In a golf ball having a core, a cover and at least one intermediate layer between the core and the cover, the core is made of a material molded under heat from a rubber composition that includes (a) a base rubber, (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid and/or a metal salt thereof, (c) an organic peroxide, (d) water, and (e) an antioxidant which is a benzimidazole of a specific formula and/or a metal salt thereof. The core and ball have compressive deformations within specific respective ranges when subjected to given loading conditions. This golf ball exhibits a low spin rate on shots, enabling the flight performance of the ball to be improved.

Multi-layered golf balls having at least one layer made of a foamed silicone composition are provided. Multi-layered golf balls having at least one layer made of non-foamed silicone elastomer composition also are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The foamed silicones have good thermal stability and durability without sacrificing resiliency. The non-foamed silicone elastomers have high elongation, tensile strength, chemical/fluid-resistance, and weatherability properties. These compositions can be used to form any layer, for example, core, intermediate, or cover, in the golf ball.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core is formed of a rubber composition, the envelope layer, intermediate layer and cover are each formed of a single layer of resin material; the hardness relationship among the layers, in terms of Shore C hardness values, satisfies the following two conditions:

material hardness of cover>material hardness of intermediate layer, and

material hardness of envelope layer≥surface hardness of core; and

the thickness relationship among the layers satisfies the following condition:

(cover thickness intermediate layer thickness)<envelope layer thickness.

This ball serves as a distance ball which enables a superior distance to be achieved on full shots with a driver and with irons.

In a golf ball having a core, envelope layer, intermediate layer and cover, the (core diameter)/(ball diameter) value falls within a particular range, the core has a specific hardness profile, and the Shore C hardness relationships among the core center and surface hardnesses and the surface hardnesses of the envelope layer-encased sphere, intermediate layer-encased sphere and ball satisfy the following conditions:
core surface hardness<surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness,  (1)
(surface hardness of envelope layer-encased sphere)−(core center hardness)≥28.  (2)
Also, the envelope layer, intermediate layer and cover have respective thicknesses which satisfy the condition:
cover thickness<intermediate layer thickness  (3)
cover thickness<envelope layer thickness  (4)
envelope layer thickness≥0.8 mm.  (5)
This ball enables mid-level and skilled amateur golfers to achieve superior distances on driver shots and on iron shots, and moreover has a soft yet good feel at impact.

Multi-layered golf balls having at least one layer made of a foamed silicone composition are provided. Multi-layered golf balls having at least one layer made of non-foamed silicone elastomer composition also are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The foamed silicones have good thermal stability and durability without sacrificing resiliency. The non-foamed silicone elastomers have high elongation, tensile strength, chemical/fluid-resistance, and weatherability properties. These compositions can be used to form any layer, for example, core, intermediate, or cover, in the golf ball.

Multi-layered golf balls having at least one layer made from silicone (polysiloxane) elastomers; silicone (polysiloxane) elastomer/polyurethane blends; polycarbonate-polysiloxane blends and copolymers; and polycarbonate-polysiloxane/polyurethane blends are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The polysiloxane compositions have good thermal stability and durability without sacrificing resiliency. The polysiloxane compositions also have high elongation, tensile strength, chemical/fluid-resistance, and weatherability properties. These compositions can be used to form any layer, for example, core, intermediate, or cover, in the golf ball.

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 specific conditions, the core and the ball have respective deflections which satisfy certain conditions and the core has a specific internal hardness profile.

A golf ball is provided which suppresses twisting due to external forces while maintaining sufficient deflection at the time of impact, reduces the spin rate without lowering ball rebound, and is thus able to effectively increase the distance traveled by the ball, particularly on shots with a driver. In the golf ball, which includes a core and a cover, the core has a core body made of a first polybutadiene rubber and having a surface with a plurality of groves or holes thereon, which grooves or holes are filled with a second polybutadiene rubber of a differing composition from the first polybutadiene rubber. The polybutadiene rubber-filled groove portions or hole portions have a higher surface hardness than the core body.

Multi-piece golf balls containing a dual-layered core are provided. The ball further includes single or multi-layered covers. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, and a surrounding outer core layer. The core layers may have different hardness gradients. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and combinations and alloys thereof preferably dispersed in a thermoplastic polymeric matrix. The outer core layer is preferably formed from a thermoset composition such as polybutadiene. These multi-layered core constructions with metal-containing centers have selective specific gravity relationships between the different layers. This helps provide the ball with good flight distance and spin control. The resulting balls have good resiliency and other playing performance properties.

Multi-layer golf balls having a hard, high compression center, a relatively soft intermediate layer, and a stiff outer cover layer, are provided. The outer surface hardness of the intermediate layer is less than that of both the center and the outer cover layer.