Golf ball material, golf ball, and composition

Abstract

This golf ball material comprises (A) an ionomer in which 20-90% of carboxy groups of an ethylene-unsaturated carboxylic acid-based copolymer are neutralized by metal ions, and (B) a liquid elastomer, wherein the content of the ionomer (A) is 70-99 parts by mass relative to 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B); and the content of the liquid elastomer (B) is 1-30 parts by mass relative to 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B).

Description

Golf ball materials, golf balls, and compositions

[0001] The present disclosure relates to golf ball materials, golf balls, and compositions.

[0002] Ionomer resins have traditionally been used as golf ball materials because of their excellent properties in terms of durability, impact resilience, and the like.

[0003] Generally, the harder the ionomer resin, the better its resilience. For this reason, hard ionomer resins are used to improve the distance a golf ball can travel.

[0004] Patent Document 1 discloses a golf ball cover composition comprising (A) a rubber-like elastomer composition containing (a) an ionomer resin, (b) a thermoplastic urethane-based material, and (c) a rubber-like elastomer as essential components, and characterized in that the molded product has a Shore D hardness of 45 to 63, and a golf ball having a cover formed from said composition.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-331048

[0006] In recent years, golf balls have been designed to have a lower hardness in the surface layer in order to improve the feel and ball controllability when hitting the ball.

[0007] However, when the hardness of a golf ball is reduced, the bending rigidity and impact resilience generally tend to be lost.

[0008] An object of one embodiment of the present disclosure is to provide a golf ball material, a golf ball, and a composition that have excellent flexural rigidity despite a low hardness.

[0009] Means for solving the above problems include the following aspects.<1> A golf ball material comprising: (A) an ionomer obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions; and (B), wherein the content of the ionomer (A) is 70 to 99 parts by weight per 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by weight per 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B).<2> The golf ball material according to <1>, wherein the Shore D hardness measured in accordance with JIS K 7215 is 46.0 or less. <3> The golf ball material according to <1> or <2>, wherein the liquid elastomer (B) has a viscosity of 0.1 Pa·s to 10,000 Pa·s at 38°C. <4> The golf ball material according to any one of <1> to <3>, wherein the ethylene-unsaturated carboxylic acid copolymer is an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer. <5> The golf ball material according to any one of <1> to <4>, wherein the ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer is an ethylene-α,β-unsaturated carboxylic acid-isobutyl acrylate copolymer. <6> The golf ball material according to any one of <1> to <5>, wherein at least some of the metal ions in the ionomer (A) are monovalent metal ions. <7> The golf ball material according to any one of <1> to <5>, wherein at least some of the metal ions in the ionomer (A) are divalent metal ions. <8> The golf ball material according to any one of <1> to <7>, wherein the liquid elastomer (B) is at least one selected from the group consisting of a diene-based elastomer, a silicone-based elastomer, a urethane-based elastomer, and an ethylene-α-olefin oligomer. <9> The golf ball material according to any one of <1> to <8>, wherein the flexural rigidity measured in accordance with JIS K 7106 is 20.0 MPa or greater. <10> A golf ball comprising the golf ball material according to any one of <1> to <9> in at least one of the skin layer, mid layer, and core layer.<11> A composition comprising an ionomer (A) obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions, and a liquid elastomer (B), wherein the content of the ionomer (A) is 70 to 99 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B). <12> The composition according to <11>, wherein the ethylene-unsaturated carboxylic acid copolymer is an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer. <13> The composition according to <11> or <12>, wherein the viscosity of the liquid elastomer (B) at 38°C is 0.1 Pa s to 10,000 Pa s.

[0010] According to one embodiment of the present disclosure, a golf ball material, a golf ball, and a composition are provided that have low hardness but excellent flexural rigidity.

[0011] The golf ball materials, golf balls, and compositions of the present disclosure are described below.

[0012] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In this disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In this disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in a composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.

[0013] In the present disclosure, the term "(meth)acrylic" means acrylic or methacrylic.

[0014] In this disclosure, "liquid" means liquid at 25°C.

