Golf ball
A golf ball for amateur golfers is endowed with an excellent flight and a good feel at impact that is soft yet solid when hit by a golfer whose head speed is not very high. The ball, which includes a core and a cover, has a compressive deformation B when subjected to a final load of 30 kgf from an initial load state of 5 kgf that is from 0.72 to 0.97 mm and a compressive deformation C when subjected to a final load of 60 kgf from an initial load state of 5 kgf that is from 1.55 to 1.85 mm. In addition, the core has a hardness profile which satisfies specific conditions.
1. A golf ball comprising a core and a cover, wherein the ball has an amount of compressive deformation such that the compressive deformation B when the ball is subjected to a final load of 30 kgf from an initial load state of 5 kgf is from 0.72 to 0.97 mm and the compressive deformation C when the ball is subjected to a final load of 60 kgf from an initial load state of 5 kgf is from 1.55 to 1.85 mm, and the core has a hardness profile which, letting Cs be the Shore C hardness at a surface of the core, Cs−3 be the Shore C hardness at a position 3 mm inside the core surface and Cc be the Shore C hardness at a center of the core, satisfies formulas (1) and (2) below
Cs−Cc≥ 20 (1)
Cs−Cs− 35.0 (2)
and wherein the core is formed of a rubber composition comprising:
(a) a base rubber,
(b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid or a metal salt thereof or both,
(c) a crosslinking initiator, and
(d) a lower alcohol having a molecular weight of less than 200.
2. The golf ball of claim 1 , wherein the ball has an amount of compressive deformation such that the ratio D/C between compressive deformation C and the compressive deformation D when the ball is subjected to a final load of 130 kgf from an initial load state of 10 kgf is from 1.75 to 2.00.
3. The golf ball of claim 1 , wherein the ball has an amount of compressive deformation such that the ratio D/A between the compressive deformation D when the ball is subjected to a final load of 130 kgf from an initial load state of 10 kgf and the compressive deformation A when the ball is subjected to a final load of 5 kgf from an initial load state of 0.2 kgf is from 16.0 to 25.0.
4. The golf ball of claim 1 , wherein the content of component (d) is from 0.5 to 5 parts by weight per 100 parts by weight of the base rubber (a).
5. The golf ball of claim 1 , wherein component (d) is a monohydric, dihydric or trihydric alcohol.
6. The golf ball of claim 1 , wherein component (d) is butanol, glycerol, ethylene glycol or propylene glycol.
7. The golf ball of claim 1 , wherein the ball further comprises, between the core and the cover, at least an envelope layer and an intermediate layer, and has a construction of four or more layers that includes the core, the envelope layer, the intermediate layer and the cover.
8. The golf ball of claim 1 , wherein the cover has a coat formed on a surface thereof, which coat has a material hardness on the Shore C hardness scale of from 40 to 80.