Abstract: The present invention provides a solid golf ball having exceptional rebound characteristics and flight performance, as well as good shot feel. The present invention relates to a solid golf ball comprising at least one layer of a core, and at least one layer of a cover formed on the core, wherein at least one of the layers of the core is formed by vulcanizing and press-molding a rubber composition comprising a base rubber, co-crosslinking agent, organic peroxide, filler and specific organic sulfur compound which contains substituent groups having a substituent constant of not less than 1.42.

Abstract: A golf ball (1) comprises a center (2), a rubber thread layer (3) and a cover (4). The rubber thread layer (3) is formed by winding a drawn rubber thread around the center (2). The rubber thread is obtained by crosslinking a rubber with a sulfur and a vulcanization accelerator. The rubber contains 60% by weight or more of synthetic polyisoprene having a trans 1,4 bond ratio of 2% to 4%. Moreover, the vulcanization accelerator contains 66% by weight or more of a nonbasic vulcanization accelerator and 10% by weight to 30% by weight of an amine type vulcanization accelerator. A weight ratio of an amount of the sulfur to a total amount of the vulcanization accelerator is 0.8/1 to 8/1. The rubber thread rarely causes crystallization during drawing and a thermal deterioration when molding the cover. The golf ball (1) has an excellent resilience performance.

Abstract: A golf ball having a coating layer which is excellent in resistance to impact, scuffing and abrasion without increasing the thickness of the layer. The coating layer has a hardness of 21 to 60 N/mm2, which is calculated by the following expression (1): Hardness=(test load)/{26.43×(penetration depth (mm))2}  (1) wherein the test load is 3 mN.

Abstract: A golf ball is composed of a core (1) and a cover (3) covering the core (1). The core (1) is composed of a cross-linked rubber whose Young's modulus lies in the range of 3O Mpa to 100 Mpa both inclusive and whose loss factor lies in the range of 0.01 to 0.45 both inclusive, when the Young's modulus and the loss factor are measured by a split Hopkinson's bar tester whose impact bar has a collision speed of 14.0 m/sec.

Abstract: In order to improve smoothness and contamination resistance of the surface of a golf ball while impact resistance of a coating film is preserved, a painted golf ball constituted of a body and a coating film formed on the body is fabricated by using urethane resin-based paint, acrylic resin-based paint or epoxy resin-based paint for the coating film, the paint containing modified polysiloxane having at least one hydroxyl or carboxyl group in one end of a polysiloxane chain at a ratio of 0.1 to 10% by weight relative to a resin component of the paint, and the modified polysiloxane having a molecular weight of 700 to 7000.

Abstract: A golf ball (1) comprises a center (2), a rubber thread layer (3) and a cover (4). The rubber thread layer (3) is formed by winding a drawn rubber thread around the center (2). The rubber thread is obtained by crosslinking a rubber with a sulfur and a vulcanization accelerator. The rubber contains 60% by weight or more of synthetic polyisoprene having a trans 1,4 bond ratio of 2% to 4%. Moreover, the vulcanization accelerator contains 66% by weight or more of a nonbasic vulcanization accelerator and 10% by weight to 30% by weight of an amine type vulcanization accelerator. A weight ratio of an amount of the sulfur to a total amount of the vulcanization accelerator is 0.8/1 to 8/1. The rubber thread rarely causes crystallization during drawing and a thermal deterioration when molding the cover. The golf ball (1) has an excellent resilience performance.

Abstract: A golf ball (1) comprises a center (2), a rubber thread layer (3) and a cover (4). The rubber thread layer (3) is formed by winding a drawn rubber thread around the center (2). The rubber thread is obtained by cutting a crosslinked rubber sheet. A hysteresis loss of the crosslinked rubber sheet is 30% or less with an extension range of 0% to 1000%. Moreover, a universal hardness of a DIN standard measured with a load of 3 mN is 1.5 N/mm2 to 5 N/mm2 when a whole length is increased up to 1000%. The rubber thread is broken with difficulty during drawing. The golf ball (1) has an excellent resilience performance.

