Multi-layered cores having selective weight distribution for golf balls

Abstract

Multi-piece golf balls containing a multi-layered core or a dual-core are provided. The cores have selective weighting configurations (SWC). Particularly, the core layers are made of different compositions having different specific gravity levels or densities. Preferably, rubber and high neutralized ethylene acid copolymer compositions are used to form at least one layer in the core. The rubber and ionomer compositions may be loaded with fillers to adjust the specific gravity levels. The moment of inertia of the ball is adjusted and the resulting ball has good resiliency and spin control properties.

1 . A golf ball, comprising:
 a multi-layer core having i) an inner core having a diameter in the range of about 0.015 to about 0.900 inches and specific gravity in the range of about 1.18 to about 5.00 g/cc (SG inner );
 ii) an intermediate core layer having a thickness in the range of about 0.100 to about 0.600 inches and specific gravity in the range of about 0.080 to about 1.20 g/cc (SG intermediate ); and 
 iii) an outer core layer having a thickness in the range of about 0.010 to about 0.200 inches and specific gravity of about 1.18 to about 5.00 g/cc (SG outer ); so that SG inner  is greater than SG intermediate  and SG intermediate  is less than SG outer ; and 
   
       a cover having at least one layer. 
     
     
         2 . The golf ball of  claim 1 , wherein the weight of the multi-layer core is in the range of about 28 to about 38 grams. 
     
     
         3 . The golf ball of  claim 1 , wherein at least one of the core layers is formed from a rubber composition comprising a rubber material selected from the group consisting of polybutadiene, ethylene-propylene rubber, ethylene-propylene-diene rubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, butyl rubber, halobutyl rubber, polystyrene elastomers, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and mixtures thereof. 
     
     
         4 . The golf ball of  claim 3 , wherein the rubber composition comprises polybutadiene. 
     
     
         5 . The golf ball of  claim 4 , wherein the polybutadiene rubber composition is used to form the intermediate core layer, wherein the layer has a specific gravity in the range of about 1.03 to about 1.18 g/cc. 
     
     
         6 . The golf ball of  claim 1 , wherein at least one of the core layers is formed from an ionomer composition comprising an ethylene acid copolymer containing acid groups such that greater than 70% of the acid groups are neutralized. 
     
     
         7 . The golf ball of  claim 6 , wherein the ionomer composition is used to form the intermediate core layer, wherein the layer has a specific gravity in the range of about 0.93 to about 0.97 g/cc. 
     
     
         8 . The golf ball of  claim 1 , wherein at least one of the core layers comprises high specific gravity filler selected from the group consisting of metal powder, metal alloy powder, metal oxide, metal stearates, particulates, carbonaceous material, and mixtures thereof. 
     
     
         9 . The golf ball of  claim 8 , wherein the high specific gravity filler is selected from the group consisting of bismuth powder, boron powder, brass powder, bronze powder, cobalt powder, copper powder, inconel metal powder, iron metal powder, molybdenum powder, nickel powder, stainless steel powder, titanium metal powder, zirconium oxide powder, aluminum flakes, tungsten metal powder, beryllium metal powder, zinc metal powder, tin metal powder, zinc oxide, iron oxide, aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide and tungsten trioxide. 
     
     
         10 . The golf ball of  claim 1 , wherein the inner core has a diameter in the range of about 0.025 to about 0.080 inches and specific gravity in the range of about 1.20 to about 3.50 g/cc. 
     
     
         11 . The golf ball of  claim 1 , wherein the inner core has a diameter in the range of about 0.030 to about 0.075 inches and specific gravity in the range of about 1.25 to about 3.25 g/cc. 
     
     
         12 . The golf ball of  claim 1 , wherein the intermediate core layer has a diameter in the range of about 0.025 to about 0.080 inches and specific gravity in the range of about 0.090 to about 1.18 g/cc. 
     
     
         13 . The golf ball of  claim 1 , wherein the outer core layer has a thickness in the range of about 0.040 to about 0.170 inches and specific gravity of about 1.10 to about 3.75 g/cc. 
     
     
         14 . The golf ball of  claim 1 , wherein the center of the inner core and surface of the intermediate core layer and surface of the outer core layer each has a hardness, and the surface hardness of the intermediate layer is greater than the center hardness of the inner core and surface hardness of the outer core. 
     
     
         15 . The golf ball of  claim 1 , wherein the center hardness of the inner core is in the range of about 38 Shore D to about 62 Shore D. 
     
     
         16 . The golf ball of  claim 1 , wherein the surface hardness of the intermediate core layer is in the range of about 46 Shore D to about 68 Shore D. 
     
     
         17 . The golf ball of  claim 1 , wherein the surface hardness of the outer core layer is in the range of about 40 Shore D to about 64 Shore D. 
     
     
         18 . The golf ball of  claim 1 , wherein the cover is a single layer having a thickness of about 0.015 to about 0.090 inches and is formed from a thermoplastic or thermoset material. 
     
     
         19 . The golf ball of  claim 1 , wherein the cover comprises two or more layers and has an overall thickness of about 0.020 to about 0.140 inches and wherein each cover layer is formed from a thermoplastic or thermoset material. 
     
     
         20 . The golf ball of  claim 19 , wherein the cover comprises an inner cover layer and outer cover layer, the inner cover having a surface hardness of 60 Shore D or greater and an outer cover layer having a surface hardness in the range of about 20 to about 70 Shore D. 
     
     
         21 . The golf ball of  claim 20 , wherein the inner and outer cover layers are formed from a composition comprising a polymer selected from the group consisting of ethylene acid copolymer ionomers; polyesters; polyamides; polyamide-ethers, polyamide-esters; polyurethanes, polyureas; fluoropolymers; polystyrenes; polypropylenes and polyethylenes; polyvinyl chlorides; polyvinyl acetates; polycarbonates; polyvinyl alcohols; polyethers; polyimides, polyetherketones, polyamideimides; and mixtures thereof. 
     
     
         22 . A golf ball, comprising:
 a dual-core having i) an inner core having a diameter in the range of about 0.015 to about 0.900 inches and specific gravity in the range of about 1.18 to about 5.00 g/cc (SG inner ); and
 ii) an outer core layer having a thickness in the range of about 0.100 to about 0.600 inches and specific gravity in the range of about 0.080 to about 1.20 g/cc (SG outer ) so that SG inner  is greater than SG outer ; and 
   
       a cover having at least one layer. 
     
     
         23 . The golf ball of  claim 22 , wherein the weight of the dual core is in the range of about 28 to about 38 grams. 
     
     
         24 . The golf ball of  claim 22 , wherein at least one of the core layers is formed from a rubber composition comprising a rubber material selected from the group consisting of polybutadiene, ethylene-propylene rubber, ethylene-propylene-diene rubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, butyl rubber, halobutyl rubber, polystyrene elastomers, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and mixtures thereof. 
     
     
         25 . The golf ball of  claim 22 , wherein at least one of the core layers is formed from an ionomer composition comprising an ethylene acid copolymer containing acid groups such that greater than 70% of the acid groups are neutralized.