An object of the present invention is to provide a golf ball traveling a great distance on driver shots. The present invention provides a golf ball comprising a spherical core including an inner layer and an outer layer, wherein a difference (H.sub.X+1−H.sub.X−1) between a hardness (H.sub.X+1) at a point outwardly away in a radial direction from a boundary between the inner layer and the outer layer of the spherical core by 1 mm and a hardness (H.sub.X−1) at a point inwardly away in the radial direction from the boundary between the inner layer and the outer layer of the spherical core by 1 mm is 0 or more in Shore C hardness, a surface hardness (H.sub.X+Y) of the spherical core is more than 70 in Shore C hardness, an angle α of a hardness gradient of the inner layer is 0° or more, a difference (α−β) between the angle α and an angle β of a hardness gradient of the outer layer is 0° or more, and the intermediate layer has a highest hardness among the constituent members of the golf ball.

Buoyant dimpled golf ball having CoR ≥0.810, specific gravity <1.00 g/cc, initial velocity ≥250 ft/s, first aerodynamic coefficient magnitude between about 0.25 and about 0.30 and first aerodynamic force angle between about 29 degrees and 34 degrees at Reynolds Number of 230000 and spin ratio of 0.085; and second aerodynamic coefficient magnitude between about 0.26 and about 0.31 and second aerodynamic force angle between about 31 degrees and 36 degrees at Reynolds Number of 180000 and spin ratio of 0.101. Golf ball may additionally have third aerodynamic coefficient magnitude between about 0.27 and about 0.32 and third aerodynamic force angle between about 34 degrees and 39 degrees at Reynolds Number of 133000 and spin ratio of 0.133; and fourth aerodynamic coefficient magnitude between about 0.33 and about 0.38 and fourth aerodynamic force angle between about 38 degrees and 43 degrees at Reynolds Number of 89000 and spin ratio of 0.183.

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.

Methods for making multi-piece golf balls having an outer cover, intermediate, or other layer comprising a heterogeneous composition are provided. The heterogeneous composition comprises a mixture of Compounds A and B. For example, the compounds can be different polyurethanes, ethylene acid copolymer ionomers, polyesters, polyamides, or any other suitable materials for making golf ball layers. Compounds having different hardness levels can be used. For example, the composition can comprise a mixture of hard and soft materials. The invention also encompasses golf balls made from such methods. The golf balls have good resiliency and impact durability along with other optimum playing performance properties.

A golf ball is provided that achieves a satisfactory distance on full shots with an iron, is superior in the short game, and has a good feel at impact and a good durability. The golf ball has a core formed of a rubber composition as one or more layer, an envelope layer formed of a resin material as one or more layer, an intermediate layer formed of a resin material as one layer, and a cover formed of a resin material as one layer having a thickness of not more than 1.0 mm. The layers of the ball have Shore C hardnesses at the respective surfaces thereof which together satisfy certain conditions, and the core and the ball have respective deflections which satisfy certain other conditions.

A golf ball is provided that achieves a satisfactory distance on full shots with a driver and an iron, is superior in the short game, and has a good feel at impact and a good durability. The golf ball has a core formed of a rubber composition as one or more layer, an inner envelope layer formed of a resin material as one or more layer, an outer envelope layer and intermediate layer which are each formed of a resin material as one layer, and a cover formed of a resin material as one layer having a thickness of not more than 1.0 mm. The inner envelope layer-encased sphere, outer envelope layer-encased sphere, intermediate layer-encased sphere and ball have Shore C hardnesses at the respective surfaces thereof which together satisfy certain conditions, and the ball has at least a given deflection under specific loading conditions.

Golf balls having a multi-layered core made of a foamed composition are provided. The core preferably has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. Preferably, a polyurethane foam composition is used to form the foam center. The foam inner core preferably includes a fully-foamed center region and a partially or completely-collapsed foam outer region. The hardness of the fully-foamed region is different than the hardness of the collapsed foam region. Non-foamed thermoset or thermoplastic materials such as polybutadiene rubbers or ethylene acid copolymer ionomer may be used to form the outer core layer. The ball further includes a cover that may be multi-layered. The foam cores have good resiliency.

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.

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, the cover is formed of a urethane resin material, the core has a diameter of at least 38.0 mm, the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of at least 3.9 mm, the core has a center and a surface such that the value obtained by subtracting the JIS-C hardness at the core center from the JIS-C hardness at the core surface is at least 15, 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.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core, an intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, and the envelope layer, 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.