Golf ball

Abstract

SOLUTION: To provide a golf ball which includes a core and a cover of at least one layer, for coating the core, and in which at least one layer of the cover is formed from a resin composition containing (I)-(III) components of (I) polyurethane or polyurea, (II) thermoplastic polyester elastomer and (III) aromatic vinyl-based elastomer, the (II) component has a Shore D hardness of 45 or less, an impact resilience rate of 74% or less and a melting viscosity of 1.5×104 (dPa s) or less at 200°C / a shear rate of 243 (1 / sec), and the blending amount is 20 pts.mass or less based on 100 pts.mass of the (I) component, and the (III) component has a Shore D hardness of 30 or less, an impact resilience rate of 30% or less, and the blending amount is 20 pts.mass or less based on 100 pts.mass of the (I) component.EFFECT: The golf ball is excellent in controllability at the time of approach shot, and can excellently retain abrasion resistance and moldability.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a golf ball having at least one layer of core and at least one layer of cover.

Background Art

[0002] The required characteristics of a golf ball are mainly an increase in flight distance. In addition, there are performance such as the ball stopping well during approach shots and abrasion resistance. That is, until now, many golf balls that fly well when struck with a driver and have suitable backspin during approach shots have been developed. Recently, many products for professionals and advanced players have adopted urethane resin materials as alternatives to ionomer resin materials.

[0003] Some cover materials of polymer blends based on urethane resin materials and mixed with other resin materials have been proposed. For example, Japanese Patent Application Laid-Open No. 11-9721 (Patent Document 1) proposes using a blend of thermoplastic polyurethane and a styrene-based block copolymer as the main material of the cover in order to improve the abrasion resistance of the cover material. However, this blended cover was insufficient in terms of resilience and abrasion resistance.

[0004] In addition, Japanese Patent Application Laid-Open No. 2021-3451 (Patent Document 2) describes that by using a resin composition in which an aromatic vinyl-based elastomer is blended with a polyurethane resin material as a cover material, a golf ball can be provided that has excellent controllability during approach shots and can maintain good abrasion resistance without reducing the flight distance during driver shots. However, even in the golf ball proposed above, there is also a point that the amount of spin during approach is insufficient, and it is desired to further increase the amount of spin and further enhance the controllability while maintaining good abrasion resistance and moldability.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a golf ball having higher controllability during an approach shot, better scratch resistance and moldability than a conventional golf ball having a urethane cover.

Means for Solving the Problems

[0007] In order to achieve the above object, the present inventor used, as a polymer blend of a resin material mainly composed of polyurethane or polyurea, a specific low-hardness thermoplastic polyester elastomer (component (II) of the present invention) having good compatibility with polyurethane or polyurea, and a specific aromatic vinyl-based elastomer (component (III) of the present invention) having good compatibility with polyurethane or polyurea in a golf ball including a core and a cover. As a result, when a golf ball having a cover made of a molded product of a resin composition composed of these material components was produced, it was found that this golf ball was excellent in controllability during an approach shot and had both good scratch resistance and moldability, leading to the completion of the present invention. That is, the present invention combines the above specific thermoplastic polyester elastomer and specific aromatic vinyl-based elastomer as resins to be added in a resin composition mainly composed of polyurethane or polyurea, resulting in good compatibility with a base resin such as polyurethane, giving the resin composition a low hardness and a rebound resilience of a certain level or more, and enabling the obtainment of a golf ball that satisfies in terms of controllability, scratch resistance and moldability during approach, thus solving the problems of the present invention.

[0008] Accordingly, the present invention provides the following golf ball. 1. In a golf ball comprising at least one layer of a rubber core and at least one layer of a cover covering the core, at least one layer of the cover is made of a resin composition containing the following components (I) to (III): (I) Polyurethane or polyurea (II) Thermoplastic polyester elastomer (III) Aromatic vinyl-based elastomer The thermoplastic polyester elastomer of the component (II) has a Shore D hardness of 45 or less, a coefficient of restitution of 50~67% and a melt viscosity at 200 °C and a shear rate of 243 (1 / sec) of 1.0×10 4 Less than (dPa·s) The amount of the component (II) is 20 parts by mass or less based on 100 parts by mass of the component (I). The aromatic vinyl-based elastomer of the component (III) has a Shore D hardness of 30 or less and a coefficient of restitution of 30% or less, and the amount of the component (III) is 20 parts by mass or less based on 100 parts by mass of the component (I). A golf ball characterized by the above. 2. The golf ball according to the above 1, wherein the amount of the component (II) is 15 parts by mass or less based on 100 parts by mass of the component (I). 3. The golf ball according to the above 1 or 2, wherein the amount of the component (III) is 15 parts by mass or less based on 100 parts by mass of the component (I). 4. The golf ball according to any one of the above 1 to 3, wherein the component (III) is a hydrogenated aromatic vinyl-based elastomer. 5. The golf ball according to any one of the above 1 to 4, wherein the component (III) is an elastomer obtained by hydrogenating a polymer composed of a polymer block mainly composed of an aromatic vinyl compound and a random copolymer block of an aromatic vinyl compound and a conjugated diene compound. 6. The component (III) is a polymer block composed of styrene and a random copolymer block of styrene and butadiene, and is a hydrogenated aromatic vinyl elastomer obtained by hydrogenating a polymer having polymer blocks composed of styrene at both ends and a random copolymer block in the middle. The golf ball according to any one of the above 1 to 5.

Advantages of the Invention

[0009] The golf ball of the present invention has higher controllability during approach shots, can maintain good scratch resistance, and also has good moldability compared to a golf ball having a conventional urethane cover.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in more detail. The golf ball of the present invention is a golf ball in which at least one layer of core is covered with at least one layer of cover, that is, a single-layer or multi-layer cover.

[0011] The above core can be formed using a known rubber material as a base material. As the base rubber, known base rubbers of natural rubber or synthetic rubber can be used. More specifically, it is recommended to mainly use polybutadiene, especially cis-1,4-polybutadiene having at least 40% or more of a cis structure. In addition, in the base rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, etc. can be used in combination with the above-mentioned polybutadiene as desired.

[0012] Also, polybutadiene can be synthesized by metal catalysts such as rare earth element-based catalysts of Nd catalysts, cobalt catalysts, and nickel catalysts.

[0013] The above-mentioned base rubber can be compounded with co-crosslinking agents such as unsaturated carboxylic acids and their metal salts, zinc oxide, inorganic fillers such as barium sulfate and calcium carbonate, organic peroxides such as dicumyl peroxide and 1,1-bis(t-butylperoxy) cyclohexane, etc. Further, if necessary, commercially available anti-aging agents and the like can be appropriately added.

[0014] The above core can be manufactured by vulcanizing and curing a rubber composition containing the above components. For example, knead using a kneader such as a Banbury mixer or a roll, and perform compression molding or injection molding using a mold for the core. Heat the molded body appropriately at a temperature sufficient for the organic peroxide and co-crosslinking agent to act, at 100 to 200 ° C, preferably 140 to 180 ° C, for 10 to 40 minutes, thereby curing the molded body to manufacture it.

[0015] The golf ball of the present invention has a single layer or a plurality of layers of covers covering the core. Examples of such golf ball embodiments include a golf ball having a single layer cover on the core, a golf ball having a core, an intermediate layer covering the core, and an outermost layer covering the intermediate layer.

[0016] In the present invention, as the resin material of at least one layer of the above cover, the following components (I) to (III) (I) Polyurethane or polyurea (II) Thermoplastic polyester elastomer (III) Aromatic vinyl-based elastomer It is formed of a resin composition containing.

[0017] (I) Polyurethane or polyurea

[0018] Polyurethane or polyurea can be the main material or base resin of the above cover material (resin composition). The details of this component, polyurethane (I-a) or polyurea (I-b), are as follows.

[0019] (I-a) Polyurethane

[0020] The structure of the polyurethane consists of a soft segment made of a high molecular polyol (polymeric glycol) which is a long-chain polyol, and a chain extender and a polyisocyanate that constitute the hard segment. Here, as the high molecular polyol used as a raw material, any of those conventionally used in technologies related to polyurethane materials can be used, and there is no particular limitation. For example, polyester polyols, polyether polyols, polycarbonate polyols, polyester polycarbonate polyols, polyolefin polyols, conjugated diene polymerization polyols, castor oil polyols, silicone polyols, vinyl polymerization polyols, etc. can be mentioned. As the polyester polyol, specifically, adipate polyols such as polyethylene adipate glycol, polypropylene adipate glycol, polybutadiene adipate glycol, polyhexamethylene adipate glycol, and lactone polyols such as polycaprolactone polyol can be adopted. Examples of the polyether polyol include poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol), and poly(methyltetramethylene glycol). These may be used alone or in combination of two or more.

[0021] As the above high molecular polyol, it is preferable to use a polyether polyol.

[0022] The number average molecular weight of the above long-chain polyol is preferably in the range of 1,000 to 5,000. By using a long-chain polyol having such a number average molecular weight, a golf ball made of a polyurethane composition excellent in various properties such as the above-mentioned resilience and productivity can be surely obtained. The number average molecular weight of the long-chain polyol is more preferably in the range of 1,500 to 4,000, and still more preferably in the range of 1,700 to 3,500.

[0023] The number average molecular weight mentioned above is the number average molecular weight calculated based on the hydroxyl value measured in accordance with JIS-K1557 (hereinafter the same).

[0024] As the chain extender, those used in the prior art of polyurethane can be preferably used, and there is no particular limitation. In the present invention, a low molecular compound having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule and having a molecular weight of 2,000 or less can be used, and among them, an aliphatic diol having 2 to 12 carbon atoms can be preferably used. Specifically, 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, etc. can be mentioned, and among them, 1,4-butylene glycol can be particularly preferably used.

[0025] As the polyisocyanate, those used in the prior art of polyurethane can be preferably used, and there is no particular limitation. Specifically, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, naphthylene 1,5-diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, dimer acid diisocyanate, one or more selected from the group consisting of can be used. However, depending on the isocyanate species, it may be difficult to control the cross-linking reaction during injection molding.

[0026] In addition, the blending ratio of active hydrogen atoms to isocyanate groups in the polyurethane-forming reaction can be adjusted as appropriate within a preferable range. Specifically, when producing polyurethane by reacting the above-mentioned long-chain polyol, polyisocyanate compound, and chain extender, it is preferable to use each component in a ratio such that the isocyanate groups contained in the polyisocyanate compound are 0.95 to 1.05 moles per 1 mole of active hydrogen atoms possessed by the long-chain polyol and the chain extender.

[0027] The method for producing polyurethane is not particularly limited, and it may be produced by any of the prepolymer method and the one-shot method using a known urethanization reaction with a long-chain polyol, a chain extender, and a polyisocyanate compound. Among them, it is preferable to perform melt polymerization substantially in the absence of a solvent, and particularly preferably to produce by continuous melt polymerization using a multi-screw type extruder.

[0028] As the above-mentioned polyurethane, it is preferable to use a thermoplastic polyurethane material, and particularly preferably an ether-based thermoplastic polyurethane material. As the thermoplastic polyurethane material, commercially available products can be preferably used, and examples thereof include the product name "Pandex" manufactured by DIC Covestro Polymer Co., Ltd. and the product name "Resamin" manufactured by Dainichi Seika Kogyo Co., Ltd.

[0029] (I-b) Polyurea Polyurea is a resin composition mainly composed of urea bonds formed by the reaction of (i) isocyanate and (ii) an amine-terminated compound. This resin composition will be described in detail below.

[0030] (i) Isocyanate As the isocyanate, those used in the conventional technology related to polyurethane can be preferably used, and there is no particular limitation, and those similar to those described for the above polyurethane material can be used.

[0031] (ii) Amine-terminated compound The amine-terminated compound is a compound having an amino group at the end of the molecular chain. In the present invention, the following long-chain polyamines and / or amine-based curing agents can be used.

