MEDIUM GRADIENT MULTI-PIECE URETHANE COVERED GOLF BALL
A golf ball includes a core having an outer surface and a geometric center; an inner cover layer, and an outer cover layer. The inner cover layer includes an ionomeric material and has a material hardness of about 60 Shore D or greater. The outer cover layer is formed from a polyurea or polyurethane and has a material hardness of about 60 Shore M or greater. The outer surface of the core has a hardness of about 68 to 92 Shore C. The geometric center of the core has a hardness of about 45 to 85 Shore C. The core outer surface hardness is greater than the geometric center hardness by about 5 to 21 Shore C to define a positive hardness gradient. The core also has a volume weighted average hardness, H V , of about 70 to 80, where H _ V = I V V c .
1 . A golf ball comprising:
a core having a first outer surface and a geometric center;
an inner cover layer, the inner cover layer comprising an ionomeric material and having a material hardness of about 60 Shore D or greater; and
an outer cover layer, the outer cover layer comprising a polyurea or a polyurethane and having a material hardness of about 60 Shore M or greater;
wherein the first outer surface has a hardness of about 68 to 92 Shore C, the geometric center has a hardness of about 45 to 85 Shore C, and the core has a positive hardness gradient of about 5 to 21 Shore C and a volume weighted average hardness, H V , of about 70 to 80, where
H
_
V
=
I
V
V
c
.
2 . The golf ball of claim 1 , wherein the volume weighted average hardness, H V , of about 70 to 75, where
H
_
V
=
I
V
V
c
.
3 . The golf ball of claim 2 , wherein the volume weighted average hardness, H V , of about 73 to 75, where
H
_
V
=
I
V
V
c
.
4 . The golf ball of claim 1 , wherein the positive hardness gradient is about 11 to 19 Shore C.
5 . The golf ball of claim 4 , wherein the positive hardness gradient is about 13 to 18 Shore C.
6 . The golf ball of claim 1 , wherein the core has an outer diameter of about 1.45 to about 1.62 inches.
7 . The golf ball of claim 1 , wherein the hardness of the geometric center is about 60 to 85 Shore C.
8 . The golf ball of claim 1 , wherein the hardness of the first outer surface is about 74 to 88 Shore C.
9 . The golf ball of claim 8 , wherein the first outer surface hardness is about 80 to 86 Shore C.
10 . The golf ball of claim 1 , wherein the outer cover layer comprises a coating layer having a Shore M hardness of about 60 or less.
11 . The golf ball of claim 10 , wherein the coating layer has a Shore M hardness of about 50 or less.
12 . The golf ball of claim 10 , wherein the coating layer has an instrumented hardness of about 0.1 MPa to about 23 MPa.
13 . The golf ball of claim 1 , wherein the golf ball comprises an outer core layer disposed between the core and the inner cover layer.