Rotational moulding method and apparatus for making multi color plastic articles

Rotational moulding method and apparatus for making multi color plastic articles

An improved rotational molding apparatus and method are provided for rotational molding of plastic articles having differently colored sections. The method and apparatus use a rotational mold having first and second mold shells separated by a removable partition member to form first and second interior spaces within the mold. A thin blade is held against the inner surface of at least one of the mold shells to define a plurality of compartments within the respective interior spaces. Differently colored molding materials, preferably plastic powders, are introduced into each of the compartments and caused to melt against the inner surfaces of the mold shells. The surfaces of the blade and the partition member are kept at a lower temperature than the inner surfaces of the mold shells to prevent the molding materials from melting against the surfaces of the blade and the partition member. The partition member and blade are then removed by separating the first and second mold shells, and additional non-colored, plastic powder is added to the mold. The rotational mold is then closed, heated and rotated to cause the plastic powder to melt against the colored plastic powders on the inner surfaces of the mold shells. The result is a rotationally molded plastic article having controlled placement of differently colored molding materials and a nearly seamless interface between the differently colored sections.