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EP0533192A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Process for preparing highly water absorbent resin

Assignee: LG Corp
•
Filing: 1992-09-18
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Granted: —
•
Expires: 2012-09-18
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Abstract

Abstract The present invention provides an improved process for preparing a highly water absorbent resin having a superior suction power and excellent gel strength, which comprises: (1) dehydrating a polymer, which is prepared by partially neutralizing monomers or polymers containing a carboxyl or carboxylate group and polymerizing them, by using an azeotropic distillation method in the presence of a lipophilic solvent; (2) crosslinking the dehydrated polymer in the presence of a hydrophilic crosslinking agent and dehydrating the crosslinked polymer by using an azeotropic distillation method; and (3) filtering and drying the reaction products to recover the crosslinked polymer, wherein the improvement comprises: (a) in step(1), the polymer is dehydrated until it has a water content of 25% by weight or less based on the weight of the polymer; and, (b) in step(2), water is employed to penetrate the hydrophilic crosslinking agent into the intraparticle in an amount ranging from 7.0 to 25.0% by weight based on the weight of the polymer, for the crosslinking process and an amount of 60% by weight or more based on the added amount of water is removed from the crosslinked polymer during the dehydration process.

Inventors

  • 👤 Jang Tae-Hwan
  • 👤 Choi Su-Beom
  • 👤 Lee Hyung-Mann
  • 👤 Kim Myung-Joong

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-25 13:37
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/24; C08J2300/00; C08J2300/14

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 176 words
An improved process for preparing a water absorbent resin, which comprises: (1) dehydrating a polymer, which is prepared by partially neutralizing monomers or polymers containing a carboxyl or carboxylate group and polymerizing them, by using an azeotropic distillation method in the presence of a lipophilic solvent; (2) crosslinking the dehydrated polymer in the presence of a hydrophilic crosslinking agent and dehydrating the crosslinked polymer by using an azeotropic distillation method; and (3) filtering and drying the reaction products to recover the crosslinked polymer, wherein the improvement comprises: (a) in step(1), the polymer is dehydrated until it has a water content of 25% by weight or less based on the weight of the polymer; and, (b) in step(2), water is employed to penetrate the hydrophilic crosslinking agent into the intraparticle in an amount ranging from 7.0 to 25.0% by weight based on the weight of the polymer, for the crosslinking process and an amount of 60% by weight or more based on the added amount of water is removed from the crosslinked polymer during the dehydration process.
Claim 2
Dependent Claim 16 words
The process of claim 1 wherein an alkali metal hydroxide is employed for the partial neutralization.
Claim 3
Dependent Claim 25 words
The process of claim 1 wherein the lipophilic solvent employed is selected from the group consisting of n-hexane, n-heptane, benzene, xylene, toluene, cyclopentane and cyclohexane.
Claim 4
Dependent Claim 28 words
The process of claim 1 wherein the crosslinking agent is employed in an amount ranging from 0.05 to 5.0% by weight based on the weight of the polymer.
Claim 5
Dependent Claim 54 words
The process of claim 1 which further comprises, between step(2) and step(3), a secondary crosslinking of the crosslinked polymer in the presence of a mixture of a hydrophilic crosslinking agent and a hydrophilic solvent after having removed the lipophilic solvent and a dehydration of the secondarily crosslinked polymer by using an azeotropic distillation method.
Claim 6
Dependent Claim 33 words
The process of claim 1 or 5 wherein the crosslinking agent is selected from the group consisting of ethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylol propane polyglycidyl ether and sorbitol polyglycidyl ether.
Claim 7
Dependent Claim 34 words
The process of claim 5 wherein the crosslinking agent is employed in an amount ranging from 0.5 to 5.0% by weight based on the weight of the polymer used for the secondary crosslinking process.
Claim 8
Dependent Claim 11 words
The process of claim 5 wherein the hydrophilic solvent is methanol.
Claim 9
Dependent Claim 30 words
The process of claim 5 wherein the hydrophilic solvent is employed in an amount ranging from 1.7 to 2.7 parts by weight per one part by weight of the polymer.

References Cited (Backward Citations)

EP0083022A2 Cited
GB2126591A Cited
US5032628A Cited

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