Black car tyre manufactured from rubber compounds.
Application

Rubber compounds

Elastomers are dimensionally stable, elastically deformable plastics which revert to their original shape

In addition to thermoplastics and thermosets, elastomers are the third important main plastics group. Elastomers are dimensionally stable, but elastically deformable plastics with a glass transition point below room temperature. The plastics can be deformed under tension, shearing and pressure loads, but then revert to their original not deformed shape.

From a chemical aspect, elastomers are macromolecules which are only irreversibly joined by a few wide-mesh cross-linking bridges. These cross-links can be degraded for thermoplastic elastomers under the influence of heat, so that they demonstrate thermoplastic behaviour.

Modifications to rubber compounds enable the manufacturing of elastomers with customized degrees of hardness, conductive network densities and operation temperatures.

Typical areas of application

Sealing rings in black, red and white from rubber compounds
Black car tyres manufactured from rubber compounds.
Black sealing rings from rubber compounds
Small, black-grey pellets from a treatment process for rubber compounds
Black pellets from a treatment process for rubber compounds
Black granules from rubber compounds, manufactured using modern compounding technology
Rubber boots from elastomers
Schwarze Autoreifen gestapelt, als Beispiel für die Herstellung von Rubber Compounds

Excavations in Guatemala have shown that already in the 3rd century, the Maya knew rubber as a material. Since the 18th century, more and more applications have been described.

The invention of the vulcanization process by Charles Goodyear in 1839 enabled stable elastic properties both in cold and hot conditions and thus also the breakthrough to technical applications. At the beginning of the twentieth century, German chemists succeeded in producing synthetic rubber.

Further insights into our options for the car and tyre industry

Benefits

BUSS compounding systems offer the following specific benefits

A large number of mixing cycles is achieved with the multiple-flight Co-Kneaders in the compounding machinery. The unique new screw geometries enable maximized splitting and recombining of the compounds, with numerous striations and excellent mixing over a very short process length.

BUSS compounding technology allows high filler loadings by splitting to 2-3 feed positions, use of feed-in processes such as side feeders, gravimetric dosing units, back venting and excellent conveying efficiency. The Co-Kneader's moderate shear rates allow effortless handling of the high viscosities arising with high filler loadings.

Uniform shear rates allow controlled mixing at lower temperatures whilst imparting only the required shear energy for the task at hand. The narrow shear rate distribution compared to alternative compounding systems ensures uniform shear histories for every individual particle. This results in high-quality processing with reduced energy input.

Thanks to even, moderate shear rates in the entire screw channel, the BUSS Co-Kneader can retain a narrow, defined temperature range and the temperature peaks from other compounding systems can be avoided. This allows precise adherence to a low temperature range for the entire processing length.

Volatile substances are usually degraded by vacuum degassing at the end of the process section or additionally in the discharge unit. The high number of mixing cycles, shearing and rearrangements of the BUSS Co-Kneader technology ensures a continuous renewal of the compound surface. In this way, air inclusion or volatile components can be minimized highly efficiently.

Injection pins, which can be mounted at any position along the process section in the BUSS Co-Kneader, allow liquid components to be injected directly into the molten polymer at the optimum location for the process. The mixing process begins immediately, without smearing on the barrel wall and enables mixing over the shortest possible process length.

Compounding requirements

of rubber compounds

The traditional production method for elastomers is preparation on internal mixers or rolling mills. This established process provides advantages such as maximum flexibility, precise offline dosage of even the smallest formulation proportions, as well as variable dwell and mixing times.

However, limitations such as high specific energies, interim storage times and also property fluctuations between individual batches emphasize the advantages of continuous processing in the compounding machine: the typical strength profile includes uniform process conditions, narrow residence time distribution and the integration of process steps.

With precise temperature control, the BUSS Co-Kneader can also offer the option to mix high filler proportions excellently and at the same time gently and to inject liquid formulation components such as plasticizer oils or reagents directly into the process chamber at the optimum position.

The wide use of the BUSS Co-Kneader as a processing system for silicone and fluororubber has been known for several decades and highly valued by its users.

Recently, a wide range of further application fields has been added to BUSS compounding technology: here, the integration of process steps, the extension of requirements profiles and the use of alternative formulation components play the major roles.

These high requirements are accommodated and implemented using sophisticated processes. The processes are developed, optimized and also the initial scale-up steps can be realised with a throughput factor of 10 at the BUSS technical centre.

If required, two BUSS Co-Kneader stages can be combined. The pressure build-up step is strictly decoupled from the preparation process here. Thus, the process steps can be optimized, independently of each other. Here, normally a flange-mounted discharge extruder is used as a pressure build-up device for granulation or further processing.

The BUSS Co-Kneader's hinged housing ensures fast access to and high availability of the compounding system. The modular and therefore adjustable structure of the entire compounding system and the widely supported BUSS process expertise make the BUSS Co-Kneader system an excellent choice for compounding elastomers and rubber compounds.

Typical plant layout

Typical compounding plant layout for manufacturing rubber compounds

COMPEO compounder for rubber compound production

Take a look at our typical plant layout for rubber compounds in our COMPEO showroom.

Get to know our COMPEO compounder series

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COMPEO series

We present: COMPEO, the state-of-the-art compounder that offers more versatility in its application, higher flexibility in process engineering, and increased added value in compound manufacturing.

Rubber Compounds Fact Sheet

Thanks to their flexible, elastic and insoluble properties, elastomers have fundamental uses in all branches of industry.

Plant and System Solutions

Custom compounding systems from BUSS: tailor-made concepts, integration of all components, precise assembly, and smooth commissioning. Comprehensive expertise results in sustainable compounding solutions for a wide range of material applications.