JP2023028455A - Golf ball - Google Patents

Abstract

To provide a golf ball 2 which is excellent in all of flight performance at a shot with a driver, flight performance at a shot with a middle iron, hitting feeling at a shot with the driver, and hitting feeling with a putter.SOLUTION: A golf ball 2 includes a core 4, a middle layer 6, and a cover 8. The golf ball 2 satisfies the following mathematical formulas (1) and (2). (Fw/Fwn)≤0.98 (1) (Fw/Fwn)2/(Fp/Fpn)≤0.98 (2) In the mathematical formulas, Fw represents the maximum vertical force of the golf ball 2 measured under a first condition, Fwn represents the maximum vertical force of a standard ball measured under the first condition, Fp represents the maximum vertical force of the golf ball 2 measured under a second condition, and Fpn represents the maximum vertical force of the standard ball measured under the second condition.SELECTED DRAWING: Figure 1

Description

This specification discloses a golf ball having a core, an intermediate layer and a cover.

A golf player's concern with golf balls is flight performance. Golf players prefer golf balls that provide greater flight distance. Golf players also attach great importance to the feel at impact of a golf ball. Players generally prefer a soft feel at impact.

A typical golf ball has a core, an intermediate layer and a cover. A device related to the core, the intermediate layer and the cover is disclosed in Japanese Patent Application Laid-Open No. 2020-171623.

Japanese Patent Application Laid-Open No. 2020-171623

Golf players attach great importance to flight distance on shots with a driver. Players also place importance on flight distance on shots with middle irons.

Golf players attach great importance to feel at impact on shots with a driver. Players also attach great importance to feel at impact in putting.

The present applicant intends to provide a golf ball that is excellent in all of flight performance on driver shots, flight performance on middle iron shots, shot feel on driver shots, and shot feel on putting. .

A preferred golf ball includes a core, an intermediate layer positioned outside the core, and a cover positioned outside the intermediate layer, and satisfies the following formulas (1) and (2).
(Fw/Fwn) ≤ 0.98 (1)
(Fw/Fwn) ² / (Fp/Fpn) ≤ 0.98 (2)
In these formulas, Fw represents the maximum normal force of a golf ball measured under the first condition described below, Fwn represents the maximum normal force of a standard ball measured under this first condition, and Fp represents the maximum normal force of a standard ball measured under this first condition. and Fpn represents the maximum normal force of a standard ball measured under this second condition.

This golf ball is excellent in all of flight performance on driver shots, flight performance on middle iron shots, shot feel on driver shots, and shot feel on putting.

FIG. 1 is a partially cutaway cross-sectional view schematically showing a golf ball according to one embodiment. 2 is a front view showing a driver for evaluation of the golf ball of FIG. 1; FIG. FIG. 3 is a cross-sectional view taken along line III--III in FIG. 4 is a plan view showing a putter for evaluating the golf ball of FIG. 1. FIG. 5 is a cross-sectional view taken along line VV of FIG. 4. FIG.

Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.

The golf ball 2 shown in FIG. 1 includes a spherical core 4, an intermediate layer 6 located outside the core 4, a cover 8 located outside the intermediate layer 6, and a cover 8 located outside the cover 8. and an outer paint layer 12 positioned outside the inner paint layer 10 . The number of paint layers is two. The outer paint layer 12 is the outermost paint layer. The number of paint layers may be one, or three or more. This golf ball 2 has a plurality of dimples 14 on its surface. A portion of the surface of the golf ball 2 other than the dimples 14 is a land 16 . This golf ball 2 has a mark layer (not shown) on the outside of the cover 8 .

The diameter of the golf ball 2 is preferably 40 mm or more and 45 mm or less. A diameter of 42.67 mm or more is particularly preferable from the viewpoint that the standards of the United States Golf Association (USGA) are satisfied. From the viewpoint of air resistance suppression, the diameter is more preferably 44 mm or less, and particularly preferably 42.80 mm or less.

The weight of the golf ball 2 is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining a large inertia, the mass is more preferably 44 g or more, particularly preferably 45.00 g or more. From the viewpoint that the USGA standard is satisfied, the mass is particularly preferably 45.93 g or less.

The core 4 is formed by cross-linking the rubber composition. Preferred base rubbers include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer and natural rubber. From the viewpoint of resilience performance of the core 4, polybutadiene is preferable. When polybutadiene and other rubbers are used together, polybutadiene is preferably the main component. Specifically, the ratio of polybutadiene to the total base rubber is preferably 50% by mass or more, particularly preferably 80% by mass or more. Polybutadiene having a proportion of cis-1,4 bonds of 80% or more is particularly preferred.

The rubber composition of core 4 preferably includes a co-crosslinking agent. A preferable co-crosslinking agent from the viewpoint of durability and resilience performance of the golf ball 2 is a monovalent or divalent metal salt of an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms. Examples of preferred co-crosslinking agents include zinc acrylate, magnesium acrylate, zinc methacrylate and magnesium methacrylate. From the viewpoint of the resilience performance of the core 4, zinc acrylate and zinc methacrylate are particularly preferred.

The rubber composition may contain an α,β-unsaturated carboxylic acid having 2 to 8 carbon atoms and a metal oxide. Both react in the rubber composition to give a salt. This salt functions as a co-crosslinking agent. Preferred α,β-unsaturated carboxylic acids include acrylic acid and methacrylic acid. Preferred metal oxides include zinc oxide and magnesium oxide.

The amount of the co-crosslinking agent is preferably 10 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the base rubber. The golf ball 2 having this amount of 10 parts by mass or more has excellent resilience performance. From this point of view, this amount is more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. A golf ball 2 having this amount of 45 parts by mass or less has excellent feel at impact. From this point of view, this amount is more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less.

Preferably, the rubber composition of core 4 contains an organic peroxide. Organic peroxides function as cross-linking initiators. The organic peroxide contributes to the resilience performance of the core 4. Suitable organic peroxides include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butyl Peroxy)hexane and di-t-butyl peroxide are exemplified. A particularly versatile organic peroxide is dicumyl peroxide.

The amount of the organic peroxide is preferably 0.1 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the base rubber. The golf ball 2 having this amount of 0.1 parts by mass or more has excellent resilience performance. From this point of view, this amount is more preferably 0.3 parts by mass or more, and particularly preferably 0.5 parts by mass or more. A golf ball 2 having this amount of 3.0 parts by mass or less has excellent feel at impact. From this point of view, this amount is more preferably 2.5 parts by mass or less, and particularly preferably 2.0 parts by mass or less.

Preferably, the rubber composition of core 4 includes an organic sulfur compound. The organic sulfur compound contributes to the resilience performance of the core 4 . Organic sulfur compounds include naphthalenethiol-based compounds, benzenethiol-based compounds and disulfide-based compounds.

