THERMOPLASTIC DUAL CORE HAVING A NEGATIVE GRADIENT INNER CORE AND A NEGATIVE GRADIENT OUTER CORE

摘要

A golf ball includes an inner core layer and an outer core layer. The inner core layer is formed from a first thermoplastic material and has a geometric center hardness that is greater than its surface hardness to define a first negative hardness gradient. The outer core layer is formed from a second thermoplastic material and has an inner surface hardness greater than its outer surface hardness to define a second negative hardness gradient. Inner and outer cover layers are disposed over the outer core layer. The negative hardness gradient of the inner core layer is about −1 to −5 Shore C. The negative hardness gradient of the outer core layer is at least −1 Shore C but less than −7 Shore C. A difference between the inner core layer surface hardness and the outer core layer inner surface hardness is at least −3 Shore C.

主权项

1. A golf ball comprising:
an inner core layer comprising a first thermoplastic material and having a geometric center hardness greater than a surface hardness to define a first negative hardness gradient; an outer core layer disposed about the inner core, the outer core layer comprising a second thermoplastic material and having an inner surface hardness greater than an outer surface hardness to define a second negative hardness gradient; an inner cover layer disposed outer core layer; and an outer cover layer disposed about the inner cover layer, wherein the first negative hardness gradient is from −1 to −5 Shore C, the second negative hardness gradient is at least −1 Shore C but less than −7 Shore C, and a difference between the inner core surface hardness and the outer core inner surface hardness, Δh, is at least −3 Shore C.