Multi-layered golf balls having at least one layer made from silicone (polysiloxane) elastomers; silicone (polysiloxane) elastomer/polyurethane blends; polycarbonate-polysiloxane blends and copolymers; and polycarbonate-polysiloxane/polyurethane blends are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The polysiloxane compositions have good thermal stability and durability without sacrificing resiliency. The polysiloxane compositions also 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.

Multi-layered golf balls containing a three-layered cover assembly are provided. For example, a cover assembly having an inner cover, intermediate cover, and outer cover layer may be prepared. At least one of the cover layers is formed from a thermoplastic composition that preferably comprises: a) thermoplastic non-acid polymer, and b) plasticizer. A fatty acid ester such as ethyl oleate is preferably used as the plasticizer. Suitable non-acid polymers include, for example, polyesters, polyamides, polyolefins, and polyurethanes. The cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

Multi-layered golf ball core sub-assemblies and the resulting golf balls are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The intermediate and outer core layers are preferably formed from foamed and non-foamed thermoset compositions. For example, the intermediate core can be formed from a thermoset rubber so there are adjoining foam core layers (inner and intermediate) and the outer core layer can be formed from a non-foamed thermoset rubber. The core layers have different hardness and specific gravity levels. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency.

An object of the present invention is to provide a golf ball having a novel core structure and traveling a great flight distance on driver shots. The present invention provides a golf ball comprising a core composed of a spherical center and an envelope layer and at least one cover layer disposed outside the core, wherein the spherical center has an internal hardness difference between a maximum hardness and a minimum hardness of less than 5 in JIS-C hardness, the envelope layer is formed from an envelope 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) an crosslinking initiator and (d) an acid and/or a salt thereof, and the outermost cover layer has a highest hardness among the constituent members of the golf ball.

A golf ball comprising an inner core layer including a thermoplastic material and having a geometric center hardness less than the surface hardness to define a positive hardness gradient. An outer core layer is formed over the inner core. The outer core includes a thermoset rubber composition and has an inner surface hardness less than an outer surface hardness to define a positive hardness gradient. A cover layer is formed over the outer core layer. The cover layer includes an inner cover layer and an outer cover layer. The thermoplastic material of the core includes an acid copolymer of ethylene and an ,-unsaturated carboxylic acid, optionally a softening monomer comprising alkyl acrylate or methacrylate; a plasticizer; an organic acid or salt thereof; and a cation source present in an amount sufficient to neutralize from about 70 to about 100% of all acid groups present in the material.

Multi-layer golf balls having a hard, high compression center, a relatively soft intermediate layer, and a stiff outer cover layer, are provided. The outer surface hardness of the intermediate layer is less than that of both the center and the outer cover layer.

Golf balls having an inner core made of a foamed composition are provided. The core assembly preferably includes a foam inner core (center) and surrounding outer core layer. A cross-linked thermoplastic, preferably an ethylene acid copolymer ionomer, is used to form the foam composition. The core layers have different hardness gradients and specific gravity values. The ethylene acid copolymer is reacted with a metallic acrylate salt and peroxide free-radical initiator to form the cross-linked polymer. The foamed, cross-linked composition helps provide the inner core with good resiliency, thermal stability, and durability. Non-foamed thermoplastics or thermosets such as polybutadiene rubber may be used to form the outer core layer. The ball further includes a cover that may be multi-layered.

Multi-layered golf balls containing a three-layered cover assembly are provided. For example, a cover assembly having an inner cover, intermediate cover, and outer cover layer may be prepared. At least one of the cover layers is formed from a thermoplastic composition that preferably comprises: a) thermoplastic non-acid polymer, and b) plasticizer. A fatty acid ester such as ethyl oleate is preferably used as the plasticizer. Suitable non-acid polymers include, for example, polyesters, polyamides, polyolefins, and polyurethanes. The cover assembly has good impact durability and helps provide the ball with relatively high resiliency at given compressions.

A golf ball includes a core, one or more mid layers, a cover, and dimples. A central hardness Ho and a surface hardness Hs of the core, a hardness Hm(min) of a layer having a lowest hardness among the mid layers, and a hardness Hc of the cover satisfy the following mathematical formulas (i) to (iv).

HsHo>15(i)

HcHm(min)>20(ii)

10<Hm(min)Ho<15(iii)

5<HcHs<20(iv)

Disclosed herein are multilayer golf balls having a layer with a higher Shore C hardness and a lower Shore D hardness than another layer.