JP6219571B2 - Golf ball resin composition and golf ball - Google Patents

Description

The present invention relates to a golf ball resin composition and a golf ball using the same.

As a golf ball structure, a one-piece golf ball comprising a golf ball body, a two-piece golf ball having a core and a cover, a center, a core comprising a single intermediate layer covering the center, and a three-piece having a cover covering the core A golf ball, a multi-piece golf ball having a center and a core composed of at least two intermediate layers covering the center and a cover covering the core have been proposed.

As a material constituting the golf ball, an ionomer resin is widely used because a golf ball having high rigidity and a great flight distance can be obtained, and a material having particularly high resilience is demanded. The ionomer resin can improve the resilience by increasing the degree of neutralization. However, since the flexibility is lowered and the feel at impact is deteriorated, it is difficult to achieve both resilience and flexibility. Although the resilience can be improved by blending a large amount of the basic inorganic metal compound to increase the degree of neutralization, the hardness increases and the fluidity also decreases.

Patent Documents 1 and 2 propose to provide a golf ball material excellent in resilience and flexibility by adding a large amount of fatty acid (metal soap) to a highly neutralized ionomer resin. However, since the acid component of the fatty acid consumes metal ions used for neutralization, the effect of high resilience due to high neutralization cannot be sufficiently obtained, and in terms of both the shot feel and resilience of the golf ball. Insufficient flexibility and high resilience. Also, a large amount of metal component is required.

Patent Document 3 discloses a golf ball using an acid polymer having an acid group neutralized by 70% or more and a polyhydric alcohol, and Patent Document 4 discloses an ionomer resin and a molecular weight of 20,000 or less having two or more hydroxyl groups. A golf ball resin composition having a compound is disclosed. Patent Document 5 also mentions that fatty acid derivatives such as alcohol fatty acid esters, glycerin fatty acid esters, and glycol fatty acid esters may be added to a resin composition for golf balls using a thermoplastic resin such as a ternary ionomer. Has been.

However, these technologies still have room for improvement in terms of both flexibility and high resilience. It is also desired to have good fluidity at the same time.

Japanese Patent No. 4128875 Japanese Patent No. 3767683 Japanese Patent Laid-Open No. 2007-90048 Japanese Patent No. 4117466 JP 2001-348467 A

An object of the present invention is to solve the above-mentioned problems and to provide a golf ball resin composition excellent in resilience, flexibility and fluidity. It is another object of the present invention to provide a golf ball excellent in resilience and feel at impact.

The present invention includes (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 3 to 8 carbon atoms. (A-3) Olefin, C3-C8 α, β-unsaturated carboxylic acid and α, β- A ternary copolymer with an unsaturated carboxylic acid ester, and (a-4) an olefin, an α, β-unsaturated carboxylic acid with 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester. The present invention relates to a golf ball resin composition comprising at least one selected from the group consisting of neutralized metal ions of an original copolymer, having a rebound resilience of 45% or more and an ion aggregate radius of 0.40 nm or more. .

The resin composition for golf balls preferably contains (B) a nonionic surfactant. Here, the nonionic surfactant is preferably a polyhydric alcohol type nonionic surfactant. The nonionic surfactant includes a fatty acid ester obtained by reacting a polyhydric alcohol and a fatty acid, an AO adduct of a fatty acid ester obtained by adding an alkylene oxide to the fatty acid ester, the fatty acid and an alkanol. Preference is also given to at least one selected from the group consisting of fatty acid alkanolamides obtained by reacting with amines and alkyl ethers of polyhydric alcohols. Furthermore, as said nonionic surfactant, the fatty acid ester obtained by making a polyhydric alcohol and a C8-C30 fatty acid react is also preferable. Here, as the fatty acid ester, a compound in which a part of the hydroxyl group of the polyhydric alcohol is esterified can be suitably used.

The fatty acid constituting the polyhydric alcohol type nonionic surfactant is preferably an unsaturated fatty acid. Here, as the unsaturated fatty acid, at least one selected from the group consisting of oleic acid, linoleic acid, linolenic acid, elaidic acid, stearic acid, ricinoleic acid, ricinaleic acid, and these branched fatty acids can be suitably used. .

The polyhydric alcohol is preferably at least one selected from the group consisting of glycerin, polyglycerin, saccharides and sugar alcohols.

The nonionic surfactant is selected from the group consisting of glycerol monooleate, glycerol dioleate, glycerol monostearate, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate and sorbitan tetraoleate. At least one is particularly preferred.

The golf ball resin composition preferably contains 10 to 200 parts by mass of the nonionic surfactant with respect to 100 parts by mass of the resin component, and more preferably contains 20 to 200 parts by mass. Moreover, what contains 100 mass parts or less of (C) basic inorganic metal compounds with respect to 100 mass parts of said resin components is preferable.

The present invention relates to a golf ball having a constituent member formed from the golf ball resin composition.
The present invention relates to a golf ball having at least one core and a cover covering the core, wherein at least one of the cores is formed of the golf ball resin composition.
The present invention also relates to a one-piece golf ball in which a golf ball main body is formed from the golf ball resin composition.

According to the present invention, since the resin composition includes a specific resin, has a rebound resilience of 45% or more, and an ion aggregate radius of 0.40 nm or more, it can be softened while suppressing a decrease in resilience. In addition, it is possible to provide a golf ball resin composition that is excellent in resilience, flexibility, and fluidity by lowering the melt viscosity and increasing fluidity. Therefore, a golf ball excellent in resilience and feel at impact can be provided by using the resin composition.

The graph which shows the relationship between the impact resilience of an Example and a comparative example, and an ion aggregate radius (binary ionomer resin system). The graph which shows the relationship between the total neutralization degree of an Example and a comparative example, and an ion aggregate radius (binary ionomer resin system). The graph which shows the relationship between the melt flow rate of an Example and a comparative example, and an ion aggregate radius (binary ionomer resin system). The graph which shows the relationship between the impact resilience of an Example and a comparative example, and an ion aggregate radius (ternary ionomer resin system). The graph which shows the relationship between the total neutralization degree of an Example and a comparative example, and an ion aggregate radius (ternary ionomer resin system). The graph which shows the relationship between the melt flow rate of an Example and a comparative example, and an ion aggregate radius (ternary ionomer resin system).

The resin composition for golf balls of the present invention comprises: (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 metal ion neutralized product of a binary copolymer of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and (a-3) an α, β-unsaturated olefin and 3 to 8 carbon atoms. A terpolymer of a carboxylic acid and an α, 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 It contains at least one selected from the group consisting of neutralized metal ions of terpolymers with saturated carboxylic acid esters, has a rebound resilience of 45% or more, and an ion aggregate radius of 0.1. 40 nm or more.

As described above, it is generally difficult to achieve both good resilience and flexibility of a golf ball material by using a resin component such as an ionomer resin, and at the same time, it has a predetermined high rebound resilience. In addition, by using a material including an ionomer resin having an ion aggregate radius, it is possible to achieve both softening and high resilience, and to lower the melt viscosity and increase the fluidity. The reason why such an effect is exhibited is presumed as follows.

For example, when a nonionic surfactant is added to the ionomer resin, the activator is incorporated into the ionomer resin ion aggregate, and (I) the ion aggregate is finely dispersed to inhibit crystallization of the ethylene chain. (II) It is considered that the restriction of the main chain by the ion aggregate is weakened. And since these functions increase the mobility of the molecular chain of the ionomer resin, it is presumed that both flexibility and resilience are improved. In particular, when a nonionic surfactant having an unsaturated hydrocarbon group instead of a saturated hydrocarbon group is used as the hydrophobic group, a remarkable low hardness and high rebound effect can be obtained. It is presumed that the action of inhibiting oxidization and increasing molecular mobility is more effectively exhibited.

In addition, when a nonionic surfactant is used, the metal component is not consumed as in the case where a fatty acid is added, so the effect of high resilience due to high neutralization can be achieved without using a large amount of metal component. Is sufficiently obtained. Therefore, both flexibility and resilience can be efficiently achieved.

