Provided is a golf ball showing a low spin rate on driver shots and a high spin rate on approach shots. Also provided is a multi-piece golf ball comprising a center and n (n is a natural number of 3 or more) envelope layers covering the center, wherein material hardness of the envelope layers satisfies H2<H0<Hn1; where the envelope layers formed in order from the center side are referred to as a first envelope layer, a second envelope layer, a third envelope layer, a fourth envelope layer, . . . an n1th envelope layer and an nth envelope layer (the outmost layer), respectively and H0 is a material hardness (Shore D hardness) of the center, and H1, H2, H3, H4, . . . Hn1 and Hn are material hardness (Shore D hardness) of the first envelope layer, the second envelope layer, the third envelope layer, the fourth envelope layer, . . . the n1th envelope layer and the nth envelope layer (the outmost layer), respectively; and the center is formed from a thermoplastic resin composition, and the second envelope layer is formed from a thermoplastic resin composition or a rubber composition.

A method of forming a golf ball comprising at least one layer consisting of at least one of a thermoset or thermoplastic composition comprising the steps of: providing a subassembly having at least one of an innermost surface or an outermost surface; providing at least one polymeric mixture P.sub.c comprising a plurality of particles having a softening, melting and/or reacting temperature M.sub.p; heating a fluid with a heat source that does not contact P.sub.c to a temperature M.sub.ph wherein M.sub.pM.sub.ph to form a heated fluid; softening, melting and/or reacting the plurality of particles by mixing each polymeric mixture P.sub.c with at least one heated fluid and forming at least one heated mixture P.sub.cs; and propelling each P.sub.cs onto at least one of the innermost surface or the outermost surface to form a thermoset and/or thermoplastic layer T.sub.mpl about the outermost surface which may be comprised of a heterogeneous composition. The thickness of T.sub.mpl may be from about 3 mils to about 0.10 in.

A golf ball includes a spherical body and intersection surfaces. The intersection surfaces intersect with a spherical surface centered on the center of the spherical body, and are formed as conductive intersection surfaces having conductivity. The spherical surface is formed to have a smaller diameter than a diameter of the spherical body, and the conductive intersection surface is formed on an outer side in the radial direction of the spherical surface. The intersection surfaces intersect with a spherical surface centered on the center of the spherical body, and are formed as conductive intersection surfaces having conductivity. The conductive intersection surface is formed by both side surfaces of the annular body, and so the conductive intersection surface is formed to be continuous around the entire circumferential length of the spherical surface in the circumferential direction.

Casing compositions including carboxylic acid groups, cover compositions including an adhesion promoter with functional groups that crosslink with carboxylic acid groups, and golf balls made from such compositions that have crosslinks between functional groups of the cover compositions and the carboxylic acid groups. The type and concentration of the components in the casing and cover compositions, including the adhesion promoter, affect the adhesion between golf balls having components made from such compositions and, thus, can be used to produce a golf ball having increased durability. Additionally, methods of crosslinking casing and cover layers made from such casing and cover compositions to increase interlayer adhesion are disclosed.

A method of forming a golf ball includes forming a core using a 3D printer, and molding a cover in a surrounding position over the core through at least one of compression molding and injection molding. The core may be formed by printing a first core portion, printing a second core portion, and fusing the first core portion with the second core portion to form the core. Each of the first and second core portions may respectively include a plurality of concentric shells that are sequentially constructed.

A method of forming a golf ball comprising at least one layer consisting of at least one of a thermoset or thermoplastic composition comprising the steps of: providing a subassembly having at least one of an innermost surface or an outermost surface; providing at least one polymeric mixture P.sub.c comprising a plurality of particles having a softening, melting and/or reacting temperature M.sub.p; heating a fluid with a heat source that does not contact P.sub.c to a temperature M.sub.ph wherein M.sub.pM.sub.ph to form a heated fluid; softening, melting and/or reacting the plurality of particles by mixing each polymeric mixture P.sub.c with at least one heated fluid and forming at least one heated mixture P.sub.cs; and propelling each P.sub.cs onto at least one of the innermost surface or the outermost surface to form a thermoset and/or thermoplastic layer T.sub.mpl about the outermost surface which may be comprised of a heterogeneous composition. The thickness of T.sub.mpl may be from about 3 mils to about 0.10 in.

An object of the present invention is to provide a golf ball having an excellent initial velocity when being hit at a head speed of 50 m/sec and an improved initial velocity when being hit at a head speed of 40 m/sec. The present invention provides a golf ball comprising a spherical core and a cover covering the spherical core, wherein the golf ball has a rebound equivalence energy ratio (R.sub.40) ranging from 65.50% to 99.0% at a deformation amount of 7%, and a rebound equivalence energy ratio (R.sub.50) ranging from 20.0% to 70.0% at a deformation amount of 19%, in a compression test (measurement temperature: 70 C., compression speed: 30 mm/min) applying a load to the golf ball along a radial direction of the golf ball.

Multi-piece golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a foam composition, preferably foamed polyurethane. The outer core layer is preferably formed from a non-foamed thermoset composition such as polybutadiene rubber. The inner and outer core layers can have different hardness gradients. Preferably, the specific gravity (density) of the foam inner core is less than the density of the outer core layer. The ball further includes a cover of at least one layer and may include at least one casing layer. The core structure and resulting ball have relatively good resiliency.

A golf ball is disclosed herein that includes at least one radar detectable mark such that a projected pattern is formed when the at least one radar detectable mark is radially projected onto an outer surface of the golf ball. The projected pattern can have a first wave profile mapped along a path defined by a first spherical arc on the outer surface of the golf ball. The projected pattern can comprise at least one first crest and at least one first trough. The projected pattern can have a periodic function selected from: a sine wave, a sawtooth wave, a triangle wave, or a square wave.

Golf balls including one or more layers having at least one radar detectable mark disposed on the surface thereof are provided.