Abstract: A process for producing polylactic acid includes the steps of polycondensing lactic acid to a lactic acid prepolymer having a weight-average molecular weight of 10,000-50,000 in a batch-type polymerization reactor, and polycondensing the lactic acid prepolymer to lactic acid polymer having a weight-average molecular weight of at least 100,000 by means of a screw-type extruder.

Abstract: A method of reclaiming a plastic product having a paint film, including the steps of: obtaining crushed particles by crushing a plastic product having a paint film into particles of a predetermined size; supplying the crushed particles to a screw-type extruder; kneading and fusing the crushed particles while supplying water thereto; and obtaining a plastic by discharging a gas produced by decomposing the paint film and vaporized water.

Abstract: A method of producing fiber reinforced plastic moldings.

Abstract: A method of forming a composite material involves feeding materials to a kneader, kneading the materials, and injecting them from the kneader into a mold. The kneader is formed by a screw-type extruder having an ejection outlet at one end for extrusion into the mold. Various input ports are located axially along the extruder. Materials are fed into the kneader beginning at the inlet port most remote from the outlet end and proceeding successively to the inlet port nearest the outlet end. The materials are fed in successive order from those with the highest viscosity and lowest reactivity relative to the materials with the highest reactivity and lowest viscosity. For example, thermoplastic is fed to the inlet most remote from the outlet, and thermosetting resin is fed to the inlet nearest the outlet. In another aspect of the invention, in which thermoplastic and thermosetting resins are employed in roughly comparable amounts, an "island-in-sea" structure is desired.

Abstract: Synthetic macro-molecule materials are continuously supplied into the cylinder of an extruder so that said synthetic macro-molecule materials are internally heated by the shearing as well as kneading action of the screw to which they are subjected and externally heated by the heat transmitted through the wall of the cylinder of said extruder from an outside heat source so that said synthetic macro-molecule materials are continuously thermally decomposed within said cylinder, thereby vapourized thermally decomposed products are fed to the condensing means through one or more discharge orifices provided in said cylinder to be recovered there as thermally decomposed products having low molecular weights.