Patent US3915944A successfully refreshed from Google Patents.
US3915944A
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Prevention of polymer build up in reactors used for vinyl chloride polymerization
Assignee: European Vinyls Corp Technology AG
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Filing: 1973-11-12
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Granted: 1975-10-28
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Expires: 1993-11-12
Abstract
Abstract Vinyl chloride is polymerised in aqueous dispersion, preferably in aqueous suspension, in the presence of a polymeric imine such as polyethylene imine, the pH of the reaction medium being maintained at or above 4 by a buffering mixture or an alkaline substance. The process enables the production of vinyl chloride polymers with a minimum of polymer build-up on the walls of the polymerisation reactor.
Inventors
- 👤 Robin Henry Burgess
- 👤 Richard William Tomlinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:59
CPC Classifications
C; C08; C08F; C08F14/00; C08F14/02; C08F14/04; C08F14/06
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
96 words
A PROCESS FOR THE PRODUCTION OF VINYL CHLORINE POLYMERS WHICH COMPRSES POLYMERISING UNDER CNDITIONS OF VIGOROUS AGITATION VINYL CHLORIDE, OR VINYL CHLORIDE AND UP TO 20 PERCENT BY WEIGHT THEREOF OF AT LEAST ONE ETHYLENICALLY UNSATURATED MONOMER COPOLYMERISABLE THEREWITH, IN AQUEOUS DISPERSION, IN THE PRESENCE OF A POLYMERIC IMINE SELECTED FROM THE GROUP CONSISTING OF POLYMERIC ETHYLENE IMINE AND POLYMERIC SUBSTITUTED ETHYLENE IMINES WHEREIN THE SUBSTITUTION IS ESSENTIALLY INERT TO THE VINYL CHLORIDE POLYMERISATION, THE PH OF THE POLYMERISATION MEDIUM BEING MAINTAINED AT AT LEAST 4 FOR ALL OR FOR A SUBSTANTIAL PERIOD OF THE POLYMERISATION.
Claim 2
Dependent Claim
96 words
A PROCESS FOR THE PRODUCTION OF VINYL CHLORINE POLYMERS WHICH COMPRSES POLYMERISING UNDER CNDITIONS OF VIGOROUS AGITATION VINYL CHLORIDE, OR VINYL CHLORIDE AND UP TO 20 PERCENT BY WEIGHT THEREOF OF AT LEAST ONE ETHYLENICALLY UNSATURATED MONOMER COPOLYMERISABLE THEREWITH, IN AQUEOUS DISPERSION, IN THE PRESENCE OF A POLYMERIC IMINE SELECTED FROM THE GROUP CONSISTING OF POLYMERIC ETHYLENE IMINE AND POLYMERIC SUBSTITUTED ETHYLENE IMINES WHEREIN THE SUBSTITUTION IS ESSENTIALLY INERT TO THE VINYL CHLORIDE POLYMERISATION, THE PH OF THE POLYMERISATION MEDIUM BEING MAINTAINED AT AT LEAST 4 FOR ALL OR FOR A SUBSTANTIAL PERIOD OF THE POLYMERISATION.
Claim 3
Dependent Claim
11 words
A process according to claim 1 which is a batch polymerisation.
Claim 4
Dependent Claim
16 words
A process according to claim 1 in which the polymerisation is carried out in aqueous suspension.
Claim 5
Dependent Claim
15 words
A process according to claim 1 in which the polymeric imine used is polyethylene imine.
Claim 6
Dependent Claim
45 words
A process according to claim 1 in which at least part of the polymeric imine is incorporated into the polymerisation medium by applying a solution thereof onto the reactor wall before charging the aqueous medium and the ingredients for the polymerisation reaction to the reactor.
Claim 7
Dependent Claim
28 words
A process according to claim 1 in which at least part of the polymeric imine is incorporated into the polymerisation medium by charging it to the aqueous medium.
Claim 8
Dependent Claim
40 words
A process according to claim 6 in which the amount of polymeric imine added to the aqueous medium lies within the range 10 to 200 parts per million, based on the weight of the vinyl chloride used in the polymerisation.
Claim 9
Dependent Claim
24 words
A process according to claim 6 in which the amount of polymeric imine used lies within the range 20 to 80 parts per million.
Claim 10
Dependent Claim
28 words
A process according to claim 1 in which the pH of the polymerisation medium is maintained at at least 4 by the addition of an alkaline substance thereto.
Claim 11
Dependent Claim
28 words
A process according to claim 9 in which the alkaline substance is selected from the group consisting of the hydroxides, carbonates and bicarbonates of sodium, calcium and ammonium.
Claim 12
Dependent Claim
27 words
A process according to claim 1 in which the pH of the polymerisation medium is maintained at at least 4 by the use of a buffering mixture.
Claim 13
Dependent Claim
18 words
A process according to claim 11 in which the buffering mixture comprises disodium orthophosphate and monosodium hydrogen orthophosphate.
References Cited (Backward Citations)
US3515709A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |