Appeal 2007-1895
Application 10/719,489
containing silicone rubber composition comprising forming a flowable
organosiloxane powder composition by blending a high consistency or
liquid polydiorganosiloxane and a filler to which a curing agent is added and
the powder composition massed (Bilgrien, e.g., Abstract and col. 2,
ll. 7-33). The blending step is performed in any mixer apparatus which
applies shearing forces to reduce particle size at a temperature of greater
than 100°C up to 200°C (id., e.g., col. 2, ll. 22-28, col. 2, l. 37, to col. 3,
l. 21, col. 6, l. 41, to col. 7, l. 6, and col. 7, ll. 31-66). “The blending of the
powder with the curing agent, curing catalyst and subsequent massing of the
powder composition are conducted at temperatures below about 40°C. to
maximize the working time of the composition” (id. col. 9, l. 41, to col. 10, l.
30). Bilgrien discloses that subsequent to blending the powder composition,
either of two options are available. The first option includes
heating of the reactor is discontinued while the plow and
chopper blades are rotated until the temperature of the product
decreases to 60 degrees or less. Continuation of mixing as the
product cools ensures uniformity of the final powder. The
cooled material then can be discharged from the mixer. The
second option involves simply discharging the hot material
from the mixer.
Id. col. 9, ll. 20-33. Bilgrien illustrates the first option in Example 1 in that
after steam was circulated in the jacket of the mixer to maintain a chamber
temperature of 140° to 145°C, “cooling water was circulated through the
jacket of the mixer chamber and operation of the plow and chopper blades
continued until the temperature of the material in the chamber reached
60°C” (id. col. 13, ll. 26-42). Bilgrien further illustrates in Examples 2 and 3
that after mixing, the powder composition in the mixer chamber was
“transferred to a container” or “discharged into a receiving container” (id.,
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