In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer, and a cover with a plurality of dimples formed thereon, the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of synthetic resin materials, and the cover layer is formed primarily of a urethane material. The relationships between, respectively, the surface hardnesses of the envelope layer-encased sphere and the ball, the thicknesses of the intermediate layer and the cover layer, the deflections of the core and the ball, and the initial velocities of the core and various layer-encased spheres of the ball each satisfy specific conditions. This golf ball makes it possible for amateur golfers, while maintaining a good distance on shots with a driver (W#1), to obtain a good ball controllability on approach shots and moreover experience a soft feel at impact.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core is formed of one or more layer of a rubber composition; the envelope layer, intermediate layer and cover are each formed of a single layer of resin material; the hardness relationship among the layers satisfies the following two conditions:
material hardness of cover>material hardness of intermediate layer, and
material hardness of envelope layersurface hardness of core;
the ball additionally satisfies the condition: envelope layer thickness (mm)envelope layer material hardness (Shore D hardness) cover thickness (mm)cover material hardness (Shore D hardness); and the core and ball have optimized deflections when subjected to a specific loading. This ball serves as a distance ball which enables a superior distance to be achieved on full shots with a driver and with irons.

In a multi-piece solid golf ball having a rubber two-layer core consisting of an inner layer and an outer layer, a cover, and at least one intermediate layer therebetween, the inner core layer has a diameter of at least 30 mm, the difference in JIS-C hardness between the center of the inner core layer and the surface of the outer core layer is at least 25, the ball satisfies the relationship A/B1.5, where A and B are the deflections of, respectively, the inner core layer and the two-layer core when compressed under specific loading conditions, and the intermediate layer has a higher material hardness than the cover. This ball enables mid- to high-level golfers both to achieve even longer distances and to maintain the spin performance on approach shots at a high level.

A method of forming a golf ball is disclosed herein. The method includes injecting a cover mixture into a mold to form a cover mixture comprising a thermoplastic polyurethane resin and a polyahl, subjecting the golf ball to a polyisocyanated solution to create a golf ball with a polyisocyanated cover, and heating the golf ball or polyisocyanated cover to remove a solvent component of the polyisocyanated solution and promote the reaction of the polyisocyanate with the cover mixture and polyahl.

Disclosed herein are two-layer and three-layer, low compression golf balls including a low compression single- or dual-layer rubber core and a single cover layer.

A golf ball comprising a cover composed of a PPDI-based thermoplastic polyurethane material. The phase morphology of the PPDI-based thermoplastic polyurethane material coupled with high levels of hard segment domain cohesion imparts excellent low temperature flexibility, rubber like elasticity, and mechanical properties to the final elastomer.

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a thermoplastic composition, preferably including: a) ethylene acid copolymer, b) plasticizer, and c) cation source. Preferably, a fatty acid ester such as ethyl oleate is used as the plasticizer. The outer core layer is preferably formed from a thermoset composition such as polybutadiene rubber. The core layers have different hardness levels. For example, the inner core can have a positive, zero, or negative hardness gradient. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency at given compressions.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer, and a cover with a plurality of dimples thereon, the core is a two-layer core consisting of an inner core layer and an outer core layer each formed primarily of a base rubber, the envelope layer, the intermediate layer and the cover layer are each composed of at least one layer and formed primarily of a synthetic resin material, and the initial velocities and surface hardnesses of the core, the envelope layer-encased sphere and the intermediate layer-encased sphere are designed within specific ranges. This golf ball satisfies at a very high level the flight and control performances expected for use by professional golfers and skilled amateurs, has the ability to move forward on a straight path particularly on full shots, and also has an excellent scuff resistance.

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises a layer formed from a highly neutralized polymer composition and a layer formed from a thermoset rubber.

A golf ball comprising at least one layer comprised of a neutralized acid polymer composition consisting of a mixture of: (a) at least one low molecular weight acid-containing wax; (b) at least one non-acid-polymer; and (c) at least one organic acid or salt thereof. Each low molecular weight acid-containing wax may have a molecular weight of from about 500 to about 7000, and in some embodiments, the molecular weight may be considered low up to 30,000. Interactions between components (a), (b) and (c) as disclosed herein advantageously produce a layer of ionomeric material having desirable physical properties, such as heat stability, and processability (excellent melt flow) without the need for blending high and low molecular weight acid-containing polymer(s)