Solid golf ball

Abstract

A solid golf ball with a polyurethane cover is provided which is satisfactory in the moldability of the cover and in ball characteristics such as a shot feeling and a flight distance. The solid golf ball of the invention includes a solid center, an intermediate layer, and a polyurethane cover. A material having a flexural modulus of from 150 to 420 MPa is used for the intermediate layer in order for the golf ball to offer satisfactory shot feeling and flight distance. By the use of a vulcanizate of a rubber composition containing a diphenyl disulfide for the solid center, the golf ball can exhibit an increased flight distance. In order to enhance the moldability of the cover a urethane prepolymer having a residual isocyanate monomer content of not more than 0.5% by mass is used.

What is claimed is:  
     
         1 . A solid golf ball comprising a solid center, an intermediate layer, and a polyurethane cover, wherein 
 the solid center has an outer diameter of from 36.7 mm to 40.8 mm;    the intermediate layer has a thickness of from 0.5 mm to 1.5 mm and is formed from a material having a flexural modulus of from 150 to 420 MPa; and    the polyurethane cover has a thickness of from 0.5 mm to 1.5 mm and is formed from a cured product of a composition comprising an isocyanate group-terminated urethane prepolymer and an aromatic polyamine compound, the cured product having a Shore D hardness of from 35 to 55.    
     
     
         2 . The solid golf ball according to  claim 1 , wherein the isocyanate group-terminated urethane prepolymer has a residual isocyanate monomer content of not more than 0.5% by mass.  
     
     
         3 . The solid golf ball according to  claim 2 , wherein the isocyanate group-terminated urethane prepolymer has a residual isocyanate monomer content of not more than 0.1% by mass.  
     
     
         4 . The solid golf ball according to  claim 1 , wherein the isocyanate group-terminated urethane prepolymer has an isocyanate component comprising at least one selected from the group consisting of tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and paraphenylene diisocyanate.  
     
     
         5 . The solid golf ball according to  claim 1 , wherein the isocyanate group-terminated urethane prepolymer has an polyol component comprising polyoxytetramethyleneglycol.  
     
     
         6 . The solid golf ball according to  claim 1 , wherein the aromatic polyamine compound is 2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′diaminodiphe nylmethane.  
     
     
         7 . The solid golf ball according to  claim 1 , wherein the solid center has a deformation amount of from 2.8 mm to 3.5 mm when applying a load from 98N as an initial load to 1275 N as a final load, and is formed by vulcanizing a rubber composition which comprises cis-1,4-polybutadiene, an organic peroxide, a co-crosslinking agent, and an organic sulfur compound represented by the general formula:  
       
         
           
           
               
               
           
         
       
       wherein each of X 1  to X 10  is any one selected from the group consisting of a hydrogen atom, a chlorine atom, a bromine atom, an iodine atom, and a cyano group, and X 1  to X 10  are same or different each other.  
     
     
         8 . The solid golf ball according to  claim 7 , wherein the organic sulfur compound is diphenyl disulfide or bis(pentachlorophenyl) disulfide.  
     
     
         9 . The solid golf ball according to  claim 1 , wherein the solid center has the outer diameter of 38 mm to 40 mm.  
     
     
         10 . The solid golf ball according to  claim 1 , wherein the intermediate layer has a thickness of from 0.7 mm to 1.2 mm and is formed from the material having the flexural modulus of from 200 MPa to 400 MPa.  
     
     
         11 . The solid golf ball according to  claim 1 , wherein the polyurethane cover has the thickness of 0.7 mm to 1.3 mm.  
     
     
         12 . The solid golf ball according to  claim 1 , wherein the cured product has the Shore D hardness of from 40 to 52.  
     
     
         13 . The solid golf ball according to  claim 1 , wherein the material having the flexural modulus of from 150 MPa to 420 MPa is an ionomer resin.  
     
     
         14 . A solid golf ball comprising a solid center, an intermediate layer, and a polyurethane cover, wherein 
 the solid center has an outer diameter of from 36.7 mm to 40.8 mm;    the intermediate layer has a thickness of from 0.5 mm to 1.5 mm and is formed from an ionomer resin having a flexural modulus of from 150 MPa to 420 MPa; and    the polyurethane cover has a thickness of from 0.5 mm to 1.5 mm and is formed by curing a polyurethane composition, the cured composition having a Shore D hardness of from 35 to 55, wherein 
 the solid center is formed by vulcanizing a rubber composition which comprises cis-1,4-polybutadiene, an organic peroxide, a co-crosslinking agent, and diphenyl disulfide or bis(pentachlorophenyl) disulfide;  
 the polyurethane cover composition comprises an isocyanate group-terminated urethane prepolymer including tolylenediisocyanate as isocyanate component and polyoxytetramethyleneglycol as polyol component, and an aromatic polyamine compound.  
   
     
     
         15 . The solid golf ball according to  claim 14 , wherein the isocyanate group-terminated urethane prepolymer has a residual isocyanate monomer content of not more than 0.5% by mass.  
     
     
         16 . The solid golf ball according to  claim 15 , wherein the aromatic polyamine compound is 2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diaminodiphenylmethane.