[0015] <Golf Ball Material> The golf ball material of the present disclosure is a golf ball material comprising an ionomer (A) formed by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions, and a liquid elastomer (B), wherein the content of the ionomer (A) is 70 to 99 parts by weight per 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by weight per 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B). Due to the above-described composition, the golf ball material of the present disclosure has excellent flexural rigidity despite its low hardness.

[0016] Each of these will be explained in detail below.

[0017] Ionomer (A) Obtained by Neutralizing 20% ​​to 90% of the Carboxyl Groups of an Ethylene-Unsaturated Carboxylic Acid Copolymer with Metal Ions The golf ball material of the present disclosure includes at least one ionomer (A) (hereinafter simply referred to as "ionomer (A)") obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions.

[0018] The ethylene-unsaturated carboxylic acid copolymer in the ionomer (A) is a copolymer in which at least ethylene and an unsaturated carboxylic acid are copolymerized. The copolymer may be a binary copolymer in which ethylene and an unsaturated carboxylic acid are copolymerized, or a terpolymer in which a third monomer is copolymerized in addition to ethylene and an unsaturated carboxylic acid. From the viewpoint of obtaining a golf ball material that has low hardness but excellent flexural rigidity, a terpolymer in which ethylene, an unsaturated carboxylic acid, and a third structural unit are copolymerized is preferred.

[0019] The ethylene-unsaturated carboxylic acid copolymer in the ionomer (A) may be any of a block copolymer, a random copolymer, and a graft copolymer. From the viewpoint of availability, a binary random copolymer, a ternary random copolymer, a graft copolymer of a binary random copolymer, or a graft copolymer of a ternary random copolymer is preferred, and among these, a binary random copolymer or a ternary random copolymer is more preferred from the viewpoint of economic efficiency.

[0020] When the ionomer (A) is a terpolymer, examples of the third monomer other than ethylene and unsaturated carboxylic acid in the ionomer (A) include unsaturated carboxylic acid esters, unsaturated hydrocarbons (e.g., propylene, butene, 1,3-butadiene, pentene, 1,3-pentadiene, 1-hexene, etc.), vinyl esters (e.g., vinyl acetate, vinyl propionate, etc.), vinyl sulfate, vinyl nitrate, vinyl halides (e.g., vinyl chloride, vinyl fluoride, etc.), vinyl group-containing primary amine compounds, and vinyl group-containing secondary amine compounds. Of these structural units, unsaturated carboxylic acid esters are preferred from the viewpoint of obtaining a golf ball material that has excellent flexural rigidity despite a low hardness.

[0021] Examples of unsaturated carboxylic acids that form the structural units of the ethylene-unsaturated carboxylic acid copolymer in the ionomer (A) include α,β-unsaturated carboxylic acids, β,γ-unsaturated carboxylic acids, and γ,δ-unsaturated carboxylic acids. Of these, α,β-unsaturated carboxylic acids are preferred from the viewpoint of obtaining a golf ball material that has low hardness but excellent flexural rigidity. Examples of α,β-unsaturated carboxylic acids include α,β-unsaturated carboxylic acids having 4 to 8 carbon atoms, such as (meth)acrylic acid, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, maleic acid, and maleic anhydride, as well as acid anhydrides thereof. Of these, (meth)acrylic acid is preferred as the unsaturated carboxylic acid from the viewpoint of easy availability.

[0022] Examples of the unsaturated carboxylic acid ester, which is the third monomer forming the terpolymer, which is a preferred embodiment of the ethylene-unsaturated carboxylic acid copolymer in the ionomer (A), include unsaturated carboxylic acid alkyl esters. The alkyl moiety of the alkyl ester in the unsaturated carboxylic acid alkyl ester preferably has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. Examples of the alkyl moiety include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-ethylhexyl, and isooctyl.

[0023] Specific examples of unsaturated carboxylic acid alkyl esters include methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate; methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, isooctyl methacrylate; dimethyl maleate, and diethyl maleate.

