Abstract: A golf ball 2 includes a core 4, a first mid layer 6, a second mid layer 8, and a cover 12. The core 4 includes a center 18 and an envelope layer 20. The center 18 is formed by crosslinking a first rubber composition, and the envelope layer 20 is formed by crosslinking a second rubber composition. The first rubber composition or the second rubber composition includes a base rubber, a co-crosslinking agent, a crosslinking initiator, and an acid and/or a salt. The co-crosslinking agent is: (1) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms; and/or (2) a metal salt of an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms. A hardness Hm2 of the second mid layer 8 is greater than a hardness Hm1 of the first mid layer 6. The hardness Hm2 is greater than a hardness Hc of the cover 12.

Abstract: A golf ball 2 includes a core 4, amid layer 6, a reinforcing layer 8, and a cover 10. The core 4 includes a center 12 and an envelope layer 14. The envelope layer 14 is formed by a rubber composition being crosslinked. The rubber composition includes a base rubber (a), a co-crosslinking agent (b), a crosslinking initiator (c), and an acid and/or a salt (d). The co-crosslinking agent (b) is: (b1) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms; or (b2) a metal salt of an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms.

Abstract: The present invention provides a golf ball comprising a spherical core composed of a spherical inner core layer and an outer core layer, an intermediate layer and a cover, wherein the inner core layer has a hardness difference (Hs1?Ho) between a surface hardness (Hs1) and a center hardness (Ho) of 5 or less in JIS-C hardness, the outer core is such that R2 of a linearly approximated curve obtained from a least square method is 0.95 or higher, when JIS-C hardness, measured at nine points obtained by dividing a thickness of the outer core in a radius direction of the spherical core into equal parts having 12.5% intervals therebetween, is plotted against distance (%) from a border point between the outer core layer and the inner core layer, and the intermediate layer has a slab hardness which is greater than a slab hardness of the cover.

Abstract: A golf ball includes a spherical core, a mid layer, an inner cover, and an outer cover. A hardness Hm of the mid layer is greater than a hardness Hinc of the inner cover which is greater than a hardness Houc of the outer cover. A difference (Hm?Houc) is greater than 25. A volume Vm of the mid layer is greater than a volume Vinc of the inner cover which is greater than a volume Vouc of the outer cover. A ratio [(Vm+Vinc+Vouc)/V] of a sum (Vm+Vinc+Vouc) relative to a volume V of an entirety of the golf ball is less than 0.30. A ratio (Vm/Vouc) is greater than 1.50. A product (Vm*Hm) and a product (Vouc*Houc) meet the following relationship: [(Vm*Hm)/(Vouc*Houc)]>3.0.

Abstract: A golf ball 2 includes a core 4, a mid layer 6, a reinforcing layer 8, and a cover 10. When distances (%) from the central point of the core 4 to nine points and JIS-C hardnesses at the nine points, which are obtained by dividing a region from the central point of the core 4 to the surface of the core 4 at intervals of 12.5% of the radius of the core 4, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. The difference (H(100)-H(0)) between a JIS-C hardness H(100) at the surface of the core 4 and a JIS-C hardness H(0) at the central point of the core 4 is equal to or greater than 15.

Abstract: Provided is a golf ball is excellent in flight distance performance, approach performance, and feel at impact. A ball 2 includes a core 4, a mid layer 6, and a cover 8. The core 4 includes an inner core 10 and an outer core 12. The cover 8 includes an inner layer cover 10 and an outer layer cover 12. An inner core volume Vc, a mid layer volume Vm, a mid layer hardness Hm, an inner layer cover volume Vinc, an inner layer cover hardness Hinc, an outer layer cover volume Vouc, an outer layer cover hardness Houc, and a ball volume V meet the following relational expressions (a) to (g): (a) Vc/V<0.07, (b) Hm>Hinc>Houc, (c) Hm?Houc>25, (d) Vm>Vinc>Vouc, (e) (Vm+Vinc+Vouc)/V<0.30, (f) Vm/Vouc>1.50, and (g) (Vm*Hm)/(Vouc*Houc)>3.0.

Abstract: A golf ball 2 includes a spherical core 4, an inner mid layer 6, an outer mid layer 8, a reinforcing layer 10, and a cover 12. When distances (%) from a central point of the core 4 to nine points and JIS-C hardnesses at the nine points, which nine points are obtained by dividing a region from the central point of the core 4 to a surface of the core 4 at intervals of 12.5% of a radius of the core 4, are plotted in a graph, R2 of a linear approximation curve obtained by a least-square method is equal to or greater than 0.95. Hm1 is greater than Hm2. Hc is less than Hm1. T2 is equal to or greater than 0.5 mm but equal to or less than 1.6 mm.

