GOLF BALL CORE WITH TAILORED HARDNESS GRADIENT
Compositions including a hardness agent and golf ball cores made from such compositions having a tailored hardness gradient are disclosed. The type and concentration of the components in the composition, including the hardness agent, affects the hardness, hardness gradient, and compression of cores made from the composition and, thus, can be used to produce a golf ball having desirable performance characteristics.
1 . A golf ball, comprising:
a core formed from a rubber formulation comprising a base rubber and a hardening agent including a first functional group and a second functional group, wherein the hardening agent has a hardening agent concentration HA C and a hardening agent isomer number HA LN , wherein the core has a hardness gradient H Gr equal to the difference between a geometric center hardness H C and a surface hardness H S , and wherein
H
A
C
*
H
A
LN
H
Gr
0
.
2
≥
0
.25
;
and
a cover layer disposed about the core.
2 . The golf ball of claim 1 , wherein the first functional group is meta or para to the second functional group.
3 . The golf ball of claim 1 , wherein the first functional group is ortho to the second functional group.
4 . The golf ball of claim 1 , wherein the first functional group comprises a nitro functional group, and wherein the second functional group comprises at least one of a hydroxyl, amino, or sulfhydryl functional group.
5 . The golf ball of claim 1 , wherein the hardening agent is present in an amount of about 0.05 to about 3.0 parts per hundred rubber.
6 . The golf ball of claim 1 , wherein H Gr ≥2.
7 . The golf ball of claim 1 , wherein
0
.
2
5
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
0
.
3
5
.
8 . The golf ball of claim 1 , wherein
0.8
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
0
.
9
.
9 . The golf ball of claim 1 , wherein
1.2
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
1
.
4
.
10 . A golf ball, comprising:
a core formed from a rubber formulation comprising a base rubber and a hardening agent including a first functional group and a second functional group, wherein the hardening agent has a hardening agent concentration HA C and a hardening agent isomer number HA LN , wherein the core has a hardness gradient H Gr equal to the difference between a geometric center hardness H C and a surface hardness H S , wherein H Gr is between 2 Shore C and 42 Shore C, and wherein
H
A
C
*
H
A
LN
H
Gr
0
.
2
≥
0
.25
;
and
a cover layer disposed about the core.
11 . The golf ball of claim 10 , wherein the first functional group comprises a nitro functional group, and wherein the second functional group comprises at least one of a hydroxyl, amino, or sulfhydryl functional group.
12 . The golf ball of claim 11 , wherein the first functional group is meta or para to the second functional group.
13 . The golf ball of claim 11 , wherein the first functional group is ortho to the second functional group.
14 . The golf ball of claim 10 , wherein
0
.
2
5
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
0
.
3
5
.
15 . The golf ball of claim 10 , wherein
0.8
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
0
.
9
.
16 . The golf ball of claim 10 , wherein
1.2
≤
H
A
C
*
H
A
LN
H
Gr
0
.
2
≤
1
.
4
.
17 . A golf ball, comprising:
a core formed from a rubber formulation comprising a base rubber and a hardening agent including a first functional group and a second functional group, wherein the first functional group is meta or para to the second functional group, wherein the hardening agent has a hardening agent concentration HA C and a hardening agent isomer number HA LN , wherein the core has a hardness gradient H Gr equal to the difference between a geometric center hardness H C and a surface hardness H S , wherein H Gr ≥2, and wherein
H
A
C
*
H
A
LN
H
Gr
0
.
2
≥
0
.25
;
and
a cover layer disposed about the core.
18 . The golf ball of claim 17 , wherein the hardening agent is present in an amount of about 0.05 and about 3.0 parts per hundred rubber.
19 . The golf ball of claim 18 , wherein the hardening agent is present in an amount of about 0.4 and about 0.6 parts per hundred rubber.
20 . The golf ball of claim 17 , wherein the first functional group comprises a nitro functional group, and wherein the second functional group comprises at least one of a hydroxyl, amino, or sulfhydryl functional group.