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 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.
2 ) An air filter medium according to claim 1 wherein said air filter medium as described in claim 1 in the no-binder condition has the PF value of 9.9 or greater when the PF value is expressed by the following equation (1):
[
Math
1
]
PF
Value
=
log
10
(
1
-
efficiency
[
%
]
/
100
)
pressure
drop
[
Pa
]
/
9.81
×
(
-
100
)
(
1
)
where the efficiency targets the particle diameter in the rage of 0.1-0.15 μm and the face velocity is 5.3 cm/sec.
3 ) An air filter medium according to claim 1 wherein said short glass fibers as described in claim 1 are low boron short glass fibers, and said air filter medium in the no-binder condition has the PF value of 9.0 or greater, when the PF value is expressed by the following equation (1),
[
Math
2
]
PF
Value
=
log
10
(
1
-
efficiency
[
%
]
/
100
)
pressure
drop
[
Pa
]
/
9.81
×
(
-
100
)
(
1
)
where the efficiency targets the particle diameter in the rage of 0.1-0.15 μm and the face velocity is 5.3 cm/sec.