Method of making filler-impregnated golf ball core

1. A method of making a golf ball core comprising the steps of:

providing a first polybutadiene pre-impregnated with at least about 50 weight percent of tungsten;

providing a second polybutadiene substantially free of tungsten;

mixing the second polybutadiene with the first polybutadiene to form a polybutadiene blend;

mixing a crosslinking agent, and a free radical initiator into the polybutadiene blend to form a reaction mixture;

placing the reaction mixture into a mold cavity;

heating and pressurizing the reaction mixture to form the golf ball core.

2. The method of claim 1 , wherein the step of mixing further includes a cis-to-trans catalyst.

3. A method of making a golf ball comprising the steps of:

providing a first polybutadiene pre-impregnated with at least about 50 weight percent of a first filler;

mixing a second polybutadiene, substantially free of the first filler, into the first polybutadiene to form a polybutadiene blend;

mixing a cis-to-trans catalyst, a crosslinking agent, and a free radical initiator into the polybutadiene blend to form a reaction product;

molding the reaction product into a golf ball core; and

forming a cover layer about the core to produce the golf ball.

4. The method of claim 3 , wherein the first polybutadiene consists of greater than about 80 percent filler, by weight.

5. The method of claim 3 , wherein the second polybutadiene consists of less than about 5 percent filler by weight.

6. The method of claim 5 , wherein the second polybutadiene consists of between about 1 percent filler by weight and about 0.05 percent filler by weight.

7. The method of claim 3 , wherein at least one of the first or second polybutadiene has a Mooney viscosity of about 40 to about 80.

8. The method of claim 3 , wherein the first or second polybutadiene has a first dynamic stiffness measured at −50° C. that is less than about 130 percent of a second dynamic stiffness measured at 0° C.

9. The method of claim 3 , wherein the cover layer is formed by injection molding, compression molding, or casting a reactive liquid.

10. The method of claim 3 , wherein the cover layer has a thickness of between about 0.05 inches and about 0.1 inches.

11. The method of claim 3 , wherein the cover layer has a loss tangent of from about 0.03 to 0.08 between a temperature of −30° C. to 20° C.

12. The method of claim 3 , wherein the cover layer has an elasticity and complex modulus of from about 5,000 to 12,000 kgf/cm 2 over a temperature of about −30° C. to 20° C.

13. The method of claim 3 , wherein the cover layer comprises natural or synthetic balata material, thermoset and thermoplastic materials, ionomers, polyamides, polyureas, polyurethanes, and styrene-butadiene rubbers.

14. The method of claim 3 , wherein the cover layer has a loss tangent of 0.16 to 0.075 over a range of −30° C. to 20° C.

15. The method of claim 14 , wherein the cover layer has a complex modulus of from about 1000 to 2800 kgf/cm 2 from −30° C. to 20° C.

16. The method of claim 3 , wherein the cover is an outer cover layer comprising polyurethane or polyurea.