Abstract: An object of the present invention is to provide a golf ball having a decreased spin rate on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) a compound represented by the formula (1) as a co-crosslinking agent, and (c) a crosslinking initiator, (R1COO)M(OCOR2)m??(1) in the formula (1), M represents a metal atom, m represents 1 or 2, R1 and R2 are different from each other, represent an alkenyl group having 2 to 30 carbon atoms or an alkynyl group having 2 to 30 carbon atoms and have a carbon-carbon double bond or a carbon-carbon triple bond at an ?-position carbon atom bonding to the carbonyl group, and when m is 2, two of R2 may be identical to or different from each other.

Abstract: In a golf ball having a rubber core and an intermediate layer and outermost layer which encase the core, the intermediate layer is formed of a thermoplastic resin composition which has a flexural rigidity of 400 to 500 MPa and a melt flow rate of 15 g/10 min or less and includes 50 to 100 wt % of a magnesium salt of an ethylenically unsaturated carboxylic acid copolymer, the outermost layer is formed of a polyurethane resin composition having a Shore D material hardness of 55 or less, and the golf ball has a deflection within a given range. Compared with conventional golf balls containing the high-rigidity ionomer resins hitherto used as intermediate layer materials, this ball suppresses the spin rate on shots with a driver and long and middle irons, enabling an increased distance to be obtained, and also has a high durability to repeated impact.

Abstract: In order to satisfy at a high level the golf ball flight and control performances relied on by professional golfers and skilled amateurs, this invention provides a multi-piece solid golf ball G having a core 1, a cover 3 and an intermediate layer 2 therebetween wherein the core is formed of a rubber composition that includes an alcohol having a value obtained by dividing the molecular weight of the alcohol by the number of hydroxyl groups thereon which is 70 or less. Also, letting Hc be the JIS-C hardness at the center of the core, H12 be the JIS-C hardness at a position 12 mm from the core center and Ho be the JIS-C hardness at the surface of the core, the core has a hardness profile in which these hardnesses satisfy fixed relationships defined by specific formulas.

Abstract: An object of the present invention is to provide a golf ball having excellent impact durability. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a core rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinkable compound having two or more polymerizable unsaturated bonds in the molecule, and (d) a crosslinking initiator.

Abstract: A golf ball with improved durability is disclosed herein. The golf ball has a mantle layer comprising a blend of ionomers and methyl methacrylate, butadiene, styrene (MBS) with a weight percentage of MBS ranging from 5 to 15 weight percent of the mantle layer.

Abstract: A golf ball having a center core, one or more envelope layer encasing the center core and one or more cover layer is provided wherein at least one envelope layer is formed of a rubber composition that includes (a) a diene rubber, (b) a tetrazine compound of a specific formula or a metal salt thereof, (c) an ?,?-unsaturated carboxylic acid metal salt and (d) an organic peroxide. A method for manufacturing the golf ball is also provided. The golf ball has a high rebound and durability. The manufacturing method, by eliminating the need to furnish equipment for a bonding step, lowers production costs and is industrially advantageous.

Abstract: An object of the present invention is to provide a golf ball having excellent shot feeling on driver shots. The present invention provides a golf ball comprising a core and at least one cover covering the core, wherein a material for forming the core has a loss tangent difference ? tan ? (tan ??80?tan ??40) of 0.12 or more between a loss tangent tan ??80 at ?80° C. and a loss tangent tan ??40 at ?40° C.

Abstract: Golf ball incorporating polyurethane mixture having wt. % NCO content of ˜4-20 and including a prepolymer polyol portion comprised of trans-?-Farnesene diol(s) in an amount of about 3-70 wt. % of total weight of prepolymer. Trans-?-Farnesene diol may be 15 carbon, long chain, branched, unsaturated 3,4-vinyl-containing bio-hydrocarbon having the formula: Prepolymer can include a 1:99 to 99:1 blend (wt. % ratio) of Trans-?-Farnesene diol(s) and polybutadiene-based polyol(s) in an amount of about 35-85 wt. %, along with about 15 wt. %-65 wt. % of diisocyanate(s). Curative may be combined with prepolymer in amount of about 3-25 wt. % of total weight of curative and prepolymer combined, and may be mixture of aromatic diamine(s) and white dispersion in a wt. % ratio of about 90:10 to 50:50, plus catalyst. Hardness of polyurethane mixture can be from 75. Shore A to 75 Shore D or a material hardness can be from about 40 Shore D to about 65 Shore D.

Abstract: Disclosed herein are heterogeneous golf ball compositions comprising a matrix formed from a thermosetting polymer composition and discrete particles of crosslinked rubber dispersed within the matrix.

Abstract: A golf ball with a core comprising polybutadiene and graphene is disclosed herein. The golf ball has a single core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an inner core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an outer core comprising polybutadiene and graphene.

Abstract: In order to satisfy at a high level the golf ball flight and control performances relied on by professional golfers and skilled amateurs, this invention provides a multi-piece solid golf ball G having a core 1, a cover 3 and an intermediate layer 2 therebetween wherein the core is formed of a rubber composition that includes a lower alcohol having a molecular weight below 200. Also, letting Hc be the JIS-C hardness at the center of the core, H12 be the JIS-C hardness at a position 12 mm from the core center and Ho be the JIS-C hardness at the surface of the core, the core has a hardness profile in which these hardnesses satisfy fixed relationships defined by specific formulas.

Abstract: A golf ball with improved durability is disclosed herein. The golf ball has a mantle layer comprising a blend of ionomers and methyl methacrylate, butadiene, styrene (MBS) with a weight percentage of MBS ranging from 5 to 15 weight percent of the mantle layer.

Abstract: Golf ball incorporating thermoplastic blend of (i) ionomer(s); (ii) different thermoplastic polymer(s) selected from thermoplastic polyurethane(s), thermoplastic urea(s), and/or thermoplastic urea-urethane hybrid(s); and (iii) polyester elastomer(s) and/or polyamide elastomer(s) (“PEPA”). Ionomer is present in amount of about 45 wt % or greater and PEPA present in amount of from about 2 wt % to about 35 wt %. Thermoplastic polymer(s) may be present in amount of from about 8 wt % to about 50 wt %; or from about 25 wt % to about 45 wt %; or from about 35 wt % to about 50 wt %. Ionomer amount may be greater than amount of thermoplastic polymer. Thermoplastic polymer may be a polyurethane present in amount of greater than 20 wt % and to about 40 wt %; while the PEPA is present in amount of from about 5 wt % to about 30 wt %. PEPA is sometimes present in an amount of from about 15 wt % to about 35 wt %.

Abstract: A golf ball with a core comprising polybutadiene and graphene is disclosed herein. The golf ball has a single core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an inner core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an outer core comprising polybutadiene and graphene.

Abstract: The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, wherein the core is formed of a material molded under heat from a rubber composition containing (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate, and has a hysteresis loss of 50% or less when compressed at a load cell speed of 500 mm/min and under a constant load of 5,000 N.

Abstract: A golf ball 2 includes a core 4, a mid layer 6 positioned outside this core, and a cover 8 positioned outside this mid layer. When a total thickness of the mid layer 6 and the cover 8 is denoted by L (mm), a Shore C hardness at a point A away from a surface of the core 4 toward a central point of the core 4 by 5L (mm) is denoted by Ha, a Shore C hardness at a point B away from the surface of the core 4 toward the central point of the core 4 by 2.5L (mm) is denoted by Hb, and a Shore C hardness at the central point of the core 4 and Shore C hardnesses of the mid layer 6 and the cover 8 are denoted by H0, Hm, and Hc, respectively; the golf ball 2 satisfies Hc?Hb>0, Hm?H0>0, and Ha?Hm>0.

Abstract: A rubber composition for golf balls includes (A) a base rubber, (B) two different metal salts of ?,?-unsaturated carboxylic acids having 3 to 8 carbon atoms, (C) a metal salt in which at least one bonding site is a fatty acid of 9 or more carbon atoms, and (D) a crosslinking initiator. Letting component (B) include (B-1) an unsaturated metal carboxylate in a high compounding weight and (B-2) an unsaturated metal carboxylate in a low compounding weight, the ratio (B-2)/(B-1) is from 4 to 20 wt % and the ratio (B-2)/(C) is from 20 to 115 wt %. By using this rubber composition in a golf ball core, the golf ball can be endowed with both good spin properties and good durability on impact.

