JP2015126773A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball showing a large carry on driver shots, an excellent contamination resistant and excellent ball-hitting feeling.SOLUTION: A golf ball comprises a golf ball body including a core 21 and a cover 22, and a coating film 23. A base material resin of the coating film 23 is a polyurethane obtained by reacting a polyol and a polyisocyanate. The polyol includes an urethane polyol containing a polyether diol having a number average molecular weight of 800-3000 as a constituent. A 10% modulus of the coating film 23 is not more than 100 kgf/cm. The 10% modulus of the coating film 23(kgf/cm)(Y) and a molar ratio (NCO/OH)(X) of an OH group of the polyol composition and a NCO group of the polyisocyanate composition satisfies the relation of following Formula (1). A 10% modulus of the cover 22 is not less than 120 kgf/cm. Y≤200×X-75(1)

Description

  The present invention relates to a technique for improving the flight distance and stain resistance of a golf ball.

  A coating film is provided on the surface of the golf ball body. It has been proposed to improve the properties of golf balls by improving the coating.

Patent Document 1 includes a core, a cover located outside the core, and a paint layer located outside the cover, and the Shore D hardness of the cover is 61 or less, and the Martens of the paint layer. A golf ball having a hardness of 2.0 mgf / μm ² or less is disclosed. The golf ball of Patent Document 1 is excellent in spin performance, spin speed stability, and paint layer durability.

Patent Document 2 discloses a golf ball having a golf ball body and a coating film provided on the surface of the golf ball body, the coating film having a Martens hardness of 2.0 mgf / μm ² or less and a 10% modulus. A golf ball having a ratio of 50% modulus to 50% modulus (50% modulus / 10% modulus) of 1.6 or more is disclosed. The golf ball of Patent Document 2 has a high spin rate for approach shots under wet conditions and rough conditions.

  In Patent Document 3, a golf ball having a golf ball body and a coating film provided on the surface of the golf ball body, the friction coefficient calculated using a contact force tester is 0.35 or more and 0.60. A golf ball characterized by the following is disclosed.

JP 2011-67595 A JP 2011-217820 A JP 2013-176530 A

  In the prior art, the feel at impact is improved by softening the coating film. Here, as a method of softening the coating film, a method of reducing the use amount of the curing agent and reducing the degree of crosslinking can be mentioned. However, when the degree of crosslinking in the coating film is lowered, there is a problem that the stain resistance of the coating film is lowered. In addition, when the coating film is softened, the flight performance of the golf ball tends to decrease. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a golf ball having a great flight distance on a driver shot and excellent in contamination resistance and feel at impact.

The golf ball of the present invention has a golf ball main body having a core and a cover covering the core, and a coating film provided on the surface of the golf ball main body, and the base resin constituting the coating film is a polyol. A polyurethane obtained by reacting a composition with a polyisocyanate composition, wherein the polyol composition contains a urethane polyol containing a polyether diol having a number average molecular weight of 800 to 3000 as a constituent component, and the coating film 10% modulus is 100 kgf / cm ² or less, 10% modulus (kgf / cm ² ) of the coating film, hydroxyl group (OH group) of the polyol composition, and isocyanate group (NCO of the polyisocyanate composition). Group) (NCO / OH) satisfies the relationship of the following formula (1), and 10% Las, characterized in that it is 120 kgf / cm ² or more.
Y ≦ 200 × X−75 (1)
[Wherein Y is the 10% modulus (kgf / cm ² ) of the coating film, and X is the molar ratio (NCO group) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition. / OH). ]

The golf ball of the present invention contains a urethane polyol containing a polyether diol having a number average molecular weight of 800 to 3000 as a constituent component as a polyol component of the coating film. By using such a urethane polyol, the obtained coating film becomes soft. Further, the 10% modulus (kgf / cm ² ) of the coating film and the molar ratio (NCO / OH) of the OH group of the polyol composition to the NCO group of the polyisocyanate composition constituting the coating film are represented by the formula (1). Satisfy the relationship. That is, even if the molar ratio (NCO / OH) is increased, the flexibility of the coating film is high. Furthermore, the 10% modulus of the cover is 120 kgf / cm ² or more, and the cover is relatively hard. With these configurations, the golf ball has a great flight distance on driver shots, and is excellent in contamination resistance and feel at impact.

  According to the present invention, it is possible to obtain a golf ball that has a great flight distance on driver shots and is excellent in contamination resistance and feel at impact.

1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention. Schematic of an example of a contact force tester used in the present invention. The expanded partial sectional view of the collision board of a contact force test machine. The graph which shows an example of Ft (t), Fn (t), and M (t). Sectional drawing of the groove shape of the surface material of a contact force tester. The graph which shows an example of Ft (t), Fn (t), and M (t). The schematic diagram which shows an example of the coating form using an air gun.

  The golf ball of the present invention has a golf ball body and a coating film provided on the surface of the golf ball body. The base resin constituting the coating film is formed of polyurethane formed by reacting a polyol composition and a polyisocyanate composition.

  Hereinafter, the polyol composition and polyisocyanate composition constituting the coating film will be described. The polyol composition contains a urethane polyol containing a polyether diol having a number average molecular weight of 800 to 3000 as a constituent component. By using such a urethane polyol, the obtained coating film becomes soft. The urethane polyol is a compound having a plurality of urethane bonds in the molecule and having two or more hydroxyl groups in one molecule. Examples of the urethane polyol include a urethane prepolymer obtained by reacting a polyol and a polyisocyanate under conditions such that the hydroxyl group of the polyol is excessive with respect to the isocyanate group of the polyisocyanate.

  Examples of the polyether diol that can constitute the urethane polyol include polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol. Among these, polyoxytetramethylene glycol is preferable.

  The polyether diol has a number average molecular weight of 800 or more, preferably 900 or more, more preferably 1000 or more, and 3000 or less, preferably 2000 or less, more preferably 1500 or less. When the number average molecular weight of the polyether diol is 800 or more, the distance between the crosslinking points in the coating film becomes long and the coating film becomes soft. If the said number average molecular weight is 3000 or less, the distance between the crosslinking points in a coating film will not become long too much, but the stain resistance of a coating film will become favorable. The number average molecular weight of the polyol component is determined by, for example, gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and a column for an organic solvent GPC as a column (for example, “Shodex (registered trademark) manufactured by Showa Denko KK Trademark) KF series "etc.).

  The urethane polyol may contain a low molecular weight polyol having a molecular weight of less than 500 other than the polyether diol as a polyol component. 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; glycerin and trimethylol. Examples include triols such as propane and hexanetriol. The low molecular weight polyols may be used alone or in admixture of two or more.

