Self-healing coating surfaces – more component performance and design freedom
Published on : Thursday 16-09-2021
Good adhesion between polycarbonate and PU-RIM coating even during aging; new methods for simulation of paint filling and component distortion.
September 2021 – DirectCoating (DC) with polyurethane (PU) coating systems is a new process for producing functionally highly integrated and nobly decorated plastic parts economically and sustainably. Rühl Puromer GmbH and Covestro have joined forces to expand the technology's suitability for large-scale production.
"We want to open up the process for broad use in electromobility and autonomous driving applications and use it, for example, to manufacture large-area decorative parts with multifunctional, seamlessly integrated display, operating and ambient lighting elements for car interiors," explains Dr. Olaf Zöllner, head of application development Europe in Covestro's Engineering Plastics business entity.
"We also see good opportunities in highly integrated passenger car exterior parts such as spoilers, radar covers, front fascias and pillar trim with touch panels for vehicle access. There is also great potential in medical, communications and IT technology," adds Dr Ingo Kleba, managing director at Rühl Puromer.
The DC process combines two established technologies in one process: injection moulding of thermoplastics and reaction injection moulding (RIM) of PU systems. First, a thermoplastic carrier is produced in a mould cavity and then transferred to a second cavity, which is enlarged by the thickness of the coating layer. There, the PU system is then injected onto the carrier.
The PU coatings offer unusually great freedom in design. The surface of the component can be made transparent, translucent or coloured through, and it can be made highly resistant to chemical media such as fatty skin creams or given leather-like soft-touch haptics. Filigree surface structures can be precisely moulded. High-gloss areas can be directly adjacent to matte structures. In addition, there is no need to invest in separate painting systems. Compared with spray painting, there is no paint loss due to overspray, and there is less scrap due to painting errors.