Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises at least three layers, including at least one thermoset layer and at least one thermoplastic layer. The innermost core layer is relatively small, having a diameter of from 0.50 inches to 1.30 inches.

Golf ball having CoR of at least 0.810, specific gravity SG.sub.B of less than 1.00 g/cc, and initial velocity of at least 250 ft/s and comprising a first layer L.sub.1, a second layer L.sub.2 surrounding L.sub.1, and a third layer L.sub.3 surrounding L.sub.2. L.sub.1 is formed from at least one highly neutralized polymer and has first specific gravity SG.sub.1; L.sub.2 is formed from at least one partially neutralized polymer and has second specific gravity SG.sub.2; and L.sub.3 is formed from at least one of a thermoset or thermoplastic composition and has third specific gravity SG.sub.3. At least two of SG.sub.1, SG.sub.2, and SG.sub.3 is less than 1.13 g/cc. SG.sub.1 may be less than 1.13 g/cc, or less than 1.0 g/cc. The thermoset or thermoplastic composition may comprise polyurethane(s), polyurea(s), polyurethane(s)/polyurea(s) hybrids, and/or ionomers such as at least partially neutralized polymers and/or HNPs.

Golf balls having a multi-layered core made of a foamed composition are provided. The core preferably has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. Preferably, a polyurethane foam composition is used to form the foam center. The foam inner core preferably includes a fully-foamed center region and a partially or completely-collapsed foam outer region. The hardness of the fully-foamed region is different than the hardness of the collapsed foam region. Non-foamed thermoset or thermoplastic materials such as polybutadiene rubbers or ethylene acid copolymer ionomer may be used to form the outer core layer. The ball further includes a cover that may be multi-layered. The foam cores have good resiliency.

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

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

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The outer core layer is preferably formed from a non-foamed thermoset composition such as polybutadiene rubber. The core layers have different hardness and specific gravity levels. The specific gravity (density) of the foam inner core is preferably less than the density of the outer core layer. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency.

Multi-piece golf balls having a solid core and cover are provided. The ball contains a small, heavy inner core and surrounding outer core layer. The inner core preferably contains metal powder such as copper, steel, brass, tungsten, titanium, nickel, iron, tin, and bronze particles dispersed in a thermoset or thermoplastic polymeric matrix. For example, a polybutadiene rubber matrix may be used. In one preferred embodiment, the inner core contains elemental iron powder. Preferably, the particles have a weight average size in the range of about 10 m to about 450 m. In one embodiment, the outer surface of the inner core has a structure with projecting members. For example, the outer surface may contain multiple projecting ribs with gaps located between the ribs. The ball includes a cover surrounding the core structure. The cover may be multi-layered.

In a multi-piece solid golf ball having a core, a cover and an intermediate layer therebetween, the core, an intermediate layer-encased sphere and the ball have surface hardnesses which satisfy a specific relationship, and the intermediate layer and the cover have thicknesses which satisfy a specific relationship. Also, the core has a hardness profile in which the hardnesses at the core surface, core center, a position 5 mm from the core center, and a position midway between the surface and center of the core satisfy specific relationships. This golf ball, when used by mid- and high-level amateurs, enables the golfer to maintain an adequate distance on shots with a driver and achieve a good distance on iron shots, has a good spin performance on approach shots and has a good feel on impact. In addition, the ball has an excellent scuff resistance when struck with a grooved wedge.

A golf ball includes a main body and a paint layer positioned outside the main body. The paint layer includes an inner layer and an outer layer positioned outside the inner layer. When an indentation depth (nm) is measured on a cross-section along a plane passing through a central point of the golf ball when a force of 30 mgf is applied to the cross-section in a direction perpendicular to the cross-section, an indentation depth Di on a cross-section of the inner layer is smaller than an indentation depth Do on a cross-section of the outer layer. A thickness To of the outer layer is larger than a thickness Ti of the inner layer.

Multi-layered golf balls having at least one layer made of a polyamide composition containing a plasticized polyamide are provided. In one preferred version, the polyamide composition consists essentially of a polyamide and plasticizer selected from the group consisting of polytrimethylene ether glycol and polytrimethylene ether glycol benzoate and monomers, oligomers, copolymers and blends thereof. Blends of plasticized polyamides and ethylene acid copolymer ionomers also can be prepared. The golf ball includes a core having at least one layer and a cover having at least one layer. The polyamide composition may be used to form any core, cover, or other layer in the golf ball. The polyamide compositions have a good combination of properties including Coefficient of Restitution (COR) and compression.