| abstract |
A golf ball including a spherical inner core shell layer formed from a thermoset rubber composition, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center. A thermoplastic outer core layer is formed about the shell layer. An optional inner cover layer is formed about the outer core layer, the inner cover including an ionomeric material. An outer cover layer is formed over the core or option inner cover layer, the outer cover including a polyurea or a polyurethane and having a second hardness less than the optional inner cover layer. The hollow center has a diameter of about 0.15 to 1.1 inches. The shell layer has a surface hardness greater than its inner surface hardness by about 3 to 25 Shore C to define a hardness gradient, and the thermoplastic outer core layer has a second hardness gradient. |