[0024] Preferable specific examples of the ethylene-unsaturated carboxylic acid copolymer in the ionomer (A) include, as a binary copolymer, an ethylene-(meth)acrylic acid copolymer, and as a terpolymer, an ethylene-(meth)acrylic acid-(meth)acrylic acid ester copolymer (for example, an ethylene-(meth)acrylic acid-methyl (meth)acrylate copolymer, an ethylene-(meth)acrylic acid-ethyl (meth)acrylate copolymer, an ethylene-(meth)acrylic acid-isobutyl (meth)acrylate copolymer, an ethylene-(meth)acrylic acid-n-butyl (meth)acrylate copolymer, etc.). As long as the effects of the present disclosure are obtained, one type of ionomer (A) may be used alone, or two or more types may be used in combination.

[0025] The content of unsaturated carboxylic acid-derived structural units in the ethylene-unsaturated carboxylic acid copolymer in the ionomer (A) is preferably 5% to 25% by weight, more preferably 10% to 25% by weight, and even more preferably 15% to 25% by weight, based on 100% by weight of the copolymer. Having the content of unsaturated carboxylic acid-derived structural units in this range makes it easier to obtain a golf ball material that has excellent flexural rigidity despite having a low hardness.

[0026] When the ethylene-unsaturated carboxylic acid copolymer is an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester terpolymer, the content of the unsaturated carboxylic acid ester-derived structural units in the terpolymer is preferably 3% to 25% by mass, and more preferably 5% to 20% by mass, relative to 100% by mass of the copolymer, from the viewpoint of ensuring flexibility. A content of the unsaturated carboxylic acid ester-derived structural units of 3% by mass or more is advantageous in terms of ensuring flexibility, and a content of 25% by mass or less is advantageous in terms of preventing blocking.

[0027] The ionomer (A) according to the golf ball material of the present disclosure is a compound in which carboxyl groups contained in an ethylene-unsaturated carboxylic acid copolymer have been neutralized with metal ions. At least some of the metal ions in the ionomer (A) may be monovalent metal ions, such as lithium ions, sodium ions, and potassium ions. At least some of the metal ions in the ionomer (A) may be divalent metal ions, such as rubidium ions, cesium ions, zinc ions, magnesium ions, and manganese ions. The ionomer (A) may contain both an ionomer neutralized with a monovalent metal ion and an ionomer neutralized with a divalent metal ion. From the viewpoint of availability, ionomers neutralized with metal ions selected from zinc ions, magnesium ions, and sodium ions are preferred. From the viewpoint of obtaining a golf ball material that has low hardness but excellent flexural rigidity, ionomers neutralized with zinc ions are more preferred.

[0028] In the golf ball material of the present disclosure, the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer constituting the ionomer (A) are neutralized with metal ions by 20% to 90%. A degree of neutralization of 20% or more tends to provide a better thickening effect. A degree of neutralization of 90% or less tends to provide excellent processability and moldability. The degree of neutralization is more preferably 15% to 82%, and even more preferably 30% to 75%. The degree of neutralization is the ratio (%) of the number of moles of carboxyl groups neutralized with metal ions to the number of moles of carboxyl groups in the ethylene-unsaturated carboxylic acid copolymer.

[0029] In the golf ball material of the present disclosure, the content of the ionomer (A) is 70 to 99 parts by weight, preferably 72 to 97 parts by weight, more preferably 73 to 96 parts by weight, even more preferably 74 to 95 parts by weight, particularly preferably 75 to 94 parts by weight, and most preferably 76 to 93 parts by weight, based on 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B). When the content of the ionomer (A) is 70 to 99 parts by weight based on 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B), a golf ball material with low hardness but excellent flexural rigidity is obtained. When the content of the ionomer (A) is less than 70 parts by weight based on 100 parts by weight of the combined content of the ionomer (A) and the liquid elastomer (B), the flexural rigidity is low despite the low hardness, and a golf ball material with low hardness but excellent flexural rigidity is not obtained. On the other hand, if the content of the ionomer (A) exceeds 99 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B), the flexural rigidity will be excellent but the hardness will not be low, and a golf ball material having low hardness and excellent flexural rigidity will not be obtained.

[0030] Liquid Elastomer (B) The golf ball material of the present disclosure contains a liquid elastomer (B). By including a predetermined amount of liquid elastomer (B), a golf ball material can be obtained that has excellent flexural rigidity despite having a low hardness.

