Hard rubber

Hard rubber has specific properties that make it suitable for various technical applications:

• High hardness: considerably harder than conventional elastomers, similar to plastics.

• Chemical resistance: resistant to acids, alkalis and oils.

• Insulating properties: excellent electrical insulator.

• Abrasion resistance: durable even under mechanical stress.

• Heat resistance: can be used at temperatures up to 100 °C (depending on the compound).

Hard rubber is produced by vulcanisation, in which rubber is crosslinked with a high proportion of sulphur (approx. 30 to 50 %). The process comprises several steps:

Steps in hard rubber production

• Mixing: raw rubber is mixed with sulphur, fillers and additives.

• Shaping: the material is brought into the desired shape (e.g. by pressing or extrusion).

• Vulcanisation: the shaped material is crosslinked under heat and pressure, which gives it its hardness and chemical stability.

• Post-processing: finishing such as cutting or grinding.

Depending on the requirements and composition, hard rubber is divided into different types:

Type	Properties	Typical applications
Standard hard rubber	High hardness, chemical-resistant	Seals, chemical containers
Electrically insulating hard rubber	High electrical insulating capacity	Electrical industry, cable insulation
Heat-resistant hard rubber	Resistant to higher temperatures	Automotive parts, machine elements
Fibre-reinforced hard rubber	Additional mechanical strength	Highly stressed components

Hard rubber is used in numerous industries, as it offers an ideal combination of strength, elasticity and chemical resistance:

Chemical industry

• Corrosion protection: lining of containers, pipes and reactors that come into contact with aggressive chemicals.

• Seals: for applications in chemical processes.

Automotive industry

• Bearings and seals: for engine and drive components.

• Shock absorbers: thanks to its high wear resistance and elasticity.

Electrical industry

• Insulators: for cables, switches and other electrical components.

• Protective housings: for electrical equipment in demanding environments.

Mechanical engineering

• Machine components: rollers, gears and other mechanical parts.

• Protective covers: for parts exposed to heavy stress.

Hard rubber offers numerous advantages that make it indispensable in industry:

• Durability: high wear and abrasion resistance thanks to hardnesses in the range of 90 Shore A.

• Chemical resistance: ideally suited for use in aggressive environments.

• Dimensional stability: retains its shape under mechanical and thermal stress.

• Versatility: suitable for numerous technical and industrial applications.

Despite its advantages, there are also challenges when using hard rubber:

• Brittleness: less flexible than soft rubber.

• Processing: manufacturing and post-processing require specialised methods.

• Costs: high-quality compounds can be expensive.

Property	Hard rubber	Soft rubber
Hardness	Very high	Low to medium
Flexibility	Limited	High
Temperature resistance	Higher	Limited
Chemical resistance	Very good	Good
Applications	Insulators, chemical containers	Seals, conveyor belts

• What is the difference between hard rubber and plastic? Hard rubber is more elastic than plastic and has higher chemical resistance, while plastic is often lighter and easier to shape.

• What temperatures can hard rubber withstand? Hard rubber can withstand temperatures of up to 100 °C, and even higher depending on the compound.

• Is hard rubber recyclable? Hard rubber can be recycled, but because it is crosslinked by vulcanisation, this is more complex than for thermoplastic materials.

• How is the surface of hard rubber finished? Hard rubber can be finished by grinding, polishing or milling to meet specific requirements.

Hard rubber offers a unique combination of hardness, chemical resistance and insulating capacity that makes it indispensable in numerous industries. Whether as corrosion protection in the chemical industry, as an insulator in electronics or as wear protection in mechanical engineering, hard rubber impresses with its versatility and durability.