Naphthalene-based compounds such as 1-naphthalene, 2-naphthalene, 4-chloro-1-naphthalene, 4-bromo-1-naphthalene, 1-chloro-2-naphthalene, 1-bromo-2-naphthalene Thiol, 1-fluoro-2-naphthalenethiol, 1-cyano-2-naphthalenethiol and 1-acetyl-2-naphthalenethiol are exemplified.

Benzenethiol compounds include benzenethiol, 4-chlorobenzenethiol, 3-chlorobenzenethiol, 4-bromobenzenethiol, 3-bromobenzenethiol, 4-fluorobenzenethiol, 4-iodobenzenethiol, and 2,5-dichlorobenzenethiol. , 3,5-dichlorobenzenethiol, 2,6-dichlorobenzenethiol, 2,5-dibromobenzenethiol, 3,5-dibromobenzenethiol, 2-chloro-5-bromobenzenethiol, 2,4,6-tri chlorobenzenethiol, 2,3,4,5,6-pentachlorobenzenethiol, 2,3,4,5,6-pentafluorobenzenethiol, 4-cyanobenzenethiol, 2-cyanobenzenethiol, 4-nitrobenzenethiol and 2 -Nitrobenzenethiol is exemplified.

Disulfide compounds include diphenyl disulfide, bis(4-chlorophenyl) disulfide, bis(3-chlorophenyl) disulfide, bis(4-bromophenyl) disulfide, bis(3-bromophenyl) disulfide, bis(4-fluorophenyl) disulfide , bis(4-iodophenyl) disulfide, bis(4-cyanophenyl) disulfide, bis(2,5-dichlorophenyl) disulfide, bis(3,5-dichlorophenyl) disulfide, bis(2,6-dichlorophenyl) disulfide, bis (2,5-dibromophenyl) disulfide, bis(3,5-dibromophenyl) disulfide, bis(2-chloro-5-bromophenyl) disulfide, bis(2-cyano-5-bromophenyl) disulfide, bis(2 ,4,6-trichlorophenyl)disulfide, bis(2-cyano-4-chloro-6-bromophenyl)disulfide, bis(2,3,5,6-tetrachlorophenyl)disulfide, bis(2,3,4, 5,6-pentachlorophenyl)disulfide and bis(2,3,4,5,6-pentabromophenyl)disulfide are exemplified.

From the viewpoint of resilience performance, the amount of the organic sulfur compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and particularly preferably 0.3 parts by mass or more with respect to 100 parts by mass of the base rubber. . From the viewpoint of soft feel at impact, this amount is preferably 1.5 parts by mass or less, more preferably 1.0 parts by mass or less, and particularly preferably 0.8 parts by mass or less. Two or more organic sulfur compounds may be used in combination.

The rubber composition of core 4 may contain a carboxylic acid or a carboxylic acid salt. Carboxylic acid and carboxylate can contribute to optimizing the hardness distribution of the core 4 . Preferred carboxylic acids include benzoic acid. Preferred carboxylates include zinc octoate and zinc stearate.

The rubber composition of the core 4 may contain a filler for the purpose of adjusting the specific gravity. Suitable fillers are exemplified by zinc oxide, barium sulfate, calcium carbonate and magnesium carbonate. The amount of filler is appropriately determined so that the intended specific gravity of the core 4 is achieved.

The rubber composition of the core 4 may contain appropriate amounts of various additives such as sulfur, antioxidants, colorants, plasticizers and dispersants. The rubber composition may contain crosslinked rubber powder or synthetic resin powder.

The diameter D1 of the core 4 is preferably 35.0 mm or more and 40.7 mm or less. A golf ball 2 having a core 4 with a diameter D1 of 35.0 mm or more has excellent resilience performance. From this point of view, the diameter D1 is more preferably 37.0 mm or more, and particularly preferably 38.0 mm or more. A golf ball 2 having a core 4 with a diameter D1 of 40.7 mm or less has excellent durability. From this point of view, the diameter D1 is more preferably 40.3 mm or less, particularly preferably 40.0 mm or less.

The center hardness H1o of the core 4 is preferably 45 or more and 70 or less. A golf ball 2 having a core 4 with a center hardness H1o of 45 or more has excellent resilience performance. From this point of view, the center hardness H1o is more preferably 48 or more, particularly preferably 50 or more. A golf ball 2 having a core 4 with a center hardness H1o of 70 or less has excellent feel at impact. From this point of view, the center hardness H1o is more preferably 67 or less, particularly preferably 65 or less.

The center hardness H1o is measured by a Shore C type hardness tester attached to an automatic hardness tester (trade name "Digitest II" by H. Burleith). This hardness tester is pressed against the center of the cross section of the hemisphere obtained by cutting the golf ball 2 . Measurements are made in an environment of 23°C.

The hardness H1 ₍₁₀₎ of the core 4 at a point 10 mm from the center is preferably 55 or more and 85 or less. A golf ball 2 having a core 4 with a hardness H1 ₍₁₀₎ of 55 or more has excellent resilience performance. From this point of view, the hardness H1 ₍₁₀₎ is more preferably 58 or more, particularly preferably 60 or more. A golf ball 2 having a core 4 with a hardness H1 ₍₁₀₎ of 85 or less has excellent feel at impact. From this point of view, the hardness H1 ₍₁₀₎ is more preferably 82 or less, particularly preferably 80 or less.

The hardness H1 ₍₁₀₎ is measured by a Shore C type hardness tester attached to an automatic hardness tester (trade name "Digitest II" by H. Burleith). This hardness tester is pressed at a position 10 mm away from the center of a hemispherical section obtained by cutting the golf ball 2 . Measurements are made in an environment of 23°C.

The surface hardness H1s of the core 4 is preferably 70 or more and 90 or less. A golf ball 2 having a core 4 with a surface hardness H1s of 70 or more has excellent resilience performance. From this point of view, the surface hardness H1s is more preferably 73 or higher, particularly preferably 75 or higher. A golf ball 2 having a core 4 with a surface hardness H1s of 90 or less has excellent feel at impact. From this point of view, the surface hardness H1s is more preferably 87 or less, particularly preferably 85 or less.

The surface hardness H1s is measured by a Shore C type hardness tester attached to an automatic hardness tester (trade name “Digitest II” by H. Burleith). This hardness tester is pressed against the surface of the core 4 . Measurements are made in an environment of 23°C.

The difference (H1s-H1o) between the surface hardness H1s and the center hardness H1o is preferably 14 or more. A golf ball 2 having a core 4 with a difference (H1s-H1o) of 14 or more has excellent flight performance on shots with a driver and a middle iron. This golf ball 2 also has an excellent feel at impact on driver shots and putting. From these points of view, the difference (H1s-H1o) is more preferably 16 or more, particularly preferably 18 or more. From the viewpoint of durability of the golf ball 2, the difference (H1s-H1o) is preferably 30 or less.

