US 11,833,396 B2
Golf ball
Daijiro Kojima, Kobe (JP); Takahiro Sajima, Kobe (JP); and Hikaru Nagakura, Kobe (JP)
Assigned to SUMITOMO RUBBER INDUSTRIES, LTD., Kobe (JP)
Filed by Sumitomo Rubber Industries, Ltd., Kobe (JP)
Filed on Sep. 20, 2022, as Appl. No. 17/948,297.
Claims priority of application No. 2021-153490 (JP), filed on Sep. 21, 2021.
Prior Publication US 2023/0089974 A1, Mar. 23, 2023
Int. Cl. A63B 37/02 (2006.01); A63B 37/00 (2006.01); C08F 279/02 (2006.01)
CPC A63B 37/0051 (2013.01) [A63B 37/0031 (2013.01); A63B 37/0033 (2013.01); A63B 37/0063 (2013.01); A63B 37/0065 (2013.01); A63B 37/0066 (2013.01); A63B 37/0075 (2013.01); A63B 37/00621 (2020.08); A63B 37/00622 (2020.08); C08F 279/02 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A golf ball comprising a spherical core and at least two cover layers covering the spherical core, wherein
the spherical core is formed from a core rubber composition containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator,
a difference (core surface crosslinking density-core center crosslinking density) between a surface crosslinking density of the spherical core and a center crosslinking density of the spherical core is more than 1.0×102 mol/m3 and 7.6×102 mol/m3 or less,
a hardness difference (Cs-Co) between a surface hardness Cs (Shore C hardness) of the spherical core and a center hardness Co (Shore C hardness) of the spherical core is 13.0 or more and 30.0 or less,
a compression deformation amount of the spherical core when applying a load from an initial load of 98 N to a final load of 1275 N to the spherical core is 3.8 mm or more, and
the at least two cover layers include a first cover layer and a second cover layer positioned closer to the spherical core than the first cover layer,
an average hardness Dave=(Ti×Hi+To×Ho)/(Ti+To) of the first cover layer and the second cover layer is 55 or more, where To (mm) is a thickness of the first cover layer, Ho (Shore D) is a slab hardness of the first cover layer, Ti (mm) is a thickness of the second cover layer, and Hi (Shore D) is a slab hardness of the second cover layer.