US 11,938,380 B2
Golf balls having cores with increased hardness gradient
Erin McDermott, Providence, RI (US); Manjari Kuntimaddi, Raynham, MA (US); and Dennis Britton, North Dartmouth, MA (US)
Assigned to Acushnet Company, Fairhaven, MA (US)
Filed by Acushnet Company, Fairhaven, MA (US)
Filed on Jun. 14, 2022, as Appl. No. 17/839,654.
Prior Publication US 2023/0398413 A1, Dec. 14, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. A63B 37/06 (2006.01); A63B 37/00 (2006.01)
CPC A63B 37/00921 (2020.08) [A63B 37/0032 (2013.01); A63B 37/0033 (2013.01); A63B 37/0039 (2013.01); A63B 37/0045 (2013.01); A63B 37/0063 (2013.01); A63B 37/0075 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A golf ball, comprising:
a solid core having an outer surface and a geometric center, wherein the solid core is formed from a rubber composition cured under heat, the rubber composition comprising:
a base rubber consisting of polybutadiene rubber,
an organic peroxide,
a cross-linking co-agent comprising a zinc salt of an acrylate, diacrylate, methacrylate, or dimethacrylate,
calcium sulfate dihydrate present in the rubber composition in an amount of about 1 phr to about 3.9 phr,
wherein the geometric center and the outer surface each has a hardness and the hardness of the geometric center ranges from about 45 Shore C to about 65 Shore C and the hardness of the outer surface ranges from about 80 Shore C to about 100 Shore C, and
wherein the hardness of the outer surface is greater than the hardness of the geometric center to define a positive hardness gradient of at least 30 Shore C units; and
a cover layer surrounding the solid core, wherein the cover layer comprises an ionomer, polyurethanes, polyureas, polyurethane-urea hybrids, or copolymers and blends thereof.