Decorative skin

Brightly coloured, light-stable decorative skins made of polyurethane can now be produced directly in a Reaction Injection Moulding (RIM) process as a result of a partnership between Bayer MaterialScience and Faurecia.

Working together, they have developed an aliphatic polyurethane production process that enables a decorative skin to be produced in a pre-production mould.

'The (new) solution is a cost-effective alternative to both polyurethane spray-on skin technology and in-mould coating RIM technology. We envisage a huge potential for the technique, particularly with decorative skins for components in automotive and commercial vehicle interiors, such as instrument panels, arm rests, centre consoles, and door trims,' said Bayer MaterialScience's Gregor Murlowski.

The aliphatic RIM skin is produced in a one-step process, making it a more cost-effective solution than the in-mould coating (IMC) RIM process, in which a decorative coating is first sprayed into the mould before aromatic polyurethane is injected in a second step.

Although polyurethane skins produced in this way offer a high level of quality, the disadvantages of the two-stage process – such as longer cycle times and higher investments for moulds and equipment – must be taken into account.

The other previous production alternative - spraying on a skin of polyurethane in an open mould - can also lead to unwanted material build-up, which causes irregular features on the surface.

'By contrast, the advantage of the RIM process is that it enables wall thickness to be produced very accurately, even in places where a spray head cannot be positioned precisely, which prevents material build-up,' explained Murlowski. A further benefit of this RIM process is its cost-effectiveness. 'Depending on the component being manufactured, we anticipate that the process will be up to 50 percent faster than polyurethane spray-on skin technology,' he added.

The light-stable Bayflex LS (Light Stable) is the polyurethane material used in this new process.