Golf ball 2 has core 4 , cover 6 and paint layer 12 . The base polymer of the cover 6 includes a thermoplastic polyurethane elastomer. The cover includes 0.1 parts by weight or more and 10 parts by weight or less of a hindered amine heat and light resistance stabilizer having a hindered phenol group, per 100 parts by weight of the base polymer. Preferably, the hindered amine heat and light resistance stabilizer has two or more hindered phenol groups in the molecule. It is preferred that the cover 6 further includes an ultraviolet ray absorbing agent and a heat resistance stabilizer. Provided that the molar concentration of the hindered amine heat and light resistance stabilizer is defined as A, and the molar concentration of the ultraviolet ray absorbing agent is defined as B, the molar ratio (A/B) is preferably 0.01 or greater and 2.5 or less. The cover 6 may further include a heat resistance stabilizer.
1. A golf ball which comprises a core and a cover,
the base polymer of the cover comprising a thermoplastic polyurethane elastomer, and
the cover comprising 0.1 parts by weight or more and 10 parts by weight or less of a hindered amine heat and light resistance stabilizer having two or more hindered phenol groups, per 100 parts by weight of the base polymer, an ultraviolet ray absorbing agent, a heat resistance stabilizer, and titanium oxide; and
provided that if the molar concentration of the hindered amine heat and light resistance stabilizer is defined as A; the molar concentration of the ultraviolet ray absorbing agent is defined as B; and the molar concentration of the heat resistance stabilizer is defined as C,
the molar ratio (A/B) is 0.01 or greater and 2.5 or less,
while the molar ratio [(A+C)/B] is 0.01 or greater and 2.5 or less, and
wherein the cover has shore D hardness of 40 or greater and 55 or less.
2. The golf ball according to claim 1 , wherein the principal component of the thermoplastic polyurethane elastomer is a reaction product of diphenylmethane diisocyanate (MDI) and polyether polyol.
3. The golf ball according to claim 1 , wherein the cover comprises 0.01 parts by weight or more and 10 parts by weight or less of the ultraviolet ray absorbing agent per 100 parts by weight of the base polymer.
4. The golf ball according to claim 1 , wherein the ultraviolet ray absorbing agent is a benzotriazole based agent.
5. The golf ball according to claim 1 , wherein the heat resistance stabilizer is a hindered phenol based agent.
6. The golf ball according to claim 1 , wherein the hindered amine heat and light resistance stabilizer is 1-[2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine.
7. The golf ball according to claim 1 , wherein the ball is a range ball.
8. The golf ball according to claim 3 , wherein the ultraviolet ray absorbing agent is a benzotriazole based agent.
9. The golf ball according to claim 8 , wherein the heat resistance stabilizer is a hindered phenol based agent.
10. The golf ball according to claim 1 , wherein the cover has shore D hardness of 42 or greater and 50 or less.
11. The golf ball according to claim 1 , wherein the molar ratio (A/B) is 0.1 or greater and 2.3 or less, and the molar ratio [(A+C)/B] is 0.1 or greater and 2.3 or less.
12. The golf ball according to claim 9 , wherein the molar ratio (A/B) is 0.1 or greater and 2.3 or less, and the molar ratio [(A+C)/B] is 0.1 or greater and 2.3 or less.
13. The golf ball according to claim 12 , wherein the cover has shore D hardness of 42 or greater and 50 or less.