Golf Balls Containing Multi-Layered Cores With Foam Center and Thermoplastic Outer Layers

Abstract

Golf ball multi-layered core sub-assemblies and the resulting golf balls are provided. The core structure includes a foam inner core (center); and intermediate and outer core layers. Foamed polyurethane is preferably used to make the inner core. The intermediate and outer core layers are preferably made from non-foamed thermoplastic compositions such as ethylene acid copolymer ionomers that are partially or highly neutralized, polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof. The core layers have different hardness and specific gravity levels. The ball further includes a cover having at least one layer. The core structure and resulting ball have relatively good resiliency.

We claim: 
     
         1 . A core assembly for a golf ball, comprising:
 i) an inner core layer comprising a foamed composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches, 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 greater than the H inner core center  to provide a positive hardness gradient;   ii) an intermediate core layer comprising a first non-foamed thermoplastic composition, the composition comprising an elastomer selected from the group consisting of polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof, the intermediate layer being disposed about the inner core and having a thickness in the range of about 0.050 to about 0.400 inches, a specific gravity (SG intermediate ), and an outer surface hardness (H outer surface of IC ) and an inner surface hardness (H inner surface of IC ), the H outer surface of IC  being the same or less than the H inner surface of IC  to provide a zero or negative hardness gradient; and   iii) an outer core layer comprising a second non-foamed thermoplastic composition, the composition comprising an ethylene acid copolymer containing acid groups such that at least 70% of the acid groups are neutralized, the outer core layer being disposed about the intermediate core layer and having a thickness in the range of about 0.100 to about 0.750 inches, a specific gravity (SG outer ), and an outer surface hardness (H outer surface of OC ) and an inner surface hardness (H inner surface of OC ), the H outer surface of OC  being greater than the H inner surface of OC  to provide a positive hardness gradient,   wherein the SG outer , is greater than the SG inner,  and the SG intermediate  is greater than the SG inner .   
     
     
         2 . The core assembly of  claim 1 , wherein the inner core comprises a foamed polyurethane composition. 
     
     
         3 . The core assembly of  claim 2 , wherein the foamed polyurethane composition is prepared by adding water to a mixture of polyisocyanate, polyol, and curing agent compounds, surfactant and catalyst, the water being added in a sufficient amount to cause the mixture to foam. 
     
     
         4 . The core assembly of  claim 1 , wherein the ethylene acid copolymer is an E/X/Y-type copolymer, wherein E is ethylene, 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, and wherein greater than 70% of the acid groups present in the composition are neutralized with a metal ion. 
     
     
         5 . The core assembly of  claim 1 , wherein the inner core has a diameter in the range of about 0.100 to about 0.500 inches and specific gravity in the range of about 0.25 to about 0.95 g/cc. 
     
     
         6 . The core assembly of  claim 1 , wherein the inner core has a diameter in the range of about 0.40 to about 0.80 inches and specific gravity in the range of about 0.30 to about 0.80 g/cc. 
     
     
         7 . The core assembly of  claim 1 , wherein the H inner core center  is in the range of about 10 Shore C or less to about 50 Shore C and the H inner core surface  is in the range of about 15 Shore C to about 60 Shore C. 
     
     
         8 . The core assembly of  claim 1 , wherein the inner surface hardness of the intermediate core (H inner surface of IC ) is in the range of about 35 Shore C to about 96 Shore C, and the outer surface hardness of the intermediate core (H outer surface of IC ) is in the range of about 32 Shore C to and about 93 Shore C. 
     
     
         9 . The core assembly of  claim 1 , wherein the outer core layer has a thickness in the range of about 0.150 to about 0.650 inches and specific gravity in the range of about 0.90 to about 2.90 g/cc. 
     
     
         10 . The core assembly of  claim 1 , wherein the H inner surface of OC  is in the range of about 40 Shore C to about 87 Shore C and the H outer surface of OC  is in the range of about 43 Shore C to about 90 Shore C. 
     
