| 摘要 |
The invention relates to a bi-core containing a zero gradient center and a positive gradient outer core layer. A golf ball comprises an inner core which has a geometric center and a first external surface, with the inner core being made of roughly even first rubber compound, an external core layer which, made of second rubber compound being roughly even, comprises a second external surface, an internal covering layer which surrounds the core and forms materials containing ionomer, and external covering layer which surrounds the inner covering layer to form and include pouring polyureaor or pouring polyurethane. The hardness of the first external surface is over 20 HS smaller than the hardness of the geometric center, thus to limit the negative hardness gradient inner core. Moreover, the hardness of the second external surface is over 18 HS greater than that of the geometric center, thus to limit the positive gradient outer core layer and the shallow positive hardness gradient core. |
