Golf balls having a core layer made from plasticized thermoplastic compositions

A molded sphere comprising a thermoplastic composition, the 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;
• and c) a cation source present in an amount sufficient to neutralize from about 0 to about 100% of all acid groups present in the composition, wherein the sphere has a Coefficient of Restitution of at least about 0.750;
• and a Shore C surface hardness of about 10 to about 75.

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;
• and
• c) 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 the same or less than the Hmidpoint of OC to provide a zero or negative 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 25 Shore C to about 95 Shore C to provide a positive hardness gradient across the core assembly.

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 the same or less than the Hinner core center to provide a zero or negative 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;
• and
• c) 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 25 Shore C to about 95 Shore C to provide a positive hardness gradient across the core assembly.