GOLF BALLS HAVING A CORE LAYER MADE FROM PLASTICIZED THERMOPLASTIC COMPOSITIONS

摘要

Multi-layered golf balls containing a dual-core structure are provided. The core structure includes an inner core (center) comprising a thermoplastic composition, preferably including: a) ethylene acid copolymer, b) plasticizer, and c) cation source. Preferably, a fatty acid ester such as ethyl oleate is used as the plasticizer. The outer core layer is preferably formed from a thermoset composition such as polybutadiene rubber. The core layers have different hardness levels. The core assembly preferably has a positive hardness gradient extending across the entire assembly. The core structure and resulting ball have relatively good resiliency at given compressions.

主权项

1. A core assembly for a golf ball, comprising:
i) an inner core layer comprising a thermoplastic composition, the inner core having an outer surface hardness (Hinner core surface) and a center hardness (Hinner core center), the Hinner core surface being greater than the Hinner core center to provide a positive hardness gradient, the thermoplastic composition comprising;
a) an acid copolymer of ethylene and an α,β-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates;b) a plasticizer; andc) a cation source present in an amount sufficient to neutralize from about 0 to about 100% of all acid groups present in the composition; and ii) an outer core layer comprising a thermoset rubber composition, the outer core layer being disposed about the inner core layer and having an outer surface hardness (Houter surface of OC) and a midpoint hardness (Hmidpoint of OC), the Houter surface of OC being greater than the Hmidpoint of OC to provide a positive hardness gradient, wherein the center hardness of the inner core (Hinner core center) is in the range of about 10 Shore C to about 70 Shore C and the outer surface hardness of the outer core layer (Houter surface of OC) is in the range of about 20 Shore C to about 95 Shore C to provide a positive hardness gradient across the core assembly.