SKZ and Fraunhofer IFAM
Improving the surface quality of recycled components by means of plasma coating

08.11.2022 In a joint research project, the German Plastics Center SKZ in Würzburg and Fraunhofer IFAM are investigating the possibilities for improving the surface properties of recycled plastics with regard to adhesive applications. Activation and coating processes with atmospheric pressure plasma serve as the means of choice for this.

Surface activation with static atmospheric pressure plasma.
© Photo: SKZ
Surface activation with static atmospheric pressure plasma.

Plastic components made of recycled material or with a defined recycled content often exhibit considerable fluctuations in their material composition due to the material and process, which leads to inhomogeneous and fluctuating surface properties. Reasons for this are a varying molecular weight distribution of the recycled plastic, the loss of stabilisers and other functional additives as well as the possible contamination with foreign material.

Adhesion-friendly surface qualities required

Consequently, process steps downstream of reprocessing and forming - for example, bonding, painting, printing and coating - are prevented or made more difficult because they are based on defined and consistently adhesion-friendly surface qualities.

The aim of this project is to favour the use of recycled materials for surface-specific processing steps by adapting the surface properties. This is to be achieved by atmospheric pressure plasma pretreatment processes and deposition of an adhesion-promoting layer by means of plasma polymerisation (PECVD - Plasma Enhanced Chemical Vapour Deposition). In this process, the surface variance of the recyclate surfaces is levelled out so that an increase in adhesion for subsequent bonding is achieved. In addition, a migration barrier for additives from the recyclates is possible. Interested companies are welcome to contact the SKZ with specific questions and suggestions.

Project 22619 N of the research association FSKZ e.V. is funded by the Federal Ministry of Economics and Climate Protection (BMWK) via the German Federation of Industrial Research Associations (AiF) as part of the programme for the promotion of joint industrial research (IGF) based on a resolution of the German Bundestag.