Abstract: The present invention provides a one-piece golf ball having good durability, good shot feel and excellent flight performance.

Abstract: A method for manufacturing a golf ball, wherein a grinding tool and a ball to be ground are rotated so that their adjacent points move toward opposite directions. A grinding face of the grinding tool is arranged to be Japanese Industrial Standard grain size #80 to 300. The ball is rotated at 100 to 600 mm/s and the grinding tool is rotated at 2400 to 6900 mm/s, and relative velocity of the grinding tool and the ball is 2500 to 7500 mm/s. Flash formed on a parting line of the ball is thereby removed by the grinding face of the rotating grinding tool.

Abstract: The present invention provides a golf ball having excellent controllability at the time of approach and excellent shot feel, wherein spin is easily put on. A cover of the golf ball is composed of a mixture of specific three ionomer resins (1), (2) and (3), wherein the total amount of the resin (1) and resin (2) is not less than 85% by weight and the amount of the resin (3) is not more than 15% by weight in the mixture as a main component, and wherein the amount of the resin (1) is 30 to 82% by weight and the amount of the resin (2) is 3 to 55% by weight in the total of the resin (1) and resin (2) and a stiffness of the cover composition is 1,000 to 2,000 kg/cm.sup.2.

Abstract: The present invention provides a golf ball having excellent shot feel, controllability and durability as well as satisfactory flight performance. A cover of the golf ball is composed of a mixture of specific three resins (1), (2) and (3), wherein the total amount of the resin (1) and resin (2) is 60 to 83% by weight and the amount of the resin (3) is 17 to 40% by weight in the mixture as a main component, and wherein the amount of the resin (1) is 33 to 80% by weight and the amount of the resin (2) is 3 to 50% by weight in the total of the resin (1) and resin (2) and a stiffness of the cover composition is 1000 to 2000 kg/cm.sup.2.

Abstract: A solid golf ball having a solid core, a cover, and dimples formed on the surface of the cover, wherein the dimples satisfy the following equation:(number of dimples).times.(ratio of the area which is not occupied by dimples).div.(Shore D hardness of the cover)=1.4 to 1.9. The cover has a shore D hardness of 55-70 and a flexural modulus of 1,000 to 2,500 kgf/cm2. The core has a deformation amount of 2.4 to 3.5 mm when applying a load of from 10 to 130 kg. The dimples have diameters of 1.0 to 6.5 mm and the number of dimples is within the range of 330-440. The ratio of the area which is not occupied by dimples is within the range of 0.20 to 0.35.

Abstract: The present invention provides a golf ball which has excellent shot feel and good controllability of approach shots, as well as good hit feel when putting. The golf ball comprises a core and a cover covering the core, wherein the cover has a Shore D hardness of 40 to 60,a compression deformation A, formed by applying a load of from 10 kg to 130 kg to the golf ball, is within the range of 2.3 to 3.5 mm,a compression deformation B, formed by applying a load of from 0.2 kg to 5 kg to the golf ball, is within the range of 0.26 to 0.40, anda ratio of compression deformation B to compression deformation A is within the range of 0.10 to 0.15.

Abstract: A solid golf ball having good controllability and long flight distance and having a solid core, a cover covering the core and dimples formed on the surface of the cover, wherein the cover has a Shore D hardness of 52 to 64 and the dimples satisfy the following equation:(Dimple area proportion (%)).times.(Total dimple volume (mm.sup.3)).div.100=220 to 270.

Abstract: A scratch resistant golf ball cover comprising a blend of:(I) an acrylic ionomer or mixture with a methacrylic ionomer having a stiffness modulus of 3000-5000 Kg/cm.sup.2(II) a methacrylic ionomer having a stiffness modulus of 900-2000 Kg/cm.sup.2 neutralized with zinc.

Abstract: A two-piece golf ball which consists essentially of a core and a cover covering the core, wherein said core is made of a rubber composition comprising 100 parts by weight of a base rubber, 20 to 45 parts by weight of a co-crosslinking agent and 0.3 to 5.0 parts by weight of an organic peroxide, a hardness of the core is within a range of 40 to 56 in the vicinity of its center and 70 to 95 in the vicinity of its surface; a difference between a hardness in the vicinity of the surface and that in the vicinity of the center is within a range of 20 to 40; and a compression deformation amount formed between initial loading 10 kg and final loading 130 kg is 3.1 to 4.5 mm; said hardness being measured by means of JIS-C type hardness tester.

Abstract: The present invention provides a golf ball which exhibits a large flying distance and is superior in stability of iron shot and hit feeling.The golf ball comprises a core and a cover for covering the core, the cover comprising two layers of an inner layer cover and an outer layer cover. A stiffness modulus of the inner layer cover is 3,000 to 5,500 kg/cm.sup.2 and that of the outer layer cover being 1,000 to 2,500 kg/cm.sup.2. A thickness of the inner layer cover is 0.5 to 2.5 mm and that of the outer layer being 0.5 to 2.5 mm. A total thickness of the inner layer cover and the outer layer cover is 1.0 to 4.5 mm. A base resin of the inner layer cover contains 5 to 100% by weight of an ionomer neutralized with a zinc ion.

