Patent US4766188A successfully refreshed from Google Patents.
US4766188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of tetrafluoroethylene polymers
Assignee: Asahi Glass Fluoropolymers USA Inc
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Filing: 1987-11-09
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Granted: 1988-08-23
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Expires: 2007-11-09
Abstract
Abstract Production of coagulated dispersion grades of PTFE using an aqueous emulsion polymerization process which employs an initiator system comprising disuccinic acid peroxide and ammonium sulphite, the latter being added during the course of the polymerization. The resulting polymer can be fabricated into porous products of improved properties.
Inventors
- 👤 Terence E. Attwood
- 👤 Richard F. Bridges
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 10:02
CPC Classifications
C; C08; C08F; C08F114/00; C08F114/18; C08F114/26; C08F14/00; C08F14/18; C08F14/26
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
100 words
Process for the production of a coagulated dispersion grade tetrafluoroethylene homo- or copolymer which process comprises emulsion polymerising tetrafluoroethylene, and optionally one or more comonomers, in an aqueous medium in the presence of a surfactant(s) as emulsifying agent and a water-soluble initiator system comprising disuccinic acid peroxide and ammonium sulphite, the ammonium sulphite being added to the aqueous reaction medium after the start of polymerisation, namely at a conversion within the range 1 to 95%, and the amount of ammonium sulphite employed being within the range 25 to 300% by weight, based on the weight of disuccinic acid peroxide used.
Claim 2
Dependent Claim
100 words
Process for the production of a coagulated dispersion grade tetrafluoroethylene homo- or copolymer which process comprises emulsion polymerising tetrafluoroethylene, and optionally one or more comonomers, in an aqueous medium in the presence of a surfactant(s) as emulsifying agent and a water-soluble initiator system comprising disuccinic acid peroxide and ammonium sulphite, the ammonium sulphite being added to the aqueous reaction medium after the start of polymerisation, namely at a conversion within the range 1 to 95%, and the amount of ammonium sulphite employed being within the range 25 to 300% by weight, based on the weight of disuccinic acid peroxide used.
Claim 3
Dependent Claim
26 words
Process according to claim 1 wherein the amount of disuccinic acid peroxide employed is 0.002 to 0.08% by weight based on the weight of water charged.
Claim 4
Dependent Claim
25 words
Process according to either claim 1 or claim 2 wherein the ammonium sulphite is added when the conversion is within the range 5 to 80%.
Claim 5
Dependent Claim
25 words
Process according to either claim 1 or claim 2 wherein the ammonium sulphite is added when the conversion is within the range 90 to 95%.
Claim 6
Dependent Claim
30 words
Process according to claim 1 wherein the amount of ammonium sulphite employed is within the range 25 to 150% by weight, based on the weight of disuccinic acid peroxide used.
Claim 7
Dependent Claim
16 words
Process according to claim 1 wherein the ammonium sulphite used is added in a single charge.
Claim 8
Dependent Claim
23 words
Process according to any one of claims 1 to 5 wherein the ammonium sulphite used is added in 2 or more separate charges.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |