Golf ball

Abstract

To provide a golf ball having improved surface abrasion resistance and contamination resistance in a bunker shot, and is well-balanced in the total performance of carry performance.SOLUTION: A golf ball 1 includes a spherical core 2, an intermediate layer 3, a cover 4, and a paint film 5. Center hardness (H0), hardness at 5, 10, and 15 mm from the center (H5, H10, H15), and surface hardness (Hs) of the spherical core 2 satisfy a predetermined relationship. Thickness of the intermediate layer is 0.70 mm or more and less than 1.30 mm. The cover 4 is formed of a material with loss modulus (E"-40) 6.50×107-22.0×107 Pa and loss modulus (E"-20) 3.50×107-7.10×107 Pa. The paint film 5 is formed of resin in which stress (M10(kgf / cm2)) at 10% strain, and strain (ε1(%)) at stress 0 kgf / cm2 in the deformation decrease satisfy a relationship of 0.10≤ε1 / M10≤1.00. An amount of compressive deformation of the golf ball is 2.00 mm or more, and less than 2.70 mm.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a golf ball having a golf ball body with a spherical core, a mid layer and a cover, and a coating provided on the surface of the golf ball body. [Background technology]

[0002] In order to achieve better scores in competitive golf, professional golfers and advanced golfers are seeking golf balls with excellent overall performance. Specifically, they are seeking golf balls that have a high initial velocity and a low spin rate for driver shots in order to improve distance, and a high spin rate for middle iron shots, short iron shots, and approach shots (particularly when the ball is on turf) in order to improve control. For example, Patent Documents 1 and 2 describe golf balls that achieve both long driver shot distance and good spin performance for approach shots (particularly when the ball is on turf) and middle iron shots by controlling the hardness distribution of the spherical core.

[0003] Patent Document 1 describes a golf ball having a spherical core and a cover positioned on the outside of the spherical core, in which the center hardness (Shore C hardness) of the spherical core, the hardness (Shore C hardness) at points 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm from the center of the spherical core toward the surface, and the surface hardness (Shore C hardness) of the spherical core are respectively classified as H0, H 2.5 , H5, H 7.5 , H 10 , H 12.5 , H 15 , Hs, a golf ball is disclosed which is characterized by satisfying the following relationship (see Patent Document 1 (Claim 1, paragraph 0011)). (H 2.5 -H0)>(H 12.5 -H 10 )>(Hs-H 15 ) (H 10 -H0)≧7 0≦(Hs-H 15 )≦5

[0004] Patent Document 2 describes a golf ball having a spherical core and a cover enclosing the spherical core, characterized in that when a line extending from the center of the spherical core to the surface is divided into eight equal parts, the center hardness (C0), the hardness at 12.5% ​​from the center (C1), the hardness at 25.0% from the center (C2), the hardness at 37.5% from the center (C3), the hardness at 50.0% from the center (C4), the hardness at 62.5% from the center (C5), the hardness at 75.0% from the center (C6), the hardness at 87.5% from the center (C7), and the surface hardness (C8) of the spherical core satisfy the following relationships in Shore C hardness (see Patent Document 2 (Claim 1, paragraphs 0009 and 0010)). 0<(C1-C0)≦6.0, 0<(C2-C1)≦6.0, 0<(C3-C2)≦6.0, 0<(C4-C3)≦6.0, 5.0≦(C5-C4), 0<(C6-C5)≦3.5, 0<(C7-C6)≦3.5, 0<(C8-C7)≦3.5, 1.0≦{(C5-C4)-(C4-C3)} [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-177977 [Patent Document 2] Japanese Patent Publication No. 2023-174165 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, there is a demand for golf balls with excellent overall performance, but there is still room for improvement in terms of achieving both distance on driver shots and spin performance on approach shots (especially when the ball is on the turf) and middle iron shots. Furthermore, in competitive golf, wear and dirt on the surface of the golf ball also affect the score, so golf balls are also required to have excellent wear resistance and contamination resistance.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a golf ball that has improved surface abrasion resistance and contamination resistance on shots from bunkers, and that has a well-balanced overall performance including spin performance on approach shots from the rough (when the ball is biting into the grass), spin performance on middle iron shots, and distance performance on driver shots. [Means for solving the problem]

[0008] The golf ball of the present invention, which has been able to solve the above problems, is a golf ball having a golf ball body including a spherical core, a mid layer enclosing the spherical core, and a cover enclosing the mid layer, and a coating film provided on the surface of the golf ball body, wherein the spherical core has a center hardness (H0), a hardness (H5) at a point 5.0 mm radially from the center of the spherical core, and a hardness (H 10 ), hardness at a radial distance of 15 mm from the center of the spherical core (H 15 ) and surface hardness (Hs) in Shore C hardness satisfy the relationships of the following formulas (1) to (3), the thickness of the intermediate layer is 0.70 mm or more and less than 1.30 mm, and the cover has a loss modulus (E") at a measurement temperature of -40°C measured using a dynamic viscoelasticity device. -40 ) is 6.50×10 7 Pa~22.0×10 7 Pa, and the loss modulus (E -20 ) is 3.50×10 7 Pa ~ 7.10 x 10 7In a tensile test, a test piece is deformed until the strain reaches a predetermined value εmax, and then the stress is reduced to 0 kgf / cm 2 The deformation is reduced until the stress at 10% strain is M10 (kgf / cm 2 ) and the stress when the deformation is reduced is 0 kgf / cm 2 The golf ball is formed from a paint resin that satisfies the relationship 0.10≦ε1 / M10≦1.00, where ε1 (%) is the strain at this time, and the golf ball is characterized in that the amount of compressive deformation when an initial load of 98 N is applied and a final load of 1275 N is applied is 2.00 mm or more and less than 2.70 mm. -3.0≦{(H5-H0)-(H 15 -H 10 )}≦3.0 (1) -3.0≦{(H 10 -H5)-(H s -H 15 )}≦3.0 (2) 5.0≦[{(H5-H0)+(H 15 -H 10 )} / 2-{(H 10 -H5)+(Hs-H 15 )} / 2]≦10.0 (3)

[0009] The spherical core has a predetermined hardness distribution, which allows for a good balance of overall performance in terms of distance on driver shots, spin rate on middle iron shots, and approach shots (especially when the ball is biting into the grass). By setting the thickness of the intermediate layer to be equal to or greater than 0.70 mm and less than 1.30 mm, the amount of spin on shots with a middle iron increases. By forming the cover from a specific cover material, the spin rate is reduced on driver shots and increased on short iron shots. By forming the coating from a specific paint resin, the amount of spin on approach shots (particularly when the ball is biting into the turf) is improved, and the abrasion resistance and stain resistance of the golf ball surface are also improved. By controlling the amount of compressive deformation of the golf ball to 2.00 mm or more and less than 2.70 mm, the initial velocity on driver shots increases, improving distance performance. Therefore, by having the above-described configuration, the golf ball of the present invention has improved wear resistance and contamination resistance on bunker shots on the golf ball surface, and has an excellent balance of overall performance including spin performance on approach shots and middle iron shots and distance performance on driver shots. [Effects of the Invention]

[0010] According to the present invention, a golf ball can be obtained that has improved abrasion resistance and contamination resistance on bunker shots on the surface, and that has a well-balanced overall performance including spin performance on approach shots and middle iron shots and distance performance on driver shots. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an explanatory diagram of a stress-strain curve of a golf ball paint resin obtained by a tensile test. [Figure 2] 1 is a partially cutaway cross-sectional view showing a golf ball according to an embodiment of the present invention; [Figure 3] FIG. 3 is a schematic cross-sectional view illustrating measurement points for the thickness of a coating film. [Figure 4] FIG. 3 is a schematic cross-sectional view illustrating measurement points for the thickness of a coating film. DETAILED DESCRIPTION OF THE INVENTION

[0012] The golf ball of the present invention is a golf ball having a golf ball body which has a spherical core, an intermediate layer which encases the spherical core, and a cover which encases the intermediate layer, and a coating film provided on the surface of the golf ball body.

[0013] (spherical core) The golf ball body has a spherical core. The spherical core has a center hardness (H0), a hardness (H5) at a point 5.0 mm away from the center of the spherical core in the radial direction, and a hardness (H 10 ), hardness at a radial distance of 15 mm from the center of the spherical core (H 15 ) and surface hardness (Hs), in Shore C hardness, satisfy the relationships of the following formulas (1) to (3): When the hardness distribution of the spherical core satisfies the relationships of the following formulas (1) to (3), the initial velocity of the ball on driver shots increases, and the spin rate on approach shots and middle iron shots increases. -3.0≦{(H5-H0)-(H 15 -H 10 )}≦3.0 (1) -3.0≦{(H 10 -H5)-(H s -H 15 )}≦3.0 (2) 5.0≦[{(H5-H0)+(H 15 -H 10 )} / 2-{(H 10 -H5)+(Hs-H 15 )} / 2]≦10.0 (3)

[0014] The value in the formula (1) {(H5-H0)-(H 15 -H 10 )} is preferably −3.0 or more, more preferably −2.5 or more, and even more preferably −2.0 or more, and is preferably 3.0 or less, in Shore C hardness.

[0015] The value {(H 10 -H5)-(H s -H 15 )} is preferably −3.0 or more, more preferably −2.5 or more, and even more preferably −2.0 or more, in Shore C hardness, and is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less.

[0016] The value in the formula (3) [{(H5-H0)+(H 15 -H 10 )} / 2-{(H 10-H5)+(Hs-H 15 )} / 2] is preferably 5.0 or more, more preferably 5.5 or more, and even more preferably 6.0 or more in Shore C hardness, and is preferably 10.0 or less, more preferably 9.5 or less, and even more preferably 9.0 or less. 15 -H 10 )} / 2-{(H 10 -H5)+(Hs-H 15 )} / 2] of 5.0 or greater reduces the amount of spin on driver shots, and of 10.0 or less improves the durability of the golf ball against impact.

[0017] The center hardness (H0), hardness (H5), hardness (H 10 ) and hardness (H 15 ) preferably satisfies the relationship of the following formula (4) in Shore C hardness. [{(H5-H0)+(H 15 -H 10 )} / 2]≧6.0 (4)

[0018] The value in the formula (4) [{(H5-H0)+(H 15 -H 10 )} / 2] is preferably 6.0 or more, more preferably 6.5 or more, and even more preferably 7.0 or more in Shore C hardness, and is preferably 11.0 or less, more preferably 10.5 or less, and even more preferably 10.0 or less. 15 -H 10 )} / 2] is 6.0 or higher, the amount of spin on a driver shot is reduced, and if it is 11.0 or lower, the golf ball has good durability against impact.

[0019] The hardness (H5), hardness (H 10 ), hardness (H 15 ) and surface hardness (Hs) preferably satisfy the relationship of the following formula (5) in Shore C hardness: [{(H 10 -H5)+(Hs-H 15 )} / 2]≦2.0 (5)

[0020] The value [{(H 10 -H5)+(Hs-H 15 )} / 2] is preferably 0.0 or more and 2.0 or less in Shore C hardness. 10 -H5)+(Hs-H 15 )} / 2] is equal to or greater than 0.0 and equal to or less than 2.0, the initial velocity of the ball on driver shots will be faster and the amount of spin on approach shots and middle iron shots will increase.

[0021] The center hardness (H0) and the surface hardness (Hs) preferably satisfy the relationship of the following formula (6) in Shore C hardness. (Hs-H0)≧18.0 (6) The value (Hs-H0) in formula (6) is preferably 18.0 or more, and 30.0 or less, more preferably 28.0 or less, and even more preferably 26.0 or less, in Shore C hardness. If the value (Hs-H0) is 18.0 or more, the spin rate on driver shots is reduced, and if it is 30.0 or less, the impact durability of the golf ball is good.

[0022] The center hardness (H0) is preferably 57.0 or more, more preferably 57.5 or more, and even more preferably 58.0 or more, in Shore C hardness, and is preferably 70.0 or less, more preferably 68.0 or less, and even more preferably 66.0 or less. If the center hardness (H0) is 57.0 or more, the impact durability of the golf ball will be good, and if it is 70.0 or less, the spin rate on driver shots will be reduced.

