Appeal 2007-2359
Application 90/006,951
DECISION ON APPEAL
A. Introduction
The patent owner ("Alcan") appeals under 35 U.S.C. § 134 from the
final rejection under 35 U.S.C. § 103 of claims 1–5 and 7–20, which are all
of the pending claims in this reexamination of U.S. Patent 6,440,359. We
have jurisdiction under 35 U.S.C. § 6(b). We REVERSE.
The subject matter on appeal relates to aluminum-magnesium-silicon
("AlMgSi") alloys said to be particularly suitable for "the bottom end" of the
extrusion market because they are strong (i.e., have an Aluminum
Association alloy AA6063-T5 or -T6 rating) and can be extruded at a
relatively high rate. (359 patent at 1:11–14.) (AA6063 alloys are said to
account for 80% of all extruded aluminum goods. (Id. at 1:9–10.)) The
inventors state that the industry has obtained such alloys by reducing the
content of Mg2Si while increasing the amount of "excess silicon" and adding
copper ("Cu"), and manganese ("Mn") to obtain extrudability, tensile
strength, and other desired properties. (359 patent at 1:15–25.) However,
according to the inventors, there has been a bias against reducing the content
of Mg to less than 0.35 wt% in general purpose AlMgSi extrusion alloys.
(359 patent at 1:26-31.) The claimed compositions have an Mg content of at
most 0.34 wt%.
Claim 1 is representative of the issues necessary to resolve this appeal
and reads:
A DC cast extrusion ingot of an alloy of composition consisting
of
0.20–0.34 wt.% Mg,
2
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