Application

PVC cable compounds

PVC has been used for cable insulation since 1932 – originally as a replacement for rubber

Depending on the requirements profile, different plastics are used for manufacturing cable sheathing with BUSS compounding systems. These include polyolefins, TPE, PPE, EEFE, PVA and naturally flexible PVC cable compounds. The use of PVC as cable sheathing has been known since 1932 and was originally used as a substitution product for rubber.

Typical areas of application

Grey PVC cable compound granules produced with the BUSS compounding systems
Beige PVC cable compounds granules for cable insulation
Turquoise flexible PVC cable compound granules from a BUSS compounder
Cable end with different cable insulation layers which show the PVC cable compound options

Due to the relatively high dielectric resistance, which leads to corresponding losses and heating in the alternating current field, soft PVC compounds are used up to a voltage of 10 kV. They account for the majority of applications in this field. By adjusting the formulations, the application temperature, the mechanical properties such as flexibility in the application, flammability and processing can be customised.

Here are two examples:

  • By adjusting the type of plasticiser, the continuous application temperature can be increased up to 105°C.
  • With the addition of aluminium trihydroxide, the flame resistance and smoke formation can be improved in a targeted manner. The regulators such as VDE, EN or UL specify standardised property profiles for insulation and sheathing compounds.

The main areas of application are power transmission up to the 10 kV mentioned above, domestic installations, especially in the private sector, and data transfer in general. In the automotive industry, soft PVC cable compounds are used almost exclusively.

Further insights into our options for cable applications

Benefits

BUSS compounding technology offers the following specific benefits

Mixing in the Co-Kneader is independent of the pressure build-up in the downstream discharge unit, allowing an individual optimization of both process steps. This allows processing at low pressure and temperatures as well as optimum pelletizing, whilst temperature control remains guaranteed at all times.

The processing of a wide range of formulations with the same screw configuration can be a challenge. The BUSS Co-Kneader technology is meanwhile known for this specific capability, thanks to a processing length which normally is only half as long as for comparable systems, moderate and adaptable shearing rates and greater flexibility in screw configuration design.

BUSS multi-flight compounders achieve an intense mixing effect with a lower 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 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.

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 striations with 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.

Compounding requirements

of PVC cable compounds

The preparation of the PVC cable compounds takes place exclusively in 2 stages: via a hot/cold mixing process in the powder phase with following compounding and pelletizing on the BUSS Co-Kneader.

The compounding requirements can be described as follows: The plasticizer content absorbed in the porous PVC grain and the further formulation components such as stabilizers, additives, fillers and reinforcing agents, flame-retardants, etc. must be specifically gelled, dispersed and distributively mixed and broken down. Well-defined temperature limits must be observed.

The customized property profiles result in wide-scale diversity of formulations with rather decreasing batch sizes which are produced efficiently.

The BUSS Co-Kneader can exploit its performance strengths with uniform, moderate and, if required, adjustable shear rates. The free volumes are designed and realised along the process axis according to the requirements. In most cases, it is possible to produce the entire range using universal shaft geometry designed for the formulation portfolio.

The modularity of the entire system (shaft geometry, installations, shaping options, etc.) also enables adaptation to changing requirements at all times. This provides a top level of investment security.

Low specific energies with the most intense mixing processes, volumetric scale-up processes and the highest availability due to the large operating range emphasize the fact that the BUSS Co-Kneader is and remains first choice for compounding insulation mass from PVC cable compounds.

Typical plant layout

Typical plant layout for the production of PVC compounds

Get to know our COMPEO compounder series

BUSS Co-Kneaders

worldwide

Our patented BUSS 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 manufacturing PVC cable compounds.

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

Number of Co-Kneaders used for manufacturing cable compounds

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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.

HFFR cable compounds

Polyolefins have excellent insulation properties, but are also highly flammable and must be made flame-retardant accordingly.

Soft PVC

During the first half of the 19th century, the creation of PVC from vinyl chloride (VC) was first described. By the time the Second World War ended, it was already the most-produced plastic. Today, industries such as medical technology rely on the unique properties of PVC-P.