Thermoplastic dual core having a positive gradient inner core and a negative gradient outer core

Abstract

A golf ball includes an inner core layer formed from a first thermoplastic material and having a geometric center hardness less than a surface hardness to define a positive hardness gradient. An outer core layer is disposed about the inner core and is formed from a second thermoplastic material. The outer core layer has a surface hardness less than a hardness at a point about 0.5 to 2 mm from an interface between the inner core layer and the outer core layer to define a negative hardness gradient. An inner cover layer is disposed outer core layer and an outer cover layer is disposed about the inner cover layer. The positive hardness gradient os the inner core layer is up to about 10 Shore C and the negative hardness gradient of the outer core layer is less than about 10 Shore C.

Dependencies are inferred from the claim text.