In a golf ball having a core and a cover of one or more layers, letting the core diameter be D (mm), the cover thickness be T (mm) and the core and ball deflections when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) be E (mm) and B (mm), the following conditions are satisfied: (1) 30D/T24, (2) 4.1E/T2.6, and (3) 1.18EIB1.09, and the core has specific hardness profile. This golf ball provides an excellent flight performance and a soft feel at impact when used by golfers whose head speed is not very fast, such as senior golfers and women golfers. The ball also has a high durability to cracking on repeated impact.

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.

A golf ball includes a core, an intermediate layer, and a cover, in which an initial velocity is not more than 76.0 m/s, a deflection when the ball is compressed under a specific load is at least 2.8 mm, and letting a value of (initial velocity of core?weight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphere?initial velocity of core)?(weight of intermediate layer-encased sphere?weight of core)] be Miw, and a value of [(initial velocity of ball?initial velocity of intermediate layer-encased sphere)?(weight of ball?weight of intermediate layer-encased sphere)] be CViw, the condition is of Ciw+Miw+CViw?2,550 is satisfied, thereby to be capable of making a distance for reducing a distance on shots with a driver and an iron by average hitters smaller.

A golf ball with a cover layer composed of a blend of (a) 20 to 99 wt % of a thermoplastic resin, and (b) 1 to 80 wt % of a high molecular weight polysiloxane having a molecular weight (Mn) of at least 10,000 and not more than about 1,000,000 (Mn,), is disclosed herein. The high molecular weight polydimethylsiloxane has blended with it 3 to 35 weight percent of a silica. The high molecular weight polydimethylsiloxane has pendant groups, terminal groups or mixtures of pendant groups and terminal groups selected from the group consisting of hydrogen, trimethyl, dimethyl, methyl, phenyl, fluoro, amino, vinyl, hydroxyl, and methacrylate.

Multi-layered golf ball core sub-assemblies and the resulting golf balls are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The intermediate and outer core layers are preferably formed from foamed and non-foamed thermoset compositions. For example, the intermediate core can be formed from a thermoset rubber so there are adjoining foam core layers (inner and intermediate) and the outer core layer can be formed from a non-foamed thermoset rubber. The core layers have different hardness and specific gravity levels. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency.

In a multi-piece solid golf ball having a core, a cover and an intermediate layer therebetween, the core, an intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, and the intermediate layer and the cover have thicknesses which satisfy a specific relationship. Also, the core has a hardness profile in which the hardnesses at the core surface, core center, a position 5 mm from the core center, and a position midway between the surface and center of the core satisfy specific relationships. This golf ball, when used by mid- and high-level amateurs, enables the golfer to maintain an adequate distance on shots with a driver and achieve a good distance on iron shots, has a good spin performance on approach shots and has a good feel on impact. In addition, the ball has an excellent scuff resistance when struck with a grooved wedge.

In a multi-piece solid golf ball made up of, successively, a core, an intermediate layer and a cover having numerous dimples on the surface thereof, the intermediate layer is formed of a resin material and the cover is formed of a urethane resin material, each having a specific respective Shore D hardness. The ball has a specific (intermediate layer thickness)/(core diameter) value and a specific (cover thickness)/(core diameter) value, and the core has a specific deflection. The sphere consisting of the core encased by the intermediate layer has an initial velocity A and the core has an initial velocity B which together satisfy the condition AB0 m/s. This golf ball provides an increased distance and has both a soft feel when played and a high durability to repeated 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 core?weight of core) be Ciw, a value of [(initial velocity of intermediate layer-encased sphere-initial velocity of core)?(weight of intermediate layer-encased sphere-weight of core)] be Miw, and a value of [(initial velocity of ball-initial velocity of intermediate layer-encased sphere)?(weight of ball-weight of intermediate layer-encased sphere)] be CViw, the following condition is satisfied:

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

Lift coefficients and drag coefficients at predetermined Reynolds numbers and spin rates are set to predetermined ranges.

In a multi-piece solid golf ball having a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and an outermost layer encasing the intermediate layer, the envelope layer-encased sphere, the intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, the intermediate layer and the cover have thicknesses which satisfy a specific relationship, and the core has a hardness profile in which the hardnesses at the core surface, core center, a position 5 mm from the core center, and a position midway between the core surface and center satisfy specific relationships. This golf ball satisfies at a high level the flight and control performances desired for use by professional golfers and skilled amateurs. In particular, it holds down the spin rate on full shots and follows a straight trajectory, thus having a superior flight performance, and moreover is endowed with an excellent scuff resistance.

In a golf ball having a core and a cover of one or more layers, letting the core diameter be D (mm), the cover thickness be T (mm) and the core and ball deflections when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) be E (mm) and B (mm), the following conditions are satisfied: (1) 30D/T24, (2) 4.1E/T2.6, and (3) 1.18EIB1.09, and the core has specific hardness profile. This golf ball provides an excellent flight performance and a soft feel at impact when used by golfers whose head speed is not very fast, such as senior golfers and women golfers. The ball also has a high durability to cracking on repeated impact.