JP6672733B2 - Golf ball resin composition and golf ball - Google Patents

Description

  The present invention relates to a golf ball resin composition containing an ionomer resin.

  As the structure of the golf ball, for example, a two-piece golf ball having a core and a cover, a three-piece golf ball having a core and one intermediate layer covering the core, and a cover covering the intermediate layer, a core and the core A multi-piece golf ball having at least two or more intermediate layers for covering the intermediate layer and a cover for covering the intermediate layer. An ionomer resin is used as a material constituting each layer of a golf ball. The ionomer resin has high rigidity, and when used as a component of a golf ball, a golf ball having a long flight distance can be obtained. For this reason, ionomer resins are widely used as materials for intermediate layers and covers of golf balls.

For example, Patent Document 1 discloses that a storage elastic modulus E ′ (when measured in a tensile mode using a dynamic viscoelastic device under the conditions of an excitation frequency of 10 Hz, a temperature of 12 ° C., and a measured strain of 0.05%). Patent Document 1 (Patent Document 1 (Claim 1)) describes a golf ball resin composition in which Pa) and loss modulus E ″ (Pa) satisfy log (E ′ / E ″ ² ) ≧ −6.08. , Paragraphs 0018, 0057)). Patent Document 2 discloses a golf ball resin composition in which the spin-lattice relaxation time (T1) of ¹³ C nucleus observed by solid-state high-resolution carbon nuclear magnetic resonance (NMR) is 7.3 seconds or less. (See Patent Document 2 (Claim 1, paragraph 0016, 0055)).

  Patent Literature 3 discloses (A) a binary copolymer of (a-1) an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a-2) an olefin and a 3 to 8 carbon atoms. Metal ion neutralized product of a binary copolymer of eight α, β-unsaturated carboxylic acids, (a-3) an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and α, a terpolymer of a β-unsaturated carboxylic acid ester, and (a-4) an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester Golf ball containing at least one selected from the group consisting of metal ion-neutralized terpolymers and (B) a compound having a hydrocarbon chain, a cationic site and an anionic site in its molecule A resin composition for balls is described (see Patent Document 3 (Claim 1, Paragraph 0064)).

  Patent Document 4 discloses (A) a binary copolymer of (a-1) an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a-2) an olefin and a 3 to 8 carbon atoms. Metal ion neutralized product of a binary copolymer of eight α, β-unsaturated carboxylic acids, (a-3) an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and α, a terpolymer of a β-unsaturated carboxylic acid ester, and (a-4) an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester (B) a compound having an unsaturated hydrocarbon chain, a cationic site and an anionic site in the molecule, and C) A golf ball resin composition containing an unsaturated fatty acid is described. 070) reference).

JP 2012-139320 A JP 2012-139321 A JP 2013-78563 A JP 2015-39543 A

  As described above, various resin compositions for golf balls using an ionomer resin have been proposed, but there is room for improvement in resilience. The present invention has been made in view of the above circumstances, and has as its object to provide a golf ball resin composition having excellent resilience.

The golf ball resin composition of the present invention that can solve the above-mentioned problems contains an ionomer resin as a resin component, and is measured by a spin probe method electron spin resonance (spin probe agent; 5-doxyl stearic acid). that the hyperfine coupling constants _{(a zz)} is characterized in that it is a 31.6G～35.0G.

  According to the present invention, a golf ball having excellent resilience can be obtained.

FIG. 1 is a partially cutaway sectional view showing a golf ball according to one embodiment of the present invention. The figure which shows the relationship between the ultrafine coupling constant ( _Azz ) of the resin composition for golf balls, and the rebound resilience. Golf ball resin composition No. 24 ESR spectra.

[Resin composition for golf ball]
The resin composition for a golf ball contains an ionomer resin as a resin component, and has an ultrafine coupling constant ( _Azz ) of 31. measured by electron spin resonance (spin probe; 5-doxyl stearic acid) by a spin probe method. 6 G to 35.0 G.

The spin probe electron spin resonance is a method in which electron spin is introduced into a system to perform electron spin resonance in order to analyze the properties of a diamagnetic substance having no electron spin. 5-Doxyl stearic acid used as a spin probe agent has a stearic acid skeleton and is labeled with doxyl nitroxide at the 5-position. The hyperfine coupling constant (A _zz) are 5 in nitroxides radical hexyl stearate, representing the ultrastructure of nitrogen when the magnetic field is applied in the 2P _z direction N-O. It can be said that the larger the value of the hyperfine coupling constant ( _Azz ), the higher the constraint of doxyl nitroxide.

The ionomer resin is an ionic polymer having an ionic group introduced into a polymer chain. In the ionomer resin, ionic groups are aggregated in a polymer chain matrix to form an ion aggregate. Around the ion association, there is a region where the motion of the polymer chain is restricted. In the ionomer resin, the energy loss at the time of deformation becomes lower as the constraint of the molecular motion around the ion association is higher. Therefore, the resilience of the resin composition for a golf ball is improved as the molecular movement around the ion association is higher. Here, in the resin composition for golf balls, the 5-doxyl stearic acid has a carboxy group portion of a stearic acid skeleton incorporated into an ion associate of an ionomer resin, and a hydrocarbon chain portion is located outside a radial direction of the ion associate. Extend toward you. Therefore, it is considered that doxyl nitroxide of 5-doxyl stearic acid is located around the ion associate. Therefore, the larger the value of the hyperfine coupling constant ( _Azz ) measured by the spin probe method electron spin resonance (spin probe agent: 5-doxyl stearic acid), the higher the constraint of the molecular motion around the ion association becomes. It is considered that the resilience of the resin composition for golf balls is increased.

The hyperfine coupling constant (A _zz ) is 31.6 G or more, preferably 31.8 G or more, more preferably 32.0 G or more, preferably 35.0 G or less, more preferably 34.5 G or less, and still more preferably. Is 34.0 G or less. If the ultrafine coupling constant (A _zz ) is 31.6 G or more, the constraint on the molecular motion around the ion association increases, and the resilience of the golf ball resin composition is improved. For example, the flexibility of the golf ball resin composition itself is maintained and energy loss during deformation is suppressed, so that the resilience of the golf ball resin composition is improved.

When the ionomer resin contains a divalent metal ion (for example, magnesium ion) as a metal ion, the ultrafine coupling constant (A _zz ) is preferably 31.6 G or more, more preferably 31.8 G or more. It is more preferably at least 32.0 G, preferably at most 33.5 G, more preferably at most 33.4 G, even more preferably at most 33.3 G. If the ultrafine coupling constant (A _zz ) is 31.6 G or more, the constraint on the molecular motion around the ion associate increases, and the resilience of the resin composition for golf balls improves. Since the flexibility of the golf ball resin composition itself is maintained and energy loss during deformation is suppressed, the resilience of the golf ball resin composition is improved.

The ionomer resin is, as the metal ions, containing a monovalent metal ion (e.g., sodium ions), the hyperfine coupling constant _{(A zz)} is preferably more than 32.5 g, more preferably 32.8G above, It is more preferably at least 33.1 G, preferably at most 35.0 G, more preferably at most 34.5 G, even more preferably at most 34.0 G. When the ultrafine coupling constant (A _zz ) is 32.5 G or more, the constraint of molecular motion around the ion association increases, the resilience of the resin composition for golf balls improves, and when it is 35.0 G or less. Since the flexibility of the golf ball resin composition itself is maintained and energy loss during deformation is suppressed, the resilience of the golf ball resin composition is improved.

  The slab hardness of the resin composition for golf balls is preferably at least 50, more preferably at least 65, even more preferably at least 75, and preferably at most 99, more preferably at most 95, even more preferably at least Shore C hardness. 90 or less. If the slab hardness is 50 or more in Shore C hardness, deformation when an external force is applied is reduced, and energy loss due to the deformation is suppressed, so that the resilience of the resin composition for golf balls is further improved, and 99 or less. If so, the impact at the time of hitting is suppressed, so that a golf ball with good hit feeling can be manufactured.

  The melt flow rate (MFR) (190 ° C., 2.16 kg) of the resin composition for a golf ball is preferably 0.1 g / 10 min or more, more preferably 0.6 g / 10 min or more, and still more preferably 1.5 g / min. It is 10 min or more, preferably 200 g / 10 min or less, more preferably 60 g / 10 min or less, even more preferably 20 g / 10 min or less. When the MFR is 0.1 g / 10 min or more, the moldability is improved in press molding, injection molding, and the like. When the MFR is 200 g / 10 min or less, variation in fluidity between production batches during golf ball molding is suppressed. Thus, molding defects can be reduced.

  The higher the rebound resilience of the resin composition for golf balls, the better. The upper limit is not limited, but is preferably 50% or more, more preferably 60% or more, and even more preferably 65% or more. When the rebound resilience is 50% or more, the flight distance performance of the obtained golf ball is further improved.

  The resin composition for golf balls contains an ionomer resin as a resin component. Examples of the ionomer resin include an olefin-based ionomer resin, a urethane-based ionomer resin, a styrene-based ionomer resin, and a mixture thereof. As the ionomer resin, an olefinic ionomer resin is preferable.

  Examples of the olefinic ionomer resin include (A1) a metal ion neutralized product of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms (hereinafter referred to as “(A1) binary And / or (A2) a ternary of an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α, β-unsaturated carboxylic acid ester. A metal ion neutralized product of a copolymer (hereinafter sometimes referred to as “(A2) ternary ionomer resin”) is preferred. The (A1) binary ionomer resin and (A2) the ternary ionomer resin are ionomer resins obtained by neutralizing a carboxy group of a copolymer with a metal ion.

  As the olefin, an olefin having 2 to 8 carbon atoms is preferable, and examples thereof include ethylene, propylene, butene, pentene, hexene, heptene, and octene, and ethylene is preferable. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid and the like, and acrylic acid or methacrylic acid is preferable.

  As the α, β-unsaturated carboxylic acid ester, an alkyl ester of α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms is preferable, and an alkyl ester of acrylic acid, methacrylic acid, fumaric acid or maleic acid is more preferable. Particularly, alkyl acrylate or alkyl methacrylate is preferred. Examples of the alkyl group constituting the ester include methyl, ethyl, propyl, n-butyl, isobutyl ester and the like.

  As the (A1) binary ionomer resin, a metal ion neutralized product of an ethylene- (meth) acrylic acid binary copolymer is preferable. As the ternary ionomer resin (A2), a metal ion neutralized product of a ternary copolymer of ethylene, (meth) acrylic acid and (meth) acrylate is preferable. Here, (meth) acrylic acid means acrylic acid and / or methacrylic acid.

  The (A1) binary copolymer constituting the binary ionomer resin, and the (A2) ternary copolymer constituting the ternary ionomer resin are those having 3 to 8 carbon atoms in the copolymer. The content of the α, β-unsaturated carboxylic acid component is preferably 4% by mass or more, more preferably 6% by mass or more, still more preferably 8% by mass or more, preferably 50% by mass or less, more preferably 30% by mass or less. % By mass, more preferably 20% by mass or less, particularly preferably 15% by mass or less. When the content of the α, β-unsaturated carboxylic acid component having 3 to 8 carbon atoms is 4% by mass or more, the binary ionomer resin becomes more resilient, and when the content is 50% by mass or less, the binary ionomer is obtained. The flexibility of the resin is improved.

As the metal ion for neutralizing at least a part of the carboxyl group of the (A1) binary ionomer resin and / or (A2) the ternary ionomer resin, a monovalent metal ion such as sodium, potassium, and lithium is used. Divalent metal ions such as magnesium, calcium, zinc, barium and cadmium; trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The (A1) binary ionomer resin and the (A2) ternary ionomer resin are formed by at least one metal ion selected from the group consisting of Na ⁺ , Mg ²⁺ , Ca ²⁺ , and Zn ^2+. Preferably, they are summed.

  The resin component may contain a thermoplastic resin other than the ionomer resin. In this case, the content of the ionomer resin in the resin component is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. It is also preferable to contain only the ionomer resin as the resin component, and it is particularly preferable to contain only the (A1) binary ionomer resin and / or (A2) the ternary ionomer resin as the resin component.

  Examples of the other thermoplastic resin include, for example, thermoplastic olefin copolymer, thermoplastic polyurethane, thermoplastic polyamide, thermoplastic styrene resin, thermoplastic polyester, thermoplastic acrylic resin, thermoplastic polyolefin, thermoplastic polydiene, and thermoplastic polydiene. A thermoplastic resin such as a plastic polyether is exemplified.

  The golf ball resin composition further includes a pigment component such as a white pigment (for example, titanium oxide) and a blue pigment, a weight adjuster, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material, or a fluorescent material. A whitening agent or the like may be contained in a range that does not impair the performance of the golf ball.

  The content of the white pigment (for example, titanium oxide) is preferably at least 0.5 part by mass, more preferably at least 1 part by mass, preferably at most 10 parts by mass, and preferably at most 8 parts by mass with respect to 100 parts by mass of the resin component. The following is more preferred. When the content of the white pigment is 0.5 parts by mass or more, hiding properties can be imparted to the resulting golf ball component. Further, when the content of the white pigment is 10 parts by mass or less, a decrease in the durability of the obtained golf ball can be suppressed.

  The resin composition for golf balls is preferably obtained by mixing the copolymer composition and (c) the metal compound. The copolymer composition contains, as a resin component, a copolymer having a carboxy group or a sulfo group in a molecule and / or a metal ion neutralized product thereof, and (b1) a betaine-type amphoteric surfactant; (B2) a saturated fatty acid and (b3) at least one selected from the group consisting of unsaturated fatty acids. By mixing a copolymer composition containing at least one of the component (b1), the component (b2) and the component (b3) with the resin component, and the metal compound (c), the ion association becomes (b1) (I) An ionomer resin having a structure in which the component (b2) and / or the component (b3) is incorporated is obtained.

  Examples of the copolymer having a carboxy group or a sulfo group in the molecule and / or a metal ion-neutralized product thereof include (a1-1) an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. Binary copolymer, (a1-2) Metal ion neutralized product of a binary copolymer of olefin and α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a2-1) Olefin and carbon A ternary copolymer of α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester having 3 to 8 carbon atoms, and (a2-2) an olefin and 3 to 8 carbon atoms of α, At least one selected from the group consisting of metal ion neutralized terpolymers of β-unsaturated carboxylic acids and α, β-unsaturated carboxylic acid esters is exemplified.

  A binary copolymer of the (a1-1) olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms (hereinafter sometimes referred to as “(a1-1) binary copolymer”) And / or (a2-1) a ternary copolymer of an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester (hereinafter, referred to as “a”). (A-2) may be referred to as "terpolymer") is a nonionic copolymer in which the carboxyl group in the copolymer is not neutralized.

  The olefin is preferably an olefin having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, butene, pentene, hexene, heptene, octene, and the like, and particularly preferably ethylene. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid and the like, and acrylic acid or methacrylic acid is particularly preferable. As the α, β-unsaturated carboxylic acid ester, for example, methyl, ethyl, propyl, n-butyl, isobutyl ester and the like such as acrylic acid, methacrylic acid, fumaric acid and maleic acid are used. Or a methacrylic acid ester is preferable.

  As the (a1-1) terpolymer, a binary copolymer of ethylene and (meth) acrylic acid is preferable, and as the (a2-1) terpolymer, ethylene and (meth) Ternary copolymers of acrylic acid and (meth) acrylic acid esters are preferred.

  The (a1-1) terpolymer and (a2-1) terpolymer have a content of an α, β-unsaturated carboxylic acid component having 3 to 8 carbon atoms in the copolymer. Is preferably 4% by mass or more, more preferably 6% by mass or more, still more preferably 8% by mass or more, preferably 50% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less. Particularly preferably, the content is 15% by mass or less.

  The MFR (190 ° C., 2.16 kg load) of the (a1-1) terpolymer and (a2-1) terpolymer is preferably 5 g / 10 min or more, more preferably 10 g / 10 min. The above is still more preferably 15 g / 10 min or more, preferably 1700 g / 10 min or less, more preferably 1500 g / 10 min or less, and still more preferably 1300 g / 10 min or less.

  Examples of the (a1-1) binary copolymer include Nucrel (registered trademark) N1050H, N1560, N2050H, N2060, N1108C, N0908C, N1110H, and N0200H (manufactured by Mitsui-DuPont Polychemical Co., Ltd.); Primacol (registered trademark) 5980I (manufactured by Dow Chemical Company). Examples of the (a2-1) terpolymer include Nucrel AN4318 and AN4319 (manufactured by DuPont-Mitsui Polychemicals), Primacol AT310 and AT320 (manufactured by Dow Chemical). The (a1-1) terpolymer and (a2-1) terpolymer may be used alone or in combination of two or more.