Furthermore, by using a nonionic surfactant, the melt viscosity of the resin composition is lowered and the effect of improving the fluidity is also obtained. This is because the electrostatic attractive force between the active agent and the metal ion is weak. It is assumed that this is because the strength of the cross-linking point due to the ion aggregate is weakened. In this way, although there is a tendency to improve fluidity due to the addition of a nonionic surfactant, etc., it is possible to judge what kind of material is used to improve moldability such as injection molding. difficult. In the present invention, a resin composition comprising an ionomer resin having an ion aggregate radius determined by using small-angle X-ray scattering measurement, small-angle neutron scattering measurement, or the like and having a predetermined high rebound resilience By using, the moldability and the high resilience are further improved, so that it is possible to provide a golf ball material with remarkably excellent flexibility, resilience and fluidity performance.

The impact resilience of the golf ball resin composition of the present invention is 45% or more. Thereby, the golf ball excellent in resilience (flying distance) is obtained. Preferably it is 50% or more, more preferably 55% or more. Although an upper limit is not specifically limited, Usually, it is 100% or less, Preferably it is 99% or less. The rebound resilience is a rebound resilience measured by molding a golf ball resin composition into a sheet shape, and is measured by a measurement method described later.

The golf ball resin composition of the present invention has an ion associated body radius of 0.40 nm or more. The ion aggregate radius of a resin composition containing a resin component such as an ionomer resin is measured by, for example, measuring small-angle X-ray scattering or small-angle neutron scattering of a polymer material containing metal atoms, thereby aggregating metal atoms in the material. It was obtained as ion associate radius _{R g} of clusters of 0.1nm~100μm formed by. In the present invention, as the ion aggregate radius, that is, the ion aggregate radius _Rg increases, the fluidity increases. Therefore, whether or not the material is moldable by measurement such as small angle X-ray scattering and small angle neutron scattering. Can be judged.

(Small angle X-ray scattering measurement)
In the present invention, in order to measure the ion aggregate radius of the resin composition for golf balls, as X-ray scattering measurement, SAXS (Small-Angle X-ray Scattering) is used to measure the scattering intensity by irradiating the resin composition with X-rays. Small-angle X-ray scattering (scattering angle: usually 10 degrees or less) measurement can be suitably employed. In small-angle X-ray scattering, structural information of a substance can be obtained by measuring X-rays that are scattered by irradiating the substance with X-rays, and having a small scattering angle. , Can analyze the regular structure at several nanometer level.

In order to obtain detailed molecular structure information from the SAXS measurement, it is desirable that an X-ray scattering profile with a high S / N ratio can be measured. Therefore, the X-rays emitted from the synchrotron preferably have a luminance of at least 10 ¹⁰ (photons / s / mrad ² / mm ² /0.1% bw) or more. Note that bw represents the band width of X-rays emitted from the synchrotron. Examples of such synchrotrons include beam lines BL03XU and BL20XU of a large synchrotron radiation facility SPring-8 owned by the High Brightness Optical Science Research Center.

The luminance (photons / s / mrad ² / mm ² /0.1% bw) of the X-ray is preferably 10 ¹⁰ or more, more preferably 10 ¹² or more. Although an upper limit is not specifically limited, It is preferable to use the X-ray intensity below the extent that there is no radiation damage.

The number of photons (photons / s) of the X-ray is preferably 10 ⁷ or more, more preferably 10 ⁹ or more. Although an upper limit is not specifically limited, It is preferable to use the X-ray intensity below the extent that there is no radiation damage.

(Small angle neutron scattering measurement)
Further, in the present invention, in order to measure the radius of the ion aggregate of the resin composition for golf balls, SANS (Small-Angle Neutron Scattering small angle neutron) that measures the scattering intensity by irradiating the resin composition with a neutron beam is used as a neutron scattering measurement. Scattering (scattering angle: usually 10 degrees or less)) measurement can be suitably employed. In small-angle neutron scattering, the structure information of a substance can be obtained by measuring a small scattering angle among neutron rays that are scattered by irradiating the substance with a neutron beam, such as a microphase separation structure of a resin composition, Analyze ordered structures at the nanometer level.

In the SANS measurement, a method using a known magnetic structure or deuteration method can be used. When employing the deuteration method, for example, the rubber composition can be swollen with a deuterated solvent, and the resin composition in an equilibrium state in the deuterium solvent can be irradiated with neutrons to measure the scattering intensity. . Here, as the deuterated solvent for swelling the resin composition, deuterated water, deuterated hexane, deuterated toluene, deuterated chloroform, deuterated methanol, deuterated DMSO ((D ₃ C) ₂ S═O ), Deuterated tetrahydrofuran, deuterated acetonitrile, deuterated dichloromethane, deuterated benzene, deuterated N, N-dimethylformamide and the like.

Neutron rays used for neutron scattering measurement such as SANS can be obtained by using a beam line SANS-J of the JRR-3 research reactor owned by the Japan Atomic Energy Agency.

Similar to the SAXS measurement, the neutron flux intensity (neutrons / cm ² / s) of the neutron beam is preferably 10 ³ or more, more preferably 10 ⁴ in that a neutron scattering profile having a high S / N ratio can be obtained. That's it. Although an upper limit is not specifically limited, It is preferable to use the neutron flux intensity below the grade which does not have radiation damage.

(Measurement condition)
In the X-ray and neutron scattering measurement, since the finer molecular structure of the resin composition needs to be measured, the angle range is 0.001 ° ≦ 2θ ≦ 40 ° using the X-ray and neutron beam. It is preferable to measure, more preferably 0.01 ° ≦ 2θ ≦ 30 °.

X-rays scattered in the SAXS measurement are detected by an X-ray detection device, and an image is generated by an image processing device or the like using X-ray detection data from the X-ray detection device.

Examples of the X-ray detector include a two-dimensional detector (X-ray film, nuclear dry plate, X-ray imaging tube, X-ray fluorescence intensifier tube, X-ray image intensifier, X-ray imaging plate, X-ray CCD. , Amorphous body for X-rays, etc.), a line sensor one-dimensional detector can be used. What is necessary is just to select an X-ray detection apparatus suitably according to the kind, state, etc. of the resin composition used as analysis object.

As the image processing apparatus, an apparatus capable of generating a normal X-ray scattering image based on X-ray detection data obtained by the X-ray detection apparatus can be appropriately used.

The SANS measurement can be measured by the same principle as the SAXS measurement. The scattered neutron beam is detected by the neutron beam detection device, and the image is generated by the image processing device using the neutron beam detection data from the neutron beam detection device. Is done. Here, as described above, as the neutron beam detection device, a known two-dimensional detector, a one-dimensional detector, and an image processing device that can generate a known neutron scattering image can be used. Good.

(Method for analyzing scattering intensity curve)
Next, a method for analyzing a scattering intensity curve obtained by X-ray scattering measurement and neutron scattering measurement of the resin composition will be specifically described.
When a SAXS measurement or a SANS measurement is performed on a resin composition containing a metal atom and containing a functional group having a metal coordination ability, for example, by analyzing the obtained scattering intensity curve by the following method, an O.D. The ionic aggregate radius (R _g ) of a cluster (scatterer) of 1 nm to 100 μm can be determined.

The ionic aggregate radius (R _g ) is determined by fitting the scattering intensity curve I _(q) obtained by SAXS measurement under the following conditions using the Yaruso-Cooper or Kinning-Thomas model.
Light source: CuKa (wavelength 1.54 mm)
Angle range: 0.3 ° ≦ 2θ ≦ 10 °

Among the obtained fitting parameters, it is presumed to ion associate radius R _g of the molecular structure of the size of 0.1nm~100μm corresponds to ion associate radius of clusters of metal atoms formed by aggregation. Accordingly, by performing X-ray scattering measurement such as SAXS or neutron scattering measurement such as SANS, and fitting using the Yaruso-Cooper or Kinning-Thomas model, the ion aggregate radius can be measured.

As described above, the golf ball resin composition has an ion aggregate radius of 0.40 nm or more, and is preferably 1.0 nm or more, more preferably 1.6 nm or more from the viewpoint of fluidity. Although an upper limit is not specifically limited, Preferably it is 5.0 nm or less, More preferably, it is 4.0 nm or less.

Next, the components (a-1) to (a-4) used as the resin component (A) in the present invention will be described.
The component (a-1) is a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and the carboxyl group of the copolymer is not neutralized. It is ionic. The component (a-2) is 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, wherein the carboxyl group of the copolymer An ionomer resin that is at least partially neutralized with metal ions can be used.