[0031] Examples of the liquid elastomer (B) include diene-based elastomers, silicone-based elastomers, urethane-based elastomers, and ethylene-α-olefin oligomers.

[0032] Examples of the structural units of the diene elastomer include structural units derived from a monomer selected from butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethylbutadiene, 2-phenylbutadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and chloroprene. The diene elastomer preferably comprises a structural unit derived from a monomer selected from butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene, and more preferably comprises a structural unit derived from butadiene or isoprene (2-methyl-1,3-butadiene).

[0033] Examples of the structural units of silicone elastomers include structural units derived from silanol group-containing polysiloxanes.

[0034] Examples of the structural units of the urethane elastomer include structural units derived from monomers selected from polyisocyanates and polymer polyols. Examples of the polyisocyanate include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), and hexamethylene diisocyanate (HDI). Examples of the polymer polyol include polyester polyol, polyether polyol, caprolactone ester polyol, polycarbonate ester polyol, and silicone polyol.

[0035] Examples of ethylene-α-olefin oligomers include oligomers of ethylene and α-olefins having 3 to 8 carbon atoms. An oligomer refers to a low-molecular-weight copolymer having a molecular weight of 1,000 or less. Examples of α-olefins having 3 to 8 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 3,3-dimethyl-1-butene, 1-heptene, 5-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2,3,3-trimethyl-1-butene, 2-ethyl-1-pentene, 1-octene, 2-methyl-1-pentene, 2,3-dimethyl-1-hexene, 2,3,3-trimethyl-1-pentene, 3-ethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, and 2,3-dimethyl-1-butene. These α-olefins may be used alone or in combination of two or more.

[0036] Among the above examples, diene-based elastomers are preferred from the viewpoint of imparting the excellent mechanical properties, particularly flexibility and strength, derived from the liquid elastomer (B) to the golf ball material and contributing to the production of a golf ball material that has excellent flexural rigidity despite its low hardness. The constituent units derived from the diene-based elastomer may be of one type alone, or may contain two or more types, as long as the object of the present disclosure can be achieved.

[0037] The liquid elastomer (B) may further contain other structural units in addition to those exemplified above. Examples of other structural units include structural units derived from aromatic vinyl compounds. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, and divinylbenzene.

[0038] The liquid elastomer (B) may also be modified with various functional groups, such as amino, amide, imino, imidazole, urea, alkoxysilyl, hydroxyl, epoxy, ether, carboxyl, carbonyl, mercapto, isocyanate, nitrile, acid anhydride (e.g., maleic anhydride), and ester (e.g., maleic ester). Modification can result in a golf ball material that is suitable for producing golf balls with low hardness but excellent flexural rigidity.

[0039] From the perspective of obtaining a golf ball material that has low hardness but excellent flexural rigidity, the viscosity of liquid elastomer (B) at 38°C is preferably 0.1 Pa·s to 10,000 Pa·s, more preferably 1 Pa·s to 1,000 Pa·s, and even more preferably 10 Pa·s to 500 Pa·s. When the viscosity of liquid elastomer (B) at 38°C is 1 Pa·s to 1,000 Pa·s, the golf ball material is likely to have excellent flexural rigidity despite its low hardness. The viscosity of liquid elastomer (B) at 38°C can be measured using a Brookfield viscometer.

[0040] In the golf ball material of the present disclosure, the content of liquid elastomer (B) is 1 to 30 parts by weight, preferably 3 to 27 parts by weight, more preferably 4 to 27 parts by weight, even more preferably 5 to 25 parts by weight, particularly preferably 6 to 25 parts by weight, and most preferably 8 to 20 parts by weight, per 100 parts by weight of the combined content of ionomer (A) and liquid elastomer (B). By having the content of liquid elastomer (B) be 1 to 30 parts by weight, per 100 parts by weight of the combined content of ionomer (A) and liquid elastomer (B), a golf ball material that has excellent flexural rigidity despite its low hardness can be obtained. If the content of liquid elastomer (B) is less than 1 part by mass per 100 parts by mass of the combined content of ionomer (A) and liquid elastomer (B), the resulting golf ball material will have low hardness and low flexural rigidity, or will have excellent flexural rigidity but not low hardness, and will not have low hardness but excellent flexural rigidity. On the other hand, if the content of liquid elastomer (B) is more than 30 parts by mass per 100 parts by mass of the combined content of ionomer (A) and liquid elastomer (B), the resulting golf ball material will have low hardness and low flexural rigidity, and will not have low hardness but excellent flexural rigidity.