Abstract: A golf ball 2 includes a core 4, a first mid layer 6, a second mid layer 8, and a cover 12. The core 4 includes a center 18 and an envelope layer 20. The center 18 is formed by crosslinking a first rubber composition, and the envelope layer 20 is formed by crosslinking a second rubber composition. The first rubber composition or the second rubber composition includes a base rubber, a co-crosslinking agent, a crosslinking initiator, and an acid and/or a salt. The co-crosslinking agent is: (1) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms; and/or (2) a metal salt of an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms. A hardness Hm2 of the second mid layer 8 is greater than a hardness Hm1 of the first mid layer 6. The hardness Hm2 is greater than a hardness Hc of the cover 12.

Abstract: A golf ball with a core comprising polybutadiene and graphene is disclosed herein. The golf ball has a single core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an inner core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an outer core comprising polybutadiene and graphene.

Abstract: A golf ball 2 includes a core 4, amid layer 6, a reinforcing layer 8, and a cover 10. The core 4 includes a center 12 and an envelope layer 14. The envelope layer 14 is formed by a rubber composition being crosslinked. The rubber composition includes a base rubber (a), a co-crosslinking agent (b), a crosslinking initiator (c), and an acid and/or a salt (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.

Abstract: An object of the present invention is to provide a golf ball having an excellent initial velocity when being hit at a head speed of 50 m/sec and an improved initial velocity when being hit at a head speed of 40 m/sec. The present invention provides a golf ball comprising a spherical core and a cover covering the spherical core, wherein the golf ball has a rebound equivalence energy ratio (R40) ranging from 65.50% to 99.0% at a deformation amount of 7%, and a rebound equivalence energy ratio (R50) ranging from 20.0% to 70.0% at a deformation amount of 19%, in a compression test (measurement temperature: ?70° C., compression speed: 30 mm/min) applying a load to the golf ball along a radial direction of the golf ball.

Abstract: A method for evaluating the crosslink concentration in a crosslinked rubber is provided. The present invention relates to a method for evaluating the crosslink concentration in a crosslinked rubber by small-angle X-ray scattering or small-angle neutron scattering using measurement samples prepared by swelling the crosslinked rubber to different degrees of swelling.

Abstract: A cold shrink article made from a composition comprising (A) a silicone rubber; (B) an ethylene/?-olefin interpolymer; (C) a filler; and (D) an ?,?-unsaturated carboxylic acid. The composition may optionally include additives selected from the group consisting of plasticizer, peroxide curing agent, antioxidant, process additives, flame retardant and combinations thereof.

Abstract: The present invention relates to golf balls having at least one layer formed from a very neutralized polymer composition. In particular, the compositions of the invention include at least one acid copolymer and a sufficient amount of cation source to neutralize about 70 percent to about 80 percent of the acid moieties. The invention also relates to methods of making the compositions and golf ball constructions that incorporate the compositions of the invention in at least a portion thereof.

Abstract: An object of the present invention is to provide a golf ball having a novel core structure and traveling a great flight distance on driver shots. The present invention provides a golf ball comprising a core composed of a spherical center and an envelope layer and at least one cover layer disposed outside the core, wherein the spherical center has an internal hardness difference between a maximum hardness and a minimum hardness of less than 5 in JIS-C hardness, the envelope layer is formed from an envelope rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) an crosslinking initiator and (d) an acid and/or a salt thereof, and the outermost cover layer has a highest hardness among the constituent members of the golf ball.

Abstract: Disclosed herein are heterogeneous golf ball compositions comprising a matrix formed from a thermosetting polymer composition and discrete particles of crosslinked rubber dispersed within the matrix.

Abstract: In a golf ball having a core and a cover of one or more layers, letting the core diameter be D (mm), the cover thickness be T (mm) and the core and ball deflections when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) be 5 (mm) and B (mm), the following conditions are satisfied: (1) 30?D/T?24, (2) 3.9?E/T?3.0, and (3) 1.18?E/B?1.09. This golf ball provides an excellent flight performance and a soft feel at impact when used by golfers whose head speed is not very fast, such as senior golfers and women golfers. The ball also has a high durability to cracking on repeated impact.

