Nitrile rubber
Nitrile-butadiene rubber (NBR) is a copolymer of acrylonitrile and butadiene monomers. It is mainly produced by low-temperature emulsion polymerization. It has excellent oil resistance, high wear resistance, good heat resistance and viscosity Relay is strong. The disadvantages are poor low temperature resistance, poor ozone resistance, poor insulation performance and slightly lower elasticity.
Nitrile rubber is mainly used in the manufacture of oil-resistant rubber products. There are five kinds of acrylonitrile content (%) in nitrile rubber, such as 42-46, 36-41, 31-35, 25-30, 18-24. The higher the acrylonitrile content, the better the oil resistance, but the corresponding decrease in the cold resistance. It can be used in air at 120℃ or in oil at 150℃ for a long time. In addition, it also has good water resistance, air tightness and excellent bonding properties. It is widely used to make various oil-resistant rubber products, various oil-resistant gaskets, gaskets, casings, flexible packaging, soft rubber hoses, printing and dyeing rubber rollers, cable rubber materials, etc. It has become indispensable in the automotive, aviation, petroleum, photocopying and other industries elastic material
NBR general performance
Nitrile rubber has better heat resistance, and its heat resistance is better than that of natural rubber and styrene-butadiene rubber. The long-term use temperature can reach 100 degrees Celsius, and it can be used for 40 days at 120 degrees Celsius.
1.Ozone resistance is worse than CR and better than NR.
2. Endow the rubber with better physical and mechanical properties and wear resistance through reinforcement.
3. When the acrylonitrile content of nitrile rubber is 39%, the air tightness is equivalent to that of IIR rubber, and the air tightness is better.
4.Low temperature flexibility is general.
5.Excellent antistatic performance.
6. The use of polar lipids has better plasticizing effect.
7.Good compatibility with polar substances, such as PVC, alkyd resin, nylon.
8. The self-viscosity is low, and the heat generated during the mixing process is large.
The properties of NBR
NBR has excellent oil resistance. In a typical NBR structure, trans accounts for about 78%. Due to the cyano group contained in the NBR molecular chain structure, oil resistance (such as resistance to mineral oils, liquid fuels, animal and vegetable oils and solvents) is superior to natural rubber, neoprene and styrene-butadiene rubber. Compared with other rubbers, NBR has a wider range of use temperature, its long-term use temperature is 120 ℃, and NBR has good low temperature resistance, and the minimum glass transition temperature can reach -55 ℃.
NBR has good chemical resistance and good processing performance. With the increase of acrylonitrile content in its structure, its relative density increases, the vulcanization speed increases, and the tensile strength performance improves, but the resilience performance decreases and the cold resistance becomes poor. Because the cyano group in NBR is easy to be polarized by electric field, the dielectric properties are reduced, and it is a semiconductor rubber. NBR can be divided into 5 categories according to the level of ACN content: ultra-high, high, medium-high, medium and low acrylonitrile. Production methods are divided into continuous and batch polymerization methods. The continuous polymerization method is usually used for low-variety and high-volume production with low consumption. The batch polymerization method is suitable for multi-variety and small batch production, and the engineering construction consumption is high.
Although nitrile rubber has excellent physical and mechanical properties and processing properties, its long-term performance in acidic gasoline and high temperature (150 ℃) environments is inferior to fluororubber and acrylate rubber. For this reason, hydrogenated nitrile rubber with excellent performance has been developed ( HNBR). In addition, it has also developed ultra-high cold resistance and high-purity nitrile rubber and carboxylated nitrile rubber (XNBR), etc.
Excellent oil resistance of nitrile rubber
Nitrile rubber is one of the most representative rubbers with excellent comprehensive properties such as oil resistance, physical and mechanical properties, and chemical resistance. Effective use of these properties can make it suitable for various applications. Among general-purpose rubbers, NBR rubber has far better resistance to benzene, petroleum-based oils and non-polar solvents than non-polar rubbers such as NR, SBR, and IIR, and is also better than polar CR. Solvent and polar oil resistance is not good enough
Temperature resistance range of silicone
Ordinary Silicone can withstand high temperatures between 200 and 300 degrees Celsius. In a short period of time, such as within two hours, the highest temperature can reach about 350 degrees Celsius, which is often used for Silicone with special performance requirements.
Silicone is suitable for drying, moisture-proof and rust-proof. It can prevent instruments, meters, weapons and ammunition, electrical equipment, medicines, food, textiles and other packaging items from getting wet, and can also be used as catalyst carrier and dehydration and purification of organic compounds. Because of its high bulk density and obvious hygroscopic effect under low humidity, it can be used as an air purifier to control air humidity.
It is also widely used in the shipping process, because the goods are often affected by moisture and deteriorate due to high humidity during transportation. This product can be used to prevent moisture and ensure the quality of the goods. Fine-pored Silicone is also commonly used for dehumidification between two layers of parallel sealed window panels, which can maintain the transparency of the two layers of glass.
