Multi-layered 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 core layers have different hardness and specific gravity levels. The specific gravity (density) of the foam inner core is preferably less than the density of the outer core layer. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency.

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-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. The core also includes a structural insert such as, for example, a solid shell, perforated shell, a lattice or mesh, or a central hub with extending arms, and the like. The core layers have different hardness gradients and specific gravity values. The ball further includes a cover having at least one layer. By adjusting the respective specific gravity values of the core layers, the Moment of Inertia (MOI) of the ball can be increased or decreased. In one embodiment, the ball has generally good flight distance and low spin rate.

Multi-layered, golf balls having a core made of a particle-based polyurethane foam composition are provided. The ball includes a dual-layered core having a foam inner core (center) and surrounding outer core layer. The surrounding outer core layer is preferably made from a foamed composition. In one embodiment, pre-expanded thermoplastic polyurethane foam beads containing a blowing agent are used to form the foam center and outer core. In another embodiment, pre-formed polyurethane foam particles are used in both core layers. 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.

A golf ball comprising a core and a cover layer, wherein at least one of the core or cover layer comprises a plasticized polyurethane composition comprising at least one polyurethane and at least one plasticizer.

Golf balls having a multi-layered core made of a foamed composition are provided. The core assembly preferably includes a foam inner core (center) and surrounding outer core layer. Preferably, a polyurethane foam composition is used to form the foam center. The core layers have different hardness gradients and specific gravity values. The foamed inner core assembly includes a geometric center, outer surface (skin), and thermal barrier layer that helps protect the foamed center region from the negative effects of high temperatures used during the ball-manufacturing process. Non-foamed thermoset materials such as polybutadiene rubber may be used to form the thermal barrier layer. 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.

A golf ball includes a plurality of dimples on the surface thereof and satisfies the following expression (1):
PS.sub.7/S/H1006.25 (mm.sup.1)(1),
wherein H is a deformation amount, which is expressed by a compressive deformation amount of the golf ball; S is a virtual plane area, which is a surface area of the golf ball determined supposing that no dimple exists on the surface of the golf ball; and PS.sub.7 is a pressurized area, which is an area of the golf ball contacting a plane when a load of 6864 N is applied to the golf ball. The bottom of the dimple includes a center protruding portion with a curved shape protruding toward an outside of the golf ball.

To provide a golf ball that can prevent considerable decrease in carry distance of a driver shot when it rains and also can more reliably prevent adhesion of dirt, etc. to the surface of the golf ball. The golf ball of the present invention includes a core, a cover that is provided on an outer side of the core and has 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 and a dynamic contact angle of 85 or less. The golf ball may have a dynamic friction coefficient of 0.48 or less. The cover may be formed of a material having hardness of 48 or more in terms of Shore D Hardness. The outermost layer may be formed of a urethane coating containing a water repellent additive, as a main component.

A resin composition for golf balls includes specific amounts of (A) polyurethane or polyurea and (B) an oxazoline group-containing acrylic polymer or an oxazoline group-containing styrene polymer. A golf ball having a core encased by a cover of one or more layers, wherein at least one cover layer is formed of this resin composition, exhibits a good adhesion between adjoining layers, enabling the ball to achieve a high scuff resistance without lowering the initial velocity of the ball.

Golf balls having a core, intermediate layer, and shape memory polymer cover are provided. The ball includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. A cover having at least one layer is disposed about the core and intermediate layer. An SMP is used in the outermost layer of a golf ball. SMPs may be used in any layers of the golf ball to achieve reversible deformability.