The component (a-3) is 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, The non-neutralized carboxylic group is not neutralized. The component (a-4) is a metal ion neutralized product of 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. Examples thereof include an ionomer resin in which at least a part of the carboxyl group of the copolymer is neutralized with a metal ion.

In the present invention, “(a-1) a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms” is simply referred to as “binary copolymer”, and “ (A-2) “ionomer resin comprising a neutralized metal ion of a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms” is referred to as “binary ionomer resin”. "(A-3) 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" is simply referred to as a "ternary copolymer. And "(a-4) a metal ion neutralized product of 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" The “ionomer resin comprising” may be referred to as “ternary ionomer resin”.

In the components (a-1) to (a-4), the olefin is preferably an olefin having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, butene, pentene, hexene, heptene and octene. In particular, ethylene is preferred. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid, and acrylic acid or methacrylic acid is particularly preferable. Examples of the α, β-unsaturated carboxylic acid esters include methyl, ethyl, propyl, n-butyl, isobutyl esters such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, and particularly acrylic acid. Esters or methacrylic esters are preferred.

The (a-1) binary copolymer is preferably a binary copolymer of ethylene and (meth) acrylic acid, and the (a-2) binary ionomer resin is preferably ethylene and (meth). A metal ion neutralized product of a binary copolymer with acrylic acid is preferred. As said (a-3) ternary copolymer, the ternary copolymer of ethylene, (meth) acrylic acid, and (meth) acrylic acid ester is preferable, and as said (a-4) ternary ionomer resin, Is preferably a metal ion neutralized product of a terpolymer of ethylene, (meth) acrylic acid and (meth) acrylic acid ester. Here, (meth) acrylic acid means acrylic acid and / or methacrylic acid.

The content of the α, β-unsaturated carboxylic acid component having 3 to 8 carbon atoms in the (a-1) binary copolymer or (a-3) ternary copolymer is preferably 4% by mass. As mentioned above, More preferably, it is 5 mass% or more. Moreover, this content rate becomes like this. Preferably it is 30 mass% or less, More preferably, it is 25 mass% or less.

The melt flow rate (190 ° C., 2.16 kg load) of the (a-1) binary copolymer and (a-3) ternary copolymer is preferably 5 g / 10 min or more, more preferably 10 g / 10 min. As mentioned above, More preferably, it is 15 g / 10min or more. The melt flow rate is preferably 1700 g / 10 min or less, more preferably 1500 g / 10 min or less, still more preferably 1300 g / 10 min or less. If it is 5 g / 10min or more, the fluidity | liquidity of the resin composition for golf balls becomes favorable, and shaping | molding of a structural member becomes easy. Moreover, if it is 1700 g / 10min or less, durability of the obtained golf ball will become more favorable.

Specific examples of the (a-1) binary copolymer are exemplified by trade names, such as trade names “NUCREL (registered trademark)” (for example, “Nucrel N1050H”, “ "Nucleel N2050H", "Nucleel N1110H", "Nucleel N0200H"), "Nucleel N1560" ethylene-methacrylic acid copolymer, trade name "PRIMACOR (registered trademark) 5980I" from Dow Chemical Company And ethylene-acrylic acid copolymers that are commercially available.

Specific examples of the (a-3) ternary copolymer are exemplified by trade names: “Nucrel (registered trademark)” (for example, “Nucrel AN4318” commercially available from Mitsui DuPont Polychemical Co., Ltd.) “Nucrel AN4319”), a trade name “NUCREL” (registered trademark) (for example, “Nucrel AE”) commercially available from DuPont, a trade name “PRIMACOR” commercially available from Dow Chemical (Registered trademark) (for example, “PRIMACOR AT310”, “PRIMACOR AT320”) ”. The (a-1) binary copolymer or (a-3) ternary copolymer may be used alone or in combination of two or more.

The content of the α, β-unsaturated carboxylic acid component having 3 to 8 carbon atoms in the (a-2) binary ionomer resin is preferably 8% by mass or more, more preferably 10% by mass or more. Preferably it is 12 mass% or more. The content is preferably 30% by mass or less, more preferably 25% by mass or less. If it is 8 mass% or more, it will become easy to make the structural member obtained the desired resilience performance. Moreover, if it is 30 mass% or less, the melt viscosity of the structural member obtained will not become high too much, and a moldability will become favorable.

The neutralization degree of the carboxyl group of the (a-2) binary ionomer resin is preferably 15 mol% or more, more preferably 20 mol% or more. The degree of neutralization is preferably 90 mol% or less, more preferably 85 mol% or less. If it is 15 mol% or more, the resilience and durability of the resulting golf ball will be good. On the other hand, if it is 90 mol% or less, the fluidity | liquidity of the resin composition for golf balls will become favorable.

In addition, the neutralization degree of the carboxyl group of the (a-2) binary ionomer resin can be obtained by the following formula.
Degree of neutralization of carboxyl groups of binary ionomer resin = 100 × number of moles of neutralized carboxyl groups in binary ionomer resin / total number of moles of carboxyl groups in binary ionomer resin

Examples of the metal ion that neutralizes at least a part of the carboxyl group of the binary ionomer resin (a-2) include monovalent metal ions such as sodium, potassium, and lithium; magnesium, calcium, zinc, barium, cadmium, and the like A divalent metal ion such as aluminum; a trivalent metal ion such as aluminum; and other ions such as tin and zirconium.

A specific example of the (a-2) binary ionomer resin is exemplified by a trade name, “Himiran (registered trademark)” (for example, Himiran 1555 (Na ), High Milan 1557 (Zn), High Milan 1605 (Na), High Milan 1706 (Zn), High Milan 1707 (Na), High Milan AM 7311 (Mg), High Milan AM 7329 (Zn)) and the like. Furthermore, “Surlyn (registered trademark)” commercially available from DuPont (for example, Surlyn 8945 (Na), Surlyn 9945 (Zn), Surlyn 8140 (Na), Surlyn 8150 (Na), Surlyn 9120 (Zn), Surlyn 9150 (Zn), Surlyn 6120 (Mg), Surlyn 6910 (Mg), Surlyn 7930 (Li), Surlyn 7940 (Li), Surlyn AD8546 (Li)) ”and the like. Examples of ionomer resins commercially available from ExxonMobil Chemical Co., Ltd. include “Iotek (registered trademark)” (for example, Iotech 8000 (Na), Iotech 8030 (Na), Iotech 7010 (Zn), Iotech 7030 ( Zn)) ”and the like. In addition, Na, Zn, Li, Mg, etc. described in parentheses after the trade name indicate the metal species of these neutralized metal ions. As the (a-2) binary ionomer resin, those exemplified may be used singly or as a mixture of two or more.

The bending rigidity of the (a-2) binary ionomer resin is preferably 50 MPa or more, more preferably 70 MPa or more, and further preferably 80 MPa or more. The flexural rigidity is preferably 500 MPa or less, more preferably 400 MPa or less, and still more preferably 350 MPa or less. If the bending rigidity is too low, the rebound of the golf ball tends to decrease and the flight distance tends to decrease, and if the bending rigidity is too high, the durability of the golf ball may decrease.

The melt flow rate (190 ° C., 2.16 kg load) of the binary ionomer resin (a-2) is preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more, still more preferably 1. It is 0 g / 10 min or more. The melt flow rate is preferably 80 g / 10 min or less, more preferably 70 g / 10 min or less, still more preferably 65 g / 10 min or less. If it is 0.1 g / 10 min or more, the fluidity of the resin composition for golf balls becomes good, and for example, a thin layer can be formed. Moreover, if it is 80 g / 10min or less, durability of the obtained golf ball will become more favorable.

The slab hardness of the (a-2) binary ionomer resin is preferably 10 or more in Shore D hardness, more preferably 15 or more, and still more preferably 20 or more. The slab hardness (Shore D hardness) is preferably 75 or less, more preferably 73 or less, and still more preferably 70 or less. If it is 10 or more, the resilience of the resulting component will be good. Moreover, if it is 75 or less, the structural member obtained will not become hard too much and durability of a golf ball will become more favorable.

