Abstract: Golf ball 1 has a core 2, a mid layer 3 and a cover 4. The mid layer 3 is composed of a matrix of which base material is a rubber or a synthetic resin, and solid particles which are dispersed in the matrix. Hardness (Shore D) Hm of the matrix is greater than hardness Hg of the solid particles. Difference between both hardness (Hm?Hg) is 5 or greater. Particle size D of the solid particles is 0.5 mm or greater. A ratio “D/T”, i.e., a ratio of the particle size D to the thickness T of the mid layer is 0.1 or greater. A proportion of the solid particles occupied in the mid layer 3 is 3% by weight or greater and 40% by weight or less. Hardness Hm of the matrix is 30 or greater. Hardness Hg of the solid particle is 40 or less.

Abstract: A cover 6 of a golf ball 2 contains an ionomer resin and a thermoplastic elastomer containing a styrene block. The cover 6 has a thickness of 1.0 mm or greater and 1.8 mm or less, and a hardness of 50 or greater and 60 or less. This golf ball 2 has circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less, and circular dimples having a diameter of less than 3.90 mm. Proportion PN of the number Na of the circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less, to a total number N of the dimples is equal to or greater than 75%. Volume Va of the circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less is greater than 300 mm3. Proportion PV of this volume Va to a total volume V of all the dimples is greater than 95.0%. Occupation ratio of total area of the dimples 8 to the surface area of a phantom sphere is equal to or greater than 75%.

Abstract: A core having a center, and a mantle layer comprising a thermoplastic resin composition is provided. Next, a reinforcing layer including a thermosetting resin composition is formed on the surface of this core to obtain a spherical body 40. Next, this spherical body 40 is covered by two pieces of half shell 46. Next, the spherical body 40 and the half shells 46 are placed into a mold 32. Next, the mold 32 is clamped at a velocity of 0.01 mm/sec or greater and 1.0 mm/sec or less. The thermoplastic resin composition of the half shell 46 is heated while being compressed in the spherical cavity to result in flow. This thermoplastic resin composition is hardened to give a cover having a thickness of 0.1 mm or greater and less than 0.7 mm. The difference (T?Fc) between the molding temperature T and the incipient fluidization temperature Fc of the thermoplastic resin composition of the cover is 0° C. or greater and 30° C. or less.

Abstract: The present invention provides a golf ball having excellent rebound characteristics and flight performance, while maintaining good durability and appearance. The present invention relates to a golf ball comprising a center, an intermediate layer and a cover, the intermediate layer comprises an outermost layer and a second layer adjacent to the underside of the outermost layer, and the cover has many dimples on the surface thereof, wherein the second layer is formed from thermoplastic resin and has a thickness of 0.5 to 2.0 mm, the outermost layer is formed from thermosetting or thermoplastic resin and has a thickness of 1 to 100 ?m, the intermediate layer has depressions on the surface thereof at the position and shape corresponding to the dimples through the cover, and the cover is formed from thermoplastic resin and has a thickness of 0.1 to 0.8 mm in land portion having no dimple.

Abstract: Golf ball 2 has a core 4, a mid layer 6, a reinforcing layer 8 and a cover 10. Base polymer of the mid layer 6 includes an ionomer resin as a principal component. The mid layer 6 has a hardness Hm as measured with a Shore D type hardness scale of equal to or greater than 55. Base polymer of the reinforcing layer 8 is a thermosetting resin. Base polymer of the cover 10 includes a thermoplastic polyurethane elastomer as a principal component. The cover 10 has a nominal thickness Tc of equal to or less than 0.6 mm. The cover 10 has a hardness Hc as measured with a Shore D type hardness scale of equal to or less than 54. Ratio (Tr/Tc) of the thickness Tr of the reinforcing layer to the nominal thickness Tc of the cover is 0.005 or greater and 3.0 or less. This golf ball 2 includes dimples 12 having a depth Dp. Thickness Td of the cover 10 immediately below the deepest site of one or more of the dimples 12 is greater than (Tc?Dp).

