| abstract |
To provide a filter medium for an air filter, a filter bag, an air filter unit, and a method for manufacturing such a filter medium for an air filter, which not only have high collection efficiency and low pressure loss, but also have a high dust storage capacity. In the air filter filter material (1) that is arranged with the pre-collector (10), the first porous membrane (31) and the second porous membrane (32) in order from the upstream side, for the first porous membrane (31) and the second porous membrane (32), the pressure loss when making air flow through at a flow velocity of 5.3cm/second is respectively below 30Pa and below 90Pa; When the flow velocity of cm/second flows through, the trapping efficiency for particles is respectively not less than 95% and not more than 99.9%, and for the pre-collector (10), the pressure loss when making air flow at a flow velocity of 5.3cm/second is more than 5 Pa and Less than 55 Pa, when the air containing NaCl particles with a particle diameter of 0.3 μm flows at a flow rate of 5.3 cm/sec, the particle collection efficiency is 15% or more and less than 85%, and the thickness is greater than 0.4mm. |