The content of the α, β-unsaturated carboxylic acid component having 3 to 8 carbon atoms in the (a-4) ternary ionomer resin is preferably 2% by mass or more, more preferably 3% by mass or more. . The content is preferably 30% by mass or less, more preferably 25% by mass or less.

The neutralization degree of the carboxyl group of the (a-4) ternary ionomer resin is preferably 20 mol% or more, more preferably 30 mol% or more. The degree of neutralization is preferably 90 mol% or less, more preferably 85 mol% or less. If it is 20 mol% or more, the resilience and durability of the golf ball obtained using the golf ball resin composition will be good, and if it is 90 mol% or less, the fluidity of the golf ball resin composition will be good. Become good.

In addition, the neutralization degree of the carboxyl group of (a-4) ternary ionomer resin can be calculated | required by a following formula.
Degree of neutralization of carboxyl groups of ternary ionomer resin = 100 × number of moles of neutralized carboxyl groups in ternary ionomer resin / total number of moles of carboxyl groups in ternary ionomer resin

Examples of the metal ion that neutralizes at least a part of the carboxyl group of the (a-4) ternary ionomer resin include the same as those of the (a-2) binary ionomer resin. The (a-4) ternary ionomer resin is preferably neutralized with magnesium ions. By being neutralized with magnesium ions, the impact resilience is increased.

Specific examples of the (a-4) ternary ionomer resin are illustrated by trade names, such as “Himilan (registered trademark)” (for example, Himilan AM7327 (Zn) commercially available from Mitsui DuPont Polychemical Co., Ltd. ), Himiran 1855 (Zn), Himiran 1856 (Na), Himiran AM7331 (Na), etc.). Further, as ternary ionomer resins commercially available from DuPont, “Surlin 6320 (Mg), Surlyn 8120 (Na), Surlyn 8320 (Na), Surlyn 9320 (Zn), Surlyn 9320W (Zn), etc.)” Can be mentioned. Examples of the ternary ionomer resins commercially available from ExxonMobil Chemical Co., Ltd. include “Iotech 7510 (Zn), Iotech 7520 (Zn), etc.)”. In addition, Na, Zn, Mg, etc. described in parentheses after the trade name indicate the type of neutralized metal ion. The (a-4) ternary ionomer resin may be used alone or in combination of two or more.

The bending rigidity of the (a-4) ternary ionomer resin is preferably 10 MPa or more, more preferably 11 MPa or more, and further preferably 12 MPa or more. The flexural rigidity is preferably 100 MPa or less, more preferably 97 MPa or less, and still more preferably 95 MPa or less. If the bending rigidity is too low, the rebound of the golf ball tends to decrease and the flight distance tends to decrease, and if the bending rigidity is too high, the durability of the golf ball may decrease.

The melt flow rate (190 ° C., 2.16 kg load) of the ternary ionomer resin (a-4) is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, still more preferably 0.8. It is 5 g / 10 min or more. The melt flow rate is preferably 70 g / 10 min or less, more preferably 60 g / 10 min or less, still more preferably 55 g / 10 min or less. If it is 0.1 g / 10 min or more, the fluidity of the golf ball resin composition will be good, and the formation of a thin layer will be easy. Moreover, if it is 70 g / 10min or less, durability of the obtained golf ball will become more favorable.

The slab hardness of the (a-4) ternary ionomer resin is preferably 1 or more in Shore D hardness, more preferably 3 or more, and still more preferably 5 or more. The slab hardness (Shore D hardness) is preferably 70 or less, more preferably 65 or less, and still more preferably 60 or less. If it is 1 or more, the resulting structural member will not be too soft, and the resilience of the golf ball will be good. Moreover, if it is 70 or less, the structural member obtained will not become hard too much and durability of a golf ball will become more favorable.

The resin composition for golf balls of the present invention preferably contains (a-3) a ternary copolymer or (a-4) a ternary ionomer resin as the (A) resin component. Thereby, the structural member obtained does not become hard too much and resilience becomes high.

The resin composition for a golf ball of the present invention is preferably an embodiment in which only the components (a-1) to (a-4) described above are contained as the resin component, but within the range not impairing the effects of the present invention. Further, other thermoplastic elastomers and thermoplastic resins may be contained. When other thermoplastic elastomers and thermoplastic resins are contained, the total content of the components (a-1) to (a-4) in the resin component is preferably 50% by mass or more, more preferably 60% by mass or more. More preferably, it is 70 mass% or more.

The resin composition for golf balls of the present invention preferably contains (B) a nonionic surfactant. By adding a nonionic surfactant to the resin component, both softening and high resilience can be achieved, and by using a material having a carbonyl absorption peak on the high wave number side, high fluidity can also be obtained.

In the present invention, the nonionic surfactant is a surfactant having a hydrophilic group such as a hydroxyl group (—OH) or an ether bond (—O—) that does not dissociate in water. Surfactants, polyethylene glycol type nonionic surfactants, perfluoroalkyl polyoxyethylene ether, perfluoroalkenyl polyoxyethylene ether, and the like. Of these, polyhydric alcohol type nonionic surfactants and polyethylene glycol type nonionic surfactants are preferred from the viewpoint of excellent resilience, flexibility and fluidity, and polyhydric alcohol type nonionic surfactants. Activators are particularly preferred.

A polyhydric alcohol type nonionic surfactant is a nonionic surfactant obtained by reacting a polyhydric alcohol, which is a hydrophilic group material such as glycerin, polyglycerin, or sorbitan, with a hydrophobic group material such as a fatty acid. For example, a fatty acid ester obtained by reacting a dihydric or higher polyhydric alcohol and a fatty acid having about 5 to 36 carbon atoms, and further adding an alkylene oxide (AO) such as ethylene oxide (EO) to the fatty acid ester. Examples include AO adducts of fatty acid esters obtained, fatty acid alkanolamides obtained by reacting the fatty acids with alkanolamines, and alkyl ethers of polyhydric alcohols. Here, the above fatty acid ester, AO adduct, fatty acid alkanolamide and alkyl ether are those in which all hydroxyl groups of polyhydric alcohol or alkanolamine are esterified or condensed, and some hydroxyl groups are esterified or condensed. Any of the above-mentioned ones (mono, di, tri, tetra, etc.) may be used, but those partially esterified or condensed are preferred. In addition, the average number of moles of AO added per molecule of fatty acid ester in the case of an AO adduct is 0.5 to 50, preferably 0.5 to 30.

The number of carbon atoms of the fatty acid constituting the polyhydric alcohol type nonionic surfactant such as the fatty acid ester is preferably 8 to 30, preferably 10 to 28, from the viewpoint of excellent resilience, flexibility and fluidity. More preferably, 12 to 26 is even more preferable. Moreover, as this fatty acid, a linear or branched fatty acid is suitable. Furthermore, although both saturated and unsaturated fatty acids can be used, unsaturated fatty acids are preferred from the standpoints that crystallization is inhibited to increase molecular mobility, and the effects of low hardness and high rebound are increased.

Examples of the fatty acid include those derived from natural fats and oils and synthetic ones. Examples of the natural type include those derived from natural fats and oils such as palm oil, beef tallow, rapeseed oil, rice bran oil, and fish oil. Synthetic fatty acids include higher fatty acids having 5 to 36 carbon atoms. It is done. Specifically, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid and their branched fatty acids, etc. Unsaturated fatty acids such as saturated fatty acids, oleic acid, erucic acid, linoleic acid, linolenic acid, elaidic acid, stearic acid, ricinoleic acid, ricinaleic acid, arachidonic acid, paxenoic acid, myristoleic acid, palmitoleic acid, etc. and their branched fatty acids Etc. Of these, unsaturated fatty acids such as oleic acid, erucic acid, linoleic acid, linolenic acid, arachidonic acid, paxenoic acid, myristoleic acid and palmitoleic acid are preferred because of their excellent resilience, flexibility and fluidity. Oleic acid is particularly preferred.

