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. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof dispersed in a thermoset polymeric matrix. The intermediate core layer is preferably formed from a first thermoplastic composition such as an ethylene acid copolymer ionomer resin; and the outer core layer is preferably formed from a second thermoplastic composition. The resulting ball has high resiliency and good spin control.

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 includes a core, a mid layer, and a cover. The core includes an inner core, a mid core, and an outer core. The mid layer includes an inner mid layer and an outer mid layer. A hardness H(C) is equal to or greater than a hardness H(B). A hardness H(E) is equal to or greater than a hardness H(D). An angle α is calculated by (Formula 1). An angle β is calculated by (Formula 2). The angle α is 0° or greater. A difference (α−β) is 0° or greater. A hardness Hm2 of the outer mid layer is greater than a hardness Hm1 of the inner mid layer.
α=(180°/π)*atan [{H(D)−H(C)}/Y]  (Formula 1)
β=(180°/π)*atan [{H(F)−H(E)}/Z]  (Formula 2)

Golf ball having at least three layers comprising ionomeric and/or HNP compositions, wherein for each two adjacent layers, a relationship is established between a ratio of the volumes of the two adjacent layers and a ratio of the percent neutralizations of those two layers such that the volumes and % neutralizations of all layers are interrelated and interdependent to produce unique and desirable playing characteristics. In one embodiment, a golf ball of the invention has T layers, wherein T≧3 and each of T layers has a different volume “V” and comprises an ionomeric and/or HNP composition having a different % neutralization “N”; and wherein each of n inner layers of the T layers (n<T) has an adjacent surrounding layer n+1 such that a volume V.sub.n and a % neutralization N.sub.n of each inner layer and a volume V.sub.(n+1) and % neutralization N.sub.(n+1) of each adjacent surrounding layer n+1 satisfy the relationship (V.sub.(n+1)−V.sub.n)/V.sub.(n+1)≦(N.sub.n−N.sub.(n+1))/N.sub.(n+1).

In a multi-piece solid golf ball having a core, an intermediate layer encasing the core and a cover which encases the intermediate layer and has numerous dimples on an outside surface thereof, the intermediate layer is formed of a resin material, the cover is formed of a urethane resin material, the core has a diameter of at least 38.0 mm, the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of at least 3.9 mm, the core has a center and a surface such that the value obtained by subtracting the JIS-C hardness at the core center from the JIS-C hardness at the core surface is at least 15, the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) has a surface hardness on the Shore D hardness scale of at least 69, the ball has a surface hardness on the Shore D hardness scale of 62 or less, and the (intermediate layer thickness)/(core diameter) value is from 0.025 to 0.043, the (cover thickness)/(core diameter) value is from 0.014 to 0.027.

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.

An object of the present invention is to provide a method for obtaining a golf ball having excellent impact durability. The present invention provides a method for producing a golf ball, comprising a first step of kneading (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinkable compound having two or more polymerizable unsaturated bonds in a molecule thereof, and (d) a crosslinking initiator to prepare a core rubber composition; a second step of producing the spherical core from the core rubber composition at a molding temperature in a range from 100° C. to 150° C.; and a third step of molding the at least one cover layer covering the spherical core on the spherical core.

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. 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.

To provide a golf ball that can prevent a decrease in carry distance of a driver shot when it rains and also, can exert excellent spinning performance upon an approach shot. The golf ball of the present invention includes a core, a cover that is provided on an outer side of the core and is provided with dimples, and an outermost layer that is formed on an outer side of the cover and made of a material having a contact angle of 90° or more. The golf ball has a dynamic friction coefficient of 0.52 or more. The material constituting the outermost layer comprises a urethane coating that contains a water repellent additive, and the water repellent additive includes a fluorinated surfactant, silicone-modified acrylate or hydrophobic silica. The urethane coating comprises a polyisocyanate as a curing agent, and the polyisocyanate includes both an adduct form and an isocyanurate form of hexamethylene diisocyanate, and a mixing ratio (isocyanurate form/adduct form) of the isocyanurate and adduct forms of the hexamethylene diisocyanate, expressed as a mass ratio, is from 95/5 to 40/60.