Sealing material of solenoid valve

NBR (NR butadiene rubber)

Obtained from emulsion polymerization of butadiene and acrylonitrile, acrylonitrile butadiene rubber is mainly produced by low temperature emulsion polymerization. It has excellent oil resistance, high wear resistance, good heat resistance and strong adhesion.

Its disadvantages are low temperature resistance, poor ozone resistance, poor electrical performance and low elasticity.

In addition, it also has good water resistance, air tightness and excellent bonding performance. It is widely used in the manufacture of various oil-resistant rubber products, various oil-resistant washers, gaskets, casings, flexible packaging, flexible rubber tubes, printing and dyeing rubber rollers, cable rubber materials, etc. it has become an essential elastic material in the automotive, aviation, petroleum, copying and other industries.

NBR has excellent oil resistance, which is second only to polysulfide rubber and fluororubber, and has wear resistance and air tightness. The disadvantage of NBR is that it is not resistant to ozone and aromatic, halogenated hydrocarbon, ketone and ester solvents, so it is not suitable for insulating materials.

• Main purpose:

NBR is mainly used to make oil resistant products, such as oil pipes, tapes, rubber diaphragms and large oil bags. It is commonly used to make various oil resistant molded products, such as O-rings, oil seals, cups, diaphragms, valves, bellows, etc., and also used to make rubber plates and wear-resistant parts.

EPDM ethylene propylene diene monomer

EPDM is a terpolymer of ethylene, propylene and non conjugated diene. It began commercial production in 1963. The annual consumption of the world is 800000 tons. The most important characteristic of EPDM is its superior ability to resist oxidation, ozone and erosion.

Because EPDM belongs to polyolefin family, it has excellent vulcanization properties. EPDM has the lowest specific gravity of all rubbers. It can absorb a large number of fillers and oil, but has little effect on its properties. Therefore, the rubber compound with low cost can be made.

• Molecular structure and properties:

EPDM is a terpolymer of ethylene, propylene and non conjugated diene. Diene has a special structure, only one of the two bonds can be copolymerized, the unsaturated double bond is mainly used as the cross chain. The other unsaturated one will not be the main chain of polymer, but the side chain. The main polymer chain of EPDM is completely saturated. This property makes EPDM resistant to heat, light, oxygen, especially ozone. EPDM is essentially nonpolar, resistant to polar solutions and chemicals, with low water absorption and good insulation properties.

• Characteristic:

1. Low density and high filling property; 2. Aging resistance; 3. Corrosion resistance; 4. Water vapor resistance; 5. Hot water resistance; 6. Electrical performance; 7. Elasticity and adhesion

There are various types of fluorine containing rubbers according to fluorine content, i.e. monomer structure. At present, the fluorine rubber widely used in hexafluoride system was first listed by DuPont company under the trade name of "Viton". Its high temperature resistance is better than that of silicone rubber? Chemical resistance, resistance to most oils and solvents (except ketones and esters), weather resistance and ozone resistance are good, but its cold resistance is poor. It is widely used in automobile and other products, The temperature range of the seal in the chemical plant is - 20 ℃ ~ 260 ℃. The low temperature resistant type can be used to - 40 ℃, but the price is high.

Viton fluororubber (FKM)

There are various types of rubber containing fluorine according to fluorine content or monomer structure. At present, the widely used fluororubber of hexafluoride series was first listed by DuPont company under the trade name of "Viton". Its high temperature resistance is better than that of silicone rubber. Chemical resistance, resistance to most oils and solvents (except ketones and esters), good weather resistance and ozone resistance, but poor cold resistance; generally widely used in steam turbine cars, B and other products, chemical plant seals, use temperature range - 20 ℃ ~ 260 ℃, low temperature resistant type can be used to - 40 ℃, but the price is high.