Abstract: A golf ball 2 includes a spherical core 4 and a cover 6 covering the core 4. The cover 6 includes an inner cover 8 and an outer cover 10 positioned outside the inner cover 8. When distances (%) from a central point of the core 4 to nine points and hardnesses at the nine points, which nine points are obtained by dividing a region from the central point 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 0.95 or greater. A hardness of an innermost layer of the cover 6 is greater than a surface hardness of the core 4. Preferably, the core is obtained by a rubber composition being crosslinked. The rubber composition includes an acid and/or a salt (d).

Abstract: A first golf ball 2 includes a core 4, a mid-layer 6, and a cover 8. The core 4 includes a center 10 and an envelope layer 12. The mid-layer 6 includes a metal ion source (C) that can neutralize an ionomer resin. The mid-layer 6 has a melt flow rate (at 190° C. and 2.16 kg) of 4 g/10 minute or greater. The difference (H3?H1) between the JIS-C hardness H3 of the cover 8 and the JIS-C central hardness H1 of the center 10 is equal to or greater than 45. A second golf ball 22 includes a core 24, a mid-layer 28, and a cover 30. The mid-layer 28 has a melt flow rate (at 190° C. and 2.16 kg) of 4 g/10 minute or greater. Preferably, the mid-layer 28 includes a high melt viscosity resin (A), a low melt viscosity ionomer resin (B), and a metal ion source (C1).

Abstract: A golf ball 2 includes a spherical core 4, a mid layer 6 positioned outside the core 4, and a cover 8 positioned outside the mid layer 6. The core 4 includes a spherical center 10 and an envelope layer 12 positioned outside the center 10. The center 10 has a diameter of 1 mm or greater and 15 mm or less. The center 10 has a JIS-C hardness H1, at its central point, of 20 or greater and 50 or less. The difference (H4?H3) between the JIS-C hardness H4 of the core 4 at its surface and the JIS-C hardness H3 of the envelope layer 12 at its innermost portion is equal to or greater than 10. The cover 8 has a flexural modulus of 300 MPa or greater and 1000 MPa or less, and has a tensile modulus of 400 MPa or greater and 1500 MPa or less.

Abstract: A golf ball 2 includes a spherical core 4, a cover 6 and a paint layer 8. The core 4 includes a spherical center 10 and a mid layer 12. The cover 6 is formed from a resin composition that includes a base resin and a fluorescent pigment. The paint layer 8 is formed from a resin composition that includes a base resin and a light-collecting fluorescent dye. A product of an amount of the light-collecting fluorescent dye per 100 parts by weight of the base resin in the paint layer 8 and a thickness (mm) of the paint layer 8 is higher than 5.0×10?5 and lower than 2.0×10?3.

Abstract: A golf ball 2 includes a core 4, a cover 6, and a paint layer 8. The golf ball 2 has numerous dimples 10 on the surface thereof. The cover 6 is formed of a resin composition including thermoplastic polyurethane (A) and a polyisocyanate mixture (B). The polyisocyanate mixture (B) includes a polyisocyanate compound (B1) having two or more isocyanate groups or a urethane prepolymer (B2) having two or more isocyanate groups. The cover 6 has a hardness of 30 or greater and 55 or less. The cover 6 has a thickness of 1.0 mm or greater and 2.0 mm or less. The ratio of the total volume of all the dimples 10 to the surface area of a phantom sphere of the golf ball is less than 75%. The dimples 10 have a curvature radius at the edge thereof in a range of 0.1 mm to 10 mm.

Abstract: 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 6 includes a benzotriazole based ultraviolet ray absorbing agent, a hindered amine light stabilizer and a hindered phenol heat resistance stabilizer. Provided that the molar concentration of the benzotriazole based ultraviolet ray absorbing agent is defined as A; the molar concentration of the hindered amine light stabilizer is defined as B; and the molar concentration of the hindered phenol heat resistance stabilizer is defined as C, the molar ratio (B/A) is 0.01 or greater and 0.5 or less, and the molar ratio [(B+C)/A] is 0.1 or greater and 1.5 or less. Preferably, the hindered amine light stabilizer does not have a hindered phenol group in the molecule. Preferably, the principal component of the elastomer is a reaction product of MDI and polyether polyol.

Abstract: In the present invention, unlike a conventional circuit, discrimination is not made by integrating a logical code that includes “0” and “1” to some extent and produced from a random code, but repetition of an identical pattern of a well-known preamble signal added to a head portion of a signal is discriminated when a bit-rate of the signal is changed. More specifically, the repetition of the identical pattern is converted into a consecutive identical signal to generate the consecutive identical signal (having a length of tens bits to thousands bits). Although the consecutive identical signal is longer than a same-code continuation length included in the signal, and is shorter than a time constant necessary to the conventional circuit by about one to three digits. Therefore, an integration time can be shortened to the same degree as the generated consecutive identical signal length, and the bit-rate can be discriminated at high speed within a preamble signal receiving time.

Abstract: A golf ball 2 includes a spherical core 4, a mid layer 6 positioned outside the core 4, and a cover 8 positioned outside the mid layer 6. The core 4 includes a spherical center 10 and an envelope layer 12 positioned outside the center 10. The center 10 has a diameter of 1 mm or greater and 15 mm or less. The center 10 has a JIS-C hardness H1, at its central point, of 20 or greater and 50 or less. The difference (H4?H3) between the JIS-C hardness H4 of the core 4 at its surface and the JIS-C hardness H3 of the envelope layer 12 at its innermost portion is equal to or greater than 10. The cover 8 has a flexural modulus of 300 MPa or greater and 1000 MPa or less, and has a tensile modulus of 400 MPa or greater and 1500 MPa or less.

Abstract: A golf ball 2 includes a spherical core 4, a mid layer 6 positioned outside the core 4, and a cover 8 positioned outside the mid layer 6. The core 4 includes a spherical center 10 and an envelope layer 12 positioned outside the center 10. The center 10 has a diameter of 1 mm or greater and 15 mm or less. The center 10 has a JIS-C hardness H1, at its central point, of 20 or greater and 50 or less. The difference (H4?H3) between the JIS-C hardness H4 of the core 4 at its surface and the JIS-C hardness H3 of the envelope layer 12 at its innermost portion is equal to or greater than 10. The cover 8 has a flexural modulus of 300 MPa or greater and 1000 MPa or less, and has a tensile modulus of 400 MPa or greater and 1500 MPa or less.

Abstract: A golf ball 2 includes a spherical core 4 and a cover 6 covering the core 4. The cover 6 includes an inner cover 8 and an outer cover 10 positioned outside the inner cover 8. The core 4 is obtained by a rubber composition being crosslinked. The rubber composition includes a base rubber (a), a co-crosslinking agent (b), a crosslinking initiator (c), and a carboxylate (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. The amount of the carboxylate (d) is equal to or greater than 1 parts by weight but less than 40 parts by weight per 100 parts by weight of the base rubber (a). A hardness of an innermost layer of the cover is greater than a surface hardness of the core.

Abstract: A golf ball 2 includes a spherical core 4 and a cover 6 covering the core 4 and including an inner cover 8 and an outer cover 10 positioned outside the inner cover 8. The core 4 is obtained by crosslinking a rubber composition. The rubber composition includes a base rubber (a), a co-crosslinking agent (b), a crosslinking initiator (c), and a carboxylate (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. The amount of the carboxylate (d) is equal to or greater than 1 parts by weight but less than 40 parts by weight per 100 parts by weight of the base rubber (a). A hardness of an innermost layer of the cover is equal to or less than a surface hardness of the core.

Abstract: A golf ball 2 has, on a surface thereof, a plurality of types of dimples 8 having different diameters from each other. A standard deviation ye of the volumes of all the dimples 8 is equal to or less than 0.095 mm3. The ratio (V?/D?) of the standard deviation V? to a standard deviation D? of the diameters of all the dimples 8 is equal to or less than 0.35. Preferably, the shape of each dimple 8 is a portion of a spherical surface. The standard deviation V? is preferably equal to or less than 0.087 mm3. The ratio (V?/D?) is preferably equal to or less than 0.29.

Abstract: 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 6 includes one or more kinds of ultraviolet ray absorbing agents. The paint layer 12 includes one or more kinds of ultraviolet ray absorbing agents. There are one or more kinds of ultraviolet ray absorbing agents (common ultraviolet ray absorbing agent) included in the cover 6 and the paint layer 12. The cover 6 includes the common ultraviolet ray absorbing agent in an amount of A parts by weight per 100 parts by weight of the base polymer, and the paint layer 12 includes the common ultraviolet ray absorbing agent in an amount of B parts by weight per 100 parts by weight of the resin component, with the ratio (A/B) being preferably 0.1 or greater and 10 or less. Preferably, the thermoplastic polyurethane elastomer is an MDI based polyurethane elastomer.

