US 12,390,694 B2
Multi-piece solid golf ball
Hideo Watanabe, Saitamaken (JP)
Assigned to BRIDGESTONE SPORTS CO., LTD., Tokyo (JP)
Filed by Bridgestone Sports Co., Ltd., Tokyo (JP)
Filed on Jul. 19, 2023, as Appl. No. 18/355,094.
Claims priority of application No. 2022-141169 (JP), filed on Sep. 6, 2022.
Prior Publication US 2024/0075349 A1, Mar. 7, 2024
Int. Cl. A63B 37/06 (2006.01); A63B 37/00 (2006.01); C08L 9/06 (2006.01)
CPC A63B 37/0075 (2013.01) [A63B 37/0063 (2013.01); A63B 37/0065 (2013.01); A63B 37/0084 (2013.01); A63B 37/00922 (2020.08); C08L 9/06 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A multi-piece solid golf ball comprising a core, an intermediate layer and a cover, wherein the sphere obtained by encasing the core with the intermediate layer has a surface hardness and the ball has a surface hardness which together satisfy the following condition:
(surface hardness of ball)<(surface hardness of intermediate layer-encased sphere);
the ball has an initial velocity of not more than 75.0 m/s; and the core has a hardness profile such that, letting Cc be the Shore C hardness at a center of the core, Cs be the Shore C hardness at a surface of the core, Cm be the Shore C hardness at a midpoint M between the core center and the core surface, Cm−2, Cm−4 and Cm−6 be the respective Shore C hardnesses at positions 2 mm, 4 mm and 6 mm inward from the midpoint M and Cm+2, Cm+4 and Cm+6 be the respective Shore C hardnesses at positions 2 mm, 4 mm and 6 mm outward from the midpoint M and defining surface areas A to F as follows
surface area A:½×2×(Cm−4−Cm−6)
surface area B:½×2×(Cm−2−Cm−4)
surface area C:½×2×(Cm−Cm−2)
surface area D:½×2×(Cm+2−Cm)
surface area E:½×2×(Cm+4−Cm+2)
surface area F:½×2×(Cm+6−Cm+4),
the core satisfies the condition:
{(surface area C+surface area D)−(surface area A+surface area B)}×(Cs−Cc)≥30,
and wherein the core is formed of a rubber composition comprising:
(A) a base rubber consisting of from 50 to 100 wt % of a styrene butadiene rubber and from 0 to 50 wt % of another diene rubber,
(B) a co-crosslinking agent including zinc acrylate,
(C) water or a metal monocarboxylate, and
(D) an organic peroxide.