Method for forming a golf ball and resulting golf ball

Abstract

A pre-molded dimple-free golf ball is formed before dimples are created in a thermoplastic cover of the pre-molded dimple-free golf ball.

1 . A method of forming a golf ball comprising the steps of:
 forming a subassembly comprising a core;   forming a pre-molded dimple-free golf ball by compression molding a thermoplastic cover comprised of first and second pre-formed thermoplastic half-shells about the subassembly using a pair of mold cavities having inner surfaces that are configured to form a smooth outer surface on the thermoplastic cover at a pre-molding temperature Tdf;   providing a compression mold press having at least one pair of mold cavities wherein each of a top mold cavity and a bottom mold cavity of the pair is configured to form a predetermined dimple pattern on the outer surface of the pre-molded dimple-free golf ball;   depositing the pre-molded dimple free-golf ball into the bottom mold cavity;   closing said top mold cavity and bottom mold cavity about the pre-molded dimple-free golf ball such that an inner surface of each of the top mold cavity and bottom mold cavity having the predetermined dimple pattern therein contacts the dimple-free outer surface of the pre-molded golf ball under contact pressure at a first temperature followed by applying a molding cycle to the closed top mold cavity and bottom mold cavity at a dimpling temperature Tcm sufficient to form a dimpled golf ball wherein an outer surface of the thermoplastic cover is re-solidified and contains the predetermined dimple pattern;   wherein the dimpling temperature Tcm is lower than the pre-molding temperature Tdf; and the first temperature is lower than each of the pre-molding temperature Tdf and the dimpling temperature Tcm.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The method of  claim 1 , wherein the thermoplastic cover comprises at least one thermoplastic polyurethane. 
     
     
         5 . The method of  claim 1 , wherein the subassembly further comprises an outermost layer that is disposed between the core and the thermoplastic cover; wherein the outermost layer comprises an ionomer composition. 
     
     
         6 . The method of  claim 1 , wherein the core comprises an inner core surrounded by an outer core layer. 
     
     
         7 . The method of  claim 1 , wherein the pre-molded dimple-free golf ball has a diameter of greater than 1.68 inches. 
     
     
         8 . The method of  claim 7 , wherein the pre-molded dimple-free golf ball has a diameter of greater than 1.70 inches. 
     
     
         9 . The method of  claim 1 , wherein the thermoplastic cover has a thickness of from about 0.025 inches to about 0.045 inches. 
     
     
         10 . The method of  claim 1 , wherein Tcm is less than Tdf by at least 40° F. 
     
     
         11 . The method of  claim 10 , wherein Tcm is less than Tdf by from about 90° F. to about 170° F. 
     
     
         12 . The method of  claim 10 , wherein Tcm is less than Tdf by from about 120° F. to about 170° F. 
     
     
         13 . The method of  claim 1 , wherein Tcm is applied for a duration of from about 1 minute to about 3 minutes. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . A golf ball made according to the method of  claim 1 , wherein the subassembly further comprises an outermost layer that is disposed between the core and the thermoplastic cover; wherein the outermost layer comprises an ionomer composition. 
     
     
         17 . The golf ball of  claim 16 , wherein the core comprises an inner core surrounded by an outer core layer. 
     
     
         18 . The golf ball of  claim 16 , wherein the golf ball has a diameter of from about 1.68 inches to 1.70 inches; the core has a diameter of from about 1.530 inches to 1.560 inches; and the subassembly has a diameter of from about 1.610 inches to 1.640 inches. 
     
     
         19 . The method of  claim 1 , wherein the dimpling temperature Tcm is from about 280° F. to 380° F. and less than the pre-molding temperature Tdf by at least 40° F.; and wherein the pre-molding temperature Tdf is greater than the first temperature by at least 70° F. 
     
     
         20 . The method of  claim 1 , wherein pre-molding temperature Tdf is less than 440° F. and the dimpling temperature Tcm is lower than the pre-molding temperature Tdf by from about 60° F. to about 160° F.; and wherein the pre-molding temperature Tdf is greater than the first temperature by at least 70° F. 
     
     
         21 . The method of  claim 1 , wherein the dimpling temperature Tcm is lower than the pre-molding temperature Tdf by from about 120° F. to about 170° F. and the pre-molding temperature Tdf is greater than the first temperature by at least 70° F. 
     
     
         22 . The method of  claim 1 , wherein pre-molding temperature Tdf is 380° F.-450° F. and the dimpling temperature Tcm is lower than the pre-molding temperature Tdf by from about 90° F. to less than about 120° F.; and wherein the pre-molding temperature Tdf is greater than the first temperature by at least 100° F.