Method for manufacturing recycled pulp from used sanitary products

Patent metadata

Field	Value
Publication number	US-2020217013-A1
Application number	US-202016818166-A
Country	US
Kind code	A1
Filing date	Mar 13, 2020
Priority date	Jun 12, 2014
Publication date	Jul 9, 2020
Grant date	—

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

1 . A method of processing a used sanitary product, the method comprising:
degrading the used sanitary product in an acid solution having a pH of 2.5 or lower, wherein the used sanitary product includes pulp fibers and a superabsorbent polymer; and applying a mechanical force to the used sanitary product during the degrading.

2 . The method of claim 1 , wherein the acid solution comprises an organic acid.

3 . The method of claim 2 , wherein the organic acid is selected from the group consisting of tartaric acid, glycolic acid, malic acid, citric acid, succinic acid and acetic acid.

4 . The method of claim 2 , wherein the organic acid is citric acid.

5 . The method of claim 1 , further comprising separating pulp fibers and pulp fibers in which superabsorbent polymers remain from the mixture formed in the degrading step to obtain separated pulp fibers.

6 . The method of claim 5 , further comprising treating the separated pulp fibers in an ozone-containing solution.

7 . The method of claim 6 , wherein the ozone-containing solution comprises an acid.

8 . The method of claim 1 , wherein the used sanitary product includes organic waste.

9 . A method of making a sanitary product, the method comprising:
degrading a used sanitary product in an acid solution having a pH of 2.5 or lower, wherein the used sanitary product includes pulp fibers and a superabsorbent polymer; and applying a mechanical force to the used sanitary product during the degrading.

10 . The method of claim 9 , wherein the acid solution comprises an organic acid.

11 . The method of claim 9 , further comprising separating pulp fibers and pulp fibers in which superabsorbent polymers remain from the mixture formed in the degrading step to obtain separated pulp fibers.

12 . The method of claim 11 , further comprising treating the separated pulp fibers in an ozone-containing solution.

13 . The method of claim 12 , further comprising incorporating the treated pulp fibers into the sanitary product.

14 . The method of claim 13 , wherein incorporating the treated pulp fibers into the sanitary product comprises incorporating the treated pulp fibers into at least one of a disposable diaper, an incontinence pad, a urine collection pad, a sanitary napkin or a panty liner.

15 . The method of claim 12 , wherein treating the separated pulp fibers comprises producing treated pulp fibers having an ash content of 0.65% by weight or less.

16 . The method of claim 9 , wherein the used sanitary product includes organic waste.

17 . A method of extracting pulp fibers, the method comprising:
degrading the used sanitary product in an acid solution having a pH of 2.5 or lower, wherein the used sanitary product includes the pulp fibers and a superabsorbent polymer; and applying a mechanical force to the used sanitary product during the degrading.

18 . The method of claim 17 , wherein the acid solution comprises an organic acid.

19 . The method of claim 17 , further comprising separating pulp fibers and pulp fibers in which superabsorbent polymers remain from the mixture formed in the degrading step to obtain separated pulp fibers.

20 . The method of claim 19 , further comprising treating the separated pulp fibers in an ozone-containing solution.

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

• D21C5/022 Primary

  Chemicals therefor · CPC title