Method for manufacturing recycled pulp from used sanitary products

Patent metadata

Field	Value
Publication number	US-11319670-B2
Application number	US-202016785922-A
Country	US
Kind code	B2
Filing date	Feb 10, 2020
Priority date	Jun 12, 2014
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A recycled pulp that is reusable sanitary products is efficiently manufactured by recovering pulp fiber from used sanitary products containing the pulp fiber and a polymer absorbent. The method of the present invention comprises: a step applying a mechanical force to the used sanitary products in an aqueous solution containing a polyvalent metal ion or an acidic aqueous solution with a pH of 2.5 or lower and thus degrading the used sanitary products into the pulp fiber and other materials; a step separating the pulp fiber from the mixture of the pulp fiber and other materials that has been formed in the degradation step; and a step treating the pulp fiber thus separated with an ozone-containing aqueous solution with a pH of 2.5 or lower.

First claim

The invention claimed is:

1. A recycled pulp having an ash content of 0.11% by weight or less, wherein the recycled pulp is recovered from a used sanitary product comprising pulp fibers containing organic waste and superabsorbent polymer, wherein the recycled pulp has a water absorption performance ranging from 17.2 g/g to 18.1 g/g.

2. The recycled pulp of claim 1 , wherein the ash content ranges from 0.05% by weight to 0.11% by weight.

3. The recycled pulp of claim 1 , wherein the recycled pulp includes fluff pulp fibers.

4. The recycled pulp of claim 1 , wherein the recycled pulp includes chemical pulp fibers.

5. The recycled pulp of claim 1 , wherein the recycled pulp has a water retention performance of 7.92 g/g to 8.3 g/g.

6. The recycled pulp of claim 1 , wherein the ash content is 0.06% by weight or less.

7. A sanitary product comprising:
recycled pulp fibers having an ash content of about 0.11% by weight or less, wherein the recycled pulp is recovered from a used sanitary product comprising pulp fibers containing organic waste and superabsorbent polymer, wherein the recycled pulp has a water absorption performance ranging from 17.2 g/g to 18.1 g/g; and
a superabsorbent polymer (SAP).

8. The sanitary product of claim 7 , wherein the ash content ranges from about 0.05% by weight to about 0.11% by weight.

9. The sanitary product of claim 7 , wherein the sanitary product is selected from the group consisting of a disposable diaper, an incontinence pad, a urine collection pad, a sanitary napkin and a panty liner.

10. The sanitary product of claim 7 , wherein the recycled pulp fibers include fluff pulp fibers.

11. The sanitary product of claim 7 , wherein the recycled pulp fibers include chemical pulp fibers.

12. The sanitary product of claim 7 , wherein the SAP comprises a starch-based particulate, an acrylic acid-based particulate or an amino acid-based particulate.

13. The sanitary product of claim 7 , wherein the SAP comprises a starch-based fibrous polymer, an acrylic acid-based fibrous polymer or an amino acid-based fibrous polymer.

14. A disposable diaper comprising:
recycled pulp fibers having an ash content of about 0.11% by weight or less, wherein the recycled pulp is recovered from a used sanitary product comprising pulp fibers containing organic waste and superabsorbent polymer, wherein the recycled pulp has a water absorption performance ranging from 17.2 g/g to 18.1 g/g; and
a superabsorbent polymer (SAP).

15. The disposable diaper of claim 14 , wherein the ash content ranges from about 0.05% by weight to about 0.11% by weight.

16. The disposable diaper of claim 14 , wherein the recycled pulp fibers include fluff pulp fibers.

17. The disposable diaper of claim 14 , wherein the recycled pulp fibers include chemical pulp fibers.

18. The disposable diaper of claim 14 , wherein the SAP comprises a starch-based particulate, an acrylic acid-based particulate or an amino acid-based particulate.

19. The disposable diaper of claim 14 , wherein the SAP comprises a starch-based fibrous polymer, an acrylic acid-based fibrous polymer or an amino acid-based fibrous polymer.

Assignees

• Unicharm Corp

Inventors

• Konishi Takayoshi
• Hiraoka Toshio

Classifications

• B09B3/38

  Stirring or kneading · CPC title

• 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

• D21H11/14 Primary

  Secondary fibres (working-up waste paper D21C5/02) · CPC title

• D21C9/153

  with ozone · CPC title