Method for the fabrication of synthetic-material component assemblies

#The invention relates to a method for the fabrication of synthetic-material component assemblies having components which are formed by blow-molding and are preferably coated with a decorative material at parts of their surface.

#In order to achieve a visually and tactilely attractive surface, components fabricated from synthetic material by the process of blow-molding are coated with a decorative material which is backed in addition with a layer of foamed material in order to improve the tactile qualities, for example through the use of a soft, flexible yielding surface.

#Normally, the components are fabricated in a first process step from an extruded synthetic-material tube by the extrusion blow-molding process. Components formed in that way are known to possess a high rigidity and it is possible during the blow-molding process to mold on diverse functional elements such as air channels, mechanical guides, devices for fixing, pockets and the like, at the same time.

#FIG. 1 is a fragmentary, diagrammatic, cross-sectional view of a double-walled component fabricated by a blow-molding process with a surface decoration backed with foamed material attached to part of its surface; and

#FIG. 2 is a fragmentary, cross-sectional view of a double-walled component according to FIG. 1, but with a second layer of foamed material between an outer surface of the blow-molded part (component) and decorative material.

#Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, it is seen that part of a surface of a double-walled component or blow-molded part 1 of synthetic material is coated with a decorative material 3 which is backed by a layer 2 of foamed material. Whereas the decorative material 3 is disposed purely for purposes of appearance, the layer 2 of foamed material serves to improve tactile qualities in the region of the part of the surface which is coated. In order to achieve an exactly bounded transitional region between the coated part of the surface and the uncoated surface of the component or blow-molded part 1, a decorative groove 5 is formed in the component or blow-molded part 1 in the region of an edge of the decorative material 3. A bent-over edge of the decorative material 3 including the backing or layer of foamed material 2 are enclosed in the decorative groove 5. The decorative material 3 and the backing of foamed material 2 jointly form a decorative element 6. In the particular embodiment according to FIG. 1, the component 1 is formed of polypropylene, the decorative material 3 is polypropylene textile, and extruded polypropylene foam (X-PP) is used for the layer of foamed material 2. A component which is formed in this way on the basis of polypropylene meets the aesthetic and tactile requirements that have been set and is also outstandingly suitable for later recycling.

#In the embodiment shown in FIG. 2, the tactile qualities of the coated part of the surface of the component 1 are improved further through the use of first and second layers 2 and 4 of foamed material. In this case the second layer 4 of foamed material is formed of expanded polypropylene (E-PP).

#The fabrication of components in the various above-described embodiments is carried out in such a way that initially an extruded and/or expanded polypropylene foam is heated at the surface to a temperature in the melting range of this material and is pressed and bonded at the molten surface with the decorative material of polypropylene textile to a composite decorative element 6 and preformed to a final contour of the component 1. During pressing, the molten polypropylene foam penetrates the surface of the decorative material and bonds firmly with it. Next, the preformed composite decorative element of foamed material and decorative material is inserted in a blow-molding die and held therein by fixing pins or a reduced pressure generated at an inner surface of the mold in the region of the composite decorative element 6.