Golf ball

Abstract

A golf ball ( 1 ) comprises a center ( 2 ), a rubber thread layer ( 3 ) and a cover ( 4 ). The rubber thread layer ( 3 ) is formed by winding a drawn rubber thread around the center ( 2 ). The rubber thread is obtained by cutting a crosslinked rubber sheet. A hysteresis loss of the crosslinked rubber sheet is 30% or less with an extension range of 0% to 1000%. Moreover, a universal hardness of a DIN standard measured with a load of 3 mN is 1.5 N/mm 2 to 5 N/mm 2 when a whole length is increased up to 1000%. The rubber thread is broken with difficulty during drawing. The golf ball ( 1 ) has an excellent resilience performance.

What is claimed is:  
     
         1 . A golf ball comprising: 
 a center;    a rubber thread layer formed by winding a rubber thread around the center; and    a cover,    wherein the rubber thread is formed of a material in which a hysteresis loss is 30% or less with an extension ratio of 0% to 1000% and a universal hardness of a DIN standard measured with a load of 3 mN is 1.5 N/mm 2  to 5 N/mm 2  when a whole length is increased up to 1000%.    
     
     
         2 . The golf ball according to  claim 1 , wherein a base rubber of the rubber thread contains synthetic polyisoprene and a ratio of the synthetic polyisoprene to the whole base rubber is 70% by weight or more.  
     
     
         3 . The golf ball according to  claim 2 , wherein a ratio of trans 1, 4 bond in the synthetic polyisoprene is 2% or more.  
     
     
         4 . The golf ball according to  claim 1 , wherein the rubber thread is crosslinked with sulfur and a vulcanization accelerator and a weight ratio of the sulfur to the vulcanization accelerator is 0.8/1 to 8/1.  
     
     
         5 . The golf ball according to  claim 1 , wherein a crosslinking density of polysulfide bond of the rubber thread is 1×10 −8  mol/mm 3  to 3×10 −8  mol/mm 3 .