An object of the present invention is to provide a golf ball having excellent shot feeling and durability. The present invention provides a golf ball comprising a constituent member containing a crosslinked rubber component and resin fine particles, wherein the resin fine particles contain a polyrotaxane component having a cyclodextrin, a linear molecule piercing through the cyclic structure of the cyclodextrin, and blocking groups located at both terminals of the linear molecule to prevent disassociation of the cyclodextrin, wherein at least a part of hydroxyl groups of the cyclodextrin is modified with a caprolactone chain via a OC.sub.3H.sub.6O group.

Golf ball incorporating polyurethane mixture having wt. % NCO content of 4-20 and including a prepolymer polyol portion comprised of trans--Farnesene diol(s) in an amount of about 3-70 wt. % of total weight of prepolymer. Trans--Farnesene diol may be 15 carbon, long chain, branched, unsaturated 3,4-vinyl-containing bio-hydrocarbon having the formula:

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Prepolymer can include a 1:99 to 99:1 blend (wt. % ratio) of Trans--Farnesene diol(s) and polybutadiene-based polyol(s) in an amount of about 35-85 wt. %, along with about 15 wt. %-65 wt. % of diisocyanate(s). Curative may be combined with prepolymer in amount of about 3-25 wt. % of total weight of curative and prepolymer combined, and may be mixture of aromatic diamine(s) and white dispersion in a wt. % ratio of about 90:10 to 50:50, plus catalyst. Hardness of polyurethane mixture can be from 75 Shore A to 75 Shore D or a material hardness can be from about 40 Shore D to about 65 Shore D.

An object of the present invention is to provide a golf ball having excellent shot feeling on driver shots. The present invention provides a golf ball comprising a core and at least one cover covering the core, wherein the core is formed from a core rubber composition containing (a) a base rubber containing a polybutadiene, (b) an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) a terpene-based resin.

An object of the present invention is to provide a golf ball having excellent shot feeling on driver shots. The present invention provides a golf ball comprising a core and at least one cover covering the core, wherein a material for forming the core has a loss tangent difference tan (tan .sub.80tan .sub.40) of 0.12 or more between a loss tangent tan .sub.80 at 80 C. and a loss tangent tan .sub.40 at 40 C.

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises a center, an intermediate core layer, and an outer core layer. At least one layer of the multi-layer core is a high specific gravity layer.

A multi-piece solid golf ball having a two-layer core with an inner core layer and an outer core layer and having a cover of at least two layers including an intermediate layer and an outer layer with numerous dimples on the surface is characterized in that the hardest cover layer has a specific material hardness and the ball has a specific value obtained by subtracting the surface hardness of the overall core from the surface hardness of the hardest cover layer, a specific deflection, and a specific value obtained by subtracting the initial velocity of the inner core layer from the initial velocity of the sphere consisting of the inner core layer encased by the outer core layer. This golf ball enables relatively low head speed golfers to achieve a good distance on full shots with drivers and iron clubs and also provides a soft, comfortable feel at impact.

A golf ball includes a spherical core, and a cover covering the spherical core. The spherical core is formed from a rubber composition including a base rubber, a co-cross-linking agent, a cross-linking initiator, and an unsaturated fatty acid and/or a metal salt thereof, the co-cross-linking agent includes ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof, the unsaturated fatty acid and/or metal salt thereof excludes an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and a metal salt thereof, an unsaturated aliphatic carboxylic acid that forms the unsaturated fatty acid and/or metal salt thereof has a functional group other than a carboxy group and a carbon-carbon unsaturated bond, and the rubber composition further includes a metal compound when the co-cross-linking agent is only an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms.

A golf ball for amateur golfers is endowed with both an excellent flight and a good feel at impact that is soft and solid when hit by the average golfer whose head speed is not very high. The golf ball, which includes a core and a cover, has a compressive deformation A when subjected to a final load of 5 kg from an initial load of 0.2 kg that is 0.21 mm or less, a compressive deformation B when subjected to a final load of 30 kg from an initial load of 5 kg that is from 0.72 to 0.90 mm and a compressive deformation C when subjected to a final load of 60 kg from an initial load of 5 kg that is from 1.55 to 1.80 mm.

Multi-piece golf balls having a solid core made of a foamed composition and a cover are provided. Preferably, the core is dual-layered having has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. Preferably, a polyurethane foam composition containing mineral filler particulate, for example, nanoclay particles, is used to form the foam center. The concentration of clay particulate is preferably in a range of 0.1 to 60% by weight. The surrounding outer core layer may be made from non-foamed or foamed compositions. For example, polybutadiene rubber or highly neutralized olefin acid copolymers may be used in the outer core layer. The core layers have different hardness gradients and specific gravity values.

Multi-piece golf balls containing a dual-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, 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 preferably dispersed in a thermoplastic polymeric matrix. Different plasticizers such as fatty acid esters may be used. The outer core layer is preferably formed from a thermoset composition such as polybutadiene. The resulting ball has high resiliency and good spin.