Golf balls having non-uniform core structures with metal-containing centers
Multi-piece golf balls having a solid core and cover are provided. The ball contains a small, heavy inner core and surrounding outer core layer. The inner core preferably contains metal materials such as copper, steel, brass, tungsten, titanium, nickel, iron, tin, and bronze particles dispersed in a thermoset or thermoplastic polymeric matrix. Preferably, the polymeric matrix comprises polybutadiene rubber. The outer surface of the inner core preferably has a non-uniform structure and includes projecting members. For example, the outer surface may contain multiple projecting ribs with gaps located between the ribs. The ball includes a cover surrounding the core structure. The cover may be multi-layered.
1. A multi-layered golf ball, comprising:
i) an inner core comprising a metal material dispersed in a thermoset or thermoplastic polymeric matrix, the inner core having a center and outer surface, and a diameter in the range of about 0.100 to about 1.100 inches, the inner core having projecting members on the outer surface;
ii) an outer core layer comprising a thermoset or thermoplastic material, the outer core layer being disposed about the inner core and having a thickness in the range of about 0.200 to about 0.800 inches, wherein the inner core has a specific gravity (SG inner ) and a center hardness (H inner core center ), and the outer core has a specific gravity (SG outer ) and an outer surface hardness ((H outer surface of OC ), the SG inner being greater than the SG outer , and the H inner core center being in the range of about 10 to about 80 Shore C and the H outer surface of OC being in the range of about 65 to about 96 Shore C to provide a positive hardness gradient across the core assembly; and
iii) a cover having at least one layer disposed about the multi-layered core.
2. The golf ball of claim 1 , wherein the inner core comprises a metal dispersed in a thermoset polymeric matrix, the thermoset polymer being selected from selected from the group consisting of polybutadiene rubber, 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.
3. The golf ball of claim 2 , wherein the thermoset polymer is polybutadiene rubber.
4. The golf ball of claim 3 , wherein the thermoset polymeric matrix has a concentration of polybutadiene rubber of at least 40% by weight.
5. The golf ball of claim 3 , wherein the thermoset polymeric matrix is prepared from a composition further comprising a peroxide free-radical initiator and reactive cross-linking co-agent.
6. The golf ball of claim 5 , wherein the peroxide free-radical initiator is dicumyl peroxide and the reactive cross-linking co-agent is zinc diacrylate.
7. The golf ball of claim 1 , wherein the metal material of the inner core is a metal selected from the group consisting of copper, steel, brass, tungsten, titanium, aluminum, magnesium, molybdenum, cobalt, nickel, iron, tin, bronze, silver, gold, and platinum, and oxides, and alloys and combinations thereof.
8. The golf ball of claim 1 , wherein the projecting members are spaced apart from each other and gaps are located between the projections.
9. The golf ball of claim 8 , wherein the projecting members are shaped and positioned so that the inner core has a substantially spherical shape.
10. The golf ball of claim 8 , wherein the outer core layer is disposed about the inner core such that the material of the outer core layer fills the gaps between the projecting members.
11. The golf ball of claim 1 , wherein the inner core comprises a metal dispersed in a thermoplastic polymeric matrix, the thermoplastic polymer being selected from selected from the group consisting of partially-neutralized ionomers; highly-neutralized ionomers; polyesters; polyamides; polyamide-ethers, polyamide-esters; polyurethanes, polyureas; fluoropolymers; polystyrenes; polypropylenes; polyethylenes; polyvinyl chlorides; polyvinyl acetates; polycarbonates; polyvinyl alcohols; polyester-ethers; polyethers; polyimides, polyetherketones, polyamideimides; and mixtures thereof.
12. The golf ball of claim 11 , wherein the thermoplastic material is an ionomer composition comprising an O/X/Y-type copolymer, wherein O is α-olefin, X is a C 3 -C 8 α,β-ethylenically unsaturated carboxylic acid present in an amount of 10 to 20 wt. %, based on total weight of the copolymer, and Y is an acrylate selected from alkyl acrylates and aryl acrylates present in an amount of 0 to 50 wt. %, based on total weight of the copolymer, wherein greater than 70% of the acid groups present in the composition are neutralized with a metal ion.