Compositions including a hardness agent and a water releasing agent and golf ball cores made from such compositions having a tailored hardness gradient are disclosed. The type and concentration of the components in the composition, including a hardness agent and a water releasing agent, affect the hardness, hardness gradient, and compression of cores made from the composition and, thus, can be used to produce a golf ball having desirable performance characteristics.

In a golf ball having a core of at least one layer and a cover of at least one layer encasing the core, at least one layer of the cover is formed of a resin composition which includes (I) a polyurethane or a polyurea, (II) a thermoplastic polyester elastomer and (III) an aromatic vinyl elastomer. The thermoplastic polyester elastomer serving as component (II) and the aromatic vinyl elastomer serving component (III) have specific respective contents and properties, including Shore D hardnesses and rebound resiliences. The golf ball has an excellent controllability on approach shots without a loss of distance on driver shots. In addition, the scuff resistance and moldability are good.

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

Golf ball comprising cast layer of thermoset polymer mixture having centering time Ct.sub.1 and comprising: (i) a polyurethane composition, polyurea composition, and/or polyurethane/polyurea hybrid composition; and (ii) a treated fumed silica compound in an amount such that centering time Ct.sub.1 is independent of the thermoset polymer mixture's degree of cure and lower than a centering time Ct.sub.2 of the thermoset polymer composition (which is dependent on its gel window G.sub.w). The treated fumed silica compound may be surface treated with at least one of polydimethylsiloxane, hexamethyldisilazane, and dimethyldichlorosilane. In some embodiments, delta time t.sub.1 between a dispensing time D.sub.t1 of the thermoset polymer mixture and centering time Ct.sub.1 is less than a delta time t.sub.2 between Ct.sub.1 and centering time Ct.sub.2. Centering time Ct.sub.1 and dispensing time D.sub.a may differ by less than 10 seconds or even by 5 seconds or less.

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

A golf ball includes a core having an outer surface and a geometric center. The core is formed from a substantially homogenous rubber composition. An ionomeric inner cover layer is formed about the core and has a material hardness of about 60 Shore D or greater. The golf ball includes an outer cover layer formed from a polyurea or a polyurethane and having a material hardness of about 60 Shore D or less. The outer surface of the core has a trans content of about 12% or less and a hardness of about 71 to 88 Shore C. The geometric center of the core has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C. The core has an outer surface hardness greater than a geometric center hardness by about 5 to 19 Shore C to define a positive hardness gradient.

Golf ball comprising cast layer of thermoset polymer mixture having centering time Ct.sub.1 and consisting of: (i) a thermoset polymer composition consisting of polyurethane composition, polyurea composition, and/or polyurethane/polyurea hybrid composition; and (ii) a treated fumed silica compound in an amount such that centering time Ct.sub.1 is independent of the thermoset polymer mixture's degree of cure and lower than a centering time Ct.sub.2 of the thermoset polymer composition (which is dependent on its gel window G.sub.w). The treated fumed silica compound may be surface treated with at least one of polydimethylsiloxane, hexamethyldisilazane, and dimethyldichlorosilane. In some embodiments, delta time t.sub.1 between a dispensing time D.sub.t1 of the thermoset polymer mixture and centering time Ct.sub.1 is less than a delta time t.sub.2 between Ct.sub.1 and centering time Ct.sub.2. Centering time Ct.sub.1 and dispensing time D.sub.t1 may differ by less than 10 seconds or even by 5 seconds or less.

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 thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a thermoplastic composition such as an ethylene acid copolymer. The resulting ball has high resiliency and good spin control.

A resin composition for golf balls is made of (A) polyurethane or polyurea and (B) an acrylic resin or a methacrylic resin, component (B) being included in an amount of from 0.5 to 50 parts by weight per 100 parts by weight of component (A). In a golf ball having a core and a cover of one or more layer encasing the core, at least one cover layer is formed of this resin composition. The resin composition is especially useful as a golf ball cover material because it makes it possible to achieve a higher ball initial velocity on shots with a driver and a lower ball initial velocity on approach shots.

Golf ball comprising one or more layers and/or indicia formed from a fluorescent composition comprising: a base polymer; and a colorant; wherein the colorant is a small-molecule ionic isolation lattice formed from one or more fluorescent dye and one or more cyanostar macrocycles. The one or more fluorescent dyes may include at least one dye selected from xanthenes, oxazines, styryls, cyanines, trianguleniums, or mixtures thereof. The colorant may be a dispersion of the small-molecule ionic isolation lattice in a carrier medium or a powder. In particular embodiments, at least one of the one or more layers is a cover layer and/or a coating layer.