In the polyhydric alcohol constituting the polyhydric alcohol type nonionic surfactant, examples of the dihydric alcohol include aliphatic, alicyclic and aromatic dihydric alcohols having 2 or more carbon atoms. Are (di) ethylene glycol, (di) propylene glycol, 1,2-, 1,3-, 2,3- and 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol (Di) alkylene glycols (alkylene glycols and dialkylene glycols) such as 1,6-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,12-dodecanediol, cyclic groups Low-molecular-weight diol having bis (hydroxymethyl) cyclohexane, bis (hydroxyethyl) benzene, etc.Examples of trihydric or higher polyhydric alcohols such as 3 to 8 valents include, for example, alkane polyols (triols such as trimethylolpropane, glycerin, and hexanetriol, tetrahydric or higher polyvalents such as pentaerythritol, sorbitol, xylitol, and mannitol. Monohydric alcohol), intermolecular or intramolecular dehydrates (polyglycerol such as diglycerin, dipentaerythritol, sorbitan, etc.), saccharides (glucose, fructose, sucrose, etc.), EO adducts of saccharides, EO addition of saccharides Fatty acid esters of sugars, fatty acid esters of sugars, sugar alcohols (alcohols obtained by reducing aldehyde groups and ketone groups of monosaccharides such as triose, tetrose, pentose, hexose, etc. Specifically, triose-derived glycerin, tetrose Eli from Lit, trait, pentose-derived arabit, ribit, xylit, hexose-derived sorbit, mannitol, altrit, galactite, etc.), sugar alcohol EO adduct, sugar alcohol EO adduct fatty acid ester, sugar alcohol fatty acid ester Etc. Of these, glycerin, polyglycerin, saccharides, and sugar alcohols are preferred, and glycerin is particularly preferred from the viewpoint of excellent resilience, flexibility, and fluidity.

Examples of the alkanolamine that constitutes the fatty acid alkanolamide include monoethanolamine, diethanolamine, triethanolamine, mono-n-propanolamine, di-n-propanolamine, tri-n-propanolamine, monoisopropanolamine, and diethanolamine. Isopropanolamine, triisopropanolamine, N-methylethanolamine, N-ethylethanolamine, N-isopropylethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N-cyclohexyldiethanolamine, N-cyclohexyldi Examples include propanolamine, N-benzyldiethanolamine, and N-benzyldipropanolamine.

Specific examples of the polyhydric alcohol type nonionic surfactant include glycerol monolaurate, glycerol monostearate, glycerol monooleate, glycerol dilaurate, glycerol distearate, glycerol dioleate, diglycerol monolaurate, Diglycerin monostearate, diglycerin monooleate, pentaerythritol monolaurate, pentaerythritol monostearate, pentaerythritol monooleate, pentaerythritol dilaurate, pentaerythritol distearate, pentaerythritol dioleate, sorbitan monolaurate, sorbitan Monostearate, sorbitan monooleate, sorbitan dilaurate, sorbitan distearate, sorbitan dioleate, sorbitan Riraureto, sorbitan Tanto Risute Art, sorbitan trioleate, sorbitan tetra monolaurate, sorbitan Thante trustee art, such as sorbitan tetraoleate and the like. Among these, glycerin monooleate, glycerin dioleate, glycerin monostearate, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, sorbitan tetraoleate because of their excellent resilience, flexibility and fluidity. Oleate is preferred. These polyhydric alcohol type nonionic surfactants may be used alone or in combination of two or more.

The polyethylene glycol type nonionic surfactant is a nonionic surfactant obtained by adding ethylene oxide to a hydrophobic group raw material of a surfactant such as higher alcohol and fatty acid. The alkyl group of the hydrophobic group raw material is not particularly limited, but is preferably an alkyl group or alkenyl group having 12 to 18 carbon atoms, and the number of moles of ethylene oxide added is preferably 2 to 40 although it depends on the bonded hydrophobic group.

Examples of the polyethylene glycol type nonionic surfactant include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, and the like. Specific examples include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl. Examples include ether and polyoxyethylene octylphenol. These polyethylene glycol type nonionic surfactants may be used alone or in combination of two or more.

The content of the (B) nonionic surfactant is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more, particularly preferably 30 with respect to 100 parts by mass of the resin component. More than part by mass. The content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, still more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less. Within the above range, the resilience and flexibility can be improved in a balanced manner.

The golf ball resin composition of the present invention may further contain (C) a basic inorganic metal compound. (C) A basic inorganic metal compound is added as needed in order to neutralize the unneutralized carboxyl group of (A) component. Examples of the basic inorganic metal compound (C) include simple metals such as sodium, lithium, potassium, calcium and magnesium, magnesium hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, copper hydroxide and the like. Metal oxides such as magnesium oxide, calcium oxide, zinc oxide and copper oxide; and metal carbonates such as magnesium carbonate, calcium carbonate, sodium carbonate, lithium carbonate and potassium carbonate. These (C) basic inorganic metal compounds may be used alone or in combination of two or more. Among these, magnesium hydroxide, calcium hydroxide, sodium carbonate, lithium carbonate, potassium carbonate, zinc oxide, and copper oxide are suitable as the basic inorganic metal compound (C).

The content of the (C) basic inorganic metal compound is preferably more than 0 parts by mass and more preferably 1 part by mass or more with respect to 100 parts by mass of the resin component. The content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less. When the content is too small, the amount of ion aggregates is small and low repulsion occurs. On the other hand, when the content is too large, durability may be lowered.

In the golf ball resin composition of the present invention, the total neutralization degree represented by the following formula is preferably 20% or more, more preferably 40% or more, and still more preferably 60% or more. The total neutralization degree is preferably 1000% or less, more preferably 800% or less, and still more preferably 600% or less. If it is 20% or more, the amount of ion aggregates is large and high repulsion occurs. If it is 1000% or less, the basic inorganic metal compound is uniformly dispersed and durability is improved.

The total neutralization degree is defined by the following formula.
Total neutralization degree (%) = 100 × [(A) number of moles of cation component of resin component × valence of cation component + (C) number of moles of metal component of basic inorganic metal compound × valence of metal component Number] / [(A) mol number of carboxyl group of resin component]
The cation component, the metal component, and the carboxyl group include the number of moles of the precursor that is not ionized. The amount of the cation component may be determined by neutralization titration, for example.

The resin composition for a golf ball of the present invention further includes a pigment component such as a white pigment (for example, titanium oxide), a blue pigment, a weight adjuster, a dispersant, an anti-aging agent, an ultraviolet absorber, a light stabilizer, and a fluorescent material. Further, a fluorescent brightening agent or the like may be contained within a range that does not impair the performance of the golf ball. Moreover, the resin composition for golf balls of the present invention may use a fatty acid and / or a metal salt thereof in combination as long as the effects of the present invention are not impaired.

Content of the said white pigment (for example, titanium oxide) becomes like this. Preferably it is 0.5 mass part or more with respect to 100 mass parts of resin components, More preferably, it is 1 mass part or more. The content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less. By setting it as 0.5 mass part or more, concealment property can be provided to the obtained golf ball constituent member. On the other hand, if it exceeds 10 parts by mass, the durability of the resulting golf ball may be reduced.

The resin composition for golf balls of the present invention can be obtained, for example, by dry blending the component (A), the component (B), and the component (C) as necessary. Further, the dry blended mixture may be extruded to be pelletized. For dry blending, for example, it is preferable to use a mixer capable of blending pellet-shaped raw materials, and more preferably a tumbler type mixer. For the extrusion, a known extruder such as a single screw extruder, a twin screw extruder, or a twin screw single screw extruder can be used.

In the golf ball resin composition of the present invention, the spin-lattice relaxation time (T1) of ¹³ C nuclei observed by a solid high-resolution carbon nuclear magnetic resonance method (NMR method) is preferably 15 seconds or less. When the decay of the magnetic susceptibility was measured for the ionomer resin by the spin-lattice relaxation time (T1) of ¹³ C nuclei observed by a solid high-resolution carbon nuclear magnetic resonance method (NMR method), this relaxation time (T1) is It is thought to originate from the trans conformation of the ethylene chain. The inventors of the present invention have an ethylene crystal and an ethylene chain constrained layer around an ion aggregate at a site where there is a possibility of adopting trans conformation. The ethylene chain constrained layer was found to correlate with resilience, considering that it can be separated into time components. That is, when the relaxation time (T1) is shortened, the mobility of the ethylene constrained layer is increased and the resilience is improved. In addition, an increase in flexibility can be expected by increasing molecular mobility. Therefore, the resin composition for a golf ball of the present invention has a ¹³ C nucleus spin-lattice relaxation time (T1) observed by a solid high-resolution carbon nuclear magnetic resonance method (NMR method) having the aforementioned short time. preferable.

