US3620991A
Expired / Lapsed
US
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Preparation of aqueous solution of acrylamide containing no free oxygen and polymerization of acrylamide therein
Assignee: Wyeth Holdings LLC
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Filing: 1968-09-25
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Granted: 1971-11-16
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Expires: 1988-09-25
Abstract
Abstract Dissolved molecular oxygen in aqueous solutions of acrylamide is inactivated without significant detriment to the acrylamide and to the solution as a polymerization medium, by adding a watersoluble metal sulfite and allowing the solution to stand at pH 48. If desired, excess sulfite can be decomposed without harm to the acrylamide by raising the pH of the solution above 8, and the acrylamide therein can be polymerized or copolymerized by conventional means.
Inventors
- 👤 Richard Barkman Wasser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 17:34
CPC Classifications
C; C08; C08F; C08F20/00; C08F20/02; C08F20/52
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
13 words
A process according to claim 1 wherein the ionizing sulfite is sodium bisulfite.
Claim 2
Dependent Claim
22 words
A process according to claim 1 wherein the weight of added sulfite is about 0.05 percent of the weight of the solution.
Claim 3
Dependent Claim
26 words
A process according to claim 1, wherein the pH of the solution is between 5.5 and 6.5 during conversion of said oxygen to chemically reacted form.
Claim 4
Dependent Claim
27 words
A process according to claim 1 wherein the solution is at a temperature between 0* C. and 30* C. during and subsequent to addition of said sulfite.
Claim 5
Dependent Claim
27 words
A process according to claim 1 wherein the aqueous solution contains between 5 and 10 mol percent of diallyl dimethyl ammonium chloride per mol of acrylamide therein.
Claim 6
Dependent Claim
24 words
A process according to claim 1 wherein the pH of the solution is further raised to 12 after it has been raised to 8.
Claim 7
Dependent Claim
146 words
A process for preparing an aqueous solution of a polyacrylamide from an aqueous solution comprising acrylamide and dissolved molecular oxygen, which consists essentially in adding a water-soluble ionizing sulfite to said solution in stoichiometric excess over the oxygen dissolved therein, excluding gaseous oxygen from access to said solution, allowing said solution to stand at a pH in the range of 5 to 8 for 10 to 60 minutes at 0* C. to 60* C. in accordance with claim 1, until substantially all of said oxygen has been converted to chemically reacted form, then elevating the pH of the solution above 8 and allowing the solution to stand at said elevated pH until the solution has substantially no content of sulfite, and then adding a vinyl polymerization catalyst and allowing said solution to stand until polymerization of at least a substantial part of said acrylamide has occured.
References Cited (Backward Citations)
US3278506A
Cited
US3365409A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |