Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided.

Multi-layered golf balls having a dual-layered core and cover of at least one layer are provided. The dual-core construction includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An outer core layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. In one version, the foamed outer core layer is made of a relatively soft foam composition having low flex modulus and density. The foamed outer core layer may specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. A cover may be disposed about the core structure. For example, an inner cover made of ethylene acid copolymer ionomer and outer cover made of polyurethane may be used.

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.

Golf ball incorporating layer(s) of a mixture consisting of: i) ionomer(s); ii) ethylene propylene rubber(s)(EPR(s)); iii) polymeric epoxy crosslinker(s); and iv) compatibilizing polymer(s). The ionomer(s) and EPR(s) may be included in a blend in a wt % ratio of from about 85:15 to 55:45; the at least one polymeric epoxy crosslinker and compatibilizing polymer may be included in amounts, based on 100 parts of the blend, of from about 2.0 to about 10.0 parts; and from about 1.0 to about 10.0 parts, respectively. Each ionomer, EPR, polymeric epoxy crosslinker, and compatibilizing polymer has a density less than 1.0 g/cm.sup.3. The mixture is melt processable/moldable without meanwhile sacrificing target CoR, DCM compression, Shore D hardness, and Shore C hardness.

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

Golf ball comprising layer(s) consisting of a mixture consisting of: i) ethylene acid copolymer(s) and/or ionomer(s); ii) polyethylene(s); iii) polymeric epoxy crosslinker(s); and iv) compatibilizing polymer(s). The ethylene acid copolymer(s)/ionomer(s) and the polyethylene(s) may be included in a blend in a wt % ratio of from about 85:15 to 55:45; the at least one polymeric epoxy crosslinker and compatibilizing polymer may be included in amounts, based on 100 parts of the blend, of from about 2.0 to about 10.0 parts; and from about 1.0 to about 10.0 parts, respectively. The polyethylene may be polyethylene butene; polyethylene hexene; polyethylene octene; and combinations thereof. Each ethylene acid copolymer, polyethylene, polymeric epoxy crosslinker, and compatibilizing polymer has a density less than 1.0 g/cm.sup.3. The mixture is moldable and meanwhile possesses similar desirable CoR, DCM compression, Shore D hardness, and Shore C hardness as a mixture consisting of ingredients i), ii) and iv).

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises at least three layers, including at least one thermoset layer and at least one thermoplastic layer. The innermost core layer is relatively small, having a diameter of from 0.50 inches to 1.30 inches.

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.

In a multi-piece solid golf ball having a core and four successive layers encasing the corean inner envelope layer, an outer envelope layer, an intermediate layer and a cover, the inner envelope, outer envelope and intermediate layer are each formed of different highly neutralized resin materials, and the cover thickness is larger than the respective thicknesses of the inner envelope layer, outer envelope layer and intermediate layer. Also, the value (A)(B) obtained by subtracting the material hardness (B) of the softest layer among the inner envelope layer, outer envelope layer and intermediate layer from the material hardness (A) of the cover is a Shore D hardness of 13 or more. This golf ball holds down the spin rate on full shots with a driver by amateur golfers having modest head speeds, and also has a soft and good feel at impact.

Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided.