Appeal No. 2006-2694
Application No. 09/910,968
“precisely the kind of distillation temperature the present Applicants have
taught is to be avoided.” (Br. 6.)
We do not find Appellants’ argument persuasive. Arhancet clearly
teaches that nitroxyl compounds should be used as inhibitors when preparing
styrene monomer, despite any difficulties their use might entail. (Arhancet,
col. 2, ll. 28-52.)
Also, as pointed out by the Examiner (Answer 4-5), the Specification
states that: “It is known in the industry that the recycling of streams utilizing
nitroxyls as polymerization inhibitors in plants employing temperatures in
excess of about 115° C causes loss of inhibitor efficiency, such that the tar
recycle leads to a higher polymer content than would be expected or
desirable.” (Specification 13.)
We agree with the Examiner (Answer 5) that, given the knowledge in
the industry that recycling nitroxyl inhibitors above 115°C causes loss of
inhibitor efficiency, one skilled in the art using Higgins’ recycling step in
Arhancet’s process would have considered it obvious to perform the
recycling step at the claimed temperature of 110°C or less. In our view,
when the prior art discloses that performing a process above a certain
temperature leads to undesirable results, one of ordinary skill would have
considered it obvious to use a lower temperature.
Appellants also point out that Higgins discloses that recycling the
dinitrophenol inhibitor results in an inhibitor which is more effective than
commercial dinitrophenol inhibitors. (Br. 6 (citing Higgins, col. 1, ll. 61-66,
and col. 4, Example 3).) Aware of the industry knowledge that recycling
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