Appeal No. 2001-0172
Application 08/932,771
compositions, even though the reference teaches that the polymers and interpolymers produced
by CG catalyst compositions can be blended with synthetic and natural polymers, including
polyethylene and ethylene/α-olefin copolymers, in order to obtain products with improved
properties. And, second, in that Stevens ‘815 does not teach that the interpolymers formed by the
processes thereof have the melting points, molecular weight distribution and crystallization onset
temperature specified in appealed claims 1 and 21.
With respect to the first difference, we find that appellants acknowledge that it was
known in the art to prepare blends of polymers and interpolymers prepared from ethylene, with
and without comonomers, citing both Ewen and Stehling as examples of such knowledge
(specification, pages 2-3). Indeed, appellants state that “[m]any methods of polymerizing
polymers and forming polymer blends to do specific jobs are disclosed in the literature” (id., page
2, lines 22-24; emphasis supplied). According to appellants, Ewen “teaches the use of a
homogeneous catalyst system comprising at least two different mono-, di- or tri-
cyclopentadienyls and their derivatives of a Group 4b, 5b and 6b transition metal each having
different reactivity ratios and aluminoxane” (id., lines 24-29), while in Stehling “[t]he
components are said to be prepared using metallocene catalyst systems known to provide narrow
composition distributions and narrow molecular weight distributions,” wherein “[t]he desirable
molecular weight and composition distributions are said to be obtained by blending different
components or by polymerization of the blend components in the same or multiple reactors” (id.,
page 3, lines 10-16).
We agree with appellants’ characterization of Stehling and Ewen. We find that Stehling
states that “[t]he blends of the present invention are prepared by blending the desired components
in the desired proportions using conventional blending, techniques and apparatus . . .
Alternatively, the blends may be made by direct polymerization, without isolation of the blend
components, using, for example, two or more catalysts in one reactor, or by using a single
catalyst and two or more reactors in series or parallel” (page 18). We further find that the
cyclopentadienyl containing metallocene catalyst compositions used by Stehling differ from the
cyclopentadienyl containing CG catalyst compositions of Stevens ‘815 in that these single-site
catalysts are bonded differently to the metal component, and polymerize different polymers and
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