Golf ball core compositions containing high Vicat softening temperature, resilient thermoplastic materials

A method of forming a portion of a golf ball core which comprises:

• forming a first mixture comprising at least one rubber and at least one thermoplastic or thermoplastic elastomer which is a block polymer comprising copoly(ether-ester), copoly(ether-amide), copoly(ester-amide), copoly(urethane-ether), copoly(urethane-ester), maleic anhydride grafted styrene-ethylene-butylene-styrene copolymers, and mixtures thereof;
• mixing said first mixture at a first temperature sufficient to allow substantially homogeneous mixing of said first mixture;
• cooling said first mixture to a second temperature, wherein said second temperature is below an activation temperature of a free-radical initiator capable of facilitating crosslinking of said first mixture;
• forming a second mixture by adding the first mixture to the free-radical initiator having the activation temperature at a temperature above the second temperature;
• and
• shaping and heating the second mixture to at least the activation temperature to crosslink the second mixture so as to form a portion of a golf ball core.

A golf ball having a coefficient of restitution of at least about 0.7 which comprises:

• a core comprising at least one layer, wherein the at least one layer is formed of a material comprising a vulcanized material composition comprising at least one rubber, a metal salt of an α,β-unsaturated acid, an initiator, and at least one thermoplastic or thermoplastic elastomer having a Vicat-softening temperature of at least about 38° C.;
• and
• a cover disposed concentrically about the core,
• wherein the at least one thermoplastic or thermoplastic elastomer is a block polymer comprising copoly(ether-ester), copoly(ether-amide), copoly(ester-amide), copoly(urethane-ether), copoly(urethane-ester), maleic anhydride grafted styrene-ethylene-butylene-styrene copolymers, and mixtures thereof.