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Oil-resistant and special-medium-resistant fluorine rubber seals

Oil-resistant and special-medium-resistant fluorine rubber seals

2022-10-31


  Fluorine rubber has a high degree of chemical stability and is one of the best medium resistance among all elastomers at present. Type 26 fluororubber is resistant to petroleum-based oils, diester oils, silicone ether oils, silicic acid oils, inorganic acids, most organic and inorganic solvents, pharmaceuticals, etc., only low molecular weight ketones, ethers, Ester, not resistant to amine, ammonia, HF, ClSO2OH, phosphoric acid hydraulic oil. The dielectric properties of type 23 fluorine rubber are similar to those 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. It is immersed in 98% HNO3 at room temperature. Its volume expansion is only 13% to 15%.


Excellent high temperature resistance


The high temperature resistance of fluororubber is the same as that of silicone rubber, which can be said to be the best among the current elastomers. 26-41 fluorine rubber can be used for a long time at 250 ℃ and short-term use at 300 ℃; 246 fluorine rubber has better heat resistance than 26-41. The physical properties of 26-41 after air thermal aging at 300℃×100 hours are equivalent to those of 246 type after 300℃×100 hours hot air aging. Its elongation at break can be maintained at about 100%, and the hardness is 90~95 degrees. . Type 246 retains good elasticity after 16 hours of hot air aging at 350°C, retains good elasticity after 110 minutes of hot air aging at 400°C, and contains spray carbon black, thermal carbon black or carbon fiber after 110 minutes of hot air aging at 400°C The elongation of the rubber compound increases by about 1/2~1/3, and the strength decreases by about 1/2, but still maintains good elasticity. 23-11 type fluorine rubber can be used for long-term use at 200℃ and short-term use at 250℃.


Good aging resistance


Fluorine rubber has excellent weathering resistance and ozone resistance. According to reports, the VitonA developed by DuPont is still satisfactory after ten years of natural storage, and there is no obvious cracking in the air with an ozone concentration of 0.01% for 45 days. Type 23 fluororubber has excellent weather resistance and ozone resistance.


Better vacuum performance


Type 26 fluororubber has excellent vacuum properties. The vacuum outgassing rate of the vulcanized rubber with the basic formula of 246 fluororubber is only 37×10-6 Torr liters/sec. Centimeter 2. 246 type fluororubber has been successfully applied under vacuum conditions of 10-9 Torr.


Excellent mechanical properties


Fluorine rubber has excellent physical and mechanical properties. Type 26 fluororubber generally has a strength between 10 and 20MPa, an elongation at break between 150 and 350%, and a tear strength between 3 and 4KN/m. Type 23 fluororubber has a strength of 15.0~25MPa, an elongation rate of 200%~600%, and a tear strength of 2~7MPa. In general, the compression deformation of fluororubber at high temperature is large, but if compared under the same conditions, such as the compression deformation of the same time at 150 ° C, the nitrile and neoprene rubber are larger than the 26 type fluororubber, and the 26 type The compression deformation of fluororubber at 200℃×24 hours is equivalent to the compression deformation of butadiene rubber at 150℃×24 hours.


better electrical performance


23 type fluororubber has better electrical properties and lower hygroscopicity than other elastomers, and can be used as a better electrical insulating material. Type 26 rubber can be used at low frequency and low pressure.


low air permeability


The solubility of fluororubber to gas is relatively large, but the diffusion rate is relatively small, so the overall air permeability is also small. According to reports, the air permeability of 26-type fluororubber to oxygen, nitrogen, helium, and carbon dioxide gas at 30 °C is comparable to that of butyl rubber and butadiene rubber, and is better than that of neoprene and natural rubber.


Poor low temperature performance


The low temperature performance of fluororubber is not good, which is due to its own chemical structure, such as Tg>0℃ of type 23-11. The low temperature performance of fluororubber actually used is usually expressed by the brittleness temperature and the compression cold resistance coefficient. The formula of the rubber compound and the shape of the product (such as thickness) have a great influence on the brittleness temperature. If the amount of filler in the formula increases, the brittleness temperature is sensitively deteriorated, and the thickness of the product increases, and the brittleness mixing degree is also sensitively deteriorated.


Poor radiation resistance


The radiation resistance of fluororubber is one of the poorer elastomers. Type 26 rubber exhibits a cross-linking effect after radiation, while type 23 fluororubber exhibits a cracking effect. The performance of 246 type fluorine rubber changes drastically under the dose of 5 × 107 lon in the air at room temperature. Under the condition of 1 × 107 lon, the hardness increases by 1~3 degrees, the strength drops below 20%, and the elongation decreases by 30%~50% , so it is generally believed that 246-type fluororubber can withstand 1 × 107 lons, and the limit is 5 × 107 lons.


Key applications


Because fluororubber has the characteristics of high temperature resistance, oil resistance, high vacuum resistance, acid and alkali resistance, and resistance to various chemicals, it has been used in modern aviation, rockets, astronautics, ships, atomic energy and other cutting-edge technologies as well as automobiles, shipbuilding, chemistry, petroleum, Telecommunications, instrumentation, machinery and other industrial fields.


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