Patent ID: 11938378
Assignee: BRIDGESTONE SPORTS CO., LTD.
Field: Furniture, games (Other fields)
Classification: CPC A | IPC A

Claim 0:
1. 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 diameter of from 35.1 to 41.3 mm;
the core has a hardness profile in which, letting Cc be the Shore C hardness at a center of the core, Cm be the Shore C hardness at a midpoint M between the core center and a surface of the core, 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: ½×2×(Cm−4−Cm−6)
surface area B: ½×2×(Cm−2−Cm−4)
surface area C: ½×2×(Cm−Cm−2)
surface area D: ½×2×(Cm+2−Cm)
surface area E: ½×2×(Cm+4−Cm+2)
surface area F: ½×2×(Cm+6−Cm+4),

(surface area E+surface area F)−(surface area A+surface area B) has a value of 1.0 or more;
the intermediate layer has a material hardness on the Shore D hardness scale of at least 65 and has a specific gravity of at least 1.05,
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)