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Nitrile rubber tips

November 4, 2021

 

     Nitrile rubber is produced by emulsion polymerization of butadiene and acrylonitrile. Nitrile rubber

 

is mainly produced by low-temperature emulsion polymerization. It has excellent oil resistance,

 

high abrasion resistance, good heat resistance, and strong adhesion. .

 

     Its disadvantages are poor low temperature resistance, poor ozone resistance, poor insulation performance,

 

and slightly lower elasticity. Nitrile rubber is mainly used to make oil-resistant rubber products.

 

    Abbreviated as NBR, a synthetic rubber made by copolymerizing butadiene and acrylonitrile. It is a synthetic

 

rubber with good oil resistance (especially alkane oil) and good aging resistance. The acrylonitrile

 

content (%) in nitrile rubber has five types: 42-46, 36-41, 31-35, 25-30, 18-24. The more acrylonitrile content,

 

the better the oil resistance, but the cold resistance decreases accordingly. It can be used for a long time in

 

the air at 120°C or in the oil at 150°C. In addition, it also has good water resistance, air tightness and excellent

 

bonding properties. Widely used in the manufacture of various oil-resistant rubber products, a variety of

 

oil-resistant gaskets, gaskets, casings, flexible packaging, flexible hoses, printing and dyeing rubber rollers,

 

cable rubber materials, etc. It has become indispensable in industries such as automobiles, aviation, petroleum

 

, and copying. The elastic material.

 

     NBR has excellent oil resistance. Butadiene monomers can be copolymerized into three

 

different chain structures: cis, trans, and 1,2-alkylene groups. In a typical NBR structure, the trans form

 

accounts for about 78%. Because NBR contains cyano groups in its molecular chain structure,

 

its oil resistance (such as mineral oil, liquid fuel, animal and vegetable oil and solvent resistance) is

 

better than natural rubber, neoprene rubber and styrene butadiene rubber. Compared with other rubbers,

 

NBR has a wider range of operating temperature. Its long-term use temperature is 120oC. At the same time,

 

NBR has good low-temperature resistance, and the lowest glass transition temperature can reach -55oC.

 

 

   NBR has good chemical resistance and good processing performance. With the content of propionitrile

 

in its structure, its relative density increases, the vulcanization speed increases, and the tensile strength

 

performance increases, but the resilience performance decreases and the cold resistance deteriorates.

 

    Since the cyano group in NBR is easy to be polarized by electric field, the dielectric performance

 

is reduced, and it is a semiconducting rubber.

 

    NBR can be divided into five categories: ultra-high, high, medium-high, medium and low acrylonitrile

 

according to the level of ACN content. There are two production methods: continuous and batch polymerization.

 

   The continuous polymerization method is usually used for small variety and large-volume production,

 

with low consumption. The batch polymerization method is suitable for multi-variety and small batch production.

 

The number of polymerization tickets is small and the construction consumption is high.

 

So far, there is no trend of mutual substitution.

 

    Although nitrile rubber has excellent physical and mechanical properties and processing properties,

 

it is not as good as fluorine-like rubber and acrylic rubber in long-term use in sour gasoline and high

 

temperature (150oC) environments. For this reason, German companies, Canadian companies and

 

Japanese companies Developed hydrogenated nitrile rubber (HNBR) with excellent performance.

 

In addition, it has also developed ultra-cold-resistant and high-purity nitrile rubber and shuttle-based nitrile rubber (XNBR).