[0023] The surface hardness (H S The surface hardness (H) is preferably 75.0 or more, more preferably 76.0 or more, and even more preferably 77.0 or more, in Shore C hardness, and is preferably 88.0 or less, more preferably 87.0 or less, and even more preferably 86.0 or less. S ) is 75.0 or higher, the initial velocity of the ball on a driver shot will be faster, and if it is 88.0 or lower, the golf ball will have good durability against impact.

[0024] The hardness (H0), hardness (H5), hardness (H 10 ), hardness (H 15 ) and hardness (Hs) preferably satisfy the relationship of the following formula (7): H0 <H5<H 10 <H 15 <Hs ···(7)

[0025] The hardness distribution of the spherical core can be controlled by the composition of the rubber composition for forming the spherical core and the heating conditions when molding the spherical core.

[0026] The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, even more preferably 38.0 mm or more, and is preferably 42.2 mm or less, more preferably 41.8 mm or less, even more preferably 41.2 mm or less, and most preferably 40.8 mm or less.

[0027] When the diameter of the spherical core is 34.8 mm to 42.2 mm, the amount of compressive deformation (the amount of shrinkage of the spherical core in the compressive direction) from an initial load of 98 N to a final load of 1275 N is preferably 2.50 mm or more, more preferably 2.55 mm or more, and even more preferably 2.60 mm or more, and is preferably 3.30 mm or less, more preferably 3.25 mm or less, and even more preferably 3.20 mm or less. If the amount of compressive deformation is within the above range, the shot feel will be better.

[0028] The spherical core may have either a single-layer structure or a multi-layer structure of two or more layers, but a single-layer structure is preferred. A single-layer spherical core eliminates energy loss at the interface of the multi-layer structure upon impact, improving resilience.

[0029] A known rubber composition (hereinafter, sometimes simply referred to as a "core rubber composition") can be used for the spherical core. For example, a rubber composition containing a base rubber, a co-crosslinking agent, and a crosslinking initiator can be molded by hot pressing.

[0030] The base rubber can be natural rubber and / or synthetic rubber. Examples of the base rubber that can be used include polybutadiene rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, and ethylene-propylene-diene rubber (EPDM). These may be used alone or in combination of two or more. It is particularly preferable to use high-cis polybutadiene, which has cis bonds that are advantageous for rebound, at 40% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

[0031] The co-crosslinking agent is preferably an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof, more preferably acrylic acid or a metal salt thereof, or methacrylic acid or a metal salt thereof. The metal in the metal salt is preferably zinc, magnesium, calcium, aluminum, or sodium, more preferably zinc. The amount of the co-crosslinking agent used is preferably 20 to 50 parts by weight per 100 parts by weight 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 incorporate a metal compound (e.g., magnesium oxide).

[0032] As the crosslinking initiator, an organic peroxide is preferably used. Specific examples include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide. Of these, dicumyl peroxide is preferably used. The amount of crosslinking initiator added is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more, per 100 parts by mass of base rubber; and is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less.

[0033] The core rubber composition may further contain a monophenol compound having a substituent only at the p-position. The monophenol compound having a substituent only at the p-position is a compound in which a substituent is directly bonded to the p-position relative to one hydroxy group of phenol, and has no substituents at the o- and m-positions of the hydroxy group. Examples of the substituent at the p-position include an alkoxy group, a halogen group, a hydrocarbon group, a nitro group, a cyano group, an amino group, and a hydroxy group, with an alkoxy group being preferred. An example of the monophenol compound having a substituent only at the p-position is 4-methoxyphenol. The amount of the monophenol compound having a substituent only at the p-position is preferably at least 0.05 parts by mass, more preferably at least 0.07 parts by mass, and even more preferably at least 0.10 parts by mass, per 100 parts by mass of the base rubber, and is preferably at most 2.0 parts by mass, more preferably at most 1.8 parts by mass, and even more preferably at most 1.6 parts by mass.

[0034] The core rubber composition may further contain an organic sulfur compound. Suitable organic sulfur compounds include diphenyl disulfides (such as diphenyl disulfide and bis(pentabromophenyl) disulfide), thiophenols, and thionaphthols. The amount of organic sulfur compound added is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more, and even more preferably 0.3 parts by weight or more, per 100 parts by weight of the base rubber. The amount is preferably 5.0 parts by weight or less, more preferably 4.0 parts by weight or less, and even more preferably 2.0 parts by weight or less.

[0035] The core rubber composition may further contain a carboxylic acid and / or a salt thereof. The carboxylic acid and / or a salt thereof is preferably a carboxylic acid and / or a salt thereof having 1 to 30 carbon atoms. The carboxylic acid may be either an aliphatic carboxylic acid or an aromatic carboxylic acid (such as benzoic acid). The amount of the carboxylic acid and / or a salt thereof is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the base rubber.

[0036] In addition to the base rubber, co-crosslinking agent, crosslinking initiator, and organic sulfur compound, the core rubber composition may further contain, as appropriate, a weight adjuster such as zinc oxide or barium sulfate, an antioxidant, a color powder, and the like.

[0037] The core rubber composition can be prepared by mixing and kneading the raw materials. The kneading method is not particularly limited, and may be carried out using a known kneading machine such as a kneading roll, a Banbury mixer, or a kneader.

[0038] The conditions for hot press molding the core rubber composition may be set appropriately depending on the rubber composition. Examples include a mode in which heating is performed at 150°C to 170°C for 15 to 20 minutes, and a mode in which heating is performed in two stages, namely, heating at 140°C to 150°C for 8 to 12 minutes, followed by heating at 150°C to 160°C for 10 to 15 minutes.

[0039] (middle class) The golf ball body has a mid layer that encases the spherical core. The mid layer may be one layer or two or more layers, but is preferably one layer.

[0040] The thickness of the intermediate layer is preferably 0.70 mm or more, more preferably 0.75 mm or more, and even more preferably 0.80 mm or more, and is preferably less than 1.30 mm, more preferably 1.25 mm or less, and even more preferably 1.20 mm or less. An intermediate layer thickness of 0.70 mm or more improves the productivity and durability of the golf ball upon impact, while a thickness of less than 1.30 mm increases the spin rate upon middle iron shots. When multiple intermediate layers are used, the thickness of the intermediate layer is defined as the total thickness of all intermediate layers.

[0041] Examples of resin components used in the intermediate layer composition for forming the intermediate layer include thermoplastic resins such as polyurethane resins, ionomer resins, polyamide resins, and polyethylene; and thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyurethane elastomers, polyamide elastomers, and polyester elastomers. Examples of ionomer resins include copolymers of ethylene and α,β-unsaturated carboxylic acids in which at least a portion of the carboxyl groups has been neutralized with metal ions, and terpolymers of ethylene, α,β-unsaturated carboxylic acids, and α,β-unsaturated carboxylic acid esters in which at least a portion of the carboxyl groups has been neutralized with metal ions. The intermediate layer composition may further contain weight adjusters such as barium sulfate and tungsten, antioxidants, pigments (titanium dioxide, etc.), and the like.

[0042] The intermediate layer composition constituting the intermediate layer preferably has a slab hardness of at least 60, more preferably at least 62, and even more preferably at least 63, in Shore D hardness, and preferably has a slab hardness of at most 75, more preferably at most 74, and even more preferably at most 73. If the slab hardness is at least 60, in Shore D hardness, good distance performance is achieved even with long iron shots, and if it is at most 75, good feeling is achieved when hitting.

[0043] (cover) The golf ball body has a cover that encases the mid layer, and the cover is the outermost layer of the golf ball body.

[0044] The cover has a loss modulus (E") at a measurement temperature of -40°C measured using a dynamic viscoelasticity device under the following measurement conditions. -40 ) is 6.50×10 7 Pa~22.0×10 7 Pa, and the loss modulus (E -20 ) is 3.50×10 7 Pa ~ 7.10 x 10 7 The cover is made of a Pa material.

[0045] <Measurement conditions for dynamic viscoelasticity device> Measurement mode: Tensile Measurement temperature: -100℃~100℃ Heating rate: 4°C / min Excitation frequency: 10Hz Measurement distortion: 0.05%

[0046] The loss modulus (E" -40 The loss modulus (E”) is a physical property that affects the amount of spin on a driver shot. -40 ) can reduce the amount of spin on driver shots. The loss modulus (E -40 ) is 6.50 x 10 7 Pa or more is preferable, and 6.60×10 7 Pa or more, more preferably 6.70 × 10 7 Pa or more, 22.0 × 10 7 Pa or less, and more preferably 21.0 × 10 7 Pa or less, more preferably 20.0 × 10 7 The loss modulus (E -40 ) is 6.50 x 10 7 If the ball is over 22.0 x 10 Pa, the spin rate on driver shots will be reduced. 7 If it is less than Pa, handling in the production process becomes easy.

[0047] The loss modulus (E" -20 ) is a physical property that affects the amount of spin on short iron shots. -20 By controlling the loss modulus (E”), it is possible to increase the spin rate on shots with short irons. -20 ) is 3.50 x 10 7 Pa or more is preferable, and 3.60×10 7 Pa or more, more preferably 3.70 × 10 7 Pa or greater than 7.10 x 10 7Pa or less, and more preferably 7.00 × 10 7 Pa or less, more preferably 6.90 × 10 7 The loss modulus (E -20 ) is 3.50×10 7 If the spin rate is above 7.10 x 10 Pa, the spin rate on iron shots will increase. 7 If the value is equal to or less than Pa, the decrease in the initial velocity of the ball on a driver shot is suppressed.

[0048] The slab hardness of the golf ball cover material is preferably 65 or more, more preferably 68 or more, and even more preferably 70 or more, in Shore A hardness, and is preferably 95 or less, more preferably 93 or less, and even more preferably 92 or less. If the slab hardness is 65 or more, in Shore A hardness, handling during the production process becomes easy, and if it is 95 or less, the spin rate on approach shots can be maintained high.

[0049] The golf ball cover material preferably contains, as a resin component, a polyurethane for the cover obtained by reacting a polyol with a polyisocyanate.

[0050] The polyol is a compound having two or more hydroxy groups in the molecule, and one type of the polyol may be used alone, or two or more types may be used in combination.

[0051] The polyol constituting the cover polyurethane preferably has a number-average molecular weight of 200 or more and 6000 or less. Polyols with a number-average molecular weight of 200 or more and 6000 or less form soft segments, imparting flexibility to the polyurethane. The number average molecular weight of the polyol constituting the cover polyurethane is preferably 200 or more, more preferably 300 or more, and even more preferably 1000 or more, and is preferably 6000 or less, more preferably 4000 or less, and even more preferably 3000 or less.

[0052] The polyol constituting the cover polyurethane is preferably at least one polymer polyol selected from the group consisting of polyether polyols, condensation polyester polyols, lactone polyester polyols, polycarbonate polyols, and acrylic polyols. Polymer polyols are polymers obtained by polymerizing low-molecular-weight compounds and have multiple hydroxy groups. The polymer polyol may be derived from petroleum resources or biomass resources.

[0053] Examples of the polyether polyol include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), polytrimethylene ether glycol (PO3G), and polytetramethylene ether glycol (PTMG). Examples of the condensation polyester polyol include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). Examples of the lactone-based polyester polyol include poly-ε-caprolactone (PCL). The polycarbonate polyol may, for example, be polyhexamethylene carbonate.

[0054] The polymer polyol is preferably a polymer diol having two hydroxy groups. Use of a polymer diol results in a linear thermoplastic polyurethane, which can be easily molded into components constituting a golf ball.

[0055] The polyol constituting the cover polyurethane is preferably a polyether polyol. In particular, the content of the polyether polyol in 100% by mass of the polyol constituting the polyurethane is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. A polyether polyol content of 50% by mass or more allows mechanical strength to be maintained for a long period of time. When the golf ball cover material contains two or more types of cover polyurethanes, the content of the polyether polyol in 100% by mass of the polyol constituting each polyurethane is preferably within the above-mentioned range.