  (A1-2) Metal ion neutralized product of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms (hereinafter referred to as “(a1-2) binary ionomer resin And (a2-2) a terpolymer of an olefin, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester. (Hereinafter sometimes referred to as “(a2-2) ternary ionomer resin”) as the above-mentioned (a1-1) binary copolymer or (a2-1) ternary resin What neutralized the carboxy group which a copolymer has with a metal ion is mentioned.

Examples of the metal ion include monovalent metal ions such as sodium, potassium, and lithium; divalent metal ions such as magnesium, calcium, zinc, barium, and cadmium; trivalent metal ions such as aluminum; and tin and zirconium. Other ions are included. The (a1-2) binary ionomer resin and the (a2-2) ternary ionomer resin are at least one selected from the group consisting of Na ⁺ , Mg ²⁺ , Ca ²⁺ , and Zn ²⁺ . It is preferably neutralized with metal ions.

The degree of neutralization of the carboxyl groups of the (a1-2) binary ionomer resin and the (a2-2) ternary ionomer resin is preferably 10 mol% or more, more preferably 15 mol% or more, and still more preferably. Is at least 18 mol%. When the degree of neutralization is 10 mol% or more, the resilience of the obtained golf ball resin composition is further improved. The upper limit of the neutralization degree is not particularly limited, but is 100 mol%, preferably 80 mol%, more preferably 60 mol%. In addition, the neutralization degree of the carboxyl group of the ionomer resin can be obtained by the following equation.
Degree of neutralization (mol%) of ionomer resin = 100 × number of moles of carboxyl groups neutralized in copolymer / total number of moles of carboxyl groups in copolymer

  Examples of the (a1-2) binary ionomer resin include Himilan (registered trademark) 1555 (Na), 1557 (Zn), 1605 (Na), 1706 (Zn), 1707 (Na), AM7311 (Mg), and AM7329. (Zn) (manufactured by DuPont-Mitsui Polychemicals); Surlyn (registered trademark) 8945 (Na), 9945 (Zn), 8140 (Na), 8150 (Na), 9120 (Zn), 9150 (Zn), 6910 (Mg), 6120 (Mg), 7930 (Li), 7940 (Li), AD8546 (Li) (manufactured by DuPont); Iotek (registered trademark) 8000 (Na), 8030 (Na), 7010 (Zn), 7030 (Zn) (manufactured by ExxonMobil Chemical).

  Examples of the (a2-2) ternary ionomer resin include Himilan AM7327 (Zn), 1855 (Zn), 1856 (Na), AM7331 (Na) (manufactured by DuPont-Mitsui Polychemicals); Surlyn 6320 (Mg) , 8120 (Na), 8320 (Na), 9320 (Zn), 9320 W (Zn), HPF1000 (Mg), HPF2000 (Mg) (manufactured by DuPont); Iotek 7510 (Zn), 7520 (Zn) (ExxonMobil Chemical) And the like).

  The resin components of the copolymer composition include (a1-1) a binary copolymer, (a1-2) a binary ionomer resin, (a2-1) a ternary copolymer, and (a2-2). ) A thermoplastic resin other than the ternary ionomer resin may be contained. In this case, (a1-1) a binary copolymer, (a1-2) a binary ionomer resin, (a2-1) a ternary copolymer, and (a2-2) a ternary ionomer in the resin component. The total content of the resin is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. As the resin component, the (a1-1) binary copolymer, (a1-2) binary ionomer resin, (a2-1) ternary copolymer, and / or (a2-2) ternary copolymer It is also preferable to contain only the system ionomer resin, and it is also preferable to contain only the (a1-1) binary copolymer and / or (a2-1) the ternary copolymer.

  Examples of the other thermoplastic resin include, for example, thermoplastic olefin copolymer, thermoplastic polyurethane, thermoplastic polyamide, thermoplastic styrene resin, thermoplastic polyester, thermoplastic acrylic resin, thermoplastic polyolefin, thermoplastic polydiene, and thermoplastic polydiene. A thermoplastic resin such as a plastic polyether is exemplified.

The copolymer composition further contains (b1) a betaine-type amphoteric surfactant, (b2) a saturated fatty acid, and (b3) at least one selected from the group consisting of unsaturated fatty acids. The component (b1), the component (b2) and the component (b3) are formed by the action of a polar group such as a carboxyl group or a betaine-type amphoteric group, so that an ion association site (or its vicinity) in the golf ball resin composition is obtained. Gather in At this time, the alkyl group or the alkenyl group on the opposite side of the polar group site has an effect of restricting the polyolefin site in the resin composition for golf balls (particularly, the polyolefin site around the ion association). That is, these components (b1), (b2) and (b3) have the effect of increasing the constraint on the molecular motion around the ion association and increasing the hyperfine coupling constant ( _Azz ). I have.

  Specific examples of the (b1) betaine-type amphoteric surfactant include alkyldimethylaminoacetic acid betaine (general formula (1)), alkyldihydroxyalkylaminoacetic acid betaine (general formula (2)), and alkylamidoalkyl betaine (general formula (3)), alkylhydroxysulfobetaine (general formula (4)), and alkylcarboxymethylhydroxyethyl imidazolinium betaine (general formula (5)).

In the formula (1), R ¹ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms. In the formula (2), R ²¹ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms, and R ²² and R ²³ each independently represent an alkylene group having 1 to 3 carbon atoms. In the formula (3), R ³¹ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms, and R ³² represents an alkylene group having 1 to 5 carbon atoms. In the formula (4), R ⁴ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms. In the formula (5), R ⁵ represents an alkyl group having 8 to 24 carbon atoms or an alkenyl group having 8 to 24 carbon atoms.

  Examples of the alkyl group having 8 to 24 carbon atoms include linear and branched alkyl groups. Examples of the alkyl group having 8 to 24 carbon atoms include octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, Examples include a henycosyl group, a docosyl group, a tricosyl group, and a tetracosyl group. When the alkyl group having 8 to 24 carbon atoms is branched, those having 3 or less branches are preferable. The alkyl group having 8 to 24 carbon atoms is preferably linear.

  As the alkenyl group having 8 to 24 carbon atoms, a linear or branched alkenyl group may be mentioned. As the alkenyl group having 8 to 24 carbon atoms, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icosenyl, Examples include a henicocenyl group, a docosenyl group, a tricosenyl group, and a tetracosenyl group. Examples of the alkylene group having 1 to 3 carbon atoms include a methylene group, an ethylene group, and a propylene group. Examples of the alkylene group having 1 to 5 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, and a pentylene group.

  Examples of the betaine alkyldimethylaminoacetate include betaine lauryldimethylaminoacetate, betaine oleyldimethylaminoacetate, betaine stearyldimethylaminoacetate and the like.

  The alkyldihydroxyalkylaminoacetic acid betaines include stearyldihydroxymethylaminoacetic acid betaine, stearyldihydroxyethylaminoacetic acid betaine, lauryldihydroxymethylaminoacetic acid betaine, lauryldihydroxyethylaminoacetic acid betaine, myristyldihydroxymethylaminoacetic acid betaine, and behenyldihydroxymethylaminoacetic acid. Betaine, betaine palmityldihydroxyethylaminoacetate, betaine oleyldihydroxymethylaminoacetate and the like.

  Examples of the alkylamidoalkylbetaines include coconut oil fatty acid amidopropylaminoacetic acid betaine and lauric acid amidopropylaminoacetic acid betaine. Examples of the alkylhydroxysulfobetaine include amidopropylhydroxysulfobetaine laurate and coconut oil fatty acid amide dialkylhydroxyalkylsulfobetaine. Examples of the alkyl carboxymethyl hydroxyethyl imidazolinium betaine include 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine.

  When blending the (b1) betaine-type amphoteric surfactant, the content of the (b1) component in the copolymer composition is preferably at least 1 part by mass, more preferably at least 1 part by mass, based on 100 parts by mass of the resin component. It is at least 3 parts by mass, more preferably at least 5 parts by mass, preferably at most 80 parts by mass, more preferably at most 30 parts by mass, even more preferably at most 20 parts by mass. When the content of the component (b1) is 1 part by mass or more, the resilience of the resin composition for golf balls is further improved. When the content is 80 parts by mass or less, deformation when an external force is applied is reduced, and excessive Energy loss due to deformation is suppressed, and the resilience of the resin composition for golf balls is further improved.