     
         11 . A core assembly for a golf ball, comprising:
 i) an inner core layer comprising a foamed composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches, 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 greater than the H inner core center  to provide a positive hardness gradient;   ii) an intermediate core layer comprising a first non-foamed thermoplastic composition, the composition comprising an elastomer selected from the group consisting of polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof, the intermediate layer being disposed about the inner core and having a thickness in the range of about 0.050 to about 0.400 inches, a specific gravity (SG intermediate ), and an outer surface hardness (H outer surface of IC ) and an inner surface hardness (H inner surface of IC ), the H outer surface of IC  being greater than the H inner surface of IC  to provide a positive hardness gradient; and   iii) an outer core layer comprising a second non-foamed thermoplastic composition, the composition comprising an ethylene acid copolymer containing acid groups such that at least 70% of the acid groups are neutralized, the outer core layer being disposed about the intermediate core layer and having a thickness in the range of about 0.100 to about 0.750 inches, a specific gravity (SG outer ), and an outer surface hardness (H outer surface of OC ) and an inner surface hardness (H inner surface of OC ), the H outer surface of OC  being the same or less than the H inner surface of OC  to provide a zero or negative hardness gradient,   wherein the SG outer , is greater than the SG  inner,  and the SG intermediate  is greater than the SG inner .   
     
     
         12 . The core assembly of  claim 11 , wherein the inner core comprises a foamed polyurethane composition. 
     
     
         13 . The core assembly of  claim 11 , wherein the H inner core center  is in the range of about 10 Shore C to about 50 Shore C and the H inner core surface  is in the range of about 13 Shore C to about 60 Shore C. 
     
     
         14 . The core assembly of  claim 11 , wherein the inner surface hardness of the intermediate core (H inner surface of IC ) is in the range of about 34 Shore C to about 93 Shore C, and the outer surface hardness of the intermediate core (H outer surface of IC ) is in the range of about 37 Shore C to and about 96 Shore C. 
     
     
         15 . The of  claim 11 , wherein the H inner surface of OC  is in the range of about 42 Shore C to about 96 Shore C and the H outer surface of OC  is in the range of about 40 Shore C to about 93 Shore C. 
     
     
         16 . A core assembly for a golf ball, comprising:
 i) an inner core layer comprising a foamed composition, the inner core layer having a diameter in the range of about 0.100 to about 1.100 inches, 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 greater than the H inner core center  to provide a positive hardness gradient;   ii) an intermediate core layer comprising a first non-foamed thermoplastic composition, the composition comprising an elastomer selected from the group consisting of polyester-polyether block copolymers, polyether-amide block copolymers, and blends thereof, the intermediate layer being disposed about the inner core and having a thickness in the range of about 0.050 to about 0.400 inches, a specific gravity (SG intermediate ), and an outer surface hardness (H outer surface of IC ) and an inner surface hardness (H inner surface of IC ), the H outer surface of IC  being the same or less than the H inner surface of IC  to provide a zero or negative hardness gradient; and   iii) an outer core layer comprising a second non-foamed thermoplastic composition, the composition comprising an ethylene acid copolymer containing acid groups such that at least 70% of the acid groups are neutralized, the outer core layer being disposed about the intermediate core layer and having a thickness in the range of about 0.100 to about 0.750 inches, a specific gravity (SG outer ), and an outer surface hardness (H outer surface of OC ) and  an inner surface hardness (H inner surface of OC ), the H outer surface of OC  being the same or less than the H inner surface of OC  to provide a zero or negative hardness gradient, p 1  wherein the SG outer , is greater than the SG inner,  and the SG intermediate  is greater than the SG inner .   
     
     
         17 . The core assembly of  claim 16 , wherein the inner core comprises a foamed polyurethane composition. 
     
     
         18 . The core assembly of  claim 16 , wherein the H inner core center  is in the range of about 10 Shore C to about 50 Shore C and the H inner core surface  is in the range of about 13 Shore C to about 60 Shore C. 
     
     
         19 . The core assembly of  claim 16 , wherein the inner surface hardness of the intermediate core (H inner surface of IC ) is in the range of about 34 Shore C to about 96 Shore C, and the outer surface hardness of the intermediate core (H outer surface of IC ) is in the range of about 30 Shore C to and about 93 Shore C. 
     
     
         20 . The core assembly of  claim 16 , wherein the H inner surface of OC  is in the range of about 42 Shore C to about 96 Shore C and the H outer surface of OC  is in the range of about 40 Shore C to about 93 Shore C.