Thermoplastic multi-layer golf ball

Abstract

A thermoplastic multi-layer golf ball has a core center including a first thermoplastic material and having a diameter of from about 7 mm to about 20 mm and a surface Shore D hardness H1 of from about 30 to about 48; a core layer outward from the core center, the core layer including a second thermoplastic material and having a diameter of from about 25 mm to about 40 mm, a thickness of from about 7 mm to about 10 mm, a surface Shore D hardness H2 that is greater than H1, and a 10-130 kg compression deformation of from about 2.6 mm to about 3.2 mm; an inner cover layer outward from the core layer, the inner cover layer including a third thermoplastic material and having a surface Shore D hardness H3 of from about 55 to about 70; and an outer cover layer on the surface of the golf ball including a fourth thermoplastic material and having a surface Shore D hardness H4 of from about 44 to about 56 and a 10-130 kg compression deformation of from about 2.3 mm to about 3.2 mm. The difference between the specific gravity of the core center and the specific gravity of the core layer is not more than about 0.5 g/cm 3 .

What is claimed is: 
     
         1 . A golf ball, comprising:
 a core center comprising a first thermoplastic material, wherein the core center has a diameter of from about 7 mm to about 20 mm and a surface Shore D hardness H1 of from about 30 to about 48;   a core layer comprising a second thermoplastic material disposed radially outward from the core center, wherein the core layer has a diameter of from about 25 mm to about 40 mm, a thickness of from about 7 mm to about 10 mm, a surface Shore D hardness H2 that is greater than H1, and a 10-130 kg compression deformation of from about 2.6 mm to about 3.2 mm;   an inner cover layer disposed radially outward from the core layer, wherein the inner cover layer comprises a third thermoplastic material and has a surface Shore D hardness H3 of from about 55 to about 70; and   an outer cover layer on the surface of the golf ball comprising a fourth thermoplastic material and having a surface Shore D hardness H4 of from about 44 to about 56 and a 10-130 kg compression deformation of from about 2.3 mm to about 3.2 mm,   
       wherein the difference between the specific gravity of the core center and the specific gravity of the core layer is not more than about 0.5 g/cm 3 . 
     
     
         2 . A golf ball according to  claim 1 , wherein one of the first thermoplastic material and the second thermoplastic material comprises an ionomer resin. 
     
     
         3 . A golf ball according to  claim 2 , wherein the second thermoplastic material comprises the ionomer resin and wherein the second thermoplastic material has a flexural modulus that is up to about 32,000 psi and that is greater than the flexural modulus of the first thermoplastic material. 
     
     
         4 . A golf ball according to  claim 2 , wherein the ionomer resin comprises a monomeric organic acid or salt thereof and wherein the ionomer resin is neutralized from at least about 40 to about 100%. 
     
     
         5 . A golf ball according to  claim 2 , wherein the thermoplastic material comprising the ionomer resin further comprises a polyolefin elastomer. 
     
     
         6 . A golf ball according to  claim 1 , wherein each of the first thermoplastic material and the second thermoplastic material comprises an ionomer resin which may be the same as or different from one another. 
     
     
         7 . A golf ball according to  claim 6 , wherein each ionomer resin comprises a monomeric organic acid or salt thereof and wherein each ionomer resin is neutralized from at least about 40 to about 100%. 
     
     
         8 . A golf ball according to  claim 6 , wherein at least one of the first thermoplastic material and the second thermoplastic material further comprises a polyolefin elastomer. 
     
     
         9 . A golf ball according to  claim 6 , wherein the second thermoplastic material has a flexural modulus that is up to about 32,000 psi and that is greater than the flexural modulus of the first thermoplastic material. 
     
     
         10 . A golf ball according to  claim 1 , wherein the fourth thermoplastic material comprises a polyurethane. 
     
     
         11 . A golf ball according to  claim 10 , wherein the polymeric portion of the fourth thermoplastic material consists essentially of the polyurethane. 
     
     
         12 . A golf ball according to  claim 1 , wherein the third thermoplastic material comprises a high acid ionomer resin. 
     
     
         13 . A golf ball according to  claim 1 , wherein the third thermoplastic material comprises a polyurethane. 
     
     
         14 . A golf ball according to  claim 12 , wherein the third thermoplastic material further comprises a member selected from the group consisting of low acid number ionomers and polyolefin elastomers. 
     
     
         15 . A golf ball according to  claim 1 , wherein H1 is from about 36 to about 46 Shore D, H2 is from about 40 to about 56 Shore D, H3 is from about 63 to about 68 Shore D, and H4 is from about 45 to about 52 Shore D. 
     
     
         16 . A golf ball according to  claim 15 , wherein H4 is from about 46 to about 50 Shore D. 
     
     
         17 . A golf ball according to  claim 1 , wherein the first thermoplastic material has a 10-130 kg compression deformation of at least about 3.4 mm. 
     
     
         18 . A golf ball according to  claim 1 , wherein the first thermoplastic material has a 10-130 kg compression deformation of up to about 6 mm. 
     
     
         19 . A golf ball according to  claim 18 , wherein the first thermoplastic material has a polymeric portion consisting essentially of an ionomer resin and a polyolefin elastomer. 
     
     
         20 . A golf ball according to  claim 1 , wherein the specific gravity of each of the core center and the core layer is at least about 1.01 g/cm 3 . 
     
     
         21 . A golf ball according to  claim 20 , wherein the specific gravity of each of the core center and the core layer is from about 1.02 g/cm 3  to about 1.20 g/cm 3 . 
     
     
         22 . A golf ball according to  claim 1 , wherein the core center has a diameter of about 12 mm to about 19 mm and the core layer has a diameter of from about 34 mm to about 40 mm. 
     
     
         23 . A golf ball according to  claim 1 , wherein each of the inner cover layer and the outer cover layer independently has a thickness of form about 0.6 mm to about 2.0 mm. 
     
     
         24 . A golf ball according to  claim 1 , wherein the difference between the specific gravity of the core center and the specific gravity of the core layer is not more than about 0.1 g/cm 3 .