Golf Balls having a Casing Layer Formed from a Single High Acid Based Ionomer with an Ultra High Melt Flow Index Maleic Anhydride Terpolymer

Abstract

The present invention is a multi-piece golf ball having a casing layer comprising of a single high acid based ionomer that is blended with an ultra high melt flow index maleic anhydride terpolymer with a melt flow index of at least 70 g/10 min. at 190° C. The maleic anhydride terpolymer comprises a copolymer of ethylene-alkyl acrylate-maleic anhdydride. The alkyl acrylate is selected from methyl, or ethyl, or propyl, or butyl, or pentyl acrylate. The maleic anhydride content in the terpolymer is 1 to 4% of the total blend by weight. The single high acid ionomer such as a copolymer of ethylene-acrylic or methacrylic is partially neutralized with a suitable cation such as lithium, sodium, magnesium, zinc, or potassium.

1 . A multi-layer golf ball comprising at least a casing layer, a cover, and a core, wherein the casing layer is formed from an ultra high melt flow index maleic anhydride terpolymer blended with a single high acid based ionomer wherein the terpolymer has a melt flow index of at least 70 g/10 min. at 190° C. 
   
   
       2 . A golf ball according to  claim 1 , wherein the ultra high melt flow index of the terpolymer is about 20 to 250 g/10 min. at 190° C. 
   
   
       3 . A golf ball according to  claim 1 , wherein the ultra high melt flow index of the terpolymer is about 70 to 225 g/10 min. at 190° C. 
   
   
       4 . A golf ball according to  claim 1 , wherein the ultra high melt flow index of the terpolymer is about 175 to 225 g/10 min. at 190° C. 
   
   
       5 . The golf ball according to  claim 1 , wherein the maleic anhydride terpolymer comprises a copolymer of ethylene-alkyl acrylate-maleic anhydride. 
   
   
       6 . The golf ball according to  claim 5 , wherein the alkyl acrylate is selected from the group consisting of methyl, or ethyl, or propyl, or butyl, or pentyl acrylate. 
   
   
       7 . The golf ball according to  claim 6 , wherein the alkyl acrylate in the terpolymer is ethyl acrylate. 
   
   
       8 . The golf ball according to  claim 1 , wherein the maleic anhydride terpolymer comprises about 1 to 4 wt % of maleic anhydride. 
   
   
       9 . The golf ball according to  claim 1 , wherein the maleic anhydride terpolymer has a flexural modulus in the range of 1,000 to 20,000 psi. 
   
   
       10 . The golf ball according to  claim 1 , wherein the single high acid ionomer is ethylene-acrylic or methacrylic acid and they are neutralized with a cation selected from the group consisting of lithium, sodium, magnesium, zinc, or potassium. 
   
   
       11 . The golf ball according to  claim 10 , wherein the neutralization level for the ionomer is about 30 to 70% by weight. 
   
   
       12 . The golf ball according to  claim 10 , wherein the acid content is about 16 to 25% by weight. 
   
   
       13 . The golf ball according to  claim 1 , wherein the maleic anhydride terpolymer has a melting point in the range of 65 to 108° C. 
   
   
       14 . The golf ball according to  claim 13 , wherein the maleic anhydride terpolymer has a melting point in the range of 100 to 102° C. 
   
   
       15 . The golf ball according to  claim 1 , wherein the melt flow index of the ionomer in the casing layer is about 1 to 5 g/10 min. at 190° C. 
   
   
       16 . The golf ball according to  claim 15 , wherein the melt flow index of the ionomer in the casing layer is about 2.5 to 4.5 g/10 min. at 190° C. 
   
   
       17 . The golf ball according to  claim 1 , wherein the cover is formed from a thermoset polyurethane or polyurea. 
   
   
       18 . The golf ball according to  claim 17 , wherein the cover has a thickness of 0.025 to 0.045 inch. 
   
   
       19 . The golf ball according to  claim 1 , wherein the casing layer has a thickness of 0.030 to 0.050 inch. 
   
   
       20 . The golf ball according to  claim 1 , wherein the maleic anhydride terpolymer composition in the casing layer is about 10 to 40% by weight. 
   
   
       21 . The golf ball according to  claim 20 , wherein the maleic anhydride terpolymer composition in the casing layer is about 15 to 30% by weight. 
   
   
       22 . The golf ball according to  claim 21 , wherein the maleic anhydride terpolymer composition in the casing layer is about 16 to 25% by weight. 
   
   
       23 . The golf ball according to  claim 1 , wherein the core further includes a core layer around the core. 
   
   
       24 . The golf ball according to  claim 23 , wherein the core has a diameter from about 0.5 to 1.25 inches and the core layer has a thickness from about 0.25 to 0.50 inch.