Golf ball compositions
View Patent ↗The present invention is directed to thermoset rubber compositions comprising from 1 phr to 20 phr of a zinc ionomer. The thermoset rubber composition is used to form at least one layer of a one-piece, two-piece, or multi-layer golf ball.
1. A golf ball comprising a layer formed from a thermoset rubber composition, wherein the thermoset rubber composition consists essentially of the reaction product of:
a base rubber;
a peroxide initiator agent;
a coagent selected from the group consisting of metal salts of acrylates, diacrylates, methacrylates, and dimethacrylates, wherein the metal is selected from magnesium, calcium, zinc, aluminum, lithium, nickel, and sodium;
from 1 phr to 15 phr of an E/X/Y-type ionomer composition of ethylene (E), an α,β-unsaturated carboxylic acid (X), and optionally a softening comonomer (Y), wherein at least 70% of all acid groups present in the ionomer composition are neutralized with a zinc cation;
from 0 phr to 1 phr of zinc oxide; and
optionally a soft and fast agent selected from halogenated organosulfur compounds and metal salts thereof.
2. The golf ball of claim 1 , wherein the amount of elemental zinc present in the thermoset rubber composition is less than 1 wt %, based on the total weight of the thermoset rubber composition.
3. The golf ball of claim 1 , wherein the amount of elemental zinc present in the thermoset rubber composition is less than 0.7 wt %, based on the total weight of the thermoset rubber composition.
4. The golf ball of claim 1 , wherein the coagent is selected from the group consisting of zinc salts of unsaturated carboxylic acids.
5. The golf ball of claim 4 , wherein the amount of elemental zinc present in the thermoset rubber composition, excluding zinc present in the coagent, is less than 1 wt %, based on the total weight of the thermoset rubber composition.
6. The golf ball of claim 4 , wherein the amount of elemental zinc present in the thermoset rubber composition, excluding zinc present in the coagent, is less than 0.7 wt %, based on the total weight of the thermoset rubber composition.
7. The golf ball of claim 1 , wherein the ionomer composition has a melt index (190° C., 2.16 kg) of greater than 0.5 g/10 min.
8. The golf ball of claim 1 , wherein the ionomer composition has a melt index (190° C., 2.16 kg) of 0.7 or greater.
9. The golf ball of claim 1 , wherein the layer formed from the thermoset rubber composition has a specific gravity of less than 1.07 g/cm 3 .
10. The golf ball of claim 1 , wherein the layer formed from the thermoset rubber composition has a specific gravity of less than 1.05 g/cm 3 .
11. The golf ball of claim 1 , wherein the layer formed from the thermoset rubber composition has a specific gravity of less than 1.03 g/cm 3 .