Golf club having damping treatments for improved impact acoustics and ball speed

1. A golf club head comprising:

a striking face; and

a viscoelastic polymer in contact with a rear surface of the striking face,

wherein the viscoelastic polymer has a tangent of delta peak temperature between −70 degrees Celsius and −20 degrees Celsius at 1 Hz, and a tangent of delta peak temperature between 20 degrees Celsius and 50 degrees Celsius at 6 kHz.

2. The golf club head of claim 1 , wherein an elastic modulus (E), in megapascals (MPa), of the viscoelastic polymer has a relationship to a striking face thickness (t), in millimeters (mm), defined by Ê≤−14{circumflex over (t)}+305, wherein Ê is a unitless value equal to E/1 MPa and {circumflex over (t)} is a unitless value equal to t/1 mm, and wherein the thickness (t) is one of an average thickness of the striking face and a maximum thickness of the striking face.

3. The golf club head of claim 2 , wherein the relationship between E and r is further defined by Ê≥−33.24{circumflex over (t)}+63.24.

4. The golf club head of claim 2 , wherein the thickness (t) is the average thickness of the striking face.

5. The golf club head of claim 1 , wherein an elastic modulus (E), in megapascals (MPa), of the viscoelastic polymer has a relationship to an effective stiffness (S) of the striking face, in gigapascals per meter (GPa/m), defined by Ê≤−1.16Ŝ+258.33, wherein Ê is a unitless value equal to E/1 MPa and Ŝ is a unitless value equal to S/11 GPa/m, and wherein the effective stiffness S is defined as

S

=

E

face

⁢

t

A

,

wherein E face is the elastic modulus of the material of the striking face, t is a thickness of the striking face, and A is an area of the striking face.

6. The golf club head of claim 5 , wherein the relationship between E and S is further defined by Ê≥−0.33Ŝ+63.33.

7. The golf club head of claim 5 , wherein the viscoelastic polymer is a coating on the rear surface of the striking face.

8. The golf club head of claim 1 , wherein the golf club head displays a coefficient of restitution (COR) above 0.80.

9. The golf club head of claim 1 , wherein the viscoelastic polymer has a thickness between 1 mm and 15 mm.

10. The golf club head of claim 1 , wherein the viscoelastic polymer covers more than 50% of the rear surface of the striking face.

11. The golf club head of claim 1 , wherein the viscoelastic polymer substantially fills a cavity of the golf club head.

12. The golf club head of claim 1 , wherein the polymer comprises at least one of butyl rubbers, butyl rubber ionomers, polyurethanes, polyureas, silicones, acrylate, methacrylates, foamed polymers, epoxies, styrene block copolymers, polybutadiene, nitrile rubber, thermoplastic vulcanizates, and thermoplastic elastomers.

13. A golf club head comprising:

a striking face having a thickness (t); and

a viscoelastic polymer, having an elastic modulus (E), in contact with a rear surface of the striking face, wherein the viscoelastic polymer has a tangent of delta peak temperature between 20 degrees Celsius and 50 degrees Celsius at 6 kHz;

wherein the elastic modulus (E), in megapascals (MPa), of the viscoelastic polymer has a relationship to the striking face thickness (t), in millimeters (mm), defined by Ê≤−14{circumflex over (t)}+305, wherein Ê is a unitless value equal to E/1 MPa and {circumflex over (t)} is a unitless value equal to t/1 mm, and wherein the thickness (t) is one of an average thickness of the striking face and a maximum thickness of the striking face.

14. The golf club head of claim 13 , wherein the relationship between E and t is further defined by Ê≥−33.24{circumflex over (t)}+63.24.

15. The golf club head of claim 14 , wherein the elastic modulus (E), in megapascals (MPa), of the viscoelastic polymer has a relationship to an effective stiffness (S) of the striking face, in gigapascals per meter (GPa/m), defined by Ê<−1.16Ŝ+258.33, wherein Ê is a unitless value equal to E/1 MPa and Ŝ is a unitless value equal to S/1 GPa/m, and wherein the effective stiffness S is defined as

S

=

E

face

⁢

t

A

,

wherein E face is the elastic modulus of the material of the striking face and A is an area of the striking face.

16. The golf club head of claim 15 , wherein the relationship between E and S is further defined by Ê≥−0.33Ŝ+63.33.

17. The golf club head of claim 14 , wherein the viscoelastic polymer has a tangent of delta peak temperature between −10 degrees Celsius and 40 degrees Celsius at 1 kHz.

18. A golf club head comprising:

a striking face having an effective stiffness (S); and

a viscoelastic polymer, having an elastic modulus (E), in contact with a rear surface of the striking face, wherein the viscoelastic polymer has a tangent of delta peak temperature between 20 degrees Celsius and 50 degrees Celsius at 6 kHz;

wherein the elastic modulus (E), in megapascals (MPa), of the viscoelastic polymer has a relationship to the effective stiffness (S) of the striking face, in gigapascals per meter (GPa/m), defined by Ê<−1.16Ŝ+258.33, wherein Ê is a unitless value equal to E/1 MPa and Ŝ is a unitless value equal to S/1 GPa/m, and wherein the effective stiffness S is defined as

S

=

E

face

⁢

t

A

,

wherein E face is the elastic modulus of the material of the striking face, t is a thickness of the striking face, and A is an area of the striking face.

19. The golf club head of claim 18 , wherein the relationship between E and S is further defined by Ê≥−0.33Ŝ+63.33.