Solid golf ball

Abstract

Disclosed is a solid golf ball containing at least one rubber portion formed from a rubber composition comprising a base rubber, a co-crosslinking agent and an organic peroxide; an improvement being present in that the base rubber is a mixture of (A) a solid polybutadiene rubber containing cis-1,4 bonds in an amount of at least 40%, and (B) either a liquid polybutadiene rubber or a liquid isoprene-butadiene copolymer rubber, or both.

What is claimed is: 
     
       1. A solid golf ball containing at least one rubber portion formed from a rubber composition comprising a base rubber, a co-crosslinking agent and an organic peroxide; an improvement being present in that said base rubber is a mixture of (A) a solid polybutadiene rubber containing cis -1,4 bonds in an amount of at least 40%, and having a Moooney viscosity (ML 1+4  100° C. ) of .[.45.]. .Iadd.43 .Iaddend.to 90 and a ratio of weight average molecular weight/number average molecular weight (Mx/Mn) of 4.0 or less; and   (B) either a liquid polybutadiene rubber or a liquid isoprene-butadiene copolymer rubber, or both.   
     
     
       2. The solid golf ball according to claim 1 wherein said liquid rubber component (B) has a number average molecular weight of 1,000 to 50,000. 
     
     
       3. The solid golf ball according to claim 1 wherein said liquid rubber component (B) does not have carboxyl groups at the terminals of the molecule. 
     
     
       4. The solid golf ball according to claim 1 wherein a weight ratio of polybutadiene component (A)/liquid rubber component (B) is within the range of 98/2 to 72/25. 
     
     
       5. The solid golf ball according to claim 1 wherein said co-crosslinking agent is acrylic acid, methacrylic acid or a divalent metal salt thereof. 
     
     
       6. The solid golf ball according to claim 1 wherein an amount of the co-crosslinking agent is within in the range of 15 to 60 parts by weight based on 100 parts by weight of the base rubber. 
     
     
       7. The solid golf ball according to claim 1 wherein said organic peroxide includes dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2, 5-di(t-butylperoxy)hexane or di-t-butylperoxide. 
     
     
       8. The solid golf ball according to claim 1 wherein said organic peroxide is present in the rubber composition in an amount of 0.3 to 3.0 parts by weight based on 100 parts by weight of the base rubber.