[0032] The long-chain polyamine is an amine compound having two or more amino groups capable of reacting with an isocyanate group in the molecule and having a number average molecular weight of 1,000 to 5,000. In the present invention, a more preferable number average molecular weight is 1,500 to 4,000, and still more preferably 1,900 to 3,000. Specific examples of the above long-chain polyamines include, but are not limited to, hydrocarbons having amine terminals, polyethers having amine terminals, polyesters having amine terminals, polycarbonates having amine terminals, polycaprolactones having amine terminals, and mixtures thereof. These long-chain polyamines may be used alone or in combination of two or more.

[0033] On the one hand, the amine-based curing agent is an amine compound having two or more amino groups capable of reacting with isocyanate groups in the molecule and having a number average molecular weight of less than 1,000. In the present invention, a more preferable number average molecular weight is less than 800, and still more preferably less than 600.Specific examples of the above amine curing agent include, but are not limited to, ethylenediamine, hexamethylenediamine, 1-methyl-2,6-cyclohexyldiamine, tetrahydroxypropylene ethylenediamine, 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine, 4,4'-bis-(sec-butylamino)-dicyclohexylmethane, 1,4-bis-(sec-butylamino)-cyclohexane, 1,2-bis-(sec-butylamino)-cyclohexane, derivatives of 4,4'-bis-(sec-butylamino)-dicyclohexylmethane, 4,4'-dicyclohexylmethanediamine, 1,4-cyclohexane-bis-(methylamine), 1,3-cyclohexane-bis-(methylamine), diethylene glycol di-(aminopropyl) ether, 2-methylpentamethylenediamine, diaminocyclohexane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, propylenediamine, 1,3-diaminopropane, dimethylaminopropylamine, diethylaminopropylamine, dipropylenetriamine, imide-bis-propylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, isophoronediamine, 4,4'-methylenebis-(2-chloroaniline), 3,5-dimethylthio-2,4-toluenediamine, 3,5-dimethylthio-2,6-toluenediamine, 3,5-diethylthio-2,4-toluenediamine, 3,5-diethylthio-2,6-toluenediamine, 4,4'-bis-(sec-butylamino)-diphenylmethane and its derivatives, 1,4-bis-(sec-butylamino)-benzene, 1,2-bis-(sec-butylamino)-benzene, N,N'-dialkylamino-diphenylmethane, N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 4,4'-methylenebis-(3-chloro-2,6-diethylaniline), 4,4'-methylenebis-(2,6-diethylaniline), m-phenylenediamine, p-phenylenediamine, and mixtures thereof.These amine-based curing agents may be used alone or in combination of two or more thereof.

[0034] (iii) Polyol Although not an essential component, a polyol can be further blended in addition to the above-described components (i) and (ii) in the polyurea. As this polyol, those used in the prior art related to conventional polyurethanes can be preferably used, and there is no particular limitation, but specific examples include the long-chain polyols and / or polyol-based curing agents shown below.

[0035] As the long-chain polyol, any of those conventionally used in the art related to polyurethanes can be used, and there is no particular limitation. For example, polyester polyol, polyether polyol, polycarbonate polyol, polyester polycarbonate polyol, polyolefin-based polyol, conjugated diene polymerization-based polyol, castor oil-based polyol, silicone-based polyol, vinyl polymerization-based polyol, etc. can be mentioned. These long-chain polyols may be used alone or in combination of two or more thereof.

[0036] The number average molecular weight of the above long-chain polyol is preferably 1,000 to 5,000, more preferably 1,700 to 3,500. Within this range of the number average molecular weight, the resilience and productivity, etc. will be even more excellent.

[0037] As the polyol-based curing agent, those used in the conventional technology related to polyurethanes can be preferably used, and there is no particular limitation. In the present invention, a low molecular compound having two or more active hydrogen atoms capable of reacting with isocyanate groups in the molecule and having a molecular weight of less than 1000 can be used. Among them, aliphatic diols having 2 to 12 carbon atoms can be preferably used. Specifically, 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, etc. can be mentioned. Among them, 1,4-butylene glycol can be particularly preferably used. Further, the preferred number average molecular weight of the above polyol-based curing agent is less than 800, more preferably less than 600.

[0038] Regarding the method for producing the above polyurethane, a known method can be adopted, and a known method such as a prepolymer method or a one-shot method can be appropriately selected.

[0039] Regarding the material hardness of the above component (I), from the viewpoints of spin characteristics and scratch resistance obtained as a golf ball, it is preferably 52 or less in Shore D hardness, more preferably 50 or less in Shore D hardness, and even more preferably 48 or less. Further, as the lower limit value, from the viewpoint of moldability, it is preferably 38 or more in Shore D hardness, more preferably 40 or more in Shore D hardness.

[0040] The rebound resilience rate of the above component (I) is preferably 55% or more, more preferably 57% or more, and even more preferably 59% or more from the viewpoint of improving the approach spin amount. The above rebound resilience rate is measured based on the JIS-K 6255:2013 standard.

[0041] The above component (I) is the main material of the resin composition, and from the viewpoint of sufficiently imparting the scratch resistance of the urethane resin, it is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more of the resin composition.

[0042] (II) Thermoplastic polyester elastomer (II) The thermoplastic polyester elastomer of the component imparts a certain degree of resilience to the resin composition, and in combination with this resilience imparting, the spinning amount at the time of approach can be maintained at a certain level or higher. Further, the thermoplastic polyester elastomer of the (II) component has good compatibility with the above-mentioned (I) component which is the base resin, and in particular, has better compatibility than the conventionally used thermoplastic polyester elastomer. As a result, good scratch resistance can be imparted. Furthermore, by blending the above-mentioned thermoplastic polyester elastomer as an essential component in the resin composition, by having a melting viscosity of a certain level or higher, solidifying properties are imparted after molding of the resin composition, that is, the viscosity of the entire resin composition is suppressed from decreasing due to the softness of the above-mentioned (I) component which is the base resin, and it is possible to suppress a decrease in moldability (productivity), an increase in appearance defects of the golf ball after molding, and an increase in production cost due to an increase in cooling time.

[0043] (II) The thermoplastic polyester elastomer of the component is a resin composition comprising (b-1) a polyester block copolymer and (b-2) a hard resin. Further, the above-mentioned (b-1) component is composed of (b-1-1) a high melting point crystalline polymer segment and (b-1-2) a low melting point polymer segment.

[0044] The (b-1-1) high melting point crystalline polymer segment constituting the polyester block copolymer of the above-mentioned (b-1) component is a polyester formed from one or more selected from the group consisting of aromatic dicarboxylic acids or their ester-forming derivatives, diols or their ester-forming derivatives.

[0045] First, specific examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, anthracene dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethane dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sulfoisophthalic acid, and sodium 3-sulfoisophthalate, etc. In the present invention, the aromatic dicarboxylic acid is mainly used, but if necessary, a part of this aromatic dicarboxylic acid may be replaced with an aliphatic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid, and 4,4'-dicyclohexyldicarboxylic acid, or an aliphatic dicarboxylic acid such as adipic acid, succinic acid, oxalic acid, sebacic acid, dodecanedioic acid, and dimer acid. Specific examples of the ester-forming derivative of the dicarboxylic acid include lower alkyl esters, aryl esters, carbonates, and acid halides of the above-mentioned dicarboxylic acids, etc.

[0046] Next, as the diol, a diol having a molecular weight of 400 or less can be preferably used. Specifically, aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, and decamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-dicyclohexanedimethanol, and tricyclodecanedimethanol, and aromatic diols such as xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxy)diphenylpropane, 2,2'-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxyethoxy)phenyl]sulfone, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 4,4'-dihydroxy-p-terphenyl, and 4,4'-dihydroxy-p-quaterphenyl can be exemplified. Specific examples of the ester-forming derivative of the diol include acetyl forms, alkali metal salts, etc. of the above-mentioned diols.

[0047] The above aromatic dicarboxylic acids, diols, and their derivatives may be used alone or in combination of two or more.

[0048] As the component (b-1-1), those composed of polybutylene terephthalate units derived particularly from terephthalic acid and / or dimethyl terephthalate and 1,4-butanediol, those composed of polybutylene terephthalate units derived from isophthalic acid and / or dimethyl isophthalate and 1,4-butanediol, and further, copolymers of both of them can be preferably used.

[0049] The above low melting point polymer segment (b-1-2) is an aliphatic polyether and / or an aliphatic polyester.

[0050] Examples of the aliphatic polyether include poly(ethylene oxide) glycol, poly(propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, a copolymer of ethylene oxide and propylene oxide, an ethylene oxide adduct of poly(propylene oxide) glycol, a copolymer glycol of ethylene oxide and tetrahydrofuran, etc. Examples of the aliphatic polyester include poly(ε-caprolactone), poly(enantholactone), polycaprolactone, polybutylene adipate, polyethylene adipate, etc. In the present invention, from the viewpoint of elastic properties, poly(tetramethylene oxide) glycol, an ethylene oxide adduct of poly(propylene oxide) glycol, a copolymer glycol of ethylene oxide and tetrahydrofuran, poly(ε-caprolactone), polybutylene adipate, and polyethylene adipate, etc. can be preferably used. Further, among these, it is recommended to use poly(tetramethylene oxide) glycol, an ethylene oxide adduct of poly(propylene oxide) glycol, and a copolymer glycol of ethylene oxide and tetrahydrofuran in particular. Also, the number average molecular weight of these segments is preferably about 300 to 6000 in the copolymerized state.

[0051] The component (b-1) can be produced by a known method. Specifically, a method can be adopted in which a lower alcohol diester of a dicarboxylic acid, an excessive amount of a low molecular weight glycol, and a low melting point polymer segment component are subjected to a transesterification reaction in the presence of a catalyst, and the resulting reaction product is polycondensed; or a method in which a dicarboxylic acid, an excessive amount of a glycol, and a low melting point polymer segment component are subjected to an esterification reaction in the presence of a catalyst, and the resulting reaction product is polycondensed, etc.

[0052] In the component (b-1), the proportion of the component (b-1-2) is 30 to 60% by mass. In this case, a preferable lower limit can be 35% by mass or more, and a preferable upper limit can be 55% by mass or less. If the proportion of the component (b-1-2) is too small, there may be insufficient impact resistance and compatibility (especially at low temperatures). On the other hand, if the proportion of the component (b-1-2) is too large, the rigidity of the resin composition (and the molded article) may be insufficient.

[0053] The hard resin of the component (b-2) is not particularly limited. For example, one or more selected from the group consisting of polycarbonate, acrylic resin, styrene resins such as ABS resin and polystyrene, polyester resin, polyamide resin, polyvinyl chloride, and modified polyphenylene ether can be used. In the present invention, a polyester resin can be preferably used from the viewpoint of compatibility, and more preferably, it is recommended to use polybutylene terephthalate and / or polybutylene naphthalate.

[0054] The blending ratio ((b-1):(b-2)) of the above-mentioned components (b-1) and (b-2) is not particularly limited, but is preferably 50:50 to 90:10 by mass ratio, more preferably 55:45 to 80:20. If the proportion of the component (b-1) is too small, there may be insufficient impact resistance (at low temperatures). On the other hand, if the proportion of the component (b-1) is too large, the rigidity and moldability of the composition (and the molded article) may be insufficient.

[0055] As such (II) thermoplastic polyester elastomers, commercially available products can be used. Specific examples include "Hytrel" manufactured by Toray DuPont Co., Ltd.

[0056] Regarding the material hardness of the above (II) component, from the viewpoint of improving the approach spin amount, the Shore D hardness is 45 or less, more preferably 43 or less, and even more preferably 41 or less in terms of Shore D hardness. Also, as the lower limit value, a Shore D hardness of 36 or more is preferable, and more preferably 38 or more in terms of Shore D hardness.

[0057] The rebound resilience rate of the (II) component is preferably 74% or less, more preferably 73% or less, and even more preferably 72% or less from the viewpoint of reducing the initial approach velocity. Also, the lower limit value of the above rebound resilience rate is preferably 50% or more, more preferably 52% or more, and even more preferably 60% or more. The above rebound resilience rate is measured based on the JIS-K 6255:2013 standard.

[0058] (II) The melt viscosity of the thermoplastic polyester elastomer of the component is 1.5×10 4 (dPa·s) or less, preferably 1.45×10 4 (dPa·s) or less, more preferably 1.0× 10 4 (dPa·s) or less, even more preferably 0.8× 10 4 (dPa·s) or less, and the lower limit value is preferably 0.4×10 4 (dPa·s) or more, more preferably 0.5×10 4 (dPa·s) or more. By having this melt viscosity, solidification properties can be imparted after molding of the resin composition, and moldability (productivity) can be maintained well. This melt viscosity indicates the melt viscosity at a shear rate of 243 (1 / sec) when measured with a capillary graph at a temperature condition of 200°C in accordance with ISO 11443:1995.

[0059] (II) With respect to the blending amount of the component, it is 20 parts by mass or less, preferably 15 parts by mass or less, relative to 100 parts by mass of the above (I) component. If this value is exceeded, there is a risk that the scratch resistance will decrease. The lower limit value of the above blending amount is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, relative to 100 parts by mass of the above (I) component.

[0060] (III) Aromatic vinyl-based elastomer Next, (III) the aromatic vinyl-based elastomer will be described. (III) By using the aromatic vinyl-based elastomer in combination with the above-described (II) component, a higher spin amount at the time of approach can be obtained than in conventional golf balls, and the controllability can be sufficiently enhanced. Further, as will be described later, with a small amount of blending below a certain level, the (III) aromatic vinyl-based elastomer has good compatibility with the above (I) component which is the base resin, and also has good compatibility with the thermoplastic polyester elastomer of the above (II) component. In the golf ball and its manufacturing method, the scratch resistance and moldability can be maintained well.

[0061] An aromatic vinyl elastomer is a polymer (elastomer) composed of a polymer block mainly composed of an aromatic vinyl compound and a random copolymer block of an aromatic vinyl compound and a conjugated diene compound. That is, aromatic vinyl elastomers generally have, as represented by SEBS and the like, blocks composed of components of aromatic vinyl compounds as hard segments at both ends and blocks composed of components of conjugated diene compounds as soft segments in the middle. In recent research, polymers in which aromatic vinyl components are randomly incorporated into the middle block in addition to the components of conjugated diene compounds have also been reported. Generally, the hardness of aromatic vinyl elastomers decreases as the aromatic vinyl content serving as the hard segment decreases, and the resilience increases because the soft segment component increases. On the other hand, when aromatic vinyl components are randomly incorporated into the soft component of the middle block, the hardness does not increase much and the resilience decreases. Also, a similar effect can be obtained by using a conjugated diene compound having a high Tg instead of randomly incorporating an aromatic vinyl compound into the middle block. In particular, in the present invention, in order to sufficiently exhibit the above-described operational effects, it is preferable to use, as the component (III), a hydrogenated product of the above polymer (elastomer).

[0062] Examples of the aromatic vinyl compound in the above polymer include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, N,N-diethyl-p-aminoethylstyrene, and the like. These may be used alone or in combination of two or more. Among these groups, styrene is preferable.

[0063] Examples of the conjugated diene compound in the above polymer include butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and the like. These may be used alone or in combination of two or more. Among these groups, butadiene and isoprene are preferable, and butadiene is more preferable.

[0064] In addition, units derived from the above-mentioned conjugated diene compound, for example, units derived from butadiene, become ethylene units or butylene units by undergoing a hydrogenation treatment. For example, when a styrene-butadiene-styrene block copolymer (SBS) is subjected to a hydrogenation treatment, it becomes a styrene-ethylene / butylene-styrene block copolymer (SEBS).

[0065] As described above, as the aromatic vinyl-based elastomer which is the component (III), it is preferable to employ a hydrogenated one, that is, a hydrogenated aromatic vinyl-based elastomer. As the hydrogenated aromatic vinyl-based elastomer, an elastomer obtained by hydrogenating a polymer composed of a polymer block mainly composed of an aromatic vinyl compound and a random copolymer block of an aromatic vinyl compound and a conjugated diene compound is preferable, an elastomer obtained by hydrogenating a polymer composed of a polymer block mainly composed of styrene and a random copolymer block of styrene and butadiene is more preferable, and an elastomer obtained by hydrogenating a polymer composed of a polymer block mainly composed of styrene and a random copolymer block of styrene and butadiene, particularly, having a polymer block mainly composed of styrene at both ends (particularly a polymer block composed only of styrene at both ends) and a random copolymer block in the middle is preferable. By using a copolymer having this structure, both low hardness and low resilience are achieved, and since the solidification rate after molding is fast, there is little tack, and it is considered that the deterioration of physical properties due to blending can be minimized because of excellent compatibility with the main component (I) polyurethane or polyurea.

[0066] Specific examples of the above hydrogenated aromatic vinyl elastomers include, for example, styrene-ethylene·butylene-styrene block copolymer (SEBS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene block copolymer (SIB), styrene-ethylene·propylene-styrene block copolymer (SEPS), styrene-ethylene·ethylene·propylene-styrene block copolymer (SEEPS), styrene-butadiene·butylene-styrene block copolymer (SBBS), styrene-ethylene-propylene block copolymer (SEP), etc.

[0067] In the above aromatic vinyl elastomer, the proportion of the units derived from the aromatic vinyl compound in the copolymer (i.e., the aromatic vinyl compound content, preferably the styrene content) is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, and most preferably 60% by mass or more. Thus, by setting a large content of the aromatic vinyl compound, preferably the styrene content, the compatibility with the polyurethane or polyurea as the component (I) becomes good, and the deterioration of the desired hardness and moldability can be prevented. The measurement of the content of the units derived from the above aromatic vinyl compound (preferably the styrene content) can be calculated by 1 H-NMR measurement.

