What is the difference between nitrile and NBR?

Chemical compound

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Nitrile rubber, also known as nitrile butadiene rubber, NBR, Buna-N, and acrylonitrile butadiene rubber, is a synthetic rubber derived from acrylonitrile (ACN) and butadiene.[1] Trade names include Perbunan, Nipol, Krynac and Europrene. This rubber is unusual in being resistant to oil, fuel, and other chemicals.

NBR is used in the automotive and aeronautical industry to make fuel and oil handling hoses, seals, grommets, and self-sealing fuel tanks. It is also used in the food service, medical, and nuclear industries to make protective gloves. NBR's stability at temperatures from &#;40 to 108 °C (&#;40 to 226 °F) makes it an ideal material for aeronautical applications. Nitrile butadiene is also used to produce moulded goods, footwear, adhesives, sealants, sponges, expanded foams, and floor mats.

Its resilience makes NBR a useful material for disposable lab, cleaning, and examination gloves. Nitrile rubber is more resistant than natural rubber to oils and acids, and has superior strength, but has inferior flexibility.

History

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Nitrile rubber was developed in at BASF and Bayer, then part of chemical conglomerate IG Farben. The first commercial production began in Germany in .[2][3]

IG Farben plant under construction approximately 10 kilometres (6.2 mi) from Auschwitz,

The Buna-Werke was a slave labor factory located near Auschwitz and financed by IG Farben. The raw materials came from the Polish coalfields.[4] Buna rubber was named by BASF A.G., and through Buna was a remaining trade name of nitrile rubber held by BASF.

Production

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Krynac F nitrile rubber bales

Emulsifier (soap), acrylonitrile, butadiene, radical generating activators, and a catalyst are added to polymerization vessels in the production of hot NBR. Water serves as the reaction medium within the vessel. The tanks are heated to 30&#;40 °C to facilitate the polymerization reaction and to promote branch formation in the polymer. Because several monomers capable of propagating the reaction are involved in the production of nitrile rubber the composition of each polymer can vary (depending on the concentrations of each monomer added to the polymerization tank and the conditions within the tank). There may not be a single repeating unit throughout the entire polymer. For this reason there is also no IUPAC name for the general polymer.

Monomers are usually permitted to react for 5 to 12 hours. Polymerization is allowed to proceed to ~70% conversion before a &#;shortstop&#; agent (such as dimethyldithiocarbamate and diethylhydroxylamine) is added to react with (destroy) the remaining free radicals and initiators. Once the resultant latex has &#;shortstopped&#;, the unreacted monomers are removed through a steam in a slurry stripper. Recovery of unreacted monomers is close to 100%. After monomer recovery, latex is sent through a series of filters to remove unwanted solids and then sent to the blending tanks where it is stabilized with an antioxidant. The yielded polymer latex is coagulated using calcium nitrate, aluminium sulfate, and other coagulating agents in an aluminium tank. The coagulated substance is then washed and dried into crumb rubber.[3]

The process for the production of cold NBR is very similar to that of hot NBR. Polymerization tanks are cooled to 5&#;15 °C instead of heating up to 30&#;40 °C close to ambient temperature (ATC). Under lower temperature conditions, less branching will form on polymers (the amount of branching distinguishes cold NBR from hot NBR).

Properties

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The raw material is typically yellow, although it can also be orange or red tinted, depending on the manufacturer. Its elongation at break is &#; 300% and possesses a tensile strength of &#; 10 N/mm2 (10 MPa). NBR has good resistance to mineral oils, vegetable oils, benzene/petrol, ordinary diluted acids and alkalines.

An important factor in the properties of NBR is the ratio of acrylonitrile groups to butadiene groups, referred to as the ACN content. The lower the ACN content, the lower the glass transition temperature; however, the higher the ACN content, the better resistance the polymer will have to nonpolar solvents as mentioned above.[5] Most applications requiring both solvent resistance and low temperature flexibility require an ACN content of 33%.

Property Value Appearance Hardness, Shore A 30&#;90 Tensile failure stress, ultimate 500- PSI Elongation after fracture in % 600% maximum Density Can be compounded around 1.00 g/cm3

Applications

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A disposable nitrile rubber glove

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.[citation needed]

Unlike polymers meant for ingestion, where small inconsistencies in chemical composition/structure can have a pronounced effect on the body, the general properties of NBR are insensitive to composition. The production process itself is not overly complex; the polymerization, monomer recovery, and coagulation processes require some additives and equipment, but they are typical of the production of most rubbers. The necessary apparatus is simple and easy to obtain.

