Nitrile butadiene rubber (NBR) is a copolymer made of acrylonitrile and butadiene monomer polymerization, mainly produced by low temperature emulsion polymerization, It has excellent oil resistance, high wear resistance, good heat resistance, strong adhesion. Its 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. Acrylonitrile content (%) in nitrile rubber is mainly classified as 42 ~ 46, 36 ~ 41, 31 ~ 35, 25 ~ 30, 18 ~ 24 . The more acrylonitrile content, the better the oil resistance, but the cold resistance is decreased accordingly. It can be used in air at 120 ° C or oil at 150 ° C for a long time. In addition, It also has good water resistance, air tightness and excellent bonding properties. Widely used in the production of a variety of oil-resistant rubber products, a variety of oil-resistant gaskets, gaskets, bushings, flexible packaging, soft hose, printing and dyeing roller, cable rubber materials, etc., in the automotive, aviation, petroleum, copying and other industries to become an essential elastic materials.
NBR has excellent oil resistance. Due to the cyanide group contained in the molecular chain structure of NBR, oil resistance (such as resistance to mineral oil, liquid fuel, animal and vegetable oils and solvents) is better than natural rubber, neoprene rubber and styrene butadiene rubber. Compared with other rubber, NBR has a wider range of use temperature, its long-term use temperature is 120℃, and NBR has good low temperature resistance, The lowest glass transition temperature can reach -55℃.
NBR has good chemical stability and good processing performance. With the increase of the relative density of acrylonitrile content in its structure, the vulcanization rate is accelerated, the tensile strength is improved, but the resilience is decreased and the cold resistance is poor. Because the cyanide group in NBR is easy to be polarized by electric field, the dielectric property is decreased, and it is a semiconductor rubber. NBR can be divided into 5 categories of ultra-high, high, medium and low acrylonitrile according to the level of ACN content. There are two kinds of production methods: continuous polymerization and intermittent polymerization. Continuous polymerization method is usually used for small variety and large volume production, low consumption. Batch polymerization method is suitable for multi-variety and small batch production, and the construction consumption is high.
Although nitrile rubber has excellent physical and mechanical properties and processing properties,It is not as good as fluorine rubber and acrylic rubber in acidic gasoline and high temperature (150℃) environment for a long time, So hydrogenated nitrile butadiene rubber (HNBR) with excellent properties was developed. In addition, nitrile butadiene rubber and carboxyl nitrile butadiene rubber (XNBR) with extremely ultra-cold resistance and high purity are developed.
