Abstract: Multi-layered, golf balls having a core made of a particle-based polyurethane foam composition are provided. The ball includes a dual-layered core having a foam inner core (center) and surrounding outer core layer. The surrounding outer core layer may be made from a non-foamed thermoset material such as polybutadiene rubber. In one embodiment, pre-expanded thermoplastic polyurethane foam beads containing a blowing agent are used to form the foam center. In another embodiment, pre-formed polyurethane foam particles are used. The foam cores have good resiliency, thermal stability, and durability over a wide temperature range. The ball further includes a cover that may be multi-layered.

Abstract: A golf ball including an inner core having a first outer surface and a geometric center and being formed from a first substantially homogenous composition such that the inner core has a hardness of about 60 Shore C to about 90 Shore C; an outer core layer disposed about the inner core having a second outer surface and being formed from a second substantially homogenous composition such that the outer core layer has a hardness of about 60 Shore C to about 95 Shore C; and a cover layer disposed about the outer core layer. The geometric center and first and second outer surfaces each have a hardness, the hardness of the second outer surface being lower than the hardness of the geometric center to define a negative hardness gradient.