  The (b2) saturated fatty acid is not particularly limited as long as it is a fatty acid having no unsaturated bond in a hydrocarbon portion. The saturated fatty acid may be either a straight-chain saturated fatty acid or a branched saturated fatty acid, but is preferably a straight-chain saturated fatty acid in order to increase the affinity with the polyolefin chain site of the resin component as the base resin. In the case of branched saturated fatty acids, those having three or less branches are preferred.

  The (b2) saturated fatty acid is not particularly limited, but is preferably a saturated fatty acid having 4 to 30 carbon atoms, more preferably a saturated fatty acid having 12 to 30 carbon atoms, and 16 to 30 carbon atoms. Is more preferably a saturated fatty acid.

  Specific examples (IUPAC name) of the saturated fatty acid (b2) include butanoic acid (C4), pentanoic acid (C5), hexanoic acid (C6), heptanoic acid (C7), octanoic acid (C8), and nonanoic acid (C9). ), Decanoic acid (C10), undecanoic acid (C11), dodecanoic acid (C12), tridecanoic acid (C13), tetradecanoic acid (C14), pentadecanoic acid (C15), hexadecanoic acid (C16), heptadecanoic acid (C17), Octadecanoic acid (C18), nonadecanoic acid (C19), icosanoic acid (C20), henicosanoic acid (C21), docosanoic acid (C22), tricosanoic acid (C23), tetracosanoic acid (C24), pentacosanoic acid (C25), hexacosanoic acid (C26), heptacosanoic acid (C27), octacosanoic acid (C28), nonacosanoic acid (C29), Like Akontan acid (C30).

  Specific examples (common names) of the (b2) saturated fatty acids include, for example, butyric acid (C4), valeric acid (C5), caproic acid (C6), enanthic acid (C7), caprylic acid (C8), pelargonic acid ( C9), capric acid (C10), lauric acid (C12), myristic acid (C14), pentadecylic acid (C15), palmitic acid (C16), margaric acid (C17), stearic acid (C18), arachidic acid (C20) , Behenic acid (C22), lignoceric acid (C24), cellotic acid (C26), montanic acid (C28), and melicic acid (C30).

  The (b2) saturated fatty acids may be used alone or as a mixture of two or more. Among them, preferred as the (b1) saturated fatty acid are palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid and montanic acid.

  When the (b2) saturated fatty acid is blended, the content of the component (b2) in the copolymer composition is preferably at least 10 parts by mass, more preferably at least 20 parts by mass, based on 100 parts by mass of the resin component. It is more preferably at least 30 parts by mass, preferably at most 150 parts by mass, more preferably at most 100 parts by mass, even more preferably at most 90 parts by mass. When the content of the component (b2) is at least 10 parts by mass, the resilience of the resin composition for golf balls will be further improved. The durability becomes good.

  The (b3) unsaturated fatty acid is not particularly limited as long as it has at least one unsaturated bond in a hydrocarbon chain. Examples of the unsaturated bond include a carbon-carbon double bond and a carbon-carbon triple bond, and a carbon-carbon double bond is preferable from the viewpoint that the molecular chain is easily bent. Examples of the carbon-carbon double bond include a cis-double bond and a trans double bond, and a cis-double bond is more preferable.

  The (b3) unsaturated fatty acid is not particularly limited, but is preferably an unsaturated fatty acid having 4 to 30 carbon atoms, and more preferably an unsaturated fatty acid having 12 to 30 carbon atoms.

  Specific examples (IUPAC name) of the unsaturated fatty acid (b3) include butenoic acid (C4), pentenoic acid (C5), hexenoic acid (C6), heptenoic acid (C7), octenoic acid (C8), and nonenic acid ( C9), decenoic acid (C10), undecenoic acid (C11), dodecenoic acid (C12), tridecenoic acid (C13), tetradecenoic acid (C14), pentadecenoic acid (C15), hexadecenoic acid (C16), heptadecenoic acid (C17) Octadecenoic acid (C18), nonadecenoic acid (C19), icosenoic acid (C20), henicicosenoic acid (C21), docosenoic acid (C22), trichosenoic acid (C23), tetracosenoic acid (C24), pentacosenoic acid (C25), hexacocene Acid (C26), heptacosenoic acid (C27), octacosenoic acid (C28), nonacosenic acid (C29), Riakonten acid (C30) and the like and the like.

  Specific examples (common names) of the unsaturated fatty acids (b3) include, for example, myristoleic acid (C14), palmitoleic acid (C16), stearidonic acid (C18), elaidic acid (C18), vaccenic acid (C18), Oleic acid (C18), linoleic acid (C18), linolenic acid (C18), elaidic acid (C18), gadolinic acid (C20), arachidonic acid (C20), eicosenoic acid (C20), eicosapentaenoic acid (C20), eicosadiene Acid (C20), docosahexaenoic acid (C22), erucic acid (C22), nervonic acid (C24) and the like.

  The unsaturated fatty acids may be used alone or as a mixture of two or more. Among these, (C) the unsaturated fatty acid is preferably palmitoleic acid, oleic acid, linoleic acid or arachidonic acid.

  When the (b3) unsaturated fatty acid is blended, the content of the component (b3) in the copolymer composition is preferably 10 parts by mass or more, more preferably 30 parts by mass, based on 100 parts by mass of the resin component. As described above, the amount is more preferably 50 parts by mass or more, preferably 200 parts by mass or less, more preferably 130 parts by mass or less, and further preferably 100 parts by mass or less. When the content of the component (b3) is at least 10 parts by mass, the resilience of the resin composition for golf balls will be further improved. The durability becomes good.

  An embodiment in which the copolymer composition contains a resin component and a component (b1) and does not contain a component (b2) and a component (b3); a resin component and a component (b2); ) Component and component (b3) are not contained; resin component and component (b3) are contained, component (b1) and component (b2) are not contained; resin component, component (b1) and component (b2) And (b3) component, and does not contain component (b3); an embodiment containing a resin component, component (b1) and component (b3), and does not contain component (b2); resin component and component (b2) An embodiment containing the component (b3) and not containing the component (b1); an embodiment containing a resin component, a component (b1), a component (b2) and a component (b3).

  When the copolymer composition contains (b2) a saturated fatty acid and (b3) an unsaturated fatty acid, the total content thereof is preferably at least 10 parts by mass, more preferably at least 10 parts by mass, based on 100 parts by mass of the resin component. Is at least 30 parts by mass, more preferably at least 50 parts by mass, preferably at most 200 parts by mass, more preferably at most 150 parts by mass, even more preferably at most 130 parts by mass. When the total content is 10 parts by mass or more, the resilience of the resin composition for golf balls is further improved, and when the total content is 200 parts by mass or less, the durability of the components formed from the resin composition for golf balls is good. Becomes

  When the copolymer composition contains (b2) a saturated fatty acid and (b3) an unsaturated fatty acid, the mass ratio ((b2) / (b3)) of these is preferably 0.03 or more, more preferably It is 0.10 or more, more preferably 0.25 or more, preferably 4.0 or less, more preferably 2.0 or less, and still more preferably 1.0 or less. If the mass ratio ((b2) / (b3)) is 0.03 or more, (b3) the effect of improving flexibility derived from unsaturated fatty acids and (b2) the hardness of the constrained region around the ion associate derived from saturated fatty acids. The effect of improving the flexibility can be achieved in a well-balanced manner, and if it is 4.0 or less, the effect of improving the flexibility derived from the unsaturated fatty acid (b3) is further increased.

  The metal compound (c) is added as necessary to neutralize the unneutralized carboxyl groups of the golf ball resin composition. Examples of the metal ions contained in the metal compound (c) include monovalent metal ions such as sodium, potassium, and lithium; divalent metal ions such as magnesium, calcium, zinc, barium, and cadmium; and trivalent metal ions such as aluminum. Metal ions; other ions such as tin and zirconium. Among these, a monovalent or divalent metal ion is preferable.

  Examples of the metal compound (c) include metal hydroxides such as magnesium hydroxide, zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, and copper hydroxide; magnesium oxide, calcium oxide And metal oxides such as zinc oxide and copper oxide; and metal carbonates such as magnesium carbonate, zinc carbonate, calcium carbonate, sodium carbonate, lithium carbonate and potassium carbonate. These (c) metal compounds may be used alone or in combination of two or more.

