Abstract: A golf ball having a very low compression and a high COR is disclosed herein. The core preferably comprises a single neodymium-catalyzed polybutadiene, and has a diameter ranging from 1.575 inch to 1.62 inch with a compression ranging from 20 to 45. The cover preferably has a thickness ranging from 0.038 inch to 0.045 inch, and a Shore D hardness ranging from 50 to 58. The golf ball preferably has a coefficient of restitution of at least 0.780, and a compression ranging from 35 to 50.

Abstract: An object of the present invention is to provide a resin composition for the golf ball that suppresses the bleed out of the low molecular weight material component, as well as improves the fluidity and repulsion performance. The present invention provides a golf ball forming resin composition comprising as a resin component, (A) a high melt viscosity resin; (B) a low melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 1 Pa·s to 10 Pa·s measured by a brookfield viscometer, in a ratio of (A) the high melt viscosity resin/(B) the low melt viscosity ionomer resin being 55 mass % to 99 mass %/45 mass % to 1 mass %; and (C) a metal ion source capable of neutralizing carboxyl groups of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin, in an amount of from 0.1 part to 10 parts with respect to 100 parts by mass of a sum of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin.

Abstract: An object of the present invention is to provide a golf ball excellent in fluidity, adhesion of the paint film, and repulsion. Another object of the present invention is to provide a golf ball which is excellent in durability and low-temperature durability.

Abstract: A low compression, resilient golf ball having a center including a material formed from the conversion reaction of sufficient amounts of polybutadiene, a free radical source, and a cis-to-trans catalyst to convert a portion of cis-isomer to trans-isomer in the polybutadiene, wherein said material has an amount of trans-isomer greater than the amount of trans-isomer present before the conversion reaction, and wherein the reaction product includes low levels or substantially no antioxidant.

Abstract: The present invention is directed to a golf ball having at least one layer formed from a rubber composition comprising a base rubber, at least 0.05 parts by weight of a free radical initiator, per 100 parts of the base rubber, and at least 0.1 parts by weight of a benzoquinone, per 100 parts of the base rubber. The rubber composition may be present in any one or more of a core layer, a cover layer, or an intermediate layer.

Abstract: The invention provides a golf ball material composed of (i) a non-ionomeric thermoplastic resin, (ii) an ionomeric resin and/or an acid-containing polymer which is the base resin of an ionomeric resin, and (iii) at least one compound selected from among N,N-dialkylaminoalkyl(meth)acrylamide, N,N-dialkylaminoalkyl(meth)acrylate and derivatives thereof. Methods for preparing such a material, and a golf ball which includes as a component therein a molded part made of the golf ball material are also provided. The golf ball material has a good thermal stability, flow and processability, and can thus be used to obtain high-performance golf balls having an excellent rebound resilience, an outstanding durability and a good flexibility.

Abstract: A golf ball has a core, a conductive paint layer coated on the surface of the core, a reflective layer formed by electroplating a bright thin surface metal layer on the conductive paint layer and a transparent layer formed on the reflective layer. When the golf ball is hit, the light projection to the golf ball is reflected by the reflective layer to look more brilliant. The reflective layer is protected by the transparent layer without damaging after the golf ball is hit. It also makes discerning of the flying distance and dropping location of the golf ball easier.

Abstract: A high impact game ball with a core structure founded on a spherical member, a spherical casing concentrically disposed relative to the spherical member, at least one surface deviation disposed relative to the spherical member of the core structure, and at least one corresponding surface deviation disposed relative to the spherical casing in a mating relationship with the at least one surface deviation of the spherical member. A switching arrangement can be embedded in the spherical member for causing a response to be exhibited based on the occurrence of an activation condition, such as an impact or a remote activation signal. A plurality of positioning stays can project from the spherical member to ensure a concentric relationship relative to the spherical casing.

Abstract: Disclosed herein are a novel thermoplastic material and a golf ball utilizing the thermoplastic material of the invention. The golf ball (10) preferably comprises a core (12), a cover (16) and, optionally, a boundary layer (14). At least one of the core (12), cover (16) or boundary layer (14) of the golf ball (10) comprises a thermoplastic material according to the invention. A thermoplastic material of the invention comprises a partially to highly neutralized blend of an acid copolymer, a copolymer comprising a metallocene-catalyzed alpha-olefin and a softening comonomer, and a fatty acid or fatty acid salt.

