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 center formed from a first thermoplastic composition;
an intermediate core layer formed from a thermoset rubber composition;
an outer core layer formed from a second thermoplastic composition; and
a cover;
wherein at least one of the first thermoplastic composition and the second thermoplastic composition is formed from a 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.