  The amount of the metal compound (c) may be appropriately adjusted according to the desired total degree of neutralization of the golf ball resin composition. The total degree of neutralization is defined by the following equation.

式中、Σ（樹脂組成物が有する陽イオン成分のモル数×陽イオン成分の価数）は、（ｂ１）ベタイン型両性界面活性剤の陽イオン形成基と陽イオン形成基の価数との積、（ｃ）金属化合物の金属成分のモル数と金属成分の価数との積の合計である。Σ（樹脂組成物が有する陰イオン成分のモル数×陰イオン成分の価数）は、（ｂ１）両性界面活性剤の陰イオン形成基のモル数と陰イオン形成基の価数との積、（ａ１−１）成分、（ａ１−２）成分、（ａ２−１）成分および（ａ２−２）成分のカルボキシル基のモル数、（ｂ２）飽和脂肪酸のカルボキシル基のモル数、（ｂ３）不飽和脂肪酸のカルボキシル基のモル数、の合計である。なお、陽イオン形成基、金属成分、カルボキシル基及び陰イオン形成基には、イオン化していない前駆体を含めるものとする。陽イオン成分量、陽イオン形成基量、陰イオン形成基は、例えば、中和滴定により求めることができる。

In the formula, Σ (the number of moles of the cation component of the resin composition × the valence of the cation component) is (b1) the cation-forming group of the betaine-type amphoteric surfactant and the valence of the cation-forming group. Product, (c) the sum of the product of the number of moles of the metal component of the metal compound and the valence of the metal component. Σ (mol number of anion component of resin composition × valence number of anion component) is (b1) the product of the number of moles of the anion-forming group of the amphoteric surfactant and the valence of the anion-forming group, (A1-1) component, (a1-2) component, (a2-1) component and (a2-2) component carboxyl group mole number, (b2) saturated carboxyl group mole number of saturated fatty acid, (b3) It is the sum of the number of moles of the carboxyl group of the saturated fatty acid. The cation-forming group, metal component, carboxyl group, and anion-forming group include non-ionized precursors. The amount of the cation component, the amount of the cation-forming group, and the amount of the anion-forming group can be determined, for example, by neutralization titration.

  The total degree of neutralization of the golf ball resin composition is preferably 50 mol% or more, more preferably 80 mol% or more, further preferably 100 mol% or more, and preferably 200 mol% or less, more preferably 160 mol% or less. Mol% or less, more preferably 140 mol% or less. If the total degree of neutralization is 50 mol% or more, the amount of ion association increases, and the resilience of the resin composition for golf balls is further improved. The abundance is small, the adverse effect on resilience is reduced, and the resin composition for golf balls has higher resilience.

  The resin composition for a golf ball having the above-mentioned composition includes a resin component containing a component (a1-1), a component (a1-2), a component (a2-1) and / or a component (a2-2); ) A step of melt-mixing at least one of the components (b2) and (b3) to prepare a copolymer composition; and melting the obtained copolymer composition and the component (c). Mixing and preparing a golf ball resin composition. When all the components are mixed at the same time, or after mixing at least one of the components (b1), (b2) and (b3) with the component (c), the mixture is mixed with the resin component. In this case, the component (b1), the component (b2), and the component (b3) are not taken into the ion association of the ionomer resin, and the thickness of the constraining layer cannot be reduced. Moreover, the resin composition for golf balls produced by such a mixing procedure has a high slab hardness and a low rebound resilience.

  In the step of preparing the copolymer composition, the melt mixing can use a kneader or an extruder (a single-screw extruder, a twin-screw extruder, a twin-screw single-screw extruder, or the like). The mixing temperature (material temperature) at the time of preparing the copolymer composition is preferably 140 ° C. or higher, more preferably 160 ° C. or higher, and preferably 220 ° C. or lower, more preferably 200 ° C. or lower.

  In the step of preparing the resin composition for a golf ball, the melt-mixing can use a kneader or an extruder (a single-screw extruder, a twin-screw extruder, a twin-screw single-screw extruder, or the like). The mixing temperature (material temperature) at the time of preparing the copolymer composition is preferably 170 ° C or higher, more preferably 200 ° C or higher, preferably 260 ° C or lower, more preferably 240 ° C or lower.

[Golf ball]
The golf ball has a constituent member formed from the resin composition for a golf ball. The structure of the golf ball is not particularly limited. For example, a two-piece golf ball having a single-layer core and a cover covering the core; one or more intermediate layers covering the core and the core, and covering the intermediate layer Multi-piece golf balls (three-piece golf balls, four-piece golf balls, five-piece golf balls, and the like) having a cover that covers the golf ball.

  The member formed from the golf ball resin composition may be any of a core, an intermediate layer, and a cover, but is preferably an intermediate layer. In the golf ball, conventionally known materials can be used for portions other than the constituent members formed from the golf ball resin composition.

  The core may have a single-layer structure or a multilayer structure. For the core, a known rubber composition (hereinafter sometimes simply referred to as “rubber composition for core”) may be used. For example, a rubber composition containing a base rubber, a co-crosslinking agent and a crosslinking initiator Can be molded by hot pressing.

  As the base rubber, it is particularly preferable to use high cis polybutadiene having a cis bond advantageous for repulsion of 40% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more. As the co-crosslinking agent, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof is preferable, and a metal salt of acrylic acid or a metal salt of methacrylic acid is more preferable. As the metal of the metal salt, zinc, magnesium, calcium, aluminum, and sodium are preferable, and zinc is more preferable. The use amount of the co-crosslinking agent is preferably 20 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the base rubber. When an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms is used as the co-crosslinking agent, it is preferable to mix a metal compound (for example, magnesium oxide). As a crosslinking initiator, an organic peroxide is preferably used. Specifically, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) Organic peroxides such as hexane and di-t-butyl peroxide are exemplified, and among them, dicumyl peroxide is preferably used. The compounding amount of the crosslinking initiator is preferably at least 0.2 part by mass, more preferably at least 0.3 part by mass, preferably at most 5 parts by mass, more preferably at most 5 parts by mass, based on 100 parts by mass of the base rubber. Not more than 3 parts by mass.

  Further, the rubber composition for a core may further contain an organic sulfur compound. As the organic sulfur compound, diphenyl disulfides, thiophenols, and thionaphthols can be suitably used. The amount of the organic sulfur compound is preferably at least 0.1 part by mass, more preferably at least 0.3 part by mass, and preferably at most 5.0 parts by mass, based on 100 parts by mass of the base rubber. Preferably it is 3.0 parts by mass or less. The rubber composition for a core may further contain a carboxylic acid and / or a salt thereof. The carboxylic acid and / or salt thereof is preferably a carboxylic acid having 1 to 30 carbon atoms and / or a salt thereof. As the carboxylic acid, any of an aliphatic carboxylic acid and an aromatic carboxylic acid (such as benzoic acid) can be used. The compounding amount of the carboxylic acid and / or salt thereof is 1 part by mass or more and 40 parts by mass or less based on 100 parts by mass of the base rubber.

  In the core rubber composition, in addition to a base rubber, a co-crosslinking agent, a cross-linking initiator, and an organic sulfur compound, a weight adjusting agent such as zinc oxide or barium sulfate, an antioxidant, and a color powder are appropriately added. Can be blended. Heat press molding conditions of the rubber composition for the core may be appropriately set according to the rubber composition, and are usually heated at 130 ° C to 200 ° C for 10 minutes to 60 minutes, or at 130 ° C to 150 ° C for 20 minutes. After heating for 40 minutes to 160 minutes, it is preferable to perform two-stage heating at 160 ° C. to 180 ° C. for 5 minutes to 15 minutes.

  Examples of the intermediate layer material include thermoplastic resins such as polyurethane resins, ionomer resins, polyamide resins, and polyethylene; thermoplastic elastomers such as styrene elastomer, polyolefin elastomer, polyurethane elastomer, and polyester elastomer; and cured products of rubber compositions. Can be Here, as the ionomer resin, for example, a resin obtained by neutralizing at least a part of carboxyl groups in a copolymer of ethylene and α, β-unsaturated carboxylic acid with a metal ion, or ethylene and α, β-unsaturated carboxylic acid A terpolymer of a saturated carboxylic acid and an α, β-unsaturated carboxylic acid ester in which at least a part of the carboxyl groups is neutralized with a metal ion is exemplified. The intermediate layer may further contain a specific gravity adjuster such as barium sulfate and tungsten, an antioxidant, and a pigment.

