Abstract: The temperature of the molten mixture within a multi-screw extruder is maintained in the range of from the melting point of the macromolecular material up to 20.degree. C above said melting point, by an extruder having at least 2 screws, said extruder being constructed such that the ratio (H/D) of the diameter (D) of the screws to the interlocking depth (H) of the screws is equal to or less than 0.1 and the flow of the mixture of inorganic additive and macromolecular material within the screws can be so controlled that the difference in residence time of more than 90% of said mixture is no more than .+-.10% relative to the prescribed residence time, whereby the dispersion of said inorganic additive is extremely improved.

Abstract: A method for producing plastic compound comprises pressure-feeding a resin and an additive therefor into a barrel, and applying compressive force and shearing force on the resin and the additive in the barrel at a predetermined temperature in such a manner that the position of the minimum clearance defined between a bore of the barrel and the maximally diametered portion of a rotor continuously changes with respect to the whole circumferences of the barrel and the rotor, whereby the resin and the additive are uniformly kneaded.