Golf balls having particle-based foam center

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 is preferably made from a foamed composition. In one embodiment, pre-expanded thermoplastic polyurethane foam beads containing a blowing agent are used to form the foam center and outer core. In another embodiment, pre-formed polyurethane foam particles are used in both core layers. 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.

We claim: 
     
         1 . A core assembly for a golf ball, comprising:
 i) an inner core layer comprising a particle-based polyurethane foam composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches and a specific gravity (SG inner ) and a center hardness (H inner core center ); and   ii) an outer core layer comprising a foamed thermoset or thermoplastic material, the outer core layer being disposed about the intermediate core layer and having a thickness in the range of about 0.100 to about 0.750 inches, and a specific gravity (SG outer ) and an outer surface hardness (H outer surface of OC ), wherein the SG outer , is greater than the SG inner , and the H inner core center  is in the range of about 10 to about 60 Shore C and the H outer surface of OC  is in the range of about 45 to about 96 Shore C to provide a positive hardness gradient across the core assembly.   
     
     
         2 . The core assembly of  claim 1 , wherein the outer core layer comprises a second particle-based polyurethane foam composition. 
     
     
         3 . The core assembly of  claim 1 , wherein the outer core layer comprises a foamed thermoplastic highly neutralized ionomer composition.