  The method for forming the intermediate layer is not particularly limited. For example, a method in which the composition for the intermediate layer is preliminarily formed into a hemispherical shell-like half shell, and two such wrappers are used to wrap the sphere, and are then subjected to pressure molding, or And a method in which the composition for an intermediate layer is directly injection-molded on a sphere to wrap the sphere.

  When the intermediate layer composition is injection-molded onto a sphere to form the intermediate layer, it is preferable to use a molding die having a hemispherical cavity as the upper and lower molds. In the formation of the intermediate layer by injection molding, it is possible to form the intermediate layer by projecting a hold pin, throwing in a coated sphere and holding it, injecting a heated and melted intermediate layer composition, and cooling. it can.

  When the intermediate layer is formed by the compression molding method, the half shell can be formed by either the compression molding method or the injection molding method, but the compression molding method is preferable. The conditions for compression-molding the composition for an intermediate layer into a half shell include, for example, a pressure of 1 MPa or more and 20 MPa or less, and a flow starting temperature of the composition for an intermediate layer of −20 ° C. or more and + 70 ° C. The following molding temperatures can be mentioned. By setting the molding conditions, a half shell having a uniform thickness can be molded. As a method of forming an intermediate layer using a half shell, for example, a method of covering a sphere with two half shells and performing compression molding can be exemplified. The conditions for compression molding the half shell into an intermediate layer include, for example, at a molding pressure of 0.5 MPa or more and 25 MPa or less, with respect to the flow start temperature of the composition for the intermediate layer, -20 ° C. or more and + 70 ° C. The following molding temperatures can be mentioned. By setting the molding conditions, an intermediate layer having a uniform thickness can be molded.

The molding temperature means a maximum temperature at which the surface of the concave portion of the lower mold reaches between the mold clamping and the mold opening. The flow start temperature of the composition was determined by using a “flow tester CFT-500” manufactured by Shimadzu Corporation, and pelletizing the thermoplastic resin composition into a plunger area: 1 cm ² , DIE LENGTH: 1 mm, DIE DIA: 1 mm, It can be measured under the following conditions: load: 588.399 N, starting temperature: 30 ° C., heating rate: 3 ° C./min.

  The thickness of the intermediate layer is preferably at least 0.3 mm, more preferably at least 0.4 mm, still more preferably at least 0.5 mm, preferably at most 2.5 mm, more preferably at most 2.4 mm, even more preferably 2.3 mm or less. In the case of a plurality of intermediate layers, the total thickness of the plurality of intermediate layers is preferably within the above range.

  The cover is the outermost layer of the golf ball body. The cover is formed from a cover composition containing a resin component. The cover material is not particularly limited, and examples thereof include an ionomer resin, polyurethane, polyamide, polyester, and polystyrene, and a polyurethane and an ionomer resin are preferable.

  When a specific example of the cover material is exemplified by a trade name, it is commercially available from Mitsui-DuPont Polychemical Co., Ltd. under the trade name "Himilan (registered trademark)". Ionomer resin, available from BASF Japan Ltd. A thermoplastic polyurethane elastomer marketed under the trade name “Elastolane (registered trademark)”, a thermoplastic polyamide elastomer marketed under the trade name “Pebax (registered trademark)” from Arkema Corporation, and DuPont Toray Co., Ltd. A thermoplastic polyester elastomer commercially available under the trade name "Hytrel (registered trademark)", a thermoplastic styrene elastomer commercially available under the trade name "Lavalon (registered trademark)" from Mitsubishi Chemical Corporation, or a product name "Primalloy" To mention thermoplastic polyester elastomers commercially available in It can be. The cover materials may be used alone or in combination of two or more.

  The cover includes, in addition to the resin components described above, a pigment component such as a white pigment (for example, titanium oxide), a blue pigment, and a red pigment; a specific gravity adjuster such as calcium carbonate and barium sulfate; a dispersant; an antioxidant; An agent, a light stabilizer, a fluorescent material, a fluorescent whitening agent and the like may be contained within a range that does not impair the performance of the cover.

  The mode of molding the cover using the cover composition is not particularly limited, but the mode of injection molding the composition for cover directly onto the core, or the method of molding a hollow shell from the composition for cover, and forming the core (Preferably, a method of forming a hollow shell-shaped half shell from a cover composition, covering the core with two half shells, and compression-molding). Can be. It is preferable that the golf ball body with the cover formed is taken out of the mold and subjected to surface treatment such as deburring, washing, and sand blasting as necessary. Also, if desired, a mark can be formed.

  The thickness of the cover is preferably 4.0 mm or less, more preferably 3.0 mm or less, and still more preferably 2.0 mm or less. When the thickness of the cover is 4.0 mm or less, the resilience and shot feeling of the obtained golf ball are more improved. The thickness of the cover is preferably at least 0.3 mm, more preferably at least 0.5 mm, further preferably at least 0.8 mm, particularly preferably at least 1.0 mm. If the thickness of the cover is less than 0.3 mm, the durability and wear resistance of the cover may be reduced.

  The total number of dimples formed on the cover is preferably 200 or more and 500 or less. If the total number of dimples is less than 200, it is difficult to obtain the effect of dimples. If the total number of dimples exceeds 500, the size of each dimple becomes small, and it is difficult to obtain the effect of the dimple. The shape (planar shape) of the dimple to be formed is not particularly limited, and may be a circle; a polygon such as a substantially triangle, a substantially square, a substantially pentagon, or a substantially hexagon; Or two or more of them may be used in combination.

  It is preferable that the golf ball with the cover formed is taken out of the mold and subjected to a surface treatment such as deburring, washing, and sand blasting as necessary. Further, if desired, a coating film or a mark can be formed. The thickness of the coating film is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. When the film thickness is less than 5 μm, the coating film is liable to be worn out by continuous use, and when the film thickness exceeds 50 μm, the effect of dimples is reduced and the flight performance of the golf ball is reduced.

  The diameter of the golf ball of the present invention is preferably from 40 mm to 45 mm. The diameter is particularly preferably equal to or greater than 42.67 mm from the viewpoint that the standards of the United States Golf Association (USGA) are satisfied. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm, and particularly preferably equal to or less than 42.80 mm. The mass of the golf ball is preferably 40 g or more and 50 g or less. In light of attaining a large inertia, the mass is more preferably equal to or greater than 44 g, and particularly preferably equal to or greater than 45.00 g. In light of satisfying the USGA standard, the mass is particularly preferably equal to or less than 45.93 g.

  When the golf ball of the present invention has a diameter of 40 mm to 45 mm, the amount of compressive deformation (the amount of shrinkage of the golf ball in the compression direction) when a final load of 1275 N is applied from an initial load of 98 N is 2.0 mm or more. It is preferably at least 2.4 mm, more preferably at least 2.5 mm, most preferably at least 2.8 mm, and preferably at most 5.0 mm, more preferably at least 4.0 mm. 5 mm or less. The golf ball having a compression deformation of 2.0 mm or more does not become too hard and has a good shot feeling. On the other hand, by setting the amount of compressive deformation to 5.0 mm or less, the resilience increases.

  FIG. 1 is a partially cutaway sectional view showing a golf ball 1 according to one embodiment of the present invention. The golf ball 1 has a spherical core 2, an intermediate layer 3 disposed outside the spherical core 2, and a cover 4 disposed outside the intermediate layer 3. Many dimples 41 are formed on the surface of the cover 4. Portions of the surface of the cover 4 other than the dimples 41 are lands 42. The intermediate layer 3 is formed from the golf ball resin composition.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples, and changes in a range that does not depart from the gist of the present invention and embodiments of the present invention are all described in the present invention. Included in the range.

[Evaluation methods]
(1) Electron spin resonance The measurement was performed by a spin probe method using an electron spin resonance (ESR) apparatus (manufactured by JEOL, model JES-TE200). As a spin probe agent, 5-doxyl stearic acid (manufactured by Aldrich Chemical Co., Ltd.) was used.

The golf ball resin composition used for the measurement was stored at room temperature for 4 weeks or more after preparation. The resin composition for golf balls was immersed in a 5-doxyl stearic acid aqueous solution (concentration: 1.26 × 10 ⁻⁴ mol / L) at room temperature for 7 days, and then dried at 130 ° C. and 100 Pa for 2 hours. Further, the golf ball resin composition was sandwiched between polyethylene terephthalate (PET) films and pressed at 6.3 MPa to form a sheet having a thickness of about 250 μm. From this sheet, a strip having a width of about 1 mm was cut out to prepare a measurement sample.