Abstract: Provided is a golf ball comprising a spherical core including an inner layer and an outer layer, an intermediate layer and a cover, wherein a difference (HX+1?HX?1) is 0 or more in Shore C hardness, a surface hardness (HX+Y) of the spherical core is more than 70 in Shore C hardness, an angle ? of a hardness gradient of the inner layer is 0° or more, a difference (???) between the angle ? and an angle ? of a hardness gradient of the outer layer is 0° or more, the intermediate layer has a material hardness (Hm) ranging from 65 to 80 in Shore D hardness, and the intermediate layer has a highest hardness among the constituent members of the golf ball.

Abstract: An object of the present invention is to provide a golf ball showing a great flight distance on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein when JIS-C hardness of the spherical core is measured at points located at distances of 0% (core center), 37.5%, 75.0% and 100% (core surface) from the core center of the spherical core, a hardness difference (Hs?Ho) between a surface hardness (Hs) thereof and a center hardness (Ho) thereof is 20 or more, a ratio ((H37.5?Ho)/(H75.0?Ho)) of a hardness difference (H37.5?Ho) to a hardness difference (H75.0?Ho) is 0.6 or less, and a compression deformation amount (D (mm)) of the spherical core and the 37.5% point hardness (H37.5) satisfy a relation of H37.5??9×D+95.

Abstract: A cured elastomer golf ball component is made by heating an elastomer compound containing an ethylenically unsaturated elastomer, an ethylenically unsaturated monomer, and first and second free radical initiators to a first crosslinking temperature T1 in a compression mold and partially crosslinking the elastomer, then heating to a second crosslinking temperature T2 and curing the elastomer component of the golf ball. Either: (i) the first initiator has a half-life of about 0.2-5 minutes at T1, the second initiator has a half-life of about 0.2-5 minutes at T2, and T2 is higher T1 by at least about 30° C.; or (ii) the second initiator's one-minute half-life temperature is at least about 30° C. higher than the first initiator's one-minute half-life temperature, T1 is within about 20° C. of the first initiator's one-minute half-life temperature, and T2 is within about 20° C. of the second initiator's one-minute half-life temperature.

Abstract: A golf ball 2 includes a core 4, a first mid layer 10, a second mid layer 12, a third mid layer 14, and a cover 8. A volume Vinm and a Shore D hardness Hinm of the first mid layer, a volume Vm and a Shore D hardness Hm of the second mid layer, a volume Voum and a Shore D hardness Houm of the third mid layer, a volume Vc and a Shore D hardness Hc of the cover, and a volume V of an entirety of the ball meet: (a) Hinm<Hm>Houm>Hc, (b) Vinm<Vm>Voum>Vc, (c) Hm?Hc>25, (d) (Vinm+Vm+Voum+Vc)/V<0.40, (e) Vm/Vc>1.50, and (f) (Vm*Hm)/(Vc*Hc)>3.0.

Abstract: Golf ball having a core and a cover of one or more layers, the core being formed of a material molded under heat from a rubber composition including a base rubber, an organic peroxide, and water and/or a metal monocarboxylate. Defining the tan ? slope as (tan ?10?tan ?1)/(10%?1%), where tan ?1 and tan ?10 are the loss tangents at dynamic strains of, respectively, 1% and 10% when the loss tangents of the core center and the core surface are measured at ?12° C. and 15 Hz, the difference between the tan ? slopes at the core surface and the core center is larger than 0.002. Because a core material which undergoes little decrease in resilience over time and experiences little energy loss can be obtained, the golf ball maintains a good rebound, has a reduced spin rate and thus is able to achieve an increased distance.

Abstract: A golf ball comprising an inner core layer including a thermoplastic material and having a geometric center hardness less than the surface hardness to define a positive hardness gradient. An outer core layer is formed over the inner core. The outer core includes a thermoset rubber composition and has an inner surface hardness less than an outer surface hardness to define a positive hardness gradient. A cover layer is formed over the outer core layer. The cover layer includes an inner cover layer and an outer cover layer. The thermoplastic material of the core includes an acid copolymer of ethylene and an ?,?-unsaturated carboxylic acid, optionally a softening monomer comprising alkyl acrylate or methacrylate; a plasticizer; an organic acid or salt thereof; and a cation source present in an amount sufficient to neutralize from about 70 to about 100% of all acid groups present in the material.