[0056] The polyol constituting the polyurethane for the cover preferably contains a first polymer polyol and a second polymer polyol having a number average molecular weight greater than that of the first polymer polyol. By containing the first polymer polyol and the second polymer polyol, the spin rate on iron shots can be further increased. Examples of embodiments in which the polyol constituting the cover polyurethane contains a first polymer polyol and a second polymer polyol include an embodiment in which the first polymer polyol and the second polymer polyol are contained as polyols constituting one type of polyurethane; and an embodiment in which a first polyurethane containing the first polymer polyol as a polyol constituting a component is used in combination with a second polyurethane containing the second polymer polyol as a polyol constituting a component.

[0057] When the polyol constituting the cover polyurethane contains a first polymer polyol and a second polymer polyol, the difference (Mm2-Mm1) between the number average molecular weight (Mm1) of the first polymer polyol and the number average molecular weight (Mm2) of the second polymer polyol is preferably 50 or more, more preferably 100 or more, and even more preferably 200 or more, and is preferably 1500 or less, more preferably 1200 or less, and even more preferably 1000 or less.

[0058] The number average molecular weight (Mm1) of the first polymer polyol is preferably 200 or more, more preferably 500 or more, and even more preferably 800 or more, and is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1500 or less. The number average molecular weight (Mm2) of the second polymer polyol is preferably 1,000 or more, more preferably 1,200 or more, and even more preferably 1,400 or more, and is preferably 6,000 or less, more preferably 4,500 or less, and even more preferably 3,000 or less.

[0059] The polyisocyanate constituting the cover polyurethane is not particularly limited as long as it has two or more isocyanate groups. The polyisocyanates may be used alone or in combination of two or more. Examples of the polyisocyanate include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. Examples of aromatic polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI). Alicyclic or aliphatic polyisocyanates include 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of suitable isocyanates include hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI).

[0060] From the viewpoint of improving abrasion resistance, it is preferable to use an aromatic polyisocyanate as the polyisocyanate constituting the polyurethane for the cover, since the use of an aromatic polyisocyanate improves the mechanical properties of the resulting polyurethane, resulting in a cover with excellent abrasion resistance. In addition, from the viewpoint of improving weather resistance, non-yellowing polyisocyanates (TMXDI, XDI, HDI, H6XDI, IPDI, H) are used as polyisocyanates that make up polyurethane. 12 It is preferable to use 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI) is used. 4,4'-Dicyclohexylmethane diisocyanate (H 12 MDI) has a rigid structure, which improves the weather resistance and mechanical properties of the resulting polyurethane, resulting in a cover with excellent abrasion resistance.

[0061] The polyurethane for the cover may contain a chain extender as a constituent component, provided that the effect of the present invention is not impaired. Examples of the chain extender component include low-molecular-weight polyols and low-molecular-weight polyamines. Examples of low molecular weight polyols include diols such as ethylene glycol, diethylene glycol, triethylene glycol, propanediols (e.g., 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol), dipropylene glycol, butanediols (e.g., 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,3-dimethyl-2,3-butanediol), neopentyl glycol, pentanediol, hexanediol, heptanediol, octanediol, and 1,4-cyclohexanedimethylol; triols such as glycerin, trimethylolpropane, and hexanetriol; and tetraols or hexaols such as pentaerythritol and sorbitol.

[0062] The low molecular weight polyamine that can be used as the chain extender component is not particularly limited as long as it has at least two amino groups. Examples of the polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, and hexamethylenediamine; alicyclic polyamines such as isophoronediamine and piperazine; and aromatic polyamines.

[0063] The aromatic polyamine is not particularly limited as long as it has at least two amino groups directly or indirectly bonded to an aromatic ring, where "indirectly bonded" means that the amino groups are bonded to the aromatic ring via, for example, a lower alkylene group. The aromatic polyamine may be, for example, a monocyclic aromatic polyamine in which two or more amino groups are bonded to one aromatic ring, or a polycyclic aromatic polyamine containing two or more aminophenyl groups in which at least one amino group is bonded to one aromatic ring.

[0064] Examples of the monocyclic aromatic polyamine include phenylenediamine, toluenediamine, diethyltoluenediamine, dimethylthiotoluenediamine, and the like, in which an amino group is directly bonded to an aromatic ring; and xylylenediamine, in which an amino group is bonded to an aromatic ring via a lower alkylene group. The polycyclic aromatic polyamine may be a poly(aminobenzene) in which at least two aminophenyl groups are directly bonded, or may be a poly(aminobenzene) in which at least two aminophenyl groups are bonded via a lower alkylene group or an alkylene oxide group. Among these, diaminodiphenylalkanes in which two aminophenyl groups are bonded via a lower alkylene group are preferred, and 4,4'-diaminodiphenylmethane and its derivatives are particularly preferred.

[0065] The molecular weight of the chain extender is preferably 400 or less, more preferably 350 or less, even more preferably less than 200, and preferably 30 or more, more preferably 40 or more, and even more preferably 45 or more. Note that the "low molecular weight polyols" and "low molecular weight polyamines" used as chain extenders are low molecular weight compounds that do not have a molecular weight distribution, and are therefore distinguished from polymer polyols that are obtained by polymerizing low molecular weight compounds and have a number average molecular weight of 200 to 3,000.

[0066] The configuration of the polyurethane for the cover is not particularly limited, but examples include a configuration composed of a polyisocyanate and a polyol having a number average molecular weight of 200 or more and 6000 or less; a configuration composed of a polyisocyanate, a polyol having a number average molecular weight of 200 or more and 6000 or less, and a chain extender; and a configuration composed of a polyisocyanate, a first polymer polyol having a number average molecular weight of 200 or more and 3000 or less, a second polymer polyol having a number average molecular weight of 1000 or more and 6000 or less and having a higher number average molecular weight than the first polymer polyol, and a chain extender component.

[0067] The polyurethane for the cover can be either a thermoplastic polyurethane or a thermosetting polyurethane. Thermoplastic polyurethane is a polyurethane that exhibits plasticity upon heating, and generally refers to a polyurethane with a linear structure that has a certain degree of high molecular weight. Thermosetting polyurethane is a polyurethane obtained by a curing reaction between a relatively low molecular weight prepolymer and a curing agent. Thermosetting polyurethane forms a three-dimensional crosslinked structure by controlling the number of functional groups in the prepolymer and curing agent used. The polyurethane is preferably a thermoplastic polyurethane. Thermoplastic polyurethane facilitates moldability of the cover.

[0068] The polyurethane for the cover can be synthesized by a one-shot method or a prepolymer method. The one-shot method is a method in which polyisocyanate, polyol, etc. are reacted all at once. The prepolymer method is a method in which polyisocyanate, polyol, etc. are reacted in multiple stages, for example, by synthesizing a relatively low-molecular-weight urethane prepolymer and then subsequently increasing the molecular weight.

[0069] As an example of a method for producing polyurethane by the prepolymer method, a method in which an isocyanate group-terminated urethane prepolymer is synthesized and then polymerized with a chain extender will be described in detail below.

[0070] First, polyisocyanate and polymer polyol are reacted to synthesize an isocyanate-terminated urethane prepolymer. In this case, the molar ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanate to the hydroxyl groups (OH) of the polymer polyol is preferably 1.0 or more, more preferably 1.2 or more, and even more preferably 1.5 or more, and is preferably 10 or less, more preferably 9 or less, and even more preferably 8 or less.

[0071] The temperature during the prepolymerization reaction is preferably 10°C or higher, more preferably 30°C or higher, and even more preferably 50°C or higher, and is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower. The reaction time is preferably 10 minutes or longer, more preferably 1 hour or longer, and even more preferably 3 hours or longer, and is preferably 32 hours or shorter, more preferably 16 hours or shorter, and even more preferably 8 hours or shorter.

[0072] The resulting isocyanate-terminated urethane prepolymer is then subjected to a chain extension reaction with a chain extender to obtain a high-molecular-weight polyurethane. The molar ratio (NCO / OH) of the isocyanate groups (NCO) in the isocyanate-terminated urethane prepolymer to the hydroxyl groups (OH) in the chain extender is preferably 0.9 or more, more preferably 0.92 or more, and even more preferably 0.95 or more, and is preferably 1.1 or less, more preferably 1.08 or less, and even more preferably 1.05 or less.

[0073] The temperature at which the chain extension reaction is carried out is preferably 10°C or higher, more preferably 30°C or higher, and even more preferably 50°C or higher, and is preferably 220°C or lower, more preferably 170°C or lower, and even more preferably 120°C or lower. The reaction time is preferably 10 minutes or more, more preferably 30 minutes or more, and even more preferably 1 hour or more, and is preferably 20 days or less, more preferably 10 days or less, and even more preferably 5 days or less.

[0074] Both the prepolymerization reaction and the chain extension reaction are preferably carried out in a dry nitrogen atmosphere.

[0075] Known catalysts can be used in synthesizing the polyurethane for the cover. Examples of such catalysts include monoamines such as triethylamine and N,N-dimethylcyclohexylamine; polyamines such as N,N,N',N'-tetramethylethylenediamine and N,N,N',N",N"-pentamethyldiethylenetriamine; cyclic diamines such as 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) and triethylenediamine; and tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate. These catalysts may be used alone or in combination of two or more. Among these, tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate are preferred, with dibutyltin dilaurate being particularly preferred.

[0076] The content of the polyurethane for the cover in 100% by mass of the resin components of the golf ball cover material is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. The resin components may contain only the polyurethane for the cover.

[0077] The golf ball cover material may contain one type of cover polyurethane or two or more types of cover polyurethane as a resin component. The golf ball cover material preferably contains a first cover polyurethane containing a first polymer polyol as a constituent component and a second cover polyurethane containing a second polymer polyol as a constituent component.

[0078] When the golf ball cover material contains a first cover polyurethane and a second cover polyurethane as resin components, the mass ratio thereof (first cover polyurethane / second cover polyurethane) is preferably 1 / 99 or more, more preferably 30 / 70 or more, and even more preferably 50 / 50 or more, and is preferably 99 / 1 or less, more preferably 98 / 2 or less, and even more preferably 95 / 5 or less.

[0079] The golf ball cover material preferably contains only polyurethane for the cover as the resin component, but may contain other resin components as long as the effects of the present invention are not impaired.

[0080] Examples of the other resin components include ionomer resins and thermoplastic elastomers. Examples of the ionomer resin include a copolymer of ethylene and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, in which at least a portion of the carboxyl groups have been neutralized with metal ions, a terpolymer of ethylene, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester, in which at least a portion of the carboxyl groups have been neutralized with metal ions, and a mixture thereof. Specific examples of the ionomer resin include "Himilan (registered trademark)" manufactured by Mitsui Dow Polychemical, "Surlyn (registered trademark)" manufactured by DuPont, and "Iotek (registered trademark)" manufactured by ExxonMobil Chemical. Specific examples of the thermoplastic elastomer include thermoplastic polyurethane elastomers such as "Elastollan (registered trademark)" (e.g., "Elastollan XNY88A") manufactured by BASF Japan; thermoplastic polyamide elastomers such as "Pebax (registered trademark)" manufactured by Arkema (e.g., "Pebax 2533"); thermoplastic polyester elastomers such as "Hytrel (registered trademark)" manufactured by Toray DuPont (e.g., "Hytrel 3548" and "Hytrel 4047"); and thermoplastic polystyrene elastomers such as "Tefabloc (registered trademark)" manufactured by Mitsubishi Chemical Corporation.

[0081] The golf ball cover material may further contain pigment components such as titanium oxide and blue pigments, weight adjusters such as calcium carbonate and barium sulfate, dispersants, antioxidants, ultraviolet absorbers, light stabilizers, fluorescent materials, or fluorescent brighteners, to the extent that the cover performance is not impaired.

[0082] The amount of the white pigment (titanium oxide) is preferably at least 0.5 parts by weight, more preferably at least 1 part by weight, and even more preferably at least 1.5 parts by weight, and is preferably at most 10 parts by weight, more preferably at most 8 parts by weight, and even more preferably at most 6 parts by weight, per 100 parts by weight of the resin component. A white pigment amount of 0.5 parts by weight or more can impart hiding properties to the golf ball material, while a white pigment amount of 10 parts by weight or less can prevent a decrease in the durability of the golf ball material.

[0083] The manner in which the cover is molded using the cover material is not particularly limited, but examples include a manner in which the cover material is directly injection molded onto the spherical core, or a manner in which a hollow shell is molded from the cover material, the spherical core is covered with multiple shells, and then compression molded (preferably a method in which a hollow half shell is molded from the cover material, the spherical core is covered with two half shells, and then compression molded). The golf ball body with the molded cover is preferably removed from the mold and, as necessary, subjected to surface treatment such as deburring, cleaning, and sandblasting. Marks can also be formed, if desired.

[0084] The cover thickness is preferably 0.3 mm or more, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.0 mm or less. A cover thickness of 0.3 mm or more makes it easier to mold the cover, while a cover thickness of 2.0 mm or less allows the core diameter to be relatively large, improving the resilience performance of the golf ball.

[0085] The total number of dimples formed on the cover is preferably 200 to 500. If the total number of dimples is less than 200, the effect of the dimples is difficult to obtain. If the total number of dimples is more than 500, the size of each dimple becomes small, making it difficult to obtain the effect of the dimples. The shape (shape in plan view) of the dimples formed is not particularly limited, and the following may be used alone or in combination: circle; polygon such as approximately triangle, approximately square, approximately pentagon, approximately hexagon; or other irregular shape.

[0086] (paint film) The golf ball has a coating film provided on the surface of the golf ball body. In a tensile test, the coating film is deformed until the strain reaches a predetermined value εmax, and then the stress is reduced to 0 kgf / cm 2 The deformation is reduced until the stress at 10% strain is M10 (kgf / cm 2) and the stress when the deformation is reduced is 0 kgf / cm 2 When the strain at this time is ε1 (%), the material is made of a paint resin that satisfies the relationship 0.10≦ε1 / M10≦1.00.

[0087] <Test conditions for tensile test> Test piece dimensions: width 4 mm, thickness 100 μm ± 10 μm Chuck distance: 20mm Measurement temperature: 23℃ Deformation increasing tensile speed: 1.1 mm / sec Deformation reduction return speed: 1.1 mm / sec Load data acquisition points per second: 50 Distortion setting value: 10 mm (εmax = 50%)

[0088] By using a resin for the coating that satisfies the above-mentioned specific conditions in the stress-strain curve obtained by a tensile test, the spin performance of the golf ball on approach shots (particularly on approach shots from the rough) is improved, and the ball surface has excellent abrasion resistance and contamination resistance from bunker shots. The reasons for the improved spin performance on approach shots and the excellent abrasion resistance and contamination resistance from bunker shots are not clear, but it is thought that the coating film on the golf ball of the present invention has a strong ability to return to its original shape even when deformed during bunker shots, making it difficult for sand, soil, grass juice, and other contaminants to penetrate, and even if the surface does become contaminated, the contaminants are easy to remove.

[0089] The tensile test method for the golf ball paint resin will be explained below.

[0090] A strip-shaped test piece for a tensile test is prepared having dimensions of 4 mm in width, 20 mm or more in length, and 100 μm±10 μm in thickness. The length of the test piece is not particularly limited as long as it is long enough to achieve a chuck distance of 20 mm during the tensile test, and is preferably 25 mm or more and 35 mm or less.

[0091] The tensile tester is not particularly limited, but it is preferable to use a dynamic viscoelasticity measuring device, such as Rheogel-E4000 manufactured by UBM.

[0092] The tensile test is carried out according to the following procedure. 1) The rectangular test piece is gripped with a chuck and moved in the direction of increasing deformation until the strain of the test piece reaches the specified value εmax. The distance between the chucks is 20 mm. The tensile speed during increasing deformation is 1.1 mm / sec. The stress M10 (kgf / cm) when the strain of the test piece during increasing deformation is 10% is 2 ) and the stress M50 (kgf / cm at a given value of εmax (εmax=50%) 2 ) are recorded respectively. 2) After the strain reaches the specified value εmax, the chuck is immediately returned in the direction that reduces the deformation of the test piece. The deformation reduction return speed is 1.1 mm / sec. 3) Record the strain ε1 when the stress on the test piece becomes zero. 4) The temperature for the tensile test was 23°C, and the number of data acquisition points per second was 50.

[0093] FIG. 1 is a schematic diagram of an example of a stress-strain curve during a tensile test according to the present invention. Curve a is a stress-strain curve obtained when the chuck is moved in the direction that increases the deformation of the test specimen and the test specimen is pulled until the strain reaches a predetermined value εmax (during deformation increase). In the present invention, the stress at 10% strain in curve a is defined as M10, and the stress at the predetermined value εmax (εmax = 50%) is defined as M50. Curve b is a stress-strain curve obtained when the chuck is moved in the direction that decreases the deformation of the test specimen after the strain reaches the predetermined value εmax (during deformation decrease). The stress applied to the sample is zero at the intersection of curve b and the X-axis. In the present invention, the strain at this intersection is defined as ε1. Note that although FIG. 1 shows ε1 > 10%, it is also possible for ε1 = 10% or ε1 < 10%.

[0094] In the present invention, the strain ε is expressed as strain ε (%)=100×ΔL / L, where L is the distance between the chucks of the test piece before loading and ΔL is the displacement upon deformation.

[0095] In the tensile test of the present invention, the test piece is pulled in the direction that increases the deformation until the strain of the test piece reaches a predetermined value εmax = 50%, and after the strain reaches the predetermined value εmax = 50%, the chuck is returned in the direction that decreases the deformation.

[0096] In the tensile test, the test piece of the golf ball paint resin is deformed until the strain reaches a predetermined value εmax=50%, and then the stress is increased to 0 kgf / cm 2 The deformation is reduced until the stress at 10% strain is M10 (kgf / cm 2 ) and the stress when the deformation is reduced is 0 kgf / cm 2 When the strain at this time is ε1 (%), it is preferable that the relationship of 0.10≦ε1 / M10≦1.00 is satisfied. ε1 / M10 is preferably 0.20 or more, more preferably 0.40 or more, and is preferably 0.95 or less, more preferably 0.90 or less.

[0097] The golf ball paint resin is a resin having a stress of 0 kgf / cm in the tensile test. 2 The strain value (ε1) at the time of reaching this point is preferably 40% or less, more preferably 38% or less, and even more preferably 36% or less. The strain value (ε1) is not particularly limited, but is preferably 0% or more, and more preferably 1% or more.

[0098] In the tensile test, the stress M10 (also called "10% modulus") at 10% strain of the golf ball paint resin is 5 kgf / cm 2 (0.49 MPa) or more is preferable, and 10 kgf / cm is more preferable. 2 (0.98 MPa) or more, more preferably 15 kgf / cm 2 (1.47MPa) or more, 100kgf / cm 2(9.80 MPa) or less is preferable, and 95 kgf / cm 2 (9.31 MPa) or less, more preferably 90 kgf / cm 2 (8.82 MPa) or less. The stress M10 is 5 kgf / cm 2 More than 100kgf / cm 2 If the value is below this, the feel when hitting with the putter will be good.

[0099] In the tensile test, the stress M50 (also called "50% modulus") of the golf ball paint resin when the strain is a predetermined value εmax (εmax=50%) is 10 kgf / cm 2 More preferably, 20 kgf / cm 2 More preferably, 30 kgf / cm 2 or more, 150kgf / cm 2 Preferably less than 140 kgf / cm 2 or less, more preferably 130 kgf / cm 2 If the stress M50 is within the above range, the feel when hitting with a putter will be good.

[0100] The tensile properties of the resin for golf ball paint can be controlled by, for example, the constituent components and the amounts of the components.

[0101] The golf ball paint resin preferably contains a paint polyurethane as a resin component. The content of the paint polyurethane in the resin component is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. In another preferred embodiment, the resin component of the paint consists essentially of paint polyurethane alone.

[0102] The paint polyurethane is a polymer having multiple urethane bonds in its main chain. The paint polyurethane is preferably obtained by reacting a polyisocyanate composition containing a polyisocyanate with a polyol composition containing a polyol. The reaction between the polyisocyanate and the polyol forms multiple urethane bonds in the main chain of the polyurethane. The resulting paint polyurethane has a polyisocyanate component derived from the polyisocyanate and a polyol component derived from the polyol.

[0103] The polyol component constituting the polyurethane for paint contains, for example, a low molecular weight polyol having a molecular weight of less than 400 and a high molecular weight polyol having a number average molecular weight of 400 or more.

[0104] Examples of the high molecular weight polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, and acrylic polyols. Examples of the polyether polyols include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG). Examples of the polyester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). Examples of the polycaprolactone polyols include poly-ε-caprolactone (PCL). Examples of the polycarbonate polyols include polyhexamethylene carbonate. The high molecular weight polyols may be used alone or in combination of two or more.

[0105] Examples of the low molecular weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol, and triols such as glycerin, trimethylolpropane, and hexanetriol. The low molecular weight polyols may be used alone or in combination of two or more.

[0106] The polyurethane for paint contained in the resin for paint preferably contains at least one polyol component selected from the group consisting of polyether diol, polyester diol, polycaprolactone diol, and polycarbonate diol, and more preferably contains polycarbonate diol as the polyol component.

[0107] The polycarbonate diol is preferably a liquid polycarbonate diol. Here, "liquid" means a viscous liquid at 25° C. By using a liquid polycarbonate diol, the coating film becomes softer and the feel when hitting with a putter becomes good.

[0108] The number average molecular weight of the polycarbonate diol is preferably 400 or more, more preferably 450 or more, even more preferably 500 or more, and preferably 1200 or less, more preferably 1100 or less, and even more preferably 1000 or less. If the number average molecular weight of the polycarbonate diol is 400 or more and 1200 or less, the distance between crosslinking points in the coating film is appropriate, resulting in a good putter feel. The number average molecular weight of the polyol can be measured, for example, by gel permeation chromatography (GPC) using polystyrene as a standard, tetrahydrofuran as an eluent, and an organic solvent-based GPC column (for example, "Shodex (registered trademark) KF series" manufactured by Showa Denko K.K.).

[0109] The polyisocyanate component constituting the polyurethane contained in the golf ball paint resin can be, for example, a compound having at least two isocyanate groups. Examples of the polyisocyanate include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of the polyisocyanate include alicyclic polyisocyanates or aliphatic polyisocyanates such as methyl methyl diisocyanate (MDI), hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI); and derivatives of these polyisocyanates. In the present invention, two or more types of polyisocyanates may be used as the polyisocyanate.

[0110] Examples of the polyisocyanate derivatives include adduct-modified products obtained by reacting diisocyanate with polyhydric alcohol, isocyanurate-modified products of diisocyanate, biuret-modified products, and allophanate-modified products, and those from which free diisocyanate has been removed are more preferred.The polyisocyanate composition preferably contains, as a polyisocyanate component, at least one selected from the group consisting of an isocyanurate-modified product of hexamethylene diisocyanate, an adduct-modified product of hexamethylene diisocyanate, a biuret-modified product of hexamethylene diisocyanate, and an isocyanurate-modified product of isophorone diisocyanate.

[0111] An example of the biuret modified product is a biuret modified product (formula (1) below) obtained by trimerizing a diisocyanate. In formula (1), R represents a residue obtained by removing an isocyanate group from a diisocyanate. The biuret modified product is preferably a trimer of hexamethylene diisocyanate.

[0112] [ka]

[0113] An example of the isocyanurate-modified product is a diisocyanate trimer represented by the following formula (2): In formula (2), R represents a residue obtained by removing an isocyanate group from a diisocyanate. Examples of the isocyanurate-modified product include an isocyanurate-modified product of hexamethylene diisocyanate or an isocyanurate-modified product of isophorone diisocyanate, and a trimer of hexamethylene diisocyanate or an isocyanurate trimer of isophorone diisocyanate is preferred.