[0041] In the golf ball material of the present disclosure, the combined amount of the ionomer (A) and the liquid elastomer (B) per 100 parts by weight of the golf ball material is, for example, preferably at least 60 parts by weight, more preferably at least 70 parts by weight, even more preferably at least 80 parts by weight, and particularly preferably at least 90 parts by weight.

[0042] The golf ball material of the present disclosure may contain various additives other than the ionomer (A) and the liquid elastomer (B), such as other thermoplastic resins, tackifying resins, waxes, antioxidants, weather stabilizers, light stabilizers, heat stabilizers, UV absorbers, lubricants, pigments, dyes, and inorganic fillers.

[0043] <Method of Manufacturing Golf Ball Material> There are no particular limitations on the method of manufacturing the golf ball material of the present disclosure. The golf ball material of the present disclosure can be manufactured, for example, by feeding the aforementioned ionomer (A) and liquid elastomer (B) to a feeder of a melt kneader in a specific ratio and melt-kneading them. Melt-kneading can be carried out using a kneader such as a single-screw extruder, twin-screw extruder, kneader, or Banbury mixer. The golf ball material of the present disclosure may also be manufactured, for example, by blending the aforementioned ionomer (A), liquid elastomer (B), and the various additives and melt-kneading them.

[0044] <Physical Properties of Golf Ball Material> —MFR— From the viewpoints of flowability and moldability, the melt flow rate (MFR) of the golf ball material of the present disclosure, measured at a temperature of 190°C under a load of 2,160 g, is preferably 0.1 g / 10 min to 100 g / 10 min, more preferably 0.5 g / 10 min to 50 g / 10 min, and even more preferably 1.0 g / 10 min to 10 g / 10 min. The melt flow rate (MFR) is a value measured in accordance with JIS K 7210-1:2014.

[0045] -Shore D Hardness- From the viewpoint of excellent flexural rigidity even at a low hardness, the Shore D hardness of the golf ball material of the present disclosure is preferably 46.0 or less, more preferably less than 45.5, even more preferably less than 45, particularly preferably less than 44.5, and most preferably less than 44.0. The lower the Shore D hardness, the better, with the lower limit preferably being 30 or greater. The Shore D hardness is a value measured in accordance with JIS K 7215.

[0046] - Flexural Rigidity - From the viewpoint of exhibiting high flexural rigidity even with low hardness, the flexural rigidity of the golf ball material of the present disclosure is preferably 20.0 MPa or greater, more preferably 20.5 MPa or greater, even more preferably 21.0 MPa or greater, particularly preferably 21.5 MPa or greater, and particularly preferably 22.0 MPa or greater. The higher the flexural rigidity, the better, and the upper limit may be 40 MPa or less. The flexural rigidity is a value measured in accordance with JIS K 7106.

[0047] <Uses of Golf Ball Material> As described above, the golf ball material of the present disclosure exhibits excellent flexural rigidity despite its low hardness, and therefore, it is preferable for the golf ball to contain the golf ball material of the present disclosure in at least one of the skin layer, intermediate layer, and core layer. By including the golf ball material of the present disclosure in at least one of the skin layer, intermediate layer, and core layer of a golf ball, it is possible to obtain a golf ball that exhibits excellent flexural rigidity despite its low hardness. In order to achieve excellent golf ball distance, i.e., excellent rebound resilience, and excellent ball controllability, it is preferable for the golf ball material of the present disclosure to be contained in at least one of the skin layer and intermediate layer of the golf ball, and it is particularly preferable for it to be contained in at least the skin layer.

[0048] <Composition> The composition of the present disclosure comprises an ionomer (A) obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions, and a liquid elastomer (B), wherein the content of the ionomer (A) is 70 to 99 parts by mass per 100 parts by mass of the combined content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by mass per 100 parts by mass of the combined content of the ionomer (A) and the liquid elastomer (B). As with the golf ball material described above, the ethylene-unsaturated carboxylic acid copolymer is preferably an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer.

