Provided is a golf ball comprising a spherical core including an inner layer and an outer layer, an intermediate layer and a cover, wherein a difference (H.sub.X+1H.sub.X1) 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 of a hardness gradient of the inner layer is 0 or more, a difference () between the angle and an angle of a hardness gradient of the outer layer is 0 or more, the intermediate layer has a material hardness (Hm) ranging from 65 to 80 in Shore D hardness, and the intermediate layer has a highest hardness among the constituent members of the golf ball.

A formulation for making at least one element of a golf ball, wherein the formulation includes: (i) from 50 weight percent to 95 weight percent of a thermoplastic composition comprising: (1) at least one ethylene acid copolymer consisting essentially of copolymerized comonomers of: (A) ethylene, and (B) from 5 weight percent to 25 weight percent of at least one ,-ethylenically unsaturated carboxylic acid having from 3 carbon atoms to 8 carbon atoms, based on the total weight of monomers present in the ethylene acid copolymer; wherein the acid moieties of component (1) are neutralized to a level of from 25 percent to 220 percent; and (ii) from 5 weight percent to 50 weight percent of a crosslinked material having a gel content of at least 80 weight percent, wherein the crosslinked material is a crosslinked elastomer, a crosslinked rubber, or a blend of a crosslinked elastomer and a crosslinked rubber; a process for making the above formulation; at least one element of a multilayer golf ball and a process for making the at least one element of a multilayer golf ball using the above formulation; a multilayer golf ball including (a) at least one core, and (b) a cover; wherein the at least one core is made from the above formulation; and a process of manufacturing the above multilayer golf ball.

The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, the core being 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. The core has a hardness profile which satisfies specific relationships between the JIS-C hardness at the core center (Cc), the JIS-C hardness at a position 10 mm from the core center (C10) and the JIS-C hardness at the core surface (Cs).

A golf ball comprising: (a) a core; (b) an inner mantle layer; (c) an intermediate mantle layer; (d) an outer mantle layer; and (e) at least one cover layer; wherein the core has a PGA compression of less than 70, and the core/inner mantle layer/intermediate mantle layer combined construct has a PGA compression of at least 30.

Multi-piece golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The outer core layer is preferably formed from a non-foamed thermoset composition such as polybutadiene rubber. The inner and outer core layers can have different hardness gradients. Preferably, the specific gravity (density) of the foam inner core is less than the density of the outer core layer. The ball further includes a cover of at least one layer and may include at least one casing layer. The core structure and resulting ball have relatively good resiliency.

Multi-layered golf balls containing a two or three-layered cover assembly are provided. In one embodiment, the cover assembly includes a relatively hard inner cover and relatively soft outer cover. Alternatively, the cover assembly may include a relatively soft inner cover with a relatively hard outer cover. Three-layered covers comprising an inner cover, intermediate cover, and outer cover layer also may be prepared. Preferably, at least one of the layers is formed from a thermoplastic composition that preferably 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 cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

The invention provides a golf ball having a core and a cover of at least one layer. The core has a cross-sectional hardness which, letting R (mm) be the radius of the core, A be the JIS-C hardness at a center of the core, B be the JIS-C hardness at a position R/3 mm from the core center, C be the JIS-C hardness at a position R/1.8 mm from the core center, D be the JIS-C hardness at a position R/1.3 mm from the core center, and E be the JIS-C hardness at a surface of the core, satisfies the formulas (1) DC7, (2) CB7, (3) (DC)(CB)7, and (4) EA16.

An object of the present invention is to provide a golf ball having an excellent initial velocity when being hit at a head speed of 50 m/sec and an improved initial velocity when being hit at a head speed of 40 m/sec. The present invention provides a golf ball comprising a spherical core and at least one cover covering the spherical core, wherein the spherical core is formed from a core rubber composition containing (a) a base rubber, (b) a co-crosslinking agent, (c) a crosslinking initiator and (x) a crosslinked rubber powder, and (x) the crosslinked rubber powder is formed from a rubber composition containing (a1) a base rubber, (b1) a co-crosslinking agent, (c1) a crosslinking initiator and (r) a resin component.

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The outer core layer is preferably formed from a non-foamed composition selected from thermoset compositions and thermoplastic compositions. The core layers have different hardness and specific gravity levels. The specific gravity (density) of the foam inner core is preferably less than the density of the outer core layer.

Golf balls having a single or dual-layered solid core are provided. In one embodiment, the golf ball has dimensions and properties that do not conform to the rules of the United States Golf Association (USGA). For example, the ball weight; ball size; ball spherical symmetry; ball initial velocity; and/or ball overall distance may fall outside of the USGA standards. The dual-layered core can have an inner core comprising a thermoplastic composition and surrounding outer core comprising a thermoset composition. In another embodiment, the dual-layered core has an inner core comprising a thermoplastic composition and outer core comprising a thermoset composition. The thermoplastic composition preferably comprises an ethylene acid copolymer ionomer and plasticizer. The thermoset composition preferably comprises polybutadiene rubber. The ball further includes a cover of at least one layer.