In a golf ball for professional golfers and skilled amateurs which has a single-layer core, a cover and at least one intermediate layer therebetween, the intermediate layer has a specific gravity of at least 1.05, the sphere the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) and the ball have a surface hardness relationship which satisfies the condition:

(surface hardness of intermediate layer-encased sphere)>(surface hardness of ball).

The core has a diameter of from 35.5 to 39.5 mm and a distinctive hardness profile that satisfies specific conditions. The ball is endowed with both an excellent flight performance and excellent durability to repeated impact.

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 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.

The present invention provides methods for producing molded golf balls and the resultant balls. The methods of this invention involve producing foamed polyurethane covers and these methods help reduce dimple distortions and other surface imperfections. These golf balls contain an inner core and outer foamed polyurethane cover. One or more intermediate layers can be disposed between the core and cover. In one embodiment, a castable liquid polyurethane composition containing a foaming agent is dispensed into mold cavities, which are then pressed together to form a foam cover for the ball.

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.

An object of the present invention is to provide a golf ball showing a small ratio of a spin rate on driver shots to a spin rate on approach shots. The present invention provides a multi-piece golf ball comprising a spherical center, three or more envelope layers covering the spherical center, and a cover covering the envelope layers, wherein adjacent two envelope layers are formed so as to include a region composed of elements having a hitting deformation ratio of 30% or more, the hitting deformation ratio being obtained by analyzing a specified golf ball model by a finite element method; and the envelope layer which is radially outwardly positioned of the adjacent two envelope layers has a lowest hardness among all the envelope layers.

Golf ball having CoR of at least 0.700 and Atti compression of at least about 50 and comprising layer consisting of mixture of thermoset or thermoplastic composition and plurality of particulates, at least a portion surface-treated with alkoxylated siloxanes and/or polyether-modified siloxanes, and may be selected from titanium dioxide particles, barium sulfate particles, zinc sulfide particles, and/or zinc oxide particulates. At least some particulates are contacted with compound having the formula: ##STR00001## Compound (I) may be included in amount of 0.01 to 2% by weight based on total weight of portion of plurality being contacted. The plurality may be included in mixture in amount such that layer has specific gravity of from 0.5 to about 10.0, tensile strength of from about 300 psi to about 50,000 psi, and elongation at break of from about 20% to about 1000%, each being greater than that of the thermoset or thermoplastic composition portion of the mixture.

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises at least one intermediate core layer formed from a composite composition comprising functionalized nano-structures. The functionalized nano-structures may be selected from the group consisting of functionalized polymer nano-structures, functionalized metallic nano-structures, and functionalized elemental nano-structures. For example, the functionalized nano-structures may comprise functionalized graphene, functionalized carbon nanotube, and/or functionalized polyamide nano-fiber. The functionalized nano-structures may be mixed/blended or otherwise combined with conductive nanoshelled structures in the composite composition.

Multi-layered, golf balls having a 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 comprising secondary blowing agents that are activated by heat is used to form the foam center. Non-foamed thermoset materials such as polybutadiene rubber may be used to form the outer core layer. The core layers have different hardness gradients and specific gravity values. The foam cores have good resiliency, thermal stability, and durability over a wide temperature range. The ball further includes a cover that may be multi-layered.