Appeal No. 95-3976
Application 08/164,733
15-20 which are all of the claims remaining in the application. Claim 15, the sole independent claim on
appeal, was amended by an amendment after final which was approved for entry by the examiner (paper
nos. 15 and 16). We affirm.
Claimed Subject Matter
The claims on appeal are directed to a process for improving the viscosity index of a base oil by
forming a star polymer and then blending the polymer with a base oil. On page 3 of the brief, appellants
acknowledge all of the pending claims stand or fall together. Accordingly, we will limit our consideration
to claim 15 which reads as follows:
15. A process for improving the viscosity index (VI) of a base oil, comprising the
steps of:
sequentially polymerizing styrene, isoprene, and a polyalkenyl coupling agent to
form a star polymer having the formula (A-B) -X wherein B is a hydrogenated block of
n
polyisoprene having a number average molecular weight (MW ) between 30,000 and
1
60,000, A is a block of polystyrene having a number average molecular weight (MW )
s
from 3,000 to 4,000, X is a nucleus of the polymerized polyalkenyl coupling agent, and n
is the number of block copolymer arms in the star polymer when coupled with 2.5 or more
moles of the polyalkenyl coupling agent per mole of living block copolymer molecules;
recovering the star polymers as a solid crumb; and
blending a VI improving amount of the star polymer crumb with a base oil.
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