[0114] [ka]

[0115] The adduct-modified product is a polyisocyanate obtained by reacting a diisocyanate with a polyhydric alcohol. The polyhydric alcohol is preferably a low-molecular-weight triol such as trimethylolpropane or glycerin. Preferred examples of the adduct-modified product include a triisocyanate (represented by the following formula (3)) obtained by reacting a diisocyanate with trimethylolpropane, and a triisocyanate (represented by the following formula (4)) obtained by reacting a diisocyanate with glycerin. In formulas (3) and (4), R represents a residue obtained by removing an isocyanate group from a diisocyanate.

[0116] [ka]

[0117] As the adduct modified product, for example, an adduct modified product of hexamethylene diisocyanate is preferred, and a triisocyanate obtained by reacting hexamethylene diisocyanate with trimethylolpropane; or a triisocyanate obtained by reacting hexamethylene diisocyanate with glycerin is preferred.

[0118] The allophanate is, for example, a triisocyanate obtained by reacting a diisocyanate with a low molecular weight diol to form a urethane bond, and then further reacting the urethane bond with a diisocyanate.

[0119] (adduct modification) In a preferred embodiment, the polyisocyanate component is preferably an adduct-modified product, and more preferably an adduct-modified product of hexamethylene diisocyanate (preferably a trimer). When an adduct-modified product of hexamethylene diisocyanate is used, the content of the adduct-modified product of hexamethylene diisocyanate in the polyisocyanate component is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The adduct-modified product of hexamethylene diisocyanate may be used alone as the polyisocyanate component.

[0120] (Isocyanurate modified substance) In another preferred embodiment, the polyisocyanate component is preferably an isocyanurate-modified product, more preferably an isocyanurate-modified product of hexamethylene diisocyanate (preferably a trimer) or an isocyanurate-modified product of isophorone diisocyanate (preferably a trimer). An isocyanurate-modified product of hexamethylene diisocyanate (preferably a trimer) and an isocyanurate-modified product of isophorone diisocyanate (preferably a trimer) may be used in combination. When used in combination, the mass ratio of the isocyanurate-modified product of hexamethylene diisocyanate to the isocyanurate-modified product of isophorone diisocyanate (isocyanurate-modified product of hexamethylene diisocyanate / isocyanurate-modified product of isophorone diisocyanate) is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and preferably 9 or less, more preferably 4 or less, even more preferably 3 or less.

[0121] (Adduct modified + Isocyanurate modified) In another preferred embodiment, the polyisocyanate component preferably uses an adduct-modified product and an isocyanurate-modified product in combination, and more preferably uses an adduct-modified product (preferably a trimer) of hexamethylene diisocyanate and an isocyanurate-modified product (preferably a trimer) of hexamethylene diisocyanate in combination, or an adduct-modified product (preferably a trimer) of hexamethylene diisocyanate and an isocyanurate-modified product (preferably a trimer) of isophorone diisocyanate in combination. In this case, the mass ratio of the adduct-modified product to the isocyanurate-modified product (adduct-modified product / isocyanurate-modified product) is preferably 0.1 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 9 or less, more preferably 5 or less, even more preferably 4 or less.

[0122] (HDI adduct modified + HDI isocyanurate modified) In another preferred embodiment, when an adduct-modified product of hexamethylene diisocyanate and an isocyanurate-modified product of hexamethylene diisocyanate are used as the polyisocyanate component, the total content of the adduct-modified product of hexamethylene diisocyanate and the isocyanurate-modified product of hexamethylene diisocyanate in the polyisocyanate component is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable to use only the adduct-modified product of hexamethylene diisocyanate and the isocyanurate-modified product of hexamethylene diisocyanate as the polyisocyanate component.

[0123] (HDI isocyanurate modified + IPDI isocyanurate modified) In another preferred embodiment, when an isocyanurate-modified hexamethylene diisocyanate and an isocyanurate-modified isophorone diisocyanate are used as the polyisocyanate component, the total content of the isocyanurate-modified hexamethylene diisocyanate and the isocyanurate-modified isophorone diisocyanate in the polyisocyanate component is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable to use only the isocyanurate-modified hexamethylene diisocyanate and the isocyanurate-modified isophorone diisocyanate as the polyisocyanate component.

[0124] (HDI adduct modified + IPDI isocyanurate modified) In another preferred embodiment, when an adduct-modified hexamethylene diisocyanate and an isocyanurate-modified isophorone diisocyanate are used as the polyisocyanate component, the total content of the adduct-modified hexamethylene diisocyanate and the isocyanurate-modified isophorone diisocyanate in the polyisocyanate component is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable to use only the adduct-modified hexamethylene diisocyanate and the isocyanurate-modified isophorone diisocyanate as the polyisocyanate component.

[0125] The amount of isocyanate groups (NCO%) in the polyisocyanate component is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. The amount of isocyanate groups (NCO%) in the polyisocyanate component can be expressed as 100 × [number of moles of isocyanate groups in polyisocyanate × 42 (molecular weight of NCO)] / total mass (g) of polyisocyanate.

[0126] Specific examples of the polyisocyanate component include Burnock (registered trademark) D-800, Burnock DN-950, and Burnock DN-955 manufactured by DIC Corporation; Desmodur (registered trademark) N75MPA / X, Desmodur N3300, Desmodur N3390, and Desmodur L75(C), manufactured by Sumika Covestro Urethane Co., Ltd.; Coronate (registered trademark) HX, Coronate HK, Coronate HL, and Coronate EH manufactured by Tosoh Corporation; Duranate (registered trademark) 24A-100, Duranate 21S-75E, Duranate TPA-100, Duranate TKA-100, Duranate 24A-90CX, and Duranate E402-80B manufactured by Asahi Kasei Chemicals Corporation; and VESTANAT (registered trademark) T1890 manufactured by Degussa.

[0127] The golf ball paint resin is preferably formed from a paint containing a polyol composition containing a polyol component and a polyisocyanate composition containing a polyisocyanate component. An example of the paint is a so-called curing paint, which uses a polyol composition as a base and a polyisocyanate composition as a curing agent. The raw materials for forming the polyurethane paint are described below.

[0128] (Polyol composition) The polyol composition preferably contains a urethane polyol as a polyol component. The urethane polyol is a compound having a plurality of urethane bonds in the molecule and two or more hydroxy groups in one molecule. Examples of the urethane polyol include a urethane prepolymer obtained by reacting a first polyol component with a first polyisocyanate component under conditions such that the hydroxy groups of the first polyol component are in excess relative to the isocyanate groups of the first polyisocyanate component.

[0129] The polyol composition preferably contains a urethane polyol as a polyol component, and the urethane polyol preferably has a polycarbonate diol as a first polyol component. As the polycarbonate diol, those exemplified as the polycarbonate diol component constituting the polyurethane for paint can be suitably used.

[0130] The urethane polyol preferably contains, as a first polyol component, a component derived from a low-molecular-weight polyol having a molecular weight of less than 400 or a high-molecular-weight polyol having a number-average molecular weight of 400 or more, in addition to the polycarbonate diol.

[0131] Examples of the low molecular weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol, and triols such as glycerin, trimethylolpropane, and hexanetriol. The low molecular weight polyols may be used alone or in combination of two or more.

[0132] Examples of the high molecular weight polyols include polyether polyols, polyester polyols, polycaprolactone polyols, and acrylic polyols. Examples of the polyether polyols include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG). Examples of the polyester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). Examples of the polycaprolactone polyols include poly-ε-caprolactone (PCL). The high molecular weight polyols may be used alone or in combination of two or more.

[0133] The content of polycarbonate diol in the urethane polyol is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. The content of polycarbonate diol in the urethane polyol is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. The content of polycarbonate diol in the urethane polyol can be calculated from the charging ratio of the first polyol component and the first polyisocyanate component that form the urethane polyol.

[0134] The urethane polyol preferably contains a triol component and a diol component as a first polyol component. The triol component is preferably trimethylolpropane. The mixing ratio of the triol component to the diol component (triol component / diol component) is preferably 1.0 or more, more preferably 1.2 or more, and is preferably 2.6 or less, more preferably 2.4 or less, in molar ratio.

[0135] The first polyisocyanate component that can constitute the urethane polyol is not particularly limited as long as it has two or more isocyanate groups, and examples thereof include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of suitable polyisocyanates include alicyclic polyisocyanates or aliphatic polyisocyanates such as methyl methyl ether (MDI), hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI). These polyisocyanates may be used alone or in combination of two or more.

[0136] The urethane polyol preferably contains an alicyclic diisocyanate as a first polyisocyanate component.

[0137] The urethane polyol preferably has a weight-average molecular weight of 5,000 or more, more preferably 5,300 or more, and even more preferably 5,500 or more, and preferably has a weight-average molecular weight of 20,000 or less, more preferably 18,000 or less, and even more preferably 16,000 or less. If the weight-average molecular weight of the urethane polyol is 5,000 or more and 20,000 or less, the feel of hitting with a putter will be good.

[0138] The hydroxyl value of the urethane polyol is preferably 10 mgKOH / g or more, more preferably 15 mgKOH / g or more, and even more preferably 20 mgKOH / g or more, and is preferably 200 mgKOH / g or less, more preferably 190 mgKOH / g or less, and even more preferably 180 mgKOH / g or less. The hydroxyl value can be measured, for example, by the acetylation method in accordance with JIS K 1557-1.

[0139] In a preferred embodiment, the polyol composition contains only a urethane polyol as the polyol component.

[0140] The content of the urethane polyol in the polyol component contained in the polyol composition is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable to use only urethane polyol as the polyol component contained in the polyol composition.

[0141] (Polyisocyanate composition) The polyisocyanate component of the polyisocyanate composition used in the present invention can be any of the polyisocyanates exemplified as those capable of forming polyurethane. Examples of the polyisocyanate include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of suitable polyisocyanates include alicyclic or aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI); and derivatives of these polyisocyanates. The polyisocyanate composition preferably contains hexamethylene diisocyanate as a polyisocyanate component. In the present invention, two or more types of polyisocyanates may be used as the polyisocyanate.

[0142] Examples of the polyisocyanate derivatives include adduct-modified products obtained by reacting diisocyanate with polyhydric alcohols; isocyanurate-modified products of diisocyanates; biuret-modified products; and allophanate-modified products, with those from which free diisocyanates have been removed being more preferred. The polyisocyanate composition preferably contains, as a polyisocyanate component, at least one selected from the group consisting of an isocyanurate-modified product of hexamethylene diisocyanate, an adduct-modified product of hexamethylene diisocyanate, a biuret-modified product of hexamethylene diisocyanate, and an isocyanurate-modified product of isophorone diisocyanate. The polyisocyanate composition more preferably contains, as a polyisocyanate component, an isocyanurate-modified product of hexamethylene diisocyanate and an adduct-modified product of hexamethylene diisocyanate.

[0143] In the curing reaction of the curable coating composition, the molar ratio (NCO group / OH group) of the hydroxy group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition is preferably 0.6 or more, more preferably 0.75 or more, and even more preferably 0.9 or more. When the molar ratio (NCO group / OH group) is 0.6 or more, the curing reaction is favorable. The molar ratio (NCO group / OH group) is preferably 1.4 or less, more preferably 1.3 or less, and even more preferably 1.2 or less. When the molar ratio (NCO group / OH group) is 1.4 or less, the amount of isocyanate groups is not excessive, and the resulting coating film has appropriate hardness and a good appearance.

[0144] The coating material may be either a water-based coating material using water as the main dispersion medium or a solvent-based coating material using an organic solvent as the dispersion medium, but solvent-based coating materials are preferred. In the case of solvent-based coating materials, preferred solvents include toluene, isopropyl alcohol, xylene, methyl ethyl ketone, methyl ethyl isobutyl ketone, ethylene glycol monomethyl ether, ethylbenzene, propylene glycol monomethyl ether, isobutyl alcohol, and ethyl acetate. The solvent may be blended into either the polyol composition or the polyisocyanate composition, but from the viewpoint of uniformly carrying out the curing reaction, it is preferred to blend the solvent into both the polyol composition and the polyisocyanate composition.

