Bag

Patent metadata

Field	Value
Publication number	US-10245778-B2
Application number	US-201614997030-A
Country	US
Kind code	B2
Filing date	Jan 15, 2016
Priority date	Mar 10, 2010
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

A thermoplastic bag may include a sidewall that may have a plurality of first and second ribs formed therein. The first ribs may be longer in length but shorter in height than the second ribs. The second ribs may be arranged in discrete networks that appear superimposed over the first ribs. The second ribs may normally remain in a bent-over configuration. When a force is applied, the second ribs may expand the area of the sidewall so that the bag may easily accommodate large objects. To produce the bag, a thermoplastic web may be directed between opposing first and second rollers. One of the rollers may include ridges that may have first and second segments of differing heights that correspond to the differing heights of the first and second ribs. The formation of the first ribs may increase the width of the web.

First claim

The invention claimed is:

1. A method of forming a thermoplastic web comprising:
providing first and second rollers, the rollers arranged adjacent to each other, a surface of the first roller including a plurality of ridges protruding radially outward, the ridges of the first roller arranged parallel to and axially spaced from one another, the ridges of the first roller having first segments of a first height and a first shape and second segments of a second height and a second shape, the second height being greater than the first height and the second shape being different than the first shape;
providing a web of pliable thermoplastic material, the web having an initial width between a first edge and a second edge;
rotating the first and second rollers in opposite rotational directions;
advancing the web along a machine direction between the first and second rollers;
plastically stretching first portions of the web with the first segments to form a first plurality of ribs and to increase the initial width of the web; and
stretching second portions of the web with the second segments to form a second plurality of ribs that are displaced with respect to an initial plane of the web and retain the second shape of the second segments such that the second plurality of ribs can unbend or flatten to provide the web with elasticity.

2. The method of claim 1 , wherein plastically stretching the web molecularly re-orients the thermoplastic material of the plastically stretched first portions of the web.

3. The method of claim 2 , wherein the ribs of the first plurality of ribs extend in a direction parallel to the machine direction.

4. The method of claim 3 , wherein the first plurality of ribs have a third height and the second plurality of ribs have a fourth height, wherein the fourth height is greater than the third height.

5. The method of claim 4 , wherein the second plurality of ribs have structural elastic like film properties, and wherein the first plurality of ribs are devoid of structural elastic like film properties.

6. The method of claim 5 , wherein the first plurality of ribs stretch under tension and the second plurality of ribs unbend under tension.

7. The method of claim 5 , wherein stretching the second portions of the web with the second segments to form the second plurality of ribs comprises forming differentiated networks of ribs that expand under tension.

8. The method of claim 5 , wherein:
the first plurality of ribs are defined by areas of the thermoplastic web stretched in a longitudinal direction, the longitudinal direction being in-plane with both the machine direction and a transverse direction of the thermoplastic web; and
the second plurality of ribs are defined by areas of thermoplastic web stretched in an outward direction relative to a plane including both the machine direction and the transverse direction such that the second plurality of ribs are vertically displaced relative to the first plurality of ribs.

9. The method of claim 1 , further comprising forming the thermoplastic web into a bag.

10. The method of claim 9 , wherein forming the thermoplastic web into the bag comprises forming the thermoplastic web into a trash bag.

11. The method of claim 1 , wherein plastically stretching the first portions of the web with the first segments to form the first plurality of ribs and stretching the second portions of the web with the second segments to form the second plurality of ribs comprises forming a continuous ribbed structure across the web that alternates repeatedly between ribs of the first plurality of ribs and ribs of the second plurality of ribs.

12. The method of claim 11 , wherein plastically stretching the first portions of the web with the first segments to form the first plurality of ribs and stretching the second portions of the web with the second segments to form the second plurality of ribs comprises forming the first plurality of ribs and the second plurality of ribs such that the first and second plurality of ribs are aligned in the machine direction and a direction transverse to the machine direction.

13. The method of claim 1 , wherein stretching the second portions of the web with the second segments to form the second plurality of ribs comprises forming ribs having lengths that vary with respect to each other.

14. The method of claim 7 , wherein forming the differentiated networks of ribs comprises forming diamond-shaped differentiated networks.

15. The method of claim 1 , wherein plastically stretching the first portions of the web with the first segments to form the first plurality of ribs comprises engaging the web against flat surfaces of the first segments.

16. The method of claim 15 , wherein stretching the second portions of the web with the second segments to form the second plurality of ribs comprises engaging the web against rounded surfaces of the second segments.

17. A method of forming a thermoplastic bag comprising:
providing first and second rollers, the rollers arranged adjacent to each other, a surface of the first roller including a plurality of ridges protruding radially outward, the ridges of the first roller arranged parallel to and axially spaced from one another, the ridges of the first roller having first segments of a first height and a first shape and second segments of a second height and a second shape, the second height being greater than the first height and the second shape being different than the first shape;
providing a web of pliable thermoplastic material, the web having an initial width between a first edge and a second edge;
rotating the first and second rollers in opposite rotational directions;
advancing the web along a machine direction between the first and second rollers;
plastically stretching first portions of the web with the first segments to form a first plurality of ribs and to increase the initial width of the web;
stretching second portions of the web with the second segments to form a second plurality of ribs that are displaced with respect to an initial plane of the web and retain the second shape of the second segments such that the second plurality of ribs can unbend or flatten to provide the web with elasticity;
heat sealing folded portions of the web together to form side edges; and
perforating heat-sealed portions of the web to separate the thermoplastic bag from the web.

18. The method of claim 17 , wherein the second plurality of ribs have structural elastic like film properties, and wherein the first plurality of ribs are devoid of structural elastic like film properties.

19. The method of claim 18 , wherein the first plurality of ribs stretch under tension and the second plurality of ribs unbend under tension.

20. The method of claim 17 , wherein plastically stretching the first portions of the web with the first segments to form the first plurality of ribs and stretching the second portions of the web with the second segments to form the second plurality of ribs comprises forming a continuous ribbed structure across the web that alternates repeatedly between ribs of the first plurality of ribs and ribs of the second plurality of ribs.

Assignees

• Glad Products Co

Inventors

• Maxwell Jason R
• Melvan Jack F

Classifications

• B29K2105/256

  Sheets, plates, blanks or films · CPC title

• B29L2031/7128

  Bags, sacks, sachets (tea bags B29L2031/7122; medical bags B29L2031/7148) · CPC title

• B29K2101/12

  Thermoplastic materials · CPC title

• B29C55/18

  by squeezing between surfaces, e.g. rollers · CPC title

• B65D33/02

  Local reinforcements or stiffening inserts, e.g. wires, strings, strips or frames {(B65D33/007 takes precedence)} · CPC title