Golf ball comprising layer(s) comprised of neutralized acid polymer composition consisting of mixture of: (a) low molecular weight acid-containing wax(es); (b) non-acid polymer(s) including at least one low molecular weight non-acid wax such as high density oxidized polyethylene homopolymers; ethylene maleic anhydride copolymers; polypropylene maleic anhydride copolymers; polypropylene homopolymers; ethylene-vinyl acetate copolymers; high density oxidized homopolymers; oxidized copolymers; polyethylene micronized waxes; polytetrafluoroethylene micronized waxes; emulsifiable low molecular weight non-acid waxes; non-emulsifiable low molecular weight non-acid waxes; and/or chemically modified low molecular weight non-acid waxes; and (c) organic acid(s) or salt thereof. Molecular weight of each low molecular weight acid-containing wax is about 500 to 7000, or up to 30,000. Interactions between components (a), (b), and (c) advantageously produce layer of ionomeric material having heat stability, processability, and well-retained durability, adhesion, CoR, compression and targeted feel without need for blending high and low molecular weight acid-containing polymer(s).

A golf ball 2 includes a core 4, an inner cover 6, a main cover 8, and an outer cover 10. S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core 4, a Shore C hardness Hs at a surface of the core 4, a thickness Tm of the main cover 8, a Shore C hardness Hm of the main cover 8, a thickness Ti of the inner cover 6, a Shore C hardness Hi of the inner cover 6, a thickness To of the outer cover 10 and a Shore C hardness Ho of the outer cover 10, satisfy 15MS100, 0.25<Q/M0.5, and 30<IO.

Low compression, multi-piece golf balls containing a solid core and two or three-layered cover assemblies are provided. Preferably, the ball has a compression of less than 60 and more preferably less than 50. At least one cover layer is made of a plasticized thermoplastic composition. For example, two-layered and three-layered covers may be made. Preferably, the plasticized thermoplastic composition comprises: a) ethylene acid copolymer, b) plasticizer, and c) cation source. A fatty acid ester such as ethyl oleate or butyl oleate is preferably used as the plasticizer. The cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

A golf ball (2) includes a core (4), an inner cover (6), a main cover (8), and an outer cover (10). X=HcRc0.05, S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core (4), a Shore C hardness Hc at a central point of the core (4), a Shore C hardness Hs at a surface of the core (4), a thickness Tm of the main cover (8), a Shore C hardness Hm of the main cover (8), a thickness Ti of the inner cover (6), a Shore C hardness Hi of the inner cover (6), a thickness To of the outer cover (10) and a Shore C hardness Ho of the outer cover (10), satisfy 15MS100, 0.25<Q/M<0.5, 10IO30, and Q/X<0.8.

A golf ball (2) includes a core (4), an inner cover (6), a main cover (8), and an outer cover (10). X=HcRc0.05, S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core (4), a Shore C hardness Hc at a central point of the core (4), a Shore C hardness Hs at a surface of the core (4), a thickness Tm of the main cover (8), a Shore C hardness Hm of the main cover (8), a thickness Ti of the inner cover (6), a Shore C hardness Hi of the inner cover (6), a thickness To of the outer cover (10) and a Shore C hardness Ho of the outer cover (10), satisfy 15MS100, 0.25<Q/M<0.5, 10IO30, and Q/X0.8.

The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, the core being formed of a material molded under heat from a rubber composition which includes (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate. The product PE of the difference P (mol/m.sup.3) in crosslink density between the core surface and the core center, as measured based on a toluene swelling test, multiplied by the deflection E (mm) of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) is at least 2810.sup.2 mol/m.sup.3.Math.mm.

Golf balls and golf ball components made using three-dimensional (3D) additive manufacturing systems are provided. The golf ball includes at least one three-dimensional piece. Preferably, a continuous liquid interface printing method is used to make the three-dimensional structure. Ultraviolet (UV)-light polymerizable materials are used in the method. The method may be used to make single-piece or multi-piece balls. For example, the ball may include an inner core produced by the liquid interface printing method. An outer core layer may be disposed about the inner core, and a cover comprising inner and outer cover layers may encapsulate the core assembly to form the finished golf ball. The outer core and cover layers may be made using conventional molding technologies or the methods of this invention.

Multi-piece golf balls containing a dual-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 having a relatively low specific gravity. The core structure may have different hardness gradients. In one preferred embodiment, the inner core and outer core each 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 outer core layer preferably is formed from a thermoset composition such as polybutadiene rubber. The resulting ball has high resiliency and good spin control.

Multi-layered golf balls containing a two or three-layered cover assembly are provided. In one embodiment, the cover assembly includes a relatively hard inner cover and relatively soft outer cover. Alternatively, the cover assembly may include a relatively soft inner cover with a relatively hard outer cover. Three-layered covers comprising an inner cover, intermediate cover, and outer cover layer also may be prepared. Preferably, at least one of the layers is formed from a thermoplastic composition that comprises: a) ethylene acid copolymer, b) plasticizer, and c) cation source. A sulfonamide, alkyl diacid ester, or organophosphate or organosulfur compound is preferably used as the plasticizer. The cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

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 viscoelastic polyurethane foam composition is used to form the inner core. The foam composition has shape-memory properties. The core has good durability and thermal stability. In other instances, the viscoelastic polyurethane foam composition can be used to make the outer core layer. The core layers can have different hardness gradients and specific gravity values. The ball further includes a cover that can be multi-layered.