Porous polytetrafluoroethylene membrane, method for producing the same, gas-permeable membrane and ventilation member using the same

Patent metadata

Field	Value
Publication number	US-9630150-B2
Application number	US-201314418043-A
Country	US
Kind code	B2
Filing date	Jul 26, 2013
Priority date	Aug 2, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

The present invention provides a porous polytetrafluoroethylene membrane having a surface coated with a liquid-repellent agent. In this porous polytetrafluoroethylene membrane, the liquid-repellent agent is a polymer obtained by polymerization of monomers consisting essentially of CH 2 ═CHCOOCH 2 CH 2 C 6 F 13 . This porous polytetrafluoroethylene membrane is suitable for use as a gas-permeable membrane that allows passage of gases but prevents entry of liquids and/or dust, specifically as a waterproof sound-transmitting membrane, a waterproof gas-permeable membrane, or a dustproof gas-permeable membrane.

First claim

The invention claimed is:

1. A porous polytetrafluoroethylene membrane having a surface coated with a liquid-repellent agent, wherein
the liquid-repellent agent is a polymer obtained by polymerization of a monomer consisting of CH 2 ═CHCOOCH 2 CH 2 C 6 F 13 , and
an elongation of the coated membrane at break is 200 to 600%.

2. The porous polytetrafluoroethylene membrane according to claim 1 , wherein the porous polytetrafluoroethylene membrane is dyed black.

3. The porous polytetrafluoroethylene membrane according to claim 1 , wherein a sound pressure loss at 500 Hz is 0.5 to 2.0 dB.

4. A method for producing the porous polytetrafluoroethylene membrane according to claim 1 , comprising:
a forming step of forming a sheet-shaped body from a mixture containing polytetrafluoroethylene;
a first stretching step of stretching the sheet-shaped body in a first direction to form a porous membrane;
a liquid-repellent treatment step of subjecting the sheet-shaped body stretched in the first direction to liquid-repellent treatment using a liquid-repellent treatment solution containing, as a liquid-repellent agent, a polymer obtained by polymerization of monomers consisting essentially of CH 2 ═CHCOOCH 2 CH 2 C 6 F 13 ; and
a second stretching step of stretching the sheet-shaped body in a second direction different from the first direction to form a porous membrane imparted with liquid repellency.

5. A gas-permeable membrane that allows passage of gases but prevents entry of liquids and/or dust, the gas-permeable membrane having a multilayer structure including the porous polytetrafluoroethylene membrane according to claim 1 and a gas-permeable supporting member, wherein
the porous polytetrafluoroethylene membrane is exposed on at least one principal surface of the gas-permeable membrane.

6. A ventilation member comprising:
the porous polytetrafluoroethylene membrane according to claim 1 ; and
a supporting member supporting the porous polytetrafluoroethylene membrane.

7. A ventilation member comprising:
the gas-permeable membrane according to claim 5 ; and
a supporting member supporting the gas-permeable membrane.

Assignees

• Nitto Denko Corp

Inventors

• Mori Masaaki
• Ikeyama Yoshiki

Classifications

• C08J7/0427

  with only one layer of a composition containing a polymer binder (with more layers C08J7/042) · CPC title

• B32B2255/26

  Polymeric coating · CPC title

• B32B2264/0257

  Polyolefin particles, e.g. polyethylene or polypropylene homopolymers or ethylene-propylene copolymers · CPC title

• B32B27/281

  comprising polyimides · CPC title

• B01D71/36

  Polytetrafluoroethylene · CPC title