The present invention provides a method for arranging dimples on a golf ball surface in which the dimples are arranged in a pattern derived from at least one irregular domain generated from a regular or non-regular polyhedron. The method includes choosing control points of a polyhedron, generating an irregular domain based on those control points, packing the irregular domain with dimples, and tessellating the irregular domain to cover the surface of the golf ball. The control points include the center of a polyhedral face, a vertex of the polyhedron, a midpoint or other point on an edge of the polyhedron and others. The method ensures that the symmetry of the underlying polyhedron is preserved while minimizing or eliminating great circles due to parting lines.

A golf ball 2 includes a core 4, a mid layer 6, a cover 8 and a paint layer 10. The core 4 includes a center 12 and an envelope layer 14. The golf ball 2 satisfies the following mathematical formulas. In the mathematical formulas, Tm represents a thickness of the mid layer, Tcmin represents a minimum thickness of the cover, Tcmax represents a maximum thickness of the cover, and Tp represents a thickness of the paint layer. The golf ball 2 has a large number of dimples 16 on a surface thereof. The number of planes that can divide a pattern of the dimples so that divided patterns are mirror symmetry to each other is one.
Tm>TcmaxTcmin>Tp
(TcmaxTcmin)0.15 mm
0.15(Tp/Tcmin)0.04

The present invention provides the rubber composition for a golf ball comprising (a) a base rubber, (b) a co-crosslinking agent which is an ,-unsaturated carboxylic acid or a metal salt thereof or both, (c) a crosslinking initiator, and (d) an alcohol, in which further (e) a hindered phenol-type antioxidant including a substituent having thioether structure is included and the content of component (e) is at least 0.2 part by weight per 100 parts by weight of component (a), and a golf ball using the rubber composition, in order to achieve the object that good durability of the golf ball to impact is maintained.

The invention provides a rubber composition for golf balls, comprising: (a) a base rubber, (b) a co-crosslinking agent which is an ,-unsaturated carboxylic acid or a metal salt thereof or both, (c) an organic peroxide, (d) water or a moisture-providing agent, (e) a hindered phenol-type antioxidant including a substituent having thioether structure, wherein the content of component (e) is at least 0.2 part by weight per 100 parts by weight of component (a).

An ultra-low compression golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

Multi-piece golf balls containing a multi-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, an intermediate core layer, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. In one preferred embodiment, each core layer has a positive hardness gradient. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof. The intermediate core layer is preferably formed from a thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a thermoplastic composition such as an ethylene acid copolymer. The resulting ball has high resiliency and good spin control.

A golf ball has a large number of dimples 10 on a surface thereof. The dimples 10 include a plurality of small dimples 10S each having an area of less than 8.0 mm.sup.2, and a plurality of large dimples 10L each having an area of equal to or greater than 8.0 mm.sup.2. A ratio PS of a sum of areas of all the small dimples 10S to a surface area of a phantom sphere of the golf ball is less than 2.0%. A ratio PL of a sum of areas of all the large dimples 10L to the surface area of the phantom sphere is equal to or greater than 79.0%. A degree G of uniformity of areas of the large dimples 10L is equal to or less than 1.15.

An ultra-low compression golf ball is disclosed herein. The core preferably has a PGA compression less than 30. The mantle layer and cover have approximately the same thickness. The cover comprises a thermoplastic polyurethane material and has a specific gravity greater than the core and mantle layer. The golf ball has a PGA compression less than 75 and a COR of at least 0.780.

A golf ball capable of reducing the moment of inertial while reducing spin in a driver shot will be provided. To that end, a golf ball of the disclosure is a golf ball having a cover and, provided that I.sub.b (g.Math.cm.sup.2) represents the moment of inertia of the golf ball, (mm) represents deflection hardness corresponding to a deformation amount (mm) of the golf ball in a load direction from when an initial load of 10 kgf is applied to the golf ball to when a final load of 130 kgf is applied to the golf ball, and D represents Shore D hardness of the cover, a spin change amount predictive index S represented by the following formula:

[00001]$.Math..Math.S^{}={\left(\frac{}{D}\right)}^2.Math.\frac{82-I_b}{{82}^2}.Math.{10}^6$

is at least 2.0.

A golf ball 2 has a large number of dimples 8 on a surface thereof. A trajectory of the golf ball 2 is divided into first to fourth segments. An average CD1 of drag coefficients CD and an average CL1 of lift coefficients CL in the first segment are equal to or less than 0.225 and 0.180, respectively. An average CD2 of drag coefficients CD and an average CL2 of lift coefficients CL in the second segment are equal to or less than 0.250 and 0.220, respectively. An average CD3 of drag coefficients CD and an average CL3 of lift coefficients CL in the third segment are equal to or greater than 0.260 and 0.220, respectively. An average CD4 of drag coefficients CD and an average CL4 of lift coefficients CL in the fourth segment are equal to or greater than 0.250 and 0.200, respectively.