Golf ball having a thermoplastic positive hardness gradient inner core layer and a thermostat shallow positive hardness gradient outer core layer

摘要

A golf ball has an inner core layer including a thermoplastic highly-neutralized ionomer and having a geometric center hardness less than a surface hardness to define a first positive hardness gradient. An outer core layer is formed about the inner core and includes a homogenous thermoset composition. The outer core has an interior hardness less than an outer surface hardness to define a second positive hardness gradient. An inner and outer cover layers are disposed about outer core layer. The first and second hardness gradients each have a slope and the slope of the second hardness gradient is less than the slope of the first hardness gradient such that a ratio of the first and second slopes is 0.8 to 0.85.

主权项

1. A golf ball comprising:
an inner core layer comprising a thermoplastic highly-neutralized ionomer comprising a copolymer of ethylene and an α,β-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to neutralize the acid groups of the copolymer by 70% or greater, and having a geometric center hardness less than a surface hardness to define a first positive hardness gradient; an outer core layer disposed about the inner core, the outer core being formed from a homogenous thermoset composition and having an interior hardness less than an outer surface hardness to define a second positive hardness gradient; an inner cover layer disposed about outer core layer; and an outer cover layer disposed about the inner cover layer, wherein the second hardness gradient is greater than or equal to the first hardness gradient.