Process for producing water-absorbing polyacrylic acid (salt) resin

Patent metadata

Field	Value
Publication number	US-2016279602-A1
Application number	US-201415036230-A
Country	US
Kind code	A1
Filing date	Nov 14, 2014
Priority date	Nov 14, 2013
Publication date	Sep 29, 2016
Grant date	—

Abstract

The purpose of the present invention is to provide a process for stably and continuously producing a water-absorbing resin, specifically, a process for stably and continuously producing a water-absorbing resin, the process including a gas absorbing step in which a gas discharged from a step of producing a water-absorbing resin is efficiently and persistently absorbed. A main point of this process for producing a water-absorbing polyacrylic acid (salt) resin further including a step of absorbing a gas discharged from a production step of the water-absorbing polyacrylic acid (salt) resin in water having a pH of 7 to 11 and a polyvalent metal ion content of 100 ppm or less or a step of absorbing the gas in water having a pH of 7 to 11, the pH of the water having been adjusted by mixing a water having an electric conductivity of 500 (μS/cm) or less at 25° C. with an alkali compound.

First claim

1 . A process for producing a water-absorbing polyacrylic acid (salt) resin including a step of absorbing a gas discharged from a production step of the water-absorbing polyacrylic acid (salt) resin in water having a pH of 7 to 11 and a polyvalent metal ion content of 100 ppm or less.

2 . The process according to claim 1 , wherein the polyvalent metal ion content is 10 ppm or less.

3 . The process according to claim 1 , wherein the polyvalent metal ion content is 1 ppm or less.

4 . The process according to claim 1 , wherein the polyvalent metal ion is an ion of elements in Group 2 of the periodic table.

5 . A process for producing a water-absorbing polyacrylic acid (salt) resin including a step of absorbing a gas discharged from a production step of the water-absorbing polyacrylic acid (salt) resin in water having a pH of 7 to 11, the pH of the water having been adjusted by mixing a water having an electric conductivity of 500 (μS/cm) or less at 25° C. with an alkali compound.

6 . The process according to claim 1 , wherein a temperature of the water is 30 to 100° C.

7 . The process according to claim 5 , wherein the alkali compound is at least one compound selected from the group consisting of a hydroxide, a carbonate or a hydrogen carbonate of an alkali metal.

8 . The process according to claim 1 , wherein a temperature of the gas discharged from the production step is 30 to 150° C. at the time the gas is introduced to an exhaust gas absorption tower.

9 . The process according to claim 1 , wherein the gas discharged from the production step contains a monomer.

10 . The process according to claim 1 , wherein the gas discharged from the production step is absorbed in the water under slightly reduced pressure.

11 . The process according to claim 1 , wherein the gas discharged from the production step is cooled by a heat exchanger for heat recovery.

12 . The process according to claim 11 , wherein the heat exchanger has a specific cooling power of 10 (W/cm 2 ) or less.

13 . The process according to claim 1 , wherein an absorbing liquid discharged from the absorbing step is collected for the production step of the polyacrylic acid (salt) water-absorbing resin.

14 . The process according to claim 1 , wherein an absorbing liquid discharged from the absorbing step is subjected to a combustion treatment.

15 . The process according to claim 1 , wherein an absorbing liquid discharged from the absorption step is subjected to a biological treatment.

16 . The process according to claim 1 , wherein an amount of the production of the water-absorbing polyacrylic acid (salt) resin is 1 (t/hr) or more per production line, and a continuous operation time of the process is 10 days or more.

17 . The process according to claim 1 , wherein a polyvalent metal is used in the production step of the water-absorbing polyacrylic acid (salt) resin.

18 . The process according to claim 1 , wherein the production step of the water-absorbing polyacrylic acid (salt) resin includes a step of polymerizing an aqueous acrylic acid (salt) monomer solution, a step of drying a hydrogel-forming crosslinked polymer, and a step of surface crosslinking a water absorbing resin powder.

