Power boxes consisting of heat-hardening plastics (thermosets)
Application

Compounding technology for thermosets

Thermosets are rigid polymer materials which are cross-linked three-dimensionally after hardening

The thermoset materials group, also referred to as duromers, is a group of plastics which can no longer be deformed after hardening. It is one of the three groups according to which polymers can be categorised:

This is distinguished dependent on the extent of macromolecule chain crosslinking in thermoplastics, elastomers or just thermosets. Whereas the thermoplastics have no crosslinking points and are therefore fusible, elastomers and thermosets cannot be fused due to their crosslinking and decompose after exceeding the decomposition temperature (pyrolysis). The thermoset Bakelite, a phenoplastic, is recognised as the first industrially produced plastic at the beginning of the 20th century.

Typical areas of application

Thermoset cable bridges are used due to their good insulation.
Angle section consisting of heat-hardening plastic. Thermosets are manufactured using compounding systems
Gold-coloured thermoset components for the motor compartment
White, pulverized granulate, manufactured using special compounding technology for thermosets
Black granulate, produced using special compounding technology for thermosets

Thermosets are hard, glass-like polymer materials which are permanently cross-linked three-dimensionally via chemical primary valence bonding. The cross-linkage takes place when mixing pre-products with branch points and is either activated at room temperature chemically using catalysers or thermally at high temperatures.

The high crosslinking density poses high requirements of the compounding technology for heat-hardening plastic. It is responsible for the very high thermo-mechanical rigidity, excellent electrical properties and the exceptional chemical resistance.

The respective fields of use for the compounding technology are defined from these property profiles. Thus, for example the high-performance thermosets in the car industry for technical parts in the engine compartment or the drive sections are used where their temperature resistance under considerable load is particularly valued.

In electrotechnology, the combination of insulation properties, the advantageous fire behavior and dimensional stability are the reasons for their use. Good resistance to various substances and liquids make thermosets a valued choice for both food- and chemicals applications.

Further insights into our options for the plastics industry

Benefits

BUSS compounding systems offer the following specific benefits

The separate execution of compounding in the BUSS Co-Kneader and pressure build-up in the discharge unit enables processing at low pressures and temperatures. Thus, the configuration of application-specific screw geometries in each process zone can guarantee an optimized temperature profile in each process zone.

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

The BUSS Co-Kneader allows precise temperature control due to controlled energy input and uniform, moderate shear rates as well as their temperature monitoring by thermocouples, which are mounted in drilled kneading pins surrounded by polymer at relevant positions along the process section.

Latest generation multi-flight BUSS compounders achieve a better mixing effect with a low overall specific energy input. This is because there is a high number of mixing cycles, optimally attuned to the respective process zone. The energy required for melting is almost exclusively introduced mechanically (dissipated) as shear energy.

The BUSS Co-Kneader guarantees intense distributive mixing, as the superimposition of rotation and axial movement of the mixing and kneading screw causes flow separations and a large number of shearing surfaces, thereby generating cross-channel mixing.

Compounding requirements

for thermosets

The preparation step for thermosets takes place using polymer pre-products, glass or carbon reinforcement fibers, fillers or also natural fibers. In several cases, the corresponding reaction systems for final thermosetting are also used.

In addition to the gentle integration of the additives, adherence to the absolute temperature limit below the final conductive temperature is the central requirement. This succeeds with BUSS compounding technology and in particular with the BUSS Co-Kneader due to its working principle during which a relaxation sequence follows each gentle shear cycle in an excellent manner. Optimum process temperatures can be proven at all times due to exact measurement of the product temperature via drilled kneading pins.

Customized material solutions are responsible for an economical service life. The economical throughputs and all the advantages of continuous production means such as extremely constant and trackable product quality, a high utilization degree and availability of the systems round off the excellent suitability of BUSS Co-Kneader technology.

After the preparation step, the products are rolled out and broken. For some product groups such as phenoplasts and melamine resins, hot granulation is also possible. This results in further product benefits compared to alternative preparation methods.

Augmented with the widely supported BUSS compounding process expertise, the BUSS Co-Kneader is the first choice for continuous compounding of thermosets. The large number of systems installed in the field long since bears witness to this.

Typical plant layout

Aminoplasts

Typisches Anlagenlayout, das für die Herstellung von Aminoplaste verwendet wird

Typical plant layout

Phenol compounds

Typical plant layout

Epoxy moulding compounds

Typisches Anlagenlayout für die Herstellung von EP-Masse

COMPEO compounder for thermoset compounding

Take a look at our typical plant layout for the production of thermosets in our COMPEO showroom.

Get to know our Co-Kneader series

BUSS Co-Kneaders

worldwide

Our patented Co-Kneaders are used worldwide nowadays, supporting our customers in the production of plastics. Using the BUSS compounding systems, our customers can master all the demanding requirements for thermoset compounding.

World map with an overview of the Co-Kneaders used for thermoset compounding

Number of Co-Kneaders used for thermoset compounding

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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.

Epoxy resin molding compounds

Epoxy molding compounds have been known for their good electrical and mechanical properties as well as their excellent chemical and aging resistance for a long time.

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.