  The measurement sample was placed in a 5 mm diameter quartz sample tube and measured. The measurement conditions were as follows: temperature: 20 ° C., microwave frequency: X band, microwave output: 1.0 mW, chart sweep time: 4 min, modulation magnetic field magnitude: 0.1 mT, recorder response: 0.03 s. did.

From the obtained ESR spectrum, the hyperfine coupling constant ( _Azz ) was determined. Specifically, the difference between the magnetic field at the peak top of the convex peak appearing at the lowest magnetic field side and the magnetic field at the peak top of the concave peak appearing at the highest magnetic field side was calculated and divided by two. The difference between the magnetic fields is twice the hyperfine coupling constant ( _Azz ).

(2) Slab hardness A sheet having a thickness of about 2 mm was prepared from the resin composition by injection molding and stored at 23 ° C for 2 weeks. The hardness was measured using an automatic hardness tester (Digest Test II, manufactured by H. Burleys Co., Ltd.) in a state where three or more sheets were stacked so as not to affect the measurement substrate and the like. "Shore C" was used as a detector.

(3) Melt flow rate (MFR) (g / 10 min)
The MFR was measured using a flow tester (Shimadzu Corporation, Shimadzu Flow Tester CFT-100C) according to JIS K7210 (1999). The measurement was performed under the conditions of a measurement temperature of 190 ° C. and a load of 2.16 kg.

(4) Rebound resilience (%)
The rebound resilience test was performed according to JIS K6255 (2013). Using a resin composition, a sheet having a thickness of about 2 mm is prepared by hot press molding (at 170 ° C. for 10 minutes), and six sheets punched out from the sheet into a circular shape having a diameter of 28 mm are stacked. A cylindrical test piece having a diameter of about 12 mm and a diameter of 28 mm was prepared. The test specimen was stored at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5% for 12 hours. The prepared test pieces were measured for the rebound resilience using a Lupke-type rebound resilience test measuring device (manufactured by Kamishima Seisakusho Co., Ltd.). The plane portion of the superposed test piece was supported by a mechanical fixing method, and the measurement conditions were a temperature of 23 ° C., a relative humidity of 50%, a hitting end diameter of 12.50 ± 0.05 mm, and a hitting mass of 0.35 ± 0. 01 kg, and the impact speed was 1.4 ± 0.01 m / s.

(5) Compression deformation (mm)
The amount of deformation in the compression direction (the amount of contraction of the core or golf ball in the compression direction) from the state where an initial load of 98N was applied to the core or the golf ball to the time when a final load of 1275N was applied was measured.

(6) Core hardness (Shore C hardness)
The hardness measured at the surface of the core was defined as the core surface hardness. The core was cut into a hemisphere, and the hardness measured at the center of the cut surface was defined as the core center hardness. The hardness was measured using an automatic hardness meter (manufactured by H. Burleys, Digitest II). "Shore C" was used as a detector.

(7) Restitution coefficient A metal cylinder of 198.4 g collides with each golf ball at a speed of 40 m / sec, and the velocities of the cylinder and the golf ball before and after the collision are measured. Was calculated. The measurement was performed for 12 golf balls, and the average value was defined as the coefficient of restitution of each golf ball.

[Production of resin composition for golf ball]
Golf ball resin composition No. 1 to 23, 26
(A1-1) component, (a1-2) component or (a2-1) component, and (b1) component, (b2) component and / or (b3) so as to have the composition shown in Tables 1 and 2. )) The components were put in a kneader and kneaded at 180 ° C for 30 minutes. Thereafter, the component (c) was added, and the mixture was further kneaded at 220 ° C. for 40 minutes to prepare a resin composition for golf balls, and pelletized using an extruder.

Golf ball resin composition No. 24, 25
The components (a2-1) and (c) were added to obtain the composition shown in Table 2, kneaded at 220 ° C. for 60 minutes to prepare a resin composition for golf balls, and pelletized using an extruder. It has become.

Golf ball resin composition No. 27-31
All the raw materials were simultaneously placed in a kneader and kneaded at 220 ° C. for 60 minutes to prepare a resin composition for golf balls so as to have the composition shown in Table 3, and pelletized using an extruder. The golf ball No. The composition of the intermediate layers of Nos. 27 to 31 is as follows. The composition was the same as that of 2, 8, 10, 15 or 22.

Golf ball resin composition No. 32-36
Component (b1), component (b2) and / or component (b3), and component (c) are placed in a kneader and kneaded at 140 ° C. for 30 minutes so as to obtain the composition shown in Table 3. After pulverizing the solid in a mortar, the component (a1-1) or the component (a2-1) is added, and the mixture is kneaded at 220 ° C. for 40 minutes to prepare a resin composition for golf balls, and is extruded using an extruder. Pelletized. In addition, the resin composition for golf balls No. The composition of each of Nos. 32 to 36 is the same as that of resin composition No. for golf balls. The composition was the same as that of 2, 8, 10, 15 or 22.

Tables 1 to 3 show the evaluation results of the resin compositions for golf balls. FIG. 2 shows the relationship between the ultrafine coupling constant ( _Azz ) and the rebound resilience of each golf ball resin composition. In addition, the resin composition for golf balls No. The ESR spectrum of 24 is shown in FIG.

ニュクレルＡＮ４３１９：三井・デュポン・ポリケミカル社製、エチレン−メタクリル酸−メタクリル酸ブチル共重合体（メタクリル酸の含有率：８質量％、ＭＦＲ（１９０℃、２．１６ｋｇ）：５５ｇ）
ニュクレルＮ１５６０：三井・デュポン・ポリケミカル社製、エチレン−メタクリル酸共重合体（メタクリル酸の含有率：１５質量％、ＭＦＲ（１９０℃、２．１６ｋｇ）：６０ｇ）
ハイミラン（登録商標）ＡＭ７３１１：三井・デュポン・ポリケミカル社製、オレフィンと炭素数３〜８個のα，β−不飽和カルボン酸との二元共重合体のマグネシウムイオン中和物（共重合体の酸含量１５質量％、中和度５０モル％）
オレイン酸：東京化成工業社製
リノール酸：東京化成工業社製
ラウリン酸：東京化成工業社製
パルミチン酸：東京化成工業社製
ステアリン酸：東京化成工業社製
ベヘン酸：東京化成工業社製
オレイルベタイン：ルーブリゾール社製、「Ｃｈｅｍｂｅｔａｉｎｅ ＯＬ」（オレイルジメチルアミノ酢酸ベタイン）の精製品（水分と塩分を除去）
イソステアリン酸：東京化成工業社製（２，２，４，８，１０，１０−ヘキサメチルウンデカン−５−カルボン酸（Ｃ１８））
炭酸ナトリウム：東京化成工業社製
水酸化マグネシウム：和光純薬工業社製

Nucrel AN4319: DuPont-Mitsui Polychemical Co., Ltd., ethylene-methacrylic acid-butyl methacrylate copolymer (methacrylic acid content: 8% by mass, MFR (190 ° C., 2.16 kg): 55 g)
Nuclell N1560: manufactured by Mitsui DuPont Polychemicals, ethylene-methacrylic acid copolymer (methacrylic acid content: 15% by mass, MFR (190 ° C., 2.16 kg): 60 g)
Himilan (registered trademark) AM7311: a neutralized product of a magnesium ion of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms (manufactured by Mitsui DuPont Polychemicals Co., Ltd.) Acid content of 15 mass%, degree of neutralization 50 mol%)
Oleic acid: Tokyo Chemical Industry Co., Ltd. Linoleic acid: Tokyo Chemical Industry Co., Ltd. Lauric acid: Tokyo Chemical Industry Co., Ltd. Palmitic acid: Tokyo Chemical Industry Co., Ltd. Stearic acid: Tokyo Chemical Industry Co., Ltd. Behenic acid: Tokyo Chemical Industry Co., Ltd. Oleyl betaine : Purified product of "Chembetaine OL" (betaine oleyl dimethylaminoacetate) manufactured by Lubrizol (removal of water and salt)
Isostearic acid: Tokyo Chemical Industry Co., Ltd. (2,2,4,8,10,10-hexamethylundecane-5-carboxylic acid (C18))
Sodium carbonate: manufactured by Tokyo Chemical Industry Co., Ltd. Magnesium hydroxide: manufactured by Wako Pure Chemical Industries, Ltd.

