Process for the manufacturing of an article of plastic material

A process for the manufacturing of a hollow article made of plastic comprising a solid outer layer with an intermediate expanded layer and a functional part selected from the group consisting of reinforcing profiles, guiding profiles, stacking profiles, hinge parts, pockets, label holders and profiles for automatic handling and locking, the process comprising:

• extruding a first thermoplastic material into a sheet or tube shaped work piece forming a first layer;
• adding further molten first thermoplastic material, molten second thermoplastic material and an expanding agent to the work piece by extrusion to form a laminate comprising a first and a second layer of solid first thermoplastic material and an intermediate layer of an expanded second thermoplastic material with an average density of 50-800 kg/m3 which together forms the tube or sheet shaped workpiece;
• shaping the workpiece by at least one method selected from the group consisting of vacuum forming and blow molding in a mold having a mold cavity with special cavities which cavities are negative depictions of the functional part, by means of at least one selected from the group consisting of gas pressure and vacuum;
• filling the special cavities with a molten third thermoplastic material to form the functional part;
• and
• integrating the functional part with the remainder of the article.