Patent US5234739A successfully refreshed from Google Patents.
US5234739A
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US
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Polytetrafluoroethylene porous film and preparation and use thereof
Assignee: Daikin Industries Ltd
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Filing: 1992-07-22
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Granted: 1993-08-10
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Expires: 2012-07-22
Abstract
Abstract A polytetrafluoroethylene porous film, which is prepared by stretching a semisintered polytetrafluoroethylene material and heating the stretched material at a temperature higher than the melting point of sintered polytetrafluoroethylene, has an area ratio of fibrils to nodes of from 99:1 to 75:25, an average fibril diameter of from 0.05 to 0.2 μm, a largest node area of not larger than 2 μm 2 and an average pore size of from 0.2 to 0.5 μm and achieves low pressure loss.
Inventors
- 👤 Shinji Tanaru
- 👤 Osamu Tanaka
- 👤 Hirofumi Nishibayashi
- 👤 Osamu Inoue
- 👤 Katsutoshi Yamamoto
- 👤 Toshio Kusumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:05
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1692; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; B01D69/00; B01D69/10; B01D69/107; B01D69/1071; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29; B29C; B29C55/00; B29C55/005; B01D2323/00; B01D2323/08; B01D2323/081; B01D2325/00; B01D2325/02; B01D2325/0281; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18; Y; Y10; Y10S; Y10S264/00; Y10S264/73; Y10T; Y10T428/00; Y10T428/24; Y10T428/24273; Y10T428/249921; Y10T428/249953; Y10T428/249978; Y10T428/249979; Y10T428/31504; Y10T428/3154; Y10T428/31544
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
89 words
A polytetrafluoroethylene porous film which is prepared by stretching a semisintered polytetrafluoroethylene material and heating the stretched material at a temperature higher than the melting point of sintered polytetrafluoroethylene and has an area ratio of fibrils to nodes of from 99:1 to 75:25, an average fibril diameter of from 0.05 to 0.2 μm and a largest node area of not larger than 2 μm 2 which are determined by an image processing of a scanning electron microscopic photograph, and an average pore size of from 0.2 to 0.5 μm.
Claim 2
Dependent Claim
89 words
A polytetrafluoroethylene porous film which is prepared by stretching a semisintered polytetrafluoroethylene material and heating the stretched material at a temperature higher than the melting point of sintered polytetrafluoroethylene and has an area ratio of fibrils to nodes of from 99:1 to 75:25, an average fibril diameter of from 0.05 to 0.2 μm and a largest node area of not larger than 2 μm 2 which are determined by an image processing of a scanning electron microscopic photograph, and an average pore size of from 0.2 to 0.5 μm.
Claim 3
Dependent Claim
41 words
The polytetrafluoroethylene porous film according to claim 1, at least one of surfaces of which is laminated with a reinforcing material film selected from the group consisting of olefinic porous material films and fluororesin porous films with or without an adhesive.
Claim 4
Dependent Claim
40 words
A polytetrafluoroethylene porous film having an average pore size of from 0.2 to 0.5 μm, and a pressure loss of from 10 to 100 mmH 2 O when an air is passed through at a flow rate of 5.3 cm/sec.
Claim 5
Dependent Claim
40 words
A polytetrafluoroethylene porous film having an average pore size of from 0.2 to 0.5 μm, and a pressure loss of from 10 to 100 mmH 2 O when an air is passed through at a flow rate of 5.3 cm/sec.
Claim 6
Dependent Claim
40 words
A polytetrafluoroethylene porous film which is prepared by biaxially stretching a semisintered polytetrafluoroethylene material at an area draw ratio of at least 50 and heat setting the stretched film at a temperature higher than a melting point of sintered polytetrafluoroethylene.
Claim 7
Dependent Claim
40 words
A polytetrafluoroethylene porous film which is prepared by biaxially stretching a semisintered polytetrafluoroethylene material at an area draw ratio of at least 50 and heat setting the stretched film at a temperature higher than a melting point of sintered polytetrafluoroethylene.
Claim 8
Dependent Claim
41 words
The polytetrafluoroethylene porous film according to claim 4, at least one of surfaces of which is laminated with a reinforcing material film selected from the group consisting of olefinic porous material films and fluororesin porous films with or without an adhesive.
Claim 9
Dependent Claim
46 words
A process for preparing a polytetrafluoroethylene porous film according to claim 1, comprising the steps of biaxially stretching a semisintered polytetrafluoroethylene at an area draw ratio of at least 50 and heat setting the stretched film at a temperature higher than a melting point of polytetrafluoroethylene.
Claim 10
Dependent Claim
28 words
The process according to claim 6, wherein the prepared porous film has a thickness of not larger than about one twentieth of that of the semisintered polytetrafluoroethylene material.
Claim 11
Dependent Claim
12 words
An air filter comprising a polytetrafluoroethylene porous film according to claim 1.
Claim 12
Dependent Claim
12 words
An air filter comprising a polytetrafluoroethylene porous film according to claim 4.
Claim 13
Dependent Claim
34 words
The polytetrafluoroethylene porous film according to claim 2, wherein the reinforcing material film is selected from a film of the group consisting of polyolefin, polyamide, polyester, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene/hexafluoropropylene copolymer and polytetrafluoroethylene.
Claim 14
Dependent Claim
17 words
The polytetrafluoroethylene porous film according to claim 4, wherein the area draw ratio is at least 100.
Claim 15
Dependent Claim
17 words
The polytetrafluoroethylene porous film according to claim 4, wherein the area draw ratio is at least 250.
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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) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |