Nitrile rubber (NBR) is a copolymer of acrylonitrile and butadiene monomer. It is mainly produced by low temperature emulsion polymerization. It has excellent oil resistance, high wear resistance, good heat resistance and strong adhesion.
Nitrile rubber is mainly used to manufacture oil resistant rubber products. Acrylonitrile content (%) in nitrile rubber includes 42 ~ 46, 36 ~ 41, 31 ~ 35, 25 ~ 30 and 18 ~ 24. The higher the content of acrylonitrile, the better the oil resistance, but the cold resistance decreases accordingly. It can be used in air at 120 ℃ or oil at 150 ℃ for a long time. In addition, it also has good water resistance, air tightness and excellent bonding performance. It is widely used to make various oil resistant rubber products, a variety of oil resistant gaskets, gaskets, sleeves, flexible packaging, flexible hose, printing and dyeing rubber rollers, cable rubber materials, etc. it has become an essential elastic material in automobile, aviation, petroleum, copying and other industries.
NBR has excellent oil resistance. Trans accounts for about 78% of the typical NBR structure. Because the molecular chain structure of NBR contains cyano group, the oil resistance (such as resistance to mineral oil, liquid fuel, animal and vegetable oil and solvent) is better than natural rubber, neoprene and styrene butadiene rubber. Compared with other rubbers, NBR has a wider range of service temperature. Its long-term service temperature is 120 ℃. At the same time, NBR has good low temperature resistance, and the minimum glass transition temperature can reach - 55 ℃.
NBR has good chemical stability and processing performance. With the content of acrylonitrile in its structure, its relative density increases, the vulcanization speed increases, and the tensile strength improves, but the resilience decreases, and the cold resistance becomes worse. Because the cyano group in NBR is easy to be polarized by electric field, its dielectric properties are reduced. It is a semiconductor rubber. NBR can be divided into five categories: ultra-high, high, medium high, medium and low acrylonitrile according to the content of ACN. There are two production modes: continuous polymerization and intermittent polymerization. Continuous polymerization is usually used in the production of few varieties and high yield with low consumption. Batch polymerization is suitable for multi variety and small batch production, and the engineering construction consumption is high.
Although nitrile rubber has excellent physical, mechanical and processing properties, its performance in acid gasoline and high temperature (150 ℃) environment for a long time is not as good as fluor rubber and acrylate rubber. Therefore, hydrogenated nitrile rubber (HNBR) with excellent performance was developed. In addition, nitrile rubber with ultra-cold resistance and high purity and carboxyl nitrile rubber (XNBR) were also developed.
Nitrile rubber has better heat resistance than natural rubber and styrene butadiene rubber. Its long-term service temperature can reach 100 ℃, and 120 ℃ can be used for 40 days.
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 meet various applications. In general purpose rubber, NBR rubber has better resistance to benzene, petroleum-based oil and non-polar solvent than NR, SBR, IIR and other non-polar rubber, and also better than polar CR.
Short comments: NBR has excellent oil resistance, high wear resistance, good heat resistance and strong adhesion. The gasket made of NBR is a good choice for steel drum closures, which can be provided by Xuheng and other gaskets like EPDM and PE are also available.