Jiangsu Frechem Co.,Ltd

Fluoroelastomer binary copolymer, DuPont grade VITON A, is a metafluoroethylene and hexafluoropropylene copolymer, with good comprehensive performance.
Fluoroelastomer ternary copolymer, DuPont grade VITON B, is a vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene terpolymer, fluorine content is higher than binary rubber, good solvent resistance.
Good stability
Fluoroelastomers have a high degree of chemical stability and are currently the best media resistance of any elastomer. Binary fluoroelastomer resistant to petroleum-based oils, diester oils, silicone ether oils, silicic acid oils, resistant to inorganic acids, resistant to most organic, inorganic solvents, pharmaceuticals, etc., only resistant to low molecular weight of ketones, ethers, esters, not resistant to amines, ammonia, hydrofluoric acid, chlorosulfonic acid, phosphate hydraulic oil.
High temperature resistance
The high temperature resistance of fluoroelastomer is the same as that of silicone rubber, which can be said to be the best in the current elastomer. Binary fluorine glue can be used for a long time at 250 °C and short-term use at 300 °C; ternary fluorine glue is heat-resistant than binary fluoroelastomer. The physical properties of binary fluoroelastomer after 100 hours of hot aging of air at 300 °C × 100 hours are comparable to the properties of the ternary type after 300 °C × 100 hours of hot air aging, and its ripping elongation can be maintained at about 100% and the hardness is 90 to 95 degrees. Fluoroelastomer ternary glue maintains good elasticity after 16 hours of hot air aging at 350 °C, maintains good elasticity after 110 minutes of hot air aging at 400 °C, and maintains good elasticity after 110 minutes of hot air aging at 400 °C, the elongation of rubber containing spray carbon black, hot crack carbon black or carbon fiber rises by about 1/2 to 1/3, and the strength drops by about 1/2, still maintaining good elasticity.
Aging resistance
Fluoroelastomer has excellent weather aging resistance and ozone resistance. It has been reported that the VitonA developed by DuPont is still performing satisfactorily after ten years of natural storage, with no significant cracking after 45 days in air with an ozone concentration of 0.01%. Type 23 fluoroelastomer has excellent weather aging resistance and ozone resistance.
Vacuum performance
Binary fluoroelastomers have excellent vacuum properties. The vacuum degassing rate of vulcanized rubber in the basic formulation of ternary fluoroelastomer is only 37× 10-6 inches per second. Cm 2. Ternary fluoroelastomers have been successfully applied under vacuum conditions of 10-9 inches.
Mechanical properties
Fluoroelastomer has excellent physical and mechanical properties. The strength of binary fluoroelastomer is generally between 10 and 20MPa, the elongation of tearing is between 150 and 350%, and the tear strength is between 3 and 4KN/m. In general, the compression set deformation of the fluoroelastomer at high temperature is large, but if compared with the same conditions, such as from the compression set of the same time at 150 ° C, butyl and neoprene rubber are larger than the 26-type fluorine glue, and the compression deformation of binary fluoroelastomer at 200 ° C × 24 hours is equivalent to the compression deformation of butadiene rubber at 150 ° C × 24 hours.
Electrical properties
Low breathability
The solubility of fluoroelastomers to gases is relatively large, but the diffusion rate is relatively small, so the overall performance of breathability is also small. It is reported that the permeability of type 26 fluoroelastomer for oxygen, nitrogen, helium and carbon dioxide gas at 30 °C is comparable to that of butyl rubber and butadiene rubber, which is better than neoprene and natural rubber.
Low temperature performance
The low temperature performance of fluoroelastomer is not good, which is due to its own chemical structure. The low temperature performance of the actual fluoroelastomer used is usually expressed in terms of brittleness temperature and compression cold tolerance coefficient. The formula of the rubber compound and the shape of the product (such as thickness) have a relatively large impact on the brittleness temperature, such as the increase in the amount of filler in the formula, the brittle temperature sensitively deteriorates, the thickness of the product increases, and the brittleness mixture is also sensitively deteriorated.
