Make a blog


1 year ago

Uses and applications for Nitrile-butadiene rubber (NBR)

Nitrile butadiene rubber (NBR) is a family of unsaturated copolymers of 2-propenenitrile and various butadiene monomers. Although its physical and chemical properties vary depending on the polymer’s composition of nitrile, this form of synthetic rubber is unusual in being generally resistant to oil, fuel, and other chemicals (the more nitrile within the polymer, the higher the resistance to oils but the lower the flexibility of the material).

The uses of nitrile rubber include disposable non-latex gloves, automotive transmission belts, hoses, O rings, gaskets, oil seals, V belts, synthetic leather, printer's form rollers, and as cable jacketing; NBR latex can also be used in the preparation of adhesives and as a pigment binder

Nitrile Rubber, or to give its full name, “Nitrile butadiene rubber (NBR)” is a type of synthetic rubber that is often used where resistance to fuel, oils and chemicals is required. It is also available with food approvals and can come in the form of extrusions, moldings or calendared sheet.

Like most unsaturated thermoses elastomers, NBR requires formulating with added ingredients, and further processing to make useful articles. Additional ingredients typically include reinforcement fillers, plasticizers, Protestants, and vulcanization packages. Processing includes mixing, pre-forming to required shape, and application to substrates, extrusion, and vulcanization to make the finished rubber article. Mixing and processing are typically performed on open mills, internal mixers, extruders, and calendars. Finished products are found in the marketplace as injection or transfer molded products (seals and grommets), extruded hose or tubing, calendared sheet goods (floor mats and industrial belting), or various sponge articles.

Although its temperature range is not quite as wide as Silicone Rubber, its fuel resistance and cost per kg makes it a more cost effective alternative to Fluor silicone or Vinton Extrusions.

Nitrile rubber, like styrene-butadiene rubber and other synthetic elastomers (elastic polymers), was a product of research that took place during and between the two world wars. A group of acrylonitrile-butadiene copolymers, given the name Buna N, was patented in 1934 by German chemists Erich Conrad and Eduard Tschunkur, working for IG Farben. Buna N was produced in the United States during World War II as GR-N (Government Rubber-Nitrile), and subsequently the group of acrylonitrile-butadiene elastomers became known as nitrile rubber.

Nitrile rubber is mostly used where high oil resistance is required, as in automotive seals, gaskets, or other items subject to contact with hot oils. The rolls for spreading ink in printing and hoses for oil products are other obvious uses. NBR is also employed in textiles, where its application to woven and nonwoven fabrics improves the finish and waterproofing properties.

NBR is and will continue to be a complex family of workhorse elastomers. The unique balance of oil, chemical, heat and cold resistance allows it to work well in a wide variety of automotive and industrial applications. The family is well differentiated to include general purpose types for cost sensitive applications and specialty products (XNBR, HotCrosslinked NBR, HNBR) for more demanding service conditions.