Incrementally stretched films with increased tear resistance and methods for making the same

摘要

Methods of incrementally stretching thermoplastic films in the machine direction include elongating the films in the machine direction without reducing the films' machine-direction tear resistance. In one or more implementations, methods of incrementally stretching thermoplastic films include reducing the gauge of the films without reducing the films' machine-direction tear resistance. The methods can involve cold stretching the films and imparting transverse-direction extending linear rib pattern into the film. The linear ribs can have alternating thick and thin gauges. Incrementally stretched thermoplastic films can have a machine-direction tear resistance that is equal to or greater than the machine-direction tear resistance of the film prior to stretching.

主权项

1. A machine-direction incrementally-stretched film of thermoplastic material comprising:
a set of linear ribs extending across the film in a direction transverse to a direction in which the film was extruded, the linear ribs each having a first average thickness; and a set of stretched linear sections extending across the film in the transverse direction, the stretched linear sections each being positioned between adjacent linear ribs, the stretched linear sections each having a second average thickness that is smaller than the first average thickness; wherein the film has:
a gauge-by-weight that is from 10.0% smaller than to 5.9% larger than a gauge-by-weight of a film of the thermoplastic material having a substantially uniform thickness equal to the first average thickness; anda machine direction tear resistance that is equal to or greater than a machine direction tear resistance of the film of the thermoplastic material having the substantially uniform thickness equal to the first average thickness.