[0145] A known catalyst can be used for the curing reaction. Examples of the catalyst include monoamines such as triethylamine and N,N-dimethylcyclohexylamine; polyamines such as N,N,N',N'-tetramethylethylenediamine and N,N,N',N'',N''-pentamethyldiethylenetriamine; cyclic diamines such as 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) and triethylenediamine; and tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate. These catalysts may be used alone or in combination of two or more. Among these, tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate are preferred, with dibutyltin dilaurate being particularly preferred.

[0146] The paint may further contain, as necessary, additives that may be generally contained in paints for golf balls, such as ultraviolet absorbers, antioxidants, light stabilizers, fluorescent brighteners, anti-blocking agents, leveling agents, slip agents, and viscosity modifiers.

[0147] The golf ball of the present invention has a golf ball body and at least one coating film formed on the surface of the golf ball body, and at least the outermost layer of the coating film is formed from the golf ball paint resin of the present invention.

[0148] When the coating film has a multi-layer structure, the coating film layer located on the outermost side is the outermost coating film layer. When the coating film has a single layer, the single layer coating film is the outermost coating film layer.

[0149] When the coating film has a multilayer structure, examples of the base resin constituting the coating film layers other than the outermost layer include polyurethane, epoxy resin, acrylic resin, vinyl acetate resin, polyester resin, etc., and among these, polyurethane is preferred. Furthermore, the polyurethanes that can be used for the outermost layer described above may also be used as the resin constituting the coating film layers other than the outermost layer.

[0150] The thickness of the coating film formed from the golf ball paint resin is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 9 μm or more, and is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. If the thickness of the coating film is within the above range, the appearance is good.

[0151] When the coating film has a multilayer structure, the total thickness of the coating film is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 9 μm or more, and is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 40 μm or less. If the thickness is within the above range, the appearance is good.

[0152] (Formation of coating film) The coating film can be formed by applying a paint to the surface of the golf ball body. The method for applying the paint is not particularly limited, and any known method can be used, such as spray coating or electrostatic coating.

[0153] In the case of spray coating using an air gun, the polyisocyanate composition and the polyol composition may be supplied by respective pumps and continuously mixed in a line mixer placed just before the air gun, and the resulting mixture may be spray coated, or the polyol composition and the polyisocyanate composition may be spray coated separately using an air spray system equipped with a mixing ratio control mechanism. The coating may be spray coated in one go, or multiple coats may be applied.

[0154] The paint applied to the golf ball body can be dried at a temperature of 30°C to 70°C for 1 hour to 24 hours to form a coating film.

[0155] (golf ball) The golf ball of the present invention is not particularly limited as long as it has a golf ball body including a spherical core, an intermediate layer, and a cover, and at least one coating layer formed on the surface of the golf ball body. The structure of the golf ball body is not particularly limited, and it may be a three-piece golf ball, a four-piece golf ball, or a multi-piece golf ball with five or more pieces. In any case, the present invention can be suitably applied.

[0156] The diameter of the golf ball of the present invention is preferably 40 mm to 45 mm. From the viewpoint of meeting the standards of the United States Golf Association (USGA), the diameter is preferably 42.67 mm or more. From the viewpoint of air resistance, the diameter is preferably 44 mm or less, and more preferably 42.80 mm or less. The mass of the golf ball is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining large inertia, the mass is preferably 44.00 g or more, and more preferably 45.00 g or more. From the viewpoint of meeting the standards of the USGA, the mass is preferably 45.93 g or less.

[0157] For golf balls of the present invention having a diameter of 40 mm to 45 mm, the compressive deformation (amount of shrinkage in the compressive direction) when an initial load of 98 N is applied and a final load of 1275 N is applied is preferably 2.00 mm or more, more preferably 2.05 mm or more, even more preferably 2.10 mm or more, and preferably less than 2.70 mm, more preferably 2.65 mm or less, and even more preferably 2.60 mm or less. Golf balls with a compressive deformation of 2.00 mm or more are not too hard and have a good feel at impact. On the other hand, by keeping the compressive deformation less than 2.70 mm, the initial velocity on driver shots increases, improving distance performance.

[0158] 2 is a partially cutaway cross-sectional view showing a golf ball 1 according to one embodiment of the present invention. Golf ball 1 has a spherical core 2, a mid layer 3 enclosing the spherical core, a cover 4 enclosing the mid layer, and a coating 5 provided on the surface of the cover. A large number of dimples 41 are formed on the surface of the cover. The portions of the surface of the cover other than the dimples 41 are lands 42. [Example]

[0159] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0160] [Evaluation method] (1) Compression deformation (mm) A Yamada compression tester, "SCH," was used to measure the amount of compressive deformation. In this tester, a golf ball or spherical core is placed on a metal hard plate. A metal cylinder is gradually lowered toward the golf ball or spherical core. The golf ball or spherical core, sandwiched between the bottom of the cylinder and the hard plate, deforms. The distance traveled by the cylinder from when an initial load of 98 N was applied to the golf ball or spherical core until a final load of 1275 N was applied, was measured. The amount of compressive deformation (mm) is the travel distance. The speed of the cylinder before the initial load was applied was 0.83 mm / s. The speed of the cylinder after the initial load was applied until the final load was applied was 1.67 mm / s.

[0161] (2) Core hardness (Shore C hardness) The hardness measured at the surface of the core was taken as the core surface hardness. The core was cut into a hemisphere, and the hardness was measured at the center of the cut surface and at a predetermined distance from the center in the radial direction. Each hardness was calculated by measuring the hardness at four points and averaging these values. The hardness was measured using an automatic hardness tester (DigiTest II, manufactured by H. Burleith Co.). A Shore C detector was used.

[0162] (3) Slab hardness (Shore D hardness) of intermediate layer composition The intermediate layer composition was injection molded into a sheet approximately 2 mm thick and stored at 23°C for two weeks. Three or more of these sheets were stacked to avoid the influence of the measurement substrate, and the hardness was measured using an automatic hardness tester (DigiTest II, manufactured by H. Burleith Co.). A Shore D detector was used.

[0163] (4) Number average molecular weight of polyol The polyol was subjected to gel permeation chromatography measurement under the following measurement conditions. <Measurement conditions> Apparatus: Tosoh HLC-8120GPC Eluent: tetrahydrofuran (THF) Temperature: 40℃ Column: TSKgel SuperHM-M (Tosoh Corporation) Polyol concentration: 0.2% by mass (polyol / (polyol + THF)) Sample injection volume: 5 μL Flow rate: 0.5mL / min Molecular weight standard: Polystyrene (Tosoh Corporation, PStQuick Kit-H)

[0164] (5) Slab hardness of cover material (Shore A hardness) The cover material was injection molded into a sheet approximately 2 mm thick and stored at 23°C for two weeks. Three or more sheets were stacked to avoid the influence of the measurement substrate, and the hardness was measured using an automatic hardness tester (DigiTest II, manufactured by H. Burleith). A Shore A detector was used.

[0165] (6) Loss modulus E” (Pa) The loss modulus E" (Pa) of the cover material was measured under the following conditions. Equipment: Dynamic viscoelasticity measuring device "Rheogel-E4000" manufactured by UBM Measurement sample: A sheet with a thickness of 0.5 mm was prepared from the cover material by heat press molding, and a test piece with a width of 4 mm and a clamp distance of 20 mm was cut out from this sheet. <Measurement conditions> Measurement mode: Tensile Measurement temperature: -100℃~100℃ Heating rate: 4°C / min Excitation frequency: 10Hz Measurement distortion: 0.05%

[0166] (7) Tensile test A coating material containing the polyisocyanate composition and the polyol composition was dried and cured at 40°C for 4 hours to form a coating film (thickness 100µm±10µm). A test piece having a width of 4 mm and a length of 30 mm was cut from this coating film, and a tensile test was carried out under the following test conditions using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM). <Test conditions> Chuck distance: 20mm Measurement temperature: 23℃ Deformation increasing tensile speed: 1.1 mm / sec Deformation reduction return speed: 1.1 mm / sec Load data acquisition points per second: 50 Distortion setting value: 10 mm (εmax = 50%)

[0167] (8) Coating thickness (μm) The golf ball was cut into a hemisphere, and the cross section of the coating film on the hemisphere was observed using a microscope (Keyence Corporation, VHX-1000) to determine the coating film thickness. The film thickness measurement locations will be explained with reference to Figures 3 and 4. Figure 3 is a schematic diagram of a cross section of a golf ball. As shown in Figure 3, in the cross section of the golf ball, a line A passing through the center of the ball and the bottom of one of the dimples, a line B perpendicular to line A and passing through the center of the golf ball, and a line C at a 45° angle with line A on the AB plane are drawn, and the intersections of these lines with the coating surface are designated as the pole P, equator E, and shoulder S, respectively.

[0168] FIG. 4 is a schematic diagram of a cross section passing through the bottom De of a dimple 41 and the center of a golf ball 1. The bottom De of a dimple is the deepest part of the dimple 41. The edge Ed is the point of contact between the dimple 41 and the tangent T when a common tangent T is drawn on both sides of the dimple 41. Measurement point Y on the slope is the point where a perpendicular line drawn from the midpoint of the line connecting the bottom De and edge Ed of the dimple intersects with the slope of the dimple toward the dimple 41. Measurement point X on the land is the midpoint between the edges of adjacent dimples. Note that in cases where there is no land area, such as when adjacent dimples are in contact with each other, or where the land area is extremely narrow and it is difficult to measure the film thickness, the measurement points are the bottom, edge, and slope of the dimple.

[0169] For the measurements, test specimens were first prepared from three locations on six balls: the dimple where the pole P was located, and the dimples near the equator E and shoulder S. Next, for each test specimen (dimple), the thickness of the paint film was measured at the dimple bottom De, edge Ed, slope Y, and land X. Finally, the measurements for the six balls were averaged, and this average was used as the paint film thickness.

[0170] (9) Wear resistance of the ball surface A 7-liter ball mill was filled with 2,500 g of abrasive stones (Tipton's "AT3") and 2,500 ml of water. 40 golf balls were placed in the ball mill. The ball mill was operated at a rotation speed of 50 rpm for 1 hour, and the appearance of the golf balls after milling was visually inspected and evaluated as follows: ◎: Fewer than five balls had areas of paint peeling the size of one or more dimples. Good: The number of balls with peeling areas on the paint film the size of one or more dimples is 5 or more but less than 10. △: The number of balls with peeling areas on the paint film the size of one or more dimples is 10 or more but less than 20. ×: 20 or more balls have peeling areas on the paint film that are the size of one or more dimples.

