Multi-piece golf balls having a solid core made of a foamed silicone composition and a cover are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core structures can be made. Preferably, a dual-core having has a silicone foam inner core (center) and surrounding silicone foam outer core layer is made. The core layers can have different hardness gradients. The silicone foam center and outer core layer have good thermal stability and durability and provide the ball with good resiliency.

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.

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.

Golf ball having at least three layers comprising ionomeric and/or HNP compositions, wherein for each two adjacent layers, a relationship is established between a ratio of the volumes of the two adjacent layers and a ratio of the percent neutralizations of those two layers such that the volumes and % neutralizations of all layers are interrelated and interdependent to produce unique and desirable playing characteristics. In one embodiment, a golf ball of the invention has T layers, wherein T≧3 and each of T layers has a different volume “V” and comprises an ionomeric and/or HNP composition having a different % neutralization “N”. Furthermore, each of n inner layers of the T layers (n<T) has an adjacent surrounding layer n+1 such that a volume V.sub.n and a % neutralization N.sub.n of each inner layer and a volume V.sub.(n+1) and % neutralization N.sub.(n+1) of each adjacent surrounding layer n+1 satisfy the relationship (V.sub.n−V.sub.(n+1))/N.sub.n≧(N.sub.n−N.sub.(n+1))/N.sub.(n+1).

Golf ball having at least three layers comprising an ionomeric and/or HNP composition, wherein for each two adjacent layers, a relationship is established between a ratio of the volumes of the two adjacent layers and a ratio of the percent neutralizations of those two layers such that the volumes and % neutralizations of all layers are interrelated and interdependent to produce unique and desirable playing characteristics. In one embodiment, each of T layers, wherein T≧3, has a different volume “V” and comprises an ionomeric/HNP composition having a different % neutralization “N”; and wherein each of n inner layers of the T layers (n<T) has an adjacent surrounding layer n+1 such that a volume V.sub.n and a % neutralization N.sub.n of each inner layer and a volume V.sub.(n+1) and % neutralization N.sub.(n+1) of each adjacent surrounding layer n+1 satisfy the relationship (V.sub.(n+1)−V.sub.n)/V.sub.(n+1)≦(N.sub.(n+1)−N.sub.n)/N.sub.n.

Golf ball having at least three layers comprising ionomeric and/or HNP compositions, wherein for each two adjacent layers, a relationship is established between a ratio of the volumes of the two adjacent layers and a ratio of the percent neutralizations of those two layers such that the volumes and % neutralizations of all layers are interrelated and interdependent to produce unique and desirable playing characteristics. In one embodiment, a golf ball of the invention has T layers, wherein T≧3 and each of T layers has a different volume “V” and comprises an ionomeric and/or HNP composition having a different % neutralization “N”; and wherein each of n inner layers of the T layers (n<T) has an adjacent surrounding layer n+1 such that a volume V.sub.n and a % neutralization N.sub.n of each inner layer and a volume V.sub.(n+1) and % neutralization N.sub.(n+1) of each adjacent surrounding layer n+1 satisfy the relationship (V.sub.(n+1)−V.sub.n)/V.sub.(n+1)≦(N.sub.n−N.sub.(n+1))/N.sub.(n+1).

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises at least one intermediate core layer formed from a metallic, composite, or inorganic/organic hybrid composition.

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.

An object of the present invention is to provide a golf ball showing a low spin rate on driver shots and a high spin rate on approach shots. The present invention provides a golf ball having a low hardness part having a hardness in a range from 5 to 40 in Shore D hardness or a lowest hardness point in a core hardness distribution in a region located at a distance from 36.0% to 65.0% of a radius of the golf ball from a center point of the golf ball.

A thermoplastic multi-layer golf ball has a core center including a first thermoplastic material, a core layer including a second thermoplastic material, and a cover including a third thermoplastic material. The core center has a diameter of 21-29 mm and a surface Shore D hardness H1 of less than about 50. The core layer is at least about 5 mm thick with an outer surface Shore D hardness H2 of more than about 50. The cover has an outer surface Shore D hardness H3 of more than about 60. H3 is up to about 20 Shore D units higher than H2, and H2 is up to about 10 Shore D units higher than H1. The core layer has a specific gravity that is at least 0.1 g/cm.sup.3 greater than the specific gravity of the core center.