Radiation resistance
The radiation resistance of fluoroelastomer is a kind of elastomer, binary rubber radiation after the performance of crosslinking effect, ternary fluoroelastomer in the air at room temperature radiation at 5×107 lun under the dose of the performance of drastic changes, in 1 × 107 lun under the condition of hardness increased by 1 to 3 degrees, strength decreased by 20% or less, elongation decreased by 30% to 50%, so it is generally believed that type 246 fluoroelastomer can withstand 1 × 107 lun, the limit is 5×107 lun.
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Focus on applications
Because of its high temperature resistance, oil resistance, high vacuum resistance and acid and alkali resistance, and resistance to a variety of chemicals, fluoroelastomer has been applied to modern aviation, missiles, rockets, astronautics, ships, atomic energy and other cutting-edge technologies and automotive, shipbuilding, chemical, petroleum, telecommunications, instruments, machinery and other industrial fields.
Typical applications
Fluoroelastomer seals, when used for engine sealing, can work for a long time at 200 ° C ~ 250 ° C, short-term work at 300 ° C, and its working life can be the same as the engine rework life, up to 1000 ~ 5000 flight hours (time 5 to 10 years); when used in the chemical industry, inorganic acids (such as 67% sulfuric acid at 140 ° C, concentrated hydrochloric acid at 70 ° C, 30% nitric acid), organic solvents (such as chlorinated hydrocarbons, benzene, high aromatic gasoline) and other organic matter (such as butadiene, styrene, Propylene, phenol, fatty acids at 275 °C, etc.; for deep well oil production, it can withstand the harsh working conditions of 149 °C and 420 atmospheres; when used for superheated steam seals, it can work in the steam medium and long term of 160 ~ 170 °C. In the production of monocrystalline silicon, fluoroelastomer seals are commonly used to seal special media at high temperatures (300 °C) - trichlorosilane, silicon tetrachloride, gallium arsenide, phosphorus trichloride, trichloroethylene and 120 °C hydrochloric acid.
In terms of high vacuum applications, when the flight altitude is 200 ~ 300Km, the air pressure is 133× 10-6 Pa (10-6mmHg), neoprene, butyl rubber can be applied; when the flight altitude exceeds 643Km, the air pressure will drop to 133× 10-7 Pa (10-7mmHg) or less, in this high vacuum only fluoroelastomer can be applied. Generally, before the use of high vacuum or ultra-high vacuum device system, it needs to undergo high temperature baking treatment, binary and ternary fluoroelastomers can withstand high temperature aging of 200 °C ~ 250 °C, so it has become the most important rubber material in high vacuum equipment and spacecraft.
Hoses made of fluoroelastomer are suitable for high temperature resistance, oil resistance and special media resistance, such as as aircraft fuel oil, hydraulic oil, synthetic diester oil, high temperature hot air, hot inorganic and other special media (such as chlorinated hydrocarbons and other chlorides) transportation, guidance, etc. Wires and cables made of fluoroelastomer have good flexibility and good insulation. Glass fiber adhesive cloth made of fluoroelastomer can withstand high temperatures and chemical corrosion at 300 °C. After the aramid cloth is coated with fluorine glue, it can make a high-temperature, acid-resistant and alkali-resistant storage tank connection telescopic pipe between the petrochemical plant (there can be metal flange connection at both ends), which can withstand high pressure, high temperature and medium corrosion, and cushion the deformation and expansion of the two tanks. The adhesive cloth sealing bag made of nylon cloth after coating with fluorine glue serves as a soft seal for the inner floating roof storage tank of the refinery, which plays a role in sealing and reducing the volatile loss of the oil liquid level.
Type 23, four-propylene type fluoroelastomer is mainly used as acid-resistant, resistant to special chemicals corrosive sealing occasions. Hydroxynitrosoelastomer is mainly used as protective products and sealing products, in the form of solution as a non-combustible coating, used in fireproof electronic components and pure oxygen working parts. Its solution and liquid rubber can be sprayed, poured and other methods to manufacture many products, such as cosmos suits, gloves, pipe straps, balls and so on. It can also be used as an adhesive for glass and metal "sequestrations" and fabrics, gaskets for the manufacture of sponges and contact rocket propellants (N2O4), "O" rings, capsules, valve seals, etc.
