Appeal No. 94-2078
Application 07/834,755
polymerization” and “simply varying the order of addition of materials to a reactor lies well within
the skill of the art and is not ordinarily patentable” (page 3, emphasis ours).
We observe that the processes of appealed claim 12 before us and appealed claim 1 in the
‘203 application differ in that appealed claim 12 clearly specifies that the mercaptan chain transfer
agent is “admixed” with “an encapsulating amount” of a vinyl ester of fatty acids and the
“encapsulated mixture” so formed is then added to the suspension polymerization medium while
appealed claim 1 of the grandparent application merely specified that at least 0.03 part by weight
of the “mercaptan is added in the form of a mixture with vinyl ester to the polymerization
medium” (emphasis added) without limitation as to the content or nature of the “mixture” which
can be used for either suspension or emulsion polymerization (specification, page 4, lines 7-13).
We have carefully considered the teachings of Kuwata identified by the prior panel with
respect to the invention as claimed before us and find that we agree with appellant that there is no
direction in this reference which would have led one of ordinary skill in this art to “encapsulate,”
as that term is employed by appellant in appealed claim 12, the mercaptan transfer agents in a
vinyl ester of fatty acids, wherein the acid has at least 4 carbon atoms, prior to incorporating such
an admixture with other components of the aqueous suspension polymerization medium prior to
the start of polymerization. In the teachings of Kuwata identified by the prior panel, the entire
amount of the mercaptan to be employed is added to the suspension polymerization medium,
which contains vinyl chloride as the sole monomer, prior to the start of polymerization. In
Kuwata Example 33 (Table V), the mercaptan is added alone to the polymerization mixture while
in Kuwata Examples 36 (Table VI) and 39 (Table VII), the mercaptan is added together with all
of the other ingredients. We observe that these reference examples are “controls” and thus are
intended to contrast the “delayed addition” of the mercaptan chain transfer agents taught in the
reference to be the solution to the problem of the formation of coarse particles in suspension
polymerization (col. 3, line 47, to col. 4, line 49). As pointed out by appellant in his reply brief
(pages 3-4), in the disclosed “delayed addition” of the mercaptan chain transfer agents according
to the invention set forth in Kuwata, the mercaptan is always added alone to the
polymerization medium regardless of the stage of the polymerization reaction at which all or a
portion of the mercaptan is added. Furthermore, on the record before us, the disclosure of “vinyl
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