Air filter medium, filter pleat pack, and air filter unit

Patent metadata

Field	Value
Publication number	US-11338233-B2
Application number	US-201816648468-A
Country	US
Kind code	B2
Filing date	Sep 21, 2018
Priority date	Sep 22, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

The air filter medium of the present invention is an air filter medium including a stack of a porous polytetrafluoroethylene (PTFE) membrane and an air-permeable support member, a repulsive force generated in the medium when the medium is compressed in a thickness direction thereof is equal to or greater than 30 kPa and equal to or less than 150 kPa at a compression ratio of 30%, and at least one main surface of the air filter medium is formed by the air-permeable support member and has a maximum coefficient of friction of 24 gf or less. The air filter medium of the present invention is an air filter medium that uses a porous PTFE membrane and in which a decrease in collection efficiency due to pleating is inhibited.

First claim

The invention claimed is:

1. An air filter medium, comprising:
a stack of a porous polytetrafluoroethylene (PTFE) membrane and an air-permeable support member, wherein
a repulsive force generated in the air filter medium when the air filter medium is compressed in a thickness direction thereof is equal to or greater than 30 kPa and equal to or less than 150 kPa at a compression ratio of 30%, and
at least one main surface of the air filter medium is formed by the air-permeable support member and has a maximum friction force of 24 gf or less; and
wherein
the compression ratio of 30% is measured by:
stacking pieces of the air filter medium to provide stacked medium pieces having a total thickness,
compressing, with a compression element, the stacked medium pieces by a distance of 30% of the total thickness in the thickness direction,
wherein a reference position from which compression of the stacked medium pieces starts is defined by a position of the compression element at a time when a load of 0.1 N is applied to an uppermost surface of the stacked medium pieces, the load of 0.1 N excluding the mass of the compression element.

2. The air filter medium according to claim 1 , wherein
the air filter medium has a PF value of 23 or greater, and
the PF value is a value obtained by the following equation (1) from a pressure loss PL (mmH 2 O) of the air filter medium at a permeate flow rate of 5.3 cm/sec and a collection efficiency CE (%) of the air filter medium measured at a permeate flow rate of 5.3 cm/sec using polyalphaolefin particles having a particle diameter of 0.10 to 0.20 μm,
PF value={−log [(100−CE)/100]/PL}×100  (1).

3. The air filter medium according to claim 2 , wherein the PF value is equal to or greater than 30.

4. The air filter medium according to claim 1 , wherein the air filter medium has a surface density equal to or greater than 55 g/m 2 and equal to or less than 95 g/m 2 .

5. The air filter medium according to claim 1 , wherein the air filter medium has a surface density equal to or greater than 55 g/m 2 and equal to or less than 75 g/m 2 .

6. The air filter medium according to claim 1 , wherein
the stack includes two or more air-permeable support members, and
both main surfaces of the air filter medium are formed by the air-permeable support members.

7. A filter pleat pack comprising an air filter medium folded in a pleated manner, wherein
the pleated air filter medium is the air filter medium according to claim 1 .

8. An air filter unit comprising the filter pleat pack according to claim 7 and a frame supporting the filter pleat pack.

Assignees

• Nitto Denko Corp

Inventors

• Horie Yuri
• Mori Masaaki
• Arimitsu Yukio

Classifications

• B01D39/083 Primary

  of organic material · CPC title

• B01D39/16

  of organic material, e.g. synthetic fibres · CPC title

• B01D2239/1291

  Other parameters · CPC title

• B01D71/36

  Polytetrafluoroethylene · CPC title

• B01D63/14

  Pleat-type membrane modules · CPC title