Acrylonitrile Butadiene Production
  • Nitrile (NBR) is much preferred by buyers because it has much of the same qualities of latex, but without the possible allergic reaction and it has much of the same quality as synthetic polyisoprene (aka. artificial latex), but without the costs.
  • Nitrile gloves are produced from acrylonitrile butadiene, a polymer of acrylonitrile and butadiene – both of which are by-products of the petro-chemical industry.
The Process
  • Acrylonitrile butadiene, or nitrile as it is more popularly known, is the number one choice for medical rubber glove use because it says many of the best qualities of natural rubber latex, whilst not being allergenic and being the cheapest amongst other synthetic rubbers.
  • In 2018, 4% of the world’s synthetic rubber production capacity is for NBR(1); this is up from 0.7% in 2012(2).
  • Nitrile rubber can be synthesized by copolymerizing acrylonitrile and 1,3-butadiene in an aqueous emulsion. Both are highly toxic and cancerous; however they tend to breakdown and dissipate quickly in air and water. It is also highly flammable.
  • NBR should be understood as complex family of unsaturated acrylonitrile and butadiene copolymers, the proportion of acrylonitrile and butadiene is dependent on the need.
  • The exact formula for acrylonitrile butadiene or nitrile (NBR) can be found in the Appendix.
  • Until recently price was largely driven by the price oil due to the polymer being largely a by-product from petro-chemicals.
  • There was roughly 1300 to 1400 tons produced in 2019, which was just greater consumption for that year(3).

Source:

1: https://www.rubbernews.com/suppliers/sr-market-still-struggling-overcapacity

2. https://www.rubbernews.com/suppliers/sr-market-still-struggling-overcapacity

3.  Own estimation based on several sources

Acrylonitrile – CH2CHCN
  • It is a colourless volatile liquid. It evaporates quickly into air at room temperature.
  • The largest producer of acrylonitrile is INEOS(4)
  • It is produced by catalytic(5) ammoxidation, an industrial process for the production of nitriles using ammonia and oxygen, of propylene (a chemical from the petro-chemical industry). This is known as the SOHIO process(6).
SOHIO Process

  • There are ‘green alternatives’ being produced using biomass, though they cannot currently compete with the current SOHIO process in terms of cost.

Source:

4. https://www.ineos.com/globalassets/ineos-group/businesses/ineos-nitriles/she/acrylonitrile_brochure.pdf

5.  A catalyst to speed up an reaction

6. http://www.designlife-cycle.com/life-cycle-of-nitrile-rubber-gloves

  • Acrylonitrile is commonly delivered to storage in bulk by lorry, rail car, pipeline, barge or ship. It is also delivered in drums.
Acrylonitrile Storage
  • It lasts only up to six months in optimum storage conditions. (This is can be controlled for with polymer inhibitors).
  • Storage tanks should be in the open air and be constructed of stainless steel or carbon steel and surrounded by a dike wall.
  • Acrylonitrile storage tanks normally do not require insulation or refrigeration. However, in extremely hot climates, insulation and refrigeration should be considered in tank design. White paint is recommended for the exterior surface to minimise interior temperature increases.
Butadiene – (CH2=CH)2
  • Butadiene is a gas under normal environmental conditions.
  • Butadiene is extremely flammable and reactive. It presents a significant fire and explosion hazard. It is highly reactive, non-corrosive gas.
  • INEOS is the number one producer in Europe – producing 350ktes at locations in France, the UK and Germany.
  • It can be produced from hydrocarbons, it is a by-product of butane and ethylene and other alkenes through steam cracking. It can also be produced from ethanol.
  • Although production from ethanol is less cost-effective than from steam cracking it is made on smaller volumes in South America, Eastern Europe, China, and India. This method was first created in the Soviet Union in the 1930s.
  • Butadiene is stored in a similar manner to natural gas, in large pressurised metal cylindrical containers.
Butadiene Storage
  • Butadiene is stored in a similar manner to natural gas, in large pressurised metal cylindrical containers.
Acrylonitrile butadiene or nitrile (NBR) Production
  • It is made up of between butadiene (50% – 82%) and acrylonitrile (18 % – 50 %) depending on what material is needed.
  • For optimal low-temperature flexibility and solvent resistance, the acrylonitrile content is about 33%; however, the higher the acrylonitrile content, the more resistant the nitrile will be to nonpolar solvents, like hydrocarbons, e.g. petrol.
  • There is about 2% loss (by weight) of the constituent chemicals during the polymerisation(7).

Source:7. https://www.versalis.eni.com/irj/go/km/docs/versalis/Contenuti%20Versalis/IT/Documenti/La%20nostra%20offerta/Licensing/Elastomeri/NBR.pdf

  • It is created from water, emulsifier/soap, monomers (butadiene and acrylonitrile), radical   generating activator, and other ingredients are introduced into the polymerization vessels.
  • The emulsion process yields polymer latex, which is coagulated using various materials (e.g. calcium chloride and aluminium sulphate) to form crumb rubber, which is dried and compressed into bales(8).
  • Styrene-butadiene (SBR) and Acrylonitrile butadiene (NBR) production is largely interchangeable and it takes a relatively short-time to flip production.
    • Synthomer, the 2nd largest producer of SBR has announced in August 2020 that it was converting some of its SBR production to NBR for the increase in demand in nitrile gloves.
  • NBR is chemically stable and doesn’t degrade for a long-time.
  • NBR prices have been largely tied to the cost petro-chemicals for much of the past four years averaging around $1.00 USD. There was a slight price rally in early 2020, but the cost of NBR has been falling for nearly two years and was cheaper per kg than NR in May 2020(9).
Cost
  • NBR prices have been largely tied to the cost petro-chemicals for much of the past four years averaging around $1.00 USD. There was a slight price rally in early 2020, but the cost of NBR has been falling for nearly two years and was cheaper per kg than NR in May 2020(9).
Nitrile Glove Production
  • The manufacturing equipment first runs ceramic, hand-shaped formers through water and bleach to clean them and remove any residue from the previous run. The formers then dry to remove all the water.
  • Then, they dip in a mixture of calcium carbonate and calcium nitrate, which helps the synthetic materials coagulate around the formers. Afterward, the formers dry again.
  • The equipment dips the formers in tanks full of NBR.
  • The following step involves heating the materials at a high temperature to form the gloves as they dry.
  • For easier donning, nitrile gloves undergo one of two processes: chlorination or polymer coating. Chlorination involves exposing the gloves to chlorine – as an acid mixture or gas – to make the material harder and more slick.
  • Polymer coating lubricates the glove surface by adding a layer of polymer.
  • The gloves are removed from the hand-shaped formers.

Source:

8. http://www.kpatents.com/assets/files/applications/4.03.08_synthetic_latex_nitrile_butadiene_rubber.pdf

9. http://www.samso.com.au/post/covid-proof-stock-that-is-not-related-to-gold

  • Finally tests are made on the gloves by filling a proportion with water and checking for leaks.
  • According to Malaysian Rubber Glove Manufacturers Association (MARGMA):

“Malaysia’s demand is 120 million gloves per annum, which takes up only about six to seven hours of production time for all the manufacturers.”

  • To note, latex rubber glove production is interchangeable with nitrile glove production.