Abstract: An elongate packing is sandwiched between two sheet-like mold members in an encircling manner to define a mold cavity therebetween, then a thermosetting plastic material is poured into the mold cavity, and the thermosetting plastic material is heated and set in the mold cavity. The upper and lower mold members are held against deformation transverse thereof so as not to be deformed by the shrinkage of the thermosetting plastic material when the latter is set, and the packing is allowed to move transversely thereof for following the shrinkage of the thermosetting plastic material when the latter is set. In some embodiments, the packing comprises a packing body adapted to be sandwiched between the mold members for preventing the plastic material from flowing out of the mold cavity with a flange joined to the packing body and adapted to be held against peripheral edges of the mold members.

Abstract: A multilayer compression-molded article produced by compression-molding a composite plastic material. The composite plastic material comprises a first synthetic resin and a second synthetic resin in which the first synthetic resin surrounds substantially the entire second synthetic resin. The compression-molded article comprises a first resin layer molded from the first synthetic resin and a second resin layer molded from the second synthetic resin in which the first resin layer surrounds substantially the entire second resin layer. The composite plastic material is obtained by an extrusion apparatus which intermittently extrudes the second synthetic resin via a subsidiary extrusion flow passage into a main extrusion flow passage in which the first synthetic resin flows.