Roboust adhesive bonding of vaccum formed polyporpylene

Important results from the project

PP materials are inexpensive, but often difficult to bond with adhesive. Flame and corona treatment can be good enough for paint adhesion but is not always sufficient for bonding. The aim was to develop a robust and quality-proof pretreatment with plasma for vacuum formed PP, evaluate how it differs from today´s pretreatment processes and evaluate quality inspection methods prior to bonding. The results with plasma show that it is possible to receive a fully good adhesion to such extent that the adhesive can be trusted as the weakest point and not the adhesion between adhesive and surface.

Expected long term effects

The results show that plasma treatment can secure adhesion of adhesives to the substrates. The change from adhesive to cohesive failure means that it is possible to utilize the full mechanical potential of the adhesive with plasma. Corona also improves the bonding compared with an untreated surface but causes a lot of adhesive failure. Flaming also improves the bonding but less than corona. The quality inspection methods had a clear difficulty in identifying the contaminations on the surface. The dissemination of results from the project was performed in articles and an open workshop.

Approach and implementation

The project was performed as collaboration where all parties have been active in the planning, test preparation, discussion and analysis. Manufacturing of materials, corona and flame treatment was carried out by Andrénplast in existing production equipment. Gleitmo was evaluated all shear testing and Swerea IVF was performing the plasma treatment, peel testing, accelerated aging and quality inspection methods. Two robotic plasma devices and several plasma parameters were evaluated as well as effects of multiple treatment and time between treatment and bonding.