Hydrogenated Nitrile Rubber (HNBR) Detailed Introduction

Introduction

Hydrogenated nitrile rubber (HNBR) is a high-performance synthetic rubber made by hydrogenating nitrile rubber (NBR). HNBR has high heat resistance, chemical corrosion resistance and mechanical strength, and is widely used in automobiles, petrochemicals, aerospace and other fields. This article will introduce the chemical structure, performance characteristics, manufacturing process, application fields of HNBR and its comparison with other rubber materials in detail.

1. Chemical structure

The chemical structure of HNBR is mainly composed of hydrogenated nitrile rubber molecules, and its characteristics are as follows:

Hydrogenation reaction: Through hydrogenation reaction, the unsaturated double bonds (C=C) in nitrile rubber are saturated with hydrogen atoms to generate rubber molecules with higher saturation. This makes HNBR have better oxidation resistance, ozone resistance and chemical corrosion resistance.

Nitrile group: HNBR retains the nitrile group (-CN) of nitrile rubber, which makes it have excellent oil resistance and fuel resistance.

2. Performance characteristics

HNBR has the following outstanding performance characteristics:

Heat resistance:

Excellent high temperature resistance, usually can be used for a long time in a high temperature environment of 150°C (302°F), and can withstand temperatures up to 180°C (356°F) in a short period of time.

Good thermal stability, not prone to thermal aging.

Chemical corrosion resistance:

Excellent resistance to oils, fuels, aliphatic and aromatic hydrocarbons.

Acid, alkali and salt solution corrosion resistance.

Mechanical strength:

High tensile strength and tear strength, better than conventional nitrile rubber.

Good wear resistance and fatigue resistance.

Aging resistance:

Excellent oxidation and ozone resistance, extending service life.

Good resistance to ultraviolet radiation.

Low temperature performance:

Still maintain good elasticity in low temperature environment, usually can be used at low temperatures of -40°C to -55°C.

3. Manufacturing process

The manufacturing process of HNBR mainly includes the following steps:

Raw material preparation:

Use nitrile rubber as raw material, and add various additives such as vulcanizer, antioxidant, filler, etc. according to the formula.

Hydrogenation reaction:

Under the action of catalysts (such as palladium, platinum, etc.), the unsaturated double bonds in nitrile rubber react with hydrogen to generate hydrogenated nitrile rubber.

Control the reaction conditions (such as temperature, pressure, hydrogen flow) to ensure uniform hydrogenation of rubber molecules.

Post-treatment:

The hydrogenated rubber is post-treated, such as washing, drying, crushing, etc., to remove catalyst residues and unreacted raw materials.

Vulcanization molding:

Mix hydrogenated nitrile rubber with other additives, mold it by molding, extrusion or injection molding, and vulcanize it to improve its mechanical properties and heat resistance.

4. Application fields

HNBR is widely used in the following fields due to its excellent performance:

Automotive industry:

Engine parts: seals, O-rings, oil seals, belts, etc., used in engine oil circuits, fuel systems and cooling systems.

Transmission system: seals, shock absorbers, clutch parts, etc.

Petrochemical industry:

Seals: used for seals in high temperature, high pressure and corrosive media, such as valve seals, pipe seals, etc.

Hose and connectors: oil-resistant and chemical-resistant hoses and connectors.

Aerospace:

Aircraft parts: seals, shock absorbers, isolation pads, etc., used in high temperature, high pressure and vibration environments.

Propulsion system: sealing and shock-absorbing parts of rocket engines and spacecraft.

Industrial manufacturing:

Hydraulic system: hydraulic seals resistant to high pressure and high temperature.

Compressors and pumps: seals, piston rings, etc., used in high temperature, high pressure and corrosive environments.

V. Comparison with other rubber materials

Performance/material Hydrogenated nitrile rubber (HNBR) Nitrile rubber (NBR) Fluororubber (FKM) Silicone rubber (VMQ)

Heat resistance 150°C (302°F) 120°C (248°F) 200°C (392°F) 220°C (428°F)

Oil resistance Excellent Good Excellent Poor

Chemical corrosion resistance Excellent Good Excellent Good

Mechanical strength High Medium High Low

Aging resistance Excellent Good Excellent Excellent

Low temperature performance Good Medium Poor Excellent

Conclusion

As a high-performance synthetic rubber, hydrogenated nitrile rubber (HNBR) has excellent heat resistance, chemical corrosion resistance, mechanical strength and aging resistance. It is widely used in high temperature, high pressure and corrosive environments such as automobiles, petrochemicals, aerospace, etc., and shows excellent service life and reliability. By understanding the chemical structure, performance characteristics, manufacturing process and application areas of HNBR, we can better select and apply this high-performance material, thereby improving the reliability and safety of the system.

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