Multi-piece solid golf ball
AssigneeBridgestone Sports Co., Ltd.
InventorsHideo Watanabe, Masanobu Kuwahara
Life of this patent
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Abstract
In a golf ball having a core, an envelope layer, an intermediate layer and a cover, the difference between the center hardness and the surface hardness of the core is set in a specific range, the intermediate layer is formed of a resin material that includes a high-acid ionomer, the Shore C hardness relationships among the core center and the surfaces of the envelope-encased layer and the intermediate layer-encased sphere satisfy specific conditions; and the ball has a deflection when compressed under a given load which is at least 2.7 mm. This ball achieves a good distance on shots with a driver, utility club or iron, is receptive to spin in the short game, and has a soft feel at impact on all shots, making it useful to amateur golfers.
Claims9
A multi-piece solid golf ball comprising a core, an envelope layer, an intermediate layer and a cover, the core being formed of a rubber composition as one layer, the envelope layer being formed of a resin material as one or more layers and the intermediate layer and cover each independently being formed of a resin material as a single layer,
- wherein
- the core has a surface hardness and a center hardness on the Shore C hardness scale with a difference therebetween of at least 20;
- the resin material making up the intermediate layer contains a high-acid ionomer;
- the center hardness of the core, surface hardness of the sphere obtained by encasing the core with the envelope layer (envelope layer-encased sphere) and surface hardness of the sphere obtained by encasing the envelope layer-encased sphere with the intermediate layer (intermediate layer-encased sphere) have Shore C hardness relationships therebetween which satisfy the following conditions:
- surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere, and (1)
- (surface hardness of intermediate layer-encased sphere)−(center hardness of core)≥40;
- (2)
- and the ball has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) which is at least 2.7 mm, and
- wherein the core has a diameter of from 35.1 to 41.3 mm, and
- the core has a hardness profile in which, letting Cc be the Shore C hardness at the core center, Cm be the Shore C hardness at a midpoint M between the core center and the core surface, Cm−2, Cm−4 and Cm−6 be the respective Shore C hardnesses at positions 2 mm, 4 mm and 6 mm inward from the midpoint M, Cm+2, Cm+4 and Cm+6 be the respective Shore C hardnesses at positions 2 mm, 4 mm and 6 mm outward from the midpoint M and Cs be the Shore C hardness at the core surface, and defining the surface areas A to F as follows
- surface area A:
- 1/2×2×(Cm−4−Cm−6)
- surface area B:
- 1/2×2×(Cm−2−Cm−4)
- surface area C:
- 1/2×2×(Cm−Cm−2)
- surface area D:
- 1/2×2×(Cm+2−Cm)
- surface area E:
- 1/2×2×(Cm+4−Cm+2)
- surface area F:
- 1/2×2×(Cm+6−Cm+4),
- (surface area E+surface area F)−(surface area A+surface area B) has a value of 2.0 or more.
Dependencies are inferred from the claim text.