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.

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) made from a foam or metal-containing composition, or it has a hollow shell construction, and the outer core layer is made of a thermoplastic composition. Preferably, the thermoplastic composition comprises: a) ethylene acid copolymer, b) plasticizer, and c) cation source. A fatty acid ester such as ethyl oleate is preferably used as the plasticizer. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency at given compressions.

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.

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.

In a multi-piece solid golf ball having a core, an intermediate layer encasing the core and a cover which encases the intermediate layer and has numerous dimples on an outside surface thereof, the intermediate layer is formed of a resin material comprising an ionomer resin as a base resin and an inorganic granular filler, the cover is formed of a urethane resin material, the core has a diameter of at least 38.0 mm, the core has specific deflection, the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) has a surface hardness on the Shore D hardness scale of at least 69, the ball has a surface hardness on the Shore D hardness scale of 62 or less, and the (intermediate layer thickness)/(core diameter) value is from 0.025 to 0.043, the (cover thickness)/(core diameter) value is from 0.014 to 0.027.

The golf ball includes a core, an intermediate layer, and a cover, in which the core is formed of a rubber composition into a single layer or a plurality of layers, the intermediate layer and the cover are both formed of a single-layer resin composition, and a relationship between an initial velocity of the core, an initial velocity of a sphere (intermediate layer-encased sphere) in which the core is encased with the intermediate layer, and an initial velocity of a sphere (ball) in which the intermediate layer-encased sphere is encased with the cover satisfies the following two conditions:

(initial velocity of ball)<(initial velocity of intermediate layer-encased sphere)

0.60?(initial velocity of intermediate layer-encased sphere)?(initial velocity of core)?1.00 (m/s). and the specific deflection is 3.00 mm or less, and a specific gravity of the intermediate layer is 1.05 or more.

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 golf ball having a two-layer core consisting of an inner core layer and an outer core layer, an intermediate layer and a cover, the core is formed primarily of a base rubber, the diameter of the inner core layer is at least 21 mm, the intermediate layer and cover are each formed primarily of a resin material, the overall core has a specific hardness profile, the inner core layer has a higher specific gravity than the outer core layer, and the sphere consisting of the core encased by the intermediate layer has a higher surface hardness than the ball. This golf ball has a high initial velocity at impact while holding down the spin rate on full shots with a driver or long iron, enabling a good distance to be achieved. The ball also has a good controllability in the short game.

The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, wherein the core is formed of a material molded under heat from a rubber composition containing (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate, and has a hysteresis loss of 50% or less when compressed at a load cell speed of 500 mm/min and under a constant load of 5,000 N.