Two part composite plastic component manufacture

摘要

A second injection stage uses a foamable thermoplastic or thermoplastic mixture comprising two or more plastics and the tool is opened after injection to allow the plastic to foam completely. Independent claims are included for: (a) use of the process in the manufacture of sound deadening covers, especially the undersides of vehicle instrument panels; (b) a composite plastic component comprising two parts (6, 10). In (b), the first part (6) is injection molded in a thermoplastic, especially polypropylene (PP) or acrylonitrile-butadiene-styrene (ABS) copolymer, and the foamed second part (10) can be an open or closed cell flexible foam and may have a skinned surface. The foam composition can be a single or multi-component system. Foaming is initiated either by heat, pressure relaxation or irradiation, especially with microwaves. The sealing edge of the second part can be straight or irregular, e.g. a zigzag.