Appeal No. 2001-0172
Application 08/932,771
interpolymers from ethylene and the same and similar comonomers (Stehling, e.g., pages 5-6 and
12-17; Stevens ‘815, e.g., page 5, lines 46-51).
We find that Ewen acknowledges that it was known in the art to “produce polymer blends
by polymerizing two or more polymerizable materials in two or more reactors arranged in series”
to produce a blend (col. 2, lines 3-10) and states that “[i]t is highly desirable to be able to readily
and simply produce blends in a single reactor during which polyethylene and copolyethylene-
alpha olefins are produced simultaneously . . . [to obtain] a uniform blending of the polymers and
one can simply ‘tailor’ the polymers with respect to molecular weights, weight fraction and the
like to obtain blends evidencing outstanding properties” (col. 2, lines 11-19). Ewen thus teaches
that “[t]he reactor blends are obtained directly during a single polymerization process, i.e., the
blends of this invention are obtained in a single reactor by simultaneously polymerizing ethylene
and copolymerizing ethylene with an alpha-olefin . . . [which] can be employed in conjunction
with other prior art blending techniques, for example the reactor blends produced in a first
reactor can be subjected to further blending in a second stage by use of the series reactors” (col.
2, lines 30-44). Ewen further teaches that the “catalyst system for the polymerization of reactor
blends . . . [comprises] at least two different metallocenes,” which contain a cyclopentadienyl
moiety, and an activating cocatalyst (col. 2, line 45, to col. 3, line 5), and teaches that the “ratios
of one metallocene to the second metallocene will be a function of both the chemical
composition of the metallocenes as well as the blend being tailored., [sic] accordingly, the ratio
of the two metallocene can vary greatly and, hence, is limited only for the purpose of producing
the blends” (col. 3, lines 6-11). The “ratios” of the metallocenes are thus “reactivity ratios” and
the “tailored blend” results from the reactivity ratio of the catalyst compositions employed (col.
5, line 11, to col. 6, line 20). The metallocene catalyst compositions of Ewen differ from the
cyclopentadienyl containing CG catalyst compositions of Stevens ‘815 in the same manner as the
cyclopentadienyl containing metallocene catalyst compositions used by Stehling, and polymerize
different polymers and interpolymers from the same ethylene and alpha-olefin monomers (col. 3,
lines 19-32).
Based on this substantial evidence, we find that, prima facie, one of ordinary skill in this
art armed with the knowledge in the art that blends of ethylene based polymers and interpolymers
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