Golf ball
AssigneeBridgestone Sports Co., Ltd.
InventorsAkira Kimura, Keita Iwasaki
Life of this patent
Estimating the term…
Abstract
In a golf ball having a two-layer core consisting of an inner core layer and an outer core layer and a cover of one or more layer, the inner core layer and outer core layer are each formed of a rubber composition made up primarily of a base rubber, the inner core layer has a diameter of not more than 30 mm; and the core has specific hardness ratios (JIS-C hardness/Shore D hardness) at specific points on the cross-section thereof. This golf ball has a reduced spin rate on full shots with a driver and middle irons, thus imparting to an excellent flight performance, and moreover has a good controllability in the short game on approach shots, making it ideal as a golf ball for professional golfers and mid- and high-level amateur golfers.
Claims19
A golf ball comprising a two-layer core consisting of an inner core layer and an outer core layer and a cover of one or more layer, wherein the inner core layer and outer core layer are each formed of a rubber composition made up primarily of a base rubber;
- the inner core layer has a diameter of not more than 30 mm;
- and, letting a center point in a cross-section of the two-layer core be 0% and a surface of the two-layer core be 100%, a core cross-sectional hardness ratio (JIS-C hardness/Shore D hardness) at 0% is at least 1.70 and a core cross-sectional hardness ratio (JIS-C hardness/Shore D hardness) at 100% is not more than 1.65;
- and
- wherein letting the core cross-sectional hardness ratio (JIS-C hardness/Shore D hardness) at a point 50% of the distance from the center point of the two-layer core cross-section to the core surface be T50, the value T50-T100 is at least 0.25.
A golf ball comprising a two-layer core consisting of an inner core layer and an outer core layer and a cover of one or more layer, wherein the inner core layer and outer core layer are each formed of a rubber composition made up primarily of a base rubber;
- the inner core layer has a diameter of not more than 30 mm;
- and, letting a center point in a cross-section of the two-layer core be 0% and a surface of the two-layer core be 100%, the core cross-sectional hardness ratio (JIS-C hardness/Shore D hardness) at 0% is at least 1.70 and the core cross-sectional hardness ratio (JIS-C hardness/Shore D hardness) at 100% is not more than 1.65;
- wherein the two-layer core is encased by an intermediate layer, which core and intermediate layer together comprise an intermediate layer-encased sphere, and a surface hardness of the intermediate layer-encased sphere and a surface hardness of the inner core layer have a difference therebetween, expressed in terms of JIS C hardness, which is at least 25.
Dependencies are inferred from the claim text.