[0068] In addition, in the above aromatic vinyl elastomer, the glass transition temperature (Tg) indicated by the tanδ peak temperature obtained by dynamic viscoelasticity measurement (DMA) is preferably -20 to 50°C, more preferably 0°C or higher, and still more preferably 5°C or higher. That is, when the tanδ peak temperature is in the vicinity of the temperature at which a golf ball is usually used, it is considered that the resilience of the whole resin composition can be suppressed low in the temperature range where a golf ball is usually used, and the desired effect of the present invention can be enhanced.

[0069] As the aromatic vinyl elastomer which is the component (III), commercially available products can be used. For example, as commercially available products, "S.O.E. (trademark)", "Tuftec", and "Tufprene" manufactured by Asahi Kasei Corporation, or "Dic Styrene" manufactured by DIC Corporation, etc. can be mentioned.

[0070] Regarding the material hardness of the component (III), from the viewpoint of improving the approach spin amount, it is 30 or less in Shore D hardness, more preferably 28 or less in Shore D hardness, and still more preferably 26 or less. Further, as the lower limit value thereof, 18 or more in Shore D hardness is preferable, and more preferably 20 or more in Shore D hardness.

[0071] The rebound resilience rate of the component (III) is preferably 30% or less, more preferably 25% or less, and still more preferably 22% or less, from the viewpoint of maintaining the approach spin amount and suppressing the rebound property during the approach to obtain controllability. By suppressing the rebound resilience rate to be very low in this way, it is possible to realize a decrease in the initial ball speed during the approach shot without adversely affecting the golf ball physical properties with a small addition amount. However, the lower limit value of the rebound resilience rate is preferably 15% or more, and more preferably 20% or more, in order to suppress the influence on the rebound decrease and the reduction of the flight distance during the driver shot as much as possible. The above-mentioned rebound resilience rate is measured based on the JIS-K 6255:2013 standard.

[0072] The blending amount of the component (III) is 30 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, with respect to 100 parts by mass of the component (I). Further, as the lower limit value of the blending amount, it is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, and still more preferably 0.5 part by mass or more. When the blending amount of the component (III) increases, there is a risk that the scratch resistance and moldability deteriorate. On the other hand, when the blending amount of the component (III) is too small, it becomes impossible to obtain a low hardness and a desired rebound elasticity as a cover resin material, and the effect of decreasing the initial ball speed during the approach shot may also decrease.

[0073] In the resin composition containing the above (I) to (III), other resin materials may be blended in addition to the resin components described above. The purpose is from the viewpoints of further improving the fluidity of the resin composition for golf balls, enhancing various physical properties such as resilience and crack durability.

[0074] Specific examples of other resin materials include polyamide elastomers, ionomer resins, ethylene-ethylene·butylene-ethylene block copolymers or modified products thereof, polyacetals, polyethylenes, nylon resins, methacrylic resins, polyvinyl chlorides, polycarbonates, polyphenylene ethers, polyarylates, polysulfones, polyethersulfones, polyetherimides, and polyamideimides. One or more of them can be used.

[0075] Further, the above resin composition can further contain an active isocyanate compound. This active isocyanate compound can react with the main components, polyurethane or polyurea, to further improve the scratch resistance of the entire resin composition. In addition, the fluidity can be improved by the plasticizing effect of isocyanate, thereby improving the moldability.

[0076] As the above isocyanate compound, any isocyanate compound commonly used in ordinary polyurethanes can be used without particular limitation. For example, as aromatic isocyanate compounds, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate or a mixture of both, 4,4-diphenylmethane diisocyanate, m-phenylene diisocyanate, 4,4'-biphenyl diisocyanate, etc. can be mentioned. Hydrogenated products of these aromatic isocyanate compounds, such as dicyclohexylmethane diisocyanate, etc. can also be used. In addition, aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), octamethylene diisocyanate, and alicyclic diisocyanates such as xylylene diisocyanate can be mentioned. Furthermore, blocked isocyanate compounds obtained by reacting the isocyanate groups of a compound having two or more isocyanate groups at the terminal with a compound having active hydrogen, uretdione bodies formed by dimerization of isocyanates, etc. can be mentioned.

[0077] The compounding amount of the above isocyanate compound is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, based on 100 parts by mass of the polyurethane or polyurea resin which is the component (I). Also, as the upper limit value, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. If this compounding amount is too small, a sufficient crosslinking reaction may not be obtained, and improvement in physical properties may not be observed in some cases. On the other hand, if this compounding amount is too large, discoloration due to time, heat or ultraviolet rays may increase, or problems such as loss of thermoplasticity or reduction of resilience may occur in some cases.

[0078] Furthermore, optional additives can be appropriately incorporated into the above resin composition according to the intended use. For example, when using the golf ball material of the present invention as a cover material, various additives such as fillers (inorganic fillers), organic short fibers, reinforcing agents, crosslinking agents, pigments, dispersants, antioxidants, ultraviolet absorbers, and light stabilizers can be added to the above components. When these additives are incorporated, the amount of incorporation is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and preferably 10 parts by mass or less, more preferably 4 parts by mass or less, based on 100 parts by mass of the base resin.

[0079] Regarding the resilience modulus of the above resin composition, in order to improve the approach spin amount, it is required to be 50% or more as measured according to JIS-K 6255:2013 standard, preferably 52% or more, more preferably 54% or more, and the upper limit value is 72% or less, preferably 70% or less, more preferably 68% or less.

[0080] Also, regarding the material hardness of the above resin composition, from the viewpoint of improving the approach spin amount, it is required to be 49 or less in Shore D hardness, preferably 48 or less, more preferably 47 or less in Shore D hardness. As the lower limit value, from the viewpoint of moldability, it is preferably 30 or more in Shore D hardness, more preferably 35 or more in Shore D hardness.

