Appeal No. 96-2768
Application 08/118,377
the art would have been led to combine a minor amount of an alkylated aminophenol and a minor amount
zinc dithiophosphate in a lubricating oil with the reasonable expectation that the oil will have detergent,
antioxidant and antiwear properties. Accordingly, we find that the examiner has established a prima facie
case of obviousness over the combined teachings of Lange and Schroeck. Having established a prima
facie case, the burden shifts to appellant to rebut it.
Appellant urges that “neither Lange nor Schroeck nor their combination, teach that alkylated
aminophenols would enhance the valve train wear inhibition performance of primary alcohol-derived zinc
dithiophosphates so that we can take advantage of their thermal stability.” According to appellant, primary
alcohol-derived zinc dithiophosphates are more thermally stable than secondary alcohol-derived
dithiophosphates, but that the primary alcohol-derived zinc dithiophosphates have the disadvantage of not
being as effective in valve train wear inhibition as the secondary alcohol-derived zinc dithiophosphates.
Appellant has discovered that combining an alkylated aminophenol wherein the alkyl group has 18-30
carbon atoms with a zinc dithiophosphate wherein more than 50 mole %, but less than 100 mole %, of the
alkyl groups of the zinc dithiophosphate are derived from primary alcohols enhances the ashless wear
inhibition performance of the zinc dithiophosphate. Appellant points us to the data in Tables I, II and III
on pages 16-18 of the specification as showing unexpected improved performance when the claimed
alkylated aminophenol and zinc dithio-phosphate are combined. We have considered this data, but we
agree with the examiner that it does not rebut the prima facie case.
While the data in Table I shows that a lubricant containing 0.08% of a primary alkyl zinc
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