  The urethane polyol preferably contains a triol component and a diol component as the polyol component. As the triol component, trimethylolpropane is preferable. The mixing ratio of the triol component and the diol component (triol component / diol component) is, by mass ratio, preferably 0.2 or more, more preferably 0.5 or more, preferably 6.0 or less, and more preferably 5.0 or less. preferable.

The polyisocyanate component that can constitute the urethane polyol is not particularly limited as long as it has two or more isocyanate groups. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate And 2,6-toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3′-vitrylene-4,4′-diisocyanate (TODI) ), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), aromatic polyisocyanates such as para-phenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate _{(H 12} DI), hydrogenated xylylene diisocyanate _(H 6 XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), include cycloaliphatic polyisocyanates or aliphatic polyisocyanates such as norbornene diisocyanate (NBDI). These polyisocyanates may be used alone or in combination of two or more.

  In the urethane polyol, the content of the polyether diol having the number average molecular weight of 800 to 3000 is preferably 70% by mass or more, more preferably 72% by mass or more, and further preferably 75% by mass or more. The polyether diol having a number average molecular weight of 800 to 3000 forms a soft segment in the coating film. Therefore, when the content of the polyether diol is 70% by mass or more, the feel at impact of the obtained golf ball is further improved.

  The urethane polyol has a weight average molecular weight of preferably 5000 or more, more preferably 5300 or more, further preferably 5500 or more, preferably 20000 or less, more preferably 18000 or less, and further preferably 16000 or less. When the weight average molecular weight of the urethane polyol is 5000 or more, the distance between the crosslinking points in the coating film becomes long, the coating film becomes soft, and the shot feeling is further improved. If the said weight average molecular weight is 20000 or less, the distance between the crosslinking points in a coating film will not become long too much, but the stain resistance of a coating film will become favorable.

  The hydroxyl value of the urethane polyol is preferably 10 mgKOH / g or more, more preferably 15 mgKOH / g or more, still more preferably 20 mgKOH / g or more, preferably 200 mgKOH / g or less, more preferably 190 mgKOH / g or less, still more preferably. Is 180 mgKOH / g or less.

  The polyol composition may contain a polyol compound other than the urethane polyol as the polyol compound. Examples of the polyol compound include a low molecular weight polyol having a molecular weight of less than 500 and a high molecular weight polyol having an average molecular weight of 500 or more. 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; glycerin and trimethylol. Examples include triols such as propane and hexanetriol. Examples of the high molecular weight polyol include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); polyethylene adipate (PEA), polybutylene adipate (PBA) , A condensed polyester polyol such as polyhexamethylene adipate (PHMA); a lactone polyester polyol such as poly-ε-caprolactone (PCL); a polycarbonate polyol such as polyhexamethylene carbonate; and an acrylic polyol. The other polyol compounds may be used alone or in admixture of two or more.

  60 mass% or more is preferable, as for the content rate of the said urethane polyol in the polyol compound which the said polyol composition contains, More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more. It is also preferable that the polyol composition contains only the urethane polyol as a polyol compound.

  The hydroxyl value of the polyol contained in the polyol composition is preferably 10 mgKOH / g or more, more preferably 15 mgKOH / g or more, still more preferably 20 mgKOH / g or more, preferably 400 mgKOH / g or less, preferably 300 mgKOH / g. Hereinafter, it is more preferably 200 mgKOH / g or less, further preferably 170 mgKOH / g or less, and particularly preferably 160 mgKOH / g or less. This is because when the hydroxyl value of the polyol component is within the above range, the adhesion of the coating film to the golf ball body is improved. In the present invention, the hydroxyl value can be measured, for example, by an acetylation method according to JIS K1557-1.

  Specific examples of the polyol compound include, for example, 121B manufactured by Waku Paint Co., Ltd., Nippon Run Industrial Co., Ltd., Nippon Runa 800, Nippon Runa 1100, DIC Co., Ltd. Burnock D6-627, Burnock D8-436, Burnock D8-973, Burnock 11- 408, demosphen 650MPA, demosphen 670, demosphen 1150, demosfen A160X, Sumika Bayer Urethane Co., Ltd., Harimacron 2000, Hariacron 8500H, Harima Chemicals, etc.

  Next, the polyisocyanate composition will be described. The polyisocyanate composition contains one or more polyisocyanate compounds. Examples of the polyisocyanate compound include compounds having at least two isocyanate groups.

Examples of the polyisocyanate compound 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′-vitrylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), paraphenylene diisocyanate (PPDI) aromatic diisocyanates such as 4,4'-dicyclohexylmethane diisocyanate _(H 12 MDI), hydrogenated xylylene diisocyanate _(H 6 XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI) and the like; and triisocyanates of these diisocyanates such as allophanates, burettes, isocyanurates and adducts; Can be mentioned. In the present invention, it is preferable to use two or more polyisocyanates as the polyisocyanate.

  The allophanate body is, for example, a triisocyanate obtained by further reacting a diisocyanate with a urethane bond formed by reacting a diisocyanate and a low molecular weight diol. An adduct is triisocyanate obtained by reacting diisocyanate with a low molecular weight triol such as trimethylolpropane or glycerin. The burette body is, for example, triisocyanate having a burette bond represented by the following formula (1). The isocyanurate form of diisocyanate is, for example, a triisocyanate represented by the following formula (2).

式（１）、（２）中、Ｒは、ジイソシアネートからイソシアネート基を除いた残基を表わす。

In formulas (1) and (2), R represents a residue obtained by removing an isocyanate group from diisocyanate.

  As the triisocyanate, hexamethylene diisocyanate isocyanurate, hexamethylene diisocyanate burette, and isophorone diisocyanate isocyanurate are preferable. In particular, when a burette modified product of hexamethylene diisocyanate and an isocyanurate modified product are used in combination, the mixing ratio (burette modified product / isocyanurate modified product) is preferably 20/40 to 40/20 in terms of mass ratio. 25/35 to 35/25 is more preferable.

  In the present invention, the polyisocyanate composition preferably contains a triisocyanate compound. As for the content rate of the triisocyanate compound in the polyisocyanate which the said polyisocyanate composition contains, 50 mass% or more is preferable, More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more. Most preferably, the polyisocyanate composition contains only a triisocyanate compound as a polyisocyanate compound.

  The isocyanate group amount (NCO%) of the polyisocyanate contained in the polyisocyanate composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, and 45% by mass or less. Preferably, 40 mass% or less is more preferable, and 35 mass% or less is further more preferable. In addition, the isocyanate group amount (NCO%) of the polyisocyanate can be expressed by 100 × [number of moles of isocyanate groups in the polyisocyanate × 42 (molecular weight of NCO)] / total mass of polyisocyanate (g).

  Specific examples of the polyisocyanate include Burnock D-800, Burnock DN-950, Burnock DN-955, Death Module N75MPA / X, Death Module N3300, Death Module L75 (C), manufactured by Sumika Bayer Urethane. Name Sumijour E21-1, Coronate HX, Coronate HK from Nippon Polyurethane Industry Co., Ltd., Duranate 24A-100, Duranate 21S-75E, Duranate TPA-100, Duranate TKA-100, Vestana T1890 from Degussa, etc. Can do.

  In the reaction between the polyol composition and the polyisocyanate composition, the molar ratio (NCO group / OH group) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition is 0. More than 5 is preferable, more preferably 0.55 or more, and still more preferably 0.60 or more. When the molar ratio (NCO group / OH group) exceeds 0.5, the crosslink density increases and the resulting coating film has better stain resistance. On the other hand, if the molar ratio (NCO group / OH group) becomes too large, the amount of isocyanate groups becomes excessive, the resulting coating film becomes hard and brittle, and the appearance also deteriorates. Therefore, the molar ratio (NCO group / OH group) is preferably 1.20 or less, more preferably 1.15 or less, and further preferably 1.10 or less. The reason why the appearance of the resulting coating film deteriorates when the amount of isocyanate groups in the paint is excessive is that when the amount of isocyanate groups is excessive, the reaction between moisture in the air and isocyanate groups increases, and a large amount of carbon dioxide gas is present. This is thought to occur.

The 10% modulus of the coating film is 100 kgf / cm ² (9.8 MPa) or less, preferably 90 kgf / cm ² (8.8 MPa) or less, more preferably 80 kgf / cm ² (7.8 MPa) or less. If the 10% modulus is 100 kgf / cm ² or less, the coating film is soft and the feel at impact is good. The lower limit of the 10% modulus of the coating film is not particularly limited, but is preferably 5 kgf / cm ² (0.49 MPa), more preferably 10 kgf / cm ² (0.98 MPa). This is because if the 10% modulus is too small, it becomes too soft, a tucking feeling remains, and the feeling becomes worse.

The coating film has a 10% modulus (kgf / cm ² ) and a molar ratio (NCO / OH) of a hydroxyl group (OH group) of the polyol composition to an isocyanate group (NCO group) of the polyisocyanate composition. The relationship of the following formula (1) is satisfied. Those satisfying the following formula (1) can maintain the flexibility of the coating film even when the molar ratio (NCO / OH) is increased, and are excellent in stain resistance.
Y ≦ 200 × X−75 (1)
[Wherein Y is the 10% modulus (kgf / cm ² ) of the coating film, and X is the molar ratio (NCO group) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition. / OH). ]

  The golf ball coating film of the present invention is preferably formed from a paint containing a polyol composition and a polyisocyanate composition. Examples of the paint include a so-called two-component curable paint having a polyol as a main component and a polyisocyanate as a curing agent. The paint may be either a water-based paint using water as a main dispersion medium or a solvent-based paint using an organic solvent as a dispersion medium. In the case of solvent-based paints, 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, ethyl acetate and the like.

  The paint is generally a golf ball paint such as a filler, an ultraviolet absorber, an antioxidant, a light stabilizer, a fluorescent brightener, an antiblocking agent, a leveling agent, a slip agent, and a viscosity modifier. You may contain the additive which may be contained in.

  Next, a method for applying the curable paint of the present invention will be described. The application method of the curable coating material is not particularly limited, and a known method can be employed, and examples thereof include spray coating and electrostatic coating.

  In the case of spray painting using an air gun, the polyol composition and the polyisocyanate composition are supplied by respective pumps, mixed continuously by a line mixer arranged immediately before the air gun, and the resulting mixture is sprayed. The coating may be performed, or the polyol and the polyisocyanate may be sprayed separately using an air spray system equipped with a mixing ratio control mechanism. The coating may be performed by spraying once or by multiple coatings.

  The curable paint applied to the golf ball main body can form a coating film by drying at a temperature of 30 ° C. to 70 ° C. for 1 hour to 24 hours, for example.

  Although the film thickness of the coating film after drying is not specifically limited, 5 micrometers or more are preferable, 6 micrometers or more are more preferable, 10 micrometers or more are further more preferable, and 15 micrometers or more are especially preferable. When the film thickness is less than 5 μm, the coating tends to be worn away by continuous use. Moreover, it is because a shot feeling becomes favorable by increasing the film thickness. Moreover, the film thickness of the coating film is preferably 50 μm or less, more preferably 45 μm or less, and further preferably 40 μm or less. If the film thickness is larger than 50 μm, the dimple effect may be reduced and the flight performance of the golf ball may be reduced. The film thickness of a coating film can measure the cross section of a golf ball, for example using a microscope (VHX-1000 by Keyence Corporation). In addition, when the coating material is repeatedly applied several times, it is preferable that the thickness of the formed coating film is in the above range.

  The golf ball of the present invention includes a golf ball main body having a core and a cover covering the core, and a coating film provided on the surface of the golf ball main body. The structure of the golf ball body is not particularly limited as long as it has a core and a cover that covers the core, and a multi-piece golf ball that is more than a two-piece golf ball, a three-piece golf ball, a four-piece golf ball, and a five-piece golf ball. Alternatively, a thread wound golf ball may be used. This is because the present invention can be preferably applied in any case.

  FIG. 1 is a partially cutaway sectional view showing a golf ball 20 according to an embodiment of the present invention. The golf ball 20 includes a spherical core 21, a cover 22 that covers the spherical core 21, and a coating film 23 provided on the surface of the cover 22. A large number of dimples 24 are formed on the surface of the cover 22. Of the surface of the cover 22, a portion other than the dimples 24 is a land 25.

The cover has a 10% modulus of 120 kgf / cm ² (11.8 MPa) or more, preferably 123 kgf / cm ² (12.1 MPa) or more, more preferably 126 kgf / cm ² (12.4 MPa) or more. If the 10% modulus is 120 kgf / cm ² or more, the cover becomes hard and the flight distance of the driver shot increases. The upper limit of the 10% modulus of the cover is not particularly ^limited, but is preferably ^{280kgf / cm 2 (27.5MPa),} 275kgf / cm 2 (27.0MPa) is more preferable. This is because if the 10% modulus is too large, it becomes too hard and the feel at impact is poor.

  The hardness of the cover is Shore D hardness, preferably more than 60, more preferably 62 or more, further preferably 64 or more, and particularly preferably 66 or more. This is because if the cover has a Shore D hardness of more than 60, the flight distance of the driver shot is further increased. Although the upper limit of the cover hardness is not particularly limited, the Shore D hardness is preferably 75, more preferably 73, and even more preferably 71. The cover hardness is a slab hardness measured by molding a cover composition for forming a cover into a sheet shape.

