Appeal No. 1997-0140
Application No. 08/266,290
a one-component polyurethane composition that is useful as a
sealant, does not teach the inclusion of appellants' claimed
component b), i.e., polyketimines, polyenamines and
oxazolidines. While Akiyama discloses a polyurethane coating
composition comprising appellants' component b) as a curative,
we concur with appellants that the compositions of Markusch
and Akiyama are not sufficiently similar to support the
conclusion that it would have been prima facie obvious for one
of ordinary skill in the art to incorporate the curatives of
Akiyama in the polyurethane composition of Markusch. For one,
the examiner has not pointed to any teaching in Markusch that
any curative, in general, is an optional component of the
composition. Markusch relies upon the specific reaction of a
liquid blocked polyisocyanate with a solid polyamine internal
salt. Akiyama, on the other hand, does not disclose a
polyurethane composition comprising a solid polyamine internal
salt but, rather, teaches the specific reaction of a
particular blocked urethane prepolymer derived from TMXDI and
the curatives, such as ketimines. In our view, impermissible
hindsight is required to modify the polyurethane composition
of Markusch by including the curative of Akiyama. While the
examiner explains that the requisite motivation stems from
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