The difference (H1s−H1 ₍₁₀₎ ) between the surface hardness H1s and the hardness H1 ₍₁₀ ) at a point 10 mm from the center is preferably 7 or more. A golf ball 2 having a core 4 with a difference (H1s−H1 ₍₁₀₎ ) of 7 or more has a small spin on shots with a driver, and therefore has excellent flight performance. This golf ball 2 also has an excellent feel at impact on driver shots and putting. From these points of view, the difference (H1s−H1 ₍₁₀₎ ) is more preferably 8 or more, particularly preferably 9 or more. From the viewpoint of durability of the golf ball 2, the difference (H1s-H1 ₍₁₀₎ ) is preferably 15 or less.

The mass of the core 4 is preferably 10 g or more and 42 g or less. The cross-linking temperature of the core 4 is typically 140° C. or higher and 180° C. or lower. The cross-linking time of the core 4 is typically 10 minutes or more and 60 minutes or less.

The intermediate layer 6 is positioned outside the core 4 . The intermediate layer 6 is molded from a thermoplastic resin composition. Examples of base polymers for this resin composition include ionomer resins, thermoplastic polyester elastomers, thermoplastic polyamide elastomers, thermoplastic polyurethane elastomers, thermoplastic polyolefin elastomers, and thermoplastic polystyrene elastomers. In particular, ionomer resins are preferred. Ionomer resins are highly elastic. A golf ball 2 having an intermediate layer 6 containing an ionomer resin has excellent resilience performance. This golf ball 2 has excellent flight performance.

The ionomer resin and other resins may be used in combination. When used in combination, the ionomer resin is the main component of the base polymer from the viewpoint of resilience performance. The ratio of the ionomer resin to the total base polymer is preferably 50% by mass or more.

Preferred ionomer resins include binary copolymers of α-olefins and α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms. A preferred binary copolymer contains 80% to 90% by weight α-olefin and 10% to 20% by weight α,β-unsaturated carboxylic acid. This binary copolymer has excellent resilience performance. Another preferred ionomer resin is a ternary combination of an α-olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. polymers. A preferred terpolymer is 70% by mass or more and 85% by mass or less of α-olefin, 5% by mass or more and 30% by mass or less of α,β-unsaturated carboxylic acid, and 1% by mass or more and 25% by mass or less of and α,β-unsaturated carboxylic acid esters. This terpolymer has excellent resilience performance. Preferred α-olefins are ethylene and propylene and preferred α,β-unsaturated carboxylic acids are acrylic acid and methacrylic acid in the bi- and terpolymers. A particularly preferred ionomer resin is a copolymer of ethylene and acrylic acid. Another particularly preferred ionomer resin is a copolymer of ethylene and methacrylic acid.

In bi- and terpolymers, some of the carboxyl groups are neutralized with metal ions. Examples of metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions and neodymium ions. Neutralization may be done with two or more metal ions. Particularly suitable metal ions from the viewpoint of resilience performance and durability of the golf ball 2 are sodium ions, zinc ions, lithium ions and magnesium ions.

Specific examples of ionomer resins include DuPont Mitsui Polychemicals' product names "Himilan 1555," "Himilan 1557," "Himilan 1605," "Himilan 1706," "Himilan 1707," "Himilan 1856," and "Himilan 1855." "Himilan AM7311", "Himilan AM7315", "Himilan AM7317", "Himilan AM7329" and "Himilan AM7337"; DuPont trade names "Surlyn 6120", "Surlyn 6910", "Surlyn 7930", "Surlyn 7940", "Surlyn 8140", "Surlyn 8150", "Surlyn 8940", "Surlyn 8945", "Surlyn 9120", "Surlyn 9150", "Surlyn 9910", "Surlyn 9945", "Surlyn AD8546", "HPF1000" and " HPF2000"; and the ExxonMobil Chemical Company trade names "IOTEK7010", "IOTEK7030", "IOTEK7510", "IOTEK7520", "IOTEK8000" and "IOTEK8030". Two or more ionomer resins may be used in combination.

The resin composition of the intermediate layer 6 may contain appropriate amounts of colorants, fillers, dispersants, antioxidants, ultraviolet absorbers, light stabilizers, fluorescent agents, fluorescent whitening agents, and the like. If the hue of golf ball 2 is white, a typical coloring agent is titanium dioxide.

The thickness T2 of the intermediate layer 6 is preferably 0.5 mm or more and 2.0 mm or less. A golf ball 2 having a thickness T2 of 0.5 mm or more has excellent resilience performance. From this point of view, the thickness T2 is more preferably 0.7 mm or more, and particularly preferably 0.9 mm or more. A golf ball 2 having a thickness T2 of 2.0 mm or less has excellent feel at impact. From this point of view, the thickness T2 is preferably 1.7 mm or less, particularly preferably 1.5 mm or less. Thickness T2 is measured directly under land 16 .

The material hardness H2 of the intermediate layer 6 is preferably 55 or more and 75 or less. A golf ball 2 having a hardness H2 of 55 or more has excellent resilience performance. From this point of view, the hardness H2 is more preferably 58 or higher, and particularly preferably 60 or higher. A golf ball 2 having a hardness H2 of 75 or less has excellent feel at impact. From this point of view, the hardness H2 is more preferably 72 or less, and particularly preferably 70 or less.

The hardness H2 of the intermediate layer 6 is measured according to the specification of "ASTM-D 2240-68". The hardness H2 is measured by a Shore D type hardness tester attached to an automatic hardness tester (trade name “Digitest II” by H. Burleith). A sheet having a thickness of about 2 mm and made of the same material as that of the intermediate layer 6 and formed by hot pressing is used for the measurement. Sheets are stored at a temperature of 23° C. for two weeks prior to measurement. When measuring, three sheets are superimposed.

The surface hardness H2s of the intermediate layer 6 is preferably 85 or more and 100 or less. A golf ball 2 having a surface hardness H2s of 85 or more has excellent resilience performance. From this point of view, the surface hardness H2s is more preferably 88 or higher, particularly preferably 90 or higher. A golf ball 2 having a surface hardness H2s of 100 or less has excellent feel at impact. From this point of view, the surface hardness H2s is more preferably 98 or less, particularly preferably 96 or less.

The surface hardness H2s is measured by a Shore C type hardness tester attached to an automatic hardness tester (trade name "Digitest II" by H. Burleith). This hardness tester is pressed against the surface of the sphere consisting of core 4 and intermediate layer 6 . Measurements are made in an environment of 23°C.

The cover 8 is molded from a resin composition. Examples of base polymers for this resin composition include polyurethanes, ionomer resins, polyesters, polyamides, polyolefins and polystyrenes. Polyurethane is a preferred base polymer from the viewpoint of feel at impact and spin performance. When polyurethane and other resins are used together for the cover 8, the ratio of polyurethane to the total base resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

The resin composition of the cover 8 may contain thermoplastic polyurethane or thermosetting polyurethane. From the viewpoint of productivity of the golf ball 2, thermoplastic polyurethane is preferable. Thermoplastic polyurethanes contain polyurethane components as hard segments and polyester or polyether components as soft segments. Thermoplastic polyurethanes are flexible. The cover 8 using this polyurethane has excellent scratch resistance.