Abstract: The present invention provides a golf ball material which is a thermoplastic ionomer blend composition of an acid-containing ethylene-based terpolymer having a weight-average molecular weight Mw of at least about 100,000, an acid-containing ethylene-based copolymer and/or terpolymer having a Mw of about 1,500 to about 95,000, and a low-molecular-weight acid-containing compound having a molecular weight of up to about 1,000, at least some portion of which composition is neutralized. The golf ball material is soft and resilient, and has a good durability and improved moldability.

Abstract: Disclosed embodiments concern using at least one triazine, typically an amine or polyamine triazine (referred to as amino triazines), in combination with at least one ionomer or ionomer precursor to form compositions useful for making sporting equipment, such as golf ball components. The ionomer or ionomer precursor typically includes plural acid functional groups, such as carboxyl or carboxylate groups, that react or form salts with the amino triazine. Specific examples, without limitation, of suitable amino triazines include guanamine, 6-methyl-1,3,5-triazine-2,4-diamine (acetoguanamine), 6-nonyl-1,3,5-triazine-2,4-diamine (nonylguanamine), 6-phenyl-1,3,5-triazine-2,4-diamine (benzoguanamine) and 2,4,6-triamino-triazine (melamine).

Abstract: The present invention provides a golf ball with excellent abrasion-resistance, durability and resilience having an ionomer resin cover therein. The ionomer composition for the golf ball of the invention comprises a reaction product obtained by reacting a telechelic copolymer having functional groups introduced in both terminals of a binary copolymer formed by copolymerizing an olefin monomer having 2 to 8 carbon atoms and an unsaturated carboxylic acid having 2 to 18 carbon atoms, and/or a ternary copolymer formed by copolymerizing an olefin monomer having 2 to 8 carbon atoms, an unsaturated carboxylic acid having 2 to 18 carbon atoms and an unsaturated carboxylic acid ester with a hydroxyl group-containing compound or an isocyanate group-containing compound, wherein at least 10 mole % of a carboxylic group in said reaction product is neutralized with an inorganic metal.

Abstract: The invention provides golf ball materials which include, in admixture, (A) an oxygen-containing inorganic metal compound, (B) one or more polymers selected from the group consisting of multi-component polyamides, and (C) an acid-containing polymer, and additionally includes, if the oxygen-containing inorganic metal compound (A) does not include a zinc cationic species, (D) a zinc ionomer. The invention also provides methods for preparing such golf ball materials, and golf balls made with the materials. The golf ball materials are multi-component polyamide blend compositions having an excellent flow and processability and a suitable hardness, making them ideal as materials for obtaining high-performance golf balls which are endowed with outstanding durability and scuff resistance without any loss in rebound resilience.

Abstract: A method for manufacturing a golf ball by forming half shell covers using a rubber composition and forming golf ball covers using the half shell covers. The adhesion strength between the bonding surfaces of half shells (durability of golf balls) is improved by keeping the shape of half shells and the thickness of the resulting covers uniform. The adhesion strength between the bonding surfaces of half shells is further increased by using a composition containing a crystalline rubber as the rubber composition for cover; molding the rubber composition at a particular temperature while preserving the shape of the half shells without crosslinking or with only partially crosslinking the rubber component; and forming the half shells into a cover while crosslinking the rubber components.

Abstract: The present invention provides a multi-piece solid golf ball having a core, an inner cover layer and an outer cover layer. The core is made of a material obtained by molding under applied heat a rubber composition containing (a) a base rubber containing polybutadiene having a stress relaxation time (T80) of 3.5 or less, (b) an unsaturated carboxylic acid and/or a metal salt thereof, and (c) an organic peroxide. The inner cover layer has a Shore D hardness of from 50 to 80, the outer cover layer has a Shore D hardness of from 35 to 60 which is lower than the Shore D hardness of the inner cover layer, and the outer cover layer is formed primarily of a specific, highly neutralized resin mixture. The golf ball as a whole has an excellent rebound, a good, soft feel on impact, an outstanding spin performance, and is capable of achieving an increased distance.

Abstract: A golf ball material composed of (A) an oxygen-containing inorganic metal compound in the form of a particulate or a master batch capable of neutralizing at least some of the acid groups in an acid-containing polymer blend, (B) one or more polymer selected from among diene polymers, thermoplastic polymers and thermoset polymers, and (C) an acid-containing polymer is prepared by mixing component A in a blend of components B and C. The golf ball material has a good heat resistance, flowability and processability, and can be used to produce high-performance golf balls having durability, scuff resistance and optimal hardness without a loss of rebound.

Abstract: Golf balls including cores formed from polybutadiene reaction products having a percent change in dynamic stiffness from 0° C. to ?50° C. of less than 130 percent where the reaction products include a resilient polymer component, a crosslinking material, a cis-to-trans catalyst, and a free radical source. The golf balls may be formed with polyurethane covers, covers formed from castable reactive liquid materials, among other materials. The golf balls may also include an intermediate layer.

Abstract: A molded rubber material for golf balls which is obtained by molding and curing a rubber compound composed of base rubber and such ingredients as crosslinking agent, co-crosslinking agent, and vulcanization accelerator, wherein the base rubber is polybutadiene which results from polymerization with the help of a catalyst of rare earth element and has a stress relaxation time (T80) no longer than 5 (measured according to ASTM D 1646-96), the vulcanization accelerator is hexamethylenetetramine, and the rubber compound contains an organosulfur compound. A method for producing the molded rubber material, and a golf ball having the molded rubber material as the solid core. The method permits efficient production of high-quality rubber molded material with high rebound resilience.

Abstract: Golf ball compositions including novel processing aids, e.g., metal salts of unsaturated fatty acids, high styrene resins, transpolyisoprene, and transpolybutadiene, for inclusion in rubber-based compositions that reduce safety risks, mixer down time, increase dispersion of the ingredients during processing, and increase component COR over that of a component formed with a conventional processing aid.

Abstract: A golf ball is composed at least in part of a material molded under heat from a rubber composition which includes: (a) a base rubber composed primarily of a mixture of at least 60 wt % of a polybutadiene having a stress relaxation time (T80), defined as the length of time it takes from the moment when rotor rotation is stopped immediately after measurement of the ML1+4 (100° C.) value (the Mooney viscosity measured at 100° C. in accordance with ASTM D-1646-96) for the ML1+4 value to decrease 80%, of less than 4 seconds with up to 40 wt % of a polybutadiene having a stress relaxation time (T80) of at least 4 seconds; (b) an unsaturated carboxylic acid and/or a metal salt thereof; and (c) an organic peroxide. The golf ball has an excellent manufacturability and rebound.

Abstract: The present invention relates to a golf ball having a ball component made of a material molded under heat from a rubber composition which includes: (A) from 1 to 50 parts by weight of a modified polybutadiene obtained by a modification reaction wherein a polybutadiene having a vinyl content of from 0 to 2%, a cis-1,4 bond content of at least 80% and an active end is modified at the active end with at least one type of alkoxysilane compound, and (B) at least 50 parts by weight of polybutadiene synthesized using a rare-earth catalyst and having a stress relaxation time (T80) of less than 4.0. The rubber composition additionally includes the following per 100 parts by weight of ingredients A and B combined: (C) from 10 to 50 parts by weight of an unsaturated carboxylic acid and/or a metal salt thereof, (D) from 5 to 80 parts by weight of an inorganic filler, and (E) from 0.1 to 10 parts by weight of an organic peroxide.

Abstract: Golf balls including centers formed from polybutadiene reaction products having a percent change in dynamic stiffness from 0° C. to ?50° C. of less than 130 percent where the reaction products include a resilient polymer component, a crosslinking material, a cis-to-trans catalyst, and a free radical source. The golf balls may be formed with polyurethane covers, covers formed from castable reactive liquid materials, among other materials. The golf balls may also include an intermediate layer.

Abstract: Compositions for golf balls including oxirane functional endcapped polymers and, in particular, compositions formed from polyurethane-based or polyurea-based prepolymers that are endcapped with an oxirane functional group. The oxirane functionality is opened with a suitable curing agent to provide a composition that has flexibility via the prepolymer backbone and stiffness via the oxirane functional endcaps.

Abstract: Golf ball 2 has spherical core 4, cover 6 positioned outside the core 4, mark layer 8 and paint layer 10. The resin composition of the cover 6 includes composite particles. The composite particle has a nucleus and a coat layer. The nucleus is constituted with aluminum oxide. The coat layer is constituted with titanium oxide. The composite particles are flaky. The amount of the composite particles is 0.1 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the base resin of the cover 6. The composite particles may be also dispersed in the paint layer 10. The amount of the composite particles in the paint layer 10 is 1 part by weight or more and 30 parts by weight or less per 100 parts by weight of the base resin of the paint layer 10.

Abstract: A golf ball including an inner core layer formed from a thermoset rubber composition and having a first surface hardness; a thermoplastic outer core layer having a second surface hardness, an inner surface hardness, and being formed from a copolymer of ethylene and an ?,?-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to fully-neutralize the acid groups of the copolymer; an inner cover layer; and an outer cover layer; wherein the first surface hardness is less than the second surface hardness by at least 5 Shore C and less than the inner surface hardness by at least 5 Shore C.

Abstract: A golf ball includes an inner core layer formed from a first rubber composition having a first Shore D hardness; an intermediate core layer formed from a second rubber composition; and a thermoplastic outer core layer having a second Shore D hardness. The outer core layer includes a copolymer of ethylene and an ?,?-unsaturated carboxylic acid, an organic acid or salt thereof, and sufficient cation source to fully-neutralize the acid groups of the copolymer. An inner cover layer surrounds the multi-layer core and an outer cover layer is disposed about the inner cover layer. The inner core layer hardness differs from the outer core hardness by at least 10 points.

Abstract: Disclosed herein is novel thermoplastic material and a golf ball utilizing the thermoplastic material. The golf ball (10) preferably comprises a core (12), a cover (16) and optionally a boundary layer (14). At least one of the core (12), cover (16) or boundary layer (14) of the golf ball (10) comprises the thermoplastic material. The thermoplastic material comprises a partially to highly neutralized blend of copolymers additionally comprising a fatty acid or fatty acid salt, and a heavy mass filler in an amount ranging from 10 parts by weight to 50 parts by weight of the material, with the heavy mass filler having a density greater than the copolymer. The golf ball component of the invention has soft feel and resilience that is maintained or improved.

Abstract: A low compression, resilient golf ball having a center including a material formed from the conversion reaction of sufficient amounts of polybutadiene, a free radical source, and a cis-to-trans catalyst to convert a portion of cis-isomer to trans-isomer in the polybutadiene, wherein said material has an amount of trans-isomer greater than the amount of trans-isomer present before the conversion reaction, and wherein the reaction product includes low levels or substantially no antioxidant.

Abstract: A golf ball which is formed from a vulcanized rubber compound composed of 100 parts by weight of a rubber base material, 10 to 60 parts by weight of an unsaturated carboxylic acid and/or a metal salt thereof, 0.1 to 5 parts by weight of an organosulfur compound, 5 to 80 parts by weight of an inorganic filler, and 0.1 to 3 parts by weight of an organic peroxide, the rubber base material being composed of a first polybutadiene accounting for 50 to 95 wt % and a second polybutadiene accounting for 5 to 50 wt %, both polybutadiene being synthesized by using a rare earth element-based catalyst, the first polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML1+4 (100° C.)) no lower than 50 and the second polybutadiene containing no less than 60 wt % of cis-1,4 bonds and having a Mooney viscosity (ML1+, (100° C.)) no higher than 45. The golf ball is characterized by good rebound resilience and good workability with which it is produced.

Abstract: The invention provides a solid golf ball having a solid core and a cover layer that encases the core and has an outermost layer on an outside surface of which are formed a plurality of dimples. The solid core is formed of a rubber composition composed of 100 parts by weight of a base rubber that includes 60 to 100 parts by weight of a polybutadiene rubber having a cis-1,4 bond content of at least 60% and synthesized using a rare-earth catalyst, 0.1 to 5 parts by weight of an organosulfur compound, an unsaturated carboxylic acid or a metal salt thereof, and an inorganic filler. The solid core has a deformation, when compressed under a final load of 130 kgf from an initial load of 10 kgf, of 2.0 to 4.0 mm, and has a specific hardness distribution.

Abstract: A golf ball comprising a layer made from a liquid rubber composition is disclosed. A castable liquid polybutadiene is the preferred principal rubber component. The molecular weight of the castable liquid polybutadiene is at least about 1,000 and the castable liquid polybutadiene is in a liquid state at room temperature. The castable liquid rubber layer can be a cover layer, a casing layer, an intermediate layer or a core layer.

Abstract: The present invention is directed to a golf ball having at least one layer formed from a rubber composition comprising a base rubber, a free radical initiator, and a quinhydrone. The free radical initiator is generally present in the rubber composition in an amount of at least 0.05 parts by weight per 100 parts of the base rubber. The quinhydrone is generally present in the rubber composition in an amount of at least 0.05 parts by weight per 100 parts of the base rubber. The rubber composition may be present in any one or more of a core layer, a cover layer, or an intermediate layer.

Abstract: The present invention is directed to a two-piece golf ball having a core and a cover, wherein the core comprises at least one unsaturated polymer, at least one cross-linking agent, at least one co-cross-linking agent, and at least one peptizer (comprising one or more organic sulfur compounds, or one or more metal or non-metal salts of an organic sulfur compound), and optionally at least one weight adjusting filler. The improved two-piece balls have optimal velocity and distance performance, as well as excellent shot feel, the called “long and soft” combination. The balls also demonstrate excellent durability properties, and ease of manufacture.

Abstract: A low compression, resilient golf ball having a center including a material formed from the conversion reaction of sufficient amounts of polybutadiene, a free radical source, and a cis-to-trans catalyst to convert a portion of cis-isomer to trans-isomer in the polybutadiene, wherein said material has an amount of trans-isomer greater than the amount of trans-isomer present before the conversion reaction, and wherein the reaction product includes low levels or substantially no antioxidant.

Abstract: A method for coating golf ball components is provided and includes the step of adhering a thin layer of a non-ionomeric polyolefin powder to the interior surfaces of a golf ball mold. The polyolefin powder is adhered to the mold using electrostatic, tribostatic or fluidized bed processes. The golf ball component is placed within the mold, and a sufficient amount of heat and pressure is applied to the mold so that the thin layer of non-ionomeric polyolefin powder fuses to the golf ball component.

Abstract: A golf ball including a core and at least one cover layer disposed about the core, wherein the core or the cover layer is formed from a composition comprising a base polymer, a crosslink initiator, and at least one additive comprising phenothiazine or a perhaloalkyl additive having a structure of: where R1 or R5 are —SZ, at least one of R1 to R5 is a perhaloalkyl, perhalocycloalkyl, or perhaloaryl substituent; the remainder of R1 to R5 are the same or different organic substituents or hydrogen; Z is a non-metal cation comprising quaternary ammonium, quaternary pyridinium, quaternary quinolinium, (organo)phosphonium, (organo)sulfonium, (organo)oxonium, (organo)iodonium, or (organo)azonium; and n is an integer of 1 or greater.

Abstract: This invention is directed to golf balls having at least two adjacent layers, wherein a coating layer of metal materials is on at least one surface of the adjacent layers. The adhesion of the adjacent layer is improved by induction heating. The invention also is directed to ink solution for golf equipment comprising metal materials that can improve adhesion of the ink to the golf equipment.

Abstract: An elastomeric composition for forming a golf ball or a component thereof is disclosed that includes the use of a non-conjugated diene monomer having two or more vinyl (CH2?CH—) terminal end groups. The composition produces a molded product exhibiting an enhanced combination of increased compression (i.e., softness) and resilience (C.O.R.).

Abstract: The invention provides a golf ball composed of, at least in part, a molded and crosslinked material obtained from a rubber composition made of a base rubber, a filler, an organic peroxide, an ?,?-unsaturated carboxylic acid and/or metal salt thereof, and a copper salt of a saturated or unsaturated fatty acid. The molded rubber composition has a very high rebound, and is thus useful as a golf ball core for achieving an excellent flight performance.

Abstract: A thermoplastic composition is provided, comprising (a) an acid copolymer, (b) a salt of a high molecular weight, monomeric organic acid; (c) a thermoplastic resin; (d) a cation source; and (e) optionally, a filler. Also provided are one-, two- and three-piece golf balls, and multi-layered golf balls comprising the composition of the invention.

Abstract: A golf ball including a solid core formed from a composition comprising a diene rubber, a metallic fatty acid salt present in an amount of from 6.3 parts to 7.5 parts, a cis-to-trans catalyst present in an amount of 2.35 parts or greater, and an organic peroxide present in an amount of 0.8 parts or less; and a cover; wherein the core has a coefficient of restitution of 0.810 or greater and a compression of 58 to 78.

Abstract: The present invention is directed to a golf ball having at least one layer which includes a polymer composition containing at least 50 wt % of an acid polymer and at least 0.5 wt % of a polyhydric alcohol, wherein the weight percentages are based on the total polymeric weight of the polymer composition. At least 70% of the acid groups of the acid polymer are neutralized by a cation source or a metal salt thereof.

