Thermoplastic films with visually-distinct stretched regions and methods for making the same

Patent metadata

Field	Value
Publication number	US-9381697-B2
Application number	US-201213454412-A
Country	US
Kind code	B2
Filing date	Apr 24, 2012
Priority date	Apr 25, 2011
Publication date	Jul 5, 2016
Grant date	Jul 5, 2016

Abstract

Thermoplastic films include intermittent stretched regions that are visually distinct from un-stretched regions. The stretched regions can be white, opaque, and non porous. The thermoplastic films with visually-distinct stretched regions can be formed into bags for use as trash can liners or food storage. Additionally, methods of stretching thermoplastic films to create non-porous, white, and opaque stretched regions include incrementally stretching a film of a thermoplastic material and a voiding agent.

First claim

We claim:

1. A thermoplastic bag, comprising:
first and second sidewalls of a thermoplastic film that comprises linear low-density polyethylene and a voiding agent, the voiding agent being between 5 and 25 percent by weight of the first and second sidewalls, the first and second sidewalls being joined along three edges;
a plurality of un-stretched regions formed in one or more of the first sidewall or the second sidewall, the un-stretched regions having a first average thickness; and
a plurality of cold-stretched regions intermittently dispersed about the un-stretched regions, the cold-stretched regions having a second average thickness that is smaller than the first average thickness;
wherein the cold-stretched regions are non-porous and more opaque than the un-stretched regions.

2. The thermoplastic bag as recited in claim 1 , wherein the thermoplastic film comprises between about 65 and about 99 percent by weight of a thermoplastic material, and between 5 and 20 percent by weight of the voiding agent.

3. The thermoplastic bag as recited in claim 1 , wherein a color of the cold-stretched regions differs from a color of the un-stretched regions.

4. The thermoplastic bag as recited in claim 2 , wherein the voiding agent comprises calcium carbonate.

5. The thermoplastic bag as recited in claim 1 , wherein the un-stretched regions are non-porous.

6. The thermoplastic bag as recited in claim 1 , wherein the cold-stretched regions comprise one or more of:
stripes extending along the thermoplastic film in a direction transverse to a direction in which the thermoplastic film was extruded;
stripes extending along the thermoplastic film in a direction in which the thermoplastic film was extruded; or
discontinuous strainable networks extending in a direction transverse to direction in which the thermoplastic film was extruded.

7. The thermoplastic bag as recited in claim 6 , wherein the cold-stretched regions comprise:
stripes extending along the thermoplastic film in a direction in which the thermoplastic film was extruded; and
stripes extending along the thermoplastic film in a direction transverse to a direction in which the thermoplastic film was extruded.

8. The thermoplastic bag as recited in claim 6 , wherein the cold-stretched regions comprise discontinuous strainable networks arranged in diamond patterns.

9. The thermoplastic bag as recited in claim 1 , further comprising:
a first section, the first plurality of cold-stretched regions being located entirely in the first section; and
a second un-stretched section.

10. A thermoplastic bag, comprising:
first and second sidewalls of a thermoplastic film that comprises a voiding agent, the voiding agent being between 5 and 20 percent by weight of the first and second sidewalls, the first and second sidewalls being joined along three edges;
a plurality of thick regions formed in one or more of the first sidewall or the second sidewall, the thick regions having a first average thickness; and
a plurality of cold-stretched regions alternating with the thick regions, the cold-stretched regions having a second average thickness that is smaller than the first average thickness;
wherein the cold-stretched regions are non-porous and more opaque than the thick regions.

11. The thermoplastic bag as recited in claim 10 , wherein the thermoplastic film comprises between about 65 and about 99 percent by weight of a thermoplastic material, and between about 10 and about 15 percent by weight of the voiding agent.

12. The thermoplastic bag as recited in claim 11 , wherein the thermoplastic material comprises linear low density polyethylene.

13. The thermoplastic bag as recited in claim 11 , wherein the voiding agent comprises calcium carbonate.

14. The thermoplastic bag as recited in claim 11 , wherein the voiding agent comprises between 15 percent by weight of the thermoplastic film.

15. The thermoplastic bag as recited in claim 10 , wherein a color of the cold-stretched regions differs from a color of the thick regions.

16. The thermoplastic bag as recited in claim 10 , wherein an average thickness of the cold-stretched regions is less than an average thickness of the thick regions.

17. The thermoplastic bag as recited in claim 10 , wherein the cold-stretched regions comprise one or more of:
stripes extending along the thermoplastic film in a direction transverse to a direction in which the thermoplastic film was extruded;
stripes extending along the thermoplastic film in a direction in which the thermoplastic film was extruded; or
discontinuous strainable networks extending in a direction transverse to direction in which the thermoplastic film was extruded.

18. The thermoplastic bag as recited in claim 17 , wherein the cold-stretched regions comprise:
stripes extending along the thermoplastic film in a direction in which the thermoplastic film was extruded; and
stripes extending along the thermoplastic film in a direction transverse to a direction in which the thermoplastic film was extruded.

19. The thermoplastic bag as recited in claim 10 , wherein the cold-stretched regions comprise discontinuous strainable networks arranged in diamond patterns.

20. The thermoplastic bag as recited in claim 19 , further comprising:
a first section, the first plurality of stretched regions being located entirely in the first section; and
a second thick section.

Assignees

• Dorsey Robert T
• Borchardt Michael G
• Glad Products Co

Inventors

• Dorsey Robert T
• Borchardt Michael G

Classifications

• B29C55/08

  transverse to the direction of feed · CPC title

• Y02W90/11

  Cross-Sectional Technologies · mapped topic

• B65D33/01

  Ventilation or drainage of bags · CPC title

• B29C55/06

  parallel with the direction of feed · CPC title

• Y10T428/2457

  Parallel ribs and/or grooves · CPC title