Appeal No. 94-4489
Application No. 07/857,216
These microspheres are resilient and thus impart
good compressibility properties to the layer.
Appellants then go on to state (see the paragraph bridging
pages 4 and 5 of the specification) that:
However, in prior art methods of producing a
compressible layer employing thermoplastic
microspheres for a printing blanket, it has been
found that the thickness of the compressible layer
to be formed is not easily controlled since typical
thermoplastic microspheres will melt at normal
processing and vulcanizing temperatures. Since the
microspheres melt before the vulcanization is
complete, and before the compressible layer achieves
a set structure, agglomeration of the voids created
by the microspheres occurs, and size variations in
the voids also occur. This can affect the overall
performance properties of the blanket. Also, the
variations in the sizes of the voids can weaken the
printing blanket, causing it to wear out
prematurely.
To avoid the melting of thermoplastic microspheres during
vulcanization, appellants employ thermoplastic microspheres
having a higher melting temperature, i.e., a temperature
higher than vulcanization temperatures, in a process for
forming a compressible printing blanket. Specifically, the
claimed process requires employing “thermoplastic microspheres
having a melting temperature of 135°C or above” and a
vulcanizing temperature of 80-150°C . See claim 1.
Appellants acknowledge (Brief, page 5) that:
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