US4216265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aftertreatment of thermally pretreated tetrafluoroethylene polymers and the polymer powders obtained
Assignee: Hoechst AG
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Filing: 1978-09-27
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Granted: 1980-08-05
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Expires: 1998-09-27
Abstract
Abstract In a process for aftertreating thermally presintered polymers of tetrafluoroethylene the optionally comminuted powders are subjected, at temperatures below +80° C., to the action of a gas jet mill. Preferred starting materials are tetrafluoroethylene polymers containing a small proportion of a modifying monomer. By the aftertreatment the bulk density and the flow index of the powders are considerably improved without a noticeable disintegration taking place. The aftertreated powders are used in the first place for the manufacture of shaped articles in extrusion devices with automatic feeding means.
Inventors
- 👤 Reinhard A. Sulzbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:13
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/12; B; B29; B29B; B29B13/00; B29B13/10; C08F; C08F6/00; C08F6/06; C08F6/10; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
70 words
A process for preparing improved powders of non-melt-processable tetrafluoroethylene polymers, which comprises exposing a presintered powder of said-non-melt-processable tetrafluoroethylene polymer which is presintered to a degree of sintering of substantially 100% as determined by differential thermoanalysis, to an impact stress effected substantially solely by interparticulate collisions caused by the action of high velocity gas jets in a jet mill thereby increasing the bulk density and reducing the powder flow index.
Claim 2
Dependent Claim
70 words
A process for preparing improved powders of non-melt-processable tetrafluoroethylene polymers, which comprises exposing a presintered powder of said-non-melt-processable tetrafluoroethylene polymer which is presintered to a degree of sintering of substantially 100% as determined by differential thermoanalysis, to an impact stress effected substantially solely by interparticulate collisions caused by the action of high velocity gas jets in a jet mill thereby increasing the bulk density and reducing the powder flow index.
Claim 3
Dependent Claim
18 words
The process of claim 1, wherein said presintered powder is a homopolymer of tetrafluoroethylene obtained by suspension polymerization.
Claim 4
Dependent Claim
37 words
The process of claim 1, wherein said presintered powder is a tetrafluoroethylene polymer obtained by suspension polymerization of tetrafluoroethylene in the presence of from 0.0004 to 1.5 mol percent, calculated on tetrafluoroethylene, of a modifying perfluorinated monomer.
Claim 5
Dependent Claim
83 words
The process of claim 3, wherein said modifying perfluorinated monomer is a perfluoro(alkyl vinyl)ether of the formula CF.sub.2 ═CF--O--R.sub.f, wherein R f is a perfluoroalkyl group having from 1 to 4 C atoms, a perfluorinated ether of the formula ##STR3## wherein n is 0 or 1, a perfluorinated ether of the formula ##STR4## wherein n is 1 or 2, perfluoro-2-methylene-4-methyl-1,3-dioxolane, or a perfluorinated olefin of the formula CF.sub.2 ═CF--R.sub.f, wherein R f is a perfluoroalkyl group having from 1 to 4 C atoms.
Claim 6
Dependent Claim
36 words
The process as claimed in claim 3, wherein said modifying monomer is CF 2 ═CF--OC 3 F 7 , CF 2 ═CF--O--CF 2 --CF(CF 3 )--O--C 3 F 7 , CF 2 ═CF--CF 3 or ##STR5##
Claim 7
Dependent Claim
15 words
The process as claimed in claim 1 wherein said presintered powder contains an inorganic filler.
Claim 8
Dependent Claim
91 words
A presintered powder of non-melt-processable tetrafluoroethylene powder composed of, in polymerized form, tetrafluoroethylene and from 0.0002 to 0.5 mol percent, calculated on tetrafluoroethylene, of a perfluorinated modifying monomer, having a degree of sintering of substantially 100% as determined by differential thermo-analysis, an average particle diameter d 50 of from 200 to 900 μum with no more than 15% by weight of particles with a diameter below 150 μum, a bulk density of more than 770 grams per liter and a powder flow index not higher than 3 seconds per 50 grams.
Claim 9
Dependent Claim
91 words
A presintered powder of non-melt-processable tetrafluoroethylene powder composed of, in polymerized form, tetrafluoroethylene and from 0.0002 to 0.5 mol percent, calculated on tetrafluoroethylene, of a perfluorinated modifying monomer, having a degree of sintering of substantially 100% as determined by differential thermo-analysis, an average particle diameter d 50 of from 200 to 900 μum with no more than 15% by weight of particles with a diameter below 150 μum, a bulk density of more than 770 grams per liter and a powder flow index not higher than 3 seconds per 50 grams.
Claim 10
Dependent Claim
110 words
A presintered powder of non-melt-fabricable tetrafluoroethylene as claimed in claim 7, which is composed of, in polymerized form, tetrafluoroethylene and from 0.0002 to 0.5 mol percent, calculated on tetrafluoroethylene, of a member selected from the group consisting of a perfluro(alkyl vinyl)ether of the formula CF.sub.2 ═CF--O--R.sub.f, wherein R f is a perfluoroalkyl group having from 1 to 4 C atoms, a perfluorinated ether of the formula ##STR6## wherein n is 0 or 1, a perfluorinated ether of the formula ##STR7## wherein n is 1 or 2, perfluoro-2-methylene-4-methyl-1,3-dioxolane, or a perfluorinated olefin of the formula CF.sub.2 ═CF--R.sub.f, wherein R f is a perfluoroalkyl group having from 1 to 4 C atoms.
Claim 11
Dependent Claim
62 words
A presintered powder of non-melt-processable tetrafluoroethylene as claimed in claim 7, which is composed of, in polymerized form, tetrafluoroethylene and from 0.0002 to 0.5 mol percent, calculated on tetrafluoroethylene, of a member selected from the group consisting of CF 2 ═CF--OC 3 F 7 , CF 2 ═CF--O--CF 2 --CF(CF 3 )--O--C 3 F 7 , CF 2 ═CF--CF 3 or ##STR8##
References Cited (Backward Citations)
US2989777A
Cited
US3087921A
Cited
US3152201A
Cited
US3331825A
Cited
US3527857A
Cited
US3419522A
Cited
US3532782A
Cited
US3528955A
Cited
US3726483A
Cited
US3911072A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-08-05 | 1984-02-04 | 1984-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-08-05 | 1988-02-04 | 1988-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-08-05 | 1992-02-04 | 1992-08-05 | $7700.00 | Window Closed / Lapsed |