  The thickness of the cover is preferably 0.5 mm or more, more preferably 0.6 mm or more, further preferably 0.7 mm or more, preferably 3.0 mm or less, more preferably 2.7 mm or less, and still more preferably. It is 2.4 mm or less. If the cover has a thickness of 0.5 mm or more, the flight distance of the golf ball will be better, and if it is 3.0 mm or less, the feel of the golf ball will be better.

  The cover material constituting the cover is not particularly limited, and examples thereof include ionomer resins, polyurethanes, polyamides, polyesters and polystyrenes, and ionomer resins and polyamides are preferable.

  The polyurethane may be either a so-called thermoplastic polyurethane or a thermosetting polyurethane. The thermoplastic polyurethane is a polyurethane that exhibits plasticity when heated, and generally means a polyurethane having a linear structure that has been polymerized to some extent. On the other hand, a thermosetting polyurethane (two-component curable polyurethane) is obtained by reacting a low molecular weight urethane prepolymer with a curing agent (chain extender) to increase the molecular weight when molding a cover. Polyurethane. The thermosetting polyurethane includes a polyurethane having a linear structure and a polyurethane having a three-dimensional cross-linking structure by controlling the number of functional groups of the prepolymer and the curing agent (chain extender) to be used. The polyurethane is preferably a thermoplastic elastomer.

  Examples of the ionomer resin include a resin obtained by neutralizing at least a part of a carboxyl group in a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms with a metal ion. And a ternary copolymer of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester, wherein at least a part of the carboxyl group is neutralized with a metal ion, or And mixtures thereof. The olefin is preferably an olefin having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, butene, pentene, hexene, heptene, octene and the like, and ethylene is particularly preferable. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid. Acrylic acid or methacrylic acid is particularly preferable. Examples of the α, β-unsaturated carboxylic acid ester include methyl, ethyl, propyl, n-butyl, isobutyl ester and the like such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, and particularly acrylic acid ester. Or a methacrylic acid ester is preferable. Among these, as the ionomer resin, a metal ion neutralized product of an ethylene- (meth) acrylic acid binary copolymer, an ethylene- (meth) acrylic acid- (meth) acrylic acid ester terpolymer, A metal ion neutralized product is preferred.

  A specific example of the cover material is exemplified by a trade name, which is commercially available from Mitsui DuPont Polychemical Co., Ltd. under the trade name “Himilan (registered trademark)”, a product from Ionomer Resin, BASF Japan Ltd. Thermoplastic polyurethane elastomer marketed under the name "Elastollan (registered trademark)", from Arkema Co., Ltd. Thermoplastic polyamide elastomer marketed under the brand name "Pebax (registered trademark)", from Toray DuPont Co., Ltd. The thermoplastic polyester elastomer marketed under the trade name “Hytrel” (registered trademark), the thermoplastic styrene elastomer marketed under the trade name “Lavalon” from Mitsubishi Chemical Corporation, or the product name “Primalloy” Examples include commercially available thermoplastic polyester elastomers. Kill. You may use the said cover material individually or in mixture of 2 or more types.

  In addition to the resin component described above, the cover includes a pigment component such as a white pigment (for example, titanium oxide), a blue pigment, and a red pigment, a specific gravity adjuster such as calcium carbonate and barium sulfate, a dispersant, an anti-aging agent, and an ultraviolet absorber. An agent, a light stabilizer, a fluorescent material, a fluorescent whitening agent, or the like may be contained as long as the performance of the cover is not impaired.

  Although the aspect which shape | molds a cover using the composition for a cover is not specifically limited, the aspect which directly inject-molds the composition for a cover on a core, or shape | molds a hollow shell-like shell from a composition for a cover, and a core And a method of compression molding by coating with a plurality of shells (preferably a method of molding a hollow shell-shaped half shell from a cover composition and coating a core with two half shells) Can do. The golf ball body in which the cover is molded is preferably taken out from the mold and subjected to surface treatment such as deburring, washing, and sandblasting as necessary. Moreover, a mark can be formed if desired.

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

  In the present invention, the ratio of the total area of all the dimples to the surface area of the phantom sphere is called an occupation ratio. A virtual sphere is a golf ball (sphere) when no dimples are present. In the golf ball of the present invention, the dimple occupancy is preferably 60% or more, more preferably 63% or more, still more preferably 66% or more, preferably 90% or less, more preferably 87% or less, and 84% or less. Further preferred. If the occupation ratio becomes too high, the contribution of the coating film to the friction coefficient becomes small. Further, if the occupation ratio is too small, the flight performance is deteriorated.

The area of the dimple is the area of the region surrounded by the contour line when the center of the golf ball is viewed from infinity. In the case of a circular dimple, the area S is calculated by the following mathematical formula.
S = (Di / 2) ² · π (Di: dimple diameter)

  The diameter of the golf ball is preferably 40 mm to 45 mm. From the viewpoint of satisfying the standards of the US Golf Association (USGA), the diameter is preferably 42.67 mm or more. In light of air resistance, the diameter is preferably equal to or less than 44 mm, and more preferably equal to or less than 42.80 mm. The weight of the golf ball is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining a large inertia, the mass is preferably 44 g or more, and more preferably 45.00 g or more. From the viewpoint that the USGA standard is satisfied, the mass is preferably equal to or less than 45.93 g.

  Next, the core of the golf ball body will be described. A known rubber composition (hereinafter sometimes simply referred to as “core rubber composition”) may be used for the core. For example, a rubber composition containing a base rubber, a co-crosslinking agent, and a crosslinking initiator. Can be formed by hot pressing.

  As the base rubber, it is particularly preferable to use a high-cis polybutadiene having a cis bond advantageous for rebound of 40% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more. 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 a metal salt of acrylic acid or a metal salt of methacrylic acid. As the metal of the metal salt, zinc, magnesium, calcium, aluminum, and sodium are preferable, and zinc is more preferable. The amount of the co-crosslinking agent used is preferably 20 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base rubber. As the crosslinking initiator, an organic peroxide is preferably used. Specifically, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butylperoxy) Organic peroxides such as hexane and di-t-butyl peroxide can be mentioned, and among them, dicumyl peroxide is preferably used. The amount of the crosslinking initiator is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 3 parts by mass or less, more preferably 100 parts by mass of the base rubber. 2 parts by mass or less.

  The rubber composition for a core may further contain an organic sulfur compound. As the organic sulfur compound, diphenyl disulfides, thiophenols, and thionaphthols can be preferably used. The compounding amount of the organic sulfur compound is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 5.0 parts by mass or less with respect to 100 parts by mass of the base rubber. Preferably it is 3.0 mass parts or less. The core rubber composition may further contain a carboxylic acid and / or a salt thereof. The carboxylic acid and / or salt thereof is preferably a carboxylic acid having 1 to 30 carbon atoms and / or a salt thereof. The compounding quantity of carboxylic acid and / or its salt is 1 to 40 mass parts with respect to 100 mass parts of base rubber.

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

  When the golf ball of the present invention is a multi-piece golf ball of three-piece, four-piece golf ball, five-piece golf ball or more, as an intermediate layer provided between the core and the outermost layer cover, for example, polyurethane resin, Examples include thermoplastic resins such as ionomer resins, polyamide resins, and polyethylene; thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyurethane elastomers, and polyester elastomers; and cured products of rubber compositions. Here, examples of the ionomer resin include those obtained by neutralizing at least a part of carboxyl groups in a copolymer of ethylene and α, β-unsaturated carboxylic acid with metal ions, or ethylene and α, β-unsaturated. What neutralized at least one part of the carboxyl group in the ternary copolymer of saturated carboxylic acid and (alpha), (beta)-unsaturated carboxylic acid ester with a metal ion is mentioned. The intermediate layer may further contain a specific gravity adjusting agent such as barium sulfate or tungsten, an antiaging agent, or a pigment. The intermediate layer may be referred to as an inner cover layer or an outer layer core depending on the configuration of the golf ball.

  The golf ball of the present invention is a golf ball having a golf ball main body and a coating film provided on the surface of the golf ball main body, and the friction coefficient calculated using a contact force tester is 0.35 or more,. It is preferable that it is 60 or less.

In the present invention, the friction coefficient calculated using the contact force tester is the golf ball when the golf ball collides with the collision plate installed at a predetermined angle with respect to the flight direction of the golf ball. And the friction coefficient of the collision plate. A contact force tester simultaneously calculates a contact force time function Fn (t) in a direction perpendicular to the collision plate and a contact force time function Ft (t) in a direction parallel to the collision plate, and is defined by the following equation: The maximum value of the time function M (t) of the ratio between the two is obtained as a friction coefficient.
M (t) = Ft (t) / Fn (t)

  The calculation method of the friction coefficient in this invention is demonstrated based on FIGS. FIG. 2 is a contact force tester for measuring the friction coefficient. FIG. 3 is an enlarged cross-sectional view of the collision plate 4 on which the golf ball collides.

  The contact force tester 1 can artificially create a state in which a golf ball is hit with a club face and measure various forces at that time. The contact force testing machine 1 includes a launching device 5 that can launch a golf ball 2 vertically upward, for example, and a collision surface having a striking surface 3 that collides with the golf ball 2 by being positioned above the launched golf ball 2. Plate 4.

  Since the distance between the launching device 5 and the striking surface 3 is relatively small, the initial speed of the golf ball 2 corresponds to the collision speed. The collision speed corresponds to the head speed of the club head in an actual golf swing. In view of such a point, the collision speed between the golf ball 2 and the striking surface 3 can be set, for example, within a range of about 10 m / s to 50 m / s. In the present invention, the initial speed is set to 9 m / sec in consideration of the head speed of the approach shot.

  A target value of the initial velocity of the golf ball 2 is set by the volume of the controller 6 or the like. Further, the controller 6 calculates the actual measured value of the initial velocity of the golf ball 2 using the distance between the first sensor S1 and the second sensor S2 provided in the launching device 5 and the time difference for blocking the sensor. And can be output to a computer apparatus PC or the like.

  FIG. 3 shows an enlarged partial sectional view of the collision plate 4. The collision plate 4 can tilt the striking surface 3 at an arbitrary angle α with respect to the launch direction (flight direction) of the golf ball 2. In the present invention, an angle θ obtained by subtracting the angle α from 90 degrees is set as a collision angle. This collision angle θ corresponds to the loft angle of a club face (not shown) in an actual swing. The collision angle θ is set to a plurality of values (for example, 15 °, 20 °, 35 °, etc.) in consideration of the loft angle of the golf club from the range of 10 ° to 90 °, for example. The contact force described later can be measured. In the present invention, in order to reproduce the spin amount of the approach shot, the collision angle θ is set to 55 °.

  The collision plate 4 includes a base plate 4a made of, for example, a metal plate, a surface layer plate 4c constituting the striking surface 3, and a pressure sensor 4b sandwiched therebetween, which are mutually connected by bolts 4d. Affixed together.

  The base plate 4a has only to have predetermined strength and rigidity, and the material is not particularly limited, but steel is preferably used. The thickness of the base plate 4a is preferably 5.0 mm to 20.0 mm. The model number of the main bolt 4d according to the JIS standard is, for example, M10.

  For example, a three-component force sensor is preferably used as the pressure sensor 4b. Such a sensor uses at least a normal force Fn in a direction perpendicular to the striking surface 3 and a shear force Ft in a direction parallel to the striking surface 3 (from the sole side to the crown side in the club face) as time series data. It can be measured. The force is measured by connecting a charge amplifier or the like to the pressure sensor 4b.

  Various products can be used for the pressure sensor 4b. For example, a three-component force sensor (model 9067) manufactured by Kistler is used. This sensor can measure force components in parallel, Y and perpendicular directions. Although not shown, the pressure is measured by connecting a charge amplifier (Kistler Model 5011B) to the pressure sensor 4b. A through hole is formed in the center of the pressure sensor 4b. The main bolt 4d is inserted into the through hole, and the pressure sensor 4b is fixedly integrated with the base plate 4a.

  The surface layer plate 4c is composed of a main body 4c1 and a surface layer material 4c2 having an area sufficient to appear on the striking surface 3 and collide with the golf ball 2 by being arranged on the outer side. These are fixed detachably using bolts or the like (not shown). Accordingly, by arbitrarily changing the material, surface shape and / or surface structure of the surface layer material 4c2, approximate models of various club faces can be created and the contact force can be measured.

  The material of the main body 4c1 is not limited, but generally stainless steel (SUS-630) is used. The thickness of the main body 4c1 is usually 10 mm to 20 mm. Moreover, the planar shape of the main body 4c1 can be made substantially the same as the planar shape of the pressure sensor 4b, for example, a square having a side of 40 mm to 60 mm. The main bolt 4d is screwed into the main body 4c1. As a result, the pressure sensor 4b is sandwiched between the base plate 4a and the main body 4c1, and the position thereof is fixed.

