A method for recovering superabsorbent polymers from components containing superabsorbent polymers that make up used sanitary products, and a method for producing recycled superabsorbent polymers using the recovered superabsorbent polymers.

Abstract

To provide a method for improving the recovery rate and purity of superabsorbent polymers in a method for recovering superabsorbent polymers from constituent materials containing superabsorbent polymers that constitute used sanitary products.SOLUTION: The method for recovering the superabsorbent polymers from constituent materials containing superabsorbent polymers that constitute used sanitary products includes a preparation process S30 to prepare agglomerate in a wet state containing the constituent materials containing the inactivated superabsorbent polymers and a separation process S20 to separate the superabsorbent polymers from the constituent materials by applying vibration to the agglomerate.SELECTED DRAWING: Figure 1

Claims

1. A method for recovering a superabsorbent polymer from a component material containing a superabsorbent polymer that constitutes a used sanitary product, A preparation step of preparing a wet aggregate having a moisture content of 10 to 85% by mass, which contains the constituent material including the superabsorbent polymer that has been inactivated and dehydrated by immersing the superabsorbent polymer in an aqueous solution containing an inactivating agent, A separation step of applying vibration to the aggregate to separate the superabsorbent polymer from the constituent material, It is equipped with, The preparation step includes an inactivation step for inactivating the superabsorbent polymer, The inactivation step is, A pre-dehydration step is performed by immersing the constituent material in an acidic aqueous solution as an inactivating agent to pre-dehydrate the superabsorbent polymer in the constituent material, A dehydration step is performed by bringing the constituent material into contact with a polyvalent metal ion source capable of supplying polyvalent metal ions as an inactivator, thereby dehydrating the superabsorbent polymer in the constituent material. Having, method.

2. The separation step includes a sieving separation step in which the aggregates are subjected to a vibrating sieve having mesh through which the superabsorbent polymer can pass. The method according to claim 1.

3. The preparation step includes a solid-liquid separation step in which solid-liquid separation is performed on an aqueous solution containing the constituent material which includes the inactivated superabsorbent polymer, to obtain the aggregate which is a solid and a liquid. The method according to claim 2.

4. The solid-liquid separation step includes a centrifugation step in which an aqueous solution containing the constituent materials is centrifuged to obtain the aggregate and the liquid. The method according to claim 3.

5. The moisture content of the superabsorbent polymer separated in the centrifugal separation step is 80% by mass or less. The method according to claim 4.

6. Below the centrifugal separator that performs the centrifugal separation step, a sieving device having the sieve for the sieving separation step is positioned. The method according to claim 4.

7. The method further comprises a step of recovering the superabsorbent polymer from the liquid obtained in the solid-liquid separation step by screening. The method according to claim 3.

8. In the aforementioned sieve separation step, the vibration of the sieve includes transverse vibration. The method according to claim 2.

9. The aforementioned sieve is, A first sieve portion having an opening through which the superabsorbent polymer can pass, A second sieve portion is located below the first sieve portion and has a finer mesh than the first sieve portion, allowing the superabsorbent polymer to pass through. Equipped with, The aforementioned sieving separation step is The process includes passing the aggregates through a vibrating sieve, thereby separating the superabsorbent polymer in two stages: the first sieve portion and the second sieve portion. The method according to claim 2 or 8.

10. The aforementioned constituent material includes pulp fibers, The sieving separation step includes the steps of separating the pulp fibers from each other by moving outward on the surface of the sieve and the superabsorbent polymer by moving downward on the sieve. The method according to claim 2 or 8.

11. The method further comprises a reactivation step in which the superabsorbent polymer obtained in the separation step is reactivated by contacting it with an alkali metal ion source capable of supplying alkali metal ions. The method according to claim 1 or 2.

12. A method for producing recycled superabsorbent polymers, A step of carrying out a method for recovering the superabsorbent polymer according to claim 1 or 2, The method for recovering the superabsorbent polymer includes a reactivation step in which the superabsorbent polymer obtained by the method is reactivated by contacting it with an alkali metal ion source capable of supplying alkali metal ions. method.

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