Abstract: Golf ball 2 has a core 4, a mid layer 6, a reinforcing layer 8, a cover 10 and dimples 12. Base polymer of the mid layer 6 includes an ionomer resin as a principal component. The reinforcing layer 8 includes a thermosetting resin as a base polymer. Base polymer of the cover 10 includes a thermoplastic polyurethane elastomer as a principal component. The cover 10 has a thickness Tc of equal to or less than 0.6 mm. The cover has a hardness Hc of equal to or less than 54. The cover has a volume V of equal to or less than 3.0 cm3. Product obtained by multiplying the thickness Tc, the hardness Hc and the volume V is equal to or less than 90. Ratio (Dx/Dn), which is a ratio of a mean diameter of the dimples ranking in the top 10% Dx to a mean diameter of the dimples ranking in the bottom 10% Dn when all the dimples are arranged in decreasing order of the diameter is equal to or greater than 1.30. Standard deviation ? of the diameter of all the dimples is equal to or less than 0.52.

Abstract: Golf ball 2 has a spherical core 4, a mid layer 6 covering this core 4, a reinforcing layer 8 covering this mid layer 6, and a cover 10 covering this reinforcing layer 8. Base polymer of this mid layer 6 includes an ionomer resin as a principal component. Base polymer of this cover 10 includes a thermoplastic polyurethane elastomer as a principal component. The cover 10 has a thickness Tc of equal to or less than 0.6 mm. The cover 10 has a hardness Hc as measured with a Shore D type hardness scale of equal to or less than 54. The cover 10 has a volume V of equal to or less than 3.0 cm3. A product obtained by multiplying the thickness Tc, the hardness Hc and the volume V is equal to or less than 90. The reinforcing layer 8 includes a thermosetting resin as a base polymer. The reinforcing layer has a thickness of 3 ?m or greater and 50 ?m or less.

Abstract: Golf ball 2 has a spherical core 4, a mid layer 6 covering this core 4, a reinforcing layer 8 covering this mid layer 6, and a cover 10 covering this reinforcing layer 8. Base polymer of this mid layer 6 includes an ionomer resin as a principal component. Base polymer of the cover 10 includes a thermoplastic polyurethane elastomer as a principal component. The cover 10 has a weight Wc of equal to or less than 3.2 g. The cover 10 has a hardness Hc as measured with a Shore D type hardness scale of equal to or less than 55. A ratio (Hc/Wc) of the hardness Hc to the weight Wc (g) is equal to or greater than 10.0. The reinforcing layer 8 includes a thermosetting resin as a base polymer. The reinforcing layer 8 has a thickness of 3 ?m or greater and 50 ?m or less. The reinforcing layer 8 has a tensile strength of 150 kgf/cm2 or greater and 500 kgf/cm2 or less.

Abstract: Golf ball 2 has a spherical core 4, a mid layer 6 covering this core 4, a reinforcing layer 8 covering this mid layer 6, and a cover 10 covering this reinforcing layer 8. Base polymer of the mid layer 6 includes an ionomer resin as a principal component. The mid layer 6 has a hardness Hm as measured with a Shore D type hardness scale of equal to or greater than 55. Base polymer of the reinforcing layer 8 is a thermosetting resin. Base polymer of the cover 10 includes a thermoplastic polyurethane elastomer as a principal component. The cover 10 has a thickness Tc of equal to or less than 0.6 mm. The cover has a hardness Hc as measured with a Shore D type hardness scale of equal to or less than 54. Ratio (Tr/Tc) of the thickness Tr of the reinforcing layer to the thickness Tc of the cover is 0.005 or greater and 3.0 or less.

