Extruder for producing molten plastic materials
First Claim
1. An extruder comprising:
- an elongated barrel centered on a barrel axis and having a polycondensation region;
an extruder screw extending axially in the barrel through the region and having an outer surface;
a guide in the barrel;
a plurality of shaft screws extending along and rotatable in the region about respective shaft-screw axes parallel to the barrel axis, partially surrounded by the guide, having axially opposite ends, and having outer surfaces spaced from the guide and from the outer surface of the extruder screw by a distance at least equal to 0;
means for rotating the shaft screws about the respective shaft-screw axes.
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Accused Products
Abstract
The invention concerns an extruder for producing molted plastic materials from plastic granules available on the market, by heating and mixing granules, with heated single- or double-screw extruders, and for carrying out polycondensation or polymerization using part of a multiple-screw extruder and by means of vacuum chambers for removing the constituents of low molecular weight and/or foaming agents or the like, for obtaining larger molecules and hence a higher viscosity, and for increasing the mechanical strength of plastic materials produced from said molten material. The invention aims at designing said extruder such that the molten material can be processed in thin layers enabling exposure of large surfaces in contact with the vacuum, and hence a molten plastic material ensuring desired levels of degassing and polymerization using simple means. Therefor, the envelopes of the stems of the screws (7) are mutually spaced apart at least in the polycondensation zone of said extruder part with multiple screws (6), relative to the extruder screw (4) or its shaft section (10) and relative to cylindrical zones enclosing them, by a distance not less than zero (≧0).
58 Citations
20 Claims
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1. An extruder comprising:
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an elongated barrel centered on a barrel axis and having a polycondensation region; an extruder screw extending axially in the barrel through the region and having an outer surface; a guide in the barrel; a plurality of shaft screws extending along and rotatable in the region about respective shaft-screw axes parallel to the barrel axis, partially surrounded by the guide, having axially opposite ends, and having outer surfaces spaced from the guide and from the outer surface of the extruder screw by a distance at least equal to 0; means for rotating the shaft screws about the respective shaft-screw axes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An extruder comprising:
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an elongated barrel centered on a barrel axis and having a polycondensation region; an extruder screw extending axially in the barrel through the region and having in the region a shaft section having an outer surface; a guide in the barrel; a plurality of shaft screws extending along and rotatable about respective shaft-screw axes in the region parallel to the barrel axis, partially surrounded by the guide, having axially opposite ends, and having outer surfaces spaced from the guide and from the outer surface of the extruder screw by a distance at least equal to 0; a respective gear fixed at each end of each of the shaft screws; a pair inner ring gears fixed on the extruder screw and meshing with the gears on the shaft screws; and a pair of outer ring gears fixed in the barrel and also meshing with the gears on the shaft screws. - View Dependent Claims (20)
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Specification