TRANSPORT METHOD FOR ABSORBEND RESIN POWDER

• US 20110110730A1
• Filed: 03/26/2009
• Published: 05/12/2011
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Nakamura, Masatoshi, Awai, Kazuma, Matsumoto, Koji, Nogi, Kozo
• Granted Patent: US 9,096,732 B2
• Time in Patent Office: Days
• US Class Current: 406/197
• CPC Class Codes: C08F 6/008 Treatment of solid polymer wetted by water or organic solvents, e.g. coagulum, filter cakes
• CPC Class Codes: C08J 2333/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08J 3/075 Macromolecular gels
• CPC Class Codes: C08J 3/12 Powdering or granulating
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking

Abstract

[Problem] To provide a pneumatic conveyance method for a water-absorbing resin powder substance, which is capable of suppressing property decrease of the water-absorbing resin powder substance, while suppressing obstruction phenomenon.

[Solution] A conveyance method for a water-absorbing resin powder substance by pneumatic conveyance of the water-absorbing resin powder substance during a production step via a transportation pipeline, wherein a variation of a solid-gas ratio (R1/R2) exceeds 1 and is equal to or smaller than 7, provided that R1 (kg-resin/kg-air) stands for an initial solid-gas ratio at a start point of the transportation pipeline, and R2 (kg-resin/kg-air) stands for a terminal solid-gas ratio at a terminal point of the transportation pipeline is provided.

Claims

1. A conveyance method for a water-absorbing resin powder substance by pneumatic conveyance of the water-absorbing resin powder substance during a production step via a transportation pipeline,

wherein a variation of a solid-gas ratio (R1/R2) exceeds 1 and is equal to or smaller than 7, provided that R1 (kg-resin/kg-air) stands for an initial solid-gas ratio at a start point of the transportation pipeline, and R2 (kg-resin/kg-air) stands for a terminal solid-gas ratio at a terminal point of the transportation pipeline.

2. The conveyance method according to claim 1, wherein a linear velocity of the water-absorbing resin powder substance at the start point of the transportation pipeline (initial linear velocity) is equal to or lower than 7 m/s.

3. The conveyance method according to claim 1, wherein the initial solid-gas ratio R1 is 35 to 150 (kg-resin/kg-air).

4. The conveyance method according to claim 1, wherein the terminal solid-gas ratio R2 is 20 to 50 (kg-resin/kg-air).

5. The conveyance method according to claim 1, wherein at least a part of the transportation pipeline is kept heated at a temperature equal to or higher than 50°

C. by heating from outside.

6. The conveyance method according to claim 1, wherein a production apparatus performing the production step comprises a storage part, and the storage part is kept heated at a temperature equal to or higher than 50°

C. by heating from outside.

7. The conveyance method according to claim 6, wherein the water-absorbing resin powder substance pneumatically conveyed is stored in the storage part.

8. The conveyance method according to claim 1, wherein total length Lt of the transportation pipeline included in one transportation section is equal to or larger than 50 m.

9. The conveyance method according to claim 1, wherein the pneumatic conveyance is high density pneumatic conveyance.

10. The conveyance method according to claim 1, wherein amount of the conveyed water-absorbing resin powder substance is equal to or higher than 1000 kg/hr.

11. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance is surface cross-linked with a polyhydric alcohol.

12. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance comprises a polyvalent metal salt.

13. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance comprises an inorganic particle.

14. The conveyance method according to claim 1, wherein a saline flow conductivity (SFC) for 0.69% by mass normal saline solution of the water-absorbing resin powder substance after conveyance is equal to or larger than 10(×

10<sup>−

7</sup>·

cm³·

s·

g<sup>−

1</sup>).

15. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance is a polyacrylic acid (salt)-based water-absorbing resin with an irregular and fractured shape, obtained by continuous belt polymerization or continuous kneader polymerization.

16. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance is a polyacrylic acid (salt)-based water-absorbing resin obtained by a production step comprising a fine-powder recycling step.

17. The conveyance method according to claim 1, wherein the water-absorbing resin powder substance is a polyacrylic acid (salt)-based water-absorbing resin formed by surface cross-linking at 150 to 250°

C.

18. The conveyance method according to claim 2, wherein the initial solid-gas ratio R1 is 35 to 150 (kg-resin/kg-air).

19. The conveyance method according to claim 2, wherein the terminal solid-gas ratio R2 is 20 to 50 (kg-resin/kg-air).

20. The conveyance method according to claim 3, wherein the terminal solid-gas ratio R2 is 20 to 50 (kg-resin/kg-air).