Air filter medium
The objective of the present invention is to provide an air filter medium having a lower pressure drop and higher efficiency as compared to an air filter medium currently in use. This objective is achieved by providing an air filter medium characterized by comprising glass short fibers as its main fibers in which the constituent fibers are dispersed uniformly and, when the constituting fibers at a diluted concentration of 0.04% by mass are allowed to stand for 12 hours, the sedimentation volume is 450 cm 3 /g or greater.
1. An air filter medium, bonded with an organic binder in the form of aqueous solution or aqueous emulsion, characterized by comprising low boron short glass fibers having <0.09% by weight of B 2 O 3 as its main fibers in which 5% or more by mass of AR glass chopped fibers is blended, and, the both constituent fibers are dispersed uniformly and, when the constituent fibers at a diluted concentration of 0.04% by mass are allowed to stand for 12 hours, the sedimentation volume is from 450 cm 3 /g to 730 cm 3 /g.
2. An air filter medium according to claim 1 wherein said air filter medium in a no-binder condition has a PF value of 9.0 or greater when the PF value is expressed by the following equation (1):
PF
Value
=
log
1
c
(
1
-
efficiency
[
%
]
/
100
)
pressure
drop
[
Pa
]
/
9.81
×
(
-
100
)
(
1
)
where the efficiency targets a particle diameter in the range of 0.1-0.15 μm and a face velocity is 5.3 cm/sec.