Method for producing water-absorbent resin powder, and drying device and drying method for particulate hydrous gel

Patent metadata

Field	Value
Publication number	US-11766659-B2
Application number	US-201716349758-A
Country	US
Kind code	B2
Filing date	Nov 16, 2017
Priority date	Nov 16, 2016
Publication date	Sep 26, 2023
Grant date	Sep 26, 2023

Abstract

The production method includes a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles. The heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container. A gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50° C.

First claim

The invention claimed is:

1. A method for producing water-absorbent resin powder, the method comprising
a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer aqueous solution containing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles, wherein
the heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container, and
a gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50° C.

2. The method according to claim 1 , wherein a heat medium of 150° C. or higher is supplied to the heating tubes.

3. The method according to claim 1 , wherein a temperature of an inner surface of the rotary container is not lower than 150° C.

4. The method according to claim 1 , wherein a temperature of an inner surface of the rotary container is set to be not lower than 150° C. before the particulate crosslinked hydrogel polymer is put inside.

5. The method according to claim 1 , wherein a gas is introduced as a heat medium into the rotary container, and a temperature of an inner surface of the rotary container is higher than a temperature of the gas.

6. The method according to claim 5 , wherein the temperature of the gas to be introduced into the rotary container is not lower than 100° C.

7. The method according to claim 1 , further comprising a cooling step of cooling the dried particles.

8. The method according to claim 1 , wherein, in the drying step, an additive is added during heating drying of the particulate crosslinked hydrogel polymer contained in the rotary container.

9. The method according to claim 8 , wherein the additive is a surface-crosslinking agent.

10. The method according to claim 1 , wherein the particulate crosslinked hydrogel polymer contains a gel fluidizer.

11. The method according to claim 1 , wherein the gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step is 60 to 120° C.

12. The method according to claim 1 , wherein a particle diameter d 1 of the particulate crosslinked hydrogel polymer to be subjected to the drying step is not greater than 800 μm.

13. The method according to claim 1 , wherein steam of 0.49 MPa or greater is introduced into the plurality of heating tubes.

14. The method according to claim 1 , wherein a Froude number Fr of the heating device is 0.001 to 1.

15. The method of claim 1 , wherein the heating device comprises not less than five of the heating tubes.

16. The method of claim 1 , wherein the heating device comprises a heating means or a thermal insulating means on an outer peripheral surface of the rotary container.

17. The method of claim 1 , wherein the rotary container is inclined from one end toward another end of the rotary container.

18. The method of claim 1 , wherein the rotary container comprises at least one obstructive wall within the rotary container.

19. The method of claim 1 , wherein the heating device has a ratio of a heat transfer area to an effective capacity of the rotary container (heat transfer area/effective capacity) of not less than 10 m −1 , wherein the heat transfer area is a sum of surface areas of outer peripheral surfaces of the heating tubes and an area of an inner peripheral surface of the rotary container.

Assignees

• Nippon Catalytic Chem Ind

Inventors

• Watabe Hiroyasu
• Sato Mai
• Wakabayashi Ryota
• Shobo Yoshihiro
• Katsube Shin-Ya
• Imura Motohiro
• Honda Koji
• Fujino Shin-Ichi
• Ishizaki Kunihiko
• SHUTO Tokio

Classifications

• B01J20/267 Primary

  Cross-linked polymers · CPC title

• B01J13/0065

  containing an organic phase · CPC title

• B01J13/0069

  Post treatment · CPC title

• B01J20/28004

  Sorbent size or size distribution, e.g. particle size · CPC title

• B01J20/28016

  Particle form · CPC title