CN-116806164-B - Air filter medium, method for producing air filter medium, filter medium for mask, and filter medium for pleated mask

Abstract

The invention provides an air filter medium which has low pressure loss and high performance and is not easy to be blocked, a manufacturing method of the air filter medium, a filter medium for a mask and a filter medium for a pleated mask. An air filter medium (30) comprising a fluororesin porous membrane (31) and a gas-permeable support (32) laminated on the fluororesin porous membrane (31), wherein the fluororesin porous membrane (31) has a pressure loss of 80Pa or less when air is passed through the membrane at a flow rate of 5.3 cm/sec, and the air-permeable support is characterized in that the air-permeable support is formed by a PF value of 20 or more determined by PF value= { -log ((100-capturing efficiency (%))/100) }/(pressure loss (Pa)/1000) and has a thickness of 10 [ mu ] m or more, and the dust retention amount of the poly [ alpha ] -olefin particles is 15.0g/m 2 .3 cm/sec or more when the pressure loss is increased to the extent of 250Pa by using the capturing efficiency of NaCl particles having a particle size of 0.1 [ mu ].

Inventors

• AOMI HIDEKI
• Qian Bangyan
• Pu Gangshenshu
• Shibuya Yoshino

Assignees

• 大金工业株式会社

Dates

Publication Date

20260505

Application Date

20220202

Priority Date

20210204

Claims (6)

1. 1. An air filter medium (30) is provided with: Porous fluororesin membrane (31) A support (32) laminated on at least one side of the fluororesin porous membrane, It is characterized in that the method comprises the steps of, In the fluororesin porous membrane, the pressure loss when air is passed through the membrane at a flow rate of 5.3 cm/sec is 80 Pa or less, The porous fluororesin membrane is characterized in that the PF value determined by the formula of PF value = { -log ((100-capturing efficiency (%))/100) }/(pressure loss (Pa)/1000) is 20 or more by utilizing the pressure loss and the capturing efficiency obtained by using NaCl particles having a particle diameter of 0.1 μm, The fluororesin porous membrane has a thickness of 10 μm or more and 50 μm or less, The fluororesin porous membrane is continuously passed through air containing poly-alpha-olefin particles having a number median particle diameter of 0.25 mu m at a flow rate of 5.3 cm/sec, and the dust holding amount of the poly-alpha-olefin particles is 15.0 g/m 2 or more when the pressure loss increases to the extent of 250 Pa, The air filter medium is manufactured by a method for manufacturing an air filter medium, comprising the steps of: Preparing a fluororesin sheet by using a fluororesin raw material; extending the fluororesin sheet in the 1 st direction at an extension speed in the extension direction of 30%/sec or less, and After the step of extending in the 1 st direction, extending in a2 nd direction orthogonal to the 1 st direction, The total extension ratio is 250-800 times.
2. 2. An air filter media as in claim 1, wherein, The coefficient of variation of the pressure loss is 6.0 or less.
3. 3. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane comprises a fibrillatable polytetrafluoroethylene, a non-heat-fusible component that does not fibrillate, and a heat-fusible component that does not fibrillate and has a melting point of less than 320 ℃.
4. 4. An air filter medium according to claim 1 or2, wherein, The fluororesin porous membrane contains a modified polytetrafluoroethylene.
5. 5. A filter medium for a mask, comprising the air filter medium according to any one of claims 1 to 4.
6. 6. A filter medium (20) for a pleated mask, wherein the air filter medium according to any of claims 1 to 4 is formed in a shape including mountain and valley folds, The pressure loss of the pleated filter for mask in this state when the filter was passed through air at a flow rate of 40L/min was 120 Pa or less by continuously passing air containing poly-alpha-olefin particles having a number median particle diameter of 0.25 [ mu ] m at a flow rate of 85L/min and supporting poly-alpha-olefin particles of 200 mg.

