Thermoplastic foam injection moulding for recyclable 2K soft-touch visible parts
Soft-touch components have become established in numerous applications and are now indispensable in areas such as automotive interiors and sports equipment. However, these components typically comprise multiple materials that are inseparably bonded and thus non-recyclable. In particular, the automotive sector faces growing scrutiny due to the European Commission’s efforts to regulate end-of-life vehicles (ELV directive).
Consequently, the Foam2Cycle project, aims to develop an alternative manufacturing technology. This approach will enable compliance with forthcoming legislative requirements on recyclate content, even for soft-touch and visible components, while facilitating more sustainable products. Central to this endeavour is the integrated development of both material and process technology. In place of conventional soft-touch materials such as PUR and PVC, thermoplastic elastomers will be employed for the soft component, offering material recyclability in contrast to PUR. Polypropylene will serve as the carrier material, yielding a quasi-monomaterial composite.
The material is to be processed in a two-component foam injection‑moulding process to produce the soft‑touch component. The process variant developed at IKV uses chemical blowing agents for foaming. The injection mould used is designed as a breathing mould, i.e. unlike in conventional thermoplastic foam injection moulding, the cavity volume varies over the course of the cycle (Fig. 1). Following complete cavity filling, a brief holding pressure phase is applied to ensure precise, defect-free replication of the cavity surface. The cavity volume is then increased, prompting the internal material to foam. The degree of foaming can be precisely controlled via the mould opening stroke and determines the resulting foam haptics.
Foaming can reduce the density of the carrier by around 8% and that of the TPE by up to 80%. After shredding, the two thermoplastic components can be mechanically recycled together. As the concept uses established materials and processes, it provides a basis for transfer to industrial production. The inline inspection system integrated into the exhibition-stand production cell demonstrates how selected component properties can be monitored during production.
© IKVProject data and funding
We would like to thank the BMWE for funding the project as part of the Central Innovation Program for SMEs (ZIM, funding code KK5158711) and the project partners for their cooperation.
Project duration: 01.06.2025 – 31.05.2027
