Golf ball having a hollow center

A golf ball comprising a hollow core, the golf ball comprising:

• a spherical inner core shell layer comprising a first thermoplastic material, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center;
• an outer core layer comprising a second thermoplastic material;
• an intermediate core layer disposed between the shell layer and the outer core layer, the intermediate layer comprising a third thermoplastic material different from the first and second;
• an inner cover layer disposed about the outer core layer, the inner cover comprising an ionomeric material and having a first hardness;
• and
• an outer cover layer disposed about the inner cover layer, the outer cover comprising a polyurea or a polyurethane and having a second hardness less than the first;
• wherein the hollow center has a diameter of about 0.15 to 1.1 inches, the shell layer has a surface hardness greater than an inner surface hardness by about 0 to 5 Shore C to define a first hardness gradient, and at least one of the thermoplastic outer core layer or the thermoplastic intermediate layer has a second hardness gradient different from the first.

A golf ball comprising a hollow core, the golf ball comprising:

• a spherical inner core shell layer comprising a first thermoplastic material, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center;
• an outer core layer comprising a second thermoplastic material;
• an intermediate core layer disposed between the shell layer and the outer core layer, the intermediate core layer comprising a thermoset rubber composition;
• an inner cover layer disposed about the outer core layer, the inner cover comprising an ionomeric material and having a first hardness;
• and
• an outer cover layer disposed about the inner cover layer, the outer cover comprising a polyurea or a polyurethane and having a second hardness less than the first;
• wherein the hollow center has a diameter of about 0.15 to 1.1 inches, the shell layer has a surface hardness greater than an inner surface hardness by about 0 to 5 Shore C to define a first hardness gradient, and the thermoplastic outer core layer has a second hardness gradient.