A golf ball includes a core, a mid layer, and a cover. A ratio R1 calculated by mathematical formula (1): R1=(Df1−Df2)/(Df2−Df3) is not less than 5.00. A ratio R2 calculated by mathematical formula (2): R2=(T2*H2)/H3 is not less than 2.00. A ratio R3 calculated by mathematical formula (3): R3=D1/T3 is not less than 50. In mathematical formulas (1) to (3), Df1 represents an amount of compressive deformation of the core, Df2 represents an amount of compressive deformation of a sphere including the core and the mid layer, Df3 represents an amount of compressive deformation of the golf ball, T2 represents a thickness of the mid layer, H2 represents a hardness of the mid layer, H3 represents a hardness of the cover, D1 represents a diameter of the core, and T3 represents a thickness of the cover.

Golf balls including a plurality of radar detectable marks disposed on any single layer or among two or more layers thereof are provided. When all of the radar detectable marks present on any layer of the ball are radially projected onto the outer surface of the ball, the resulting overall pattern of projected radar detectable marks includes a series of three or marks located on a 1.5 mm wide great circle band on the outer surface of the ball.

Golf balls including a plurality of radar detectable marks disposed on any single layer or among two or more layers thereof are provided. When all of the radar detectable marks present on any layer of the ball are radially projected onto the outer surface of the ball, the resulting overall pattern of projected radar detectable marks includes a series of three or marks located on a 1.5 mm wide great circle band on the outer surface of the ball.

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.

An object of the present disclosure is to provide a golf ball having good shot feeling and excellent durability and not having lowered resilience even if a hard cover material is used. The present disclosure provides a golf ball comprising a spherical core, and a cover disposed outside the spherical core and composed of one or more layers, wherein at least one cover layer contains (A) a base resin, and (B) at least one member selected from the group consisting of a polyrotaxane, a polyethylene oxide, a polypropylene oxide, a polycaprolactone and a liquid polymer, and Sa×Spc≥100 wherein Sa (μm) is an arithmetic mean roughness of a surface of a cut plane of the cover, and Spc (mm.sup.−1) is an arithmetic mean curvature of a summit of the surface of the cut plane of the cover.

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

Golf balls having a multi-layered core made of a foamed composition are provided. The core assembly preferably includes a foam inner core (center) and surrounding outer core layer. Preferably, a polyurethane foam composition is used to form the foam center. The core layers have different hardness gradients and specific gravity values. The foamed inner core assembly includes a geometric center, outer surface (skin), and thermal barrier layer that helps protect the foamed center region from the negative effects of high temperatures used during the ball-manufacturing process. Non-foamed thermoset materials such as polybutadiene rubber may be used to form the thermal barrier layer. The foam cores have good resiliency, thermal stability, and durability over a wide temperature range. The ball further includes a cover that may be multi-layered.

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

A method for forming a golf ball provides a core member comprising a core of a golf ball into a cavity of a mold so that the core member is supported by a movable holding pin disposed in the mold; forming a layer outside the core member by injecting a material of the layer into the cavity; and retracting the pin from the cavity into the mold during the material injection so that a portion projecting from a surface of the layer is formed by a tip of the pin, the projecting portion having a site area of at least 0.2% in relation to an entire area of the tip of the pin and having a height of at least 0.2 mm. This method can be implemented by controlling the retraction of the pin, or alternatively by using the pin having a predetermined indentation portion on the tip.

An object of the present invention is to provide a golf ball striking a good balance between flight distance on driver shots and spin rate on approach shots, and excellent in stain resistance and shot feeling. The present invention provides a golf ball comprising a paint film, wherein a base resin of the paint film contains a polyurethane obtained by a reaction between a polyisocyanate composition and a polyol composition containing a urethane polyol having a polyether diol with a number average molecular weight in a range from 800 to 3,000 as a constituent component, and the following requirements are satisfied:
Mp≦200×X−75
Mp≦100
Minm−Moum>40
Moum−Mc<5
Tinm≧Toum>Tc>Tp
(Tinm×Minm)/(Toum×Moum)>2.0
(Toum×Moum)/(Tc×Mc)<3.0
(Tc×Mc)/(Tp×Mp)>10.0
[where Mp, Minm, Moum, and Mc represent a 10% elastic modulus (kgf/cm.sup.2) of the paint film, inner intermediate layer, outer intermediate layer and cover, respectively; Tp, Tinm, Toum, and Tc represent a thicknesses (mm) of the paint film, inner intermediate layer, outer intermediate layer and cover, respectively; and X represents a molar ratio (NCO/OH) of a NCO group in the polyisocyanate composition to a OH group in the polyol composition.].