Three-cover-layer golf ball having transparent or plasticized polyamide intermediate layer

1. A golf ball comprising:

a core; and

a cover disposed adjacent the core, the cover comprising:

a non-ionomeric inner cover layer comprising an E/Y copolymer where E is an olefin and Y is a carboxylic acid, the inner cover being disposed about the core and having a hardness of 45 Shore D to 68 Shore D;

a castable thermoset polyurethane outer cover layer having a hardness between 40 Shore D and 62 Shore D; and

an intermediate cover layer disposed between the inner and outer cover layers, the intermediate layer comprising a polyamide composition;

wherein the polyamide composition comprises a transparent polyamide having a light transmission of about 50% or greater and has a ratio of Charpy notched impact-resistance measured at 23° C. and measured at −30° C. of at least about 2.0.

2. The golf ball of claim 1 , wherein the transparent polyamide comprises a transparent polyether-amide block copolymer.

3. The golf ball of claim 1 , wherein the transparent polyamide has an amorphous, quasi-amorphous, semicrystalline, or microcrystalline structure.

4. The golf ball of claim 1 , wherein the transparent polyamide has a glass transition temperature in the range of about 75° C. to about 160° C.

5. The golf ball of claim 4 , wherein the transparent polyamide has a glass transition temperature in the range of about 80° C. to about 95° C.

6. The golf ball of claim 1 , wherein the Charpy notched impact-resistance is about 50 kJ/m 2 or greater when measured at 23° C.

7. The golf ball of claim 1 , wherein the transparent polyamide has a light transmission of about 80% or greater.

8. The golf ball of claim 7 , wherein the light transmission is about 90% or greater.

9. The golf ball of claim 1 , wherein the intermediate layer hardness is greater than the inner cover layer hardness.

10. The golf ball of claim 9 , wherein the intermediate layer hardness is greater than the inner cover layer hardness by at least 5 Shore D.

11. The golf ball of claim 1 , wherein the intermediate layer hardness is greater than the outer cover layer hardness.

12. The golf ball of claim 11 , wherein the intermediate layer hardness is greater than the outer cover layer hardness by at least 5 Shore D.

13. The golf ball of claim 1 , wherein the core comprises a center and at least one outer core layer.

14. The golf ball of claim 1 , wherein the non-ionomeric inner cover layer further comprises a polyester/polycarbonate blend, a polyester resin, an acetal resin, a polyamide resin, a polyetheramide resin, a polyester resin, a polyester elastomer, a liquid crystalline polyester, a polyester/polyamide blend, a poly(arylene ether)/polyester resin, or a polyimide.

15. The golf ball of claim 1 , wherein the olefin is ethylene and the carboxylic acid is acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, or a combination thereof.

16. A golf ball comprising:

a core; and

a cover disposed adjacent the core, the cover comprising:

a non-ionomeric inner cover layer comprising an E/Y copolymer where E is an olefin and Y is a carboxylic acid, the inner cover being disposed about the core and having a hardness of 45 Shore D to 68 Shore D;

a castable thermoset polyurethane outer cover layer having a hardness between 40 Shore D and 62 Shore D; and

an intermediate cover layer disposed between the inner and outer cover layers, the intermediate layer comprising a polyamide composition;

wherein the polyamide composition comprises a transparent polyamide having a light transmission of about 50% or greater, and about 1% by weight to about 60% by weight of an acid anhydride-modified polyolefin.