Patent US4551228A successfully refreshed from Google Patents.
US3669940A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-step bulk polymerization of pivalolactone
Assignee: Shell USA Inc
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Filing: 1969-10-09
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Granted: 1972-06-13
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Expires: 1989-10-09
Abstract
Abstract Between 50 and 85 per cent of a beta-lactone such as pivalolactone is bulk polymerized in an initial reactor at a maximum temperature of 300* C. The polymerization is then continued in at least one subsequent reactor. Preferably, the reactors are gear pumps.
Inventors
- 👤 Paul J A Desgurse
- 👤 Harm P Rogaar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:13
CPC Classifications
C; C08; C08G; C08G63/00; C08G63/78; C08G63/785; C08G63/82; C08G63/823
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
17 words
A process according to claim 1, characterized in that said initial reaction zone comprises a gear pump.
Claim 2
Dependent Claim
30 words
A process according to claim 1, characterized in that said beta-lactone supplied to said initial reaction zone has been cooled to a temperature of between -15* C. and +10* C.
Claim 3
Dependent Claim
26 words
A process according to claim 1, characterized in that the temperature of the beta-lactone in the first reaction zone is maintained between 250* and 300* C.
Claim 4
Dependent Claim
27 words
A process according to claim 1, characterized in that in the first reaction zone between 60 and 85 percent of the beta-lactone is polymerized in said zone.
Claim 5
Dependent Claim
13 words
A process according to claim 1, characterized in that the beta-lactone is alpha,alpha,dimethyl-beta-propiolactone.
References Cited (Backward Citations)
NL264931A
Cited
GB1090780A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-13 | 1975-12-13 | 1976-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-13 | 1979-12-13 | 1980-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-13 | 1983-12-13 | 1984-06-13 | $7700.00 | Window Closed / Lapsed |