Kraiburg TPE: Circular economy for thermoplastic elastomers

Waldkraiburg, Germany - The principles of the circular economy are becoming increasingly important in the polymer industry. The aim is to use resources efficiently, avoid waste, close material cycles, and design products to be sustainable throughout their entire life cycle.

Thermoplastic elastomers (TPE) play a special role in this context – they combine the flexibility of elastomers with the thermoplastic processability of plastics, thereby opening a wide range of approaches to conserving resources.

As an overarching goal,'Design for sustainability' encompasses extending the lifecycle of an application and using alternative raw materials, as well as design for recycling and for circularity at the end of a product’s use phase.

Minimising impacts on people and the environment throughout the entire product lifecycle also plays a central role.

Choosing the right TPE for a specific component and the quality of the material are crucial for the longevity of a product.

Since there is a wide range of different qualities and types of TPE on the market, it is essential to work with an experienced and customer-oriented supplier and to discuss requirements and material selection right from the start of the project.

Alternative materials

To reduce the consumption of fossil resources, TPEs with recycled or bio-based components are increasingly being developed and offered.

Recycled content TPEs can be based on post-industrial (PIR) and post-consumer (PCR) waste streams. In addition, many companies now also offer mass-balanced materials.

This makes it possible to contribute to the demand for alternative raw materials while maintaining material approvals and compliance.

Especially in strictly regulated markets such as direct food contact or medical, this offers an opportunity to gradually reduce the use of fossil raw materials.

Product design

'Design for recycling' begins with product design. The aim here is to consider the entire life cycle of a component, including the fact if it can be efficiently recycled and if the resulting recycled material can be used as a secondary raw material.

Numerous studies have been conducted on the influence on technical performance and corresponding addition recommendations for the ongoing process.

But what happens to TPE at the end of a product's life?

Pure TPE can be remelted and reprocessed at any time. This means that these materials are very well suited for recycling. #

However, since TPE is usually used in smaller quantities than plastics such as polypropylene (PP) or polyethylene (PE), there are no established recycling streams for this material class.

Suppliers must, therefore, develop their own strategies to exploit the recycling potential of TPE.

Waste streams & marketability

Since thermoplastic elastomers are often used in combination with polypropylene -for example, in packaging seals or in direct food contact applications - Kraiburg TPE initiated a research project in collaboration with the cyclos-HTP Institute.

The aim was to test the recycling compatibility of selected TPS materials (thermoplastic elastomers based on styrene block copolymers) in polyolefin streams. In addition, the potential effects on the quality of the post-consumer recyclate were investigated.

The investigations show that numerous TPS types of Kraiburg TPE are co-recyclable in the established PP- or HDPE-plastics waste stream. This means that they can be recycled together with these materials.

This is an important finding because, as mentioned above, TPEs have not yet been assigned to a dedicated recycling stream.

Closing the loop

The studies conducted with the cyclos-HTP institute support the verification of the compatibility of many Kraiburg TPE TPS compounds in established recycling streams and thus assist component manufacturers in evaluating their products.

However, there are additional approaches to effectively closing TPE cycles – this requires the initiative and commitment of TPE manufacturers.

Kraiburg TPE has been working on its ‘Loop TPE’ project for some time now. Customers can, for example, send sprue waste to the company for reprocessing.

This waste is tested, shredded, and completely reprocessed into a new recycling-based TPE for the respective application. This means that high-quality scrap materials are repurposed in a meaningful way and waste is reduced.

At the same time, the use of primary raw materials declines and cycles are closed, even though there are no established recycling streams for TPE yet.