Abstract: A golf ball includes a core, a mid layer, and a cover. The core includes an inner core, a mid core, and an outer core. The mid layer includes an inner mid layer and an outer mid layer. A hardness H(C) is equal to or greater than a hardness H(B). A hardness H(E) is equal to or greater than a hardness H(D). An angle ? is calculated by (Formula 1). An angle ? is calculated by (Formula 2). The angle ? is 0° or greater. A difference (???) is 0° or greater. A hardness Hm2 of the outer mid layer is greater than a hardness Hm1 of the inner mid layer.

Abstract: An object of the present invention is to provide a golf ball striking a good balance between flight distance on driver shots and spin rate on approach shots, and excellent in stain resistance and shot feeling. The present invention provides a golf ball comprising a paint film, wherein a base resin of the paint film contains a polyurethane obtained by a reaction between a polyisocyanate composition and a polyol composition containing a urethane polyol having a polyether diol with a number average molecular weight in a range from 800 to 3,000 as a constituent component, and the following requirements are satisfied: Mp?200×X?75 Mp?100 Minm?Moum>40 Moum?Mc<5 Tinm?Toum>Tc>Tp (Tinm×Minm)/(Toum×Moum)>2.0 (Toum×Moum)/(Tc×Mc)<3.0 (Tc×Mc)/(Tp×Mp)>10.

Abstract: A golf ball 2 includes a spherical core 4, a mid layer 6, and a cover 8. The core 4 is obtained by crosslinking a rubber composition. The difference between: a hardness H(5.0) at a point which is located at a distance of 5 mm from the central point of the core 4; and a hardness Ho at the central point is 6.0 or greater. The difference between: a hardness H(12.5) at a point which is located at a distance of 12.5 mm from the central point; and the hardness H(5.0) is 4.0 or less. The difference between a hardness Hs at the surface of the core 4 and the hardness H(12.5) is 10.0 or greater. The difference between the hardness Hs and the hardness Ho is 22.0 or greater. There is no zone in which a hardness decreases from the central point to the surface. A Shore D hardness H3 of the cover is greater than a Shore D hardness H2 of the mid layer.

Abstract: A golf ball 2 includes a core 4, a first mid layer 10, a second mid layer 12, a third mid layer 14, and a cover 8. A volume Vinm and a Shore D hardness Hinm of the first mid layer, a volume Vm and a Shore D hardness Hm of the second mid layer, a volume Voum and a Shore D hardness Houm of the third mid layer, a volume Vc and a Shore D hardness Hc of the cover, and a volume V of an entirety of the ball meet: (a) Hinm<Hm>Houm>Hc, (b) Vinm<Vm>Voum>Vc, (c) Hm?Hc>25, (d) (Vinm+Vm+Voum+Vc)/V<0.40, (e) Vm/Vc>1.50, and (f) (Vm*Hm)/(Vc*Hc)>3.0.

Abstract: A golf ball includes a spherical core and a cover. The core includes an inner core, a mid core, and an outer core. A hardness H(C) is equal to or greater than a hardness H(B). A hardness H(E) is equal to or greater than a hardness H(D). An angle ? is calculated by (Formula 1) from a thickness Y (mm) of the mid core, the hardness H(C), and the hardness H(D). An angle ? is calculated by (Formula 2) from a thickness Z (mm) of the outer core, the hardness H(E), and the hardness H(F). Each of the angle ? and a difference (???) between the angles ? and ? is equal to or greater than 0°. The golf ball has excellent flight performance upon a shot with a driver.

Abstract: A golf ball includes an intermediate layer, a cover, and a paint film, wherein a base resin of the paint film is a polyurethane obtained by a reaction between a polyisocyanate composition and a polyol composition containing a urethane polyol including a polyether diol with a number average molecular weight ranging from 800 to 3000 as a constituent component, and the golf ball satisfies the following requirements; Mp?200×X?75 Mp?100 Mm?Mc>100 Tm>Tc>Tp (Tm×Mm)/(Tc×Mc)>7.5 (Tc×Mc)/(Tp×Mp)>2.4. [Mp, Mm and Mc represent 10% modulus (kgf/cm2) of the paint film, intermediate layer and cover, respectively; Tp, Tm and Tc represent thicknesses (mm) of the paint film, intermediate layer and cover, respectively; and X represents a molar ratio (NCO/OH).

