US5064593A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing multilayer polytetrafluoroethylene porous membrane
Assignee: Daikin Industries Ltd
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Filing: 1990-12-06
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Granted: 1991-11-12
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Expires: 2010-12-06
Abstract
Abstract A process for producing a multilayer polytetrafluoroethylene porous membrane comprising at least two layers having different average pore diameters is disclosed, the process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; subsequently paste-extruding the powders to obtain a multilayer extrudate, which is then optionally rolled; and then stretching the extrudate or the rolled extrudate at least monoaxially after the liquid lubricant is removed therefrom or without removing the liquid lubricant.
Inventors
- 👤 Shinji Tamaru
- 👤 Katsutoshi Yamamoto
- 👤 Osamu Tanaka
- 👤 Hirofumi Nishibayashi
- 👤 Osamu Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:28
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/005; B01; B01D; B01D69/00; B01D69/12; B01D69/1212; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29C55/02; B29C55/023; B32; B32B; B32B37/00; C; C08; C08J; C08J9/00; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
94 words
A process for producing a multilayer polytetrafluoroethylene porous membrane comprising at least two layers having different average pore diameters, said process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; subsequently paste-extruding said powders to obtain a multilayer extrudate, which is then optionally rolled; and then stretching said extrudate or said rolled extrudate at least monoaxially after said liquid lubricant is removed therefrom or without removing said liquid lubricant.
Claim 2
Dependent Claim
94 words
A process for producing a multilayer polytetrafluoroethylene porous membrane comprising at least two layers having different average pore diameters, said process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; subsequently paste-extruding said powders to obtain a multilayer extrudate, which is then optionally rolled; and then stretching said extrudate or said rolled extrudate at least monoaxially after said liquid lubricant is removed therefrom or without removing said liquid lubricant.
Claim 3
Dependent Claim
29 words
A process as claimed in claim 1, wherein at least one of said polytetrafluoroethylene fine powders differs from at least one of the other powders in average molecular weight.
Claim 4
Dependent Claim
38 words
A process as claimed in claim 1, wherein at least one of said polytetrafluoroethylene fine powders has an average molecular weight which is larger than that of at least one of the other powders by at least 1,000,000.
Claim 5
Dependent Claim
20 words
A process as claimed in claim 1, wherein at least one of said polytetrafluoroethylene fine powders contains a non-fiber-forming material.
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) | 1994-11-11 | 1995-05-13 | 1995-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-11-11 | 1999-05-13 | 1999-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-11-11 | 2003-05-13 | 2003-11-12 | $7700.00 | Window Closed / Lapsed |