Polyolefin layer with improved adhesion to a foamed plastic substrate and a method for its manufacture

A rotational molding process for manufacturing objects having a foamed plastic substrate adhered to a polyolefin coating layer, and having improved adhesion therebetween comprising the combination of steps of:

• (a) preparing a first outer coating layer of a stabilized polyolefin by rotational molding wherein a stabilized powdered polyolefin is introduced into a heated rotational mold and during said rotational molding said mold is heated to a temperature above the melting point of said stabilized polyolefin;
• (b) forming a second inner layer of an at most slightly stabilized polyolefin contiguous with and on the interior surface of said first outer layer by rotational molding wherein an at most slightly stabilized powdered polyolefin is introduced into said rotational mold subsequent to the formation of said first outer coating layer of the stabilized polyolefin while said mold is heated;
• and thereafter
• (c) introducing a foamable plastic material onto the interior surface of the thus formed second layer in said mold and foaming said plastic thereagainst whereby the foamed plastic is bonded to said interior surface.