Golf ball and method of manufacture
AssigneeBridgestone Sports Co., Ltd.
InventorTsuyoshi Nakajima
Life of this patent
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Abstract
In a golf ball having a core and a cover, the core is formed of a rubber composition, has center and surface portions which are unfoamed regions and has an intermediate portion containing a foamed region. The core is produced by charging the rubber composition, which contains a blowing agent, into a first curing mold and curing under given conditions, then removing the molded rubber material in a semi-cured state from the first mold, transferring the semi-cured material to a second curing mold and curing under given conditions. The foamed region of the core deforms by a certain degree at the time of impact, decreasing the radius of gyration of the ball and enabling a lower spin rate to be achieved. The decrease in resilience due to expansion of the molded material can be held to a minimum.
Claims8
A golf ball comprising a core and a cover of one or more layer encasing the core, wherein the core is formed of a rubber composition comprising a base rubber, a co-crosslinking agent, an organic peroxide and a blowing agent, has a center portion and a surface portion that are unfoamed regions, and has an intermediate portion containing a foamed region.
A method of manufacturing a golf ball having a core and a cover of one or more layer encasing the core, which core is a cured and molded material produced using a first curing mold having a cavity with an inside diameter ø1 and a second curing mold having a cavity with an inside diameter ø2 such that ø1<ø2, the method comprising:
- (a) a first curing step of charging a rubber composition containing a blowing agent into the first curing mold and applying heat and pressure under given temperature and time conditions;
- and
- (b) a second curing step of removing the molded rubber material in a semi-cured state from the first curing mold following the first curing step, transferring the semi-cured material to the second curing mold and applying heat and pressure under given temperature and time conditions,
- wherein the cured and molded material has a center portion and a surface portion that are unfoamed regions and has an intermediate portion containing a foamed region.
Dependencies are inferred from the claim text.