  The surface layer material 4c2 forming the striking surface 3 of the collision plate 4 can employ various materials, surface shapes, and surface structures, but is formed of the same material as the face (not shown) of the golf club head set in advance as an analysis target. It is good. In the present invention, from the viewpoint of evaluating an approach shot model, the surface layer material 4c2 is made of, for example, SUS-431 stainless steel, which is the same material as the head material of CG-15 manufactured by Cleveland Golf. The thickness of the surface layer material 4c2 can be arbitrarily changed, and is, for example, 1.0 mm to 5.0 mm. The planar shape of the surface layer material 4c2 is substantially the same as the planar shape of the main body 4c1, and can be, for example, a square having a side of 40 mm to 60 mm.

  Further, the contact force tester 1 includes a strobe device 7 and a high-speed camera device 8 that can photograph the golf ball 2 that collides with the striking surface 3 and the golf ball 2 and bounces and bounces back. The strobe device 7 is connected to a strobe power supply 9. The camera device 8 is connected to a camera power supply 10 via a capacitor box. Then, the imaged data is stored in the computer device PC or the like. By including these devices, it is possible to measure a sliding speed, a contact area, a golf ball launch speed, a launch angle, a backspin amount, and the like at the time of collision between a golf ball 2 and a striking surface 3 described later.

  FIG. 4 shows a time history of the normal force Fn and the shear force Ft received by the striking surface 3 when the golf ball 2 and the striking surface 3 of one condition measured by the contact force tester 1 collide.

  FIG. 4 is a graph showing an example of Fn (t) and Ft (t) measured by the measuring apparatus of FIGS. 2 and 3. In FIG. 4, a point P <b> 0 is a point at which the pressure sensor 4 b starts to sense force, and substantially corresponds to the start of the collision between the striking surface 3 and the golf ball 2. The contact force Fn (t) in the vertical direction gradually increases from the point P0, reaches a maximum value at the point P4, decreases from here, and becomes zero at the point P3. This point P3 is a point at which the pressure sensor 4b no longer senses force, and substantially corresponds to the time when the golf ball 2 is separated from the striking surface 3.

  On the other hand, the value of Ft (t), which is the contact force in the direction parallel to the collision plate (that is, shear force), increases from point P0 with time, reaches the maximum value at point P1, then decreases to zero at point P2, After that, it becomes a negative value. Since the golf ball is separated from the pressure sensor 4b at the point P3, the curve of Ft (t) sensed by the pressure sensor 4b becomes zero at the point P3. Of the region surrounded by the curve of Ft (t) and the time axis, the area S1 of the region where Ft (t) takes a positive value represents an impulse with a positive shearing force. On the other hand, of the region surrounded by the curve of Ft (t) and the time axis, the area S2 of the region where Ft (t) takes a negative value represents an impulse with a negative shearing force. The impulse S1 acts in the direction of promoting backspin, and the impulse S2 acts in a direction of suppressing backspin. Here, the impulse S1 is larger than the impulse S2, and a value obtained by subtracting the impulse S2 from the impulse S1 contributes to the backspin of the golf ball.

  The friction coefficient can be obtained by calculating the maximum value of M (t) obtained by Ft (t) / Fn (t).

  In the present invention, the friction coefficient obtained as described above is preferably 0.35 or more, more preferably 0.37 or more, further preferably 0.39 or more, preferably 0.60 or less, and 0.56 or less. More preferred is 0.54 or less. If the friction coefficient is within the above range, the spin amount of the approach shot becomes good.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range.

[Evaluation method]
(1) Mechanical properties of the cover Using the cover composition, a sheet having a thickness of about 2 mm was produced by injection molding and stored at 23 ° C. for 2 weeks. In accordance with ISO 527-1, a dumbbell-shaped test piece (distance between marked lines: 73 mm, width of parallel part: 5.0 mm) is produced from this sheet, and a tensile test measuring device (tensile speed: 100 mm / min) manufactured by Shimadzu Corporation. , Measurement temperature: 23 ° C.), the physical properties of the cover were measured, and the modulus (tensile modulus) at 10% elongation was calculated.

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

(3) Mechanical properties of the coating film The coating material containing the main agent and the curing agent was dried and cured at 40 ° C. for 4 hours to prepare a coating film. According to JIS-K7161, this coating film was punched into a dumbbell shape (distance between marked lines: 20 mm, width of parallel part: 10 mm) to prepare a test piece, and the coating film was formed using a tensile test measuring device manufactured by Shimadzu Corporation. The physical properties were measured, and the modulus (tensile modulus) at 10% elongation was calculated.
Film thickness of test piece: 0.05mm
Tensile speed: 50 mm / min Measurement temperature: 23 ° C.

(4) Measurement of friction coefficient and spin amount Using a contact force tester shown in FIG. 2, the friction coefficient and spin amount of a golf ball were measured.
(4-1) Specifications of measuring device (A) Launcher: Air gun type (B) Colliding plate:
・ Base plate 4a
Steel thickness: 5.35mm
・ Surface plate 4c
Body 4c1
Size: 56mm x 56mm x 15mm
Stainless steel (SUS-630)
Surface material 4c2
Size: 56mm x 56mm x 2.5mm
Metal composition: SUS-431
Groove shape: See Fig. 5 ・ Inclination angle (α)
35 degrees (relative to golf ball flight direction)
(C) Pressure sensor 4b
Kistler's three-component force sensor (model 9067)
Charge amplifier Kistler Model 5011B
(D) Incorporation of contact force into PC A pulse counter board PCI-6101 (manufactured by Interface Co., Ltd.) was used. A PCI pulse counter board with 16 bits and 4 channels can be used for measurement in 4 different counter modes. The maximum input frequency is 1MHz.

As shown in FIG. 5, the groove structure of the sand wedge CG-15 manufactured by Cleveland is reproduced on the striking surface 3 of the collision plate 4. As shown in FIG. 5A, the striking surface 3 is provided with a plurality of small grooves on the surface between the large groove (zip groove) and the large groove (zip groove). FIG. 5B is an enlarged view of the cross-sectional structure of the zip groove. The dimensions of the zip groove are as follows.
Zip groove width W: 0.70mm
Zip groove (groove) depth h: 0.50 mm
Zip groove pitch: 3.56mm
Zip groove angle α: 10 °
Zip groove shoulder R: 0.25
The plurality of small grooves between the zip grooves are formed by laser milling so that the surface portion between the zip grooves has a surface roughness Ra = 2.40 ± 0.8 μm and Rmax = 14.0 ± 8 μm. . The surface roughness Ra and Rmax are measured using SJ-301 manufactured by Mitutoyo under measurement conditions of measurement length = 2.5 mm and cutoff value = 2.5 mm.

