Appeal No. 1997-4104
Application 08/383,238
about 29 kPoise to about 33 kPoise. See the specification at
page 2, third full paragraph. Appellants’ invention is said
to be based on the finding that when one polymerizes
vinylidene fluoride such that the resulting PVDF polymer has a
melt viscosity of at least 40 kPoise, and formulates a paint
including
such polymer, “such paint has a reduced gloss while being easy
to apply and retaining weatherability.” Again, see the third
full paragraph of page 2 of the specification.
As shown in figure 1 of the application, appellants
demonstrate that the gloss of a PVDF coating decreases quickly
with increasing melt viscosity when the melt viscosity is
below 35 kPoise. The gloss reduction rate decreases when the
melt viscosity exceeds 35 kPoise. As reported in the
specification at the bottom of page 9, if low gloss at 60E is
defined arbitrarily to be 15 or lower, the melt viscosity of
the PVDF resin should be at least 48 kPoise. To obtain a PVDF
paint having a gloss of 10 or lower, the resin should have a
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