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US 4,465,649 AGranted
Method and system for extruding tubular foamed polymer sheet
AssigneeMobil Oil Corporation
InventorDavid E. Johnson
Life of this patent
Estimating the term…
Abstract
A process and system for the formation of a polymer foam sheet of comparatively uniform biaxially orientation and comparatively uniform dimensions prepared by extruding polymer foam so that it rides on a fluid bearing film between the point of extrusion and a point of diameter expansion of the extruding tube.
Claims21
A method for the production of polymeric foam sheet of uniform dimensions and orientation comprising:
- (a) extruding a composition comprising a molten polymer containing a foaming agent therein through an annular die;
- (b) passing the extruding tube over a diameter-increasing sizing member spaced from said die;
- (c) positioning an envelope within said tube between said die and said sizing drum, said envelope having a perforated conical shaped wall conforming to the slope of the extruding tube and spaced closely adjacent thereto, the remainder of said envelope being imperforate, said perforated conical shaped wall extending from adjacent said annular die to adjacent said sizing member;
- and
- (d) maintaining a positive fluid pressure within said envelope so as to cause said tube to ride from said die to over said sizing drum on a uniformly thin layer of fluid maintained by a uniform pressure drop through said perforated wall.
2 more elements
A system for extruding polymeric foam sheet of at least substantially uniform dimensions and orientation comprising in combination:
- (a) means for extruding a composition comprising a molten polymer containing a foaming agent therein through an annular die;
- (b) means for drawing the extruding polymer foam in tube form over a diameter-increasing sizing member spaced from said die;
- (c) envelope means positioned within said tube between said die and said sizing member, said envelope means having a perforated conical shaped wall conforming to the slope of the extruding tube and spaced closely adjacent thereto, the remainder of said envelope being imperforate, said perforated conical shaped wall extending from adjacent said annular die to adjacent said sizing member;
- (d) means for maintaining a positive fluid pressure within said envelope so as to cause said extruding tube to ride from said die to over said sizing drum on a uniformly thin layer of fluid maintained on said perforated wall by a uniform pressure drop through said perforated wall.
1 more element
Dependencies are inferred from the claim text.