Urethane elastomers with improved color stability
View Patent ↗A golf ball including a center, a cover, and, optionally, at least one intermediate layer disposed between the center and the cover, wherein the cover is formed from a polyurethane composition, or a reaction product thereof, including at least one polyol; at least one polyisocyanate; at least one curing agent; and at least one color stabilizer; wherein the color stabilizer is present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.
1. A golf ball comprising a center and a cover, wherein the cover has a color lightness, L*, of greater than about 86 following exposure to UV light at an irradiance power of 1.00 W/m 2 /nm for a period of about 1 hour to about 4 hours, and the cover comprises:
a reaction product comprises a polyurea formed from a prepolymer and a
curing agent; and
at least one color stabilizer comprising a benzoate having the formula:
wherein R 1 is hydroxyalkylether, alkyl, or hydroxyphenyl; R 2 is H, OH, alkyl, hydroxy(alkylether)amino; R 3 is H, alkyl, or OH; and R 4 is H alkyl; and
wherein the cover comprises an inner cover layer and an outer cover layer disposed about the inner cover layer, the outer cover layer comprising the reaction product.
2. The golf ball of claim 1 , wherein the cover lightness L* after the UV exposure is greater than about 87.
3. The golf ball of claim 1 , wherein the cover after the UV exposure exhibits a change in the color lightness, ΔL*, of no less than about −7 as compared to the cover before the UV exposure.
4. The golf ball of claim 3 , wherein the ΔL* is no less than about −5.8.
5. The golf ball of claim 3 , wherein the ΔL* is no less than about −4.
6. The golf ball of claim 1 , wherein the cover has a color saturation, C*, of less than about 25 following the UV exposure.
7. The golf ball of claim 6 , wherein the color saturation C* after the UV exposure is less than about 23.
8. The golf ball of claim 7 , wherein the color saturation C* after the UV exposure is less than about 20.
9. The golf ball of claim 6 , wherein the cover before the UV exposure has an initial C* of less than about 5.
10. The golf ball of claim 9 , wherein the initial C* is less than about 4.
11. The golf ball of claim 9 , wherein the cover exhibits a difference between the color saturation after the UV exposure and the initial C* before the UV exposure, identified as ΔC*, of less than about 22.
12. The golf ball of claim 11 , wherein the ΔC* is less than about 18.
13. The golf ball of claim 11 , wherein the ΔC* is less than about 15.
14. The golf ball of claim 6 , wherein the cover after the UV exposure has a ratio of C* to L* of less than about 0.29.
15. The golf ball of claim 14 , wherein the ratio of C* to L* of the cover after the UV exposure is less than about 0.25.
16. The golf ball of claim 15 , wherein the ratio of C* to L* of the cover after the UV exposure is less than about 0.18.
17. The golf ball of claim 6 , wherein the cover before the UV exposure has a ratio of C* to L* of less than about 0.04.
18. The golf ball of claim 1 , wherein the at least one color stabilizer is present in an amount of about 1% to about 7% by weight of the reaction product.
19. The golf ball of claim 1 , wherein the cover further comprises a second color stabilizer present in an amount less than that of the at least one color stabilizer.
20. The golf ball of claim 19 , wherein the second color stabilizer is present in an amount of about 0.1% to about 1% by weight of the reaction product.
21. The golf ball of claim 1 , wherein the reaction product further comprises an antioxidant.
22. The golf ball of claim 1 , further comprising an intermediate layer disposed between the center and the cover.
23. A golf ball comprising a center and a cover, wherein the cover exhibits a color lightness, L*, of greater than about 86 and a change in the color lightness, ΔL*, of no less than about −4 following exposure to UV light at an irradiance power of 1.00 W/m 2 /nm for a period of 1 hour, and the cover comprises:
a reaction product comprising a prepolymer and a curing agent;
a UV stabilizer comprising a benzoate having the formula:
wherein R 1 is hydroxyalkylether, alkyl, hydroxyphenyl; R 2 is H, OH, alkyl, hydroxy(alkylether)amino; R 3 is H, alkyl, OH; and R 4 is H, alkyl, and being present in a first amount of about 3% to about 7% by weight of the reaction product; and
a light stabilizer present in a second amount of about 0.05% to about 1% by weight of the reaction product.
24. The golf ball of claim 23 , wherein the reaction product is a polyurea and further comprises an antioxidant.
25. A golf ball comprising a center, a cover, and at least one intermediate layer disposed between the center and the cover, wherein the cover has a ratio of an initial color saturation to an initial color lightness of less than about 0.04, and the cover comprises:
a reaction product of a prepolymer and a curing agent;
a UV absorber comprising a benzoate having the formula:
wherein R 1 is hydroxyalkylether, alkyl, or hydroxyphenyl; R 2 is hydroxy(alkylether)amino; R 3 is H, alkyl, or OH; and R 4 is H or alkyl, and being present in a first amount; and
a light stabilizer present in a second amount less than the first amount.