Methods of making multi-layered bags with enhanced properties

Patent metadata

Field	Value
Publication number	US-9669595-B2
Application number	US-201414481623-A
Country	US
Kind code	B2
Filing date	Sep 9, 2014
Priority date	Nov 16, 2009
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

Methods for creating multi-layered incrementally-stretched and incrementally-laminated bags with increased or maintained strength are described herein. An increased level of strength is achieved by bonding adjacent layers of a multi-layer film together in a manner that the bond strength of the laminated layers is less than a strength of a weakest tear resistance of the individual first and second film layers. The inventors have surprisingly found that such a configuration of light bonding provides increased and unexpected strength properties to the multi-layer film as compared to a monolayer film of equal thickness or a multi-layer film in which the plurality of layers are tightly bonded together.

First claim

We claim:

1. A method for forming a multi-layered incrementally-stretched and incrementally-laminated bag, the method comprising:
creating a film assembly of a folded inner film-layer within a folded outer film-layer;
incrementally stretching and incrementally bonding adjacent layers of the film assembly together by passing the film assembly through a pair of intermeshing rollers;
incrementally heat sealing the incrementally stretched and incrementally bonded film assembly; and
perforating the incremental heat seals of the incrementally stretched and incrementally bonded film assembly to define bags.

2. The method as recited in claim 1 , wherein passing the film assembly through a pair of intermeshing rollers comprises passing the film assembly through a pair of machine-direction ring rollers.

3. The method as recited in claim 2 , wherein incrementally stretching and incrementally bonding adjacent layers of the film assembly together comprises incrementally stretching the film assembly in the machine direction to form transverse-direction extending stretched regions and transverse-direction extending thicker ribs.

4. The method as recited in claim 3 , wherein incrementally stretching and incrementally bonding adjacent layers of the film assembly together further comprises forming transverse-direction extending bonds securing transverse-direction thicker ribs in the outer film-layer to transverse-direction thicker ribs in the inner film-layer.

5. The method as recited in claim 4 , wherein the inner film-layer and the outer film-layer are both predominately oriented in the machine direction.

6. The method as recited in claim 5 , further comprising orienting the transverse-direction extending stretched regions further in the machine direction such that the transverse-direction extending stretched regions are more oriented in the machine direction than the transverse-direction thicker ribs.

7. The method as recited in claim 4 , further comprising breaking bonds between folded halves of the inner film-layer of the film assembly by passing a spreader bar between the folded halves of the inner film-layer of the film assembly.

8. The method as recited in claim 4 , further comprising forming a strainable network in at least a portion of the film assembly by passing the film assembly through a second pair of intermeshing rollers.

9. The method as recited in claim 8 , wherein forming a strainable network in at least a portion of the film assembly forming a strainable network only in a middle portion of the film assembly.

10. The method as recited in claim 9 , further comprising:
inserting a draw-tape between the inner film-layer and the outer film-layer; and
forming a hem seal between the draw tape and the middle portion of the film including the strainable network.

11. A method for forming a multi-layered incrementally-stretched and incrementally-laminated bag, the method comprising:
placing a folded inner film-layer within a folded outer film-layer to create a film assembly having four layers;
passing the four layers of the film assembly simultaneously together through a pair of machine-direction intermeshing rollers to form transverse-direction extending stretched regions, transverse-direction extending thicker ribs, and transverse-direction extending bonds that secure transverse-direction thicker ribs in outer film-layer to transverse-direction thicker ribs in the inner film-layer; and
forming the film assembly into one or more bags.

12. The method as recited in claim 11 , further comprising passing the four layers of the film assembly simultaneously together through a pair of SELFing rollers to further stretch the film assembly and form a strainable network in the film assembly.

13. The method as recited in claim 12 , wherein passing the four layers of the film assembly simultaneously together through the pair of SELFing rollers comprises passing the four layers of the film assembly simultaneously together through a pair of SELFing rollers having intermeshing teeth extending along only a portion of a length of each roller.

14. The method as recited in claim 13 , further comprising passing the four layers of the film assembly simultaneously together through a pair of transverse-direction ring rollers to form machine-direction extending stretched regions, machine-direction extending thicker ribs, and machine-direction extending bonds that secure machine-direction thicker ribs in the outer film-layer to machine-direction thicker ribs in the inner film-layer.

15. The method as recited in claim 12 , wherein the four layers of the film assembly consist of a first portion of the outer film-layer, a first portion of the inner film-layer, a second portion of the inner film-layer, and a second portion of the outer film-layer.

16. The method as recited in claim 15 , wherein passing the four layers of the film assembly simultaneously together through the pair of machine-direction intermeshing rollers further form transverse-direction extending bonds that secure transverse-direction thicker ribs in the first portion of the inner film-layer to transverse-direction thicker ribs in the second portion of the inner film-layer.

17. The method as recited in claim 16 , further comprising breaking the transverse-direction extending bonds that secure transverse-direction thicker ribs in the first portion of the inner film-layer to transverse-direction thicker ribs in the second portion of the inner film-layer without breaking the transverse-direction extending bonds that secure transverse-direction thicker ribs in outer film-layer to transverse-direction thicker ribs in the inner film-layer by passing a spreader bar between the first portion of the inner film-layer and the second portion of the inner film-layer.

18. The method as recited in claim 13 , wherein the inner film-layer and the outer film-layer are both predominately oriented in the machine direction.

19. The method as recited in claim 18 , further comprising orienting the transverse-direction extending stretched regions further in the machine direction such that the transverse-direction extending stretched regions are more oriented in the machine direction than the transverse-direction thicker ribs.

20. A method for forming a multi-layered incrementally-stretched and incrementally-laminated bag, the method comprising:
placing a folded inner film-layer within a folded outer film-layer to create a film assembly having four layers;
passing the four layers of the film assembly simultaneously together through a pair of machine-direction intermeshing rollers to form transverse-direction extending stretched regions, transverse-direction extending thicker ribs, and transverse-direction extending bonds that secure transverse-direction thicker ribs in the outer film-layer to transverse-direction thicker ribs in the inner film-layer;
passing the four layers of the film assembly simultaneously together through a pair of SELFing rollers to further stretch only a portion of the film assembly and form a strainable network in only the further stretched portion of the film assembly; and
forming the film assembly into one or more bags.

Assignees

• Glad Products Co

Inventors

• Borchardt Michael G
• Broering Shaun T
• Dorsey Robert T
• Wogelius Donald E
• Maxwell Jason R
• Binger Scott W

Classifications

• B32B2307/558

  Impact strength, toughness · CPC title

• B32B7/12

  using interposed adhesives or interposed materials with bonding properties · CPC title

• B32B2307/746

  Slipping, anti-blocking, low friction · CPC title

• B32B2555/02

  Diapers or napkins · CPC title

• B32B27/16

  specially treated, e.g. irradiated · CPC title