[0049] In the composition of the present disclosure, the content of the ionomer (A) is 70 parts by mass to 99 parts by mass, preferably 72 parts by mass to 97 parts by mass, more preferably 73 parts by mass to 96 parts by mass, even more preferably 74 parts by mass to 95 parts by mass, particularly preferably 75 parts by mass to 94 parts by mass, and most preferably 76 parts by mass to 93 parts by mass, relative to 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B).

[0050] In the composition of the present disclosure, the content of the liquid elastomer (B) is 1 to 30 parts by mass, preferably 3 to 27 parts by mass, more preferably 4 to 27 parts by mass, even more preferably 5 to 25 parts by mass, particularly preferably 6 to 25 parts by mass, and most preferably 8 to 20 parts by mass, relative to 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B).

[0051] In the composition of the present disclosure, the total content of the ionomer (A) and the liquid elastomer (B) is, for example, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more, relative to 100 parts by mass of the composition.

[0052] The details of the ionomer (A) and liquid elastomer (B) in the composition of the present disclosure are the same as those in the golf ball material described above, and therefore will not be described here. In the composition of the present disclosure, it is preferable that the viscosity of the liquid elastomer (B) at 38°C be 0.1 Pa s to 10,000 Pa s, from the viewpoint of achieving excellent flexural rigidity even at low hardness.

[0053] The composition of the present disclosure may contain, as components other than the ionomer (A) and the liquid elastomer (B), various additives such as other thermoplastic resins, tackifier resins, waxes, antioxidants, weather stabilizers, light stabilizers, heat stabilizers, UV absorbers, lubricants, pigments, dyes, inorganic fillers, etc. The composition of the present disclosure may be produced, for example, by blending the ionomer (A), the liquid elastomer (B), and, if necessary, the various additives described above, and melt-kneading the mixture.

[0054] The composition of the present disclosure has excellent flexural rigidity despite its low hardness, and therefore, in addition to the golf ball applications described above, can be used in packaging materials, automobile parts, sporting goods, shoe parts, and the like.

[0055] Hereinafter, embodiments of the present disclosure will be described in more detail using examples, but the embodiments of the present disclosure are not limited to the following examples.

[0056] The raw materials of the golf ball materials used in the examples and comparative examples are shown below in detail.

[0057] - Ionomer (A) obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions - Ionomer 1: Ionomer of ethylene-methacrylic acid-butyl acrylate copolymer (ethylene content: 75% by mass, methacrylic acid content: 8% by mass, isobutyl acrylate: 17%, metal ions: zinc ions, neutralization degree: 65%) - Ionomer 2: Ionomer of ethylene-methacrylic acid copolymer (ethylene content: 85% by mass, methacrylic acid content: 15% by mass, metal ions: zinc ions, neutralization degree: 59%)

[0058] Liquid Elastomer (B) Liquid Elastomer 1: "Kurapren (registered trademark) LIR-30" (Kuraray Co., Ltd.): isoprene-based, Mw = 28,000, viscosity (38°C) 70 Pa·s Liquid Elastomer 2: "Kurapren (registered trademark) LIR-403" (Kuraray Co., Ltd.): isoprene-based (maleic anhydride-modified type), Mw = 30,000, viscosity (38°C) 200 Pa·s Liquid Elastomer 3: "Kurapren (registered trademark) LIR-410" (Kuraray Co., Ltd.): isoprene-based (maleic acid monomethyl ester-modified type), Mw = 41,000, viscosity (38°C) 430 Pa·s

[0059] -Other raw materials- Solid elastomer 1: "Nipol (registered trademark) IR2200" (manufactured by Zeon Corporation): polyisoprene rubber Solid elastomer 2: "Tafmer MH7020" (manufactured by Mitsui Chemicals, Inc.): ethylene-α-olefin copolymer

[0060] Example 1 Ionomer 1 and Liquid Elastomer 1 were weighed out so that 92 parts by weight of Ionomer 1 and 8 parts by weight of Liquid Elastomer 1 per 100 parts by weight of golf ball material were used, and the mixture was supplied to a kneading / extrudability testing device ("Labo Plastomill (registered trademark)", manufactured by Toyo Seiki Seisaku-sho, Ltd.) and kneaded for 10 minutes at a temperature of 180°C with a rotor rotation speed of 50 rpm in a nitrogen atmosphere. The resulting resin compound was then extruded at a resin temperature of 180°C to obtain a sheet of a specified thickness.

