US4384092A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of polytetrafluoroethylene
Assignee: Produits Chimiques Ugine Kuhlmann
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Filing: 1981-04-24
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Granted: 1983-05-17
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Expires: 2001-04-24
Abstract
Abstract A treatment procedure for aqueous colloidal polytetrafluoroethylene dispersions obtained by polymerization of tetrafluoroethylene in the presence of the lithium salt of a perfluoroalkanesulfonic acid as the emulsifier, characterized by the fact that a basic hydroxide or a soluble ammonium, alkali metal or alkaline-earth salt, with the exception of lithium hydroxide or a lithium salt, is added to the dispersion.
Inventors
- 👤 Jean Blaise
- 👤 Jean-Louis Herisson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:04
CPC Classifications
C; C08; C08F; C08F6/00; C08F6/14
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
In the method of making polytetrafluoroethylene by polymerization of tetrafluoroethylene in the presence of a lithium salt of a perfluoroalkanesulfonic acid as the emulsifier to form an aqueous colloidal dispersion of the polymer, the improvement comprising adding to the dispersion after the polymerization is completed an electrolyte in an amount sufficient to displace the cation of the emulsifier entirely selected from a basic hydroxide or a soluble ammonium, alkali metal, or alkaline earth salt, other than lithium hydroxide or a lithium salt.
Claim 2
Dependent Claim
82 words
In the method of making polytetrafluoroethylene by polymerization of tetrafluoroethylene in the presence of a lithium salt of a perfluoroalkanesulfonic acid as the emulsifier to form an aqueous colloidal dispersion of the polymer, the improvement comprising adding to the dispersion after the polymerization is completed an electrolyte in an amount sufficient to displace the cation of the emulsifier entirely selected from a basic hydroxide or a soluble ammonium, alkali metal, or alkaline earth salt, other than lithium hydroxide or a lithium salt.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the basic hydroxide is an alkali metal hydroxide.
Claim 4
Independent Claim
21 words
The method of claims 1 or 2 wherein the electrolyte is added to the dispersion prior to coagulation of the dispersion.
Claim 5
Independent Claim
25 words
The method of claims 1 or 2 wherein the electrolyte is added in an amount sufficient at least stoichiometrically equivalent to the amount of emulsifier.
Claim 6
Independent Claim
18 words
The method of claims 1 and 2 wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.
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) | 1986-05-16 | 1986-11-15 | 1987-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-16 | 1990-11-15 | 1991-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-16 | 1994-11-15 | 1995-05-17 | $7700.00 | Window Closed / Lapsed |