Thermoplastic polyurethane has urethane bonds in the molecule. This urethane linkage can be formed by the reaction of a polyol and a polyisocyanate. A polyol, which is a raw material for urethane bonds, has a plurality of hydroxyl groups. Low molecular weight polyols and high molecular weight polyols can be used.

Low molecular weight polyols include diols, triols, tetraols and hexaols. Specific examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, dipropylene glycol and 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 1,6-cyclohexanedimethylol. Aniline-based diols or bisphenol A-based diols may be used. Specific examples of triols include glycerin, trimethylolpropane and hexanetriol. Specific examples of tetraols include pentaerythritol and sorbitol.

Polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG) and polytetramethylene ether glycol (PTMG) as high molecular weight polyols; polyethylene adipate (PEA), polybutylene adipate (PBA); ) and polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. Two or more polyols may be used in combination. From the viewpoint of feel at impact of the golf ball 2, the number average molecular weight of the high molecular weight polyol is preferably 400 or more, more preferably 1000 or more. The number average molecular weight is preferably 10,000 or less.

Aromatic diisocyanates, alicyclic diisocyanates and aliphatic diisocyanates are exemplified as polyisocyanates that are raw materials for urethane bonds. Two or more diisocyanates may be used in combination.

As aromatic diisocyanates, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4, Examples include 4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI) and paraphenylene diisocyanate (PPDI). Hexamethylene diisocyanate (HDI) is exemplified as an aliphatic diisocyanate. 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), 1,3-bis(isocyanatomethyl)cyclohexane (H ₆ XDI), isophorone diisocyanate (IPDI) and trans-1,4-cyclohexane as cycloaliphatic diisocyanates Diisocyanate (CHDI) is exemplified. 4,4'-dicyclohexylmethane diisocyanate is preferred.

Specific examples of thermoplastic polyurethanes include BASF Japan's trade names "Elastollan NY80A", "Elastollan NY82A", "Elastollan NY83A", "Elastollan NY84A", "Elastollan NY85A", "Elastollan NY88A", "Elastollan NY90A", "Elastollan NY95A", "Elastran NY97A", "Elastollan NY585" and "Elastollan KP016N"; be done.

The resin composition of the cover 8 may contain appropriate amounts of colorants, fillers, dispersants, antioxidants, ultraviolet absorbers, light stabilizers, fluorescent agents, fluorescent whitening agents, lubricants, and the like. If the hue of golf ball 2 is white, a typical coloring agent is titanium dioxide.

The thickness T3 of the cover 8 is preferably 0.3 mm or more and 1.5 mm or less. A golf ball 2 having a thickness T3 of 0.3 mm or more is excellent in controllability and feel at impact. From this point of view, the thickness T3 is more preferably 0.4 mm or more, and particularly preferably 0.5 mm or more. A golf ball 2 having a thickness T3 of 1.5 mm or less has excellent resilience performance. From this point of view, the thickness T3 is more preferably 1.0 mm or less, and particularly preferably 0.8 mm or less. Thickness T3 is measured directly under land 16 .

The material hardness H3 of the cover 8 is preferably 20 or more and 45 or less. A golf ball 2 having a hardness H3 of 20 or more has excellent durability. From this point of view, the hardness H3 is more preferably 25 or higher, and particularly preferably 28 or higher. A golf ball 2 having a hardness H3 of 45 or less is excellent in controllability and feel at impact. From this point of view, the hardness H3 is more preferably 40 or less, and particularly preferably 35 or less.

The hardness H3 of the cover 8 is measured according to the provisions of "ASTM-D 2240-68". The hardness H3 is measured by a Shore D type hardness tester attached to an automatic hardness tester (trade name "Digitest II" by H. Burleith). A sheet having a thickness of about 2 mm and made of the same material as that of the cover 8 and formed by hot pressing is used for the measurement. Sheets are stored at a temperature of 23° C. for two weeks prior to measurement. When measuring, three sheets are superimposed.

The surface hardness H3s of the cover 8 is preferably 70 or more and 95 or less. A golf ball 2 having a surface hardness H3s of 70 or more has excellent resilience performance. From this point of view, the surface hardness H3s is more preferably 75 or higher, particularly preferably 80 or higher. A golf ball 2 having a surface hardness H3s of 95 or less has excellent feel at impact. From this point of view, the surface hardness H3s is more preferably 92 or less, particularly preferably 90 or less.

The surface hardness H3s is measured by a Shore C type hardness tester attached to an automatic hardness tester (trade name "Digitest II" by H. Burleith). This hardness tester is pressed against the surface of the sphere consisting of core 4 , intermediate layer 6 and cover 8 . Measurements are made in an environment of 23°C.

Golf ball 2 may include a reinforcing layer between intermediate layer 6 and cover 8 . The reinforcing layer firmly adheres to the intermediate layer 6 and also to the cover 8 . The reinforcing layer suppresses peeling of the cover 8 from the intermediate layer 6 . The reinforcing layer is made of a resin composition. Examples of preferred base polymers for the reinforcing layer include two-component curing type epoxy resins and two-component curing type urethane resins. The thickness of the reinforcing layer is preferably 5 μm or more and 30 μm or less.

The ratio of the total (T2+T3) of the thickness T2 of the intermediate layer 6 and the thickness T3 of the cover 8 to the diameter D1 of the core 4 ((T2+T3)/D1) is preferably 0.042 or less. A golf ball 2 having this ratio of 0.042 or less has excellent flight performance on shots with a driver and a middle iron. From this point of view, the ratio ((T2+T3)/D1) is more preferably 0.040 or less, particularly preferably 0.038 or less. From the viewpoint of durability of the golf ball 2, this ratio ((T2+T3)/D1) is preferably 0.032 or more.

The ratio (H2/H3) between the hardness H2 of the intermediate layer 6 and the hardness H3 of the cover 8 is preferably 1.80 or more. A golf ball 2 having a ratio (H2/H3) of 1.80 or more has excellent flight performance on shots with a driver and a middle iron. This golf ball 2 also has an excellent feel at impact in putting. From these points of view, the ratio (H2/H3) is more preferably 2.00 or more, particularly preferably 2.10 or more. This ratio (H2/H3) is preferably 3.00 or less.

Preferably, the surface hardness H2s of the intermediate layer 6 is greater than the surface hardness H1s of the core 4 and greater than the surface hardness H3s of the cover 8 . This golf ball 2 has excellent flight performance on shots with a driver and a middle iron. This golf ball 2 also has an excellent feel at impact on driver shots and putting. From these viewpoints, the difference (H2s-H1s) is preferably 6 or more, more preferably 9 or more, and particularly preferably 11 or more. The difference (H2s-H1s) is preferably 20 or less. The difference (H2s-H3s) is preferably 3 or more, more preferably 5 or more, and particularly preferably 7 or more. The difference (H2s-H3s) is preferably 15 or less.

The inner paint layer 10 is formed from a resin composition. Examples of base resins for this resin composition include urethane resins, epoxy resins, acrylic resins, vinyl acetate resins, polyester resins, and the like. A particularly preferred base resin is a urethane resin. The thickness of the inner paint layer 10 is preferably 5 μm or more and 20 μm or less.

The outer paint layer 12 is formed from a resin composition. Examples of base resins for this resin composition include urethane resins, epoxy resins, acrylic resins, vinyl acetate resins, polyester resins, and the like. A particularly preferred base resin is a urethane resin. The thickness of the outer paint layer 12 is preferably 5 μm or more and 20 μm or less.

Typically, inner paint layer 10 is formed from a polyurethane paint and outer paint layer 12 is formed from another polyurethane paint. A preferred polyurethane paint has a base agent and a curing agent. The main agent is the polyol composition (A), and the curing agent is the polyisocyanate composition (B).

Polyol composition (A) contains a polyol compound. A polyol compound has two or more hydroxyl groups in the molecule. It may be a polyol compound (a1) having a hydroxyl group at the end of the molecular chain, or a polyol compound (a2) having a hydroxyl group other than the end of the molecular chain. The polyol composition (A) may have two or more polyol compounds.

Examples of the polyol compound (a1) having a hydroxyl group at the end of the molecular chain include 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. Examples of other polyol compounds (a1) having a hydroxyl group at the end of the molecular chain include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, urethane polyols and acrylic polyols. Examples of polyether polyols include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG) and polyoxytetramethylene glycol (PTMG). Examples of polyester polyols include polyethylene adipate diol, polybutylene adipate diol and polyhexamethylene adipate diol. Poly-ε-caprolactone diol is exemplified as polycaprolactone polyol. Polyhexamethylene carbonate diol is exemplified as polycarbonate polyol.

Examples of the polyol compound (a2) having a hydroxyl group other than at the terminal end of the molecule include a modified polyrotaxane having a hydroxyl group and a hydroxyl group-modified vinyl chloride/vinyl acetate copolymer.

Polyisocyanate composition (B) contains a polyisocyanate compound. A polyisocyanate compound has two or more isocyanate groups. As polyisocyanate compounds, 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 MDI), hydrogenated xylylene diisocyanate (H ₆ XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and norbornene diisocyanate (NBDI). and triisocyanates such as allophanates, burettes, isocyanurates and adducts of diisocyanates. The polyisocyanate composition (B) may contain two or more polyisocyanate compounds.

The indentation depth of the outer paint layer 12 is preferably 300 nm or more. The golf ball 2 having the outer paint layer 12 with a depression depth of 300 nm or more has excellent feel at impact on driver shots and putting. From this point of view, the indentation depth is more preferably 500 nm or more, and particularly preferably 700 nm or more. From the viewpoint of durability of the outer paint layer 12, the indentation depth is preferably 3000 nm or less.

In measuring the depth of indentation, the golf ball 2 is cracked to obtain a hemisphere. A cross section passing through the center of the golf ball 2 is exposed in this hemisphere. This cross section includes the cross section of the outer paint layer 12 . A cryomicrotome makes a horizontal cross-section of this hemisphere. A nanoindenter indenter is applied to the cross-section of the outer paint layer 12 and pressed in a direction perpendicular to the cross-section. The pressing advances the indenter. Pressing is continued until the load of the indenter reaches 50 mgf. The travel distance of the indenter when the load is 30 mgf is measured as the indentation depth. The measurement conditions are as follows.
Nanoindenter: "ENT-2100" by Elionix Co., Ltd.
Temperature: 30°C
Indenter: Berkovich indenter (65.03° As (h) = 26.43h2)
Number of divisions: 500 steps Step interval: 20msec (100mgf)

The compressive deformation amount CD of the golf ball 2 is preferably 3.00 mm or more. A golf ball 2 having a compressive deformation amount CD of 3.00 mm or more has excellent feel at impact on driver shots and putting. From this point of view, the compressive deformation amount CD is more preferably 3.15 mm or more, and particularly preferably 3.25 mm or more. From the viewpoint of flight performance on shots with a driver and middle iron, the amount of compression deformation CD is preferably 4.00 mm or less.

The amount of compression deformation CD is measured by a YAMADA type compression tester "SCH". For measurement, the golf ball 2 is placed on a rigid metal plate. A metal cylinder gradually descends toward the golf ball 2 . The golf ball 2 sandwiched between the bottom surface of the cylinder and the rigid plate is deformed. The distance traveled by the cylinder from the initial load of 98N to the final load of 1275N on the golf ball 2 is measured. The moving speed of the cylinder until the initial load is applied is 0.83 mm/s. The moving speed of the cylinder from when the initial load is applied to when the final load is applied is 1.67 mm/s.

In this specification, the maximum normal force of the golf ball 2 is measured under the first condition and the second condition. The maximum normal force of the standard ball is also measured herein at the first and second conditions.

The specifications of this standard ball are as follows.
Core diameter: 39.0mm
Center hardness: 62 (Shore C)
Hardness at 10 mm distance from center: 71 (Shore C)
Surface hardness: 78 (Shore C)
Intermediate layer thickness: 1.4 mm
Material hardness: 71 (Shore D)
Surface hardness: 97 (Shore C)
Cover thickness: 0.5mm
Material hardness: 40 (Shore D)
Surface hardness: 87 (Shore C)
Paint layer thickness: 10 μm
Indentation depth: 971 nm
Amount of compression deformation CDn: 3.12 mm

In the production of this standard ball, 100 parts by mass of high cis polybutadiene (JSR company's trade name "BR-60"), 24.3 parts by mass of zinc acrylate, 5.0 parts by mass of zinc oxide, 12.4 parts by mass Parts of barium sulfate and 0.6 parts by mass of dicumyl peroxide (DCP) are kneaded to obtain a rubber composition. This rubber composition is put into a mold consisting of an upper mold and a lower mold both having hemispherical cavities and heated to obtain a core having a diameter of 39.0 mm. 50 parts by mass of ionomer resin ("Surlyn 8150" described above), 50 parts by mass of another ionomer resin ("Surly 9150" described above), 4 parts by mass of titanium dioxide and 9 parts by mass of barium sulfate are subjected to twin-screw kneading extrusion. It is kneaded in a machine to obtain a resin composition. The core is put into a mold consisting of an upper mold and a lower mold, each having a hemispherical cavity. A resin composition is coated around the core by an injection molding method to form an intermediate layer. The thickness of this intermediate layer is 1.4 mm. The aforementioned PTMG and TDI are kneaded in a ratio capable of achieving a Shore D hardness of 40 to obtain a resin composition. A final mold comprising an upper mold and a lower mold having a hemispherical cavity and numerous pimples on the cavity surface is heated to 80° C. or higher and 100° C. or lower. A resin composition is put into this final mold, and a sphere having a core and an intermediate layer is put into it, and a cover is formed by compression molding. The thickness of this cover is 0.5 mm. The cover is formed with dimples having a shape that is the inverse of the shape of the pimples. A clear coating based on a two-component curing type polyurethane is applied around the cover. The paint is allowed to dry and a standard golf ball is obtained.

