THE INVENTION
The invention is directed to a method of making a low structure pyrogenic metal
oxide filler selected from the group consisting of zirconium oxide, silicon dioxide,
aluminum oxide, and titanium oxide, wherein the particle size is reduced and the bulk
density is increased simultaneously by dry milling using an energy specific force
created by a substantial number of conditions set forth in the claimed subject matter.
The dry milling continues until a steady state is reached and a lowering of the
structure occurs.
Structure is a property defined by the size and shape, the number of particles
per aggregate and their average mass. These characteristics affect aggregate
1
packing and the volume of voids in the bulk material. Structure is measured by DBP
Absorption. Dibutyl phthalate(DBP) is added until the consistency suddenly changes.
See Reply Brief, page 3. As the structure of a pyrogenic metal oxide is lowered, the
oil absorption is reduced.
THE CLAIMS
Claim 1 is illustrative of appellants’ invention and is reproduced below.
1. A method of producing a low structure pyrogenic metal oxide filler
comprising simultaneously reducing particle size/aggregate size and increasing bulk
density by subjecting pyrogenically produced metal oxide agglomerates and
aggregates selected from the group consisting of zirconium oxide, silicon dioxide,
aluminum oxide, and titanium oxide to a dry milling process whereby the pyrogenically
produced metal oxide is
contacted in a agitating zone with an energy specific force created by the following
.1
2
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Last modified: November 3, 2007