Patent US4017445A successfully refreshed from Google Patents.
US4017445A
Expired / Lapsed
US
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Process for the removal of vinyl chloride from polyvinyl chloride dispersions
Assignee: Huels AG
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Filing: 1975-08-28
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Granted: 1977-04-12
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Expires: 1995-08-28
Abstract
Abstract Residual vinyl chloride contents of aqueous polyvinyl chloride dispersions is reduced to less than 50 ppm by withdrawing steam and vinyl chloride contained in a boiling aqueous polyvinyl chloride dispersion at a temperature of 80 DEG -100 DEG C. and at a vaporization rate per minute of 0.006-0.2 kg. steam per kg. of polyvinyl chloride for a period of time from 3-60 minutes until a vinyl chloride content of less than 50 p.p.m. is achieved.
Inventors
- 👤 Hans Grosse-Wortmann
- 👤 Bernhard Hentschel
- 👤 Peter Rauth
- 👤 Karl-Heinz Schoenberg
- 👤 Bernd Terwiesch
- 👤 Hermann Winter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:50
CPC Classifications
C; C08; C08F; C08F6/00; C08F6/14; C08F6/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
94 words
In a process for the removal with steam of unreacted vinyl chloride, from aqueous polyvinyl chloride dispersions obtained by suspension or emulsion polymerizations of vinyl chloride, to residual monomer contents of less than 50 p.p.m., the improvement which comprises withdrawing steam and vinyl chloride contained in a boiling aqueous polyvinyl chloride dispersion maintained at a temperature of 80°-100° C., at a vaporization rate per minute of 0.006-0.2 kg steam per kg of polyvinyl chloride, for a period of time from 3-60 minutes until a vinyl chloride content of less than 50 p.p.m. is achieved.
Claim 2
Dependent Claim
94 words
In a process for the removal with steam of unreacted vinyl chloride, from aqueous polyvinyl chloride dispersions obtained by suspension or emulsion polymerizations of vinyl chloride, to residual monomer contents of less than 50 p.p.m., the improvement which comprises withdrawing steam and vinyl chloride contained in a boiling aqueous polyvinyl chloride dispersion maintained at a temperature of 80°-100° C., at a vaporization rate per minute of 0.006-0.2 kg steam per kg of polyvinyl chloride, for a period of time from 3-60 minutes until a vinyl chloride content of less than 50 p.p.m. is achieved.
Claim 3
Dependent Claim
17 words
A process according to claim 1 wherein the dispersion is maintained at 80°-100° C. by indirect heating.
Claim 4
Dependent Claim
28 words
A process according to claim 1, wherein the steam and vinyl chloride are withdrawn at a vaporization rate per minute of 0.05-0.2 kg per kg of polyvinyl chloride.
Claim 5
Dependent Claim
60 words
A continuous process according to claim 1, which comprises preheating a stream of the aqueous polyvinyl chloride dispersion to 80°-100° C in a heating zone, bringing a stream of heated dispersion to its boiling point by adjusting the vapor pressure thereof, transferring a stream of the boiling dispersion to a degasification zone, and passing steam countercurrently through the dispersion therein.
Claim 6
Dependent Claim
24 words
A process according to claim 4, wherein a partial stream of the dispersion discharged from the degasification zone is recycled to the heating zone.
Claim 7
Dependent Claim
28 words
A process according to claim 4, wherein the steam and vinyl chloride are withdrawn at a vaporization rate per minute of 0.05-0.2 kg per kg of polyvinyl chloride.
Claim 8
Dependent Claim
26 words
A process according to claim 1 wherein the dispersion is maintained at 80°-100° C. by both indirect heating and by introduction of steam into the dispersion.
Claim 9
Dependent Claim
14 words
A process according to claim 1 wherein the dispersion is maintained at 90° C.
Claim 10
Dependent Claim
14 words
A process according to claim 1 wherein the dispersion is maintained at 100° C.
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) | 1980-04-11 | 1980-10-11 | 1981-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-11 | 1984-10-11 | 1985-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-11 | 1988-10-11 | 1989-04-12 | $7700.00 | Window Closed / Lapsed |