1, metallurgy, automotive industry and oilfield drilling requirements for rubber seals
(1) metallurgical machinery: metallurgical industry, high-speed wire rod mill, small mill technology is developing rapidly, mainly high rolling speed, productivity has increased dramatically, the most advanced foreign up to 120m / s, the mill oil film bearing speed continues to increase, the bearing with the seal requirements continue to improve. Seal form for double-sided seal (also known as roll diameter seal), there are two sealing surface, one side of the sealing water vapor, the other side of the sealing lubricating oil, the working temperature is generally higher than 120 ℃, the shape and structure of the complexity of the size requirements. Product requirements rubber compound with good heat resistance, aging resistance, water vapor and lubricant resistance, with good process performance, good mobility, conducive to the manufacture of complex structural products.
(2) automotive industry: the automotive industry and related fields has been the largest user of (rubber) seals. In recent years, faced with a variety of higher user requirements, the intensification of competition, coupled with the strengthening of environmental regulations worldwide, prompting manufacturers to continue to improve, optimize the design, improve performance, reduce emissions, reduce weight to reduce fuel consumption. With technological progress, high-tech, high-performance equipment and devices continue to develop and popularize, such as: new aerodynamic design of high-performance engines (such as turbocharged engine systems), turbochargers, automatic transmissions, to improve fuel economy, electronic fuel injection devices, as well as new technologies, such as exhaust gas purification devices. Make the car weight, specification is getting smaller and smaller, the engine room space is getting narrower and narrower, the temperature is getting higher and higher; the use of the latest level of engine oil (SF), as well as lubricants and other oil improvements, additives, especially corrosive additives more and more, more and more complex chemical environments, and at the same time, automotive rear crankshaft inversion of crankshafts with silicone seals with the increasingly serious damage phenomenon, and therefore the rubber seals of heat resistance, Corrosion resistance, resistance to lubricating oil additives and oxidized oil (acid oil) performance, and life and so on put forward higher requirements, the traditional NBR although the price is low, good overall performance, widely used as oil-resistant rubber, but due to the existence of double bonds in the chain link, heat aging, weather resistance, chemical stability is poor, can not meet the actual requirements, must be used with a special combination of performance of the special rubber materials, such as ACM, FKM and HNBR.
(3) oilfield: for rubber seals, oil drilling in the oil wells downhole seal has always been the most difficult, the most demanding environment, and underground crude oil due to many years of mining, in recent years has begun to gradually transfer from the land plains to the deep sea or desert areas, resulting in further deepening of the depth of the oil wells, to the deep wells, the development of ultra-deep wells, the downhole seals must be resistant to more demanding and complex working conditions such as high and low temperatures, high pressure, the current The bottom of the well temperature and pressure has generally reached 200 ℃ and 100 MPa. High sulfur oil, H2S, H20, C02-containing strong corrosive media and most of the equipment is exposed to the drilling fluid containing anticorrosive agents, various types of additives, the performance of the rubber sealing materials used than the usual much higher, the current use of large quantities of fluoroelastomers; wells downstream working conditions have a changeable environment, there may often be Unpredictable situations, such as the danger of sudden pressure drop, the working pressure of the well is high, all elastomer seals have this danger, the elastomer is very easy to appear bubbles, the rubber products are exposed to soluble high-pressure gas for a period of time, such as the sudden loss of pressure, soluble gases will be rapidly expanded in the body, the formation of large bubbles, the explosion, these unpredictable situations will lead to the replacement of seals to make the well stop running, the loss of daily production can be up to thousands of tons of oil. These unforeseen circumstances can lead to well shutdowns to replace seals, resulting in millions of dollars in lost production per day. This requires the search for high strength, good recovery and better adapted rubber materials to improve sealing performance.
2、Characteristics of FKM
Fluoroelastomer was initially introduced to meet the needs of the aviation industry for high-performance sealing elastomers, and then quickly expanded to other areas such as automotive, chemical and other fields, currently the main use of foreign fluorine rubber in the automotive industry, and its excellent practical performance in high temperature, strong corrosive environments and well-known.
Fluorine rubber has the following characteristics.
(1) excellent heat resistance, the best rubber for high temperature performance, can be used for a long time at 230 ℃, short-term use of up to 300 ℃, while the general oil-resistant nitrile rubber use temperature does not exceed 120 ℃, ACM 160 ℃, chlorine ether for the following 120 ℃.
(2)Excellent oil resistance, the best among all rubbers, can resist most mineral oil and lubricating oil.
(3)Excellent resistance to chemical media, of which solvent resistance, fuel resistance, acid and alkali resistance, vapor resistance are the best among all rubbers, resistant to most mineral acids.
(4) Excellent flame resistance, self-extinguishing flame retardant rubber;
(5) Excellent weather resistance, mold and mildew resistance for the best ozone-resistant rubber.
(6) excellent high-temperature strength performance and compression permanent deformation performance, high-temperature physical and mechanical properties superior to most other elastomers; in addition to low-temperature performance is more general, many of the properties of fluoroelastomer in rubber are the most excellent, or ranked among them, especially its resistance to oils and chemicals, resistant to degradation of more than three hundred kinds of fluids, and even more rare is the resistance to resistance to the effects of temperature rise is not great; fluoroelastomer low-temperature performance is general, but Even if the static sealing effect used in conditions close to absolute zero is also satisfactory, fluoroelastomer has most of the other rubber does not have excellent performance, almost indispensable sealing material in high temperature and strong corrosive environments, has been in the ever-changing automotive, chemical, office automation and semiconductor manufacturing and other industries play an indispensable and important role!
3、Application status of FKM in three industries
Automobile, metallurgy and oil field industry increasingly harsh working conditions for rubber and plastic sealing materials for high temperature resistance, oil resistance, chemical resistance and the complex environment of the physical and mechanical properties of higher requirements, the traditional nitrile rubber can not meet the needs of the need must be used with a special combination of fluorine rubber rubber and other types of rubber. Fluoroelastomer with its excellent performance has been widely used in these industries.FKM has been widely used in these industries with its excellent performance.
The use of FKM is increasing worldwide, and most of them are used in the automotive industry. Such as the current world production of fluoroelastomer has exceeded 8000t, of which 60 a 70% with automotive products, mainly the manufacture of various types of oil seals (rotary, reciprocating), including engine oil seals, transmission oil seals (such as: crankshaft before and after the oil seals, gear compartment oil seals, camshafts, hubs and half-shafts oil seals, valve guides oil seals, etc.), 'as well as transmission seals, air intake gasket compressor O-ring, fuel system seals (e.g., fuel injection unit seals, fuel pump diaphragms, pump seals, injector 0-ring, accelerator pump bowl, filter seals, carburetor seals and gasoline pump seals).
Improvement of automobile engine performance, the use of new grade engine oil (such as SF) and lubricant improvement, corrosive additives more and more, making the engine temperature is getting higher and higher, the use of oil seals can be as high as 30m/s, the use of the temperature is generally up to 150 ℃; chemical environment is getting more and more harsh, while the automobile after the crankshaft of the inverted crankshaft with silicone seals with the damage phenomenon is getting more and more serious, the use of fluoroelastomer seals can be The use of Viton seals can improve oil resistance, heat resistance, extend service life (up to 50~600/0), reduce wear 40~60%.
Metallurgical industry, metallurgical high-line rolling mill shaft diameter double-sided sealing foreign countries generally use NBR, the biggest drawback is that the product is easy to aging, wear and tear, low life expectancy, generally 3. 5 weeks, continuous casting machine is the key equipment for metallurgical enterprises, the fan cylinder seals are fluorine rubber material.
Oil drilling oil well seals face the most difficult and harsh working conditions environment, due to drilling to deep wells, ultra-deep well development, oil wells downhole seals must face more complex and harsh working conditions environment (high and low temperatures, high pressure, high sulfur petroleum, strong corrosive media containing H2S, H20, C02, as well as most of the equipment is exposed to anticorrosive agents, various types of additives drilling fluid). Previously, the rubber seals used on the oil extraction equipment are mostly based on nitrile rubber with good oil resistance, and have been gradually developed into fluorine rubber, silicone rubber and HNBR rubber, etc., and sometimes even require the use of tetra-propyl fluorine rubber, perfluoroethers rubber and other special fluorine rubber, such as in contact with sulfur-containing crude oil in the downhole and wellhead equipment, such as blowout preventer, downhole safety valves and packers in the rubber seals have been widely used in the use of fluorine rubber. For example, fluorine rubber has been commonly used in rubber seals for downhole and wellhead equipment in contact with sulfur-containing crude oil, such as blowout preventer and packer.
