abstract |
A golf ball includes a unitary core having an outer surface, a geometric center, and a soft transition region adjacent to the outer surface, and is formed from a substantially homogenous composition. The ball further includes an outer cover layer. The soft transition region has a thickness of up to 4 mm, has about 8 to 20 percent trans-polybutadiene isomer, and has a negative hardness gradient of up to 15 Shore C. The core has an overall negative hardness gradient of up to 20 Shore C and has a gradient quotient, GQ, defined by the equation: n n n n n n n G n + n T n n n 10 n × n COR n n n ≤ n 7 n n n n n where G is the overall negative hardness gradient in Shore C, T is the percent of trans-polybutadiene isomer at the core outer surface, and COR is the coefficient of restitution measured at an incoming velocity of 125 ft/s. |