In addition, the golf ball resin composition of the present invention is stored when measured in a tensile mode using a dynamic viscoelastic device under conditions of an excitation frequency of 10 Hz, a temperature of 12 ° C., and a measurement strain of 0.05%. It is preferable that the elastic modulus E ′ (Pa) and the loss elastic modulus E ″ (Pa) satisfy the following formula.
By satisfying the following formula, the resin composition for a golf ball has high resilience while maintaining softness at a high level. In the following formula, log is a common logarithm.
log (E ′ / E ″ ² ) ≧ −6.55

It is considered that the resilience increases as the storage elastic modulus E ′ (Pa) increases and the loss elastic modulus E ″ (Pa) decreases. Also, as the storage elastic modulus E ′ (Pa) increases, the hardness also increases. In the above equation, the numerator is the first power of the storage elastic modulus E ′, whereas the denominator is the second power of the loss elastic modulus E ″. Rather than increasing the thickness, reducing the loss elastic modulus E ″ means that the effect of improving the resilience is greater. In other words, to increase the resilience without hardening the material, E ″ is decreased and the deformation is reduced. It is thought that it is necessary to reduce the energy loss at the time, but in the present invention, as the molecular mobility is increased as described above, it is possible to smoothly deform with respect to the stress. Will improve It is.

The upper limit of the log (E ′ / E ″ ² ) is not particularly limited, but is preferably −5.24 or less, more preferably −5.40 or less. The log (E ′ / E ″ ² ) is −5.25. This is because the restitution coefficient approaches 1 which is the maximum value. The measurement conditions of the excitation frequency: 10 Hz and the temperature: 12 ° C. are adopted as the measurement conditions for dynamic viscoelasticity based on the following reasons. In the measurement of the coefficient of restitution at 40 m / s, the contact time between the golf ball and the collision rod (metal cylinder) is 500 μsec. When this is considered as one cycle of deformation, it corresponds to deformation of a frequency of several thousand Hz. . The dynamic viscoelasticity measured under the measurement conditions of temperature: room temperature, excitation frequency: several thousand Hz is measured under the measurement conditions of temperature: 12 ° C. and excitation frequency: 10 Hz based on the frequency / temperature conversion rule of general ionomer resins. This corresponds to dynamic viscoelasticity.

The melt flow rate (190 ° C. × 2.16 kg) of the resin composition for golf balls of the present invention is preferably 0.01 g / 10 min or more, more preferably 1 g / 10 min or more, still more preferably 10 g / 10 min or more. The melt flow rate is preferably 150 g / 10 min or less, more preferably 100 g / 10 min or less, still more preferably 80 g / 10 min or less. If it is in the said range, the moldability to a golf ball structural member will be favorable.

The slab hardness of the golf ball resin composition is preferably 5 or more in Shore D hardness, more preferably 7 or more, and still more preferably 10 or more. The slab hardness (Shore D hardness) is preferably 70 or less, more preferably 65 or less, still more preferably 60 or less, and most preferably 50 or less. By using five or more golf ball resin compositions, a golf ball having excellent resilience (flying distance) can be obtained. On the other hand, a golf ball having excellent durability can be obtained by using a golf ball resin composition of 70 or less. Here, the slab hardness of the golf ball resin composition is a hardness measured by molding the golf ball resin composition into a sheet shape, and is measured by a measurement method described later.

The golf ball of the present invention is not particularly limited as long as it has a constituent member formed from the golf ball resin composition. For example, a one-piece golf ball; a two-piece golf ball having a single-layer core and a cover disposed so as to cover the single-layer core; a center and a single-layer intermediate layer disposed so as to cover the center A three-piece golf ball having a core formed of: and a cover disposed so as to cover the core; or a core formed of a center and one or more intermediate layers disposed so as to cover the center. Any of the constituent members constituting a multi-piece golf ball (including the three-piece golf ball) having a cover disposed to cover the core is formed from the golf ball resin composition of the present invention. A golf ball can be mentioned. Among these, a golf ball having at least one core and a cover covering the core, wherein at least one layer of the core is formed from the resin composition for golf balls, or one-piece golf An embodiment in which the golf ball body of the ball is formed from the golf ball resin composition is preferable. In particular, a two-piece golf ball having a single layer core and a cover disposed so as to cover the single layer core, wherein the single layer core is formed from the golf ball resin composition, Or a multi-piece golf ball having a core comprising a center and one or more intermediate layers disposed so as to cover the center, and a cover disposed so as to cover the core; However, the aspect currently formed from the said resin composition for golf balls is preferable.

Hereinafter, an example of the golf ball of the present invention is a two-piece golf ball having a core and a cover disposed so as to cover the core, and the core is formed from the above-described resin composition for golf balls. However, the present invention is not limited to such an embodiment.

The core is molded, for example, by injection molding the above-described golf ball resin composition. Specifically, a golf ball resin composition heated and melted at 160 to 260 ° C. is poured into a mold clamped at a pressure of 1 to 100 MPa in 1 to 100 seconds, and cooled down for 30 to 300 seconds. It is preferable to perform by opening.

The core is preferably spherical. When the shape of the core is not spherical, the thickness of the cover becomes non-uniform, and as a result, there may be a portion where the cover performance is partially reduced.

The core has a diameter of preferably 39.00 mm or more, more preferably 39.25 mm or more, and still more preferably 39.50 mm or more. The diameter is preferably 42.37 mm or less, more preferably 42.22 mm or less, and still more preferably 42.07 mm or less. If it is 39.00 mm or more, the thickness of the cover layer will not be too thick, and as a result, the resilience will be good. On the other hand, if it is 42.37 mm or less, the cover layer does not become too thin, and the protective function of the cover is sufficiently exhibited.

When the core has a diameter of 39.00 to 42.37 mm, the amount of compressive deformation (the amount by which the center contracts in the compression direction) from when the initial load 98N is applied to when the final load 1275N is applied is preferably 1. It is 00 mm or more, more preferably 1.10 mm or more. The amount of compressive deformation is preferably 5.00 mm or less, more preferably 4.90 mm or less, and still more preferably 4.80 mm or less. If it is 1.00 mm or more, the feel at impact is good, and if it is 5.00 mm or less, the resilience is good.

The surface hardness of the core is preferably 20 or more in Shore D hardness, more preferably 25 or more, and still more preferably 30 or more. The surface hardness (Shore D hardness) is preferably 70 or less, and more preferably 69 or less. By setting it to 20 or more, the core does not become too soft and good resilience can be obtained. Moreover, by setting it as 70 or less, a core does not become hard too much and a favorable shot feeling is obtained.

The core has a center hardness of preferably 5 or more in Shore D hardness, more preferably 7 or more, and still more preferably 10 or more. If it is less than 5, it may become too soft and the resilience may decrease. Further, the center hardness of the core is preferably 50 or less in Shore D hardness, more preferably 48 or less, and still more preferably 46 or less. If it exceeds 50, it becomes too hard and the feel at impact tends to be lowered. In the present invention, the center hardness of the core means a hardness measured by a spring type hardness tester Shore D type at a center point of the cut surface by cutting the core into two equal parts.

It is also preferable that the core contains a filler. The filler is mainly blended as a weight regulator for adjusting the density of the golf ball obtained as a final product to a range of 1.0 to 1.5, and may be blended as necessary. Examples of the filler include inorganic fillers such as zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder. The blending amount of the filler is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more with respect to 100 parts by mass of the resin component. The amount is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. If the amount is less than 0.5 parts by mass, it is difficult to adjust the weight. If the amount exceeds 30 parts by mass, the weight fraction of the resin component tends to be small, and the resilience tends to decrease.

The golf ball cover of the present invention is preferably formed from a cover composition containing a resin component. Examples of the resin component include urethane resins such as ionomer resins, polyester resins, thermoplastic urethane resins or two-component curable urethane resins, various resins such as polyamide resins, and trade names “Pebax (registered trademark)” from Arkema Co., Ltd. (For example, “Pebax 2533”), a commercially available thermoplastic polyamide elastomer, commercially available under the trade name “Hytrel® (eg,“ Hytrel 3548 ”,“ Hytrel 4047 ”) from Toray DuPont Co., Ltd. Thermoplastic Polyester Elastomer, a commercially available thermoplastic polyurethane elastomer under the trade name “Elastolan (registered trademark)” (for example, “Elastolan XNY97A”) from BASF Japan, Inc., a product from Mitsubishi Chemical Corporation Marketed under the name "Lavalon (registered trademark)" , And the like thermoplastic styrene elastomer having. You may use the said resin component individually or in mixture of 2 or more types.

As an ionomer resin that can be used for a golf ball cover, it is preferable to use those exemplified as the component (a-2) or the component (a-4).

More preferably, the cover composition constituting the cover of the golf ball contains a polyurethane resin (including a polyurethane elastomer) or an ionomer resin as a resin component. The content of the polyurethane resin or ionomer resin in the resin component of the cover composition is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more.

In addition to the resin component described above, the cover composition includes pigment components such as white pigments (eg, titanium oxide), blue pigments, and red pigments, weight adjusters such as zinc oxide, calcium carbonate, and barium sulfate, dispersants, and aging. An inhibitor, an ultraviolet absorber, a light stabilizer, a fluorescent material, a fluorescent whitening agent, or the like may be contained within a range that does not impair the performance of the cover.

The content of the white pigment (for example, titanium oxide) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the resin component constituting the cover. The content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less. By setting it as 0.5 mass part or more, concealment property can be provided to a cover. Moreover, when it exceeds 10 mass parts, durability of the cover obtained may fall.

The golf ball cover of the present invention may be molded by, for example, a compression molding method (preferably, a cover), in which a hollow shell-shaped shell is molded from a cover composition, and the core is covered with a plurality of shells. A method in which a hollow shell-shaped half shell is molded from the composition for coating and the core is covered with two half shells and compression molded), or an injection molding method in which the cover composition is directly injection molded onto the core. be able to.

When a cover composition is injection molded to form a cover, it may be injection molded using a pellet-shaped cover composition obtained by extrusion in advance, or a cover of a base resin component, pigment, etc. The materials may be dry blended and directly injection molded. As the upper and lower molds for forming the cover, it is preferable to use a cover mold having a hemispherical cavity and having a pimple and also serving as a hold pin in which a part of the pimple can advance and retreat. The cover can be formed by injection molding by projecting the hold pin, inserting the core, holding the cover, injecting the cover composition, and cooling. Specifically, a cover composition heated to 200 to 250 ° C. is injected in a mold clamped at a pressure of 9 to 15 MPa in 0.5 to 5 seconds, cooled for 10 to 60 seconds, and opened. It is preferable to carry out by doing.

When molding a cover, a depression called a dimple is usually formed on the surface. The total number of dimples formed on the cover is preferably 200 to 500. If it is less than 200, the dimple effect is difficult to obtain. On the other hand, if the number exceeds 500, the size of each dimple becomes small, and it is difficult to obtain the dimple effect. The shape (plan view shape) of the dimple formed is not particularly limited, and a circular shape; a polygon such as a substantially triangular shape, a substantially square shape, a substantially pentagonal shape, or a substantially hexagonal shape; Alternatively, two or more kinds may be used in combination.

The cover has a thickness of preferably 2.0 mm or less, more preferably 1.6 mm or less, still more preferably 1.2 mm or less, and particularly preferably 1.0 mm or less. If it is 2.0 mm or less, the resilience and feel at impact of the resulting golf ball will be better. The thickness of the cover is preferably 0.1 mm or more, more preferably 0.2 mm or more, and further preferably 0.3 mm or more. If it is less than 0.1 mm, molding of the cover may be difficult, and the durability and wear resistance of the cover may be reduced.

The golf ball body in which the cover is molded is preferably taken out from the mold and subjected to surface treatment such as deburring, washing, and sandblasting as necessary. Moreover, a coating film and a mark can also be formed if desired. Although the film thickness of a coating film is not specifically limited, 5 micrometers or more are preferable and 7 micrometers or more are more preferable. The film thickness is preferably 25 μm or less, and more preferably 18 μm or less. When the thickness is less than 5 μm, the coating tends to be worn away by continuous use, and when it exceeds 25 μm, the dimple effect is reduced and the flight performance of the golf ball tends to be reduced.

In the golf ball of the present invention, the amount of compressive deformation (the amount of contraction in the compression direction) when a final load of 1275N is applied from a state where an initial load of 98N is applied is preferably 2.0 mm or more, and 2.2 mm or more. More preferred. The amount of compressive deformation is preferably 4.0 mm or less, and more preferably 3.5 mm or less. A golf ball of 2.0 mm or more does not become too hard and has a good shot feeling. On the other hand, when the thickness is 4.0 mm or less, the resilience increases.

While the embodiment in which the golf ball resin composition of the present invention is used for the core has been described above, the golf ball resin composition of the present invention can also be used for the center, the intermediate layer, or the cover. When the center is formed from the golf ball resin composition of the present invention, as the material for forming the intermediate layer, for example, the resin component exemplified as the cover material can be used.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[Evaluation method]
(1) Slab hardness (Shore D hardness)
Using the golf ball resin composition, a sheet having a thickness of about 2 mm was produced by hot press molding and stored at 23 ° C. for 2 weeks. An automatic rubber hardness tester P1 type manufactured by Kobunshi Keiki Co., Ltd. equipped with a spring type hardness tester Shore D type as defined in ASTM-D2240 in a state where three or more sheets are stacked so as not to affect the measurement substrate. It measured using.

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

(3) Rebound resilience (%)
A golf ball resin composition is used to produce a sheet having a thickness of about 2 mm by hot press molding, and by stacking six sheets punched into a circular shape having a diameter of 28 mm from the sheet, the thickness is about 12 mm and the diameter A 28 mm cylindrical test piece was prepared. A Rüpke-type rebound resilience test (test temperature and humidity of 23 ° C., 50 RH%) was performed on this test piece. The test piece was prepared and tested in accordance with JIS K6255.

(4) Compression deformation (mm)
The amount of deformation in the compression direction (the amount by which the spherical body contracts in the compression direction) from when the initial load 98N was applied to the spherical body to when the final load 1275N was applied was measured. The compression deformation of each ball is shown in Table 1 with the ball no. 15 with the amount of compressive deformation, Table 2 shows the ball no. It was shown as a ratio to the amount of compression deformation of 31.

(5) Coefficient of restitution 198.4 g of a metal cylinder collides with each spherical body at a speed of 40 m / sec., And measures the speed of the cylinder and the golf ball before and after the collision. The coefficient of restitution was calculated. The measurement was performed on 12 pieces for each spherical body, and the average value was used as the restitution coefficient of each spherical body.

(6) Feeling of hitting ball 10 amateur golfers (advanced players) performed an actual hitting test using a driver, and evaluated the feeling of each hitting ball according to the following criteria. Of the 10 evaluations, the highest evaluation was the shot feel of the golf ball.
Excellent evaluation criteria: Feeling is good with little impact.
Good: Normal.
Bad: The impact is great and the feeling is bad.

