Appeal 2007-1945
Application 10/669,215
chain small amounts of from 0.5 to 5% by weight of dissimilar
units in order to break down any tendency whatever for the
“100%” pure polyester to crystallize. (Col. 3, ll. 28-38.)
Consistent with the above disclosure, Allen discloses an improved
thermoplastic composition comprising a blend of an aromatic polycarbonate
and a polyester derived from a glycol and at least one aromatic dicarboxylic
acid (col. 4, ll. 19-44). The polyester “may be prepared by procedures well
known to those skilled in this art…” using a conventional condensation
catalyst, such as a titanium based catalyst (col. 7, l. 52 to col. 8, l. 7).
Allen does not specifically mention the amount of the catalyst employed in
preparing the polyester.
To remedy this deficiency, the Examiner has relied on the disclosure
of Hillbert. Hillbert focuses on using a particular condensation catalyst
system to improve the property of a polyester (col. 2, ll. 35-39). The novel
catalyst system employed is said to speed up the reaction
so that it is useful for economical purposes and for making a
range of molecular weights useful for molding purposes but
which also results in a condensation polymer having good
clarity and color. Furthermore, environmental concerns
demand that the level of catalyst metals be decreased or
minimized which is achieved by using the process or this
invention (col. 2, ll. 20-26)
Hillbert goes on to teach a polyester (polyethylene terephthalate or modified
polyethylene terephthalate) prepared from a glycol and preferably aromatic
dicarboxylic acid or ester (the same components taught by Allen), in the
presence of a catalyst system comprising from 1 to about 50 parts of
titanium present in the form of an alkyl titanate and from about 1 to about
10
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