Search

CN-112770827-B - Air filter medium, filter pack, air filter unit, and method for producing these

CN112770827BCN 112770827 BCN112770827 BCN 112770827BCN-112770827-B

Abstract

An air filter medium, a filter bag, an air filter unit, and a method for manufacturing the same, each having a low filling ratio and a low thickness. The air filter medium comprises a fluororesin porous membrane having a portion with a filling rate of 3.5% or less and a thickness of 45 [ mu ] m or more in the portion with the filling rate of 3.5% or less.

Inventors

  • Tani Yoshino
  • Qian Bangyan
  • YAMAMOTO SEIGO
  • AOMI HIDEKI
  • KANDA MASAHIRO

Assignees

  • 大金工业株式会社

Dates

Publication Date
20260505
Application Date
20190925
Priority Date
20180928

Claims (17)

  1. 1. An air filter material is characterized in that, The air filter medium comprises a fluororesin porous membrane having a portion with a filling ratio of 3.5% or less, The thickness of the portion having a filling ratio of 3.5% or less is 45 μm or more, The air filter medium is obtained by a method for producing an air filter medium comprising the steps of: preparing an unfired film comprising polytetrafluoroethylene, and Extending the unfired film in a first direction and then in a second direction orthogonal to the first direction to obtain a porous film, Heating the unfired film for more than one minute in a temperature environment of 250 ℃ to 325 ℃ before extending the unfired film in the first direction, Or the air filter medium is obtained by a method for producing an air filter medium comprising the steps of: preparing an unfired film comprising polytetrafluoroethylene; Extending the unfired film, and The unfired film after the stretching is stretched in such a manner that a portion formed by stretching at a stretching speed of 30%/sec or less in the stretching direction is generated, thereby obtaining a porous film.
  2. 2. An air filter media as in claim 1, wherein, The fluororesin porous membrane has a portion with a filling rate of 2.5% or less, The thickness of the portion having the filling rate of 2.5% or less is 50 μm or more.
  3. 3. An air filter medium according to claim 1 or2, wherein, As for the air filter medium, a pressure loss and a trapping efficiency grasped by using polyalphaolefin particles having a particle diameter of 0.3 μm were used, and the PF value determined by the following formula was 17 or more, and the PF value = { -log ((100-trapping efficiency (%))/100) }/(pressure loss (Pa)/1000).
  4. 4. An air filter medium according to claim 1 or2, wherein, Regarding the air filter medium, air including polyalphaolefin particles having a number of median diameters of 0.25 μm was continuously ventilated at a flow rate of 5.3 cm/sec so that the dust storage amount of the polyalphaolefin particles at the time of a pressure loss rise of 250Pa was 30.0g/m 2 or more.
  5. 5. An air filter medium according to claim 1 or2, wherein, The air filter medium has a pressure loss of 200Pa or less when air passes through the air filter medium at a flow rate of 5.3 cm/sec.
  6. 6. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane has an average pore diameter of 2.5 μm or more.
  7. 7. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane comprises: A first fluororesin porous membrane having a filling rate of 3.5% or less and a thickness of 45 [ mu ] m or more, and And a second fluororesin porous membrane disposed on the downstream side of the gas flow with respect to the first fluororesin porous membrane, wherein the filling rate of the second fluororesin porous membrane is larger than the filling rate of the first fluororesin porous membrane.
  8. 8. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane has at least one inclined-density porous membrane having a density on the downstream side of the gas flow that is greater than a density on the upstream side of the gas flow.
  9. 9. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane is a membrane having a filling rate of 3.5% or less and a thickness of 45 [ mu ] m or more.
  10. 10. An air filter medium according to claim 1 or 2, wherein, The air filter medium further includes a pre-trapping membrane disposed on an upstream side of the air flow with respect to the fluororesin porous membrane, In the pre-capture film, The pressure loss when air passes through the pre-trapping film at a flow rate of 5.3 cm/sec is 15Pa to 55Pa, When air including poly alpha olefin particles having a particle diameter of 0.3 μm is caused to pass through the pre-trapping film at a flow rate of 5.3 cm/sec, the pre-trapping film has a trapping efficiency for the poly alpha olefin particles of 25% or more and less than 80%, Using the pressure loss and trapping efficiency grasped by using the polyalphaolefin particles having a particle diameter of 0.3 μm, the PF value determined by the following formula was 7 to 15, and the PF value = { -log ((100-trapping efficiency (%))/100) }/(pressure loss (Pa)/1000).
  11. 11. An air filter medium according to claim 1 or 2, wherein, At least a portion of the fluororesin porous membrane having a filling ratio of 3.5% or less contains a modified polytetrafluoroethylene.
  12. 12. An air filter medium according to claim 1 or 2, wherein, At least a portion of the fluororesin porous membrane having a filling ratio of 3.5% or less contains polytetrafluoroethylene capable of being fibrillated, a non-heat-fusible component which does not become fibrillated, and a component which does not become fibrillated but can be heat-fusible with a melting point of less than 320 ℃.
  13. 13. An air filter medium according to claim 1 or 2, wherein, The air filter medium further includes a ventilation support layer disposed on the upstream side and/or downstream side of the air flow with respect to the fluororesin porous membrane.
  14. 14. A filter pack, characterized in that, The filter pack comprising the air filter media of claim 1 or 2, The air filter medium is processed into a zigzag shape formed by alternately repeating the outer folds and the inner folds.
  15. 15. An air filter unit, comprising: an air filter medium according to claim 1 or 2, and And a frame for holding the air filter medium.
  16. 16. A method for manufacturing a filter cartridge, comprising the steps of: The air filter medium according to claim 1 or 2 is processed into a zigzag shape by alternately repeating the outer folds and the inner folds.
  17. 17. A method of manufacturing an air filter unit, comprising the steps of: The air filter medium according to claim 1 or 2 or the filter pack obtained by the method for producing a filter pack according to claim 16 is held in a frame.