In January , the European Commission imposed fines totaling &#;34,230,000 on the Bayer and Zeon groups for fixing prices for nitrile butadiene rubber, in violation of the EU ban on cartels and restrictive business practices (Article 81 of the EC Treaty and Article 53 of the EEA Agreement).[6]

Hydrogenated nitrile butadiene rubber (HNBR)

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Hydrogenated nitrile butadiene rubber (HNBR) is produced by hydrogenation of NBR. Doing so removes the olefinic groups, which are vulnerable to degradation by various chemicals as well as ozone. Typically, Wilkinson's catalyst is used to promote the hydrogenation. The nitrile groups are unaffected. The degree of hydrogenation determines the kind of vulcanization that can be applied to the polymer.[7]

Also known as highly saturated nitrile (HSN), HNBR is widely known for its physical strength and retention of properties after long-term exposure to heat, oil, and chemicals. Trade names include Zhanber (Lianda Corporation), Therban (Arlanxeo [8]), and Zetpol (Zeon Chemical). It is commonly used to manufacture O-rings for automotive air-conditioning systems.[9] Other applications include timing belts, dampers, servo hoses, membranes, and seals.[10]

Depending on filler selection and loading, HNBR compounds typically have tensile strengths of 20&#;31 MPa at 23 °C. Compounding techniques allow for HNBR to be used over a broad temperature range, &#;40 °C to 165 °C, with minimal degradation over long periods of time. For low-temperature performance, low ACN grades should be used; high-temperature performance can be obtained by using highly saturated HNBR grades with white fillers. As a group, HNBR elastomers have excellent resistance to common automotive fluids (e.g., engine oil, coolant, fuel, etc.).

The unique properties and higher temperature rating attributed to HNBR when compared to NBR has resulted in wide adoption of HNBR in automotive, industrial, and assorted, performance-demanding applications. On a volume basis, the automotive market is the largest consumer, using HNBR for a host of dynamic and static seals, hoses, and belts. HNBR has also been widely employed in industrial sealing for oil field exploration and processing, as well as rolls for steel and paper mills.

Carboxylated nitrile butadiene rubber (XNBR)

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An alternative version of NBR is carboxylated nitrile butadiene rubber (XNBR). XNBR is a terpolymer of butadiene, acrylonitrile, and acrylic acid.[11] The presence of the acrylic acid introduces carboxylic acid groups (RCO2H). These groups allow crosslinking through the addition of zinc (Zn2+) additives. The carboxyl groups are present at levels of 10% or less. In addition to these ionic crosslinks, traditional sulfur vulcanization is applied.

See also

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References

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Working Temperature Range:

High: 212°F / 100°C Low: -22°F / -30°C

What is Nitrile Rubber?

Nitrile rubber is also called nitrile butadiene rubber, NBR, Buna-N and acrylonitrile butadiene rubber. It is a synthetic rubber, and is usually the ideal choice for any product that requires petroleum (oil or gas) resistance.  

This material, like many other synthetic rubbers, gained popularity during World War II when natural rubber resources were in short supply around the globe. Different versions of the same polymer were created in different countries, but the U.S. version of Nitrile rubber was called Buna-N. 

Today, Nitrile rubber is used mainly when an application requires a resistance to petroleum. It is a common base for gaskets, O-rings and other types of seals.

If Nitrile rubber is the ideal material for your application, give Custom Rubber a call. Even if you aren&#;t certain, our team of experts can help guide you. Contact Custom Rubber Corp. for answers to your Nitrile rubber questions.

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Advantages of Nitrile Rubber

Nitrile rubber&#;s biggest advantage is its resistance to petroleum, but it also has several other desirable properties. 

• Excellent abrasion resistance
• Good tear resistance
• Low compression set

Disadvantages of Nitrile Rubber

Nitrile rubber is not ideal in applications that require prolonged exposure to ozone or heat. Disadvantages include:

• Poor ozone, weather and sun resistance
• Moderate operating temperature range
• Low flame resistance

Commonly Asked Questions About Nitrile Rubber

The following questions regarding Nitrile rubber applications, properties and uses are frequently asked by our customers. Custom Rubber Corp. is here to provide answers and assist in your decision making process.
 

