Golf balls comprising highly-neutralized acid polymers

Abstract

A golf ball includes a dual core having an Atti compression of 70 or less and a diameter of 0.5 to 1.55 inches. An inner core and outer core are formed from a thermoset rubber composition and have a first and second hardness, respectively. An inner cover layer including an ionomer and having a hardness of 40 to 70 Shore D and being greater than the first hardness by at least 10 Shore D and an intermediate layer formed from a polymer neutralized by an organic acid or a salt thereof, and sufficient cation source present in an amount sufficient to neutralize the polymer by 80% or greater, are disposed between the core and an outer cover, which is formed from a polyurethane and having a thickness of 0.04 inches or less and a hardness of 55 Shore D or less.

1 . A golf ball comprising:
 a core comprising an inner core layer and an outer core layer, the inner core layer comprising a thermoset polybutadiene rubber composition having a first hardness; and the outer core layer having a second hardness and comprising a polymer comprised of an acid group fully-neutralized by an organic acid or a salt of the organic acid or a suitable base of the organic acid, and sufficient cation source to complete the neutralization;   an intermediate layer having a third hardness of about 40 Shore D to about 70 Shore D;   an inner cover layer; and   an outer cover layer;   wherein the inner cover layer and the outer cover layer comprise ionomeric copolymers and terpolymers, ionomer precursors, thermoplastics, thermoplastic elastomers, polybutadiene rubber, balata, grafted metallocene-catalyzed polymers, non-grafted metallocene-catalyzed polymers, single-site polymers, high-crystalline acid polymers and their ionomers, polyurethanes, polyureas, polyurethane-ureas; polyurea-urethanes; cationic ionomers; or castable reactive liquid materials;   wherein the first hardness is about 50 Shore A to about 55 Shore D and first hardness is less than the second Shore D hardness.   
   
   
       2 . The golf ball of  claim 1 , wherein the cation source is selected from a group consisting of metal cations of lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, or aluminum. 
   
   
       3 . The golf ball of  claim 1 , wherein the organic acid is selected from the group consisting of aliphatic organic acids, aromatic organic acids, saturated mono-functional organic acids, unsaturated mono-functional organic acids, and multi-unsaturated mono-functional organic acids. 
   
   
       4 . The golf ball of  claim 1 , wherein the salt of organic acids comprise the salts of barium, lithium, sodium, zinc, bismuth, chromium, cobalt, copper, potassium, strontium, titanium, tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin, calcium, stearic, behenic, erucic, oleic, linoelic, dimerized derivatives, and mixtures thereof. 
   
   
       5 . The golf ball of  claim 1 , wherein the inner cover layer has a hardness of about 60 Shore D or greater and the outer cover layer has a hardness of 60 Shore D or less. 
   
   
       6 . The golf ball of  claim 1 , wherein the cover layer a castable reactive liquid material and has a thickness of about 0.04 inches or less. 
   
   
       7 . The golf ball of  claim 1 , wherein the intermediate layer has a hardness of about 62 Shore D or greater. 
   
   
       8 . The golf ball of  claim 1 , wherein the core has a diameter of about 1.4 inches or greater. 
   
   
       9 . The golf ball of  claim 1 , wherein the intermediate layer comprises an ionomer. 
   
   
       10 . The golf ball of  claim 1 , wherein the outer cover layer comprises polyurethane. 
   
   
       11 . The golf ball of  claim 1 , wherein the core compression is no greater than about 80. 
   
   
       12 . The golf ball of  claim 1 , wherein the third hardness is at least 10 Shore D greater than the first hardness. 
   
   
       13 . The golf ball of  claim 1 , wherein the outer cover layer has a fourth hardness and a ratio of the third hardness to the fourth hardness is about 1.5 or greater. 
   
   
       14 . The golf ball of  claim 1 , wherein the first hardness is less than the second Shore D hardness by at least about 10 points. 
   
   
       15 . A golf ball comprising:
 a core comprising an inner core layer and an outer core layer and having an Atti compression of about 70 or less and a diameter of about 0.5 inches to about 1.55 inches, the inner core layer comprising a thermoset polybutadiene rubber composition having a first hardness; and the outer core layer comprising a thermoset polybutadiene rubber composition and having a second hardness;   an inner cover layer comprising an ionomer, and having a hardness of about 40 Shore D to about 70 Shore D and being greater than the first hardness by at least 10 Shore D;   an intermediate layer formed from a polymer neutralized by an organic acid or a salt of the organic acid, and sufficient cation source present in an amount sufficient to neutralize the polymer by 80% or greater; and   an outer cover layer;   wherein the outer cover layer comprises a polyurethane, has a thickness of about 0.04 inches or less, and has a hardness of about 55 Shore D or less.   
   
   
       16 . The golf ball of  claim 15 , wherein the core diameter is about 1.4 inches to about 1.55 inches. 
   
   
       17 . The golf ball of  claim 15 , wherein the inner cover layer has a hardness of about 62 Shore D or greater. 
   
   
       18 . The golf ball of  claim 15 , wherein the organic acid or salt of the organic acid is present in an amount of about 10 wt % or greater. 
   
   
       19 . The golf ball of  claim 15 , wherein the polymer is neutralized by 90% or greater. 
   
   
       20 . The golf ball of  claim 19 , wherein the polymer is neutralized by 100%.