Patent ID: 11938380
Assignee: ACUSHNET COMPANY
Field: Furniture, games (Other fields)
Classification: CPC A | IPC A

Claim 5:
6. 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 having a 1,4 cis-bond content of at least 90 percent,
an organic peroxide,
zinc diacrylate,
calcium sulfate dihydrate present in the rubber composition in an amount of about 1 phr to about 3.9 phr,
an additive selected from zinc pentachlorothiophenol, zinc oxide, barium sulfate, or combinations thereof,
wherein the geometric center and the outer surface each has a hardness and the hardness of the geometric center ranges from about 40 Shore C to about 70 Shore C and the hardness of the outer surface ranges from about 75 Shore C to about 105 Shore C,

wherein the hardness of the outer surface is greater than the hardness of the geometric center to define a positive hardness gradient of 30 Shore C units to 50 Shore C units,
wherein the amount of calcium sulfate dihydrate and the number of waters of hydration are related to the positive hardness gradient, according to equation (I):, 2
     ≤
     
      
       
        WRA
        C
       
       *
       
        WRA
        WOH
       
      
      
       1
       -
       
        1
        
         H
         Gr
        
       
      
     
     ≤
     15
    
   
   
    
     (
     I
     ), where WRAC represents the amount of calcium sulfate dihydrate in parts per hundred; HGr represents the positive hardness gradient (Shore C); and WRAWOH represents the number of waters of hydration in the calcium sulfate dihydrate;
an inner cover layer surrounding the core, wherein the inner cover layer is formed of an ionomer; and
an outer cover layer disposed about the inner cover layer, wherein the outer cover layer is formed of a polymer selected from the group consisting of polyurethanes, polyureas, polyurethane-urea hybrids, and copolymers and blends thereof.