Golf ball

Abstract

In a golf ball having a core, a cover and a coating layer, the coating layer is formed of a urethane coating that includes an organic solvent having a boiling point of 80° C. or less, a silicone-based additive and, as a curing agent, a polyisocyanate which contains an adduct and an isocyanurate of hexamethylene diisocyanate. Although the golf ball includes a silicone-based additive in the outer surface (coating layer) of the ball, it has a good spin performance on approach shots not only when wet but also when normally dry, and is capable of exhibiting both a good water-repelling performance and a good friction performance.

1 . A golf ball comprising a core, a cover and a coating layer, wherein the coating layer is formed of a urethane coating comprised of an organic solvent having a boiling point of 80° C. or less, a silicone-based additive and, as a curing agent, a polyisocyanate which includes an adduct and an isocyanurate of hexamethylene diisocyanate (HMDI). 
     
     
         2 . The golf ball of  claim 1 , wherein the organic solvent having a boiling point of 80° C. or less is included in a proportion, based on the overall amount of the coating composition, of at least 20 wt %. 
     
     
         3 . The golf ball of  claim 1 , wherein the mixing ratio by weight (A)/(B) between the isocyanurate (A) and the adduct (B) of hexamethylene diisocyanate is from 85/15 to 15/85. 
     
     
         4 . The golf ball of  claim 1 , wherein at least one layer of the cover is formed of a resin composition comprising:
 (I) a polyurethane or a polyurea, and   (II) an aromatic vinyl elastomer, which aromatic vinyl elastomer has a Shore D hardness of 30 or less and a rebound resilience of 30% or less.   
     
     
         5 . The golf ball of  claim 4 , wherein the content of component (II) is from 5 to 20 parts by weight per 100 parts by weight of component (I). 
     
     
         6 . The golf ball of  claim 4 , wherein the resin composition further comprises (III) a thermoplastic polyester elastomer having a Shore D hardness of 45 or less, a rebound resilience of 74% or less, and a melt viscosity at 200° C. and a shear rate of 243 sec −1  of 1.5×10 4  dPa·s or less. 
     
     
         7 . The golf ball of  claim 1  wherein, when the ball is allowed to fall freely onto an impact surface inclined 58° to the horizontal from a height position 3 m above the surface, the amount of sliding by the ball, designated as “Ds” and defined as the perpendicular displacement by the ball from where sliding of the ball on the impact surface begins to where sliding ends, is 2.0 mm or less, and the contact time of the ball after sliding, designated as “Tc” and defined as the time from when sliding of the ball on the impact surface ends until the ball separates from the impact surface, is at least 400 μs.