Abstract: The surface of a golf ball 2 is divided by four comparting great circles CG into six spherical quadrangles Ss and eight spherical triangles St. The eight spherical triangles St are composed of four first spherical triangles St1 and four second spherical triangles St2. Dimple patterns of the six spherical quadrangles Ss are the same. Dimple patterns of the four first spherical triangles St1 are the same. Dimple patterns of the four second spherical triangles St2 are the same. The dimple pattern of each first spherical triangle St1 is different from the dimple pattern of each second spherical triangle St2. The comparting great circles CG are obtained by projecting the 24 sides of a cuboctahedron inscribed in a phantom sphere of the golf ball 2 on the surface of the phantom sphere.

Abstract: A golf ball 2 includes a core 4, an envelope layer 6, a mid layer 8 and a cover 10. A thickness Tm of the mid layer 8 is equal to or less than 1.0 mm. A thickness Tc of the cover 10 is less than 0.6 mm. The sum of the thicknesses Tm and Tc is equal to or less than 1.5 mm. A hardness Hc of the cover 10 is less than 40. The hardness Hs, the hardness Hm, and the hardness Hc satisfy the following formula (1). Hs>Hc>Hm??(1) The base material of the envelope layer 6 is ionomer resin. The base material of the mid layer 8 is polyurethane. The base material of the cover 10 is polyurethane.

Abstract: A golf ball 2 has a hollow center 8, a mid layer 10, an inner cover 12 and an outer cover 14. The center 8 is formed by crosslinking a rubber composition. The rubber composition contains a natural rubber as a base polymer. The rubber composition contains sulfur. The mid layer 10 is formed by crosslinking a rubber composition. This rubber composition includes butadiene as a principal component of the base polymer. The center 8 has an inside diameter of 2 mm or greater and 13 mm or less. The center 8 has an outside diameter of 5 mm or greater and 15 mm or less. The center 8 has a surface JIS-C hardness H2 of 25 or greater and 55 or less. A difference (H4?H3) between a surface JIS-C hardness H4 of the mid layer 10 and a JIS-C hardness H3 of an innermost part of the mid layer is equal to or greater than 10.

Abstract: A golf ball 2 includes a core 4, an envelope layer 6 positioned outside the core 4, a mid layer 8 positioned outside the envelope layer 6, and a cover 10 positioned outside the mid layer 8. The core 4 includes a spherical center 12 and a core outer layer 14 positioned outside the center 12. The center 12 has a diameter of 1 mm or greater and 15 mm or less. The difference (H4?H3) between the JIS-C hardness H4 of the core 4 at its surface and the JIS-C hardness H3 of the core outer layer 14 at its innermost portion is equal to or greater than 10. The cover 10 has a Shore D hardness H7 less than 40. The Shore D hardnesses H5, H6 and H7 of the envelope layer 6, the mid layer 8, and the cover 10 satisfy that H5>H6?H7.

Abstract: A golf ball 2 includes a core 4, a mid layer 6, and a cover 8. The difference between: a hardness H(5.0) at a point 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 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. In the core 4, there is no zone in which a hardness decreases from the central point to the surface. A hardness H3 of the cover 8 is greater than a hardness H2 of the mid layer 6. The cover 8 is formed from a resin composition containing a polyamide copolymer including a polymerized fatty acid (a-1), sebacic acid and/or azelaic acid (a-2), and a polyamine component (a-3).

Abstract: A golf ball 2 has, on a surface thereof, a plurality of types of dimples 10 having different diameters from each other. The standard deviation of the curvature radii of cross sections of all the dimples 10 is 0.90 mm or less. The average of the curvature radii of the cross sections of all the dimples 10 is 20% or greater but 40% or less of the diameter of the golf ball. The sum of the volumes of all the dimples is 300 mm3 or greater but 370 mm3 or less. The average of the diameters of all the dimples is 3.5 mm or greater but 4.5 mm or less. The ratio of the sum of the areas of all the dimples to the surface area of a phantom sphere of the golf ball is 75% or greater but 95% or less.

Abstract: A golf ball 2 has, on a surface thereof, a plurality of types of dimples 8 having different diameters from each other. The standard deviation of the curvature radii of cross sections of all the dimples 8 is 0.90 mm or less. The average of the curvature radii of the cross sections of all the dimples 8 is greater than 40% but 50% or less of the diameter of the golf ball 2. The sum of the volumes of all the dimples 8 is 280 mm3 or greater but 350 mm3 or less. The average of the diameters of all the dimples 8 is 3.9 mm or greater but 4.5 mm or less. The ratio of the sum of the areas of all the dimples 8 to the surface area of a phantom sphere of the golf ball 2 is 75% or greater but 95% or less.