PROCESS FOR PRODUCTION OF WATER-ABSORBING RESINS

• US 20110028670A1
• Filed: 03/26/2009
• Published: 02/03/2011
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Matsumoto, Koji, Ishizaki, Kunihiko, Nogi, Kozo
• Granted Patent: US 8,410,223 B2
• Time in Patent Office: Days
• US Class Current: 526/317.1
• 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

There is provided a production method for a water-absorbing resin for stably and continuously producing the water-absorbing resin with industrially high property, in particular, the water-absorbing resin with high liquid permeation. A method of the present invention relates to a production method for a water-absorbing resin including: a polymerization step of an aqueous solution of an unsaturated monomer; a drying step of the resultant hydrogel polymer; and a surface cross-linking step after drying; characterized by including a pneumatic transportation step for pneumatic transporting the water-absorbing resin powder substance in a pipeline with a surface roughness (Rz) of the inner surface of equal to or smaller than 800 nm, by using gas with a dew point of −5° C. to −100° C.

Claims

1. A production method for a water-absorbing resin comprising:

a polymerization step for polymerizing an aqueous solution of an unsaturated monomer to obtain a hydrogel polymer;

a drying step for drying the hydrogel polymer to obtain a particulate water-absorbing resin; and

a surface cross-linking step for surface cross-linking the particulate water-absorbing resin;

wherein comprised is a pneumatic transportation step for pneumatic transporting a water-absorbing resin powder substance generated in each step in a pipeline with a surface roughness (Rz) of the inner surface of equal to or smaller than 800 nm, by using gas with a dew point of −

5°

C. to −

100°

C.

2. The production method according to claim 1, wherein the water-absorbing resin is a polyacrylic acid (salt)-based water-absorbing resin.

3. The production method according to claim 1, wherein the water-absorbing resin comprises a surfactant or a lubricant.

4. The production method according to claim 1, wherein the water-absorbing resin powder substance comprises a fine-powder recycled substance of the water-absorbing resin.

5. The production method according to claim 1, wherein the water-absorbing resin comprises a water-soluble polyvalent metal salt or a water-insoluble fine particle.

6. The production method according to claim 1, wherein dew point of the gas in dried state is 30°

C. to 100°

C.

7. The production method according to claim 1, wherein polymerization in the polymerization step is aqueous solution polymerization with a continuous belt or a continuous kneader.

8. The production method according to claim 1, wherein the water-absorbing resin powder substance satisfies at least one of absorbency against non-pressure (GV)≧

25 g/g, absorbency against pressure (AAP)≧

15 g/g and saline flow conductivity (SFC) for 0.69% by mass normal saline solution ≧

10 (×

10<sup>−

7</sup>·

cm³·

s·

g<sup>−

1</sup>).

9. The production method according to claim 1, comprising a dust collection step for removing the water-absorbing resin fine powder with a membrane filter at the same time as pneumatic transportation.

10. The production method according to claim 1, comprising the pneumatic transportation step after the surface cross-linking step.

11. The production method according to claim 1, comprising a step for storing the water-absorbing resin powder substance, after the pneumatic transportation step.

12. The production method according to claim 1, wherein a production capacity of the water-absorbing resin is a continuous production of equal to or higher than 1000 kg/hr.

13. The production method according to claim 1, wherein the surface cross-linking step is performed with a cross-linking agent having dehydration esterification reactivity.

14. The production method according to claim 2, wherein the water-absorbing resin comprises a surfactant or a lubricant.

15. The production method according to claim 2, wherein the water-absorbing resin powder substance comprises a fine-powder recycled substance of the water-absorbing resin.

16. The production method according to claim 3, wherein the water-absorbing resin powder substance comprises a fine-powder recycled substance of the water-absorbing resin.

17. The production method according to claim 14, wherein the water-absorbing resin powder substance comprises a fine-powder recycled substance of the water-absorbing resin.

18. The production method according claim 2, wherein the water-absorbing resin comprises a water-soluble polyvalent metal salt or a water-insoluble fine particle.

19. The production method according to claim 3, wherein the water-absorbing resin comprises a water-soluble polyvalent metal salt or a water-insoluble fine particle.

20. The production method according to claim 4, wherein the water-absorbing resin comprises a water-soluble polyvalent metal salt or a water-insoluble fine particle.