Description

Air filter medium, method for producing air filter medium, filter medium for mask, and filter medium for pleated mask Technical Field The invention relates to an air filter medium, a method for manufacturing the air filter medium, a filter medium for mask and a filter medium for pleated mask. Background Conventionally, as an air filter, for example, a porous membrane (hereinafter, sometimes referred to as PTFE porous membrane) containing polytetrafluoroethylene (hereinafter, sometimes referred to as PTFE) has been used. The PTFE porous membrane is particularly suitable for use in HEPA filters (HIGH EFFICIENCY Particulate AIR FILTER, high-efficiency air Particulate filters) or ULPA filters (Ultra low Penetration AIR FILTER, ultra low permeability air filters) in terms of higher dust capturing efficiency when compared with glass fiber filters at the same pressure loss. As such a filter, for example, an air filter medium having a PTFE porous membrane with good performance has been proposed as described in patent document 1 (international publication No. 2013/157647). Disclosure of Invention Technical problem to be solved by the invention However, as an air filter medium having a fluororesin porous membrane, it is required to have a low pressure loss and high performance, and to prevent clogging. Technical proposal adopted for solving the technical problems The air filter medium according to the 1 st aspect is an air filter medium comprising a fluororesin porous membrane and a support material laminated on the fluororesin porous membrane. The fluororesin porous membrane has a pressure loss of 80Pa or less when air is passed through the membrane at a flow rate of 5.3 cm/sec. The PF (power factor) value of the fluororesin porous membrane is 20 or more. The PF value was determined by the following formula, that is, PF value = { -log ((100-capturing efficiency (%))/100) }/(pressure loss (Pa)/1000), using the pressure loss and the capturing efficiency grasped by using NaCl particles having a particle diameter of 0.1. Mu.m. The thickness of the fluororesin porous membrane is 10 μm or more. The dust-holding amount of the fluororesin porous membrane is 15.0g/m 2 or more. The dust retention amount means the dust retention amount of the poly-alpha-olefin particles when the pressure loss at the porous fluororesin membrane increases by about 250Pa by continuously passing air containing the poly-alpha-olefin particles having a number median particle diameter of 0.25 μm through the porous fluororesin membrane at a flow rate of 5.3 cm/sec. The pressure loss, PF value, and dust holding amount of the porous fluororesin membrane may be all values in the uncharged state of the porous fluororesin membrane. The uncharged air filter medium is one that has been uncharged by the neutralization treatment according to "test method for neutralization treatment of a ventilation air filter unit" section 4 of JIS B9908-4. Further, the fluororesin porous membrane can maintain the capturing efficiency while suppressing the decrease in the capturing efficiency even when the porous membrane is changed from the charged state to the uncharged state, as compared with an electret filter or the like. The air filter medium has a pressure loss of 80Pa or less due to the fluororesin porous membrane, and the pressure loss is suppressed to be low. The air filter medium has a high performance because the PF value of the fluororesin porous membrane is 20 or more. Further, the air filter medium is less likely to be clogged because the dust retention amount of the fluororesin porous membrane is 15.0g/m 2 or more. The air filter medium of item 2 is the air filter medium of item 1, wherein the fluororesin porous membrane has a thickness of 50 μm or less. The air filter medium can suppress the thickness to be small. The air filter medium according to the 3 rd aspect is the air filter medium according to the 1 st or 2 nd aspect, wherein a coefficient of variation in pressure loss of the air filter medium is 6.0 or less. The coefficient of variation of the pressure loss is a value obtained by dividing the standard deviation of the pressure loss distribution by the average value. With respect to the fluororesin porous membrane in which the pressure loss is suppressed to be small, the pressure loss is liable to vary from one part of the membrane to another. However, in this air filter medium, the uniformity can be improved by suppressing the coefficient of variation in the pressure loss to be small. The air filter medium according to the 4 th aspect is the air filter medium according to any one of the 1 st to 3 rd aspects, wherein the fluororesin porous membrane comprises a fibrillatable polytetrafluoroethylene, a non-melt processable component that does not fibrillate, and a non-melt processable component that does not fibrillate with a melting point of less than 320 ℃. In this air filter medium, the porous fluororesin membrane can be increased in the number of vo