A New In-Mould Decoration Process using Real Wood Veneer

Abstract

The use of real wood by manufacturers in automotive interiors is seen as a mark of a premium car quality. The current manufacture of aesthetic veneered components is both costly, resource demanding and time consuming. An alternative in-mould decoration manufacturing method is considered here, using back injection moulding of wood veneer onto plastic components. Two common polymer materials, polypropylene, (PP) and acrylonitrile, butadiene, styrene, (ABS) are used with four different types of wood veneer in a simple geometry plate mould. It was found that all these samples moulded satisfactorily and good adhesion was achieved. Shrinkage values of the mouldings are presented. Boil tests resulted in adhesion failure for all the ABS samples whilst the PP samples remained adhered to the wood laminate. This was found to be due to the rheology of the polymers and the resultant level of melt penetration, which was measured using optical microscopy. Scanning Electron Microscopy, (SEM) revealed that a high level of interaction is present at the interface with parts made from PP. The PP was found to penetrated voids and opening in the veneer and even travel into resin ducts. This was true throughout the range of veneer types. This high level of interaction has increased the surface area of the interface thereby securing a mechanical interlock condition. PP's of this MFI or higher would be suitable for this injection moulded application based on the findings to date. On the other hand parts made from ABS had a very poor level interaction present with voids evident at the interface in the order of 25 μm. The poor level of interaction has resulted in a low contact surface are resulting in the failure to the test regime.