(4-2) Measurement procedure The coefficient of friction was measured by the following method. The measurement temperature was 23 ° C. and the initial ball speed was 9 m / s. The measurement was performed 12 times for each golf ball, and the average value was taken as the measured value of the golf ball.
(A) The angle (α) of the collision plate was set to 35 degrees with respect to the flight direction (vertical direction) of the golf ball.
(B) The air pressure of the launcher 5 is adjusted.
(C) A golf ball is launched from the launching device at a speed of 9 m / s.
(D) The initial velocity of the golf ball is measured from the preset distance between the sensors S1 and S2 and the golf ball shielding time difference between them.
(E) The contact force Fn (t) and the contact force Ft (t) are measured, and the maximum value of Ft (t) / Fn (t) is calculated.
(F) The spin amount of the golf ball is measured with a strobe device and a camera device.

(4-3) Measurement Results FIG. 6 shows an example of the results measured by the test apparatus and measurement procedure. From FIG. 6, the value of M (t) is calculated as Ft (t) / Fn (t), and its maximum value is 0.58. Since Ft and Fn are likely to generate noise at the initial stage and the final stage when the contact force rises, the maximum value of M (t) is calculated by trimming the initial stage and the final stage.

(5) Driver flight distance (m)
A swing head M / C manufactured by Golf Laboratories is attached with a W # 1 driver (manufactured by Dunlop Sports, XXIO S Loft 11 °) and a golf ball is hit at a head speed of 40 m / sec. The distance from the starting point to the stationary point) was measured. The measurement was performed 12 times for each golf ball, and the average value was taken as the measured value of the golf ball.

(6) Contamination Resistance A golf ball was taken out by immersing in iodine tincture water diluted 40 times with iodine tincture (ethanol solution containing 6% by mass of iodine and 4% by mass of potassium iodide) for 30 seconds. After wiping off excess iodine tincture water adhering to the surface of the golf ball, the color difference (L, a, b) of the golf ball before and after immersion was measured using a color difference meter (CM3500D manufactured by Konica Minolta). (ΔE) was calculated by the following equation. Note that the greater the color difference (ΔE) value, the greater the degree of discoloration.
ΔE = [(ΔL) ² + (Δa) ² + (Δb) ² ] ^1/2
Evaluation criteria A: ΔE is 15 or less ○: ΔE is more than 15 and less than 20 Δ: ΔE is more than 20 and less than 25 ×: ΔE is 25 or more

(7) Feeling of hitting An actual golf hit test using a sand wedge (CG15 forged wedge (52 °) manufactured by Cleveland Golf Co., Ltd.) was conducted by 10 amateur golfers (advanced players). Based on the number of people who answered that they had a good feeling (it feels like they are on the face, they can feel snags, they feel like they are spinning, they feel good) Evaluated.
◎: 8 or more ○: 4 to 7 △: 3 or less

[Three-Piece Golf Ball No. 1-No. 19]
1. Production of Center A rubber composition for a center having the composition shown in Table 1 was kneaded and heated and pressed in an upper and lower mold having hemispherical cavities at 170 ° C. for 20 minutes to obtain a spherical center having a diameter of 39.2 mm.

ポリブタジエンゴム：ＪＳＲ（株）製、「ＢＲ７３０（ハイシスポリブタジエン）」
アクリル酸亜鉛：日本蒸溜工業社製、「ＺＮ−ＤＡ９０Ｓ」
酸化亜鉛：東邦亜鉛社製、「銀嶺Ｒ」
硫酸バリウム：堺化学社製、「硫酸バリウムＢＤ」
ジフェニルジスルフィド：住友精化社製
ジクミルパーオキサイド：日油社製、「パークミル（登録商標）Ｄ」

Polybutadiene rubber: “BR730 (high cis polybutadiene)” manufactured by JSR Corporation
Zinc acrylate: Nippon Distillation Industrial Co., Ltd. “ZN-DA90S”
Zinc oxide: Toho Zinc Co., Ltd.
Barium sulfate: Sakai Chemical Co., Ltd. “Barium sulfate BD”
Diphenyl disulfide: Dicumyl peroxide manufactured by Sumitomo Seika Co., Ltd .: NOF Corporation, “Park Mill (registered trademark) D”

2. Preparation of Intermediate Layer Composition and Cover Composition The materials having the formulations shown in Tables 2 and 3 were mixed with a twin-screw kneading extruder to obtain pellet-like intermediate layer composition and cover composition. Prepared. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D = 35, and the blend was heated to 200-260 ° C. at the die position of the extruder.

サーリン８９４５：デュポン社製、ナトリウムイオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂
ハイミランＡＭ７３２９：三井・デュポン・ポリケミカル社製、亜鉛イオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂

Surlyn 8945: manufactured by DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himiran AM7329: manufactured by Mitsui DuPont Polychemical Co., Ltd., zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin

ハイミランＡＭ７３２７：三井・デュポン・ポリケミカル社製、亜鉛イオン中和エチレン−メタクリル酸−アクリル酸ブチル三元共重合体系アイオノマー樹脂
ＨＰＦ１０００：デュポン社製、マグネシウムイオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂
ハイミラン１６０５：三井・デュポン・ポリケミカル社製、ナトリウムイオン中和エチレン−メタクリル酸共重合体系アイオノマー樹脂
ハイミランＡＭ７３２９：三井・デュポン・ポリケミカル社製、亜鉛イオン中和エチレン−メタクリル酸共重合体系アイオノマー樹脂
ラバロンＴ３２２１Ｃ：三菱化学社製、熱可塑性ポリスチレンエラストマー
サーリン８１５０：デュポン社製、ナトリウムイオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂
サーリン９１５０：デュポン社製、亜鉛イオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂
サーリン８９４５：デュポン社製、ナトリウムイオン中和エチレン−メタクリル酸共重合体アイオノマー樹脂
ノバミッドＳＴ１２０：ＤＳＭジャパンエンジニアリングプラスチックス社製、ポリアミド樹脂組成物

High Milan AM7327: Mitsui DuPont Polychemical Co., Ltd., zinc ion neutralized ethylene-methacrylic acid-butyl acrylate terpolymer ionomer resin HPF1000: DuPont, magnesium ion neutralized ethylene-methacrylic acid copolymer ionomer resin High Milan 1605: Made by Mitsui-DuPont Polychemical, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Lavalon T3221C: manufactured by Mitsubishi Chemical Corporation, thermoplastic polystyrene elastomer Surlyn 8150: manufactured by DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Surlyn 9150: Zupon, zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin Surlyn 8945: DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Novamid ST120: DSM Japan Engineering Plastics, polyamide resin Composition

3. Production of Spherical Core The intermediate layer composition obtained above is directly injection-molded on the center obtained as described above to form an intermediate layer (thickness: 1.0 mm) covering the center. Thus, a spherical core was produced. The upper and lower molds for molding have a hemispherical cavity and a hold pin that can move forward and backward to support the spherical core. At the time of forming the intermediate layer, the hold pin is protruded, the center is inserted and held, and the intermediate layer composition heated to 260 ° C. is injected into the mold clamped at a pressure of 80 tons in 0.3 seconds, and 30 seconds. After cooling, the mold was opened and the spherical core was taken out.

