Golf ball comprising a positive hardness gradient core and an outer cover layer having a microhardness gradient and being formed from a thermoset polyurethane material throughout, and having: i) a treated region that is contacted with a thermoset polyurethane microhardness-increasing solution consisting of an isocyanate portion and at least one non-aqueous solvent; and ii) an untreated region that is not contacted with the thermoset polyurethane microhardness-increasing solution. The treated region comprises the isocyanate portion, whereas the untreated region does not comprise the isocyanate portion. Treated region has a microhardness M.sub.1 that is greater than microhardness M.sub.2 of untreated region to define the outer cover layer positive microhardness gradient M=M.sub.1M.sub.2. The treated region may have a depth Dtr that extends inward from the cover outer surface and in some embodiments is less than a thickness of the untreated region. Treated region may alternatively extend from the inner surface toward outer surface.

Use of highly phase separated thermoplastic polyether ester elastomers for injection molded golf ball core layers is disclosed herein. The thermoplastic polyether ester elastomer comprises a polytetramethylene glycol (PTMO), a cycloaliphatic diol, and dimethyl terephthalate.

A golf ball includes a core having an outer surface and a geometric center. The core is formed from a substantially homogenous rubber composition. An ionomeric inner cover layer is formed about the core and has a material hardness of about 60 Shore D or greater. The golf ball includes an outer cover layer formed from a polyurea or a polyurethane and having a material hardness of about 60 Shore D or less. The outer surface of the core has a trans content of about 12% or less and a hardness of about 71 to 88 Shore C. The geometric center of the core has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C. The core has an outer surface hardness greater than a geometric center hardness by about 5 to 19 Shore C to define a positive hardness gradient.

Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided.

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.

Golf balls having a multi-layered solid core and multi-layered cover are provided. The center of the core is made of a thermoset rubber material and preferably has a positive hardness gradient. The intermediate core layer is made of a thermoset or thermoplastic composition. The outer core layer is made of a highly neutralized polymer composition. The inner cover is made of a thermoplastic composition, preferably an ethylene acid copolymer. The thermoplastic ethylene acid copolymer ionomer can have acid groups that are partially or highly neutralized. The outer cover is made of a composition comprising a polyurethane, polyurea, or copolymer or blend thereof. The finished ball has high resiliency and rebounding properties.

The present invention comprises a method for forming a golf ball comprising synthesizing an acid copolymer using controlled radical polymerization, mixing the acid copolymer with a monomer containing a carbon-carbon double bond, creating a mixture and neutralizing the mixture with a metallic base, forming an ionomeric thermoplastic elastomer for use in a cover layer for a golf ball.

The present invention relates to the use of a mono (meth)acrylate ester in a golf ball layer. The mono (meth)acrylate ester may be added to one or more portions of a golf ball including a core, intermediate, or cover layer. For example, in one embodiment, the mono (meth)acrylate ester may be blended with a polybutadiene rubber material. In another embodiment, the mono (meth)acrylate ester of the present invention may be blended with an ionomer. In some embodiments, the mono (meth)acrylate ester may be blended with a formulation including both a polybutadiene rubber component and an ionomer.

Compositions including a hardness agent and a water releasing agent and golf ball cores made from such compositions having a tailored hardness gradient are disclosed. The type and concentration of the components in the composition, including a hardness agent and a water releasing agent, affect the hardness, hardness gradient, and compression of cores made from the composition and, thus, can be used to produce a golf ball having desirable performance characteristics.

Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided. In one version, a six-piece ball having a three-layered core and three-layered cover is formed. Preferably, the inner core is made of a thermoset rubber composition, the intermediate core layer is made of a thermoplastic composition, and the outer core layer is made of a highly neutralized polymer (HNP) composition. The cover includes inner, intermediate, and outer cover layers, wherein the outer cover is made of a composition comprising a polyurethane, polyurea, or copolymer or blend thereof. In a second version, a five-piece ball having a two-layered core and three-layered cover is produced. The finished balls have high resiliency and rebounding properties.