19 . The process according to claim 18 , wherein a weight average particle size (D50) of the hydrogel-forming crosslinked polymer is 2000 μm or less.

20 . The process according to claim 18 , wherein the drying step is carried out by hot-air drying at a drying temperature of 100 to 300° C. and a wind speed of 3 (m/s) or less.

21 . The process according to claim 18 , wherein the gas discharged from the production step is discharged from the drying step.

22 . An apparatus for a water-absorbing resin in which an exhaust gas discharged from a production step of the water-absorbing polyacrylic acid (salt) resin is brought into gas-liquid contact with an absorbing liquid that neutralizes organic substances in said exhaust gas for removal of organic substances from the exhaust gas, the apparatus comprising:
a gas-liquid contact means for bringing the exhaust gas into gas-liquid contact with the absorbing liquid; a spray means for supplying the absorbing liquid from above the gas-liquid contact means to the gas-liquid contact means; an exhaust gas supplying means for supplying the exhaust gas from below the gas-liquid contact means; and a circulation passage for transferring the absorbing liquid retained below the gas-liquid contact means to the spray means, wherein the gas-liquid contact means is positioned for allowing the exhaust gas supplied from below the gas-liquid contact means to longitudinally pass through the gas-liquid contact means, wherein the spray means is positioned for the absorbing liquid to be downward toward the gas-liquid contact means, and wherein the circulation passage includes a means for forcedly circulating the absorbing liquid

23 . The process according to claim 5 , wherein a temperature of the water having a pH of 7 to 11 is 30 to 100° C.

24 . The process according to claim 5 , wherein a temperature of the gas discharged from the production step is 30 to 150° C. at the time the gas is introduced to an exhaust gas absorption tower.

25 . The process according to claim 5 , wherein the gas discharged from the production step contains a monomer.

26 . The process according to claim 5 , wherein the gas discharged from the production step is absorbed in the water having a pH of 7 to 11 under slightly reduced pressure

27 . The process according to claim 5 , wherein the gas discharged from the production step is cooled by a heat exchanger for heat recovery.

28 . The process according to claim 27 , wherein the heat exchanger has a specific cooling power of 10 (W/cm 2 ) or less.

29 . The process according to claim 5 , wherein an absorbing liquid discharged from the absorbing step is collected for the production step of the polyacrylic acid (salt) water-absorbing resin.

30 . The process according to claim 5 , wherein an absorbing liquid discharged from the absorbing step is subjected to a combustion treatment.

31 . The process according to claim 5 , wherein an absorbing liquid discharged from the absorption step is subjected to a biological treatment.

32 . The process according to claim 5 , wherein an amount of the production of the water-absorbing polyacrylic acid (salt) resin is 1 (t/hr) or more per production line, and a continuous operation time of the process is 10 days or more.

33 . The process according to claim 5 , wherein a polyvalent metal is used in the production step of the water-absorbing polyacrylic acid (salt) resin.

34 . The process according to claim 5 , wherein the production step of the water-absorbing polyacrylic acid (salt) resin includes a step of polymerizing an aqueous acrylic acid (salt) monomer solution, a step of drying a hydrogel-forming crosslinked polymer, and a step of surface crosslinking a water absorbing resin powder.

35 . The process according to claim 34 , wherein a weight average particle size (D50) of the hydrogel-forming crosslinked polymer is 2000 μm or less.

36 . The process according to claim 34 , wherein the drying step is carried out by hot-air drying at a drying

Assignees

• Nippon Catalytic Chem Ind

Inventors

• Nagasawa Makoto
• Sano Jiro
• Katada Yoshiki
• Ishizaki Kunihiko

Classifications

• B01D2252/10

  Inorganic absorbents · CPC title

• C08F20/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• C08F2/10

  Aqueous solvent · CPC title

• B01D53/1493

  Selection of liquid materials for use as absorbents · CPC title

• B01D53/1418

  Recovery of products · CPC title