Three-cover-layer golf ball having transparent or plasticized polyamide intermediate layer
A golf ball includes a core and a three-layer cover disposed adjacent the core. The three-layer cover includes an inner cover, an intermediate cover, and an outer cover. The inner cover includes a non-ionomeric E/Y copolymer where E is an olefin and Y is a carboxylic acid. The inner cover has a hardness of about 45 to 68 Shore D. The outer cover includes a castable thermoset polyurethane and has a hardness of about 40 to 62 Shore D. The intermediate cover layer, disposed between the inner and outer cover layers, is formed from a polyamide composition, where the polyamide composition includes a transparent polyamide having a light transmission of about 50% or greater.
1. A golf ball comprising:
a core; and
a two-layer cover disposed about the core, the two-layer cover comprising:
an inner cover layer disposed about the core, the inner layer comprising a polyamide composition; and
a castable thermoset polyurethane outer cover layer having a hardness from about 40 Shore D to about 62 Shore D;
wherein the polyamide composition comprises a transparent polyamide having a light transmission of about 50% or greater, a glass transition temperature of about 75° C. to about 160° C., and a ratio of Charpy notched impact-resistance measured at 23° C. and 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 transparent polyamide has a Charpy notched impact-resistance of about 15 kJ/m 2 or greater when measured at 23° C.
7. The golf ball of claim 6 , wherein the Charpy notched impact-resistance is about 50 kJ/m 2 or greater when measured at 23° C.
8. The golf ball of claim 1 , wherein the transparent polyamide has a light transmission of about 80% or greater.
9. The golf ball of claim 8 , wherein the light transmission is about 90% or greater.
10. The golf ball of claim 1 , wherein the transparent polyamide further comprises about 1% by weight to about 60% by weight of an acid anhydride-modified polyolefin.