Multi-piece solid golf ball
In a golf ball having a core, an envelope layer, an intermediate layer and a cover, the core is formed of a rubber composition and the envelope layer, the intermediate layer and the cover are each formed of a resin composition. The core, the envelope layer-encased sphere, the intermediate layer-encased sphere and the ball have respective initial velocities which together satisfy the following three conditions: (initial velocity of ball)<(initial velocity of intermediate layer-encased sphere), (initial velocity of intermediate layer-encased sphere)−(initial velocity of envelope layer-encased sphere)≤0.60 m/s, and 0.50≤(initial velocity of envelope layer-encased sphere)−(initial velocity of core)≤1.08 m/s. This golf ball can achieve a superior distance on shots with a utility club and with irons, and exhibits a good durability to repeated impact, a good controllability in the short game and a good feel at impact.
1. A multi-piece solid golf ball comprising a core of one or more layer, one or more envelope layer, a single intermediate layer and a single-layer cover, wherein the core is formed of a rubber composition, the envelope layer, the intermediate layer and the cover are each formed of a resin composition, and the core has an initial velocity, the envelope layer-encased sphere obtained by encasing the core with the envelope layer has an initial velocity, the intermediate layer-encased sphere obtained by encasing the envelope layer encased sphere with the intermediate layer has an initial velocity and the ball obtained by encasing the intermediate layer-encased sphere with the cover has an initial velocity which together satisfy the following three conditions:
(initial velocity of ball)<(initial velocity of intermediate layer-encased sphere),
(initial velocity of intermediate layer-encased sphere)−(initial velocity of envelope layer-encased sphere)≤0.60 m/s, and
0.50≤(initial velocity of envelope layer-encased sphere)−(initial velocity of core)≤1.08 m/s, and
wherein the ball satisfies the following condition:
Shore C surface hardness of ball <Shore C surface hardness of intermediate layer encased sphere >Shore C surface hardness of envelope layer-encased sphere >Shore C surface hardness of core.
2. The golf ball of claim 1 , wherein the resin composition of the intermediate layer includes a high-acid ionomer resin having an acid content of 16 wt % or more.
3. The golf ball of claim 1 , wherein the intermediate layer has a specific gravity of 1.05 or more.
4. The golf ball of claim 1 , wherein the intermediate layer includes a granular inorganic filler.
5. The golf ball of claim 1 , wherein the cover and the intermediate layer have respective specific gravities with a difference therebetween of not more than 0.15.
6. The golf ball of claim 1 , wherein the ball satisfies the following condition:
thickness of cover <thickness of intermediate layer≤thickness of envelope layer.
7. The golf ball of claim 1 , wherein the core has a diameter of from 35.1 to 41.3 mm.
8. The golf ball of claim 1 , wherein the core has a hardness profile in which, letting Cc be the Shore C hardness at a center of the core, Cs be the Shore C hardness at a surface of the core, 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 and 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 defining 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), the core satisfies the condition:
(surface area E+surface area F)−(surface area A+surface area B)≥1.0.
9. The golf ball of claim 1 , wherein the ball satisfies the following condition:
1.00≤(initial velocity of intermediate layer-encased sphere)−(initial velocity of core)≤1.65 m/s.
10. A multi-piece solid golf ball comprising a core of one or more layer, one or more envelope layer, a single intermediate layer and a single-layer cover, wherein the core is formed of a rubber composition, the envelope layer, the intermediate layer and the cover are each formed of a resin composition, and the core has an initial velocity, the envelope layer-encased sphere obtained by encasing the core with the envelope layer has an initial velocity, the intermediate layer-encased sphere obtained by encasing the envelope layer encased sphere with the intermediate layer has an initial velocity and the ball obtained by encasing the intermediate layer-encased sphere with the cover has an initial velocity which together satisfy the following three conditions:
(initial velocity of ball)<(initial velocity of intermediate layer-encased sphere),
(initial velocity of intermediate layer-encased sphere)−(initial velocity of envelope layer-encased sphere)≤0.60 m/s, and
0.50≤(initial velocity of envelope layer-encased sphere)−(initial velocity of core)≤1.08 m/s, and
wherein the core has a hardness profile in which, letting Cc be the Shore C hardness at a center of the core, Cs be the Shore C hardness at a surface of the core, 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 and 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 defining 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),
the core satisfies the condition:
(surface area E+surface area F)−(surface area A+surface area B)≥1.0.
11. The golf ball of claim 10 , wherein the core has a diameter of from 35.1 to 41.3 mm.