A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is molded in a mold having support pins by injection molding. A ratio (K/S) of a surface hardness K of the core 4 to an amount of compressive deformation S of the core 4 satisfies the following mathematical formula.

13.0K/S24.0

The cover 6 has a hardness H of not greater than 62. A product (*V) of a latitude of each support pin and a volume V of the cover 6 is not less than 300.

Multi-piece golf balls containing a multi-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, an intermediate core layer, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. In one preferred embodiment, each core layer has a positive hardness gradient. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof. The intermediate core layer is preferably formed from a first thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a second thermoset composition. The resulting ball has high resiliency and good spin control.

In order to satisfy at a high level the golf ball flight and control performances relied on by professional golfers and skilled amateurs, this invention provides a multi-piece solid golf ball G having a core 1, a cover 3 and an intermediate layer 2 therebetween wherein, letting Hc be the JIS-C hardness at a center of the core, H12 be the JIS-C hardness at a position 12 mm from the core center and Ho be the JIS-C hardness at a surface of the core, the core has a hardness profile which satisfies the condition (HoH12)(H12Hc)10; letting (HoH12)(H12Hc) above be A, the spin index of the ball, defined as the dynamic coefficient of friction of the ball multiplied by A, is at least 3.0; and the hardness profile index, defined as the deflection (mm) of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) multiplied by A, is at least 40.

Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. In one embodiment, the outer cover layer is formed from a composition comprising a thermoplastic polyurethane and epoxy compound. Mixtures of multi-functional amines and imines, and multi-functional isocyanates, and epoxy curing agents; and solvent, can be applied to the outer cover. The resulting coating may contain polyurethanes, polyureas, and hybrids, copolymers, and blends thereof. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)-light stabilizers, and other additives. The coating methods have many benefits and the finished balls have good physical properties.

Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. In one embodiment, the outer cover layer is formed from a composition comprising a thermoplastic polyurethane and epoxy compound. In another embodiment, the cover composition comprises a reaction product of thermoplastic polyurethane, epoxy-functional compound, and epoxy curing agent. Surface coatings of isocyanates, amines, and imines also can be applied to the cover. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)-light stabilizers, and other additives.

Golf ball having CoR of at least 0.700 and compression of at least 50 and comprising a layer of a mixture of thermoset or thermoplastic composition and a plurality of conductive nanoshelled structures such as conductive hollow nanoshells and/or nanorice particles. Conductive nanoshelled structures may be included in amount of from about 2 wt % to greater than 50 wt. % of total weight of mixture. Diameter of each conductive nano shelled structure at widest cross-section may be up to 1000 nm. Each conductive hollow nanoshell may have shell thickness to longitudinal diameter ratio of from about 1:3 to about 1:100. Each nanorice particle may have longitudinal diameter of up to 1000 nm. Shell thickness can be from 1 nm to 100 nm and may be controlled. A layer consisting of mixture may have specific gravity that differs from specific gravity of a layer consisting of the thermoset or thermoplastic composition portion of mixture.

Multi-piece golf balls containing a multi-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, an intermediate core layer, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. In one preferred embodiment, each core layer has a positive hardness gradient. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof. The intermediate core layer is preferably formed from a first thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a second thermoset composition. The resulting ball has high resiliency and good spin control.

A golf ball with a center core comprising polybutadiene and a clay material in an amount ranging from 0.4 to 2.5 weight percent of the center core is disclosed herein. Alternatively, the golf ball has a mantle layer with a blend of ionomer materials and a clay material in an amount ranging from 0.4 to 2.5 weight percent of the mantle layer.

A golf ball 2 includes a core 4, an inner cover 6, a main cover 8, and an outer cover 10. S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core 4, a Shore C hardness Hs at a surface of the core 4, a thickness Tm of the main cover 8, a Shore C hardness Hm of the main cover 8, a thickness Ti of the inner cover 6, a Shore C hardness Hi of the inner cover 6, a thickness To of the outer cover 10 and a Shore C hardness Ho of the outer cover 10, satisfy 15MS100, 0.25<Q/M0.5, and 30<IO.

A golf ball (2) includes a core (4), an inner cover (6), a main cover (8), and an outer cover (10). X=HcRc0.05, S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core (4), a Shore C hardness Hc at a central point of the core (4), a Shore C hardness Hs at a surface of the core (4), a thickness Tm of the main cover (8), a Shore C hardness Hm of the main cover (8), a thickness Ti of the inner cover (6), a Shore C hardness Hi of the inner cover (6), a thickness To of the outer cover (10) and a Shore C hardness Ho of the outer cover (10), satisfy 15MS100, 0.25<Q/M<0.5, 10IO30, and Q/X<0.8.