Abstract: A golf ball comprising a core, an outer cover layer, and, optionally, an intermediate layer disposed between the core and the outer cover layer is presently disclosed. At least one layer of the golf ball is formed from a composition free of cystine and comprising at least one additive selected from the group consisting of aliphatic amino acids other than cystine, aromatic amino acids, halogenated amino acids, and amides thereof, peptides thereof, conjugates thereof, esters thereof, salts thereof, and isomers thereof having amine and acid groups. The outer cover layer may comprise a polyurethane or polyurea composition. At least one portion of the golf ball comprises a composition that enhances physical properties and/or performance characteristics (e.g., coefficient of restitution) of the golf ball. Preferably, the coefficient of restitution of the core is 0.8 or greater.

Abstract: A golf ball comprising a core, an outer cover layer, and, optionally, an intermediate layer disposed between the core and the outer cover layer is presently disclosed.

Abstract: The present invention is directed to resilient golf balls and portions thereof including compositions containing zinc dimethacrylate and zinc pentachlorothiophenol, and methods for making same. In particular, the present invention is directed to a golf ball having at least one of a center, cover, or intermediate layer that includes a reaction product that includes a resilient polymer component, a free radical source, zinc dimethacrylate and at least one halogenated organosulfur compound having the following general formula I: where R1-R5 can be substituted or unsubstituted C1-C8 alkyl groups; halogen groups; thiol groups (—SH), carboxylated groups; sulfonated groups; and hydrogen; in any order.

Abstract: A golf ball incorporates nanofiller material in its core, cover, or intermediate layers. Also, a method includes a step of blending into a composition for a golf ball nanocomposite material, nanofiller material or both. The nanocomposite and/or nanofiller materials impart favorable properties to materials used for golf balls, and they provide for greater versatility in usage than materials previously used. Particular compositions incorporating nanocomposite material also are described as suited for use in golf ball compositions.

Abstract: A golf ball comprising a core, an intermediate layer, and a cover. The core, which has a compression of 100 or less and a diameter of between about 1.00 inches and about 1.64 inches, is formed from a first polymer including an acid group fully-neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid; and a nano-material having an average particle size of 100 nm or less, present in an amount sufficient to adjust at least one material property of the first polymer by 5% to 50% when compared to the material property of the first polymer comprising a material identical to the nano-material but having an average particle size greater than 1000 nm. The intermediate layer is formed from a second polymer comprising an acid group fully-neutralized by a salt of an organic acid, a cation source, or a suitable base of the organic acid.

Abstract: Disclosed herein are a novel thermoplastic material and a golf ball utilizing the thermoplastic material. The golf ball (10) preferably comprises a core (12), a cover (16) and optionally a boundary layer (14). At least one of the core (12), cover (16) or boundary layer (14) of the golf ball (10) comprises the thermoplastic material. The thermoplastic material comprises a partially to highly neutralized blend of a copolymer, a metallocene-catalyzed alpha-olefin with a softening comonomer, and a fatty acid or fatty acid salt.

Abstract: A rubber composition for a one-piece golf ball or for a solid core of a solid golf ball having a multilayer construction in which the core is enclosed directly, or with an intermediate layer, by a cover includes (a) 100 parts by weight of a base rubber, (b) 10 to 60 parts by weight of a co-crosslinking agent, (c) 5 to 80 parts by weight of an inorganic filler, (d) 0.1 to 5 parts by weight of an organic peroxide, (e) 0.05 to 5 parts by weight of an organosulfur compound, (f) 0.05 to 5 parts by weight of sulfur, and (g) 1 to 10 parts by weight of a binary copolymer consisting of a polyolefin component and a polyamide component. Golf ball rubber compositions and golf balls made using such compositions have a good resilience and excellent durability.

Abstract: A multi-piece solid golf ball includes a solid core, at least one intermediate layer, and a cover having at least one cover layer. The solid core has a compression deflection of 3.0 mm or more, the intermediate layer is mainly made from a thermoplastic resin and has a Shore D hardness of 45 to 55 and a specific gravity of 1.2 or less, and the cover has a Shore D hardness of 60 or more and a thickness of 1.6 to 2.3 mm. The golf ball further comprises a ratio of the compression deflection of a sphere composed of the solid core covered with the intermediate layer to the compression deflection of the solid core is more than 0.900 and less than 0.970; and a difference in JIS-C hardness between the surface and the center of the solid core is equal to or less than 5.