Method for production of particulate water absorbent comprising water-absorbable resin as main ingredient

• US 8,424,786 B2
• Filed: 03/13/2009
• Issued: 04/23/2013
• Est. Priority Date: 03/13/2008
• Status: Active Grant

• Current Assignee: Nippon Shokubai Company Limited
• Original Assignee: Nippon Shokubai Company Limited
• Inventors: Ishizaki, Kunihiko, Matsumoto, Koji, Mitsukami, Yoshiro
• Primary Examiner(s): Rosenbaum, Mark
• Application Number:
  US12/921,946
• Publication Number:
  US 20110006140A1
• Time in Patent Office: 1,502 Days
• Field of Search: 241/30, 241/29, 241/23, 241/25
• US Class Current: 241/23
• CPC Class Codes: B01J 20/26 Synthetic macromolecular compounds
• CPC Class Codes: B01J 20/267 Cross-linked polymers
• CPC Class Codes: B01J 20/30 Processes for preparing, regenerating, or reactivating
• CPC Class Codes: B01J 2220/68 Superabsorbents
• CPC Class Codes: B29B 2009/125 Micropellets, microgranules, microparticles
• CPC Class Codes: B29B 7/002 Methods chemical aspects C08J3/00
• CPC Class Codes: B29B 7/48 with intermeshing devices, e.g. screws
• CPC Class Codes: B29B 7/726 Measuring properties of mixture, e.g. temperature or density B29B7/724 takes precedence
• CPC Class Codes: B29B 7/748 Plants B29B7/7433, B29B7/7485, B29B7/7495 take precedence
• CPC Class Codes: B29B 7/82 Heating or cooling
• CPC Class Codes: B29B 7/885 with means for treating, e.g. milling, the charges B29B7/905 takes precedence
• CPC Class Codes: B29B 9/02 by dividing preformed material
• CPC Class Codes: B29B 9/12 characterised by structure or composition
• CPC Class Codes: B29B 9/16 Auxiliary treatment of granules
• CPC Class Codes: B65B 1/06 by gravity flow
• CPC Class Codes: B65B 1/08 by vibratory feeders
• CPC Class Codes: B65B 1/22 by vibration
• CPC Class Codes: B65B 37/04 by vibratory feeders
• CPC Class Codes: C08F 20/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08J 3/245 Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking

Abstract

[PROBLEM]

To obtain a particulate water absorbent having excellent and stabilized physical properties.

[SOLUTION]

One example of the production method for particulate water-absorbing agent of the present invention includes a polymerization step for polymerizing a monomer to obtain a polymer gel, a drying step for drying the polymer gel to obtain a particulate water-absorbing resin, a pulverization step for pulverizing the particulate water-absorbing resin, a classification step for sieving the particulate water-absorbing resin, a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin to obtain the particulate water-absorbing agent, a packaging step for filling the particulate water-absorbing agent into a packaging material container for packaging, and a transportation step for transporting the products produced in each of the steps to the other steps, wherein at least any one of the steps including and subsequent to the drying step is in two or more lines, for one line of the polymerization step.

Claims

1. A method for producing a particulate water-absorbing agent comprising:

a polymerization step for polymerizing a monomer to obtain a polymer gel;

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

a pulverization step for pulverizing the particulate water-absorbing resin;

a classification step for sieving the particulate water-absorbing resin;

a surface cross-linking step for cross-linking the neighborhood of the surface of the particulate water-absorbing resin to obtain a particulate water-absorbing agent;

a packaging step for filling the particulate water-absorbing agent into a packaging material container for packaging; and

a transportation step for transporting the products produced in each of the steps to the other steps;

wherein at least any one of the steps including and subsequent to the drying step is in two or more lines for one line of the polymerization step, in which two or more units of the same apparatus are installed in parallel for one unit of a polymerization apparatus.

2. The method for producing the particulate water-absorbing agent according to claim 1, wherein the pulverization step is in two or more lines, for one line of the polymerization step.

3. The method for producing the particulate water-absorbing agent according to claim 1, wherein the classification step is in two or more lines, for one line of the polymerization step.

4. The method for producing the particulate water-absorbing agent according to claim 1, wherein the steps from the polymerization step to before the pulverization step are in one line, while the pulverization step and the classification step are in two or more lines, for the one line.

5. The method for producing the particulate water-absorbing agent according to claim 1, further comprising a storing step, wherein the water-absorbing resin via the branched plural lines is collected in the storing step to become in one line.

6. The method for producing the particulate water-absorbing agent according to claim 5, wherein the storing step is performed at a temperature in the range of 40 to 150°

C.

7. The method for producing the particulate water-absorbing agent according to claim 1, wherein two or more cycles are performed, where a step in one line is branched to plural lines and then becomes in one line.

8. The method for producing the particulate water-absorbing agent according to claim 1, wherein the production amount of the particulate water-absorbing agent is equal to or more than 500 kg/h.

9. The method for producing the particulate water-absorbing agent according to claim 1, wherein the surface cross-linking step is in two or more lines, for one line of the polymerization step.

10. The method for producing the particulate water-absorbing agent according to claim 1, wherein all of the pulverization step, the classification step and the surface cross-linking step are in two or more lines, for one line of the polymerization step.

11. The method for producing the particulate water-absorbing agent according to claim 1, comprising a division step of the particulate water-absorbing resin.

12. The method for producing the particulate water-absorbing agent according to claim 1, comprising a division step for dividing the particulate water-absorbing resin to two portions in a ratio of 6:

4 to 4;

6.

13. The method for producing the particulate water-absorbing agent according to claim 1, wherein the particulate water-absorbing resin is divided after storage into a hopper.

14. The method for producing the particulate water-absorbing agent according to claim 1, wherein the particulate water-absorbing resin is divided in free fall.

15. The method for producing the particulate water-absorbing agent according to claim 1, wherein the particulate water-absorbing resin is divided in transporting to a plurality of hoppers by pneumatic transportation.

16. The method for producing the particulate water-absorbing agent according to claim 1, comprising a division step for dividing the polymer gel obtained in the polymerization step to two portions in a ratio of 6:

4 to 4;

6.

17. The method for producing the particulate water-absorbing agent according to claim 1, wherein the polymer gel obtained in the polymerization step is dried after being divided to two portions in free fall or by a feeder.

18. The method for producing the particulate water-absorbing agent according to claim 1, wherein the particle of the particulate water-absorbing resin is an irregular crushed particle, and said particulate water-absorbing resin is a polyacrylic acid (salt)-based water-absorbing resin.

19. The method for producing the particulate water-absorbing agent according to claim 1, wherein continuous kneader polymerization or continuous belt polymerization is performed in the polymerization step.

20. The method for producing the particulate water-absorbing agent according to claim 1, wherein the surface cross-linking step is performed using a surface cross-linking agent having dehydration esterification reactivity, of one or more kinds selected from an oxazolidinone compound, an alkylene carbonate compound, a polyvalent alcohol compound, and an oxetane compound, at a temperature in the range of 150 to 250°

C.

21. The method for producing the particulate water-absorbing agent according to claim 1, wherein the particulate water-absorbing agent has properties of CRC:

10 to 100 g/g, AAP;

15 to 50 g/g, SFC;

equal to or higher than 1 (unit;

10<sup>−

7</sup>·

cm³·

s·

g<sup>−

1</sup>), and the amount of fine powders with a particle diameter of below 150 μ

m;

0 to 5% by mass.