US4078135A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of suspension polymers of tetrafluoroethylene
Assignee: Hoechst AG
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Filing: 1976-05-20
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Granted: 1978-03-07
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Expires: 1996-05-20
Abstract
Abstract Polymers of tetrafluoroethylene are produced by suspension polymerization in the presence of small amounts of definite perfluorinated ethers. The products obtained have improved processing properties.
Inventors
- 👤 Reinhard Sulzbach
- 👤 Jurgen Kuhls
- 👤 Herbert Fitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:34
CPC Classifications
C; C08; C08F; C08F214/00; C08F214/18; C08F214/26; C08F214/262
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
71 words
In the process of polymerizing tetrafluoroethylene by the suspension process in the presence of a usual catalyst and optionally buffer substances, precipitating agents, small amounts of emusifiers and heavy metal salts, the improvement which comprises conducting the suspension polymerization in the presence of from 0.0004 to 0.0029 mol %, calculated on the tetrafluoroethylene used, of at least one perfluorinated ether having the formula: ##STR6## in which n is 1 to 4.
Claim 2
Dependent Claim
71 words
In the process of polymerizing tetrafluoroethylene by the suspension process in the presence of a usual catalyst and optionally buffer substances, precipitating agents, small amounts of emusifiers and heavy metal salts, the improvement which comprises conducting the suspension polymerization in the presence of from 0.0004 to 0.0029 mol %, calculated on the tetrafluoroethylene used, of at least one perfluorinated ether having the formula: ##STR6## in which n is 1 to 4.
Claim 3
Dependent Claim
31 words
The process as claimed in claim 1, wherein the perfluorinated ether is present during the suspension polymerization in an amount of from 0.001 to 0.0020 mol %, calculated on tetrafluoroethylene used.
Claim 4
Dependent Claim
14 words
The process as claimed in claim 1, wherein n stands for 1 or 2.
Claim 5
Dependent Claim
43 words
In the method of producing shaped articles of modified polytetrafluoroethylene by molding, sintering and ram extruding modified polytetrafluoroethylene the improvement of obtaining shaped articles free from cracks which comprises molding, sintering and ram extruding modified polytetrafluoroethylene obtained by the process of claim 1.
References Cited (Backward Citations)
US3450684A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-03-06 | 1981-09-05 | 1982-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-06 | 1985-09-05 | 1986-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-06 | 1989-09-05 | 1990-03-07 | $7700.00 | Window Closed / Lapsed |