The seals made of G series fluoroelastomer have the performance of high temperature vapor resistance, methanol gasoline or gasoline containing high aromatic hydrocarbons that cannot be achieved by using VitonA, B, E and other fluoroelastomers; GLT type fluoroelastomers, phosphorus chloride rubbers, perfluoroelastomers, etc. have a wide range of temperature ranges, low temperature flexibility, elastic sealing, etc. Perfluoroelastomer also has outstanding resistance to media corrosion and is widely used in cutting-edge military technology.
Putty, a sealant made of fluoroelastomer, has outstanding fuel oil resistance and can be used in oils around 200 ° C, and is used as a sealing material for the overall fuel tank of the aircraft. Closed-cell sponge made of fluoroelastomer, with acid resistance, oil resistance, wide use temperature range and good insulation, can be used as rocket fuel, solvent, hydraulic oil, lubricating oil and ointment sealing and rocket, missile shock absorbing material, temperature resistance up to 204 °C, impregnated with fluorine glue emulsion asbestos fiber cloth, can be made into asbestos rubber board, for high temperature resistance, combustion resistance and chemical corrosion resistance occasions.
Automotive industry
With the rapid development of the automotive industry, the increase in the temperature of the automobile engine compartment, the increasing use of modified fuels and highly corrosive engine fuels, fluoroelastomer is more widely used in the sealing materials of automobiles than ever before.
In order to increase the power of the car engine, save fuel, and ensure the safety of the car, a new fuel injection system has emerged. In this system, the car flows from the tank into the engine and then back into the tank cycle, where gasoline mixed with oxygen produces hydrogen peroxide. Gasoline containing hydroperoxides is called "acid gasoline", which can soften or harden a variety of hydrocarbon rubber. Fluoroelastomers, on the other hand, do not deteriorate due to contact with acidic gasoline.
New environmental protection regulations are enacted every year in countries around the world. The total hydrocarbon emissions of automobiles are increasingly restricted, and it is becoming increasingly difficult for the automotive industry to meet this requirement. In the United States, cars must pass the SHED (Sealed Box Evaporation Determination) test. Fluoroelastomer has excellent barrier to hydrocarbon permeation (Table 1), and the fuel hose structure is covered with a fluoroelastomer layer to reduce the permeability of hydrocarbons.
The products of the automotive fuel system must function normally in the temperature range of -40 °C ~ 150 °C. However, the low temperature resistance of fluoroelastomer deteriorates with the increase of fluorine content (the glass transition temperature rises), and in order to manufacture products with normal performance at -40 ° C, it is necessary to improve the fluoroelastomer products with poor cold resistance. Nowadays, perfluoroelastomers have been developed and listed, which effectively improves the low temperature performance of fluoroelastomers, but it is difficult to promote them in large quantities due to price problems.
The automotive industry pays close attention to methanolization of fuels and is eagerly conducting research on FFVs (Flexible Fuel Vehicles) that may adapt to any fuel, and the FFV of rubber parts is particularly urgent. When methanol is mixed with gasoline, the volume of fluoroelastomer is about 10% larger. However, in the case of methanol alone, the volume of fluoroelastomers varies greatly due to the different fluorine content. When the fluorine content is high, almost no swelling occurs, but as the fluorine content decreases, the swelling becomes larger in the low temperature area, especially in the case of 66% fluorine content, the volume swelling will increase significantly. This can be thought to be due to the proximity of the methanol conjugate produced by the hydrogen bond at low temperatures to the SP value of the polymer with a fluorine content of 66%.
In a sense, fluoroelastomers are also the products of growth with the progress and development of the times. Although the price of these materials is high, but with their excellent wear resistance, oil resistance and reliability, etc., has a high practical value, therefore, its dosage is gradually rising is not surprising. There is still great potential and possibility for the development of fluoride, and it is expected that fluoropolymers with higher use value will be developed in the future.
Perfluoroelastomer