Appeal No. 2002-0224
Application 08/628,327
the broadest independent claim, i.e., claim 23. Our discussion
of this claim applies equally well to the appellants’ only other
independent claim (27).
Matsuura discloses an electret filter comprising
polypropylene fibers and 0.3 part by weight of a fluorine-
modified silicone oil (page 8, lines 37-52). Matsuura teaches
that the resins which are suitable for use as his electret filter
fibers must have an angle of contact with water of at least
95 degrees, and that the silicone oil renders polypropylene
suitable for use as a material of the electret filter fibers by
sufficiently increasing the angle of contact of the polypropylene
with water (page 2, lines 46-47; page 2, line 56 - page 3,
line 2).
Maruscak discloses a filter medium which may comprise a
microfibrous glass fiber layer upstream from a microfibrous
electret and which may be given a fluorochemical treatment to
render it both hydrophobic and oleophobic so that it resists
plugging and clogging by water and oil aerosols (col. 4,
lines 35-47).
The examiner argues that the appellants apparently are
correct that Maruscak’s exemplary fluorochemical treatment is
applied to the surface of glass fibers (answer, page 9). The
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