[0081] Regarding the preparation method of each component of the above resin composition, for example, it can be mixed using various kneaders such as a kneading type (single-screw or) twin-screw extruder, Banbury mixer, kneader, and lab plastomill, or each component can be mixed by dry blending during the injection molding of the resin composition. Furthermore, when using the above active isocyanate compound, it may be contained during resin mixing using various kneaders, or a masterbatch containing the active isocyanate compound and other components may be prepared separately in advance, and each component may be mixed by dry blending during the injection molding of the resin composition.

[0082] For example, as a method of molding a cover with the above resin composition, for example, the above resin composition can be supplied to an injection molding machine, and the cover can be molded by injecting the molten resin composition around the core. In this case, the molding temperature varies depending on the type of (I) polyurethane or polyurea, etc., which is the main component, but is usually in the range of 150 to 270°C.

[0083] The thickness of the cover is preferably 0.4 mm or more, more preferably 0.5 mm or more, still more preferably 0.6 mm or more, and as the upper limit, preferably 3.0 mm or less, more preferably 2.0 mm or less.

[0084] When at least one intermediate layer is interposed between the above core and the above, as the material of the intermediate layer, it is preferable to employ various thermoplastic resins used for the cover material of a golf ball, particularly an ionomer resin, and commercially available products can be used as the ionomer resin. In this case, the thickness of the intermediate layer can be set within the same range as the thickness of the above cover.

[0085] In the golf ball of the present invention, from the viewpoint of aerodynamic performance, a large number of dimples are provided on the surface of the outermost layer. There is no particular limitation on the number of dimples formed on the surface of the outermost layer, but from the point of enhancing aerodynamic performance and increasing the flying distance, it is preferably 250 or more, more preferably 270 or more, still more preferably 290 or more, most preferably 300 or more, and as the upper limit value, preferably 400 or less, more preferably 380 or less, still more preferably 360 or less.

[0086] In the present invention, a coating film layer is formed on the cover surface. As the paint for forming this coating film layer, it is preferable to employ a two-component curable urethane paint. Specifically, in this case, the two-component curable urethane paint contains a main agent mainly composed of a polyol resin and a curing agent mainly composed of a polyisocyanate.

[0087] As a method of forming a coating film layer by applying the above paint to the cover surface, there are no particular restrictions, and known methods can be used. Desired methods such as air gun coating method or electrostatic coating method can be used.

[0088] Regarding the thickness of the coating film layer, there are no particular restrictions, but it is usually 8 to 22 μm, preferably 10 to 20 μm.

[0089] In addition, the golf ball of the present invention can conform to the golf rules for competitive use, and the ball outer diameter can be 42.80 mm or less, which does not pass through a ring with an inner diameter of 42.672 mm, and the mass can preferably be formed to be 45.0 to 45.93 g.

Examples

[0090] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples.

[0091] 〔Examples 1 to 12, Comparative Examples 1 to 6〕 Common core By preparing and vulcanizing and molding a rubber composition for the core common to all examples according to the formulation shown in Table 1, a core with a diameter of 38.6 mm was produced.

[0092]

Table 1

[0093] The details of the above core material are as follows. · "cis-1,4-polybutadiene" manufactured by JSR Corporation, trade name "BR01" · "Zinc acrylate" manufactured by Nippon Shokubai Co., Ltd. · "Zinc oxide" manufactured by Sakai Chemical Industry Co., Ltd. · "Barium sulfate" manufactured by Sakai Chemical Industry Co., Ltd. · "Antioxidant" trade name "No Crack NS6" (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) · "Organic peroxide (1)" dicumyl peroxide, trade name "Perk Mill D" (manufactured by NOF Corporation) · "Organic peroxide (2)", a mixture of 1,1-di(tert-butylperoxy)cyclohexane and silica, trade name "Perhexa C-40" (manufactured by NOF Corporation) · "Zinc stearate", manufactured by NOF Corporation

[0094] Common intermediate layer An intermediate layer-coated sphere having an intermediate layer with a thickness of 1.25 mm was produced by injection molding a resin material for the intermediate layer around a core with a diameter of 38.6 mm. The resin material for the intermediate layer had a resin formulation common to all examples, and was a blend of 50 parts by mass of the sodium neutralized product of an ethylene-unsaturated carboxylic acid copolymer with an acid content of 18% by mass and 50 parts by mass of the zinc neutralized product of an ethylene-unsaturated carboxylic acid copolymer with an acid content of 15% by mass, for a total of 100 parts by mass.

[0095] Cover (outermost layer) Next, for Examples 3, 4, 8, 10, 11 and Comparative Examples 1, 2, 3, 5, 6, the outermost cover material shown in Table 2 below was injection molded around the above intermediate layer-coated sphere to produce a three-piece golf ball with a diameter of 42.7 mm having an outermost layer with a thickness of 0.8 mm. At this time, although not particularly shown in the figure, common dimples were formed on the cover surfaces of each example and comparative example. Regarding the resin composition of the cover, it was designed to have the blending amounts of each component shown in Table 2 below, and injection molding was performed at a molding temperature of 200 to 250 °C. Also, for Examples 1, 2, 5 to 7, 9, 12 and Comparative Example 4, in the same manner as above, a three-piece golf ball was produced.

