Coextruded profiled webs
Assignee3M Innovative Properties Company
InventorsRonald W. Ausen, Janet A. Venne, Jayshree Seth
Life of this patent
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Abstract
A method that includes coextruding two or more thermoplastic resin streams through a profiled die plate, which die plate is shaped to form a nonplanar film (three dimensional) preferably with a regularly oscillating peak and valley structure that oscillates from a top surface to a bottom surface forming longitudinally extending ridges on both faces of the film. The film is formed by coextruding the film through the oscillating die plate opening causing partitioning of the resins in different zones in the width direction of the film. Flattening of the film results in a film with side-by-side zones formed of different polymers or relative proportions of polymers.
Claims25
A method for forming a thermoplastic polymeric film comprising:
- (a) combining two or more polymer melt streams forming a combined multilayer melt stream;
- (b) extruding the combined multilayer melt stream in a die forming a substantially planar combined flowstream in the die having an upper zone and a lower zone;
- (c) extruding the substantially planar combined flowstream through a die plate placed in a die outlet, the die plate having a profiled film cut opening in a front face and adjacent wall portions, the profiled film cut opening having a plurality of peaks and valleys oscillating from an upper region to a lower region, where the substantially planar combined planar flowstream intersects the die plate front face profiled film cut opening and adjacent wall portions, where the profiled film cut opening plurality of peaks and valleys disproportionably partitions at least a portion of the polymer of the substantially planar combined flowstream in the upper zone to the upper region and disproportionably partitions at least a portion of the polymer of the substantially planar combined flowstream in the lower zone to the lower region to form at least upper and lower polymer layers in a formed thermoplastic polymeric film;
- wherein at least one of the polymer layers in the formed thermoplastic polymeric film varies in thickness across the formed film width due to the partitioning of the polymer flow by the plurality of peaks and valleys of the opening, and
- (d) collecting the formed thermoplastic polymeric film, said formed thermoplastic polymeric film having a series of ridges extending as peaks and valleys oscillating from a top surface to a bottom surface, which peaks and valleys extend in a first direction forming continuous ridges, wherein the profiled cut opening is uniform in thickness across the die plate.
Dependencies are inferred from the claim text.