Appeal No. 1998-3209
Application 08/338,284
Brown, 459 F.2d 531, 535, 173 USPQ 685, 688 (CCPA 1972), along with the physical properties
which the claimed homo- and copolymers so produced are specified to possess. We interpret the
plain, generic language of the process limitations to permit the use of any process conditions in
the sequential polymerization process as long as two stages are employed along with the
specified catalyst. Through the use of the open-ended term “comprising,” the catalyst is not
limited to the stated catalyst, co-catalyst and silane components or any amounts thereof, but can
contain other ingredients or components, including other polymerization catalysts, co-catalysts,
internal electron donors and external electron donors, bearing in mind that the specified physical
properties must be obtained. See In re Baxter, 656 F.2d 679, 686-87, 210 USPQ 795, 802-03
(CCPA 1981) (“As long as one of the monomers in the reaction is propylene, any other monomer
may be present, because the term ‘comprises’ permits the inclusion of other steps, elements, or
materials.”). With respect to the specified physical properties, the ratio of weight average
molecular weight to number average molecular weight, Mw/Mn, that is molecular weight
distribution, must be greater than 20, and the melt index value, MIL, must be greater than 2g/10
minutes.
We have carefully reviewed the teachings of Cohen and find that the reference would
have disclosed to one of ordinary skill in this art the preparation of a crystalline propylene
homopolymer or copolymer of propylene and another alpha-olefin by sequential polymerization
using a catalyst system under polymerization conditions as taught in the reference (e.g., cols. 5-8
and 10-13, and Example 14). Indeed, Cohen clearly provides for the preparation of highly
crystalline homopolymers and copolymers of propylene which have, inter alia, a molecular
weight distribution of 6 to about 50 and “a useful melt flow rate of at least about 0.1 up to about
200 grams per 10 minutes,” by sequential polymerization in at least two stages, wherein each of
the stages can be conducted in batch in the same reactor and the conditions for polymerization
include “the use of a molecular weight control agent or other techniques to control the molecular
weights of the homopolymer or copolymer produced in each stage,” such as hydrogen (e.g., col.
5, lines 29-55, col. 6, line 27, to col. 8, line 37, and col. 10, line 20, to col. 11, line 3). The
1 The examiner withdrew the grounds of rejection under 35 U.S.C. § 112, second paragraph, and
35 U.S.C. § 102(e) over Cohen (answer, page 3).
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