Incrementally-stretched thermoplastic films with enhanced look and feel and methods for making the same

Patent metadata

Field	Value
Publication number	US-9260224-B2
Application number	US-201414195582-A
Country	US
Kind code	B2
Filing date	Mar 3, 2014
Priority date	Mar 28, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

Methods of increasing the perceived thickness and strength of a thermoplastic film include incrementally stretching thermoplastic films in the machine direction. In one or more implementations, methods of incrementally stretching thermoplastic films include reducing the gauge of the films while increasing a loft of at least a portion of the film. The methods can involve cold stretching the films and imparting rib patterns and alternating peaks and valleys into the film. The linear ribs can have alternating thick and thin gauges.

First claim

We claim:

1. A method of creating a machine-direction incrementally-stretched film with one or more of increased loft, perceived strength, and an improved tactile fee, the method comprising:
providing a film of a thermoplastic material; and
passing the film through a pair of cold machine direction ring rollers in a manner that causes the pair of cold machine direction ring rollers to:
intermittingly stretch the film and thereby create a ribbed pattern including thick linear ribs and thinner stretched linear ribs, the thick linear ribs and the thinner stretched linear ribs both extending in the transverse direction across the film, the thinner stretched linear ribs being of substantially uniform thickness, and
create a plurality of peaks and valleys only in the thinner stretched linear ribs, the plurality of peaks and valleys extending generally in the machine direction.

2. The method as recited in claim 1 , further comprising cold transverse-direction ring rolling the film.

3. The method as recited in claim 1 , wherein a machine direction depth-of-engagement to pitch ratio used to machine-direction ring roll the film is between 0.5 and 1.0.

4. The method as recited in claim 1 , further comprising forming the machine-direction incrementally-stretched film into a bag.

5. The method as recited in claim 4 , wherein the film only passes through one pair of intermeshing rollers prior to forming the machine-direction incrementally-stretched film into the bag.

6. The method as recited in claim 1 , further comprising non-continuously laminating at least a portion of the film to a second thermoplastic film by a process selected from the group consisting of adhesive bonding, ultrasonic bonding, thermal bonding, embossing, ring rolling, SELFing, and combinations thereof.

7. The method as recited in claim 1 , further comprising passing the film through a second pair of ring rollers in a manner that causes the second pair of ring rollers to provide the plurality of peaks and valleys with a loft that is greater than a gauge of the thick linear ribs.

8. The method as recited in claim 1 , further comprising folding the film in half after passing the film through the cold machine direction ring rollers.

9. The method as recited in claim 1 , further comprising folding the film in half before passing the film through the cold machine direction ring rollers.

10. The method as recited in claim 1 , wherein the film of a thermoplastic material comprises a uniform gauge prior to passing through the cold machine direction ring rollers.

11. The method as recited in claim 1 , wherein providing the film of the thermoplastic material comprises unrolling the film from a roll and advancing the film in the machine direction.

12. The method as recited in claim 1 , further comprising incrementally stretching only a portion of the film in the transverse direction by passing only the portion of the film through a pair of transverse direction ring rollers.

13. The method as recited in claim 1 , wherein the plurality of peaks and valleys do not follow a tooth pattern of the cold machine direction ring rollers.

14. The method as recited in claim 1 , further comprising passing the film through the pair of cold machine direction ring rollers in a manner that causes the pair of cold machine direction ring rollers to decrease the gauge by weight of the film.

15. The method as recited in claim 14 , wherein the decrease in the gauge by weight of the film is between 25% and 15%.

16. A method of creating a machine-direction incrementally-stretched film with one or more of increased loft, perceived strength, and an improved tactile fee, the method comprising:
providing a film of a thermoplastic material; and
passing the film through a pair of ring rollers in a manner that causes the pair of ring rollers to:
intermittingly stretch the film in a first direction and thereby create a ribbed pattern including thick linear ribs and thinner stretched linear ribs, the thick linear ribs and the thinner stretched linear ribs both extending in a second direction that is transverse to the first direction, the thinner stretched linear ribs being of substantially uniform thickness, and
create a plurality of undulations only in the thinner stretched linear ribs, the plurality of undulations extending generally in the first direction.

17. The method as recited in claim 16 , wherein the ring rollers are machine direction ring rollers and the first direction is the machine direction.

18. The method as recited in claim 17 , further comprising incrementally stretching only a portion of the film in the transverse direction by passing only the portion of the film through a pair of transverse direction ring rollers.

19. The method as recited in claim 16 , further comprising passing the film through the pair of ring rollers in a manner that causes the pair of ring rollers to provide the plurality of undulations with a loft that is greater than a gauge of the thick linear ribs.

20. The method as recited in claim 16 , wherein the plurality of undulations do not follow a tooth pattern of the ring rollers.

Assignees

• Glad Products Co

Inventors

• Borchardt Michael G
• Dorsey Robert T

Classifications

• B31B2155/0014

  having their openings facing transversally to the direction of movement · CPC title

• B31B70/88

  Printing; Embossing · CPC title

• B31B70/008

  Stiffening or reinforcing (B31B70/876 takes precedence) · CPC title

• B65D33/007

  for facilitating the separation of the two walls, e.g. walls of inequal height, tabs; for maintaining the mouth of the sack or bag open · CPC title

• B65D33/00 Primary

  Details of, or accessories for, sacks or bags · CPC title