Patent US4068052A successfully refreshed from Google Patents.
US4068052A
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Reducing PVC polymer buildup in polymerization reactors with dithioxamides and alumina
Assignee: VISTA POLYMERS Inc A DE CRP AND WHOLLY-OWNED SUBSIDIARY OF VISTA CHEMICAL Co
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Filing: 1976-06-23
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Granted: 1978-01-10
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Expires: 1996-06-23
Abstract
Abstract A method for preventing polymer buildup in the polymerization reactor during the suspension polymerization of vinyl chloride monomer to form polyvinyl chloride polymer and copolymers, the method comprising coating reactor surfaces in contact with the reaction medium with a material selected from the group consisting of alumina, dithiooxamide, and mixtures of these prior to carrying out this polymerization.
Inventors
- 👤 Dean Raymond Weimer
- 👤 Albert M. Durr, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:26
CPC Classifications
C; C08; C08F; C08F2/00; C08F2/002; C08F2/004
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
89 words
A method for preventing polymer buildup in a polymerization reactor during the suspension polymerization of vinyl chloride monomer to form polyvinyl chloride polymer and copolymer, the method comprising coating reactor surfaces in contact with the reaction medium with a material selected from the group consisting of a mixture of alumina and dithiooxamide prior to carrying out the polymerization, wherein said coating contains from about 1 to about 20 weight percent alumina and from about 0.05 to about 5 weight percent dithiooxamide, based on the total weight of the coating.
Claim 2
Independent Claim
89 words
A method for preventing polymer buildup in a polymerization reactor during the suspension polymerization of vinyl chloride monomer to form polyvinyl chloride polymer and copolymer, the method comprising coating reactor surfaces in contact with the reaction medium with a material selected from the group consisting of a mixture of alumina and dithiooxamide prior to carrying out the polymerization, wherein said coating contains from about 1 to about 20 weight percent alumina and from about 0.05 to about 5 weight percent dithiooxamide, based on the total weight of the coating.
Claim 3
Dependent Claim
22 words
A method as described in claim 1 wherein a base is added to the mixture prior to spraying onto the reactor interior.
Claim 4
Dependent Claim
13 words
A method as described in claim 2 wherein the base is sodium hydroxide.
Claim 5
Dependent Claim
27 words
A method as described in claim 2 wherein sufficient base is added to obtain a pH of 7 prior to spraying the mixture onto the reactor interior.
Claim 6
Dependent Claim
67 words
A method as described in claim 1 wherein the coating is prepared by dispersing alumina in a water solution in the presence of a dispersant selected from the group consisting of aluminum nitrate hydrate, ferric chloride, ferric chloride hexahydrate, soluble chormic chloride, chromic chloride hydrates, chromic nitrate hydrates, ferric nitrate hydrates, hydrochloric acid, nitric acid, acetic acid and chloroacetic acid, followed by stirring dithiooxamide into the dispersion.
Claim 7
Dependent Claim
37 words
A method as described in claim 1 wherein the dithiooxamide has the general formula: ##STR2##wherein R and R' are the same or different groups selected from the group consisting of 2-hydroxymethyl, carboxymethyl, benzyl, cyclohexyl, dodecyl and methyl.
Claim 8
Dependent Claim
27 words
A method as described in claim 1 wherein the alumina is in a concentration of from 0.1 to 2 weight percent, based on the total coating weight.
Claim 9
Dependent Claim
28 words
A method as described in claim 7, wherein sodium hydroxide is added to the coating in an amount sufficient to raise the pH of the coating to 7.
Claim 10
Dependent Claim
36 words
A method as described in claim 6 wherein substituted dithiooxamides selected from the group consisting of N,N'-bis (2-hydroxyethyl) dithiooxamide; N,N'-dibenzyl dithiooxamide; N,N'-dodecyl dithiooxamide, N,N'-dimethyl dithiooxamide and N,N'-dicyclohexyl dithiooxamide are used alone or in combination with dithiooxamide.
References Cited (Backward Citations)
GB1000348A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-09 | 1981-07-11 | 1982-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-09 | 1985-07-11 | 1986-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-09 | 1989-07-11 | 1990-01-10 | $7700.00 | Window Closed / Lapsed |