An object of the present invention is to provide a golf ball which is excellent in abrasion-resistance and durability. The golf ball of the present invention comprises a cover using a cover composition containing thermoplastic polyurethane (A) and a polyisocyanate mixture (B) in which a urethane prepolymer (b-1a) having at least two isocyanate groups or a polyisocyanate (b-1b) having at least three isocyanate groups is dispersed in a thermoplastic resin (b-2) which does not substantially react with the isocyanate groups.
1. A golf ball comprising a core and a cover,
wherein the cover is made from a cover composition containing, as a resin component, a thermoplastic polyurethane (A) and a polyisocyanate mixture (B) in which a urethane prepolymer (b-1a) having at least two isocyanate groups is dispersed in a thermoplastic resin (b-2) which does not substantially react with the isocyanate groups,
the polyisocyanate mixture (B) containing the urethane prepolymer (b-1a) has a NCO content (NCO %) of 0.1 mass % to 5.0 mass %, and
the urethane prepolymer (b-1a) has a NCO content (NCO %) of 0.1 mass % to 7.0 mass %.
2. The golf ball according to claim 1 , wherein the thermoplastic resin (b-2) which does not substantially react with the isocyanate groups is at least one kind selected from the group consisting of a polyester elastomer, an acrylic elastomer, a styrene elastomer, an olefin elastomer, and a vinyl chloride elastomer.
3. The golf ball according to claim 1 , wherein the cover composition contains the polyisocyanate mixture (B) in an amount of 1 part to 50 parts by mass based on 100 parts by mass of the thermoplastic polyurethane (A).
4. The golf ball according to claim 2 , wherein the cover composition contains the polyisocyanate mixture (B) in an amount of 1 part to 50 parts by mass based on 100 parts by mass of the thermoplastic polyurethane (A); wherein the urethane prepolymer (b-1a) has a number average molecular weight of 1000 to 30000; and wherein the urethane prepolymer (b-1a) is an isocyanate group terminated urethane prepolymer selected from the group consisting of 4,4′-diphenylmethane diisocyanate based urethane prepolymer, tolylene diisocyanate based urethane prepolymer, and 4,4′-dicyclohexylmethane diisocyanate based urethane prepolymer.
5. The golf ball according to claim 4 , wherein the urethane prepolymer (b-1a) and the thermoplastic resin (b-2) are blended in the polyisocyanate mixture (B) (a total of 100 mass %) in a ratio of the urethane prepolymer (b-1a)/the thermoplastic resin (b-2) in a range of 5 mass % to 50 mass %/50 mass % to 95 mass %.
6. The golf ball according to claim 1 , wherein the urethane prepolymer (b-1a) has a number average molecular weight of 1000 to 30000.
7. The golf ball according to claim 1 , wherein the urethane prepolymer (b-1a) is an isocyanate group terminated urethane prepolymer selected from the group consisting of 4,4′-diphenylmethane diisocyanate based urethane prepolymer, tolylene diisocyanate based urethane prepolymer, and 4,4′-dicyclohexylmethane diisocyanate based urethane prepolymer.
8. The golf ball according to claim 1 , wherein the urethane prepolymer (b-1a) and the thermoplastic resin (b-2) are blended in the polyisocyanate mixture (B) (a total of 100 mass %) in a ratio of the urethane prepolymer (b-1a)/the thermoplastic resin (b-2) in a range of 5 mass % to 50 mass %/50 mass % to 95 mass %.
9. The golf ball according to claim 1 , wherein a number average molecular weight of a polyol component constituting the urethane prepolymer (b-1a) is 650 or more.
10. The golf ball according to claim 1 , wherein shore D hardness of the cover is from 20 to 60.