The Dow Chemical Company

Gordon E Gould

Robert A Luecke

William R Park

Paul M Curtin

William D Carmody

A process and apparatus are disclosed for reducing the carbonization of a thermally degradable barrier material during the extrusion of a multilayer laminate. A core extrudate of barrier material is extruded with a core extruder. A preencapsulation means is provided adjacent the downstream end of the core extruder. The core extrudate is joined with a preencapsular extrudate in the preencapsulation means in a coaxial relation wherein the preencapsular extrudate is disposed radially outwardly of the core extrudate. The preencapsulated core extrudate is then directed to a feed block and coextrusion die for incorporation in the coextruded multilayer film.

Extrusion apparatus and process for production of multilayer film

A filtering system for use in coextrusion apparatus, and particularly for removing carbon particles from a core extrudate of thermally degradable barrier material which has been preencapsulated with a preencapsular material. The filter includes a casing and a frame mounted to the casing. A coarse filter screen through which the component streams can flow is also provided. The coarse filter screen is mounted to the frame and is composed of a web of woven strands having a sufficiently small diameter so as to permit the preencapsulated core extrudate to pass through and emerge from the coarse filter screen without substantial mixing of the barrier material and the preencapsular material. The fine filter screen is supported by the coarse filter screen upstream of the coarse filter screen.

Filtering system for use in coextrusion apparatus and method of use

A tubular film and method for making the film by extrusion provide a multi-layer film having a central layer of barrier material which overlaps itself by a substantial distance along a weld line. The film includes inner and outer adhesive layers positioned on opposite sides of the central barrier layer, which adhesive layers completely encapsulated the central barrier layer. Finally, the film includes inner and outer surface layers. The inner surface layer is positioned within the inner adhesive layer, and the outer surface layer is positioned outside the outer adhesive layer.

Tubular, multi-layer film and method of making

Rolls of household or consumer type films or wrapping materials are provided with a curled leading edge that is ideally suited as a grasping tab for starting initial withdrawal of the film such as from a standard consumer type dispensing carton. The invention is applied to films exhibiting relatively high residual shrinkage or stress relaxation and is practiced by applying a coating to, or alternately solvent treating, the leading edge, in a manner that unbalances the rate of shrinkage at the opposite surfaces of the edge, thereby inducing a curling effect. Further attributes of such a starting feature would include easy identification of the leading edge, and the lessening of sensitivity to tear propagation such as from a notch or a like tear propagating flaw as may be left in the leading edge by the film cutter bar.

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Newark, OH, United States of America

Gordon E Gould