Appeal No. 2004-2219 Page 6
Application No. 09/927,009
if the polyester and the diisocyanate are reacted in an NCO:OH ratio of 0.7:1.0 to
1:0.7, a high molecular weight prepolymer which is stirrable above 120 °C and
sufficiently stable prior to the addition of second stage polyols in the reaction can
be formed. By contrast, if a lower molecular weight hydroxyl terminated
polyester is used, i.e., one with a molecular weight of 3600, such as DYNACOLL
7360, in a similar NCO:OH ratio, the viscosity of the resulting prepolymer is too
high for efficient mixing because of the higher concentration of urethane groups.
(emphasis added).
The point being made by Graham is that a different NCO:OH ratio is required when a
hexane diol/adipatic acid polyester (polyester polyol) of a molecular weight such as 3600 is used.
Graham does not state that polyester polyols with molecular weights such as 3600 are inoperable.
Nor can we agree that Graham does not enable the use of, or that the reference teaches away
from, polyester polyols having the lower molecular weights in the disclosed range of 2,000-
15,000 range. We agree with the Examiner that Graham discloses using polyester polyols of
molecular weights overlapping the claimed range. We further point out that even if Graham did
teach away from using polyols of molecular weights of 3600 and below, there would still be an
overlap with the claimed range at 3,601-5,000.
Here, Graham is teaching the formation of hot melt adhesives as claimed using process
steps as claimed and with ingredients which overlap in type and concentration. The Examiner
has established a prima facie case of obviousness based upon the overlapping ranges and the
burden has shifted to the Appellant to show that the particular range is critical. See Woodruff,
919 F.2d at 1578, 16 USPQ2d at 1936-37. Appellant presents no evidence of criticality in this
appeal.
We conclude that the Examiner has established a prima facie case of obviousness with
respect to the subject matter of claims 1-3 which has not been sufficiently rebutted by Appellant.
Page: Previous 1 2 3 4 5 6 7 8 9 Next
Last modified: November 3, 2007