GOLF BALL HAVING MEDIUM POSITIVE GRADIENT QUOTIENT
A golf ball includes a core and a cover. The core has an outer surface, a geometric center, and a soft transition region adjacent to the outer surface. The soft transition region has a thickness of 4 mm or less, includes about 10 to 30% trans-polybutadiene isomer, and has a positive hardness gradient of about 10 Shore C or less. The cover layer has a hardness of about 50 Shore M or greater. The core has a positive hardness gradient of about 10 to 42 Shore C. A secondary gradient quotient, GQ′, from about 2.2 to 9.5, GQ′ being defined by the equation: G ′ + T 10 × COR where G′ is the core positive hardness gradient in Shore C, T is the percent of trans-polybutadiene isomer at the core outer surface, and COR is the coefficient of restitution of the core measured at an incoming velocity of 125 ft/s.
1 . A golf ball comprising:
a core having an outer surface, a geometric center, and a soft transition region adjacent to the outer surface, the soft transition region having a thickness of about 4 mm or less, comprises about 10 to 30 percent of a trans-polybutadiene isomer, and has a first positive hardness gradient of about 10 Shore C or less; and
an outer cover layer having a hardness of about 50 Shore M or greater;
wherein the core has an outer surface hardness greater than a hardness at the geometric center to define a second positive hardness gradient of about 10 Shore C to 42 Shore C; and a secondary gradient quotient, GQ′, from about 2.2 to 9.5, GQ′ being defined by the equation:
G
′
+
T
10
×
COR
where G′ is the core positive hardness gradient in Shore C, T is the percent of trans-polybutadiene isomer at the core outer surface, and COR is the coefficient of restitution of the core measured at an incoming velocity of 125 ft/s.
2 . The golf ball of claim 1 , wherein the second positive hardness gradient is about 12 Shore C to 35 Shore C.
3 . The golf ball of claim 2 , wherein the second positive hardness gradient is about 13 Shore C to 24 Shore C.
4 . The golf ball of claim 3 , wherein the second positive hardness gradient is about 14 Shore C to 21 Shore C.
5 . The golf ball of claim 1 , wherein the core has a COR of about 0.800 or greater.
6 . The golf ball of claim 5 , wherein the COR is about 0.810 or greater.
7 . The golf ball of claim 1 , wherein the secondary gradient quotient, GQ′, is about 2.5 to 8.5 and the second positive hardness gradient is about 12 Shore C to about 35 Shore C.
8 . The golf ball of claim 7 , wherein the secondary gradient quotient, GQ′, is about 2.7 to 6.9 and the second positive hardness gradient is about 13 Shore C to about 24 Shore C.
9 . The golf ball of claim 8 , wherein the secondary gradient quotient, GQ′, is about 2.9 to 6.5 and the second positive hardness gradient is about 14 Shore C to about 21 Shore C.
10 . The golf ball of claim 1 , wherein the golf ball comprises an inner cover layer comprising an ionomer.
11 . The golf ball of claim 10 , wherein the ionomer comprises a lithium ionomer or a sodium ionomer.
12 . The golf ball of claim 1 , wherein the golf ball comprises an outer core layer disposed about the core.
13 . The golf ball of claim 1 , wherein the golf ball comprises at least one coating layer disposed about the cover layer.
14 . The golf ball of claim 13 , wherein the coating layer has a Shore M hardness of about 60 Shore M or less.
15 . The golf ball of claim 13 , wherein the coating layer has an instrumented hardness of about 1 to 23 MPa.
16 . The golf ball of claim 13 , wherein the coating layer has a thickness of about 0.001 inches to about 0.003 inches.
17 . The golf ball of claim 1 , wherein the soft transition region comprises about 10 to 20 percent trans-polybutadiene isomer.
18 . The golf ball of claim 1 , wherein the soft transition region comprises about 20 to 30 percent trans-polybutadiene isomer.
19 . A golf ball comprising:
a core having an outer surface, a geometric center, and a soft transition region adjacent to the outer surface, the soft transition region having a thickness of about 4 mm or less, comprises about 10 to 30 percent of a trans-polybutadiene isomer, and has a positive hardness gradient of about 10 Shore C or less; and
an outer cover layer having a hardness of about 50 Shore M or greater;
wherein the core has an outer surface hardness greater than a hardness at the geometric center to define a positive hardness gradient of about 12 Shore C to 24 Shore C; and a secondary gradient quotient, GQ′, from about 7.5 to 9.5, GQ′ being defined by the equation:
G
′
+
T
10
×
COR
where G′ is the core positive hardness gradient in Shore C, T is the percent of trans-polybutadiene isomer at the core outer surface, and COR is the coefficient of restitution of the core measured at an incoming velocity of 125 ft/s.