Q: What is Nitrile rubber used for?

A: Nitrile rubber is primarily used in applications requiring oil or solvent resistance. Solvents are materials that are oil-based, like paint thinners, turpentine, MEK, etc. Choose Nitrile when your end product will come in contact with these or other oil-based materials.

At Custom Rubber, we have used Nitrile rubber to make bumper pieces that slide along a greased track as well as nitrile rubber seals used for underground conduits. We have also blended Nitrile rubber and PVC plastic to create heavy duty power distribution products, like the wires strung with lights used to illuminate construction sites. 

Throughout the industry, Nitrile rubber is often used to create latex-alternative rubber gloves, oil-resistant footwear, floor mats, transmission belts for cars, synthetic leather, V belts and as a component of different adhesives. 
 

Q: Is Nitrile a natural rubber?

A: No, Nitrile rubber is not a natural rubber. It is a human-made, synthetic material. For more information on this topic,
 

Q: How long does Nitrile rubber last?

A: Nitrile rubber&#;s lifespan, like nearly all rubber materials, depends on how it is formulated, stored and applied. Nitrile rubber exposed to the elements can have an extremely short life whereas Nitrile rubber kept immoible in a dark storage cabinet will last the longest. 
 

Q: How can I extend the life of Nitrile rubber?

A: Take good care of your Nitrile rubber by keeping it away from ozone, heat, sun and weather. When not in use, store it in an ozone proof bag.
 

Q: Is Nitrile rubber poisonous?

A: Nitrile rubber is not poisonous, but we would not recommend eating a bowl of it for breakfast. Like many synthetics, you can actually formulate Nitrile rubber with all FDA-approved ingredients, but again, that doesn&#;t mean it&#;s great for the human body to digest. 
 

Q: How do I moisturize Nitrile rubber?

A: Strictly speaking, there is no great way to moisturize Nitrile rubber. A Nitrile product outside exposed to ozone will inevitably dry and crack. Instead, buy a new part and keep it out of the sun, or use a different type of rubber if the part must stay exposed to sunlight.

Q: Where are Nitrile rubber gloves used?

A:  Nitrile rubber can be used in place of natural rubber latex to create rubber gloves if the user is allergic to latex. Nitrile rubber is also much more puncture-resistant than natural rubber, making it an ideal alternative in situations where rubber gloves risk tearing or breakage.
 

Q: What is the difference between Nitrile and Neoprene rubber?

A: Both Nitrile and Neoprene rubbers are synthetics with good abrasion and tear resistance. The main difference between the two is that Nitrile rubber is much more oil resistant.
 

Q: What&#;s the difference between Buna-N and NBR?

A: Nitrile rubber, Buna-N and NBR are all different names for the same thing. They are used interchangeably. 
 

Q: What&#;s the difference between HNBR and NBR?

A: Hydrogenated nitrile butadiene rubber (HNBR) is made by hydrogenating Nitrile rubber. This change makes the end material stronger against heat and chemicals. It is most commonly used in the manufacturing of O-rings for your car&#;s air conditioning system, but can be used to create other parts, like seals and membranes, that go into end products. HNBR is more expensive than regular Nitrile rubber.
 

Q: What&#;s the difference between XNBR and NBR?

A: Carboxylated nitrile butadiene rubber (XNBR) is another formulation of Nitrile rubber that also serves to strengthen the end material. It is also available at an increased cost. Production of both XNBR and HNBR are significantly more expensive than regular Nitrile rubber and are only necessary in limited applications.

Q: What is the average price of Nitrile rubber?

A: There is no exact answer to this question as the price depends on the raw materials market, which is constantly fluctuating. But in comparison to other types of rubber, the price of Nitrile rubber is not overly expensive.
 

Q: Is Nitrile rubber good for O-rings?

A: Yes! Nitrile rubber is good for O-rings because its ideal application is in creating a seal when oil is present. O-Rings are used for fluid sealing. Nitrile rubber provides a cost effective way to create these seals.

 

Q: How does Nitrile rubber compare to other rubber materials?

