Method for recovering pulp fiber from used sanitary product and recycled pulp obtained thereby

Patent metadata

Field	Value
Publication number	US-2017284021-A1
Application number	US-201515512443-A
Country	US
Kind code	A1
Filing date	Aug 7, 2015
Priority date	Sep 22, 2014
Publication date	Oct 5, 2017
Grant date	—

Abstract

Pulp fiber containing little ash is effectively recovered from a used sanitary product containing the pulp fiber and a polymer absorbent. The method according to the present invention comprises: a step for treating the used sanitary product with an ozone-containing gas and thus decomposing and removing at least a portion of the polymer absorbent in the used sanitary product; and a step for stirring the used sanitary product, that has been treated with the ozone-containing gas, in water or an aqueous solution containing an antiseptic and thus decomposing the used sanitary product into constituents. If required, the method may further comprise a step for separating the pulp fiber from the decomposition product obtained by the decomposition step.

First claim

1 : A method for recovering pulp fiber from a used sanitary product including pulp fiber and a polymer absorbent, comprising the steps of:
treating the used sanitary product with an ozone-containing gas to decompose and remove at least a portion of the polymer absorbent in the used sanitary product, and stirring the used sanitary product that has been treated with the ozone-containing gas, in a disinfectant-containing aqueous solution or in water to decompose the used sanitary product into its constituent elements.

2 : The method according to claim 1 , wherein the ozone concentration of the ozone-containing gas is 50 to 200 g/m 3 .

3 : The method according to claim 1 , wherein the treatment time with the ozone-containing gas is 10 to 60 minutes.

4 : The method according to claim 1 , wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

5 : The method according to claim 1 , wherein the disinfectant is sodium hypochlorite, chlorine dioxide, acidic electrolyzed water, ozone water, acidic ozone water or organic acid-containing ozone water.

6 : The method according to claim 1 , further comprising a step of separating the pulp fiber from the decomposition product obtained by the decomposing step.

7 : The method according to claim 1 , comprising a step of separating apart at least a portion of the elements composing the used sanitary product and/or breaking up a portion of the used sanitary product before the step of treating the used sanitary product with an ozone-containing gas to decompose and remove at least a portion of the polymer absorbent in the used sanitary product.

8 : The method according to claim 1 , further comprising a step of drying the pulp fiber, the step of drying the pulp fiber resulting in dried pulp fiber having a moisture content of 5 to 13%.

9 : The method according to claim 8 , wherein the pulp fiber is dried at a temperature of 100 to 200° C.

10 : Recycled pulp having an ash content of not more than 0.8 percent by weight and a water absorption factor of not less than 12 times, obtained by a method for recovering pulp fiber from a used sanitary product including pulp fiber and a polymer absorbent, the method comprising the steps of:
treating the used sanitary product with an ozone-containing gas to decompose and remove at least a portion of the polymer absorbent in the used sanitary product, and stirring the used sanitary product that has been treated with the ozone-containing gas, in a disinfectant-containing aqueous solution or in water to decompose the used sanitary product into its constituent elements.

11 : Recycled pulp according to claim 10 , having an ash content of not more than 0.65 percent by weight.

12 : Recycled pulp according to claim 10 , having a moisture content of 5 to 13%.

13 : The method according to claim 2 , wherein the treatment time with the ozone-containing gas is 10 to 60 minutes

14 : The method according to claim 2 , wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

15 : The method according to claim 3 , wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

16 : The method according to claim 13 , wherein the used sanitary product is treated with the ozone-containing gas to decompose and remove at least 90% of the polymer absorbent in the used sanitary product.

17 : The method according to claim 2 , wherein the disinfectant is sodium hypochlorite, chlorine dioxide, acidic electrolyzed water, ozone water, acidic ozone water or organic acid-containing ozone water.

18 : The method according to claim 3 , wherein the disinfectant is sodium hypochlorite, chlorine dioxide, acidic electrolyzed water, ozone water, acidic ozone water or organic acid-containing ozone water

19 : The method according to claim 13 , wherein the disinfectant is sodium hypochlorite, chlorine dioxide, acidic electrolyzed water, ozone water, acidic ozone water or organic acid-containing ozone water

20 : The method according to claim 4 , wherein the disinfectant is sodium hypochlorite, chlorine dioxide, acidic electrolyzed water, ozone water, acidic ozone water or organic acid-containing ozone water.

Assignees

• Unicharm Corp

Inventors

• Konishi Takayoshi
• Hiraoka Toshio
• Kameda Noritomo
• Ichiura Hideaki
• Nakaoka Hiroko

Classifications

• B29L2031/4878

  Diapers, napkins · CPC title

• B29B2017/0289

  Washing the materials in liquids · CPC title

• D21B1/32

  of waste paper · CPC title

• B29B17/02

  Separating plastics from other materials · CPC title

• C08J11/16

  by treatment with inorganic material (C08J11/14 takes precedence) · CPC title