US5217666A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing porous polytetrafluoroethylene film
Assignee: Daikin Industries Ltd
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Filing: 1992-05-28
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Granted: 1993-06-08
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Expires: 2012-05-28
Abstract
Abstract A porous PTFE film having a thin thickness and good permeability is produced by coating an emulsion of polytetrafluoroethylene on a substrate surface, in particular, a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.
Inventors
- 👤 Shinji Tamaru
- 👤 Hirofumi Nishibayashi
- 👤 Katsutoshi Yamamoto
- 👤 Osamu Tanaka
- 👤 Osamu Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:21
CPC Classifications
B; B29; B29D; B29D7/00; B29D7/01; B01; B01D; B01D67/00; B01D67/0002; B01D67/0004; B01D67/0023; B01D67/0025; B01D67/0027; B01D69/00; B01D69/08; B01D69/12; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29C; B29C41/00; B29C41/003; B29C55/00; B29C55/005; C; C08; C08J; C08J5/00; C08J5/18; B01D2325/00; B01D2325/02; B01D2325/022; B01D2325/04; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
57 words
A process for producing a porous polytetrafluoroethylene film comprising coating an emulsion of polytetrafluoroethylene on a substrate surface, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.
Claim 2
Dependent Claim
57 words
A process for producing a porous polytetrafluoroethylene film comprising coating an emulsion of polytetrafluoroethylene on a substrate surface, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.
Claim 3
Dependent Claim
13 words
The process according to claim 1, wherein said substrate has a smooth surface.
Claim 4
Dependent Claim
19 words
The process according to claim 1, wherein said semi-sintered polytetrafluoroethylene film is peeled off from the substrate and stretched.
Claim 5
Dependent Claim
14 words
The process according to claim 1, wherein said semi-sintered, polytetrafluoroethylene film is biaxially stretched.
Claim 6
Dependent Claim
82 words
A process for producing a multi-layer porous polytetrafluoroethylene film comprising at least two layers having different average pore sizes, which process comprises coating an emulsion of polytetrafluoroethylene on a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating a coated polytetrafluoroethylene substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sintered polytetrafluoroethylene, and stretching a composite of the coated film and the substrate at least in one direction.
Claim 7
Dependent Claim
82 words
A process for producing a multi-layer porous polytetrafluoroethylene film comprising at least two layers having different average pore sizes, which process comprises coating an emulsion of polytetrafluoroethylene on a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating a coated polytetrafluoroethylene substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sintered polytetrafluoroethylene, and stretching a composite of the coated film and the substrate at least in one direction.
Claim 8
Dependent Claim
28 words
The process according to claim 5, wherein said polytetrafluoroethylene substrate has a thickness of 10 to 100 μm and an average pore size of 0.3 to 0.9 μm.
Claim 9
Dependent Claim
17 words
The process according to claim 5, wherein said polytetrafluoroethylene substrate is in the form of a film.
Claim 10
Dependent Claim
18 words
The process according to claim 5, wherein said polytetrafluoroethylene substrate is in the form of a hollow fiber.
Claim 11
Dependent Claim
22 words
The process according to claim 3, wherein said film is uniaxially stretched at a draw ratio of from 1.1 to 3.0 times.
Claim 12
Dependent Claim
39 words
The process according to claim 4, wherein said film is biaxially stretched at a draw ratio in a first direction at most about 2 times, and in another direction perpendicular to the first direction at most about 2 times.
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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) | 1996-06-07 | 1996-12-07 | 1997-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-07 | 2000-12-07 | 2001-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-07 | 2004-12-07 | 2005-06-08 | $7700.00 | Window Closed / Lapsed |