The main application of NBR
Because of its excellent oil resistance and physical and mechanical properties, NBR is widely used in the manufacture of various oil-resistant rubber products, such as O-rings, gaskets, hoses, and fuel tank linings, printing cylinders, oil tank linings, insulating floor plates, oil-resistant Soles, hard rubber parts, fabric coatings, pipe thread protection, pump impellers and wire wraps, adhesives, films for food packaging, rubber gloves, etc. In 2014, there were more than 30 countries producing NBR in the world. The largest consumption area was the production of oil-resistant rubber hose products and flame-retardant conveyor belts, and the consumption accounted for about 53% of the total consumption of NBR. Using nylon interlayer and chlorobutyl rubber as the inner and outer layers, it can produce a new type of hose that can prevent the leakage of Freon gas. The car is made with HNBR as the inner layer, nylon 66 as the reinforcement layer, and CSM as the outreach. Power steering is good, and it can withstand 4 million pulses at 12°C. In addition, nitrile rubber is also an ideal material for automotive Asahi CVT tape, automobile and aircraft fuel. my country's nitrile rubber is mainly used in the military, automobile, and aviation industries, mainly oil-resistant parts such as fuel tanks, and also used in seals, transmission belts, hoses, and plastic modified materials. The dosage is increasing year by year. Almost all existing hose factories and sundry factories use NBR to a greater or lesser extent. The second largest application field of nitrile rubber is sealing rubber products, which are widely used in aerospace devices, transformers, liquefied petroleum gas pipelines, etc. Among them, automotive seals account for about 50% of the total consumption of sealant rubber products. The nitrile rubber used for wire and cable products in my country is about 1000t every year. Using dynamic vulcanization technology and compatibilization technology, new alloy materials such as NBR/PP, NBR/PS, NBR/PVC > NBR/PA, NBR/ACR, NBR/CSM, NBR/EPDM, NBR/BR can be prepared. market prospects. NBR is also used in the manufacture of oil-resistant rubber sheets, printing rubber rollers, coal mine flame-retardant hydraulic hoses, oil tanks, fuel tanks, oil containers, oil-resistant rubber shoes, etc. [1]
Abroad, it is mainly used in aviation, automobile, printing, textile and machinery manufacturing. Due to the development of NBR modified varieties, the application prospect of nitrile rubber has been expanded. To sum up, it mainly includes: manufacturing fuel oil pipes, grease cloth, oil seals, oil filling pipes, oil-resistant rubber parts and various products in contact with oil. Nitrile rubber has good compatibility with PVC, acetate resin, etc., so it is often blended with resin to modify the material. PVC is often used to improve processability and impact resistance, phenolic resin is used to obtain flexible materials, and fluid materials are produced after asphalt mixing.
Nitrile rubber is mainly used to make oil-resistant products, such as oil-resistant pipes, tapes, rubber films and large oil bladders, etc. It is often used to make various oil-resistant molded products, such as O-rings, oil seals, leather cups, diaphragms, valves, bellows , hoses, seals, foam, etc., also used to make rubber sheets and wear-resistant parts
The development of NBR
Due to its excellent oil resistance, heat resistance and physical and mechanical properties, nitrile rubber has become the standard elastomer for oil-resistant rubber products, and is widely used in automotive, aerospace, oil exploration, petrochemical, textile, wire and cable, printing and food packaging and other fields. At present, the domestic production is insufficient, and the annual import volume is about 40,000 tons. In 2001, the global total annual production capacity of nitrile rubber was about 650,000 tons, distributed in 17 countries and regions. Among them, the annual production capacity of China's surrounding areas is about 270,000 tons, accounting for 40% of the world's total annual production capacity. Except for India, China is the main source of imports.
The largest use of nitrile rubber is the production of oil-resistant hoses and flame-retardant conveyor belts, and its consumption accounts for about 50% of the total consumption; followed by sealing products, about half of which are automotive sealing products; in wire and cable, adhesives, printing and luggage Products and other aspects also have applications. In addition, the blending and modification of nitrile rubber and other materials has become a research hotspot. Using dynamic vulcanization technology and other technologies, it is possible to prepare nitrile rubber/polyvinyl chloride, nitrile rubber/polypropylene, nitrile rubber/ethylene propylene rubber, nitrile rubber/polystyrene, nitrile rubber/chlorosulfonated polyethylene, Nitrile rubber/polyamide, nitrile rubber/butyl rubber and other blended products, of which nitrile rubber/polyvinyl chloride blend is the most widely used, mainly used in the wire and cable industry. With the rapid development of the communication industry, it has strong competitiveness in the field of ethylene propylene rubber/polypropylene in the field of submarine cables. At present, there are nearly 10,000 wire and cable enterprises in China, and the annual consumption of nitrile rubber/polyvinyl chloride is very large. In addition, the blended adhesive can also be used in the outer layer adhesive of oil pipes and fuel pipes, automotive waterproof seals and molded parts, foam insulation layers, rubber rings, protective coatings, etc.
