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.

An object of the present disclosure is to provide a golf ball having a small difference in the flight distance on a driver shot when hit at a high head speed and when hit at a low head speed. The present disclosure provides a golf ball comprising a spherical core, an intermediate layer and an outermost cover, wherein when a center hardness Ho (Shore C hardness) of the spherical core, a surface hardness Hs (Shore C hardness) of the spherical core, a hardness difference S=HsHo, a material hardness Hm (Shore D hardness) of the intermediate layer, a material hardness Hc (Shore D hardness) of the outermost cover, a thickness Tc (mm) of the outermost cover, and a total lower volume Vi (mm.sup.3) of a plurality of dimples satisfy Vi>365 and (Hc/Tc)(SHm/Vi)130.

An object of the present disclosure is to provide a golf ball that has a high spin rate but does not fly up in a high maximum flying height, thereby having a reduced number of shots into the OB area on a driver shot. The present disclosure provides a golf ball comprising a spherical core, an intermediate layer and an outermost cover, wherein a material hardness Hm (Shore D hardness) of the intermediate layer, a material hardness Hc (Shore D hardness) of the outermost cover, a thickness Tc (mm) of the outermost cover, and a total lower volume Vi (mm.sup.3) of a plurality of dimples satisfy Vi>365 and (Hc/Tc)(Hm/Vi)7.5.

Multi-layered golf balls containing a two layered cover assembly are provided. In one embodiment, the cover assembly includes a relatively soft inner cover and relatively hard outer cover. Preferably, at least one of the cover layers is formed from a thermoplastic composition that preferably comprises: a) thermoplastic non-acid polymer, and b) plasticizer. A fatty acid ester such as ethyl oleate is preferably used as the plasticizer. Suitable non-acid polymers include, for example, polyesters, polyamides, polyolefins, and polyurethanes. The cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

A golf ball comprising an inner core layer including a thermoplastic material and having a geometric center hardness less than the surface hardness to define a positive hardness gradient. An outer core layer is formed over the inner core. The outer core includes a thermoset rubber composition and has an inner surface hardness less than an outer surface hardness to define a positive hardness gradient. A cover layer is formed over the outer core layer. The cover layer includes an inner cover layer and an outer cover layer. The thermoplastic material of the core includes an acid copolymer of ethylene and an ,-unsaturated carboxylic acid, optionally a softening monomer comprising alkyl acrylate or methacrylate; a plasticizer; an organic acid or salt thereof; and a cation source present in an amount sufficient to neutralize from about 70 to about 100% of all acid groups present in the material.

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.

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.

A golf ball has a large number of dimples 10 on a surface thereof. The dimples 10 include a plurality of small dimples 10S each having an area of less than 8.0 mm.sup.2, and a plurality of large dimples 10L each having an area of equal to or greater than 8.0 mm.sup.2. A ratio PS of a sum of areas of all the small dimples 10S to a surface area of a phantom sphere of the golf ball is less than 2.0%. A ratio PL of a sum of areas of all the large dimples 10L to the surface area of the phantom sphere is equal to or greater than 79.0%. A degree G of uniformity of areas of the large dimples 10L is equal to or less than 1.15.

A golf ball comprising an inner core layer including a thermoplastic material and having a geometric center hardness less than the surface hardness to define a positive hardness gradient. An outer core layer is formed over the inner core. The outer core includes a thermoset rubber composition and has an inner surface hardness less than an outer surface hardness to define a positive hardness gradient. A cover layer is formed over the outer core layer. The cover layer includes an inner cover layer and an outer cover layer. The thermoplastic material of the core includes an acid copolymer of ethylene and an ,-unsaturated carboxylic acid, optionally a softening monomer comprising alkyl acrylate or methacrylate; a plasticizer; an organic acid or salt thereof; and a cation source present in an amount sufficient to neutralize from about 70 to about 100% of all acid groups present in the material.

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.