A golf ball comprising a core composed of a fully neutralized polymer material is disclosed herein. The golf ball also preferably has multiple mantle layers and a cover.

A golf ball comprising: (a) a core; (b) at least one mantle layer adjacent to the core; (c) an inner cover layer adjacent to the mantle layer; and (d) an outer cover layer adjacent to the inner cover layer, wherein the inner cover layer has a material Shore D hardness that is at least 3 less than the material Shore D hardness of the outer cover layer, and the inner cover layer has a thickness of less than 0.050 in.

An object of the present invention is to provide a golf ball having excellent durability and good shot feeling. The present invention provides a golf ball comprising a core, wherein a difference (crosslinking density at surface of core−crosslinking density at center of core) between a crosslinking density at a surface of the core and a crosslinking density at a center of the core is more than 1.0×10.sup.2 mol/m.sup.3 and less than 9.0×10.sup.2 mol/m.sup.3, and a hardness difference (Hs−Ho) between Hs and Ho is 13.0 or more and 30.0 or less, and the core satisfies H50−Ho>Hs−H50, wherein Hs (Shore C hardness) is a hardness at the surface of the core, Ho (Shore C hardness) is a hardness at the center of the core, and H50 (Shore C hardness) is a hardness at a midpoint between the center of the core and the surface of the core.

In a golf ball having a core, an intermediate layer and a cover, the core is formed primarily of a base rubber, has a diameter set in a specific range and has a specially designed internal hardness profile, the intermediate layer and the cover are each formed of resin materials, and the surface hardness of the ball is higher than the surface hardness of the intermediate layer-encased sphere. This ball achieves a satisfactory distance on full shots with a driver and with long and middle irons, provides a good spin performance on approach shots, and has a durability to repeated impact and a scuff resistance that are both excellent.

In a golf ball having a core composed of one or more layer, the outermost layer of the core is formed of a rubber composition containing a base rubber and an α,β-unsaturated metal carboxylate, an envelope layer directly encasing the core is formed of a resin composition containing a thermoplastic resin having a structure that includes α,β-ethylenically unsaturated carboxylic acid copolymerization units, and a surface of the core outermost layer and the envelope layer adjoin each other through an intervening oxazoline group-containing substance. The golf ball has improved adhesion between the rubber-based core and the cover layer that directly encases the core and is formed of an ionomer resin or other α,β-ethylenically unsaturated carboxylic acid copolymer-containing resin material.

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.

A golf ball with a core comprising polybutadiene and graphene is disclosed herein. The golf ball has a single core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an inner core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an outer core comprising polybutadiene and graphene.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core is formed primarily of a base rubber and has a diameter set in a specific range, the envelope layer, intermediate layer and cover are each formed of resin materials, and the envelope layer is formed into two layers—an inner layer and an outer layer. The center and surface hardnesses of the core, the surface hardness of the inner envelope layer-encased sphere, the surface hardness of the outer envelope layer-encased sphere, the surface hardness of the intermediate layer-encased sphere and the surface hardness of the ball together satisfy a specific relationship. This ball achieves a satisfactory distance on full shots both with a driver and with irons, in addition to which it is superior in the short game and has a good feel at impact and an excellent scuff resistance.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the envelope layer is formed into two layers—an inner envelope layer and an outer envelope layer. The inner envelope layer-encased sphere, outer envelope layer-encased sphere, intermediate layer-encased sphere and ball have respective surface hardness that satisfy a specific relationship. The inner envelope layer or outer envelope layer is formed primarily of one or more elastomer, and further the core has a particular hardness profile. This ball has an excellent flight when struck by golfers whose head speeds are not that fast and has a good, soft feel at impact, thus making it highly suitable for amateur golfers,

Multi-piece golf balls having a solid core made of a foamed composition and a cover are provided. Preferably, the core is dual-layered having has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. Preferably, a polyurethane foam composition containing mineral filler particulate, for example, nanoclay particles, is used to form the foam center. The concentration of clay particulate is preferably in a range of 0.1 to 60% by weight. The surrounding outer core layer may be made from non-foamed or foamed compositions. For example, polybutadiene rubber or highly neutralized olefin acid copolymers may be used in the outer core layer. The core layers have different hardness gradients and specific gravity values.