GOLF BALL COMPOSITIONS
Disclosed herein are soft and stiff compositions, i.e., compositions which have a flexural modulus that is greater than the value that is expected based on the composition's hardness. The compositions preferably have a hardness/modulus relationship represented by the formula H ≦11.889 Ln( M )+42, where H is the hardness of the composition, in JIS-C, and M is the flexural modulus of the composition, in ksi; or a softness/stiffness relationship represented by the formula if M <56, then H ≦8.5218 Ln( M )+26.5 if M ≧56, then H ≦8.5218 Ln( M )+28.5, where H is the hardness of the composition, in Shore D, and M is the flexural modulus of the composition, in ksi.
1 . A golf ball comprising:
a core having an outer surface and a geometric center and being formed from a substantially homogeneous formulation; and
a cover layer;
wherein the difference between the Shore C hardness of the outer surface of the core and the Shore C hardness of the center of the core is 8 or less;
and wherein the cover layer is formed from a thermoplastic composition having a JIS-C hardness (H) and a flexural modulus in ksi (M) wherein H≦11.889 Ln(M)+42, and wherein M>6 ksi.
2 . The golf ball of claim 1 , wherein H≦11.889 Ln(M)+41.
3 . The golf ball of claim 1 , wherein H≦11.889 Ln(M)+40.
4 . The golf ball of claim 1 , wherein M>40 ksi.
5 . The golf ball of claim 4 , wherein H≦9.45 Ln(−0.0105M 2 +3.95M−14)+40.
6 . A golf ball comprising:
an inner core layer having an outer surface and a geometric center and being formed from a first substantially homogeneous formulation;
an outer core layer having an outer surface and an inner surface and being formed from a second substantially homogeneous formulation; and
a cover layer;
wherein the difference between the Shore C hardness of the outer surface of the inner core layer and the Shore C hardness of the center of the inner core layer is 8 or less;
and wherein the cover layer is formed from a thermoplastic composition having a JIS-C hardness (H) and a flexural modulus in ksi (M) wherein H≦11.889 Ln(M)+42, and wherein M>6 ksi.
7 . The golf ball of claim 6 , wherein the difference between the Shore C hardness of the outer surface of the outer core layer and the Shore C hardness of the inner surface of the outer core layer is 5 or less.
8 . The golf ball of claim 6 , wherein H≦11.889 Ln(M)+41.
9 . The golf ball of claim 6 , wherein H≦11.889 Ln(M)+40.
10 . The golf ball of claim 6 , wherein M>40 ksi.
11 . The golf ball of claim 10 , wherein H≦9.45 Ln(−0.0105M 2 +3.95M−14)+40.
12 . A golf ball comprising:
a core having an outer surface and a geometric center and being formed from a substantially homogeneous formulation;
an intermediate layer; and
a cover layer;
wherein the difference between the Shore C hardness of the outer surface of the core and the Shore C hardness of the center of the core is 8 or less;
and wherein the intermediate layer is formed from a thermoplastic composition having a JIS-C hardness (H) and a flexural modulus in ksi (M) wherein H≦11.889 Ln(M)+42, and wherein M>6 ksi.
13 . The golf ball of claim 12 , wherein H≦11.889 Ln(M)+41.
14 . The golf ball of claim 12 , wherein H≦11.889 Ln(M)+40.
15 . The golf ball of claim 12 , wherein M>40 ksi.
16 . The golf ball of claim 15 , wherein H≦9.45 Ln(−0.0105M 2 +3.95M−14)+40.
17 . A golf ball comprising:
an inner core layer having an outer surface and a geometric center and being formed from a first substantially homogeneous formulation;
an outer core layer having an outer surface and an inner surface and being formed from a second substantially homogeneous formulation;
an intermediate layer; and
a cover layer;
wherein the difference between the Shore C hardness of the outer surface of the inner core layer and the Shore C hardness of the center of the inner core layer is 8 or less;
and wherein the intermediate layer is formed from a thermoplastic composition having a JIS-C hardness (H) and a flexural modulus in ksi (M) wherein H≦11.889 Ln(M)+42, and wherein M>6 ksi.
18 . The golf ball of claim 17 , wherein the difference between the Shore C hardness of the outer surface of the outer core layer and the Shore C hardness of the inner surface of the outer core layer is 8 or less.
19 . The golf ball of claim 17 , wherein H≦11.889 Ln(M)+41.
20 . The golf ball of claim 17 , wherein H≦11.889 Ln(M)+40.
21 . The golf ball of claim 17 , wherein M>40 ksi.
22 . The golf ball of claim 21 , wherein H≦9.45 Ln(−0.0105M 2 +3.95M−14)+40.