In the first condition, the golf ball 2 or standard ball is hit with the driver 18 (W#1, trade name "XXIO 11" of Sumitomo Rubber Industries, Ltd.) shown in FIGS. Also shown in FIG. 3 is an acceleration sensor 20 (B&K trade name “#4393”). This driver 18 has a head 22 and a shaft 24 . The loft angle of the head 22 is 10.5°, and the hardness of the shaft 24 is S. The product number of the shaft 24 is MP1100. Head 22 includes face 26 , crown 28 and sole 30 . Face 26 has a toe endpoint 32 , a heel endpoint 34 , a top edge line 36 and a bottom edge line 38 . Reference CP in FIGS. 2 and 3 represents the center point of face 26 . The center point CP is on the centerline CL. The distance from the centerline CL to the heel side endpoint 34 is equal to the distance from the centerline CL to the toe side endpoint 32 . The distance from the center point CP to the intersection of the center line CL and the bottom edge line 38 is equal to the distance from the center point CP to the intersection of the center line CL and the top edge line 36 . A virtual line L1 shown in FIG. 3 passes through the center point CP and is orthogonal to the face 26. As shown in FIG. The acceleration sensor 20 is fixed to the sole 30 at the intersection of the virtual line L1 and the outer surface of the sole 30 .

This driver 18 is attached to a swing machine (Golf Laboratory). A golf ball 2 or a standard ball is hit with a driver 18 at a head speed of 40 m/s. The hitting point in this hitting is the center point CP. The acceleration sensor 20 measures the acceleration in the hitting direction at the time of this hitting. The product of the total mass of the head 22 and the acceleration sensor 20 and the acceleration is the vertical force. The contact time is the time from when the normal force occurs to when the normal force disappears. The maximum normal force during the contact time is the maximum normal force. The average value of the data obtained for 12 hits is calculated.

In the second condition, a golf ball 2 or a standard ball is hit with a putter 40 (trade name “Huntington Beach Soft Putter #4” by Cleveland Golf Company) shown in FIGS. 4 and 5 also show an acceleration sensor 42 (trade name "356A01" manufactured by Toyo Technica Co., Ltd.). This putter 40 has a head 44 and a shaft 46 . Head 44 includes face 48 and sole 50 . Face 48 has a toe endpoint 52 , a heel endpoint 54 and a bottom edge line 56 . Reference CP in FIGS. 4 and 5 represents the center point of face 48 . The center point CP is on the centerline CL. The distance from the centerline CL to the heel side endpoint 54 is equal to the distance from the centerline CL to the toe side endpoint 52 . The distance from the bottom edge line 56 to the center point CP is 20 mm. An acceleration sensor 42 is fixed to the head 44 behind the center point CP.

This putter 40 is attached to a swing machine (Golf Laboratory). A golf ball 2 or a standard ball is hit with a putter 40 on a horizontal green with a speed of 10.0 m as measured by a stipometer and a rolling distance of 15 m. The hitting point in this hitting is the center point CP. The acceleration sensor 42 measures the acceleration in the hitting direction at the time of the hitting. The product of the total mass of head 44 and accelerometer 42 and the acceleration is the normal force. The contact time is the time from when the normal force occurs to when the normal force disappears. The maximum normal force during the contact time is the maximum normal force. The average value of the data obtained for 12 hits is calculated.

The golf ball 2 according to this embodiment satisfies the following formulas (1) and (2).
(Fw/Fwn) ≤ 0.98 (1)
(Fw/Fwn) ² / (Fp/Fpn) ≤ 0.98 (2)
Fw: maximum vertical force of the golf ball 2 measured under the first condition Fwn: maximum vertical force of the standard ball measured under the first condition Fp: maximum vertical force of the golf ball 2 measured under the second condition Fpn: Maximum normal force of standard ball measured under second condition

A driver shot of the golf ball 2 that satisfies the above formula (1) achieves a soft feel at impact. In the golf ball 2 that satisfies the above formula (2), both a soft shot feel on driver shots and a soft shot feel on putting are achieved. With this golf ball 2, the flight performance on shots with the driver 18 and middle irons is not hindered.

In the golf ball 2 that satisfies the above formula (1), the ratio (Fw/Fwn) is 0.98 or less. From the viewpoint of feel at impact on driver shots, the ratio (Fw/Fwn) is more preferably 0.96 or less, particularly preferably 0.94 or less. The ratio (Fw/Fwn) is preferably 0.85 or more.

In the golf ball 2 that satisfies the above formula (2), the ratio ((Fw/Fwn) ² /(Fp/Fpn)) is 0.98 or less. From the viewpoint of feel at impact on driver shots and putting, the ratio ((Fw/Fwn) ² /(Fp/Fpn)) is more preferably 0.96 or less, particularly preferably 0.95 or less. The ratio ((Fw/Fwn) ² /(Fp/Fpn)) is preferably 0.85 or more.

As a means to achieve the above formulas (1) and (2),
(a) The hardness difference (H1s-H1o) of the core 4 is set large.
(b) The hardness difference (H1s-H1 ₍₁₀₎ ) of the core 4 is set large.
(c) The ratio (H2/H3) between the hardness H2 of the intermediate layer 6 and the hardness H3 of the cover 8 is set large.
(d) The ratio of the sum (T2+T3) of the thickness T2 of the intermediate layer 6 and the thickness T3 of the cover 8 to the diameter D1 of the core 4 is set small.
etc. are exemplified.

Preferably, the golf ball 2 satisfies the following formula (3).
(Fp/Fpn) ≤ 0.98 (3)
In other words, the ratio (Fp/Fpn) is 0.98 or less. This golf ball 2 achieves both a soft feel at impact and a firm feel in putting. From this point of view, the ratio (Fp/Fpn) is more preferably 0.96 or less, particularly preferably 0.95 or less. The ratio (Fp/Fpn) is preferably 0.80 or more.

Preferably, the golf ball 2 satisfies the following formula (4).
(Tp/Tpn) ≥ 1.01 (4)
Tp: contact time of the golf ball 2 measured under the second condition Tpn: contact time of the standard ball measured under the second condition In other words, the ratio (Tp/Tpn) is 1.01 or more. This golf ball 2 achieves both a soft feel at impact and a firm feel in putting. From this point of view, the ratio (Tp/Tpn) is more preferably 1.02 or more, particularly preferably 1.03 or more. The ratio (Tp/Tpn) is preferably 1.15 or less.

