EP0525630A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Polytetrafluoroethylene porous film and preparation and use thereof
Assignee: Daikin Industries Ltd
•
Filing: 1992-07-23
•
Granted: —
•
Expires: 2012-07-23
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 C/O Yodogawa Works Tamaru
- 👤 Osamu C/O Yodogawa Works Tanaka
- 👤 Hirofumi C/O Yodogawa Works Nishibayashi
- 👤 Osamu C/O Yodogawa Works Inoue
- 👤 Katsutoshi C/O Yodogawa Works Yamamoto
- 👤 Toshio C/O Yodogawa Works Kusumi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 05:17
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: 12
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 /1 .m and a largest node area of not larger than 2 u.m2 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 /1 .m and a largest node area of not larger than 2 u.m2 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
The 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 0 when an air is passed through at a flow rate of 5.3 cm/sec.
Claim 5
Dependent Claim
40 words
The 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 0 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.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.