[0096] The details of the components contained in the compositions in Table 2 below are as follows. · "TPU (1)", trade name "Pandex" manufactured by DIC Covestro Polymer GmbH, an ether-type thermoplastic polyurethane (Shore D hardness "43" and rebound elasticity rate "61%") · "TPU (2)", trade name "Pandex" manufactured by DIC Covestro Polymer GmbH, an ether-type thermoplastic polyurethane (Shore D hardness "47" and rebound elasticity rate "54%")

[0097] · "Polyester Elastomer 1", the product name "Hytrel 2401" manufactured by Toray DuPont, a thermoplastic polyether ester elastomer (Shore D hardness "40") · "Polyester Elastomer 2", a mixture of the product name "Hytrel 4001" and the product name "Hytrel 2401" manufactured by Toray DuPont in a mass ratio of 29:1 · "Polyester Elastomer 3", the product name "Hytrel 3001" manufactured by Toray DuPont, a thermoplastic polyether ester elastomer (Shore D hardness "31") · "Polyester Elastomer 4", manufactured by Toray DuPont, a thermoplastic polyether ester elastomer (Shore D hardness "55") · "Polyester Elastomer 5", the product name "Hytrel 4001" manufactured by Toray DuPont, a thermoplastic polyether ester elastomer (Shore D hardness "37") · "Hydrogenated Aromatic Vinyl Elastomer", the product name "S.O.E. S1611" manufactured by Asahi Kasei (styrene content: 60 wt%, Shore D hardness "23", and rebound resilience: 20%), a styrene-ethylene·butylene-styrene block copolymer (SEBS)

[0098] Physical properties of the resin composition 〔1〕Rebound resilience Table 2 shows the rebound resilience of the resin composition measured based on the JIS-K 6255:2013 standard. 〔2〕Melt viscosity Tables 2 and 3 show the melt viscosity at a shear rate of 243 (1 / sec) when measured with a capillary graph at a temperature condition of 200 °C in accordance with ISO 11443:1995.

[0099] The spin performance, initial velocity performance, scratch resistance, controllability, and moldability of each golf ball during approach are evaluated by the following methods. The results are shown in Tables 2 and 3.

[0100] Initial velocity and spin performance during approach Attach a sand wedge (SW) to the golf hitting robot, and measure the initial velocity and backspin amount immediately after hitting at a head speed (HS) of 20 m / s using an initial condition measuring device.

[0101] Controllability In addition, a sensory evaluation of the controllability of the ball during approach was conducted by the following method. The club used was the same sand wedge (SW) product name "Bridgestone Tour Stage TW-03 (loft angle 57°)" as above, and it was evaluated according to the following criteria when a golfer actually hit it. 〔Judgment Evaluation〕 ◎ ··· Extremely excellent in operability. 〇 ··· Excellent in operability. △ ··· Slightly inferior in operability. × ··· Inferior in operability. In addition, in determining whether the operability is excellent, in addition to the level of the spin amount of the ball, the length of the contact time between the ball and the club face due to low resilience also has an impact. When the contact time is long, the operability is good, and when it is short, the operability is poor. Here, the controllability (operability) including the spin amount and the length of the contact time is determined.

[0102] Evaluation of scratch resistance Keep the ball at 23°C, use a swing robot machine, use a pitching wedge (PW) for the club, hit each ball 5 times at a head speed of 33 m / s, and visually evaluate the hitting damage according to the following criteria. ◎ ··· Slightly damaged or hardly noticeable damage. ○ ··· The surface is slightly fluffy or the dimples are slightly chipped. × ··· The dimples are completely scraped off.

[0103] Evaluation of moldability (demolding property) Evaluate each example of the ball for the mold release property from the mold after cover injection molding according to the following criteria. ◎ ··· No injuries such as runner breakage or pin attachment occur during mold release. ○ ··· Scratches such as runner breakage or pin marks occur during demolding, but there is no problem with molding. × ··· Scratches such as runner breakage or pin marks occur during demolding, and molding is not possible.

[0104]

Table 2

[0105]

Table 3

[0106] As shown in the results of Table 2, the golf balls of Comparative Examples 1 to 6 are inferior to the product of the present invention (Examples) in the following points. In Comparative Example 1, the component (II) is not blended in the resin composition, and as a result, the controllability during approach is poor. In Comparative Example 2, the resilience modulus of elasticity of the component (II) in the resin composition is higher than the predetermined range, and as a result, the controllability during approach is poor. In Comparative Example 3, the blending amount of the component (III) in the resin composition is large, and as a result, both the scratch resistance and the moldability are poor. In Comparative Example 4, the melt viscosity of the component (II) in the resin composition is high and the material hardness is high, and as a result, both the scratch resistance and the moldability are poor. In Comparative Example 5, the component (II) is not blended in the resin composition, and as a result, the controllability during approach is poor. In Comparative Example 6, neither the component (II) nor the component (III) is blended, and as a result, the controllability during approach is poor.

Claims

1. In a golf ball comprising at least one layer of a rubber core and at least one layer of a cover covering the core, at least one layer of the cover is made of a resin composition containing the following components (I) to (III): (I) Polyurethane or polyurea (II) Thermoplastic polyester elastomer (III) Aromatic vinyl-based elastomer The thermoplastic polyester elastomer of component (II) has a Shore D hardness of 45 or less, a rebound resilience of 50 to 67%, a melt viscosity at 200 °C and a shear rate of 243 (1 / sec) of 1.0 × 10 4 (dPa·s) or less, and its blending amount is 20 parts by mass or less with respect to 100 parts by mass of component (I). The aromatic vinyl-based elastomer of component (III) has a Shore D hardness of 30 or less, a rebound resilience of 30% or less, and its blending amount is 20 parts by mass or less with respect to 100 parts by mass of component (I). A golf ball characterized by the above.

2. The golf ball according to claim 1, wherein the blending amount of component (II) is 15 parts by mass or less with respect to 100 parts by mass of component (I).

3. The golf ball according to claim 1 or 2, wherein the blending amount of component (III) is 15 parts by mass or less with respect to 100 parts by mass of component (I).

4. The golf ball according to any one of claims 1 to 3, wherein component (III) is a hydrogenated aromatic vinyl-based elastomer.

5. The golf ball according to any one of claims 1 to 4, wherein component (III) is an elastomer obtained by hydrogenating a polymer composed of a polymer block mainly composed of an aromatic vinyl compound and a random copolymer block of an aromatic vinyl compound and a conjugated diene compound.

6. The hydrogenated aromatic vinyl-based elastomer according to any one of claims 1 to 5, wherein the component (III) is a polymer block composed of styrene and a random copolymer block of styrene and butadiene, and is obtained by hydrogenating a polymer having a polymer block composed of styrene at both ends and a random copolymer block in the middle.

Images