Abstract: Dimple 4 has a side wall curved face 8 and an edge neighboring curved face 9. The side wall curved face 8 is situated between a point P4 positioned downward from the dimple edge Ed by the depth of 20% in an in-depth direction and a point P3 positioned downward from the dimple edge Ed by the depth of 50% in an in-depth direction. The edge neighboring curved face 9 is situated between the dimple edge Ed and a point P5 positioned downward from the dimple edge Ed by the depth of 10% in an in-depth direction. Proportion of the number NL of dimples 4 having the diameter of equal to or greater than 3.90 mm occupied in total number N of the dimples is equal to or greater than 75%. Proportion of the number ML of dimples having the ratio (Re/Rw) between a radius of curvature of Re of the edge neighboring curved face 9 and a radius of curvature Rw of the side wall curved face 8 of 0.5 or greater and 1.5 or less of equal to or greater than 75%, having the diameter of equal to or greater than 3.

Abstract: The present invention provides a multi-piece solid golf ball, of which flight performance is improved while maintaining excellent durability and good shot feel. The present invention relates to a multi-piece solid golf ball comprising a core, at least one layer of an inner cover formed on the core and an outer cover covering the inner cover, wherein a surface hardness in JIS-C hardness of the core is higher than a center hardness in JIS-C hardness of the core by not less than 25, a hardness in JIS-C hardness of the inner cover is higher than the surface hardness of the core by less than 15, and a hardness in JIS-C hardness of the outer cover is higher than the hardness of the inner cover by not less than 5.

Abstract: The present invention provides a golf ball having excellent rebound characteristics and excellent flight performance, while maintaining good durability and good appearance. The present invention relates to a golf ball comprising a core composed of a center and at least one intermediate layer formed on the center, and a cover covering the core, and having many dimples on the surface thereof, wherein the outermost layer of the intermediate layer is formed from thermoplastic resin, has a thickness of 0.5 to 3.0 mm, and has depressions on the surface thereof at the position and shape corresponding to the dimples through the cover, and the cover is formed from thermoplastic resin and has a thickness of 0.1 to 0.8 mm in land portion having no dimple.

Abstract: Golf ball 1 has a core 2 and a cover 3. The core 2 is composed of a center 4 and a mid layer 5. Numerous dimples 6 are formed on the surface of the cover 3. Base polymer of the cover 3 includes a mixture of an ionomer resin and a thermoplastic elastomer as a principal component. Shore D hardness of this cover 3 is 55 or greater and 70 or less. A proportion of number of dimples 6 having the tilt angle ? of from the position, which is 20% downward from the dimple edge in an in-depth direction, down to the position, which is 50% downward from the dimple edge, of 65° or greater and 85° or less occupied in total number of dimples is equal to or greater than 20%.

Abstract: A cover 6 of a golf ball 2 contains an ionomer resin and a thermoplastic elastomer containing a styrene block. The cover 6 has a thickness of 1.0 mm or greater and 1.8 mm or less, and a hardness of 50 or greater and 60 or less. This golf ball 2 has circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less, and circular dimples having a diameter of less than 3.90 mm. Proportion PN of the number Na of the circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less, to a total number N of the dimples is equal to or greater than 75%. Volume Va of the circular dimples having a diameter of 3.90 mm or greater and 4.80 mm or less is greater than 300 mm3. Proportion PV of this volume Va to a total volume V of all the dimples is greater than 95.0%. Occupation ratio of total area of the dimples 8 to the surface area of a phantom sphere is equal to or greater than 75%.

Abstract: Golf ball 1 includes a core 2 and a cover 3. The core 2 has two layers including a center 4 and a mid layer 5. The mid layer 5 is formed by covering the center 4 with two half shells comprising a rubber composition, and by compression and heating of the center 4 and half shells in a mold. The rubber composition contains solid particles dispersed therein. The solid particles have a ratio “D/T”, i.e., a ratio of the particle size D to the thickness of the mid layer T, of equal to or greater than 0.3. Upon molding, the solid particles inhibit the center 4 to approach a cavity face. Accordingly, deviation of mass of the mid layer 5 can be suppressed. The solid particles have a ratio “W/T”, i.e., a ratio of the radial width W thereof to the thickness of the mid layer T, of from 0.3 to 1.0.

