Synthetic leathers often comprise a textile base onto which a polymer layer is applied, typically consisting of an adhesive and an embossed top layer. Interestingly, the textile backing and the top coat usually contain entirely different materials. These textiles can be woven, knitted, or nonwoven fabrics made from PET, PET/cotton, or polyamide, while PVC and various polyurethanes are common choices for coatings. However, using such composite materials falls short of meeting today’s sustainability standards, as they are costly or impossible to recycle by type and are not biodegradable. This has sparked an urgent search for alternative materials.
In response to this need, the EU's Sustainable Products Initiative (SPI), part of the “Green Deal” adopted in 2022, introduced an eco-design regulation emphasizing a product’s life cycle and resource conservation. For textile and product design, this entails integrating concepts like closing the loop or considering end-of-life scenarios during product development.
An AiF project, conducted collaboratively by the DITF and the Freiberg Institute gGmbH (FILK), has yielded a breakthrough: the development of synthetic leather in which both the fiber material and the coating polymer are identical, a crucial step for an industrial recycling concept.
The aliphatic polyester polybutylene succinate (PBS) was identified as the base material due to its favorable properties. PBS can be sourced from biogenic materials and is readily available in various grades and quantities. Its biodegradability has been demonstrated in tests, and its thermoplastic nature facilitates processing and subsequent product recycling.
To achieve this, adjustments were made in the cooling shaft at the DITF to optimize the primary spinning process and produce PBS filaments with desirable textile mechanical properties. This successfully spun POY yarns at high speeds, boasting excellent tenacity. These yarns were then easily processed into pure PBS fabrics, serving as the textile base substrate for subsequent extrusion coating, where PBS was also employed as a thermoplastic.
Through streamlined production steps, PBS composite materials with the typical structure of artificial leather were successfully produced. Their purity and biodegradability meet the criteria for a closed recycling process, marking a significant advancement in sustainable material innovation.
