Multi-layer core golf ball
Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core has a very high positive hardness gradient and comprises at least three layers, including at least one thermoset layer and at least one thermoplastic layer.
1. A golf ball comprising a core and cover, the core comprising:
a solid inner core layer formed from an unfoamed first thermoset composition and having a diameter of from 0.50 inches to 1.45 inches and a center Shore C hardness (H center ) of 50 or less;
an intermediate core layer formed from a thermoplastic composition and having a thickness of from 0.01 inches to 0.20 inches; and
an outer core layer formed from a second thermoset composition and having a thickness of 0.15 inches or greater and an outer surface Shore C hardness (H outer surface ) of 70 or greater; and
wherein H outer surface −H center ≥60.
2. The golf ball of claim 1 , wherein the inner core layer has a compression of <20.
3. The golf ball of claim 2 , wherein the core has an overall compression of ≥45.
4. The golf ball of claim 1 , wherein the inner core layer has a compression of <10.
5. The golf ball of claim 1 , wherein H center ≤40.
6. A golf ball comprising a core and cover, the core comprising:
a solid inner core layer formed from an unfoamed first thermoset composition and having a diameter of from 0.50 inches to 1.45 inches and a center Shore C hardness (H center );
an intermediate core layer formed from a thermoplastic composition and having a thickness of from 0.01 inches to 0.20 inches; and
an outer core layer formed from a second thermoset composition and having a thickness of 0.15 inches or greater and an outer surface Shore C hardness (H outer surface )of 70 or greater; and
wherein H center ≤30, and wherein H outer surface −H center ≥40.
7. The golf ball of claim 6 , wherein H outer surface ≥80.
8. The golf ball of claim 6 , wherein the thermoset composition of the inner core layer consists essentially of:
polybutadiene;
from 0.1 phr to 2.0 phr of a peroxide;
optionally 5 phr or less of a metal oxide;
optionally 5 phr or less of a metal coagent;
optionally 5 phr or less of a metal carbonate; and
optionally one or more additional components selected from the group consisting of fillers, colorants, and antioxidants.
9. A golf ball comprising a core and cover, the core comprising:
a solid inner core layer formed from an unfoamed first thermoset composition and having a diameter of from 0.25 inches to 1.10 inches and a center Shore C hardness (H center ) of 50 or less;
an intermediate core layer formed from a thermoplastic composition and having a thickness of from 0.01 inches to 0.20 inches; and
an outer core layer formed from a second thermoset composition and having a thickness of 0.10 inches or greater and an outer surface Shore C hardness (H outer surface ) of 60 or greater; and
wherein H outer surface −H center ≥60.
10. The golf ball of claim 9 , wherein the inner core layer has a compression of <20.
11. The golf ball of claim 10 , wherein the core has an overall compression of ≥45.
12. The golf ball of claim 9 , wherein the thermoset composition of the inner core layer consists essentially of:
polybutadiene;
from 0.1 phr to 2.0 phr of a peroxide;
optionally 5 phr or less of a metal oxide;
optionally 5 phr or less of a metal coagent;
optionally 5 phr or less of a metal carbonate; and
optionally one or more additional components selected from the group consisting of fillers, colorants, and antioxidants.