A golf ball includes a spherical core, a mid layer, an inner cover, and an outer cover. A hardness Hm of the mid layer is greater than a hardness Hinc of the inner cover which is greater than a hardness Houc of the outer cover. A difference (HmHouc) is greater than 25. A volume Vm of the mid layer is greater than a volume Vinc of the inner cover which is greater than a volume Vouc of the outer cover. A ratio [(Vm+Vinc+Vouc)/V] of a sum (Vm+Vinc+Vouc) relative to a volume V of an entirety of the golf ball is less than 0.30. A ratio (Vm/Vouc) is greater than 1.50. A product (Vm*Hm) and a product (Vouc*Houc) meet the following relationship: [(Vm*Hm)/(Vouc*Houc)]>3.0.

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-layered golf balls having a core, intermediate layer, and cover are provided. The ball includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An intermediate layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. The foamed intermediate layer may have a specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. Ball constructions having two intermediate layers, wherein at least one layer is a foamed layer can be made. A cover having at least one layer is disposed about the intermediate layer.

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 T3, 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.

Multi-layered golf balls having a core made of a foamed composition, preferably polyurethane foam, are provided. The ball includes a dual-layered core having a foam inner core (center) and surrounding outer core layer. The outer core layer may be made from a non-foamed thermoset material such as polybutadiene rubber. The ball further includes an inner cover, preferably made from an ionomer composition comprising an O/X-type acid copolymer, wherein O is -olefin, and X is a C.sub.3-C.sub.8 ,-ethylenically unsaturated carboxylic acid. The outer cover may be made from a non-foamed thermoset or thermoplastic material such as polyurethane. Preferably, the specific gravity of the inner cover is greater than the specific gravity of the outer core, which is greater than the specific gravity of the inner core. The finished ball has good distance and low-spin properties.

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.

A golf ball 2 includes a core 4, one or more mid layers 6, a cover 8, and dimples 10. A central hardness Ho and a surface hardness Hs of the core 4, a hardness Hm(min) of a layer having a lowest hardness among the mid layers 6, and a hardness Hc of the cover 8 satisfy the following mathematical formulas (1) to (4).

HsHo>15(1)

HcHm(min)>20(2)

10<Hm(min)Ho<15(3)

5<HcHs<20(4)

An occupation ratio So and a ratio Rs of a number of the dimples 10 each having a diameter of from 9.60% to 10.37% of a diameter of the golf ball 2, relative to a total number of the dimples 10, satisfy the following mathematical formula (5).

Rs2.5*So+273(5)

The present invention provides methods for producing molded golf balls and the resultant balls. The methods of this invention involve producing foamed polyurethane covers and these methods help reduce dimple distortions and other surface imperfections. These golf balls contain an inner core and outer foamed polyurethane cover. One or more intermediate layers can be disposed between the core and cover. In one embodiment, a castable liquid polyurethane composition containing a foaming agent is dispensed into mold cavities, which are then pressed together to form a foam cover for the ball.

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 ball having a core and a cover of one or more layers, the core being formed of a material molded under heat from a rubber composition including a base rubber, an organic peroxide, and water and/or a metal monocarboxylate. Defining the tan slope as (tan .sub.10tan .sub.1)/(10%1%), where tan .sub.1 and tan .sub.10 are the loss tangents at dynamic strains of, respectively, 1% and 10% when the loss tangents of the core center and the core surface are measured at 12 C. and 15 Hz, the difference between the tan slopes at the core surface and the core center is larger than 0.002. Because a core material which undergoes little decrease in resilience over time and experiences little energy loss can be obtained, the golf ball maintains a good rebound, has a reduced spin rate and thus is able to achieve an increased distance.