[0171] (10) Contamination resistance against shots from bunkers A sand wedge (manufactured by Cleveland Golf Co., product name "RTX6 ZIPCORE", loft angle: 58°) was attached to a Golf Laboratory swing machine, and golf balls placed in a bunker were hit at a head speed of 16 m / s. Each golf ball was hit 10 times. After hitting, 20 golf players visually inspected the golf balls. The number of players who responded that they were bothered by dirt was counted and evaluated according to the following criteria. ◎: 5 people or less 〇: More than 6 people, less than 10 people △: More than 11 people, less than 15 people ×: 16 or more people

[0172] (11) Approach spin rate from the rough (under crusted conditions) A sand wedge (manufactured by Cleveland Golf Co., product name "RTX6 ZIPCORE", loft angle: 58°) was attached to a Golf Laboratory swing machine, and a golf ball was hit at a head speed of 16 m / s. The spin rate (rpm) of the hit golf ball was measured by taking continuous photographs of the golf ball. Two wild grass leaves (approximately 3 cm long) were attached to the golf ball to be measured, and the ball was hit so that the wild grass was positioned between the club face and the golf ball. Measurements were made 10 times for each golf ball, and the average value was taken as the spin rate. The spin rate of each golf ball in Tables 7 to 9 is shown as the difference from golf ball No. 1 and was evaluated according to the following criteria. ◎: 0 rpm or more 〇: -90 rpm or more, less than 0 rpm △: -180 rpm or more, less than -90 rpm ×: Less than -180 rpm

[0173] (12) Spin rate on 8-iron shots An 8-iron (manufactured by Sumitomo Rubber Industries, Ltd., SRIXON (registered trademark) ZX7MkII, loft 36°, shaft hardness S) was attached to a swing robot M / C manufactured by True Temper, and golf balls were hit at a head speed of 39 m / s, and the spin rate of the golf balls immediately after impact was measured. Measurements were made 10 times for each golf ball, and the average value was used as the measured value for that golf ball. The spin rate of the golf balls immediately after impact was measured by taking continuous photographs of the hit golf balls. The spin rate of each golf ball in Tables 7 to 9 is shown as the difference from golf ball No. 1 and was evaluated according to the following criteria. ◎: 0 rpm or more 〇: -130 rpm or more, less than 0 rpm △: -260 rpm or more, less than -130 rpm ×: Less than -260 rpm

[0174] (13) Driver shot initial velocity, spin rate, and distance A driver (SRIXON (registered trademark) ZX7MkII, manufactured by Sumitomo Rubber Industries, Ltd., loft 10.5°, shaft hardness S) was attached to a swing robot M / C manufactured by True Temper, and golf balls were hit at a head speed of 50 m / s. The ball speed (initial velocity), spin rate, and flight distance (distance from the starting point of launch to the point of landing) immediately after impact were measured. Measurements were performed 10 times for each golf ball, and the average value was used as the measured value for that golf ball. The spin rate of the golf ball immediately after impact was measured by taking continuous photographs of the hit golf ball. The spin rate, initial velocity, and flight distance of each golf ball in Tables 7 to 9 are shown as the difference from golf ball No. 1 and were evaluated according to the following criteria. ◎: 0 yds or more 〇: Over -0.7yd, under 0yd △: -1.4 yd or more, less than -0.7 yd ×: Less than -1.4yd

[0175] (14) Overall rating Each golf ball was evaluated based on the following criteria: abrasion resistance of the ball surface, contamination resistance from shots from the bunker, approach spin rate from the rough (with the ball on the grass), spin rate from an 8-iron shot, and distance from a driver shot. ◯: No △ or × in each evaluation. △: In each evaluation, there is one or more △ but no ×. ×: There is one or more × marks in each evaluation.

[0176] [Manufacturing golf balls] (1) Preparation of spherical cores The raw materials were kneaded with a kneading roll so as to obtain the composition shown in Table 1, thereby obtaining a core composition. The core compositions shown in Table 1 were hot-pressed in upper and lower molds having hemispherical cavities to obtain spherical cores. An appropriate amount of barium sulfate was added so that the mass of the resulting golf ball would be 45.6 g.

[0177] [Table 1]

[0178] The materials used in Table 1 are as follows: Polybutadiene rubber: "BR-730" manufactured by JSR Corporation (high cis polybutadiene rubber, cis-1,4-bond content 95% by mass, 1,2-vinyl bond content 1.3% by mass, Mooney viscosity (ML 1+4 (100℃))55, molecular weight distribution (Mw / Mn)3) Zinc diacrylate: Nisshoku Techno Fine Chemical Co., Ltd., "ZN-DA90S" Zinc oxide: "Ginrei R" manufactured by Toho Zinc Co., Ltd. Barium sulfate: Sakai Chemical Industry Co., Ltd., "Barium Sulfate BD" Benzoic acid: Emerald Kalama Chemical 4-Methoxyphenol: Tokyo Chemical Industry Co., Ltd. H-BHT: Tokyo Materials Co., Ltd., dibutylhydroxytoluene PBDS: Kawaguchi Chemical Industry Co., Ltd., bis(pentabromophenyl) disulfide DPDS: Diphenyl disulfide, manufactured by Sumitomo Seika Chemicals DCP: NOF Corporation, "Percumyl (registered trademark) D", dicumyl peroxide

[0179] (2) Formation of the middle class The raw materials were extruded using a twin-screw kneading extruder so as to have the composition shown in Table 2, to prepare pellets of a composition for an intermediate layer. The obtained intermediate layer composition was injection molded onto the spherical core obtained as described above so as to have a predetermined thickness, thereby coating the spherical core and producing an intermediate layer-coated sphere.

[0180] [Table 2] Himilan® AM7337: Sodium ion-neutralized ethylene-methacrylic acid copolymer ionomer resin, manufactured by Mitsui Dow Polychemicals Himilan (registered trademark) AM7938: Zinc ion-neutralized ethylene-methacrylic acid copolymer ionomer resin, manufactured by Mitsui Dow Polychemicals U161-RV2: Toray Industries, polyamide resin Titanium dioxide: Ishihara Sangyo Kaisha, Ltd., A-220

[0181] (3) Cover formation (Synthesis of polyurethane for cover) The polyurethane for the cover having the composition ratio shown in Table 3 was synthesized as follows. Dicyclohexylmethane diisocyanate (H 12 Polytetramethylene ether glycol (PTMG) heated to 80°C was added to MDI, and the raw material (H 12 Dibutyltin dilaurate (manufactured by Aldrich, dibutyltin dilaurate) was added in an amount of 0.005% by mass of the total amount of MDI, PTMG, and BD, and the mixture was stirred at 80°C for 2 hours under a nitrogen stream. Next, butanediol (BD) heated to 80°C was added under a nitrogen stream, and the mixture was stirred at 80°C for 1 minute. The reaction solution was then cooled, and the pressure was reduced at room temperature for 1 minute to degas the system. The degassed reaction solution was spread in a container and stored under a nitrogen atmosphere at 110°C for 6 hours to carry out a urethanization reaction, thereby obtaining polyurethane.

[0182] [Table 3] PTMG650: Polytetramethylene ether glycol (number average molecular weight: 650) PTMG1000: Polytetramethylene ether glycol (number average molecular weight: 1000) PTMG1400: Polytetramethylene ether glycol (number average molecular weight: 1400) PTMG2000: Polytetramethylene ether glycol (number average molecular weight: 2000) PTMG3000: Polytetramethylene ether glycol (number average molecular weight: 3000) H 12MDI: Dicyclohexylmethane diisocyanate BD: 1,4-butanediol

[0183] According to the formulation shown in Table 4, the cover polyurethane and titanium oxide were dry-blended and mixed in a twin-screw extruder to obtain pelletized cover material. Extrusion was performed with a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D of 35. The compound was heated to 150-230°C at the extruder die. The resulting cover material pellets were placed one at a time in each recess of the lower mold of a half-shell molding die and pressurized to form half shells. Compression molding was performed at a molding temperature of 170°C, a molding time of 5 minutes, and a molding pressure of 2.94 MPa. The mid layer-covered sphere was concentrically covered with two half shells, and the cover was compression molded to obtain a golf ball body at a molding temperature of 145°C for 2 minutes under a molding pressure of 9.8 MPa.

[0184] [Table 4] Titanium dioxide: Ishihara Sangyo Kaisha, Ltd., A-220

[0185] (4) Formation of coating film Preparation of urethane polyols No. 1 to No. 4 Polycarbonate diol (PCD500, PCD800, PCD1000) or polytetramethylene ether glycol (PTMG650) and trimethylolpropane (TMP) were dissolved in solvents (toluene, methyl ethyl ketone) as the first polyol to achieve the blending ratios shown in Table 5. Dibutyltin dilaurate was added as a catalyst to the solution in an amount of 0.1% by mass relative to 100% by mass of the first polyol. While maintaining the polyol solution at 80°C, isophorone diisocyanate (IPDI) as the first polyisocyanate was added dropwise and mixed. After the addition, stirring was continued until the isocyanate was consumed, and then the mixture was cooled to room temperature to prepare a urethane polyol (solid content: 60% by mass). The composition of the resulting urethane polyol is shown in Table 5.

[0186] [Table 5] The materials used in Table 5 are as follows: PCD500: Polycarbonate diol (number average molecular weight 500), manufactured by Asahi Kasei Chemicals Corporation PCD800: Polycarbonate diol (number average molecular weight 800), manufactured by Asahi Kasei Chemicals Corporation PCD1000: Polycarbonate diol (number average molecular weight 1000), manufactured by Asahi Kasei Chemicals Corporation PTMG650: Polyoxytetramethylene glycol (number average molecular weight 650), manufactured by Mitsubishi Chemical Corporation TMP: Trimethylolpropane (molecular weight 134.2), manufactured by Tokyo Chemical Industry Co., Ltd. IPDI: Isophorone diisocyanate (molecular weight 222.3), manufactured by Sumika Covestro Urethane Co., Ltd.

[0187] Preparation of polyol composition (main component) A polyol composition was prepared by mixing 100 parts by mass of the resin component with 100 parts by mass of a solvent (a mixed solvent of xylene and methyl ethyl ketone at a mass ratio of 70 / 30). Dibutyltin dilaurate was added as a catalyst in an amount of 0.1% by mass relative to 100% by mass of the resin component of the polyol composition.

[0188] Preparation of polyisocyanate composition (curing agent) Polyisocyanates were blended in the blending ratios shown in Table 6 to prepare polyisocyanate compositions.

[0189] The following polyisocyanates were used: HDI isocyanurate modified product: isocyanurate modified product of hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals Corporation, Duranate (registered trademark) TKA-100 (NCO content: 21.7% by mass)) HDI adduct modified product: an adduct modified product of hexamethylene diisocyanate (Duranate (registered trademark) E402-80B (NCO content: 7.3% by mass), manufactured by Asahi Kasei Chemicals Corporation) HDI biuret modified product: Biuret modified product of hexamethylene diisocyanate (Duranate (registered trademark) 21S-75E (NCO content: 15.5% by mass), manufactured by Asahi Kasei Chemicals Corporation) IPDI isocyanurate modified product: isocyanurate modified product of isophorone diisocyanate (manufactured by Degussa, VESTANAT (registered trademark) T1890 (NCO content: 12.0% by mass))

[0190] [Table 6]

[0191] A curable coating composition was prepared by blending the polyol composition and polyisocyanate composition as shown in Table 6. The surface of the golf ball body obtained above was sandblasted to form markings, and then the paint was applied with an air gun. The paint was then dried in an oven at 40°C for 24 hours to obtain a golf ball with a diameter of 42.7 mm and a mass of 45.6 g. The coating thickness was 10±2 μm.

[0192] The coating was performed by placing the golf ball body on a rotating body equipped with prongs, rotating the rotating body at 300 rpm, and moving the air gun vertically at a spray distance (7 cm) from the golf ball body. The interval between each recoat was 1.0 second. The air gun spraying conditions were as follows: two recoats, spray air pressure: 0.15 MPa, pressure tank air pressure: 0.10 MPa, application time per coat: 1 second, ambient temperature: 20°C to 27°C, ambient humidity: 65% or less. The results of evaluation of the resulting golf balls are shown in Tables 7 to 9.

[0193] [Table 7]

[0194] [Table 8]

[0195] [Table 9]

[0196] Golf balls Nos. 1 to 17 each have a spherical core having a predetermined hardness distribution, a mid layer having a thickness of 0.70 mm or more and less than 1.30 mm, and a cover having a loss modulus (E -40 )6.50×10 7 ~22.0×10 7 Pa, loss modulus (E -20 )3.50×10 7 ~7.10×10 7 The stress (M10 (kgf / cm)) at 10% strain is 2 )) Stress at deformation reduction is 0kgf / cm 2 The strain (ε1 (%)) at the time of compression satisfies the relationship 0.10≦ε1 / M10≦1.00, and the amount of compressive deformation is 2.00 mm or more and less than 2.70 mm. These golf balls Nos. 1 to 17 have improved surface abrasion resistance and contamination resistance on bunker shots, and offer an excellent balance of overall performance including spin performance on approach shots and middle iron shots and distance performance on driver shots.

[0197] Golf balls Nos. 18 to 22 are cases in which the spherical core does not have a predetermined hardness distribution. Golf ball No. 23 is a golf ball in which the amount of compressive deformation is 2.70 mm or more. Golf ball No. 24 has a mid layer with a thickness of 1.3 mm or more. Golf ball No. 25 had a mid layer thickness of less than 0.70 mm, but cracks occurred after fewer than 10 hits with a driver, making it impossible to evaluate. Golf balls No. 26 to 28 have a loss modulus (E -20) is 3.50 × 10 7 Less than or equal to 7.10 x 10 7 This is the case when the temperature exceeds Pa. These golf balls Nos. 18 to 24 and 26 to 28 do not have a good balance of overall performance in terms of spin performance on approach shots, spin performance on middle iron shots, and distance performance on driver shots.

[0198] Golf balls Nos. 29 and 30 are cases where the coating resin has an ε1 / M10 of more than 1.00. These golf balls Nos. 29 and 30 do not have improved abrasion resistance of the golf ball surface or stain resistance from bunker shots.

[0199] The present invention (1) is a golf ball having a golf ball body including a spherical core, a mid layer enclosing the spherical core, and a cover enclosing the mid layer, and a coating film provided on the surface of the golf ball body, wherein the spherical core has a central hardness (H0), a hardness (H5) at a point 5.0 mm radially from the center of the spherical core, and a hardness (H 10 ), hardness at a radial distance of 15 mm from the center of the spherical core (H 15 ) and surface hardness (Hs) in Shore C hardness satisfy the relationships of the following formulas (1) to (3), the thickness of the intermediate layer is 0.70 mm or more and less than 1.30 mm, and the cover has a loss modulus (E") at a measurement temperature of -40°C measured using a dynamic viscoelasticity device under the following measurement conditions. -40 ) is 6.50×10 7 Pa~22.0×10 7 Pa, and the loss modulus (E -20 ) is 3.50×10 7 Pa ~ 7.10 x 10 7 In a tensile test, a test piece is deformed until the strain reaches a predetermined value εmax, and then the stress is reduced to 0 kgf / cm 2 The deformation is reduced until the stress at 10% strain is M10 (kgf / cm 2) and the stress when the deformation is reduced is 0 kgf / cm 2 The golf ball is formed from a paint resin that satisfies the relationship 0.10≦ε1 / M10≦1.00, where ε1 (%) is the strain at this time, and the golf ball is characterized in that the amount of compressive deformation when a final load of 1275 N is applied from an initial load of 98 N is 2.00 mm or more and less than 2.70 mm. -3.0≦{(H5-H0)-(H 15 -H 10 )}≦3.0 (1) -3.0≦{(H 10 -H5)-(H s -H 15 )}≦3.0 (2) 5.0≦[{(H5-H0)+(H 15 -H 10 )} / 2-{(H 10 -H5)+(Hs-H 15 )} / 2]≦10.0 (3) <Measurement conditions for dynamic viscoelasticity device> Measurement mode: Tensile Measurement temperature: -100℃~100℃ Heating rate: 4°C / min Excitation frequency: 10Hz Measurement distortion: 0.05% <Test conditions for tensile test> Test piece dimensions: width 4 mm, thickness 100 μm ± 10 μm Chuck distance: 20mm Measurement temperature: 23℃ Deformation increasing tensile speed: 1.1 mm / sec Deformation reduction return speed: 1.1 mm / sec Load data acquisition points per second: 50 Distortion setting value: 10 mm (εmax = 50%)

[0200] The present invention (2) is a method for measuring the center hardness (H0), hardness (H5), hardness (H 10 ) and hardness (H 15 ) is a golf ball according to the present invention (1), which satisfies the relationship of the following formula (4) in Shore C hardness: [{(H5-H0)+(H15 -H 10 )} / 2]≧6.0 (4)

[0201] The present invention (3) is a method for manufacturing a hardness tester using the hardness tester (H5) and hardness tester (H 10 ), hardness (H 15 ) and surface hardness (Hs) in Shore C hardness satisfy the relationship of the following formula (5): [{(H 10 -H5)+(Hs-H 15 )} / 2]≦2.0 (5)

[0202] The present invention (4) is a golf ball according to any one of the present inventions (1) to (3), wherein the center hardness (H0) and the surface hardness (Hs) satisfy the relationship of the following formula (6) in Shore C hardness: (Hs-H0)≧18.0 (6)

[0203] Invention (5) is the golf ball according to any one of inventions (1) to (4), wherein the center hardness (H0) is 57.0 or more in Shore C hardness.

[0204] The present invention (6) is the golf ball according to any one of the present inventions (1) to (5), wherein the cover material contains, as a resin component, a cover polyurethane obtained by reacting a polyol with a polyisocyanate, and the polyol constituting the cover polyurethane contains at least one polymer polyol selected from the group consisting of polyether polyols, condensation polyester polyols, lactone polyester polyols, polycarbonate polyols, and acrylic polyols.

[0205] The present invention (7) is a golf ball according to the present invention (6), wherein the polyol constituting the polyurethane for the cover contains a first polymer polyol and a second polymer polyol having a number average molecular weight greater than that of the first polymer polyol.

[0206] The present invention (8) is the golf ball according to the present invention (6) or (7), wherein the content of polyether polyol in 100% by mass of the polyol constituting the polyurethane for the cover is 50% by mass or more.

[0207] The present invention (9) is the golf ball according to any one of the present inventions (1) to (8), wherein the paint resin contains a paint polyurethane as a resin component.

[0208] The present invention (10) is the golf ball according to the present invention (9), wherein the polyol component constituting the polyurethane for paint contains at least one selected from the group consisting of polyether diol, polyester diol, polycaprolactone diol, and polycarbonate diol.

[0209] The present invention (11) is the golf ball according to the present invention (9) or (10), wherein the polyol component constituting the polyurethane paint contains a polycarbonate diol.

[0210] The present invention (12) is a golf ball according to any one of the present inventions (9) to (11), wherein the polyisocyanate component constituting the polyurethane paint contains at least one selected from the group consisting of an isocyanurate-modified product of hexamethylene diisocyanate, an adduct-modified product of hexamethylene diisocyanate, a biuret-modified product of hexamethylene diisocyanate, and an isocyanurate-modified product of isophorone diisocyanate.

[0211] The present invention (13) is the golf ball according to any one of the present inventions (9) to (12), wherein the polyisocyanate component constituting the polyurethane for paint contains hexamethylene diisocyanate.

[0212] The present invention (14) is a golf ball according to any one of the present inventions (9) to (13), wherein the polyisocyanate component constituting the polyurethane for paint contains an isocyanurate-modified product of hexamethylene diisocyanate and an adduct-modified product of hexamethylene diisocyanate. [Explanation of symbols]

[0213] 1: Golf ball, 2: Spherical core, 3: Mid layer, 4: Cover, 5: Coating, 41: Dimples, 42: Land

Claims

1. A golf ball having a golf ball body including a spherical core, a mid layer enclosing the spherical core, and a cover enclosing the mid layer, and a coating film provided on the surface of the golf ball body, The central hardness (H 0 ), hardness (H 5 ), hardness (H 10 ), hardness (H 15 ) and surface hardness (Hs) satisfy the relationships of the following formulas (1) to (3) in Shore C hardness, The thickness of the intermediate layer is 0.70 mm or more and less than 1.30 mm, The cover has a loss modulus (E") at a measurement temperature of -40°C measured using a dynamic viscoelasticity device under the following measurement conditions: -40 ) is 6.50 x 10 7 Pa ~ 22.0 x 10 7 Pa, and the loss modulus (E" -20 ) is 3.50 x 10 7 Pa ~ 7.10 x 10 7 Pa. In a tensile test, the coating film is deformed until the strain reaches a predetermined value εmax, and then the stress is reduced to 0 kgf / cm 2 The deformation is reduced until the stress at which the strain is 10% when the deformation is increased is M10 (kgf / cm 2 ) and the stress when the deformation is reduced is 0 kgf / cm 2 When the strain at time is ε1 (%), the coating material is made of a coating resin that satisfies the relationship 0.10≦ε1 / M10≦1.00, The golf ball is characterized in that the amount of compressive deformation when an initial load of 98 N is applied and a final load of 1275 N is applied is 2.00 mm or more and less than 2.70 mm. -3.0≦{(H 5 -H 0 )-(H 15 -H 10 )}≦3.0 ・・・(1) -3.0≦{(H 10 -H 5 )-(H s -H 15 )}≦3.0 ・・・(2) 5.0≦[{(H 5 -H 0 )+(H 15 -H 10 )} / 2-{(H 10 -H 5 )+(Hs-H 15 )} / 2]≦10.0 ・・・(3) <Measurement conditions for dynamic viscoelasticity device> Measurement mode: Tensile Measurement temperature: -100℃~100℃ Temperature increase rate: 4°C / min Excitation frequency: 10Hz Measured distortion: 0.05% <Test conditions for tensile test> Test piece dimensions: width 4 mm, thickness 100 μm ± 10 μm Distance between chucks: 20 mm Measurement temperature: 23℃ Deformation increase tensile speed: 1.1 mm / sec Deformation reduction return speed: 1.1 mm / sec Load data acquisition points per second: 50 Distortion setting value: 10 mm (εmax = 50%)

2. The center hardness (H 0 ), hardness (H 5 ), hardness (H 10 ) and hardness (H 15 2. The golf ball according to claim 1, wherein the Shore C hardness satisfies the following formula (4): [{(H 5 -H 0 )+(H 15 -H 10 )} / 2]≧6.0 ・・・(4)

3. The hardness (H 5 ), hardness (H 10 ), hardness (H 15 2. The golf ball according to claim 1, wherein the surface hardness (Hs) satisfies the following formula (5) in Shore C hardness: [{(H 10 -H 5 )+(Hs-H 15 )} / 2]≦2.0 ・・・(5)

4. The center hardness (H 0 2. The golf ball according to claim 1, wherein the surface hardness (Hs) satisfies the following formula (6) in Shore C hardness: (Hs-H 0 )≧18.0 ・・・(6)

5. The center hardness (H 0 2. The golf ball according to claim 1, wherein the hardness of said first and second layers is 57.0 or greater in Shore C hardness.

6. the cover material contains, as a resin component, a cover polyurethane obtained by reacting a polyol with a polyisocyanate; 2. The golf ball according to claim 1, wherein the polyol constituting the cover polyurethane contains at least one polymer polyol selected from the group consisting of polyether polyols, condensation polyester polyols, lactone polyester polyols, polycarbonate polyols, and acrylic polyols.

7. 7. The golf ball according to claim 6, wherein the polyol constituting the cover polyurethane comprises a first polymer polyol and a second polymer polyol having a number average molecular weight greater than that of the first polymer polyol.

8. 7. The golf ball according to claim 6, wherein the content of polyether polyol in 100% by weight of the polyol constituting the polyurethane for the cover is 50% by weight or more.

9. 2. The golf ball according to claim 1, wherein the paint resin contains a paint polyurethane as a resin component.

10. 10. The golf ball according to claim 9, wherein the polyol component constituting the polyurethane paint contains at least one selected from the group consisting of polyether diol, polyester diol, polycaprolactone diol, and polycarbonate diol.

11. 11. The golf ball according to claim 10, wherein the polyurethane paint contains a polycarbonate diol as a polyol component.

12. 10. The golf ball according to claim 9, wherein the polyisocyanate component constituting the polyurethane paint contains at least one selected from the group consisting of an isocyanurate-modified hexamethylene diisocyanate, an adduct-modified hexamethylene diisocyanate, a biuret-modified hexamethylene diisocyanate, and an isocyanurate-modified isophorone diisocyanate.

13. 10. The golf ball according to claim 9, wherein the polyurethane paint contains hexamethylene diisocyanate as a polyisocyanate component.

14. 10. The golf ball according to claim 9, wherein the polyisocyanate component constituting the polyurethane paint contains an isocyanurate-modified hexamethylene diisocyanate and an adduct-modified hexamethylene diisocyanate.

Images