Types and applications of silicone rubber sealing products
Silicone rubber sealing products a wide variety of different working conditions, such as heat, oil resistance, chemical corrosion resistance and working state (static, dynamic, rotation and swing, etc.), speed, working pressure, etc.. So for the mechanical seal of the rubber seal, rubber from the first to consider the use of conditions or special conditions, then the vulcanizing system, reinforcing filling system and softening system, protection system comprehensive consider the reasonable formulation and processing technology.
Generally used for the mechanical seal of the rubber material, to have a good flexibility and lower compression permanent deformation, to meet the special requirements of the use of different products. As a dynamic seal, it also requires that the rubber material has a certain tensile strength, good wear resistance, tear resistance.
1, O type sealing ring
O type of sealing ring is a simple structure, a wide range of specifications, a large number of a large number of sealing products. The sealing quality life of O type sealing ring depends on the size precision and the rubber material. General requirements of the plastic material with a certain mechanical strength, tear resistance and good heat resistance, oil resistance, chemical resistance, and in the use of the conditions to have a smaller compression permanent deformation, is its main indicators. According to the requirement, generally have a heat and oil resistant rubber, nitrile rubber to use up. High temperature requirements (e.g., L90 - 150~C degrees C) oil resistant seal products can be used with acrylic rubber. High temperature oil resistant rubber products with fluorine rubber, heat resistant silicone rubber. When the working pressure is high, the method of increasing the hardness of the O type rubber material is to increase the filling amount of the carbon black, but the filling amount is too high, the difficulty of mixing, and the basic properties of the vulcanized rubber are damaged, and the rubber material is easy to be burnt. In the use of the same kind of rubber, such as nitrile rubber, in order to improve the heat resistance and oil resistance, reduce compression permanent deformation, the peroxide (DCP) curing system or effective sulfur curing system (low sulfur and high accelerator). These two kinds of curing system can generate more carbon one carbon bond cross link structure and one sulfur bond crosslinking structure, which can effectively improve the heat resistance and oil resistance of the cured rubber, and reduce the compression permanent deformation.
O type sealing ring of heat-resistant, resistant oil compound filling reinforcing system, the use of lower activity of thermal cracking carbon black, spray carbon black or semi reinforcing carbon black, the characteristics of the carbon black is coarse particles, plastic material with good elasticity, low heat, compression permanent deformation low and a lot of filling, reduce sizing cost. Such as the O type sealing ring used in the dynamic seal conditions, the need to increase the tear resistance, can be used with a high part of the activity of high wear resistant carbon black. Fluorine rubber is a kind of self reinforcing rubber, such as filled with active carbon black to reduce the mechanical properties, so it is generally filled with a small amount of active coarse particles of carbon black or spray carbon black.
2, oil seal ring
Oil seal is an important part of the transmission shaft seal, its quality and life directly related to the normal operation of the machine. Oil seals are generally used in dynamic conditions, and with the sealed medium such as oil direct contact, so the oil seal must have a good oil resistance, wear resistance and a smaller coefficient of friction. Due to friction heat seal and the shaft is very high, especially the lip is higher, so the rubber heat aging resistance. In addition, the rubber material flow performance is good, and it is easy to move and fill the mold cavity when the mold is closed. The main performance index of the oil seal is heat resistance, oil resistance, commonly used rubber with nitrile rubber (long-term use temperature 120~C) and acrylic rubber (120~C 170 DEG C), fluorine rubber (a 220oc 170 DEG C). Oil seal in normal use, late leakage failure, mainly oil seal lip mouth of age hardening, lose their elasticity and cracks caused by. In order to improve the service life of oil seal, the heat resistance of rubber compound used in oil seal must be improved. Glue is determined and curing system is the key, such as nitrile rubber, choose peroxide DCP vulcanization system and fill with improved heat resistance of the co curing agent (such as magnesium methacrylate) can effectively improve the heat resistance. To fill up the system concerned, due to the oil seal requires certain mechanical strength and tear resistance, good wear resistance, are often used in high abrasion furnace black, fast extruding carbon black, and general purpose black and semi reinforcing carbon black, pyrolysis carbon black, spray carbon black and used. White carbon black is often used in filling reinforcing agent, such as a single white carbon black, in order to improve the mechanical strength of the silane coupling agent can be added. Another advantage of silica compound and metal material is good adhesion. For fluorine rubber compound, not suitable for the use of fine particle activated carbon black, usually used for the thermal cracking of carbon black particles or spray carbon black. In order to increase oil seals of vulcanized rubber self lubrication and reduce friction coefficient, often adding graphite powder, molybdenum disulfide, and other filling materials.
3, rubber sealing strip
Rubber sealing strip is mainly used in the automotive, aircraft, railway and high-rise buildings of various doors and windows, to prevent the outside dust, air, water and other parts of the system into a rubber. Rubber sealing strip as most for cars, trains, planes, and high-rise building doors and windows, so the requirements of rubber material has good weather resistance, aging resistance and better mechanical properties and proper elongation, compression permanent deformation and cold resistance. The processing properties of the compound, liquidity, extruding performance is better, dimension stability, surface smooth, the surface can not have impurities, scarring. Rubber seal rubber ethylene propylene rubber to three yuan for the best, the main material is used, it is characterized by good weatherability. Rubber sealing a compound recipe reinforcing filling system used by extrusion performance, small deformation and smooth surface of carbon black varieties, such as fast extruding CB (N550), or with general motors, half fill strong carbon black, spray carbon black. For cars and other high-end sealing products, using carbon black is not only to meet the physical and mechanical properties, processing properties and surface must be smooth and free of particles, so the requirements of carbon black residue on sieve was lower, must not have impurities, and the degree of purity of the carbon black.
In this paper, from Shenzhen City, Qi Yu Silicone Rubber Co., Ltd.: http://www.szhcty.com/news_v.asp? Id=634
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