every year. The total hydrocarbon emission of automobile is increasingly restricted, and the automobile industry is more and more difficult to meet this requirement. In the United States, vehicles must pass the shed (sealed box evaporation measurement) test. Fluororubber has excellent barrier to hydrocarbon penetration (Table 1). Coating the fuel hose structure with fluororubber layer can reduce the amount of hydrocarbon penetration

automotive fuel system

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