Patent US2453117A successfully refreshed from Google Patents.
Patent US4243781A successfully refreshed from Google Patents.
US4243781A
Expired / Lapsed
US
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Process for the preparation of styrene and acrylonitrile containing polymers
Assignee: Dow Chemical Co
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Filing: 1979-06-25
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Granted: 1981-01-06
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Expires: 1999-06-25
Abstract
Abstract A process is disclosed for the preparation of styrene and acrylonitrile containing polymers wherein styrene and acrylonitrile in a predetermined ratio are introduced continuously into a recirculating polymerization zone of generally constant composition wherein a portion of the styrene and acrylonitrile is polymerized, material is removed from the polymerization zone at a rate equal to the addition of styrene and acrylonitrile on removal from the polymerization zone the monomer being separated from the resulting polymer, the improvement being maintaining a level of oxygen in the styrene and acrylonitrile not greater than 20 parts per million by weight based on the weight of the styrene and acrylonitrile. The resultant polymer is generally colorless.
Inventors
- 👤 Raymond W. Kent, Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:48
CPC Classifications
C; C08; C08F; C08F212/00; C08F212/02; C08F212/04; C08F212/06; C08F212/08; C08F212/10; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
135 words
In a method for the preparation of styrene and acrylonitrile containing polymers wherein sytrene and acrylonitrile are introduced into a recirculating polymerization zone to form a polymerizing mass, the polymerizing mass being of generally constant composition, removing a portion of the polymerizing mass from the polymerization zone, separating volatile components from the mass to thereby recover a styrene and acrylonitrile containing polymer therefrom and returning at least a portion of the volatile components to the polymerization zone, the improvement which comprises maintaining a level of oxygen in feed to the polymerizing zone at a level not greater than 20 parts by weight per million parts by weight of the polymerizing mass wherein the styrene and acrylonitrile prior to entering polymerization zone are sparged with nitrogen and/or are passed through a vacuum chamber to remove oxygen.
Claim 2
Dependent Claim
135 words
In a method for the preparation of styrene and acrylonitrile containing polymers wherein sytrene and acrylonitrile are introduced into a recirculating polymerization zone to form a polymerizing mass, the polymerizing mass being of generally constant composition, removing a portion of the polymerizing mass from the polymerization zone, separating volatile components from the mass to thereby recover a styrene and acrylonitrile containing polymer therefrom and returning at least a portion of the volatile components to the polymerization zone, the improvement which comprises maintaining a level of oxygen in feed to the polymerizing zone at a level not greater than 20 parts by weight per million parts by weight of the polymerizing mass wherein the styrene and acrylonitrile prior to entering polymerization zone are sparged with nitrogen and/or are passed through a vacuum chamber to remove oxygen.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the oxygen level is not greater than 5 parts per million parts by weight of the polymerizing mass.
Claim 4
Dependent Claim
24 words
The method of claim 1 wherein the oxygen level is not greater than 2 parts per million parts by weight of the polymerizing mass.
Claim 5
Dependent Claim
32 words
The method of claim 1 wherein styrene is present in a proportion of 20 to 98 parts by weight and acrylonitrile present in amount from about 2 to 80 parts by weight.
Claim 6
Dependent Claim
32 words
The method of claim 1 wherein styrene is present in a proportion of 80 to 65 parts by weight and acrylonitrile present in amount from about 20 to 35 parts by weight.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the styrene and acrylonitrile prior to entering polymerization zone are sparged with nitrogen to remove oxygen.
Claim 8
Dependent Claim
25 words
The method of claim 1 wherein the styrene and acrylonitrile are passed through a vacuum chamber prior to entering polymerization zone to remove oxygen therefrom.
Claim 9
Dependent Claim
136 words
In a method for the preparation of styrene and acrylonitrile containing polymers and the styrene and acrylonitrile are introduced into a recirculating polymerization zone to form a polymerizing mass, the polymerizing mass being of generally constant composition, removing a portion of the polymerizing mass from the polymerization zone, separating volatile components from the mass to thereby recover a styrene and acrylonitrile containing polymer therefrom and returning at least a portion of the volatile components to the polymerization zone, the improvement which comprises maintaining a level of oxygen in feed to the polymerizing zone at a level not greater than 5 parts by weight per million parts by weight of the polymerizing mass wherein the styrene and acrylonitrile prior to entering polymerization zone are sparged with nitrogen and/or are passed through a vacuum chamber to remove oxygen.
Claim 10
Dependent Claim
136 words
In a method for the preparation of styrene and acrylonitrile containing polymers and the styrene and acrylonitrile are introduced into a recirculating polymerization zone to form a polymerizing mass, the polymerizing mass being of generally constant composition, removing a portion of the polymerizing mass from the polymerization zone, separating volatile components from the mass to thereby recover a styrene and acrylonitrile containing polymer therefrom and returning at least a portion of the volatile components to the polymerization zone, the improvement which comprises maintaining a level of oxygen in feed to the polymerizing zone at a level not greater than 5 parts by weight per million parts by weight of the polymerizing mass wherein the styrene and acrylonitrile prior to entering polymerization zone are sparged with nitrogen and/or are passed through a vacuum chamber to remove oxygen.
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) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |