US Patent 9,056,228
Variable density core golf balls
Abstract
A golf ball is provided having a modified density gradient among the inner layers to produce a desired high or low moment of inertia and controlled spin rate is disclosed. The golf ball has three or more inner layers in addition to a cover, and the density of the inner layers is selected such that the layers inside the cover have a density progression from the core to the cover or from the cover to the core.