The present invention relates to an article made of plastic material, which article at least partly includes a laminate which comprises a layer of expanded plastic material, and the process for manufacturing such an article.
Articles made of plastic material with a heat insulating ability have been commonly known for a long time. One example of such an article are containers made of expanded thermoplastic styrene, so-called styro-foam containers. These containers are excellent as heat insulators but have a very poor mechanical stability which will give them the characteristics of a disposable package. The surface of these containers is furthermore porous, which will make them rather difficult to keep clean. They are therefore less suited for use in the food supply industry.
Another type of articles made of plastic material is the rotation moulded plastic pallet. Initially a skin of solid thermoplastic material such as polyethylene or polypropylene is manufactured. The skin is after cooling filled with an expanded thermosetting polymer, most often polyurethane. Surf boards are also manufactured by this procedure. The reason for the use of expanded polymer is not the insulating effect in these cases, but the stabilising effect that will be obtained.
Yet another type of articles made of plastic material, are manufactured by blow moulding. These can be made twin-walled with an intermediate hollow space. Compost receptacles can be mentioned as an example of such articles. The hollow space can be filled with an expanded polymer if an increased heat insulating ability is desired. Normally a thermosetting material of polyurethane will be used.