Abstract: A golf ball comprises a large number of dimples (4) on a surface thereof. The dimple (4) includes a first curved surface (7) provided from a position (P2) placed downward by 85% of a depth to a position (P1) placed downward by 100% of the depth in a direction of the depth from an edge (E) and a second curved surface (8) provided from a position (P5) placed downward by 20% of the depth to a position (P3) placed downward by 50% of the depth in the direction of the depth from the edge (E). A percentage, to a total number of the dimples, of a number of the dimples in which a ratio (R1/R2) of a radius of curvature (R1) of the first curved surface (7) to a radius of curvature (R2) of the second curved surface (8) is 5 to 55 is 20% or more. A third curved surface (9) is present between the first curved surface (7) and the second curved surface (8). A fourth curved surface (10) is present between the second curved surface (8) and the edge (E).

Abstract: A golf ball 2 has a core, a mid layer and a cover. This mid layer comprises 10 parts by weight or greater and 70 parts by weight or less of a thermoplastic elastomer containing a styrene block having a material hardness of less than 10, and 30 parts by weight or greater and 90 parts by weight or less of an ethylene-(meth)acrylic acid copolymer based ionomer resin having a material hardness of 50 or greater and 70 or less. Hardness of this mid layer is less than 40, and the thickness is equal to or less than 1.2 mm. This golf ball 2 has seven kinds of dimples (Ato G), each having a different diameter. When all the dimples are arranged in decreasing order of the diameter Di, ratio (Dx/Dn) of the mean diameter Dx of the dimples ranking in the top 10% to the mean diameter Dn of the dimples ranking in the bottom 10% is equal to or greater than 1.30. Standard deviation ? of diameters of all the dimples is equal to or less than 0.

Abstract: A mold comprises a spherical cavity, a support pin capable of being moved forward and backward with respect to the cavity, and a vent pin (8). The vent pin (8) includes two slits (S), an annular groove (20) and a vertical groove (22). An upper end (24) of the slit (S) is opened toward the cavity. A lower end (26) of the slit (S) is opened toward the annular groove (20). The annular groove (20) is coupled to the vertical groove (22). The lower end of the vertical groove (22) is opened toward air. A width (W) of the slit (S) is preferably equal to or greater than 1 ?m, is more preferably equal to or greater than 3 ?m, and is particularly preferably equal to or greater than 5 ?m. A depth (D) of the slit (S) is preferably equal to or greater than 10% of a diameter (?), is more preferably equal to or greater than 15% of the diameter (?), and is particularly preferably equal to or greater than 20% of the diameter (?). It is preferable that the same slit (3) should be formed on the support pin.

Abstract: A golf ball 2 has dimples A having a diameter of 4.65 mm, dimples B having a diameter of 4.45 mm, dimples C having a diameter of 4.25 mm, dimples D having a diameter of 4.05 mm, dimples E having a diameter of 3.95 mm, dimples F having a diameter of 2.80 mm, and dimples G having a diameter of 2.65 mm. When all the dimples 8 are arranged in decreasing order of the diameter Di, the mean diameter of the dimples 8 ranking in the top 10% is represented by Dx (mm), and the mean diameter of the dimples 8 ranking in the bottom 10% is represented by Dn (mm). Dx/Dn is equal to or greater than 1.30. Standard deviation ? of diameters of all the dimples 8 is equal to or less than 0.52. Mean value of the diameters of all the dimples 8 is equal to or greater than 4.00 mm.

Abstract: A golf ball 1 includes an A dimple having a diameter of 4.35 mm, a B dimple having a diameter of 3.9 mm, a C dimple having a diameter of 3.4 mm, and a D dimple having a diameter of 3.2 mm. All the dimples have circular plane shapes. A ratio PN of a number Na of the circular dimples having the diameters of 3.9 mm to 4.8 mm to a total number N of the dimples is 75% or more. A volume Va of the circular dimples having the diameters of 3.9 mm to 4.8 mm is 200 mm3 to 300 mm3. A ratio PV of the volume Va to a total volume V of all the dimples is 70% to 95%. A surface area occupation ratio Y of all the dimples is 75% or more.