Thin-layer-covered multilayer golf ball

Abstract

A golf ball includes a core formed of an inner core and at least one outer core layer disposed about the inner core, one of which includes a surface amount of trans-polybutadiene and an interior amount of trans-polybutadiene at least 6 percent less than the surface amount. A cover containing an inner cover layer and an outer cover layer is formed over the core. The inner cover layer includes a block copolymer of styrene and butadiene, isoprene, or ethylene-butylene rubber and has a material hardness of about 60 to 70 Shore D. The outer cover layer is formed from a castable polyurethane or polyurea and having a material hardness of 55 Shore D or less. The inner core has an interior hardness and a surface hardness differing from the interior hardness by greater than 20 percent.

1 . A golf ball comprising:
 a core comprising an inner core and at least one outer core layer disposed about the inner core, at least one of the inner core or the outer core layer comprising a surface amount of trans-polybutadiene and an interior amount of trans-polybutadiene at least 6 percent less than the surface amount; and   a cover comprising an inner cover layer and an outer cover layer, the inner cover layer comprising a block copolymer of styrene and butadiene, isoprene, or ethylene-butylene rubber and having a material hardness of about 60 to 70 Shore D; and the outer cover layer comprising a castable polyurethane or polyurea and having a material hardness of 55 Shore D or less;   wherein the inner core has an interior hardness and a surface hardness differing from the interior hardness by greater than 20 percent.   
   
   
       2 . The golf ball of  claim 1 , wherein the outer cover material hardness is 50 Shore D or less. 
   
   
       3 . The golf ball of  claim 1 , wherein the inner cover layer outer diameter is from 1.59 inches to 1.66 inches. 
   
   
       4 . The golf ball of  claim 3 , wherein the inner cover layer outer diameter is from 1.6 inches to 1.64 inches. 
   
   
       5 . The golf ball of  claim 1 , wherein the inner core has an outer diameter of about 0.5 inches to 1.25 inches. 
   
   
       6 . The golf ball of  claim 5 , wherein the inner core outer diameter is about 0.9 inches to 1.2 inches. 
   
   
       7 . The golf ball of  claim 1 , wherein the outer core layer has an outer diameter of about 1.52 inches to 1.59 inches. 
   
   
       8 . The golf ball of  claim 7 , wherein the outer core layer outer diameter is about 1.535 inches to 1.58 inches. 
   
   
       9 . A golf ball comprising:
 a core comprising an inner core and at least one outer core layer disposed about the inner core, at least one of the inner core or outer core layer comprises a thermosetting rubber composition comprising a trans-polybutadiene infrared peak between 600 cm −1  and 1100 cm −1  such that an area under the trans-polybutadiene infrared peak is at least 5 to 70 percent of a total area of cis-, trans-, and vinyl-polybutadiene infrared peaks; and   a cover comprising an inner cover layer and an outer cover layer, the inner cover layer comprising a thermosetting or thermoplastic material and having a material hardness of about 60 to 70 Shore D; and the outer cover layer comprising a castable polyurethane or polyurea material and having a material hardness of 55 Shore D or less.   
   
   
       10 . The golf ball of  claim 1 , wherein the inner core is solid.