Appeal No. 2005-2510 Page 4
Application No. 10/122,049
Smith (column 3, lines 56-60) teaches that trialkyl
phosphates are a preferred class of phosphates for use in forming
the base stock and that the phosphate ester should preferably
comprise from 65 to 99.999 weight percent of the fluid
composition. As pointed out by the examiner (answer, page 3),
Smith discloses that “. . . the erosion effects of phosphate
ester based hydraulic fluids can be greatly diminished if a small
amount of a perfluorinated anionic surfactant is incorporated
into such fluid formulations.” See column 2, lines 46-50 of
Smith. Smith (column 3, lines 4-7) discloses using from 0.001 to
5.0 parts surfactant per 100 parts of the phosphate ester. Smith
provides that the perfluorinated anionic surfactant used is an
alkali metal salt of a perfluoroalkyl sulfonic acid having a
specified formula and provides examples of suitable compounds,
including a sodium perfluorobutane sulfonate, as well as teaching
that potassium may also be employed as the alkali metal in
forming the salts. See column 3, lines 11-26 of Smith. Also,
Smith (column 8, line 47 through column 9, line 8) teaches that
epoxide scavengers, such as claimed, can be included in the fluid
composition base stock. Moreover, Smith discloses that a
viscosity index improver, such as a poly(alkylacrylate) or a
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