Abstract: Multiple layered plastic sheets is produced by sequentially disposing at least two powdered flowable materials onto a melted layer of plastic being conveyed in a given direction. Each material corresponds to a separate layer of the resulting multilayer sheet.

Abstract: An injection molding apparatus including a barrel for holding molten plastic material, a first passage connected at one end with the barrel for receiving hot plastic material from the barrel, a second passage connected with the other end of the first passage for receiving molten material from the first passage for supplying the material to a mold, a cylinder, a third passage connected at one end with the cylinder and connected at its other end with the second passage, a piston in the cylinder, movable by pressure means in one direction to maintain pressure on molten material in the cylinder, the third passage and the second passage, and movable by pressure means in the other direction to exert a suction action in the cylinder, the third passage and the second passage for drawing molten material in the second passage back into the third passage and the cylinder, and a valve means.

Abstract: An apparatus for making hollow articles having a rotatable polygonal turntable, a parison forming station at one side face of the turntable, a blow molding station at another side face of the turntable and a stripping station at still another side face of the turntable. The apparatus has means for connecting at least one core rod on which the parison is formed to the turntable, such that at least one core rod is parallel to a side face of the turntable, and for rotation therewith.

Abstract: Heat treatment of a material, e.g. a finely divided resin, wherein the material is introduced into a drum and agitated by rotating, spaced blades which whirl the material into a dispersion. The action of the blades heats the resin particles so that heat for the heat treatment is provided. The heat treatment can be, e.g. to cause small resin particles to coalesce with larger particles in the processing of polyethylene reactor flake, to improve flowability of the resin, or to admix resin and additive. To obtain increased capacity while the size of the apparatus is maintained within reasonable limits, two intersecting, generally cylindrical drums, each outfitted with an agitator, are used. Apparently the dispersions of the respective agitators slam into each other in the vicinity of the intersection causing additional heating.