Appeal No. 2005-1116 Page 4
Application No. 10/077,148
core 1 formed of a rubber base and a cover 4 on the core consisting of two layers, an
inner layer 2 and an outer layer 3.
Yamagishi's solid core 1 should have a specific gravity of at least 1.00, preferably
1.02 to 1.18, more preferably 1.06 to 1.15. The solid core 1 may be made of
well-known materials and formed by conventional techniques while properly adjusting
vulcanizing conditions and formulation. The core formulation may contain a base
rubber, crosslinking agent, co-crosslinking agent, and inert filler. The base rubber which
can be used is natural rubber and/or synthetic rubber used in conventional solid golf
balls. Yamagishi prefers to use 1,4-polybutadiene having at least 40% of cis-structure.
The polybutadiene may be blended with natural rubber, polyisoprene rubber,
styrene-butadiene rubber or the like, if desired. Yamagishi teaches (column 3, lines 43-
55) that:
By a proper choice of the type and amount of compounding materials,
especially crosslinking agent and co-crosslinking agent and vulcanizing
conditions, a core having a desired hardness (as expressed by a distortion under
a load of 100 kg) can be obtained. Herein, the core is preferably formed to yield a
distortion under a load of 100 kg of 2.0 to 5.0 mm, more preferably 3.0 to 4.8
mm. With a distortion falling within this range, sufficient restitution, pleasant
hitting feel, and improved scraping resistance are achievable.
Yamagishi's cover outer layer 3 is formed to a greater specific gravity than the
core 1 and the cover inner layer 2, thereby achieving a high inertia moment and
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