Golf ball resin composition No. 1 to 23, 31 and 36 are ionomer resins (neutralized magnesium ion of ethylene-methacrylic acid-butyl methacrylate copolymer, neutralized magnesium ion of ethylene-methacrylic acid copolymer, ethylene- contains sodium ion neutralized product) of methacrylic acid copolymer, hyperfine coupling constants measured by ESR _{(a zz)} is 31.6G～35.0G. These golf ball resin compositions have high rebound resilience.

Golf ball resin composition No. The golf ball resin composition 24～30,32～35 is the hyperfine coupling constant measured by ESR _{(A zz)} of less than 31.6 g, rebound resilience is poor. In addition, the resin composition for golf balls No. Nos. 27 to 36 are golf ball Nos. Same as 2, 8, 10, 15 or 22, but the manufacturing process is different, resulting in a different value for the hyperfine coupling constant ( _Azz ).

[Production of golf ball]
(1) Production of Spherical Core A rubber composition for a core having the composition shown in Table 4 was kneaded with a kneading roll, and heated and pressed in an upper and lower mold having a hemispherical cavity at 170 ° C. for 20 minutes to obtain a spherical core. . In addition, barium sulfate was added in an appropriate amount so that the mass of the obtained golf ball became 45.4 g.

ポリブタジエンゴム：ＪＳＲ社製、「ＢＲ７３０（シス結合含有率：９５質量％）」
アクリル酸亜鉛：シグマ・アルドリッチ社製
ジクミルパーオキサイド：東京化成工業社製
２−チオナフトール：東京化成工業社製

Polybutadiene rubber: manufactured by JSR, "BR730 (cis bond content: 95% by mass)"
Zinc acrylate: Sigma-Aldrich dicumyl peroxide: Tokyo Chemical Industry Co., Ltd. 2-thionaphthol: Tokyo Chemical Industry Co., Ltd.

(2) Preparation of Intermediate Layer An intermediate layer (1 mm thick) covering the core was formed by injection molding the resin composition for golf balls on a spherical core. The resin composition for a golf ball is heated to 200 ° C. to 260 ° C. in a cylinder portion of an injection device, injected into a mold clamped at a pressure of 15 MPa, cooled for 30 seconds, and opened to form an intermediate layer. The sphere was removed.

(3) Production of cover Using the blending materials shown in Table 5, mixing was performed by a twin-screw kneading extruder to prepare a pellet-shaped cover composition. Extrusion conditions for the cover composition were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D = 35, and the compound was heated to 160 to 230 ° C. at a die position of an extruder.

熱可塑性ポリウレタン：ＢＡＳＦジャパン社製、エラストラン（登録商標） ＸＮＹ８５Ａ
酸化チタン：石原産業社製、Ａ２２０

Thermoplastic polyurethane: ELASTTRAN (registered trademark) XNY85A manufactured by BASF Japan Ltd.
Titanium oxide: A220, manufactured by Ishihara Sangyo Co., Ltd.

  At the time of forming the cover, the hold pin is pushed out, the sphere on which the intermediate layer is formed is thrown in after holding, and the cover composition heated to 260 ° C. is injected into the mold clamped with a pressure of 80 tons in 0.3 seconds. After cooling for 30 seconds, the mold was opened and the golf ball was taken out. After the surface of the obtained golf ball body is sandblasted and marked, a clear paint is applied and the paint is dried in an oven at 40 ° C. to obtain a golf ball having a diameter of 42.7 mm and a mass of 45.4 g. Was. Tables 1 to 3 show the evaluation results of the obtained golf balls.

Golf ball No. 1-23, 31 and 36, the intermediate layer is made of an ionomer resin (neutralized magnesium ion of ethylene-methacrylic acid-butyl methacrylate copolymer, neutralized magnesium ion of ethylene-methacrylic acid copolymer, ethylene - contains sodium ion neutralized product) of methacrylic acid copolymer, hyperfine coupling constants _{(a zz)} is formed from a resin composition for a golf ball is 31.6G～35.0G. These golf balls have excellent resilience.

Golf ball No. 24～30,32～35 is hyperfine coupling constant for the golf ball resin composition constituting the intermediate layer _{(A zz)} is less than 31.6 g. These golf balls have poor resilience.

1: golf ball, 2: spherical core, 3: intermediate layer, 4: cover, 41: dimple, 42: land

Claims (8)

As the resin component, (A1) a metal ion neutralized product of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and / or (A2) an olefin and 3 carbon atoms A golf ball resin composition containing an ionomer resin containing a metal ion neutralized product of a ternary copolymer of up to eight α, β-unsaturated carboxylic acids and α, β-unsaturated carboxylic acid esters So ,
The golf ball resin composition is obtained by mixing a copolymer composition and (c) a metal compound,
The copolymer composition comprises, as a resin component, a (a1-1) olefin and a binary copolymer of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and (a1-2) an olefin and carbon Metal ion neutralized product of a binary copolymer of α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a2-1) olefin and α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms Terpolymers of α, β-unsaturated carboxylic acid esters with α, β-unsaturated carboxylic acid esters and (a2-2) olefins and α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms (B1) a betaine-type amphoteric surfactant, (b2) a saturated fatty acid, and (b3) a betaine-type amphoteric surfactant containing at least one selected from the group consisting of a metal ion neutralized product of a terpolymer with an acid ester. ) At least one selected from the group consisting of unsaturated fatty acids,
The ionomer resin contains a divalent metal ion as a metal ion,
Spin probe technique electron spin resonance; hyperfine coupling constants measured by (spin probe agent 5 Doxil monostearate) _{(A zz)} resin composition for golf balls, which is a 31.6G~ 33.5 G Stuff. As the resin component, (A1) a metal ion neutralized product of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and / or (A2) an olefin and 3 carbon atoms A golf ball resin composition containing an ionomer resin containing a metal ion neutralized product of a ternary copolymer of up to eight α, β-unsaturated carboxylic acids and α, β-unsaturated carboxylic acid esters So ,
The golf ball resin composition is obtained by mixing the copolymer composition and (c) a metal compound,
The copolymer composition comprises, as a resin component, a (a1-1) olefin and a binary copolymer of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and (a1-2) an olefin and carbon Metal ion neutralized product of a binary copolymer of α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a2-1) olefin and α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms Terpolymers of α, β-unsaturated carboxylic acid esters with α, β-unsaturated carboxylic acid esters and (a2-2) olefins and α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms (B1) a betaine-type amphoteric surfactant, (b2) a saturated fatty acid, and (b3) a betaine-type amphoteric surfactant containing at least one selected from the group consisting of a metal ion neutralized product of a terpolymer with an acid ester. ) At least one selected from the group consisting of unsaturated fatty acids,
The ionomer resin contains a monovalent metal ion as a metal ion,
Spin probe technique electron spin resonance; golf ball resin composition, wherein the hyperfine coupling constant _{(A zz)} is measured is 32.5G~35.0G by (spin probe agent 5 Doxil acid) . The copolymer composition contains (b2) a saturated fatty acid and (b3) an unsaturated fatty acid,
The resin for a golf ball according to claim 1 or 2 , wherein the total content of the (b2) saturated fatty acid and the (b3) unsaturated fatty acid is 10 parts by mass to 200 parts by mass with respect to 100 parts by mass of the resin component. Composition. The copolymer composition contains (b2) a saturated fatty acid and (b3) an unsaturated fatty acid,
The mass ratio ((b2) / (b3)) of the (b2) saturated fatty acid and the (b3) unsaturated fatty acid is 0.03 to 4.0, and is any one of Claims 1-3. Resin composition for golf balls. The resin composition for a golf ball according to any one of claims 1 to 4, wherein the resilience of the resin composition for a golf ball is 50% or more .   The resin composition for a golf ball according to claim 5, wherein the total degree of neutralization of the resin composition for a golf ball is 50 mol% to 200 mol%.   A golf ball comprising a constituent member formed from the resin composition for a golf ball according to claim 1. A golf ball having a core, at least one intermediate layer covering the core, and a cover covering the intermediate layer,
A golf ball, wherein at least one of the intermediate layers is formed from the golf ball resin composition according to any one of claims 1 to 6.

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