GOLF BALL HAVING A HOLLOW CENTER
A hollow golf ball includes a spherical inner core shell layer formed from a first thermoplastic composition, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center. An outer core layer is formed about the shell layer and includes a thermoset rubber composition. An inner cover layer is formed about the outer core layer and includes an ionomeric material. An outer cover layer is formed about the inner cover layer. The outer cover includes a polyurea or a polyurethane and has a hardness less than the inner cover layer. 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 thermoset outer core layer has a second hardness gradient.
1 . A golf ball comprising a hollow core, the golf ball comprising:
a spherical inner core shell layer formed from a first thermoplastic composition, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center;
an outer core layer disposed about the shell layer, the outer 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 thermoset outer core layer has a second hardness gradient.
2 . The golf ball of claim 1 , wherein the second hardness gradient is about 0 Shore C.
3 . The golf ball of claim 1 , wherein the second hardness gradient is a negative hardness gradient of about 3 to 25 Shore C.
4 . The golf ball of claim 1 , wherein the second hardness gradient is a positive hardness gradient of about 3 to 25 Shore C.
5 . A golf ball comprising a hollow core, the golf ball comprising:
a spherical inner core shell layer formed from a first thermoplastic composition, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center;
a thermoset outer core layer;
an intermediate core layer comprising a second thermoplastic material disposed between the thermoplastic shell layer and the thermoset outer core layer;
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 thermoset outer core layer has a second hardness gradient.
6 . The golf ball of claim 5 , wherein the second hardness gradient is about 0 Shore C.
7 . The golf ball of claim 5 , wherein the second hardness gradient is a negative hardness gradient of about 3 to 25 Shore C.
8 . The golf ball of claim 5 , wherein the second hardness gradient is a positive hardness gradient of about 3 to 25 Shore C.
9 . A golf ball comprising a hollow core, the golf ball comprising:
a spherical inner core shell layer formed from a first thermoplastic composition, the shell layer having an outer surface, an inner surface, and an inner diameter to define a hollow center;
a first thermoset outer core layer;
a second thermoset intermediate core layer disposed between the thermoplastic shell layer and the thermoset outer core layer;
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, and the shell layer has a surface hardness and an inner surface hardness, the surface hardness being greater than the inner surface hardness by about 1 to 5 Shore C to define a shallow positive hardness gradient, and the thermoset outer core layer or thermoset intermediate core layer has a second hardness gradient.
10 . The golf ball of claim 9 , wherein the second hardness gradient is about 0 Shore C.
11 . The golf ball of claim 9 , wherein the second hardness gradient is a negative hardness gradient of about 3 to 25 Shore C.
12 . The golf ball of claim 9 , wherein the second hardness gradient is a positive hardness gradient of about 3 to 25 Shore C.