  MATERIAL ABBREVIATION VIBRATION
ISOLATION RELATIVE PRICE TEMPERATURE RANGE OZONE, UV RESISTANCE OIL RESISTANCE

Natural

NR Excellent Good -60F to 220F Poor Poor

Butyl

IIR Excellent Fair -75F to 250F Good Poor

Ethylene-Propylene

EPDM Good Excellent -70F to 250F Excellent Poor

Nitrile

NBR Good Good -30F to 250F Poor Excellent

Neoprene / Chloroprene

CR Excellent Excellent -60F to 220F Good Fair

Silicone

VMQ Good Fair -175F to 450F Excellent Fair  

Q: How can I purchase Nitrile rubber parts and products?

The following questions regarding Nitrile rubber applications, properties and uses are frequently asked by our customers. Custom Rubber Corp. is here to provide answers and assist in your decision making process.A: Nitrile rubber is primarily used in applications requiring oil or solvent resistance. Solvents are materials that are oil-based, like paint thinners, turpentine, MEK, etc. Choose Nitrile when your end product will come in contact with these or other oil-based materials.At Custom Rubber, we have used Nitrile rubber to make bumper pieces that slide along a greased track as well as nitrile rubber seals used for underground conduits. We have also blended Nitrile rubber and PVC plastic to create heavy duty power distribution products, like the wires strung with lights used to illuminate construction sites.Throughout the industry, Nitrile rubber is often used to create latex-alternative rubber gloves, oil-resistant footwear, floor mats, transmission belts for cars, synthetic leather, V belts and as a component of different adhesives.A: No, Nitrile rubber is not a natural rubber. It is a human-made, synthetic material. For more information on this topic, we've published an article explaining the difference between natural and synthetic rubber here. A: Nitrile rubber&#;s lifespan, like nearly all rubber materials, depends on how it is formulated, stored and applied. Nitrile rubber exposed to the elements can have an extremely short life whereas Nitrile rubber kept immoible in a dark storage cabinet will last the longest.A: Take good care of your Nitrile rubber by keeping it away from ozone, heat, sun and weather. When not in use, store it in an ozone proof bag.A: Nitrile rubber is not poisonous, but we would not recommend eating a bowl of it for breakfast. Like many synthetics, you can actually formulate Nitrile rubber with all FDA-approved ingredients, but again, that doesn&#;t mean it&#;s great for the human body to digest.A: Strictly speaking, there is no great way to moisturize Nitrile rubber. A Nitrile product outside exposed to ozone will inevitably dry and crack. Instead, buy a new part and keep it out of the sun, or use a different type of rubber if the part must stay exposed to sunlight.A: Nitrile rubber can be used in place of natural rubber latex to create rubber gloves if the user is allergic to latex. Nitrile rubber is also much more puncture-resistant than natural rubber, making it an ideal alternative in situations where rubber gloves risk tearing or breakage.A: Both Nitrile and Neoprene rubbers are synthetics with good abrasion and tear resistance. The main difference between the two is that Nitrile rubber is much more oil resistant.A: Nitrile rubber, Buna-N and NBR are all different names for the same thing. They are used interchangeably.A: Hydrogenated nitrile butadiene rubber (HNBR) is made by hydrogenating Nitrile rubber. This change makes the end material stronger against heat and chemicals. It is most commonly used in the manufacturing of O-rings for your car&#;s air conditioning system, but can be used to create other parts, like seals and membranes, that go into end products. HNBR is more expensive than regular Nitrile rubber.A: Carboxylated nitrile butadiene rubber (XNBR) is another formulation of Nitrile rubber that also serves to strengthen the end material. It is also available at an increased cost. Production of both XNBR and HNBR are significantly more expensive than regular Nitrile rubber and are only necessary in limited applications. Not sure which formulation is best for you? We can help you out. Contact Custom Rubber Corp. here. A: There is no exact answer to this question as the price depends on the raw materials market, which is constantly fluctuating. But in comparison to other types of rubber, the price of Nitrile rubber is not overly expensive.A: Yes! Nitrile rubber is good for O-rings because its ideal application is in creating a seal when oil is present. O-Rings are used for fluid sealing. Nitrile rubber provides a cost effective way to create these seals.

The Custom Rubber Corp. team has extensive experience in helping customers formulate Nitrile based rubber for their application and then designing parts that are manufacturable while meeting customer needs.

Is Nitrile rubber right for your application? Contact the Custom Rubber Corp. team today.

Contact us to discuss your requirements of Nitrile rubber NBR. Our experienced sales team can help you identify the options that best suit your needs.

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