4). Molding of half shell In compression molding of half shell, the obtained pellet-shaped cover composition was put in one for each concave portion of the lower mold of the mold for molding half shell, and pressed to mold the half shell. The compression molding was performed under the conditions of a molding temperature of 170 ° C., a molding time of 5 minutes, and a molding pressure of 2.94 MPa.

5. Formation of Cover The spherical core obtained above was concentrically covered with two half shells, and a cover (thickness: 0.8 mm) was formed by compression molding. The compression molding was performed under the conditions of a molding temperature of 145 ° C., a molding time of 2 minutes, and a molding pressure of 9.8 MPa.

6). Preparation of paint Preparation of main agent Polytetramethylene ether glycol (PTMG) and trimethylolpropane (TMP) were dissolved in a solvent (toluene, methyl ethyl ketone) as a polyol component. Dibutyltin laurate was added here as a catalyst so that it might become 0.1 mass% with respect to the whole main ingredient. While maintaining this polyol solution at 80 ° C., isophorone diisocyanate (IPDI) as a polyisocyanate component was mixed dropwise. After dropping, stirring was continued until the isocyanate disappeared, and then cooled at room temperature to prepare urethane polyol (solid content: 30% by mass). Table 4 shows the composition and the like of each urethane polyol.

Preparation of Curing Agent Isocyanurate-modified product of hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals, Duranate (registered trademark) TKA-100 (NCO content: 21.7% by mass)), burette-modified product of hexamethylene diisocyanate ( Asahi Kasei Chemicals, Duranate 21S-75E (NCO content: 15.5% by mass), 30 parts by mass, isophorone diisocyanate (BAYER, Desmodur (registered trademark) Z 4470 (NCO content: 11.9% by mass) )) 40 parts by mass were mixed. Here, a mixed solvent of methyl ethyl ketone, n-butyl acetate and toluene was added as a solvent, and the concentration of the polyisocyanate component was adjusted to 60% by mass.

Preparation of paint A paint was prepared by blending a curing agent with the main agent prepared above so that the NCO / OH ratios shown in Tables 5 and 6 were obtained.

7). Formation of Coating Film After the surface of the golf ball body obtained above is sandblasted and marked, the paint is applied with a spray gun, and the paint is dried in an oven at 40 ° C. for 24 hours. A golf ball was obtained. The thickness of the coating film was 20 μm. The coating is performed by placing the golf ball body 20 on the rotating body 30 having the three prongs 30a to 30c shown in FIG. 7, rotating the rotating body at 300 rpm, and spraying an air gun 31 from the golf ball body (7 cm). ) Separated and moved up and down. The interval of each overcoating was 1.0 second. Air gun spraying conditions are: overcoat; twice, spray air pressure; 0.15 MPa, pressure tank air pressure; 0.10 MPa, one application time; 1 second, ambient temperature; 20 ° C. to 27 ° C., ambient humidity; The coating was performed under a condition of 65% or less. Tables 5 and 6 also show the evaluation results of the obtained golf balls.

Golf ball no. 2-5, 7-10, 12-14, 17-19, the polyol composition which comprises a coating film contains the urethane polyol which contains polyether diol whose number average molecular weight is 800-3000 as a structural component, The 10% modulus of the coating film is 100 kgf / cm ² or less, and the 10% modulus (kgf / cm ² ) of the coating film and the molar ratio (NCO / OH) satisfy the relationship of formula (1), The 10% modulus of the cover is 120 kgf / cm ² or more. These golf balls have a great flight distance on driver shots and are excellent in contamination resistance and feel at impact.

  The present invention can be suitably applied to a painted golf ball.

1: contact force tester, 2: golf ball, 3: striking surface, 4: collision plate, 5: launching device, 6: controller, 7: strobe device, 8: high-speed camera device, 9: strobe power supply, 10 : Camera power supply, Fn: Normal force in a direction perpendicular to the striking surface, Ft: Shear force in a direction parallel to the striking surface, 20: Golf ball, 21: Spherical core, 22: Cover, 23: Coating film, 24: Dimple 25: Land, 30: Rotating body, 30a-30c: Prong, 31: Air gun

Claims (11)

A golf ball having a core and a cover that covers the core, and a coating film provided on the surface of the golf ball body,
The base resin constituting the coating film is a polyurethane obtained by reacting a polyol composition and a polyisocyanate composition,
The polyol composition contains a urethane polyol containing a polyether diol having a number average molecular weight of 800 to 3000 as a constituent component,
10% modulus of the coating film is 100 kgf / cm ² or less,
The 10% modulus (kgf / cm ² ) of the coating film, and the molar ratio (NCO / OH) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition are as follows: Satisfying the relationship of formula (1),
A golf ball characterized in that a 10% modulus of the cover is 120 kgf / cm ² or more.
Y ≦ 200 × X−75 (1)
[Wherein Y is the 10% modulus (kgf / cm ² ) of the coating film, and X is the molar ratio (NCO group) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition. / OH). ]   The molar ratio (NCO / OH) of the hydroxyl group (OH group) of the polyol composition to the isocyanate group (NCO group) of the polyisocyanate composition is more than 0.5 and 1.2 or less. The golf ball described.   The golf ball according to claim 1, wherein the urethane polyol has a hydroxyl value of 10 mgKOH / g to 200 mgKOH / g.   The golf ball according to claim 1, wherein the urethane polyol contains a triol component as a constituent component.   The golf ball according to claim 4, wherein the polyol component constituting the urethane polyol has a mass ratio of a mixing ratio of the triol component and the diol component (triol component / diol component) of 0.2 to 6.0.   The golf ball according to claim 1, wherein the polyisocyanate composition contains a triisocyanate compound.   The golf ball according to claim 6, wherein the content of the triisocyanate compound in the polyisocyanate compound contained in the polyisocyanate composition is 50% by mass or more.   The golf ball according to claim 1, wherein a friction coefficient calculated using a contact force tester is 0.35 or more and 0.60 or less.   The golf ball according to claim 1, wherein the coating film has a thickness of 5 μm or more and 50 μm or less. The golf ball according to claim 1, wherein the cover has a 10% modulus of 280 kgf / cm ² or less.   The golf ball according to any one of claims 1 to 10, wherein the slab hardness of the cover is Shore D hardness and is more than 60.

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