Extrusion and Processing of TPE in Pipe & Tube

With electric vehicles, the demand is for light weight, recyclable tube constructions. The transition is taking place as we help customers shift from rubber compounds to thermoplastic elastomers.

Natural rubber or EPDM is traditionally used by pipe & tube manufacturers in applications like automotive and medical. However, new regulations and sustainability initiatives are convincing producers to replace their conventional materials with thermoplastic elastomers (TPE).

Driving the move

The shift in market demands is essentially driven by two factors. First, there is regulatory compliance. TPE helps manufacturers comply to increasingly stringent regulations regarding the use of hazardous substances in consumer products, wherever REACH and RoHS directives apply. Second, is the ability to recycle. Thermoplastic elastomers are easier to process for reuse, and so can advantageously replace the thermoset counterparts.

In the emerging field of electric vehicles, the constraints are changing compared to traditional multilayer constructions. Since operating temperatures under the car hood (bonnet) are lower, new solutions are envisaged. New product design possibilities open up to manufacturers. They include the ability of varying the hardness, contributing to noise attenuation, or replacing corrugated pipes in some applications. What’s to gain? The significant gains mentioned when switching to TPE are:

• Weight reduction (up to 20%)
• Faster processing overall
• Cost-effectiveness by eliminating autoclave crosslinking
• Energy efficiency

TPE can also be used as a replacement for other polymers such as plasticized PVC (p-PVC), since it is considered a safer and more environmentally friendly alternative. This makes TPE particularly suitable for applications in healthcare, electrical devices, and transportation, amongst others.

A diverse family

As a substitute for thermoset elastomers, TPE may share rubberlike features but is of different origin. They are made of monomer bases that make them close cousins to polystyrenes, polyurethanes, polyolefins, polyamides or polyesters, for example. The diversity in the TPE family is recognizable when listing the individual initials such as SEBS (TPS), TPU, TPV or TPE and TPC-ET. The variety of TPE types allows for customization to meet specific industry requirements, such as hardness, elasticity, resistance to environmental factors and wear resistance. Maillefer proposes extrusion systems to meet the specific TPE requirements for medical tubing, seals, automotive (flexible) pipes and flexible cables.

Leveraging know-how

TPE is not new, yet its usage is clearly expanding. Maillefer has accompanied the developments in extrusion of elastomeric thermoplastics. The material expresses very different rheological behaviors during the plasticizing and forming processes. Consequently, our machines have been specially optimized. We consider the differences in composition and properties of different resins by adapting our extrusion screw geometries, as well as the extrusion and calibration tools.

Know-how in manufacturing with TPE gets leveraging from our experience and expertise in a variety of related applications such as medical tubes (IV tubing), industrial tubes, and automotive tubes. Our powerful line control system reflects the know-how acquired and ensures the repeatability and reproducibility of the application processes.

Complete solution

Our extrusion lines for TPE processing are complete and fully integrate all components. The elements are perfectly synchronized, with all the equipment installed, including a vacuum calibration trough with digital flow meters, diameter controllers, thickness gauges, yarn reinforcement machines (e.g. knitting, spiralizing, braiding), pre-heaters, vacuum pumps, cutters, winders, etc.

The powerful Nomos PSU version 6 controls the line with precision and offers several features. The thorough tracking tool can store an unlimited number of parameters. The data is easily accessible for extensive offline analysis. A complete system results in high level performance as recommended when processing materials with highly elastic properties.

Yves Zweifel, PhD
R&D Manager
yves.zweifel@maillefer.net