Abstract: Golf performance and equipment characteristics may be determined by analyzing the impact between a golf ball and an impacting surface. In some examples, the impacting surface may be a golf club face. The impact between the golf ball and the surface may be measured based on sound and/or motion sensors (e.g., gyroscopes, accelerometers, etc.). Based on motion and/or sound data, various equipment-related information including golf ball compression, club head speed and impact location may be derived. Such information and/or other types of data may be conveyed to a user to help improve performance, aid in selecting golf equipment and/or to insure quality of golfing products.

Abstract: An object of the present invention is to provide a golf ball excellent in shot feeling, flight distance and durability. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a core rubber composition containing (a) a base rubber, (b) a co-crosslinking agent, (c) a crosslinking initiator, and (x) a crosslinked rubber powder; (x) the crosslinked rubber powder contains (x1) soft particles with a hardness difference (Hs?Hp)between a particle hardness (Hp) of the soft particles and a surface hardness (Hs) of the spherical core being 20 or more in JIS-C hardness, and a hardness difference (Hs5?Hp) between the particle hardness (Hp) of the soft particles and a hardness (Hs5) at 5 mm point inside the surface of the spherical core being 15 or more in JIS-C hardness; and the core rubber composition contains (x1) the soft particles in an amount of 1.0 mass % or more.

Abstract: A golf ball has an inner core layer including a thermoplastic highly-neutralized ionomer and having a geometric center hardness less than a surface hardness to define a first positive hardness gradient. An outer core layer is formed about the inner core and includes a homogenous thermoset composition. The outer core has an interior hardness less than an outer surface hardness to define a second positive hardness gradient. An inner and outer cover layers are disposed about outer core layer. The first and second hardness gradients each have a slope and the slope of the second hardness gradient is less than the slope of the first hardness gradient such that a ratio of the first and second slopes is 0.8 to 0.85.

Abstract: An object of the present invention is to provide a golf ball excellent in flying performance, in particular, to provide a golf ball traveling a great flight distance. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) a carboxylic acid, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

Abstract: An object of the present invention is to provide a golf ball comprising a core formed from a rubber composition containing (d) a carboxylic acid and/or a salt thereof and traveling a great flight distance on driver shots. The present invention provides a golf ball comprising a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, (d) a carboxylic acid and/or a salt thereof and two or more kinds of (e) organic sulfur compounds, provided that the rubber composition further contains (f) a metal compound in case of containing only (b) the ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

Abstract: An object of the present invention is to provide a golf ball having a low spin rate on driver shots and excellent in flight distance performance. The present invention provides a golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) a salt of a carboxylic acid, provided that the rubber composition further contains (e) a metal compound in the case of containing only (b) the ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent.

Abstract: A golf ball includes a thermoplastic inner core and a thermoset outer core layer. The inner core has a surface hardness of about 40 to 80 Shore C and a center hardness of about 30 to 75 Shore C, the center hardness being less than the surface hardness to define a first positive hardness gradient. The cover includes an inner cover layer and an outer cover layer. The thermoplastic inner core comprises a highly-neutralized ionomer including an acid copolymer of ethylene and an ?,?-unsaturated carboxylic acid; a plasticizer; an organic acid or salt thereof; and a cation source present in an amount sufficient to neutralize from about 70 to 100% of the acid groups present. The outer core layer includes a polybutadiene rubber and has a surface hardness greater than an interior hardness to define a positive hardness gradient of less than about 25 Shore C.

Abstract: A golf ball has a core, core center, or core layer containing a thermoset elastomer and a polyurethane prepared by combining a thermosetting elastomer and an isocyanate-functional polyurethane, which may be an elastomeric polyurethane, then curing the thermosetting elastomer.

Abstract: An injection molded product formed from an inner layer, or substrate, to which an aesthetic IMD layer is bonded during a first injection molding process, leaving a portion of the substrate exposed about the perimeter(s) of the substrate. A transparent outer layer, or overmold, is then injection molded over the top of the IMD layer and substrate, bonding substantially to the IMD layer and to the substrate where it remains exposed following the first injection molding. The process of forming a product through the disclosed two-step injection molding process creates a customizable, aesthetic product with an aesthetic IMD layer completely encapsulated between the substrate and a clear overmold in such a way to protect the IMD layer from the environment in which the product is used.

