Prestretched elastic film in personal hygiene products

Patent metadata

Field	Value
Publication number	US-11034072-B2
Application number	US-201715806403-A
Country	US
Kind code	B2
Filing date	Nov 8, 2017
Priority date	Nov 9, 2016
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

Stretched elastic films include a polyolefin, a styrene block copolymer, a non-styrene block copolymer, or a combination thereof. Methods for forming polymeric films and articles of manufacture prepared therefrom are described.

First claim

The invention claimed is:

1. A process for making a stretched elastic film comprising the steps of
co-extruding at least a first composition, a second composition, and a third composition to form a molten web, the first composition forming at least one first film layer, the second composition forming at least one second film layer, and the third composition forming at least one third film layer, wherein the at least one first film layer is disposed between the at least one second film layer and the at least one third film layer, wherein the first composition comprises a polyolefin, a styrene block copolymer, a non-styrene block copolymer, or a combination thereof, and wherein the second composition and the third composition are identical or different,
casting the molten web against a surface of a chill roll using an air knife, an air blanket, a vacuum box, or a combination thereof to form a quenched film,
stretching the quenched film in a machine direction in at least a 2:1 draw to form a stretched film, and
relaxing the stretched film to form the stretched elastic film,
wherein the stretched film is not bonded to a non-woven material; and
wherein the stretched elastic film has a load at 100% of less than about 300 grams per inch.

2. The process of claim 1 , wherein the polyolefin comprises low density polyethylene, high density polyethylene, linear low density polyethylene, ultra-low density polyethylene, or a combination thereof.

3. The process of claim 1 , wherein the polyolefin comprises linear low density polyethylene.

4. The process of claim 1 , wherein the polyolefin comprises linear low density polyethylene and the linear low density polyethylene comprises a metallocene polyethylene.

5. The process of claim 1 , wherein the polyolefin comprises polypropylene.

6. The process of claim 1 , wherein the polyolefin comprises polypropylene impact copolymer.

7. The process of claim 1 , wherein the styrene block copolymer comprises styrene-isoprene block copolymer, styrene-(ethylene-butylene) block copolymer, styrene-(ethylene-propylene) block copolymer, styrene-butadiene block copolymer, or a combination thereof.

8. The process of claim 1 , wherein the molten web is cast against the surface of the chill roll under negative pressure by the vacuum box.

9. The process of claim 1 , wherein the molten web is cast against the surface of the chill roll under positive pressure by the air knife.

10. The process of claim 1 , wherein the extruding and the casting are achieved via in-line processing, and wherein the stretching is achieved via post-processing of the quenched film.

11. The process of claim 1 , wherein the stretching in the machine direction is in at least a 3:1 draw.

12. The process of claim 1 , wherein the stretching in the machine direction is in at least a 4:1 draw.

13. The process of claim 1 , wherein at least a portion of the stretching is performed at room temperature.

14. The process of claim 1 , wherein the first film layer is a core layer, and wherein each of the at least one second film layer and the at least one third film layer is an outer skin layer.

15. The process of claim 1 , wherein each of the second composition and the third composition comprises a polyolefin.

16. The process of claim 1 , wherein each of the second composition and the third composition comprises polyethylene, polypropylene, or a combination thereof.

17. The process of claim 1 wherein the second composition and the third composition are identical.

18. The process of claim 1 , wherein the stretched elastic film, after relaxation, has a basis weight of less than or equal to about 50 gsm.

19. The process of claim 1 , wherein the stretched elastic film, after relaxation, has a basis weight of less than or equal to about 30 gsm.

20. The process of claim 1 , wherein the stretched elastic film, after relaxation, has a basis weight of less than or equal to about 20 gsm.

21. The process of claim 1 further comprising ageing the quenched film before the stretching to form an aged film, the aged film having an increased elasticity relative to the quenched film.

22. The process of claim 1 further comprising the step of bonding the stretched elastic film to a non-woven material, wherein the bonding step occurs after the relaxing step.

Assignees

• Berry Global Inc

Inventors

• Middlesworth Jeffrey A

Classifications

• B29C41/42

  Removing articles from moulds, cores or other substrates {(B29C33/444 and B29C37/0017 take precedence)} · CPC title

• B29C55/065

  in several stretching steps · CPC title

• B29C55/06

  parallel with the direction of feed · CPC title

• B29C41/26

  by depositing flowable material on a rotating drum · CPC title

• B29K2023/12

  PP, i.e. polypropylene · CPC title