Method for producing recycled product, recycled resin pellet, and recycled film

Patent metadata

Field	Value
Publication number	US-11731318-B2
Application number	US-201916566291-A
Country	US
Kind code	B2
Filing date	Sep 10, 2019
Priority date	Mar 31, 2017
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

A method includes producing recycled products from a plurality of used absorbent articles, each including a top sheet, a back sheet and an absorbent body including absorbent body materials, by recovering a plurality of structural members from the plurality of used absorbent articles. At least one of the top sheet and the back sheet includes a film. The method includes: separating the plurality of used absorbent articles into a plurality of the films and the absorbent body materials; sorting the plurality of films into a plurality of types of recyclable films according to the filler contents of the plurality of films; and forming a plurality of types of recycled resin pellets from the plurality of types of recyclable films.

First claim

What is claimed is:

1. A method of producing recycled products from a plurality of used absorbent articles by recovering a plurality of structural members from the plurality of used absorbent articles, wherein each of the plurality of used absorbent articles comprises a top sheet, a back sheet, and an absorbent body comprising absorbent body materials, and wherein at least one of the top sheet and the back sheet comprises a film, the method comprising:
separating the plurality of used absorbent articles into a plurality of the films and the absorbent body materials;
sorting the plurality of films into a plurality of types of recyclable films according to filler contents of the plurality of films; and
forming a plurality of types of recycled resin pellets from the plurality of types of recyclable films.

2. The method according to claim 1 , wherein the plurality of films is sorted into the plurality of types of recyclable films based on a difference in specific gravity between the plurality of films.

3. The method according to claim 2 , wherein the plurality of films is sorted into the plurality of types of recyclable films by a cyclone method.

4. The method according to claim 3 , further comprising:
selecting at least one type of recycled resin pellet from among the plurality of types of recycled resin pellets based on one or more properties of a recycled film that is to be formed, and
forming the recycled film using at least the selected type of recycled resin pellet.

5. The method according to claim 2 , further comprising:
selecting at least one type of recycled resin pellet from among the plurality of types of recycled resin pellets based on one or more properties of a recycled film that is to be formed; and
forming the recycled film using at least the selected type of recycled resin pellet.

6. The method according to claim 2 , wherein the film and the absorbent body materials are connected at joining sections by an adhesive, and
wherein in the separating of the plurality of used absorbent articles, the adhesive at the joining sections is removed by dissolving the adhesive with a solvent.

7. The method according to claim 6 , wherein in the separating of the plurality of used absorbent articles, the plurality of films is heat-dried to remove the solvent.

8. The method according to claim 1 , further comprising:
selecting at least one type of recycled resin pellet from the plurality of types of recycled resin pellets based on one or more properties of a recycled film that is to be formed; and
forming the recycled film using at least the selected type of recycled resin pellet.

9. The method according to claim 1 , wherein the film and the absorbent body materials are connected at joining sections by an adhesive, and
wherein in the separating of the plurality of used absorbent articles, the adhesive at the joining sections is removed by dissolving the adhesive with a solvent.

10. The method according to claim 9 , wherein in the separating of the plurality of used absorbent articles, the plurality of films is heat-dried to remove the solvent.

11. The method according to claim 1 , wherein in the separating of the plurality of used absorbent articles,
the plurality of used absorbent articles is swelled with water,
the plurality of swelled used absorbent articles is disintegrated into the plurality of films and the absorbent body materials by applying a physical shock to the plurality of swelled used absorbent articles, and
the plurality of films and the absorbent body materials are separated.

12. The method according to claim 11 , wherein the absorbent body materials include superabsorbent polymers and pulp fibers, and
wherein in the separating of the plurality of used absorbent articles, the superabsorbent polymers are inactivated in an acidic aqueous solution, and
wherein in the separating of the plurality of used absorbent articles, the plurality of films is separated from a mixture containing the pulp fibers, the inactivated superabsorbent polymers, and any waste water discharged from the inactivation of the superabsorbent polymers.

13. The method according to claim 11 , wherein when the plurality of used absorbent articles is disintegrated,
the plurality of swelled used absorbent articles is loaded into a horizontal-axis rotary drum, and
the physical shock is applied to the plurality of swelled used absorbent articles by rotating the rotary drum, raising the plurality of swelled used absorbent articles from a lower area that is further downward in a vertical direction inside the rotary drum to an upper area that is further upward, and allowing the plurality of swelled used absorbent articles to fall by gravity from the upper area to the lower area and physically impact an inner wall of the rotary drum in the lower area.

14. The method according to claim 11 , wherein in the swelling of the used absorbent article, the water is at a temperature between 70° C. to 98° C., and
wherein each of the plurality of swelled used absorbent articles contains the water in an amount of 90 mass % or greater of a maximum absorption of each of the plurality of used absorbent articles.

15. The method according to claim 1 , wherein the plurality of used absorbent articles are at least one selected from a group consisting of a paper diaper, a urine-absorbing pad, a sanitary napkin, a bed sheet and a pet sheet.

Assignees

• Unicharm Corp

Inventors

• Konishi Takayoshi
• Hiraoka Toshio
• Kameda Noritomo

Classifications

• B09B2101/67

  Diapers or nappies · CPC title

• B09B3/70

  Chemical treatment, e.g. pH adjustment or oxidation (involving an extraction step B09B3/80) · CPC title

• B09B3/35

  Shredding, crushing or cutting · CPC title

• B29B17/02 Primary

  Separating plastics from other materials · CPC title

• A61F13/539

  characterised by the connection of the absorbent layers with each other or with the outer layers · CPC title