A water-based adhesive with polar recognition both for TPO substrate and WPU coating

Abstract

Thermoplastic polyolefin (TPO) is widely used in automotive interior materials, but it has long been faced with the challenge of weak adhesion between water-based polyurethane (WPU) coating and substrate. Herein, chlorinated polypropylene (CPP) was grafted by styrene (St) firstly, then a water-based CPP adhesives with polar recognition both for non-polar TPO substrate and polar WPU coating were prepared via phase conversion methods, and the adhesives properties as well as the adhesive mechanism for different polar substrates were investigated. The introduction of polystyrene side-chain has improved the recognition ability of CPP adhesive to non-polar TPO substrate and the interaction force between interfaces. Compared with unmodified CPP adhesive, T-peeling strength of modified one has increased by 35 % and reached 24.2 N/cm, meeting the adhesive requirements of TPO as an automobile interior material. Adhesive mechanism study reveals that polar mutual recognition CPP adhesive plays a bridging role, one end recognizes the non-polar TPO substrate and another end recognizes the polar WPU surface coating, and forms a strong bond between the guest and the host through their respective interfacial force.