An object of the present invention is to provide a golf ball excellent in flying performance, in particular, to provide a golf ball traveling a great flight distance. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d1) an aromatic carboxylic acid or (d2) an aromatic carboxylic acid salt, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the ,-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

In a golf ball having a core and a cover of at least one layer encasing the core, the core is formed of a rubber composition which includes (a) a base rubber, (b) a co-crosslinking agent which is an ,-unsaturated carboxylic acid and/or a metal salt thereof, (c) a filler, and (d) a crosslinking initiator, and the base rubber (a) has a polybutadiene content of at least 90 wt % and a syndiotactic 1,2-polybutadiene content of from 5 to 30 wt %, the amount of filler (c) included is from 6 to 14 vol % of the rubber composition, and the ball has a specific gravity of 1.0 or more and an initial velocity of 75 m/s or less, as the result of which the golf ball maintains a low rebound, undergoes little change in properties due to changes in temperature and has an excellent durability.

In a golf ball including a core, an intermediate layer, and a cover, the relationship of the surface hardness between an intermediate layer-encased sphere and the ball satisfies a predetermined relational expression, and with an initial velocity of the ball and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of coreweight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphereinitial velocity of core)(weight of intermediate layer-encased sphereweight of core)] be Miw, and a value of [(initial velocity of ballinitial velocity of intermediate layer-encased sphere)(weight of ballweight of intermediate layer-encased sphere)] be CViw, the expression of Ciw+Miw+CViw is optimized, and lift and drag coefficients at predetermined Reynolds numbers and spin rates of dimples are set to predetermined ranges.

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.

Provided is a golf ball including a core, an intermediate layer, and a cover. A relationship between surface hardnesses of an intermediate layer-encased sphere and the ball satisfies a predetermined relational expression. With a ball initial velocity and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of coreweight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphereinitial velocity of core)(weight of intermediate layer-encased sphereweight of core)] be Miw, and a value of [(initial velocity of ballinitial velocity of intermediate layer-encased sphere)(weight of ballweight of intermediate layer-encased sphere)] be CViw, the following condition is satisfied: $2500\mathrm{Ciw}+\mathrm{Miw}+\mathrm{CViw}2650.$ Lift coefficients and drag coefficients at predetermined Reynolds numbers and spin rates are set to predetermined ranges.

The golf ball includes a core having an inner layer core and an outer layer core, a single-layered intermediate layer and cover, wherein the inner layer core is formed of a rubber composition, the intermediate layer and the cover are formed of a resin composition, and a relationship between an initial velocity of the inner layer core, an initial velocity of the entire core, an initial velocity of an intermediate layer-encased sphere, and an initial velocity of a ball satisfies the following conditions:
(initial velocity of ball)<(initial velocity of intermediate layer-encased sphere)
(initial velocity of intermediate layer-encased sphere)(initial velocity of entire core)0.70 (m/s)
(initial velocity of entire core)(initial velocity of inner layer core)0.20 (m/s) and a specific gravity of the intermediate layer and a deflection of the golf ball when compressed under a predetermined load are set within specific ranges.

Provided is a golf ball including a core, an intermediate layer, and a cover. A relationship between surface hardness of an intermediate layer-encased sphere and surface hardness of the ball satisfies a predetermined relational expression. With an initial velocity of the ball and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of coreweight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphereinitial velocity of core)(weight of intermediate layer-encased sphereweight of core)] be Miw, and a value of [(initial velocity of ballinitial velocity of intermediate layer-encased sphere)(weight of ballweight of intermediate layer-encased sphere)] be CViw, the following expression is satisfied:
2500Ciw+Miw+CViw2650. A volume occupancy ratio of dimples is set to a predetermined range.

In a golf ball having a core, an intermediate layer and a cover, the ball and the sphere obtained by encasing the core with the intermediate layer have respective surface hardnesses such that (surface hardness of ball)<(surface hardness of intermediate layer-encased sphere); the ball has an initial velocity of 75.0 m/s; and the core has a hardness profile in which the center hardness, the hardness at a midpoint between the core center and core surface, and the hardnesses at specific positions inward from the midpoint and at specific positions outward from the midpoint are optimized. Given the possibility that the rules limiting the distance traveled by a golf ball on shots by long hitters will change, this ball reduces the drop-off in distance on driver shots and iron shots taken by average hitters while increasing the drop-off in distance on driver shots taken by long hitters.

A golf ball includes a core and a cover, in which a large number of dimples are formed on an outside surface of the cover, the cover is formed using an ionomer resin as a chief material, an initial velocity of the ball is set within a predetermined range, a deflection when a predetermined load is applied to the ball is set within a predetermined range, a relationship of a ratio to a lift coefficient/drag coefficient at a Reynolds number of 218,000 and a spin rate of 2,800 rpm, a lift coefficient/drag coefficient at a Reynolds number of 184,000 and a spin rate of 2,900 rpm, and a lift coefficient/drag coefficient at a Reynolds number of 158,000 and a spin rate of 3,100 rpm is specified, and a volume occupancy ratio of the dimples is set within a predetermined range.

Provided is a golf ball including a core, an intermediate layer, and a cover. A relationship between surface hardnesses of an intermediate layer-encased sphere and the ball satisfies a predetermined relational expression. With a ball initial velocity and a deflection under a predetermined load applied to the ball optimized, and letting a value of (initial velocity of coreweight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphereinitial velocity of core)(weight of intermediate layer-encased sphereweight of core)] be Miw, and a value of [(initial velocity of ballinitial velocity of intermediate layer-encased sphere)(weight of ballweight of intermediate layer-encased sphere)] be CViw, the following condition is satisfied:

[00001]$2500\mathrm{Ciw}+\mathrm{Miw}+\mathrm{CViw}2650,$

wherein a total volume of the dimples is from 306 to 363 mm.sup.3.