Description

Air filter medium, filter pack, air filter unit, and method for producing these Technical Field The present disclosure relates to an air conditioner filter medium, a filter pack, an air filter unit, and methods of manufacturing these. Background Conventionally, in order to obtain a sufficiently clean space, a porous membrane (hereinafter referred to as PTFE porous membrane) composed of, for example, polytetrafluoroethylene (hereinafter referred to as PTFE) has been used as a dust collecting filter. Since the porous PTFE membrane has higher dust collection efficiency when compared with a filter material made of glass fibers at the same pressure loss, it is particularly preferable to use a HEPA filter (high efficiency particulate air filter) and an ULPA filter (ultra low permeability air filter). As such a filter, for example, as an air filter medium described in patent document 1 (japanese unexamined patent publication No. 2001-170461), there has been proposed a method in which the dust storage amount is increased by setting the thickness of a PTFE porous membrane to about 10 μm and the filling rate to about 5%. Disclosure of Invention Technical problem to be solved by the invention However, as a fluororesin porous membrane, a fluororesin porous membrane having a low filling rate and a thickness has not been proposed so far. In view of the foregoing, an object of the present disclosure is to provide an air filter medium having a thickness and a low filling rate, a filter bag, an air filter unit, and methods of manufacturing these. Technical proposal for solving the technical problems The air filter medium of the first aspect includes a fluororesin porous membrane. The fluororesin porous membrane has a portion with a filling rate of 3.5% or less. The thickness of the portion of the fluororesin porous membrane having a filling rate of 3.5% or less is 45 μm or more. The fluororesin porous membrane may be constituted by a single porous membrane having a filling rate of not more than 3.5% and not more than 45 μm, by a single porous membrane having a filling rate which does not substantially change in the gas flow direction, by a single porous membrane having a filling rate which changes in the gas flow direction, or by a plurality of porous membranes having a filling rate which does not substantially change in the gas flow direction or which changes in the gas flow direction. The air filter medium can have a thickness and a low filling rate. The air filter medium according to the second aspect has a portion having a filling rate of 2.5% or less in addition to the air filter medium according to the first aspect. The thickness of the portion of the fluororesin porous membrane having a filling rate of 2.5% or less is 50 μm or more. The fluororesin porous membrane may be constituted by a single porous membrane having a filling rate of not more than 2.5% and not more than 50 μm, by a single porous membrane having a filling rate which does not substantially change in the gas flow direction, by a single porous membrane having a filling rate which changes in the gas flow direction, or by a plurality of porous membranes having a filling rate which does not substantially change in the gas flow direction or which changes in the gas flow direction. The air filter medium can be made to have a sufficient thickness and a lower filling rate. The air filter medium according to the first or second aspect is the air filter medium according to the third aspect, wherein the PF value is 17 or more, and the PF value = { -log ((100-capturing efficiency (%))/100) }/(pressure loss (Pa)/1000) is determined by using the pressure loss and capturing efficiency obtained from the polyalphaolefin particles having a particle diameter of 0.3 μm. The air filter medium comprises a fluororesin porous membrane having a low filling rate and a thickness, and can ensure a high PF value. The air filter medium according to the fourth aspect of the present invention is the air filter medium according to any one of the first to third aspects, wherein the dust storage amount of the polyalphaolefin particles is 30.0g/m 2 or more when the pressure loss is increased by 250Pa by continuously ventilating air containing polyalphaolefin particles having a number median diameter of 0.25 μm at a flow rate of 5.3 cm/sec. In addition, the dust storage amount is more preferably 50.0g/m 2 or more. The air filter medium includes a fluororesin porous membrane having a thickness and a low filling rate, and can ensure a high dust storage amount. The air filter medium according to the fifth aspect is the air filter medium according to any one of the first to fourth aspects, wherein the air filter medium has a pressure loss of 200Pa or less when air passes through at a flow rate of 5.3 cm/sec. The air filter medium comprises a fluororesin porous membrane having a low filling rate and a thickness, and can suppress pressure loss to be low. The air filter medium according to any o