| abstract |
In a golf ball, a single layer core with a gradient from soft to hard as it goes from the surface to the center is realized. In addition, a method for manufacturing such a core inexpensively and efficiently is realized. An inner core comprising a first outer surface and a geometric center, the first formulation being substantially uniform throughout such that its hardness is in the range of 45 Shore C to 65 Shore C Substantially as formed throughout the inner core layer, having a second outer surface and an inner surface, and having a hardness in the range of 55 Shore C to 90 Shore C. And an outer core layer manufactured from a second uniform formulation. A cover layer is disposed around the outer core layer. The hardness of the first outer surface is equal to or smaller than the hardness of the geometric center to form a “negative hardness gradient”, and the hardness of the second outer surface is greater than the hardness of the inner surface and is “positive hardness” A “gradient” is formed. [Selection] Figure 3 |