In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the core is formed 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, in terms of Shore C hardness values, satisfies the following two conditions:

material hardness of cover>material hardness of intermediate layer, and

material hardness of envelope layer≥surface hardness of core; and

the thickness relationship among the layers satisfies the following condition:

(cover thickness intermediate layer thickness)<envelope layer thickness.

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 golf ball having a core, envelope layer, intermediate layer and cover, the (core diameter)/(ball diameter) value falls within a particular range, the core has a specific hardness profile, and the Shore C hardness relationships among the core center and surface hardnesses and the surface hardnesses of the envelope layer-encased sphere, intermediate layer-encased sphere and ball satisfy the following conditions:
core surface hardness<surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness,  (1)
(surface hardness of envelope layer-encased sphere)−(core center hardness)≥28.  (2)
Also, the envelope layer, intermediate layer and cover have respective thicknesses which satisfy the condition:
cover thickness<intermediate layer thickness  (3)
cover thickness<envelope layer thickness  (4)
envelope layer thickness≥0.8 mm.  (5)
This ball enables mid-level and skilled amateur golfers to achieve superior distances on driver shots and on iron shots, and moreover has a soft yet good feel at impact.

A golf ball comprising layers that have from 0.05% to 70% by weight of a radio-opaque filler, and wherein the concentration of the radio-opaque filler is measurably different in each layer is disclosed herein. The radio-opaque filler is preferably a compound based on barium, bismuth, tungsten, iodine, or reduced iron.

In a golf ball having a core, an envelope layer, an intermediate layer and a cover, the core, the envelope layer-encased sphere obtained by encasing the core with the envelope layer, the intermediate layer-encased sphere obtained by encasing the envelope layer-encased sphere with the intermediate layer and the ball obtained by encasing the intermediate layer-encased sphere with the cover have respective deflections when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) which satisfy specific conditions. This ball achieves a good distance on shots with a utility club and with irons, is receptive to spin in the short game and has a soft feel at impact on all shots, making it useful to amateur golfers.

Multi-layered golf balls having at least one layer made of a foamed silicone composition are provided. Multi-layered golf balls having at least one layer made of non-foamed silicone elastomer composition also are provided. For example, three-piece, four-piece, and five-piece golf balls containing different core and cover structures can be made. The foamed silicones have good thermal stability and durability without sacrificing resiliency. The non-foamed silicone elastomers have high elongation, tensile strength, chemical/fluid-resistance, and weatherability properties. These compositions can be used to form any layer, for example, core, intermediate, or cover, in the golf ball.

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

A golf ball 2 includes a core 4, a mid layer 6, a cover 8, and dimples 10. A difference DH in hardness between a surface and a central point of the core 4, a thickness Tm and a hardness Hm of the mid layer 6, a thickness Tc and a hardness Hc of the cover 8, and an amount of compressive deformation Sb meet the following mathematical formulas.

(DH*Hm)/(Hc*Tc)>80

((Sb*Tc)/(Hc* Hm*Tm))*1000>0.75

An area ratio So of dimples 10 and a ratio Rs of a number of the dimples 10 each having a diameter of equal to or greater than 9.60% but equal to or less than 10.37% of a diameter of the golf ball 2 meet the following mathematical formula (3).

Rs≧−2.5*So+273   (3)

A golf ball includes: a radio frequency identification (RFID) tag including an IC chip and an antenna; a protection layer surrounding the outer periphery of the RFID tag; a relaxation layer surrounding the outer periphery of the protection layer; a core surrounding the outer periphery of the relaxation layer; and a cover surrounding the outer periphery of the core. The curing temperature of the protection layer is 60° C. or less, and the protection layer is formed with a material having a hardness of Shore D 60 or more. The relaxation layer is formed with a thermoplastic elastomer-based material having a hardness with a difference from a hardness of a surface of the core on a side contacting the relaxation layer of Shore D 20 or less.

A rubber composition for golf balls includes (A) a base rubber, (B) two different metal salts of α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms, (C) a metal salt in which at least one bonding site is a fatty acid of 9 or more carbon atoms, and (D) a crosslinking initiator. Letting component (B) include (B-1) an unsaturated metal carboxylate in a high compounding weight and (B-2) an unsaturated metal carboxylate in a low compounding weight, the ratio (B-2)/(B-1) is from 4 to 20 wt % and the ratio (B-2)/(C) is from 20 to 115 wt %. By using this rubber composition in a golf ball core, the golf ball can be endowed with both good spin properties and good durability on impact.

Provided is a golf ball is excellent in flight distance performance, approach performance, and feel at impact. A ball 2 includes a core 4, a mid layer 6, and a cover 8. The core 4 includes an inner core 10 and an outer core 12. The cover 8 includes an inner layer cover 10 and an outer layer cover 12. An inner core volume Vc, a mid layer volume Vm, a mid layer hardness Hm, an inner layer cover volume Vinc, an inner layer cover hardness Hinc, an outer layer cover volume Vouc, an outer layer cover hardness Houc, and a ball volume V meet the following relational expressions (a) to (g): (a) Vc/V<0.07, (b) Hm>Hinc>Houc, (c) Hm−Houc>25, (d) Vm>Vinc>Vouc, (e) (Vm+Vinc+Vouc)/V<0.30, (f) Vm/Vouc>1.50, and (g) (Vm*Hm)/(Vouc*Houc)>3.0.