In a golf ball having a core, envelope layer, intermediate layer and cover, the core has a specific hardness profile, the resin materials making up either or both of the envelope layer and the intermediate layer contain a high-acid ionomer, and the Shore C hardness relationships among the core center, surface of the envelope-encased layer and surface of the intermediate layer-encased sphere satisfy the following conditions:
surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere,  (1)
surface hardness of intermediate layer-encased sphere−center hardness of core≥40.  (2)
This ball achieves a good distance on shots with utility and iron clubs, is receptive to spin in the short game, and has a soft feel at impact on all shots, making it useful to amateur golfers.

Golf balls having a single or dual-layered solid core are provided. In one embodiment, the golf ball has dimensions and properties that do not conform to the rules of the United States Golf Association (USGA). For example, the ball weight; ball size; ball spherical symmetry; ball initial velocity; and/or ball overall distance may fall outside of the USGA standards. The dual-layered core can have an inner core comprising a thermoplastic composition and surrounding outer core comprising a thermoset composition. In another embodiment, the dual-layered core has an inner core comprising a thermoplastic composition and outer core comprising a thermoset composition. The thermoplastic composition preferably comprises an ethylene acid copolymer ionomer and plasticizer. The thermoset composition preferably comprises polybutadiene rubber. The ball further includes a cover of at least one layer.

A golf ball can include a core, a mid layer, and a cover. The golf ball can satisfy the following mathematical formulas (1), (2), and (3):
C1≤(124.8−Hs)/11.5  (1)
C2−C1≥(−1/6*C1+(68−H2)/20+(5−Hd)/100)*T2   (2)
10≤H2*T2−H3*T3  (3), where C1 is an amount of compressive deformation (mm) of the core, C2 is an amount of compressive deformation (mm) of a sphere including the core and the mid layer, Hd is Hs−Ho, Ho is a hardness (Shore C) of a center the core, Hs is a hardness (Shore C) of a surface of the core, H2 is a hardness (Shore D) of the mid layer, H3 is a hardness (Shore D) of the cover, T2 is a thickness (mm) of the mid layer, and T3 is a thickness (mm) of the cover.

In a golf ball having a core, envelope layer, intermediate layer and cover, the core has a specific hardness profile, the resin materials making up either or both of the envelope layer and the intermediate layer has a material hardness on the Shore D hardness scale of at least 65 and has a specific gravity of at least 1.05, and the Shore C hardness relationships among the core center, surface of the envelope-encased layer and surface of the intermediate layer-encased sphere satisfy the following conditions:

surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere,  (1)

surface hardness of intermediate layer-encased sphere−center hardness of core≥40.  (2)

This ball achieves a good distance on shots with utility and iron clubs, is receptive to spin in the short game, and has a soft feel at impact on all shots, making it useful to amateur golfers.

A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is formed in a mold having support pins by injection molding. A ratio (V/S) of a volume V (mm.sup.3) of the cover 6 to an amount of compressive deformation S (mm) of the core 4 is not less than 1000 and not greater than 1900. The cover 6 has a shore D hardness of not greater than 62. The golf ball 2 has a plurality of dimples 8 on a surface thereof. A total volume W of these dimples is not less than 490 mm.sup.3 and not greater than 620 mm.sup.3. A ratio (α/P) of a latitude α (degree) of each support pin to a total cross-sectional area P (mm.sup.2) of the support pins is not less than 0.35 and not greater than 0.60.

In a multi-piece solid golf ball having a core, an envelope layer, an intermediate layer and a cover, the envelope layer is formed into two layers—an inner envelope layer and an outer envelope layer. The inner envelope layer-encased sphere, outer envelope layer-encased sphere, intermediate layer-encased sphere and ball have respective surface hardness that satisfy a specific relationship. The inner envelope layer or outer envelope layer is formed primarily of one or more elastomer, and further the core has a particular hardness profile. This ball has an excellent flight when struck by golfers whose head speeds are not that fast and has a good, soft feel at impact, thus making it highly suitable for amateur golfers.

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 envelope layer thickness.  (3) 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.

In a golf ball having a core, envelope layer, intermediate layer and cover, the core has a specific hardness profile, the resin materials making up either or both of the envelope layer and the intermediate layer contain a high-acid ionomer, and the Shore C hardness relationships among the core center, surface of the envelope-encased layer and surface of the intermediate layer-encased sphere satisfy the following conditions:

surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere,  (1)

surface hardness of intermediate layer-encased sphere−center hardness of core≥40.  (2)

This ball achieves a good distance on shots with utility and iron clubs, is receptive to spin in the short game, and has a soft feel at impact on all shots, making it useful to amateur golfers.

An object of the present disclosure is to provide a golf ball having improved flight distance on driver shots and excellent spin performance on approach shots (particularly under the condition that there is grass between the golf ball and the club face) and on middle iron shots. The present disclosure provides a golf ball comprising a spherical core and a cover disposed outside the spherical core, wherein when a center hardness of the spherical core (Shore C hardness), hardnesses at 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm and 15 mm points from a center of the spherical core toward a surface of the spherical core (Shore C hardness), and a surface hardness of the spherical core (Shore C hardness) are represented by H.sub.0, H.sub.2.5, H.sub.5, H.sub.7.4, H.sub.10, H.sub.12.5, H.sub.15 and H.sub.s respectively, the following relation is satisfied:

(H.sub.2.5−H.sub.0)>(H.sub.12.5−H.sub.10)>(H.sub.s−H.sub.15).

An object of the present invention is to provide a golf ball having excellent approach spin performance under a dry condition and excellent approach spin performance under a condition that there is grass between the golf ball and the club face. The present invention provides a golf ball comprising a golf ball body and a paint film formed on a surface of the golf ball body, wherein the paint film is composed of at least one layer, and an outermost paint film layer located at the outermost layer of the golf ball contains, as a base resin, a polyurethane obtained by a reaction between (A) a polyisocyanate composition and (B) a polyol composition, and the outermost paint film layer has a dynamic friction coefficient of from 0.75 to 1.5 measured with a dynamic friction tester under specific conditions.