Incrementally stretched films with enhanced properties and methods for making the same

摘要

Methods of enhancing one or more physical properties of a thermoplastic film include incrementally stretching thermoplastic films in the machine direction and/or transverse direction. 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 rib patterns 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 approximately equal to or greater than the machine-direction tear resistance of the film prior to stretching.

主权项

1. A thermoplastic bag, comprising:
first and second sidewalls comprising a blown incrementally-stretched thermoplastic film formed by stretching an un-incrementally-stretched thermoplastic film; and a first set of alternating thicker and thinner linear ribs extending across the first sidewall in a direction in which the incrementally-stretched thermoplastic film was extruded; wherein the blown incrementally-stretched thermoplastic film has a machine direction tear resistance that is approximately equal to or greater than a first machine direction tear resistance of the un-incrementally-stretched thermoplastic film; wherein the blown incrementally-stretched thermoplastic film comprises a transverse direction tear resistance that is reduced by a first percent reduction compared to a first transverse direction tear resistance of the un-incrementally-stretched thermoplastic film; wherein the blown incrementally-stretched thermoplastic film comprises a gauge by weight reduced by a second percent reduction compared to a first gauge by weight of the un-incrementally-stretched thermoplastic film; wherein the first percent reduction of the transverse direction tear resistance is less than the second percent reduction of the gauge by weight.