Abstract: The present invention provides a resin composition for golf balls that is excellent in resilience, flexibility, and fluidity. The present invention also provides a golf ball excellent in resilience, shot feeling, and productivity. The present invention includes a resin composition for golf balls including: (A) at least one selected from the group consisting of (a-1) a bipolymer of an olefin and a C3-C8 ?,?-unsaturated carboxylic acid, (a-2) a metal ion-neutralized product of a bipolymer of an olefin and a C3-C8 ?,?-unsaturated carboxylic acid, (a-3) a terpolymer of an olefin, a C3-C8 ?,?-unsaturated carboxylic acid, and an ?,?-unsaturated carboxylic acid ester, and (a-4) a metal ion-neutralized product of a terpolymer of an olefin, a C3-C8 ?,?-unsaturated carboxylic acid, and an ?,?-unsaturated carboxylic acid ester; (B) a compound containing an unsaturated hydrocarbon chain, a cationic moiety, and an anionic moiety in its molecule; and (C) an unsaturated fatty acid.

Abstract: The invention provides a golf ball having a core and a cover of at least one layer. The core has a cross-sectional hardness which, letting (H?14) be a JIS-C hardness at a position 14 mm in from a surface toward a center of the core, (H?8) be a JIS-C hardness at a position 8 mm in from the surface toward the center of the core, (H?6) be a JIS-C hardness at a position 6 mm in from the surface toward the center of the core, and (H?4) be a JIS-C hardness at a position 4 mm in from the surface toward the center of the core, satisfies the formulas (1) H?14<70, (2) H?8<72, (3) H?6<75, and (3) H?4?H?8>8.

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: An object of the present invention is to provide a golf ball polyurethane composition excellent in resilience. Another object of the present invention is to provide a golf ball excellent in a shot feeling and resilience. The present invention provides a golf ball polyurethane composition comprising, as a resin component, a polyurethane elastomer including a polyisocyanate with at least two alicyclic hydrocarbon structures having 3 or more carbon atoms as a constituting component, and having a spin-lattice relaxation time (T1) of 13C nucleus of 7.3 seconds or less measured by a High resolution solid state nuclear magnetic resonance (NMR) method.

Abstract: An object of the present invention is to provide a golf ball polyurethane composition excellent in resilience. Another object of the present invention is to provide a golf ball excellent in a shot feeling and resilience. The present invention provides a golf ball polyurethane composition comprising, as a resin component, a polyurethane elastomer including a polyisocyanate with at least two alicyclic hydrocarbon structures having 3 or more carbon atoms as a constituting component, and having a storage modulus E? (Pa) and a loss modulus E? (Pa) satisfying a following expression; log(E?/E?2)??6.08 when measured in a tensile mode using a dynamic viscoelasticity measuring apparatus.

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: Multi-piece golf balls having a solid core and cover are provided. The ball contains a small, heavy inner core and surrounding outer core layer. The inner core preferably contains metal materials such as copper, steel, brass, tungsten, titanium, nickel, iron, tin, and bronze particles. The outer surface of the inner core preferably has a non-uniform structure and includes projecting members. For example, the outer surface may contain multiple projecting ribs with gaps located between the ribs. The ball includes a cover surrounding the core structure. The cover may be multi-layered.

Abstract: A golf ball 2 includes a core 4, a mid layer 6 positioned outside the core 4, a reinforcing layer 8 positioned outside the mid layer 6, and a cover 10 positioned outside the reinforcing layer 8. The core 4 is obtained by a rubber composition being crosslinked. The rubber composition includes a base rubber, a co-crosslinking agent, a crosslinking initiator, and a carboxylate. The co-crosslinking agent is: (1) an ?, ?-unsaturated carboxylic acid having 3 to 8 carbon atoms; and/or (2) a metal salt of an ?, ?-unsaturated carboxylic acid having 3 to 8 carbon atoms. The amount of the carboxylate is equal to or greater than 1.0 parts by weight but less than 40 parts by weight per 100 parts by weight of the base rubber. A hardness of the mid layer 6 is greater than a hardness of the cover 10.