Preferably, the golf ball 2 satisfies the following formula (5).
(Fp/Fpn)/(Tp/Tpn) ≤ 0.98 (5)
In other words, the ratio ((Fp/Fpn)/(Tp/Tpn)) is 0.98 or less. This golf ball 2 achieves both a soft feel at impact and a firm feel in putting. From this point of view, the ratio ((Fp/Fpn)/(Tp/Tpn)) is more preferably 0.95 or less, particularly preferably 0.92 or less. The ratio ((Fp/Fpn)/(Tp/Tpn)) is preferably 0.75 or more.

Preferably, the golf ball 2 satisfies the following formula (6).
(Tw/Twn) ≥ 1.01 (6)
Tw: contact time of the golf ball 2 measured under the first condition Twn: contact time of the standard ball measured under the first condition In other words, the ratio (Tw/Twn) is 1.01 or more. This golf ball 2 achieves both a soft hitting feel and a biting feel on driver shots. From this point of view, the ratio (Tw/Twn) is particularly preferably 1.02 or more. The ratio (Tw/Twn) is preferably 1.20 or less.

Preferably, golf ball 2 satisfies formula (7).
(Fw/Fwn)/(Tw/Twn) ≤ 0.98 (7)
In other words, the ratio ((Fw/Fwn)/(Tw/Twn)) is 0.98 or less. This golf ball 2 achieves both a soft hitting feel and a biting feel on driver shots. From this point of view, the ratio ((Fw/Fwn)/(Tw/Twn)) is more preferably 0.95 or less, particularly preferably 0.92 or less. The ratio ((Fw/Fwn)/(Tw/Twn)) is preferably 0.75 or more.

The effects of the golf balls according to the examples will be clarified below, but the scope disclosed herein should not be construed to be limited based on the description of the examples.

[Example 1]
100 parts by mass of high cis polybutadiene (JSR company's trade name "BR-60"), 25.3 parts by mass of zinc acrylate, 5.0 parts by mass of zinc oxide, 12.0 parts by mass of barium sulfate, 0.5 parts by mass 3 parts by mass of pentabromodiphenyl disulfide (PBDS) and 0.7 parts by mass of dicumyl peroxide (DCP) were kneaded to obtain a rubber composition. This rubber composition was put into a mold consisting of an upper mold and a lower mold having a hemispherical cavity and heated to obtain a core having a diameter of 39.7 mm.

50 parts by mass of ionomer resin ("Himilan 1605" described above), 50 parts by mass of another ionomer resin ("Himilan AM7329" described above), 4 parts by mass of titanium dioxide and 9 parts by mass of barium sulfate are twin-screw kneaded and extruded. The mixture was kneaded using a machine to obtain a resin composition. The core was put into a mold consisting of an upper mold and a lower mold, each having a hemispherical cavity. The resin composition was coated around the core by injection molding to form an intermediate layer. The thickness of this intermediate layer was 1.0 mm.

A coating composition (trade name “Porin 750LE” manufactured by Shinto Paint Co., Ltd.) having a two-component curing type epoxy resin as a base polymer was prepared. The main liquid of this coating composition contains 30 parts by mass of bisphenol A type epoxy resin and 70 parts by mass of solvent. The curing agent liquid of this coating composition contains 40 parts by weight of modified polyamidoamine, 55 parts by weight of solvent, and 5 parts by weight of titanium dioxide. The mass ratio of the main agent liquid and the curing agent liquid is 1/1. This coating composition was applied to the surface of the intermediate layer with a spray gun and held in an atmosphere of 23° C. for 12 hours to obtain a reinforcing layer. The thickness of this reinforcing layer was 10 μm.

100 parts by mass of thermoplastic polyurethane elastomer (the above-mentioned "Elastollan NY84A"), 2 parts by mass of lubricant (BASF Japan's trade name "Waxmaster VD"), 4 parts by mass of titanium dioxide and 0.2 parts by mass of A light stabilizer (trade name “JF-90” manufactured by Johoku Kagaku Kogyo Co., Ltd.) was kneaded with a twin-screw kneading extruder to obtain a resin composition. Half shells were obtained from this resin composition by compression molding. The two half-shells covered the sphere containing the core, intermediate layer and reinforcing layer. These half shells and spheres were put into a final mold consisting of an upper mold and a lower mold each having a hemispherical cavity and numerous pimples on the cavity surface, and a cover was obtained by compression molding. The thickness of this cover was 0.5 mm. Dimples having a shape that is the inverse of the shape of the pimples were formed on this cover.

A clear paint containing a two-pack curing type polyurethane as a base material was applied around the cover to form an inner paint layer. This inner paint layer was coated with another clear paint based on a two-component curing type polyurethane to form an outer paint layer. Thus, a golf ball of Example 1 having a diameter of about 42.7 mm and a weight of about 45.3 g was obtained.

[Example 2]
A golf ball of Example 2 was obtained in the same manner as in Example 1, except that the specifications of the core, intermediate layer and cover were as shown in Tables 1 and 2 below.

[Comparative Examples 1 and 2]
As Comparative Example 1, a commercially available golf ball was prepared. As Comparative Example 2, another commercially available golf ball was prepared.

[Flight test, W#1]
A driver (trade name “XXIO 11” manufactured by Sumitomo Rubber Industries, shaft product number: MP1100, shaft hardness: S, loft angle: 10.5°) was attached to a golf laboratory swing machine. A golf ball was hit at a head speed of 40 m/sec to measure the spin rate and flight distance. The flight distance is the distance from the hit point to the point where the golf ball comes to rest. Measurement was performed 12 times, and the average value of the obtained data was calculated. Furthermore, based on the average flight distance, the following ratings were given.
A: 215.5 yards or more B: Less than 215.5 yards The results are shown in Table 3 below.

[Flight test, I#7]
A 7-iron club (manufactured by Sumitomo Rubber Industries, Ltd., trade name “XXIO 11”, shaft product number: MP1100, shaft hardness: S, loft angle: 28.0°) was attached to a golf laboratory swing machine. A golf ball was hit at a head speed of 33 m/sec to measure the spin rate and flight distance. Measurement was performed 12 times, and the average value of the obtained data was calculated. Furthermore, based on the average flight distance, the following ratings were given.
A: 148.0 yards or more B: 145.0 yards or more and less than 148.0 yards C: Less than 145.0 yards These results are shown in Table 3 below.

[Feel at impact, W#1]
A golf ball was hit by a tester with a driver and scored according to the following criteria.
0 points: Hard 2 points: Slightly hard 5 points: Normal 8 points: Slightly soft 10 points: Soft The sum of the scores given by 50 testers was calculated, and the following ratings were given.
A: 310 points or more B: 300 points or more and less than 310 points C: Less than 300 points These results are shown in Table 3 below.