Abstract: [Object] To provide a golf ball that is excellent in high flight distance performance, excellent approach performance, feel at impact. [Solution] A golf ball includes a spherical core, a mid layer, an inner cover, and an outer cover. A hardness Hm of the mid layer is greater than a hardness Hinc of the inner cover which is greater than a hardness Houc of the outer cover. A difference (Hm?Houc) is greater than 25. A volume Vm of the mid layer is greater than a volume Vinc of the inner cover which is greater than a volume Vouc of the outer cover. A ratio [(Vm+Vinc+Vouc)/V] of a sum (Vm+Vinc+Vouc) relative to a volume V of an entirety of the golf ball is less than 0.30. A ratio (Vm/Vouc) is greater than 1.50. A product (Vm*Hm) and a product (Vouc*Houc) meet the following relationship: [(Vm*Hm)/(Vouc*Houc)]>3.0.

Abstract: A golfer classification method in which, in order to classify a golfer based on his/her swing behavior, a first head speed HS1 of a short iron when the golfer hits a golf ball with the short iron is measured; a second head speed HS2 and a blow angle of a long iron when the golfer hits a golf ball with the long iron are measured; the head speed ratio HS2/HS1 is calculated; by comparing the blow angle with a first threshold, the golfer is classified into a down blow group or a non down blow group; and by comparing the head speed ratio HS2/HS1 with a second threshold, the golfer classified into the down blow group is further classified into a first down blow group or a second down blow group. A golf club selection method in which, for the golfer classified by the golfer classification method, a suitable golf club is selected.

Abstract: Provided is a golf ball is excellent in flight distance performance, approach performance, and feel at impact. A ball 2 includes a core 4, a mid layer 6, and a cover 8. The core 4 includes an inner core 10 and an outer core 12. The cover 8 includes an inner layer cover 10 and an outer layer cover 12. An inner core volume Vc, a mid layer volume Vm, a mid layer hardness Hm, an inner layer cover volume Vinc, an inner layer cover hardness Hinc, an outer layer cover volume Vouc, an outer layer cover hardness Houc, and a ball volume V meet the following relational expressions (a) to (g): (a) Vc/V<0.07, (b) Hm>Hinc>Houc, (c) Hm?Houc>25, (d) Vm>Vinc>Vouc, (e) (Vm+Vinc+Vouc)/V<0.30, (f) Vm/Vouc>1.50, and (g) (Vm*Hm)/(Vouc*Houc)>3.0.

Abstract: An object of the present invention is to provide a golf ball striking a good balance between flight distance on driver shots and spin rate on approach shots, and excellent in stain resistance and shot feeling. The present invention provides a golf ball comprising a paint film, wherein a base resin of the paint film contains a polyurethane obtained by a reaction between a polyisocyanate composition and a polyol composition containing a urethane polyol having a polyether diol with a number average molecular weight in a range from 800 to 3,000 as a constituent component, and the following requirements are satisfied: Mp?200×X?75 Mp?100 Minm?Moum>40 Moum?Mc<5 Tinm?Toum>Tc>Tp (Tinm×Minm)/(Toum×Moum)>2.0 (Toum×Moum)/(Tc×Mc)<3.0 (Tc×Mc)/(Tp×Mp)>10.

Abstract: A golf ball includes a core, a mid layer, and a cover. The core includes an inner core, a mid core, and an outer core. The mid layer includes an inner mid layer and an outer mid layer. A hardness H(C) is equal to or greater than a hardness H(B). A hardness H(E) is equal to or greater than a hardness H(D). An angle ? is calculated by (Formula 1). An angle ? is calculated by (Formula 2). The angle ? is 0° or greater. A difference (???) is 0° or greater. A hardness Hm2 of the outer mid layer is less than a hardness Hm1 of the inner mid layer. A hardness Hc of the cover is less than the hardness Hm2.

Abstract: An object of the present is to provide a golf ball having a high spin rate on approach shots under the wet condition and rough condition. The present invention provides a golf ball comprising a golf ball body, and a paint film formed on a surface of the golf ball body, wherein the paint film has a martens hardness of 2.0 mgf/?m2 or less, and a ratio (50% modulus/10% modulus) of 50% modulus to 10% modulus of 1.6 or more.

Abstract: The present invention provides a golf ball comprising a golf ball body with a spherical core having one or more layers, an intermediate layer disposed outside the spherical core and a cover disposed outside the intermediate layer and a paint film formed on a surface of the golf ball body, and having a friction coefficient calculated using a contact force tester of 0.35 or more and 0.60 or less, wherein the golf ball body has specific plurality of dimples on the surface thereof, at least one layer of the spherical core is a rubber layer having a specific hardness distribution, and the rubber layer has a hardness at the outermost point which is greater than a hardness at the innermost point, and the intermediate layer has a slab hardness (Hm) which is greater than a slab hardness (Hc) of the cover.