Abstract: In a viscoelastic characteristic value-measuring apparatus, using a split Hopkinson's bar, a first strain gauge (7) and a second strain gauge (9) are installed are installed on an input bar (3) which is hit with a impact bar. A third strain gauge (11) and a fourth strain gauge (13) are installed on an output bar (5) which is connected with the input bar (3) through a specimen (20) put between the input bar (3) and the output bar (5). The length of the input bar is set to not less than 1000 mm nor more than 2500 mm. The length of said output bar is set to not less than 700 mm nor more than 2200 mm. The propagation speed of a strain in the input bar and the output bar is set to not less than 1200 m/s nor more than 1800 m/s.

Abstract: A thread rubber exhibiting good impact resilience and reduced in breakage during a winding step, and a golf ball employing such thread rubber are provided. The thread rubber composition for a golf ball has 0.5-7.0 parts by weight of sulfur and 0.5-5.0 parts by weight of vulcanization accelerator blended with respect to 100 parts by weight of a rubber component including either one of polyisoprene rubber, natural rubber and polybutadiene rubber, or a mixture thereof. The rubber component has a cis-1, 4 bond content of from 90.0% to 93.8%. The blended amount of the sulfur is made greater than the blended amount of the vulcanization accelerator.

Abstract: A thread rubber exhibiting good impact resilience in an elongated state, and a golf ball using such thread rubber are provided. The vulcanized thread rubber composition is obtained by vulcanizing a thread rubber composition including at least 50 wt % of polyisoprene rubber having a cis 1, 4 bond content of 80-95% and a trans 1, 4 bond content of 2-4% within a rubber component. In the vulcanizate, a ratio of a crosslinked density of polysulfide bonds with respect to a total crosslinked density is more than 70%. The golf ball is made using this vulcanized thread rubber composition.

Abstract: The present invention provides a coating material for a golf ball. The coating material comprises a polyol(1) containing a urethane polyol and a polyisocyanate. The urethane polyol is produced by the reaction between a diisocyanate and a polyol(2) containing as an essential ingredient a diol and a triol at the triol/diol equivalent ratio of 0.2 to 3. The urethane polyol has Mw of 4000 to less than 10000. The coating material is dryable in a short time at low temperatures and forms a coating layer having excellent resistance to scuffing and adhesion to a golf ball main body.

Abstract: A manufacturing method according to the present invention comprises the steps of (a) feeding a rubber composition (8) between a heat roller (3) and a belt (7) pressed against the heat roller (3) and pressurizing and crosslinking the rubber composition (8) by means of the heat roller (3) and the belt (7), thereby obtaining a crosslinked sheet material, and (b) cutting the crosslinked sheet material to obtain the rubber thread. A pressure to be applied to the rubber composition (8) at the crosslinking step is 0.03 MPa to 1 MPa. The rubber composition (8) fed at the crosslinking step is previously formed into a sheet by extrusion. Since a dry blend method is employed for the manufacturing method, a great workability can be obtained. The rubber thread obtained by the manufacturing method is easily stretched and is broken with difficulty during the stretch.

Abstract: The present invention provides a solid golf ball which attains long flying distance and is superior in hit feeling and durability. The present invention provides a solid golf ball in which at least a portion thereof is made of rubber, wherein the rubber portion is a crosslinked, molded rubber composition comprising a base rubber, a co-crosslinking agent and peroxides, the base rubber comprising a polybutadiene modified with a tin compound and having a cis content of 40% or more.

Abstract: The present invention provides a coating material for a golf ball. The coating material comprises a polyol(1) containing a urethane polyol and a polyisocyanate. The urethane polyol is produced by the reaction between a diisocyanate and a polyol(2) containing as an essential ingredient a diol and a triol at the triol/diol equivalent ratio of 0.2 to 3. The urethane polyol has Mw of 4000 to less than 10000. The coating material is dryable in a short time at low temperatures and forms a coating layer having excellent resistance to scuffing and adhesion to a golf ball main body.