[0061] (Measurement) The obtained sheet was subjected to the following measurements and evaluations. The results are shown in Table 1.

[0062] - MFR (g / 10 min) - MFR was measured in accordance with JIS K 7210-1:2014 under conditions of a temperature of 190°C and a load of 2160 g.

[0063] - Flexural rigidity (MPa) - Flexural rigidity was measured in accordance with JIS K 7106 (Olsen type rigidity test).

[0064] - Shore D Hardness - Shore D hardness was measured in accordance with JIS K 7215.

[0065] Examples 2 to 7 and Comparative Examples 1 to 5 Sheets were obtained and measured and evaluated in the same manner as in Example 1, except that the raw materials were blended according to the blending ratios shown in Table 1. The results are shown in Table 1.

[0066]

[0067] As can be seen from the results in Table 1, sheets made from the golf ball material of the present disclosure have excellent flexural rigidity despite their low hardness. Therefore, by using the golf ball material of the present disclosure in at least one of the skin layer, mid layer, and core layer of a golf ball, the golf ball of the present disclosure will have excellent flexural rigidity despite its low hardness. Examples 1 to 4, 6, and 7, which used Ionomer 1, had lower hardness and better flexural rigidity than Comparative Examples 1 to 3 and 5. Furthermore, it can be seen that Example 5, which used Ionomer 2, had lower hardness and better flexural rigidity than Comparative Example 4.

[0068] The disclosure of Japanese Patent Application No. 2024-123727, filed on July 30, 2024, is incorporated herein by reference in its entirety. All publications, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A golf ball material comprising: an ionomer (A) obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions; and a liquid elastomer (B), wherein the content of the ionomer (A) is 70 to 99 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B).

2. The golf ball material according to claim 1, which has a Shore D hardness of 46.0 or less as measured in accordance with JIS K 7215.

3. The golf ball material according to claim 1, wherein the liquid elastomer (B) has a viscosity at 38°C of 0.1 Pa·s to 10,000 Pa·s.

4. The golf ball material according to claim 1, wherein the ethylene-unsaturated carboxylic acid copolymer is an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer.

5. The golf ball material according to claim 4, wherein the ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer is an ethylene-α,β-unsaturated carboxylic acid-isobutyl acrylate copolymer.

6. The golf ball material according to claim 1, wherein at least a portion of the metal ions in the ionomer (A) are monovalent metal ions.

7. The golf ball material according to claim 1, wherein at least a portion of the metal ions in the ionomer (A) are divalent metal ions.

8. The golf ball material according to claim 1, wherein the liquid elastomer (B) is at least one selected from the group consisting of diene-based elastomers, silicone-based elastomers, urethane-based elastomers, and ethylene-α-olefin oligomers.

9. The golf ball material according to claim 1, which has a flexural rigidity of 20.0 MPa or greater as measured in accordance with JIS K 7106.

10. A golf ball comprising the golf ball material according to any one of claims 1 to 9 in at least one of the skin layer, intermediate layer, and core layer.

11. A composition comprising: an ionomer (A) obtained by neutralizing 20% ​​to 90% of the carboxyl groups of an ethylene-unsaturated carboxylic acid copolymer with metal ions; and a liquid elastomer (B), wherein the content of the ionomer (A) is 70 to 99 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B), and the content of the liquid elastomer (B) is 1 to 30 parts by mass per 100 parts by mass of the total content of the ionomer (A) and the liquid elastomer (B).

12. The composition according to claim 11, wherein the ethylene-unsaturated carboxylic acid copolymer is an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer.

13. The composition according to claim 11 or 12, wherein the viscosity of the liquid elastomer (B) at 38°C is 0.1 Pa·s to 10,000 Pa·s.

Images