(7) Apparatus for measuring spin-lattice relaxation time (T1) of ¹³ C nuclei observed by solid high-resolution carbon nuclear magnetic resonance (NMR) method: Bruker Avance 400
Measurement method: T1 relaxation time measurement by Torcha method Measurement frequency: 100.6256207 MHz
Measurement temperature: room temperature Reference material: adamantane magic angle rotation speed: 5000 Hz
Pulse width: 4.80 μsec
Contact time: 2000 μsec
Pulse interval: 1 μsec, 100 msec, 500 msec, 1 sec, 2 sec, 3 sec, 4 sec, 6 sec, 8 sec, 10 sec, 12 sec, 15 sec, 20 sec, 40 sec, 80 sec, 120 sec
Magnetic field strength: 9.4T

(8) Measurement of storage elastic modulus E ′ (Pa) and loss elastic modulus E ″ (Pa) The storage elastic modulus E ′ (Pa) and loss elastic modulus E ″ (Pa) of the golf ball resin composition are as follows. Measured with
Apparatus: Dynamic viscoelasticity measuring apparatus Rheogel-E4000 manufactured by UBM Co., Ltd.
Measurement sample: A sheet having a thickness of 2 mm was produced from the resin composition for golf balls by press molding, and a sample piece was cut out from the sheet so as to have a width of 4 mm and a distance between clamps of 20 mm.
Measurement mode: Tensile measurement temperature: 12 ° C
Excitation frequency: 10 Hz
Measurement strain: 0.05%

(9) A plate-shaped sample (resin composition sheet) having a SAXS measurement thickness of about 1 mm was attached to a sample holder, and the sample was irradiated with X-rays at room temperature. The scattering intensity curve obtained from the measurement with BL03XU and the scattering intensity curve obtained from the measurement with BL20XU were combined by the least square method. The combination of the two curves fixed the scattering intensity curve obtained from BL03XU on the wide angle side and shifted the scattering intensity curve obtained from BL20XU on the small angle side. The obtained scattering intensity curve _{I (q),} fitted with Kinning-Thomas model was determined ion associate radius _{R g.}
(SAXS device)
SAXS: SAXS measuring equipment (measurement conditions) attached to the beam lines BL03XU and BL20XU of the large synchrotron radiation facility SPring-8 owned by the High Brightness Optical Science Research Center
X-ray brightness: 5 × 10 ¹² photons / s / mrad ² / mm ² /0.1% bw
X-ray photon count: 2 × 10 ⁹ photons / s
X-ray energy: 8 keV (BL03XU), 23 keV (BL20XU)
Distance from sample to detector: 3m (BL03XU), 160m (BL20XU)
Light source: CuKa (wavelength 1.54 mm)
Angle range: 0.3 ° ≦ 2θ ≦ 10 °
(Detector)
Two-dimensional detector (imaging intensifier and CCD camera)

[Production of spherical body (core)]
As shown in Tables 1 and 2, the blended materials were dry blended, mixed by a twin-screw kneading type extruder, and extruded into cold water in a strand shape. The extruded strand was cut with a pelletizer to prepare a pelletized golf ball resin composition. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D = 35, and the blend was heated to 160-230 ° C. at the die position of the extruder. The obtained pellet-shaped golf ball resin composition was injection molded at 220 ° C. to obtain a spherical body (core) having a diameter of 40 mm.

The raw materials used in Tables 1 and 2 are as follows.
Nukurel AN4319: manufactured by Mitsui DuPont Polychemical Co., Ltd., ethylene / methacrylic acid / butyl acrylate copolymer (melt flow rate (190 ° C. × 2.16 kg): 55 g / 10 min, flexural rigidity: 21 MPa, methacrylic acid content: 8 mass%)
Nukurel N1560: manufactured by Mitsui DuPont Polychemical Co., Ltd., ethylene / methacrylic acid copolymer (melt flow rate (190 ° C. × 2.16 kg): 60 g / 10 min, flexural rigidity: 83 MPa, methacrylic acid content 15% by mass)
Surlyn 6910: manufactured by DuPont, magnesium ion neutralized ethylene-methacrylic acid-butyl acrylate terpolymer (melt flow rate (190 ° C. × 2.16 kg): 0.8 g / 10 min)
Surlyn 6320: DuPont, magnesium ion neutralized ethylene-methacrylic acid-butyl acrylate terpolymer ionomer resin (melt flow rate (190 ° C. × 2.16 kg): 1.0 g / 10 min)
Magnesium hydroxide: glycerin monooleate (oleic acid monoglyceride) manufactured by Wako Pure Chemical Industries, Ltd .: “Riquemar OL-100E” manufactured by Riken Vitamin Co., Ltd.
Glycerol monostearate (stearic acid monoglyceride): “Riquemar S-100” manufactured by Riken Vitamin Co., Ltd.
Sorbitan monooleate: “Poem O-80V” manufactured by Riken Vitamin Co., Ltd.
Sorbitan trioleate: “Riquemar OR-85” manufactured by Riken Vitamin Co., Ltd.

From the results in Table 1, the spherical body No. 2 using the binary ionomer resin system was obtained. Compared to 15-18, sphere monooleate, glycerin monostearate, sorbitan monooleate or sorbitan trioleate is added and sphere No. In Nos. 1 to 14, the resilience was enhanced while the material was softened, and the fluidity was improved as the ion aggregate radius was larger. Furthermore, from the results in Table 2, spherical body No. 3 using a ternary ionomer resin system. The same effect was remarkably exhibited also in 19-34. Therefore, it has been clarified that by using the resin composition of the present invention, it is possible to provide a golf ball excellent in both hit feeling and resilience performance while obtaining good moldability during production.

According to the present invention, a golf ball resin composition excellent in resilience, flexibility and fluidity is obtained, and a golf ball excellent in resilience and feel at impact is provided by using the resin composition. it can.

Claims (14)

(A) (a-1) a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, (a-2) an α, β having 3 to 8 carbon atoms and an olefin. -Neutralized metal ion of binary copolymer with unsaturated carboxylic acid, (a-3) Olefin, C3-8 alpha, beta-unsaturated carboxylic acid and alpha, beta-unsaturated carboxylic acid Ternary copolymer with ester, and (a-4) Ternary copolymer of olefin, C3-8 α, β-unsaturated carboxylic acid and α, β-unsaturated carboxylic acid ester A resin component containing at least one selected from the group consisting of neutralized metal ions of
(B) containing a nonionic surfactant,
Content of the said nonionic surfactant is 70-200 mass parts with respect to 100 mass parts of said resin components,
A golf ball resin composition having a rebound resilience of 45% or more and an ion aggregate radius of 0.40 nm or more. The nonionic surfactant, polyhydric alcohol type nonionic surface active agent in a claim 1 golf ball resin composition. The nonionic surfactant comprises a fatty acid ester obtained by reacting a polyhydric alcohol and a fatty acid, an AO adduct of a fatty acid ester obtained by adding an alkylene oxide to the fatty acid ester, the fatty acid and an alkanolamine. at least one kind of claim 1 golf ball resin composition according selected from the group consisting of alkyl ethers of fatty acid alkanolamides and polyhydric alcohols obtained by reacting. Wherein the nonionic surfactant is a polyhydric alcohol and a fatty acid ester obtained by reacting a fatty acid having 8 to 30 carbon atoms claim 1 golf ball resin composition. The golf ball resin composition according to claim 4 , wherein the fatty acid ester is a compound in which a part of the hydroxyl group of the polyhydric alcohol is esterified. The resin composition for a golf ball according to claim 2 , wherein the fatty acid constituting the polyhydric alcohol type nonionic surfactant is an unsaturated fatty acid. The golf ball according to claim 6 , wherein the unsaturated fatty acid is at least one selected from the group consisting of oleic acid, linoleic acid, linolenic acid, elaidic acid, stearolic acid, ricinoleic acid, ricinaleic acid, and branched fatty acids thereof. Resin composition. The polyhydric alcohols include glycerin, polyglycerin, sugars and golf ball resin composition according to any one of claims 2-7 is at least one selected from the group consisting of sugar alcohols. The nonionic surfactant is at least selected from the group consisting of glycerin monooleate, glycerin dioleate, glycerin monostearate, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate and sorbitan tetraoleate. which is a kind claim 1 golf ball resin composition. The golf ball resin composition according to any one of claims 1 to 9 , comprising 100 parts by mass or less of (C) a basic inorganic metal compound with respect to 100 parts by mass of the resin component. Storage elastic modulus E ′ (Pa) and loss elastic modulus E ″ when measured in a tensile mode using a dynamic viscoelastic device under conditions of an excitation frequency of 10 Hz, a temperature of 12 ° C., and a measurement strain of 0.05%. and (Pa), but the golf ball resin composition according to any one of claims 1 to 10, satisfying the following equation.
−6.18 ≦ log (E ′ / E ″ ² ) ≦ −5.24 Golf balls having a component formed from the golf ball resin composition according to any one of claims 1 to 11. A golf ball comprising at least one core and a cover covering the core, wherein at least one of the cores is formed from the golf ball resin composition according to any one of claims 1 to 11 . ball. A one-piece golf ball in which a golf ball body is formed from the resin composition for golf balls according to any one of claims 1 to 11 .

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