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 plasticizer 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.

Golf ball incorporating polymer composition comprising: (i) a reaction mixture of ethylene-acid copolymer and C.sub.3-8 , -ethylenically unsaturated carboxylic acid(s); and (ii) poly-hydroxy crosslinking agent(s) such as polyvinyl alcohol, diols, glycols, sugar alcohols, and/or glycerols. Concentration of poly-hydroxy crosslinking agent(s) in polymer composition may be up to about 10% (or up to about 5%, or from 0.1% to about 2.5%, or from about 0.05% to 0.95%), by weight, based on 100% total weight of polymer composition. Reaction mixture may further comprise cation source and optionally organic acid(s) or salt thereof. Reaction mixture or polymer composition may include adjuvant(s). such as a silane compound, for example N-(2-aminoethyl-3 aminopropyl)trimethoxysilane and/or 3-glycidoxypropyl trimethoxysilane, in concentration of from 0.025% to 1.0% by weight, based on 100% total weight of reaction mixture or in concentration of up to 10% by weight, based on 100% total weight of the polymer composition.

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises a center and an outer core layer that are both soft relative to a hard intermediate core layer. The Shore C hardness of the outer surface of the center is preferably less than the Shore C hardness of the geometric center of the center.

An ultra-low compression golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

A golf ball that includes (a) a core comprising a center; (b) an outer cover layer; and (c) one or more intermediate layers; wherein at least one of the core or the intermediate layer comprises a composition that includes (i) at least one polyalkenamer and at least one ionomer. A method for making a golf ball comprising a core, one or more intermediate layers and an outer cover layer is also disclosed, wherein the method includes forming a blend comprising at least one polyalkenamer rubber and at least one ionomer; and injection molding the blend into a spherical mold to form the intermediate or outer cover layer.

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.

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 composition selected from thermoset compositions and thermoplastic compositions. 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.

An ultra-low compression three-piece golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

An object of the present invention is to provide a golf ball excellent in flying performance, in particular, to provide a golf ball traveling a great flight distance. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (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 (d1) an aromatic carboxylic acid or (d2) an aromatic carboxylic acid salt, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the ,-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

An object of the present invention is to provide a golf ball showing a low spin rate on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (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 carboxylic acid having a heterocyclic ring and/or a salt thereof, provided that the rubber composition further contains (e) a metal compound in case of containing only (b) the ,-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.