Appeal No. 1999-2808
Application 08/772,351
chloride thermal degradation (pages 49 and 53).
The examiner relies upon Vijlbrief for a teaching that
zinc stearate, dilauryl thiodipropionate and phenolic
antioxidants were known to be suitable for use in polyvinyl
chloride containers which contact food (col. 2, lines 44-45
and 57; col. 3, lines 1-7), and relies upon Minagawa for an
example (5-2) in which the use of stabilizers increased the
time before yellowing and blackening of polyvinyl chloride
(answer, pages 5 and 8).
The examiner argues that in view of Wypych, it would have
been obvious to one of ordinary skill in the art to use an
epoxy stabilizer instead of a calcium soap to offset a zinc
soap’s deleterious effects (answer, page 8). Wypych, however,
does not disclose the relative effect of epoxy stabilizers
versus that of calcium soaps. Thus, he does not indicate that
epoxy stabilizers are suitable substitutes for calcium soaps
for offsetting the negative effects of zinc soaps used
stabilize polyvinyl chloride.
Moreover, Rhodes teaches that calcium salts or epoxidized
soya oils, when used in combination with zinc-containing
stabilizers, will not prevent sudden degradation of polyvinyl
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