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US5202400A
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Process for the production of highly water absorptive polymers
Assignee: Mitsubishi Chemical Corp
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Filing: 1991-08-19
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Granted: 1993-04-13
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Expires: 2011-08-19
Abstract
Abstract A process for producing a highly water absorptive polymer by polymerizing a water-soluble, ethylenically unsaturated monomer in a water-in-oil type of dispersion consisting of the dispersion phase of an aqueous monomer solution comprising the water-soluble, ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and an optional water-soluble crosslinking agent and the continuous phase of an organic solvent containing a dispersant, characterized in that the aqueous monomer solution is added to the organic solvent at such a temperature as to form an oil-in-water type of dispersion, and the oil-in-water type of dispersion is then heated at least to a phase reversal temperature at which it is transformed into the water-in-oil type of dispersion.
Inventors
- 👤 Kiichi Itoh
- 👤 Shuhei Yada
- 👤 Kenji Yoshinaga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:44
CPC Classifications
C; C08; C08F; C08F2/00; C08F2/32
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
112 words
A process for producing a highly water absorptive polymer by polymerizing a water-soluble, ethylenically unsaturated monomer in a water-in-oil type of dispersion consisting of the dispersion phase of an aqueous monomer solution comprising the water-soluble, ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and an optional water-soluble crosslinking agent and the continuous phase of an organic solvent containing a dispersant, characterized in that said aqueous monomer solution is added to said organic solvent at such a temperature as to form an oil-in-water type of dispersion, and the oil-in-water type of dispersion is then heated at least to a phase reversal temperature at which it is transformed into said water-in-oil type of dispersion.
Claim 2
Dependent Claim
112 words
A process for producing a highly water absorptive polymer by polymerizing a water-soluble, ethylenically unsaturated monomer in a water-in-oil type of dispersion consisting of the dispersion phase of an aqueous monomer solution comprising the water-soluble, ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and an optional water-soluble crosslinking agent and the continuous phase of an organic solvent containing a dispersant, characterized in that said aqueous monomer solution is added to said organic solvent at such a temperature as to form an oil-in-water type of dispersion, and the oil-in-water type of dispersion is then heated at least to a phase reversal temperature at which it is transformed into said water-in-oil type of dispersion.
Claim 3
Dependent Claim
34 words
The process according to claim 1, wherein the water-soluble, ethylenically unsaturated monomer comprises as a main component acrylic acid with 50-95% of the total carboxyl groups neutralized as an alkali metal or ammonium salt.
Claim 4
Dependent Claim
29 words
The process according to claim 1, wherein the concentration of the water-soluble, ethylenically unsaturated monomer in the aqueous monomer solution ranges from 20% by weight to the saturation concentration.
Claim 5
Dependent Claim
29 words
The process according to claim 1, wherein the organic solvent is an aliphatic or alicyclic hydrocarbon solvent and the dispersant is a nonionic surfactant with an HLB of 3-9.
Claim 6
Dependent Claim
21 words
The process according to claim 1, wherein the polymerization is carried out at 40°-100° C. for 30 minutes to 10 hours.
Claim 7
Dependent Claim
26 words
The process according to claim 1, wherein the temperature at which polymerization occurs of 30°-150° C. is greater than the phase reversal temperature of the process.
Claim 8
Dependent Claim
29 words
The process according to claim 1, wherein said water-soluble cross-linking agent is present in an amount ranging from 0.001 to 5% by weight based on the weight of monomer.
Claim 9
Dependent Claim
91 words
A process for producing a highly water-absorptive polymer, comprising: forming an aqueous monomer solution of a water-soluble, ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and an optional water-soluble crosslinking agent and adding the solution to an organic solvent at a temperature at which an oil-in-water dispersion is formed; heating the oil-in-water dispersion to a temperature sufficient to transform the dispersion into a water-in-oil dispersion; conducting polymerization of monomer in the water-in-oil dispersion in which the aqueous phase is dispersed in the continuous phase of the organic solvent containing a dispersant.
Claim 10
Dependent Claim
91 words
A process for producing a highly water-absorptive polymer, comprising: forming an aqueous monomer solution of a water-soluble, ethylenically unsaturated monomer, water, a water-soluble polymerization initiator and an optional water-soluble crosslinking agent and adding the solution to an organic solvent at a temperature at which an oil-in-water dispersion is formed; heating the oil-in-water dispersion to a temperature sufficient to transform the dispersion into a water-in-oil dispersion; conducting polymerization of monomer in the water-in-oil dispersion in which the aqueous phase is dispersed in the continuous phase of the organic solvent containing a dispersant.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-12 | 1996-10-12 | 1997-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-12 | 2000-10-12 | 2001-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-12 | 2004-10-12 | 2005-04-13 | $7700.00 | Window Closed / Lapsed |