Abstract: A method of producing a rubber thread for a golf ball comprises (a) an extruding process of extruding a rubber composition in the shape of a sheet by using an extruder (2) to obtain a sheet material (6); (b) a rolling process of rolling the sheet material (6) to make it thin to obtain a thin sheet material (10); (c) a cross-linking process of cross-linking the thin sheet material (10) to obtain a cross-linked sheet material; and (d) a cutting process of cutting the cross-linked sheet material to obtain a rubber thread. The rolling process is performed successively to the extruding process. The thickness t1 of the sheet material (6) obtained in the extruding process is set to the range of 1 mm to 8 mm both inclusive. The thickness t2 of the thin sheet material (10) obtained in the rolling process is set to the range of 0.3 mm to 0.6 mm both inclusive.

Abstract: A hollow golf ball comprising a hollow core and a cover layer that possesses good shot feel, an increased moment of inertia, and a high launch angle at the time of hitting. Immediately after impact, the hollow golf ball has a small spin amount. The specific hollow core reduces the rate of spin dumping between the ascending and descending of the ball, which results in increased flight distance. The hollow golf ball has a hollow core and a cover layer formed on the core, wherein the hollow core is composed of a hollow portion having a diameter of 5 to 30 mm and a core outer layer portion surrounding said hollow portion.

Abstract: A hollow golf ball having good shot feel at the time of hitting, while maintaining excellent flight performance, wherein the hollow golf ball has a hollow core having a hollow portion and one or more hollow core outer layers formed thereon, the hollow core outer layers having a core composition containing rubber, a resin or a mixture thereof, and a cover formed on the hollow core, and wherein the hollow portion has a diameter of 5 to 25 mm, the hollow core outer layer has a surface hardness of 71 to 91 in JIS-C hardness and a deformation amount of 2.0 to 3.5 mm when applying from an initial load of 10 kgf to a final load of 130 kgf on the core.

Abstract: A method of producing a hollow golf ball having excellent durability, which comprises a hollow portion with perfect spherical shape. The method of making a hollow golf ball having a hollow core composed of a hollow center having a hollow portion and optionally one or more intermediate core layers formed on the hollow center, and a cover formed on the hollow core, includes the steps of (a) preparing a rubber composition for the hollow center, (b) molding the rubber composition for the hollow center into a vulcanized semi-spherical half-shell, and (c) bonding the two vulcanized semi-spherical half-shells by placing an unvulcanized adhesive rubber composition between bonding surfaces of the two vulcanized semi-spherical half-shells, and vulcanizing it in a mold to form the hollow center, wherein the unvulcanized rubber composition has a t.sub.90 time of 5 to 20 minutes, the t.sub.

Abstract: The present invention provides a method for the production of a hollow golf ball, which has a perfect spherical hollow portion and possesses excellent durability and good shot feel at the time of hitting, without adversely affecting a good rebound performance. The present invention provides a method for producing a hollow golf ball comprising a hollow core (5) having a hollow center (2) and a hollow portion (1) and, optionally, at least one intermediate core layer (3) formed on the hollow center (2), and a cover (4) formed on the hollow core (5), wherein the step of producing the hollow center (2) comprises:(i) preparing a rubber composition for hollow center;(ii) forming a bowl-shaped half-shell from the rubber composition for the hollow center and vulcanizing only the inside of the half-shell; and(iii) bonding two of the half-shells together to form a complete sphere body which is then vulcanized to obtain the hollow center (2).

Abstract: The present invention provides a coating material for golf ball. The coating material comprises: polyol containing urethane polyol as a chief material; and polyisocyanate as a curing agent. An equivalent ratio of isocyanate groups of the polyisocyanate with respect to hydroxyl groups of the polyol is 0.5 to 2.0. The urethane polyol has a hydroxyl value of 55 to 130 mgKOH/g, and weight-average molecular weight of 4000 to 9000.