A golf ball includes a single core having an outer surface and a geometric center. The core is formed from a substantially homogenous rubber composition. An inner cover layer is disposed about the core, the inner cover including a high-acid ionomer and having a material hardness of about 66 to 75 Shore D. The high-acid ionomer has an acid content of about 16% or greater. An outer cover layer is disposed about the inner cover layer, the outer cover including a polyurethane and having a material hardness of about 38 Shore D to about 56 Shore D. The core surface hardness is from 0 Shore C to 15 Shore C lower than the geometric center hardness to define a hardness gradient.

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 P×E 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 28×10.sup.2 mol/m.sup.3.Math.mm.

Low compression multi-piece golf balls having a solid core comprising at least one layer made of a plasticized thermoplastic composition are provided. Preferably, the ball has a compression of less than 60 and more preferably less than 50. The ball includes a cover in addition to the core sub-assembly. For example, two-piece and three-piece golf balls may be made. The plasticized thermoplastic composition preferably comprises: a) ethylene acid copolymer, b) plasticizer, and c) cation source. Preferably, a fatty acid ester such as butyl oleate is used as the plasticizer. In two-layered core constructions, the outer core layer is preferably formed from a thermoset composition such as polybutadiene rubber. The core layers may have different hardness levels. The core structure and resulting ball have relatively good resiliency at given compressions.

A golf ball material includes (A) one or more resin ingredient selected from the group consisting of olefin-unsaturated carboxylic acid random copolymers, olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymers, and metal ion neutralization products of these copolymers; (D) an amino compound having at least 2 amino groups per molecule; (B) one or more resin ingredient selected from the group consisting of polyethylene, polyesters and polyamide elastomers; and (C) an agent for compatibilizing components (A) and (B). The compatibilizing agent (C) includes: (C-i) two different types of base polymer selected from a specific group, (C-ii) a hydrogenated diene polymer having at least one type of functional moiety selected from a specific group of moieties, and (C-iii) an olefinic polymer having at least one type of functional moiety selected from a specific group of moieties.

The presently disclosed subject matter is directed to a golf ball providing improve play characteristics. The disclosed golf ball includes an outer cover comprising a plurality of divots. The disclosed golf ball further includes a central core comprising one or more lightweight materials, such as aerogel. The combination of the lightweight core and the unique divots enable the golf ball to go farther and straighter when hit by the golfer, thereby providing increased performance.

Multi-layered golf balls having at least one layer made of a foamed silicone composition are provided. Multi-layered golf balls having at least one layer made of non-foamed silicone elastomer composition also are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The foamed silicones have good thermal stability and durability without sacrificing resiliency. The non-foamed silicone elastomers have high elongation, tensile strength, chemical/fluid-resistance, and weatherability properties. These compositions can be used to form any layer, for example, core, intermediate, or cover, in the golf ball.

A rubber composition for golf balls includes (A) a base rubber, (B) an acrylate ester or methacrylate ester containing an isocyanate group or a blocked isocyanate group, (C) diacrylic acid, dimethacrylic acid or a metal salt thereof, and (D) an organic peroxide. In a golf ball having a core formed of the rubber composition and a cover of one or more layers which encases the core, the rubber composition exhibits a spin rate-lowering effect on shots and can thus improve the flight performance of the ball.

The presently disclosed subject matter is directed to a golf ball providing improve play characteristics. The disclosed golf ball includes an outer cover comprising a plurality of divots. The disclosed golf ball further includes a central core comprising one or more lightweight materials, such as aerogel. The combination of the lightweight core and the unique divots enable the golf ball to go farther and straighter when hit by the golfer, thereby providing increased performance.

A golf ball core, mantle, and/or cover layer(s) of golf ball having a composition comprising functionalized aluminosilicate particles having a particle size of less than 50 μm is disclosed herein. The aluminosilicate microspheres with an average diameter less than 50 μm are functionalized with, but not limited to, polysulfide, vinyl, amino, epoxy, hydroxyl, carboxyl, methacryloyl, hydrocarbon, mercapto and isocyanate.

A constituent member of a golf ball comprising a vulcanized form of a rubber composition includes (a) a base rubber, (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid and/or a metal salt thereof, (c) an organic peroxide, (d) water, (e) an antioxidant which is a benzoimidazole of the following general formula and/or a metal salt thereof, and (g-1) an organosulfur being alkylphenoldisulfide polymers represented by the specific chemical formula or (h) sulfur. When the rubber composition is used in constituent members of a golf ball, especially the core, the golf ball exhibits low spin properties on shots, resulting in an improved flight performance and enabling a good durability to be maintained.