| 主权项 |
1. A golf ball comprising a spherical core, a mid layer positioned outside the core, and a cover positioned outside the mid layer, wherein
the core includes an inner core, a mid core positioned outside the inner core, and an outer core positioned outside the mid core, the mid layer includes an inner mid layer and an outer mid layer positioned outside the inner mid layer, a JIS-C hardness H(C) at a point C present outward from a boundary between the inner core and the mid core in a radius direction by 1 mm is equal to or greater than a JIS-C hardness H(B) at a point B present inward from the boundary between the inner core and the mid core in the radius direction by 1 mm, a JIS-C hardness H(E) at a point E present outward from a boundary between the mid core and the outer core in the radius direction by 1 mm is equal to or greater than a JIS-C hardness H(D) at a point D present inward from the boundary between the mid core and the outer core in the radius direction by 1 mm, when an angle (degree) calculated by (Formula 1) from a thickness Y (mm) of the mid core, the hardness H(C), and the hardness H(D) is defined as an angle α and an angle (degree) calculated by (Formula 2) from a thickness Z (mm) of the outer core, the hardness H(E), and a JIS-C hardness H(F) at a point F located on a surface of the core is defined as an angle β:
α=(180°/π)*a tan [{H(D)−H(C)}/Y] (Formula 1); andβ=(180°/π)*a tan [{H(F)−H(E)}/Z] (Formula 2), the angle α is equal to or greater than 0°, and a difference (α−β) between the angle α and the angle β is equal to or greater than 0°, and a Shore D hardness Hm2 of the outer mid layer is greater than a Shore D hardness Hm1 of the inner mid layer. |