Abstract: The present invention provides a rubber composition having high impact residence, preferred processability and workability which may be used for the manufacture of one-piece solid golf ball, solid core of multi-layered solid golf ball, solid center of thread-wound golf ball, etc. The rubber composition is characterized by that a rubber component is made from a mixture of:(1) 60 to 95 wt % of a polybutadiene containing at least more than 40% of cis-1,4 bond and having a Mooney viscosity [ML.sub.1+4 (100.degree. C.)] of 50 to 70, obtained by using lanthanum rare earth-based catalyst, nickel-based catalyst or cobalt-based catalyst, or a mixture thereof with another polybutadiene obtained by using a catalyst other than the above mentioned one, and(2) 5 to 40 wt % of a polyisoprene containing at least more than 90% of cis-1,4 bond and a Mooney viscosity of 70 to 90.

Abstract: Disclosed is a two-piece golf ball comprising a core made of a rubber composition containing a base rubber, a co-crosslinking agent and an organic peroxide, and a cover. The core of the golf ball contains 20 to 30 parts by weight of the co-crosslinking agent based on 100 parts by weight of the base rubber. A hardness of the core, measured by a JIS-C type hardness tester, is within a range from 70 to 80 at any part from the center to the surface and a difference in hardness at any part is not more than 5. An amount of compression deformation of the core formed between initial loading (10 kg) and final loading (130 kg) is 3.1 to 3.8 mm.

Abstract: In a golf ball according to the present invention, dimples formed on the surface thereof have the same diameter and are classified into first group dimples and second group dimples, and optionally different kinds of dimples within each group, the dimples of one kind differing in depth from the dimples of another kind within that group, each of the first group dimples having a depth substantially the same which is greater than the depth of each of the second group dimples which is also substantially the same for all the second group dimples. The depth of the first group dimple is from 130% to 280% of that of the second group dimple. Further, the number of the first group dimples is from 20% to 80% of the total number of the dimples.

Abstract: The objective of the present invention is to bring hit feeling of two-piece balls closer to that of thread-wound golf balls. The two-piece golf ball of the present invention comprises a core formed from a rubber composition comprising a base rubber, a co-crosslinking agent and an organic peroxide, and a cover covering the core, wherein said core has the following hardness distribution when measured by a JIS-C hardness meter;(1) hardness at a center: 58-73(2) hardness at 5-10 mm from the center: 68-78(3) hardness at 15 mm from the center: 76-88(4) surface hardness: 78-88(in the hardness distribution, hardness (2) is substantially constant being within the above range, of which tolerance is within .+-.3 and the other values satisfy the relation of (1)<(2)<(3).ltoreq.(4) ), a compression deformation of the core is 2.8-3.5 mm when pressurized by an initial load of 10 kg up to a final load of 130 kg and said cover has a thickness of 1.5-1.9 mm.

Abstract: A plurality of small-sized recesses are provided along outer peripheral edges of the openings of semispheric recessed portions in which a golf ball is injection-molded. These small-sized recesses form small-sized positioning juts along the parting line of a golf ball intended to be injection-molded.

Abstract: A two-piece golf having a feel of hitting close to that of a thread-wrapped golf ball. A two-piece golf ball consisting of a core formed of a rubber composition containing a base rubber, a co-crosslinking agent, and an organic peroxide, and a cover covering the core, characterized in that:the core has the following hardness distribution according to JIS - C type hardness meter readings:(1) hardness at center, position A: 58-73(2) hardness at 5 to 10 mm from center, position B: 65-75(3) hardness at 15 mm from center, position C: 74-82(4) surface hardness, position D: 76-84(wherein hardness (2) is generally constant within the range shown, with a variation range of .+-.3, and satisfies the relation (1)<(2)<(3).ltoreq.(4) in other respects), andthe core has a compression deflection of 3.5 to 4.3 mm when a load range of initial 10 kg to final 130 kg is applied, the cover having a thickness of 2.1 to 2.8 mm.

Abstract: The present invention provides a two piece golf ball having excellent hit feeling, which comprises a core and a cover, wherein the core has a deformation (compression deformation) of 3.7 to 4.5 mm caused by applying from 10 kg of an initial load to 130 kg of a final load, and is prepared from a rubber composition comprising 100 parts by weight of a cis-1,4-polybutadiene rubber and 20 to 30% by weight of a metal salt of an unsaturated carboxylic acid, and wherein the cover has a stiffness modulus of 3,700 to 4,500 kg/cm.sup.2 and a thickness of 2.2 to 2.9 mm.

Abstract: The present invention provides a golf ball having excellent impact resilience and good flying performance, which comprises a core and a cover covering the core, wherein the cover contains at least 20 % by weight of a carboxyl-rich ionomer resin prepared by neutralizing 15 to 80 mol % of carboxylic acid groups of an olefinic copolymer containing 16 to 30 % by weight of an alpha, beta-ethylenic unsaturated carboxylic acid with monovalent or divalent metal ions.