Golf balls having a core with surrounding intermediate foam layer
Multi-layered golf balls having a core, intermediate layer, and cover are provided. The ball includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An intermediate layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. The foamed intermediate layer may have a specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. Ball constructions having two intermediate layers, wherein at least one layer is a foamed layer can be made. A cover having at least one layer is disposed about the intermediate layer.
1. A multi-layered golf ball, comprising:
i) an inner core comprising a non-foamed thermoset or thermoplastic composition, the inner core having a specific gravity (SG inner ) and an outer surface hardness (H inner core surface ) and a center hardness (H inner core center ), the H inner core surface being the same or less than the H innercore center to provide a zero or negative hardness gradient;
ii) an intermediate layer comprising a foamed thermoset composition, the intermediate layer being disposed about the core, the intermediate layer having a specific gravity (SG intermed. ) and an outer surface hardness (H outer surface of intermed. ) and a midpoint hardness (H midpoint of intermed. ), the H outer surface of intermed. being greater than the H midpoint of intermed. , to provide a positive hardness gradient; wherein the SG inner is greater than the SG intermed. , the intermediate layer further having a specific gravity gradient, wherein the intermediate layer has an outer surface specific gravity and a midpoint specific gravity, the outer surface specific gravity being greater than the midpoint specific gravity; and
iii) a cover having at least one layer disposed about the intermediate layer.
2. The golf ball of claim 1 , wherein the H inner core center is in the range of about 31 to about 95 Shore C and the H innercore surface is in the range of about 30 to about 90 Shore C.
3. The golf ball of claim 1 , wherein the (H midpoint of intermed. ) is in the range of about 10 to about 55 Shore C and the H outer surface of intermed. is in the range of about 11 to about 60 Shore C.
4. The golf ball of claim 1 , wherein the inner core comprises a thermoset rubber selected from the group consisting of polybutadiene, ethylene-propylene rubber, ethylene-propylene-diene rubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, and butyl rubber, and mixtures thereof.
5. The golf ball of claim 1 , wherein the inner core comprises a thermoplastic polymer 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.