[Feel at impact, putter]
A golf ball was hit by a tester with a putter and scored according to the following criteria.
0 points: Hard 2 points: Slightly hard 5 points: Normal 8 points: Slightly soft 10 points: Soft The sum of the scores given by 50 testers was calculated, and the following ratings were given.
A: 330 points or more B: 300 points or more and less than 330 points C: Less than 300 points These results are shown in Table 3 below.

As shown in Table 3, the golf balls of each example had excellent flight performance on driver shots, flight performance on middle iron shots, shot feel on driver shots, and shot feel on putting. Excellent. This evaluation result clearly shows the superiority of this golf ball.

[Disclosure items]
Each of the following items is a disclosure of a preferred embodiment.

[Item 1]
comprising a core, an intermediate layer positioned outside the core, and a cover positioned outside the intermediate layer,
A golf ball that satisfies the following formulas (1) and (2).
(Fw/Fwn) ≤ 0.98 (1)
(Fw/Fwn) ² / (Fp/Fpn) ≤ 0.98 (2)
(In these equations, Fw represents the maximum normal force of the golf ball measured under the first condition, Fwn represents the maximum normal force of the standard ball measured under this first condition, and Fp represents the second Fpn represents the maximum vertical force of the golf ball measured under this condition, and Fpn represents the maximum vertical force of the standard ball measured under this second condition.)

[Item 2]
The golf ball according to item 1, which satisfies the following formula (3).
(Fp/Fpn) ≤ 0.98 (3)

[Item 3]
The golf ball according to item 1 or 2, which satisfies the following formula (4).
(Tp/Tpn) ≥ 1.01 (4)
(In this formula, Tp represents the contact time of the golf ball measured under the second condition, and Tpn represents the contact time of the standard ball measured under the second condition.)

[Item 4]
3. The golf ball according to item 3, which satisfies the following formula (5).
(Fp/Fpn)/(Tp/Tpn) ≤ 0.98 (5)

[Item 5]
5. The golf ball according to any one of items 1 to 4, which satisfies the following formula (6).
(Tw/Twn) ≥ 1.01 (6)
(In this formula, Tw represents the contact time of the golf ball measured under the first condition, and Twn represents the contact time of the standard ball measured under the first condition.)

[Item 6]
5. The golf ball according to item 5, which satisfies the following formula (7).
(Fw/Fwn)/(Tw/Twn) ≤ 0.98 (7)

[Item 7]
7. The golf ball according to any one of items 1 to 6, wherein the amount of compressive deformation CD measured under conditions of an initial load of 98 N and a final load of 1274 N is 3.00 mm or more.

[Item 8]
8. Any one of items 1 to 7, wherein a surface hardness H2s (Shore C) of the intermediate layer is greater than a surface hardness H1s (Shore C) of the core and greater than a surface hardness H3s (Shore C) of the cover. A golf ball as described.

[Item 9]
9. The golf ball according to any one of items 1 to 8, wherein the core has a difference (H1s - H1o) between a surface hardness H1s (Shore C) and a center hardness H1o (Shore C) of 14 or more.

[Item 10]
10. The golf ball according to any one of items 1 to 9, wherein the ratio of the sum (T2+T3) of the thickness T2 of the intermediate layer and the thickness T3 of the cover to the diameter D1 of the core is 0.042 or less. .

[Item 11]
11. The golf ball according to any one of items 1 to 10, wherein a ratio (H2/H3) of hardness H2 (Shore D) of the intermediate layer to hardness H3 (Shore D) of the cover is 1.80 or more.

[Item 12]
further comprising one or more paint layers positioned outside the cover;
12. The golf ball according to any one of items 1 to 11, wherein the depth of indentation of the outermost paint layer under a load of 30 mgf is 300 nm or more and 3000 nm or less.

The aforementioned golf balls are suitable for golf course play, driving range practice, and the like.

2 golf ball 4 core 6 intermediate layer 8 cover 10 inner paint layer 12 outer paint layer 14 dimple 16 land

Claims (12)

comprising a core, an intermediate layer positioned outside the core, and a cover positioned outside the intermediate layer,
A golf ball that satisfies the following formulas (1) and (2).
(Fw/Fwn) ≤ 0.98 (1)
(Fw/Fwn) ² / (Fp/Fpn) ≤ 0.98 (2)
(In these equations, Fw represents the maximum normal force of the golf ball measured under the first condition, Fwn represents the maximum normal force of the standard ball measured under this first condition, and Fp represents the second Fpn represents the maximum vertical force of the golf ball measured under this condition, and Fpn represents the maximum vertical force of the standard ball measured under this second condition.) 2. The golf ball of claim 1, which satisfies the following formula (3).
(Fp/Fpn) ≤ 0.98 (3) 3. The golf ball according to claim 1, which satisfies the following formula (4).
(Tp/Tpn) ≥ 1.01 (4)
(In this formula, Tp represents the contact time of the golf ball measured under the second condition, and Tpn represents the contact time of the standard ball measured under the second condition.) 4. The golf ball of claim 3, which satisfies the following formula (5).
(Fp/Fpn)/(Tp/Tpn) ≤ 0.98 (5) 5. The golf ball according to any one of claims 1 to 4, which satisfies the following formula (6).
(Tw/Twn) ≥ 1.01 (6)
(In this formula, Tw represents the contact time of the golf ball measured under the first condition, and Twn represents the contact time of the standard ball measured under the first condition.) 6. The golf ball of claim 5, which satisfies the following formula (7).
(Fw/Fwn)/(Tw/Twn) ≤ 0.98 (7) 7. The golf ball according to any one of claims 1 to 6, wherein the amount of compressive deformation CD measured under conditions of an initial load of 98 N and a final load of 1275 N is 3.00 mm or more. 8. The surface hardness H2s (Shore C) of the intermediate layer is higher than the surface hardness H1s (Shore C) of the core and higher than the surface hardness H3s (Shore C) of the cover. The golf ball described in . 9. The golf ball according to claim 1, wherein the core has a difference (H1s-H1o) between a surface hardness H1s (Shore C) and a center hardness H1o (Shore C) of 14 or more. The golf according to any one of claims 1 to 9, wherein the ratio of the sum of the thickness T2 of the intermediate layer and the thickness T3 of the cover (T2 + T3) to the diameter D1 of the core is 0.042 or less. ball. 11. The golf ball of claim 1, wherein a ratio (H2/H3) of hardness H2 (Shore D) of the intermediate layer to hardness H3 (Shore D) of the cover is 1.80 or more. . further comprising one or more paint layers positioned outside the cover;
12. The golf ball according to any one of claims 1 to 11, wherein the depth of indentation of the outermost paint layer at a load of 30 mgf is 300 nm or more and 3000 nm or less.

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