Claims
- 1. A polytetrafluoroethylene porous film which is formed from a polytetrafluoroethylene resin molding powder obtained by suspension polymerization, wherein said film has a porosity of 40 to 80%, a water permeability of not less than 200 liter/hr..multidot.m.sup.2 .multidot.atm and a removal ratio of uniform particles having a 0.038 .mu.m diameter of not less than 76%.
- 2. The polytetrafluoroethylene porous film as claimed in claim 1, wherein the porous film has a thickness of 10 to 500 .mu.m and is formed from a united product obtained by laminating two or more polytetrafluoroethylene films one upon another and fusing them.
- 3. The polytetrafluoroethylene porous film as claimed in claim 1, wherein the porosity is 40 to 60%.
- 4. The polytetrafluoroethylene porous film as claimed in claim 1, wherein the water permeability is not less than 300 liter/hr..multidot.m.sup.2 .multidot.atm.
- 5. The polytetrafluoroethylene porous film as claimed in claim 4, wherein the water permeability is not less than 350 liter/hr..multidot.m.sup.2 .multidot.atm.
- 6. The polytetrafluoroethylene porous film as claimed in claim 1, wherein the water permeability is not less than 800 liter/hr..multidot.m.sup.2 .multidot.atm.
- 7. The polytetrafluoroethylene porous film as claimed in claim 1, wherein said film has a removal ratio of uniform particles having a 0.038 .mu.m diameter of not less than 76% and a removal ratio of uniform particles having a 0.069 .mu.m diameter of 100%.
- 8. The polytetrafluoroethylene porous film as claimed in claim 1, wherein the polytetrafluoroethylene constituting said film has a crystallinity of not more than 65%.
- 9. The polytetrafluoroethylene porous film as claimed in claim 1, wherein said film has a bubble point of not less than 3 kg/cm.sup.2.
Priority Claims (3)
Number |
Date |
Country |
Kind |
3-1645631 |
Jul 1991 |
JPX |
|
3-330481 |
Dec 1991 |
JPX |
|
3-330480 |
Dec 1991 |
JPX |
|
Parent Case Info
This application is a continuation-in-part application of U.S. application Ser. No. 07/909,174, filed Jul. 6, 1992, U.S. No. 5,358,678 which in turn is a continuation-in-part application of U.S. application Ser. No. 07/907,849, filed Jul. 2, 1992, now abandoned.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4478665 |
Hubis |
Oct 1984 |
|
4707314 |
Kawahigashi et al. |
Nov 1987 |
|
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
909174 |
Jul 1992 |
|
Parent |
907849 |
Jul 1992 |
|