US4497930A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing highly water absorptive polymer
Assignee: Kao Corp
•
Filing: 1983-08-26
•
Granted: 1985-02-05
•
Expires: 2003-08-26
Abstract
Abstract A highly water absorbent polymer having high resistance to salt solution is prepared by crosslinking a hyrophilic polymer or copolymer having carboxyl and/or carboxylate groups and water content of 10 to 40 wt. % with a crosslinking agent having at least two functional groups capable of reaction with said carboxyl and carboxylate group. An improved hydrophilic polymer is produced by polymerizing a monomer with a persulfate and a hydroperoxide as combined initiators. Another improved hydrophilic polymer is prepared by polymerizing a monomer with a persulfate and adding a hydroperoxide to the resulting polymer.
Inventors
- 👤 Harumasa Yamasaki
- 👤 Takatoshi Kobayashi
- 👤 Yuzo Sumida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:46
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/24; A; A61; A61L; A61L15/00; A61L15/16; A61L15/42; A61L15/60; C08J2300/00; C08J2300/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
102 words
A process for producing a highly water absorbent polymer, which comprises: polymerizing a hydrophilic, carboxylic acid monomer or salt thereof, which monomer is dissolved in water, to obtain a hydrous hydrophilic polymer; then dehydrating said hydrous hydrophilic polymer until the water content thereof is from 10 to 40 wt.%, based on the total amount of said hydrous hydrophilic polymer, then adding to said hydrous hydrophilic polymer an effective amount of a crosslinking agent having at least two functional groups in the molecule, which functional groups are capable of reacting with carboxyl and carboxylate groups, and effecting crosslinking of said hydrous hydrophilic polymer.
Claim 2
Dependent Claim
102 words
A process for producing a highly water absorbent polymer, which comprises: polymerizing a hydrophilic, carboxylic acid monomer or salt thereof, which monomer is dissolved in water, to obtain a hydrous hydrophilic polymer; then dehydrating said hydrous hydrophilic polymer until the water content thereof is from 10 to 40 wt.%, based on the total amount of said hydrous hydrophilic polymer, then adding to said hydrous hydrophilic polymer an effective amount of a crosslinking agent having at least two functional groups in the molecule, which functional groups are capable of reacting with carboxyl and carboxylate groups, and effecting crosslinking of said hydrous hydrophilic polymer.
Claim 3
Dependent Claim
26 words
A process as claimed in claim 1 in which, in said dehydrating step, the water content of said polymer is reduced to 15 to 35 wt.%.
Claim 4
Dependent Claim
26 words
A process as claimed in claim 1 in which said crosslinking agent is selected from the group consisting of polyglycidyl ethers, haloepoxy compounds, polyaldehydes and polyamines.
Claim 5
Dependent Claim
16 words
A process as claimed in claim 1 in which said crosslinking agent is a polyglycidyl ether.
Claim 6
Dependent Claim
79 words
A process as claimed in claim 1 in which, in said polymerizing step, said monomer is polymerized in the presence of both a persulfate polymerization initiator and a hydroperoxide polymerization initiator, the amount of said persulfate polymerization initiator being in the range of from 0.01 to 1.0 wt.%, based on the weight of said monomer, and the amount of said hydroperoxide initiator being in the range of from 0.01 to 2.0 wt.%, based on the weight of said monomer.
Claim 7
Dependent Claim
78 words
A process as claimed in claim 1 in which, in said polymerizing step, said monomer is polymerized in the presence of from 0.01 to 1.0 wt.%, based on the weight of said monomer, of a persulfate polymerization initiator, and thereafter but prior to said dehydrating step, adding to said polymer from 0.005 to 2.0 wt.%, based on the weight of said monomer, of a hydroperoxide polymerization initiator and then aging the polymerization mixture before performing said dehydrating step.
Claim 8
Dependent Claim
33 words
A process as claimed in claim 1 in which said polymerizing step is reversed phase suspension polymerization wherein droplets of the solution of the monomer in water are suspended in an oil medium.
Claim 9
Dependent Claim
30 words
A process as claimed in claim 1 in which the amount of said crosslinking agent is from 0.01 to 5 wt.%, based on the weight of said hydrous hydrophilic polymer.
Claim 10
Dependent Claim
34 words
A process as claimed in claim 1, claim 5 or claim 6 in which said monomer is selected from the group consisting of acrylic acid, methacrylic acid and alkali metal salts of said acids.
Claim 11
Dependent Claim
42 words
A process as claimed in claim 1, claim 5 or claim 6 in which said monomer is sodium acrylate and said crosslinking agent is selected from the group consisting of ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and glycerol diglycidyl ether.
Claim 12
Dependent Claim
39 words
A process as claimed in claim 1, claim 5 or claim 6 in which in said crosslinking step, the mixture of said hydrous hydrophilic polymer and said crosslinking agent is heated to a temperature of 40° to 150° C.
References Cited (Backward Citations)
US3847851A
Cited
US4135943A
Cited
US4059552A
Cited
US3929741A
Cited
US4093776A
Cited
US4179367A
Cited
US4367323A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |