JP6385105B2 - Golf ball - Google Patents

Description

  The present invention relates to a golf ball, and more particularly, to a golf ball having both a flight distance on a driver shot and a spin amount on an approach shot, and excellent in stain resistance and feel at impact.

  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.

For example, 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. A golf ball having a Martens 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 addition, a golf ball has been proposed in which the spin amount and flight distance are improved by adjusting the hardness distribution of the components of the golf ball. For example, Patent Document 3 discloses a golf ball including a central portion, at least two intermediate layers that sequentially enclose the central portion, and an outer layer that encloses the intermediate layer, and the outer layer includes: The first intermediate layer that has a Shore D hardness of 40 to 50 and is located immediately below the outer layer among the intermediate layers has a Shore D hardness of 50 to 65 and is located directly below the first intermediate layer. Each of the intermediate layers has a Shore D hardness of 30 to 70, a Shore D hardness of the central portion of 30 to 70, and a golf ball having a moment of inertia value of 83 g · cm ² or less. ing.

JP 2011-67595 A JP 2011-217820 A JP 2011-255172 A

  In the prior art, the spin performance is enhanced 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. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a golf ball having both a flight distance on a driver shot and a spin amount on an approach shot, and having excellent anti-contamination and feel at impact. And

The golf ball of the present invention comprises a golf ball body having a spherical core, an intermediate layer covering the spherical core, and a cover covering the intermediate layer, 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, and the polyol composition contains a polyether diol having a number average molecular weight of 800 to 3000. A urethane polyol contained as a constituent component, 10% modulus Mp (kgf / cm ² ) of the coating film, 10% modulus Mm (kgf / cm ² ) of the intermediate layer, and 10% modulus Mc (kgf of the cover) / ^cm 2), thickness Tp of the coating film (mm), the thickness Tm of the intermediate layer (mm), the thickness Tc of the cover (mm), and Molar ratio (NCO / OH) X of serial polyol hydroxyl composition having (OH groups) and isocyanate groups polyisocyanate composition has (NCO groups) is characterized by satisfying the following requirements.
Mp ≦ 200 × X-75
Mp ≦ 100
Mm-Mc> 100
Tm>Tc> Tp
(Tm × Mm) / (Tc × Mc)> 7.5
(Tc × Mc) / (Tp × Mp)> 2.4

The absolute value (| Mp−Mc |) of the difference between the 10% modulus Mp (kgf / cm ² ) of the coating film and the 10% modulus Mc (kgf / cm ² ) of the cover is preferably 65 or less. The proportion of the volume Vc of the cover in the golf ball body is preferably less than 10% by volume. The 10% modulus Mc (kgf / cm ² ) of the cover is preferably 20 or less. The intermediate layer preferably has a 10% modulus Mm (kgf / cm ² ) of 120 or more. The difference (Hs−Ho) between the surface hardness Hs and the center hardness Ho of the spherical core is JIS-C hardness, preferably 20 or more. The spherical core preferably has at least one layer formed of a rubber composition containing a fatty acid and / or a metal salt thereof.

  According to the present invention, it is possible to obtain a golf ball that achieves both a flight distance on a driver shot and a spin amount on an approach shot, 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.

The golf ball of the present invention includes a golf ball body having a spherical core, an intermediate layer covering the spherical core, and a cover covering the intermediate layer, and a coating film provided on the surface of the golf ball body. And 10% modulus Mp (kgf / cm ² ) of the coating film, 10% modulus Mm (kgf / cm ² ) of the intermediate layer, 10% modulus Mc (kgf / cm ² ) of the cover, The thickness Tp (mm), the thickness Tm (mm) of the intermediate layer, the thickness Tc (mm) of the cover, and the hydroxyl group (OH group) of the polyol composition and the isocyanate group of the polyisocyanate composition ( NCO group) molar ratio (NCO / OH) X satisfies the following requirements.
Mp ≦ 200 × X-75
Mp ≦ 100
Mm-Mc> 100
Tm>Tc> Tp
(Tm × Mm) / (Tc × Mc)> 7.5
(Tc × Mc) / (Tp × Mp)> 2.4

In the golf ball of the present invention, the intermediate layer, the cover, and the coating film are designed to be softer and thinner at the portion closer to the ball surface. With such a configuration, it is possible to obtain a golf ball having a large spin amount on approach shots and a small spin amount on driver shots. The coating film has an Mp of 100 kgf / cm ² or less, and the Mp and the X satisfy the above relationship. That is, even if the molar ratio (NCO / OH) is increased, the coating film has high flexibility, so that the spin rate at the approach shot is high and the stain resistance is excellent.

(Mp ≦ 200 × X-75)
The coating film has a 10% modulus Mp (kgf / cm ² ), and a molar ratio (NCO / OH) X of the hydroxyl group (OH group) of the polyol composition and the isocyanate group (NCO group) of the polyisocyanate composition. Satisfies the relationship of the following formula. Those satisfying the following formula can maintain the flexibility of the coating film even when the molar ratio (NCO / OH) is increased, so that the amount of spin on approach shot is high and the stain resistance is excellent.
Mp ≦ 200 × X-75

(Mp)
The 10% modulus Mp 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. When the 10% modulus of the coating film exceeds 100 kgf / cm ² , the shot feeling is lowered and the spin rate of the approach shot is lowered. 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). If the 10% modulus of the coating film is too small, the film becomes too soft, and a tacky feeling remains, resulting in poor feeling.

(Mm-Mc)
The difference (Mm−Mc) between 10% modulus Mm (kgf / cm ² ) of the intermediate layer and 10% modulus Mc (kgf / cm ² ) of the cover is more than 100 kgf / cm ² (9.8 MPa). It is preferably more than 150 kgf / cm ² (14.7 MPa), more preferably more than 180 kgf / cm ² (17.7 MPa). When the difference (Mm−Mc) is 100 kgf / cm ² or less, the spin rate on the driver shot increases and the flight distance decreases, or the spin rate on the approach shot decreases. The upper limit is not particularly limited in the difference (Mm-Mc), usually 350kgf ^/ cm 2 (34.3MPa), preferably 320kgf ^/ cm 2 (31.4MPa), and more preferably 300kgf ^/ cm 2 (29.4MPa) It is.

(│Mp-Mc│)
The absolute value (| Mp−Mc |) of the difference between the 10% modulus Mp (kgf / cm ² ) of the coating film and the 10% modulus Mc (kgf / cm ² ) of the cover is 65 kgf / cm ² (6. 4 MPa) or less, and more preferably 60kgf ^/ cm 2 (5.9MPa), and more preferably not more than 55kgf ^/ cm 2 (5.4MPa). When the absolute value (| Mp−Mc |) is 65 kgf / cm ² or less, the shot feeling is improved and the spin rate at the approach shot is improved. The lower limit of the absolute value (| Mp−Mc |) of the difference is zero.

(Tm>Tc> Tp)
The thickness Tm of the intermediate layer is larger than the thickness Tc of the cover (Tm> Tc), and the thickness Tc of the cover is larger than the thickness Tp of the coating film (Tc> Tp). When the thickness Tm of the intermediate layer is smaller than or equal to the thickness Tc of the cover, or when the thickness Tc of the cover is smaller than or equal to the thickness Tp of the coating film, driver shot The spin amount at the time increases, and the flight distance decreases, or the spin amount at the approach shot decreases.

((Tm × Mm) / (Tc × Mc))
The product (Tm × Mm) of the thickness Tm (mm) of the intermediate layer and 10% modulus Mm (kgf / cm ² ), the thickness Tc (mm) of the cover, and 10% modulus Mc (kgf / cm ^2). ) And the product (Tc × Mc) ((Tm × Mm) / (Tc × Mc)) is more than 7.5, preferably more than 9.0, more preferably more than 10.0 . When the ratio ((Tm × Mm) / (Tc × Mc)) is 7.5 or less, the spin amount on the driver shot increases and the flight distance decreases, or the spin amount on the approach shot decreases. . The upper limit of the ratio ((Tm × Mm) / (Tc × Mc)) is not particularly limited, but is preferably 100 or less, more preferably 75 or less, and even more preferably 60 or less.

((Tc × Mc) / (Tp × Mp))
The product (Tc × Mc) of the cover thickness Tc (mm) and 10% modulus Mc (kgf / cm ² ), the coating thickness Tp (mm) and 10% modulus Mp (kgf / cm ²⁾ ) And the product (Tp × Mp) ((Tc × Mc) / (Tp × Mp)) is greater than 2.4, preferably greater than 2.7, more preferably greater than 3.0. . When the ratio ((Tc × Mc) / (Tp × Mp)) is 2.4 or less, the spin amount on the driver shot increases and the flight distance decreases, or the spin amount on the approach shot decreases. . The upper limit of the ratio ((Tc × Mc) / (Tp × Mp)) is not particularly limited, but is preferably 26 or less, more preferably 23 or less, and still more preferably 20 or less.

(Tp x Mp)
The product (Tp × Mp) of the thickness Tp (mm) of the coating film and 10% modulus Mp (kgf / cm ² ) is preferably 0.2 or more, more preferably 0.4 or more, and still more preferably 0. It is 0.5 or more, 4.0 or less is preferable, More preferably, it is 3.0 or less, More preferably, it is 2.5 or less. If the product (Tp × Mp) is 0.2 or more, the contamination resistance is further improved, and if it is 4.0 or less, the spin performance on the approach shot is further improved.

(Tm x Mm)
The product (Tm × Mm) of the thickness Tm (mm) of the intermediate layer and 10% modulus Mm (kgf / cm ² ) is preferably 120 or more, more preferably 140 or more, still more preferably 160 or more, 400 or less is preferable, More preferably, it is 370 or less, More preferably, it is 340 or less. If the product (Tm × Mm) is 120 or more, the spin rate on driver shots is reduced and the flight distance is further improved. If it is 400 or less, the spin performance in the approach shot is further improved.

(Tc x Mc)
The product (Tc × Mc) of the cover thickness Tc (mm) and 10% modulus Mc (kgf / cm ² ) is preferably 2.0 or more, more preferably 3.0 or more, and still more preferably 4. It is 0 or more, 26.0 or less are preferable, More preferably, it is 24.0 or less, More preferably, it is 22.0 or less. If the product (Tc × Mc) is 2.0 or more, the spin performance on the approach shot is further improved. On the other hand, if it is 26.0 or less, the spin amount on the driver shot is reduced, and the flight distance is further improved.

[Coating]
Hereinafter, each component of the golf ball of the present invention will be described. 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.

  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, and the spin performance on approach shots is improved. 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 cross-linking points in the coating film becomes long and the coating film becomes soft, so that the spin performance is improved. 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 ratio of the polyether diol is 70% by mass or more, the spin performance 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 cross-linking points in the coating film becomes long and the coating film becomes soft, so that the spin performance is 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. can be mentioned.

  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 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.

(Tp)
The thickness Tp of the coating film after drying is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. When the film thickness is less than 5 μm, the coating tends to be worn away by continuous use. In addition, the spin amount of the approach shot increases 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.

[Golf ball body]
The golf ball body includes a spherical core, an intermediate layer that covers the spherical core, and a cover that covers the intermediate layer.

[Spherical core]
The structure of the spherical core is not particularly limited, and may be a single layer structure or a multilayer structure of two or more layers. Since the hardness design is easy, a two-layer core composed of a spherical inner layer core and an outer layer core covering the inner layer core is preferable.

  The hardness difference (Hs-Ho) between the surface hardness Hs and the center hardness Ho of the spherical core is preferably JIS-C hardness of 20 or more, more preferably 24 or more, and further preferably 28 or more. If the hardness difference (Hs−Ho) is 20 or more, the spin rate on driver shots decreases and the flight distance improves. The upper limit of the hardness difference (Hs-Ho) is not particularly limited, but is preferably 50 or less, more preferably 45 or less, and still more preferably 40 or less.

  The center hardness Ho of the spherical core is JIS-C hardness, preferably 40 or more, more preferably 50 or more, and still more preferably 55 or more. When the center hardness Ho of the spherical core is 40 or more in terms of JIS-C hardness, the resilience is good. Further, the central hardness Ho of the spherical core is preferably 80 or less in JIS-C hardness, more preferably 76 or less, and further preferably 72 or less. If the center hardness Ho is 80 or less in terms of JIS-C hardness, the spin rate on driver shots decreases.

  The surface hardness Hs of the spherical core is JIS-C hardness, preferably 80 or more, more preferably 82 or more, still more preferably 84 or more, preferably 96 or less, more preferably 94 or less, still more preferably 92 or less. is there. If the surface hardness of the spherical core is 80 or more in terms of JIS-C hardness, the spin rate on driver shots decreases. If the surface hardness of the spherical core is 96 or less in JIS-C hardness, the spherical core will not be too hard and the durability will be good.

  The diameter of the spherical core is preferably 38.0 mm or more, more preferably 38.5 mm or more, and further preferably 39.5 mm or more. If the diameter of the spherical core is 38.0 mm or more, the resilience is better. The upper limit of the diameter of the spherical core is not particularly limited, but is preferably 41.5 mm or less, more preferably 41.0 mm or less, and further preferably 40.5 mm or less.

  When the spherical core has a diameter of 38.0 mm to 41.5 mm, the amount of compressive deformation (the amount by which the core contracts in the compression direction) from when the initial load is 98 N to when the final load is 1275 N is 2.3 mm. The above is preferable, More preferably, it is 2.5 mm or more, 4.5 mm or less is preferable, More preferably, it is 4.2 mm or less. If the amount of compressive deformation is 2.3 mm or more, the feel at impact is better, and if it is 4.5 mm or less, the resilience is better.

  For the spherical core, a known rubber composition (hereinafter sometimes simply referred to as “core rubber composition”) can be used. For example, a rubber composition containing a base rubber, a co-crosslinking agent, and a crosslinking initiator. The product 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 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 fatty acid and / or a metal salt thereof. As the fatty acid, either a saturated fatty acid or an unsaturated fatty acid can be used, but a saturated fatty acid is preferred. Examples of saturated fatty acids include caprylic acid (octanoic acid), pelargonic acid (nonanoic acid), capric acid (decanoic acid), lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. As the metal of the metal salt, zinc, magnesium, calcium, aluminum, and sodium are preferable, and zinc is more preferable. The fatty acid and / or metal salt thereof does not include the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof used as the co-crosslinking agent.

  The compounding quantity of the said fatty acid and / or its metal salt is 1 to 40 mass parts with respect to 100 mass parts of base rubber. Note that the surface of zinc acrylate used as a co-crosslinking agent may be treated with zinc stearate in order to improve dispersibility in rubber. In the case of using zinc acrylate surface-treated with such zinc stearate, the amount of zinc stearate as a surface treatment agent is included in the content of fatty acid and / or metal salt thereof.

  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.

[Middle layer]
The golf ball body has an intermediate layer disposed outside the spherical core. The intermediate layer has a relatively large 10% modulus value. By providing such an intermediate layer, it is possible to reduce the spin rate on a golf ball driver shot.

(Tm)
The thickness Tm of the intermediate layer is preferably 0.7 mm or more, more preferably 0.8 mm or more, further preferably 0.9 mm or more, preferably 1.6 mm or less, more preferably 1.4 mm or less, and further preferably. Is 1.2 mm or less. If the thickness of the intermediate layer is 0.7 mm or more, the durability of the golf ball is improved. If the thickness is 1.6 mm or less, the core diameter is relatively increased, and the resilience performance is improved.

(Mm)
10% modulus Mm of the middle layer is ^preferably at least 120kgf / cm 2 (11.8MPa), and more preferably 140kgf ^/ cm 2 (13.7MPa) or more, more preferably 160kgf ^/ cm 2 (15.7MPa) or It is. If the 10% modulus of the intermediate layer is 120 kgf / cm ² or more, the spin rate on driver shots decreases and the flight distance improves. The upper limit of the 10% modulus of the intermediate layer is not particularly ^limited, but is preferably ^{400kgf / cm 2 (39.2MPa),} 370kgf / cm 2 (36.3MPa) is more preferable.

(Hm)
The intermediate layer has a Shore D hardness of preferably 62 or more, more preferably 65 or more, still more preferably 68 or more, and is preferably 75 or less, more preferably 74 or less, and even more preferably 73 or less. If the hardness is 62 or more in Shore D hardness, the spin rate on the driver shot is reduced and the flight distance is further improved. Moreover, if it is 75 or less, a shot feeling will become more favorable. The hardness of the intermediate layer is a slab hardness measured by molding the intermediate layer composition forming the intermediate layer into a sheet shape.

(Vm)
The ratio of the volume Vm of the intermediate layer in the golf ball body is preferably 8% by volume or more, more preferably 10% by volume or more, still more preferably 11% by volume or more, and preferably 20% by volume or less. Preferably it is 18 volume% or less, More preferably, it is 16 volume% or less. If the ratio is 8% by volume or more, the spin rate on driver shots is reduced and the flight distance is further improved, and if it is 20% by volume or less, the feel at impact is improved. The volume of the golf ball body is a volume when it is assumed that no dimples are formed.

  Examples of the material for the intermediate layer include thermoplastic resins such as polyurethane resins, ionomer resins, polyamide resins, and polyethylene; thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyurethane elastomers, and polyester elastomers; cured products of rubber compositions; Is mentioned. 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.

  A specific example of the material of the intermediate layer is exemplified by a trade name. An ionomer resin commercially available from Mitsui DuPont Polychemical Co., Ltd. under the trade name “Himilan (registered trademark)” or a trade name “Nucler (registered)” (Trademark) ", an ethylene-methacrylic acid copolymer, commercially available from BASF Japan Ltd. under the trade name" Elastollan (registered trademark) ", and a polyurethane polyurethane elastomer commercially available from Arkema Co., Ltd. under the trade name" Thermoplastic polyamide elastomer marketed under the name “Pebax®”, thermoplastic polyester elastomer marketed under the trade name “Hytrel®” from Toray DuPont Co., Ltd., trade name from Mitsubishi Chemical Corporation Thermoplastic styrene elastomers or products marketed under "Lavalon (registered trademark)" , And the like thermoplastic polyester elastomer commercially available under the "Primalloy (registered trademark)". The material for the intermediate layer may be used alone or in admixture of two or more.

  The intermediate layer can be formed by directly injection-molding the intermediate layer composition onto the spherical core.

〔cover〕
The golf ball main body has a cover disposed outside the intermediate layer. The cover has a relatively small 10% modulus value. By providing such a cover, the spin performance on the approach shot is improved.

(Tc)
The thickness Tc of the cover is preferably 0.3 mm or more, more preferably 0.4 mm or more, further preferably 0.5 mm or more, preferably 0.8 mm or less, more preferably 0.7 mm or less, still more preferably. 0.5 mm or less. If the cover thickness is 0.3 mm or more, the spin performance on the approach shot is better, and if it is 0.8 mm or less, the spin amount on the driver shot is reduced and the flight distance is further improved.

(Mc)
The 10% modulus Mc of the cover is preferably 20 kgf / cm ² (2.0 MPa) or less, more preferably 18 kgf / cm ² (1.8 MPa) or less, and even more preferably 15 kgf / cm ² (1.5 MPa) or less. is there. If the 10% modulus of the cover is 20 kgf / cm ² or less, the feel at impact is improved and the spin rate of the approach shot is also increased. The lower limit of the 10% modulus of the cover is not particularly limited, but is preferably 3 kgf / cm ² (0.3 MPa), more preferably 6 kgf / cm ² (0.6 MPa).

(Hc)
The cover has a Shore D hardness of preferably 20 or more, more preferably 23 or more, still more preferably 25 or more, preferably 38 or less, more preferably 36 or less, and still more preferably 34 or less. If the cover has a Shore D hardness of 20 or more, the spin rate on the driver shot is reduced and the flight distance is improved, and if it is 38 or less, the spin performance on the approach shot is good. The cover hardness is a slab hardness measured by molding a cover composition for forming a cover into a sheet shape.

(Vc)
The ratio of the volume Vc of the cover in the golf ball body is preferably 3% by volume or more, more preferably 4% by volume or more, still more preferably 5% by volume or more, and preferably less than 10% by volume. Is 9% by volume or less, more preferably 8% by volume or less. If the ratio is 3% by volume or more, the spin performance on the approach shot is good, and if it is less than 10% by volume, the spin amount on the driver shot is reduced and the flight distance is improved. In addition, the volume of the golf ball main body and the volume of the cover are volumes when it is assumed that no dimples are formed.

  The cover material constituting the cover is not particularly limited, and examples thereof include ionomer resin, polyurethane, polyamide, polyester, polystyrene, and the like, and polyurethane and ionomer resin are preferable. In particular, polyurethane is preferable from the viewpoint of spin performance and scuff resistance in approach shots.

  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. An ionomer resin commercially available from Mitsui DuPont Polychemical Co., Ltd. under the trade name “Himilan (registered trademark)”, a trade name from BASF Japan Ltd. Thermoplastic polyurethane elastomer marketed by "Elastolan (registered trademark)", thermoplastic polyamide elastomer marketed by Arkema Co., Ltd. under the trade name "Pebax (registered trademark)", product from Toray DuPont Co., Ltd. The thermoplastic polyester elastomer marketed under the name “Hytrel” (registered trademark), the thermoplastic styrene elastomer marketed by Mitsubishi Chemical Co., Ltd. under the brand name “Lavalon®”, or the product name “Primalloy (registered trademark)” ) ”Is a commercially available thermoplastic polyester elastomer. Rukoto can. 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 (for example, a hindered amine light stabilizer), a fluorescent material, or a fluorescent brightening agent may be contained within a range not impairing the performance of the cover.

  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)

(Reinforcement layer)
The golf ball body may include a reinforcing layer between the intermediate layer and the cover. The reinforcing layer firmly adheres to the intermediate layer and also firmly adheres to the cover. The reinforcing layer suppresses peeling of the cover from the intermediate layer. In particular, when a golf ball having a thin cover is hit with the edge of a club face, wrinkles are likely to occur. Wrinkles are suppressed by the reinforcing layer.

  The reinforcing layer is formed from a reinforcing layer composition containing a resin component. As the resin component, a two-component curable thermosetting resin is preferably used. Specific examples of the two-component curable thermosetting resin include an epoxy resin, a urethane resin, an acrylic resin, a polyester resin, and a cellulose resin. From the viewpoint of the strength and durability of the reinforcing layer, a two-component curable epoxy resin and a two-component curable urethane resin are preferable.

  The composition for a reinforcing layer may contain additives such as a coloring material (for example, titanium dioxide), a phosphoric acid stabilizer, an antioxidant, a light stabilizer, a fluorescent brightener, an ultraviolet absorber, and an antiblocking agent. . The additive may be added to the main component of the two-component curable thermosetting resin, or may be added to the curing agent.

  The golf ball body preferably has a diameter of 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 large inertia, the mass is preferably 44 g or more, and more preferably 45 g or more. From the viewpoint that the USGA standard is satisfied, the mass is preferably equal to or less than 45.93 g.

  When the golf ball of the present invention has a diameter of 40 mm to 45 mm, the amount of compressive deformation (the amount of contraction in the compression direction) when the final load 1275N is applied from the state where the initial load 98N is applied may be 2.0 mm or more. More preferably, it is 2.2 mm or more, More preferably, it is 2.3 mm or more, Most preferably, it is 2.4 mm or more, It is preferable that it is 4.0 mm or less, More preferably, it is 3.7 mm or less is there. A golf ball having a compression deformation amount of 2.0 mm or more does not become too hard and has a good shot feeling. On the other hand, when the amount of compressive deformation is 4.0 mm or less, the resilience increases.

  The golf ball body has a three-layer golf ball having a single-layer core, an intermediate layer covering the single-layer core, and a cover covering the intermediate layer; a two-layer core and the two-layer core For example, a four-piece golf ball having an intermediate layer and a cover covering the intermediate layer.

  FIG. 1 is a partially cutaway sectional view showing a golf ball 1 according to an embodiment of the present invention. The golf ball 1 includes a spherical core 2 composed of a spherical inner layer core 21 and an outer layer core 22 disposed outside the inner layer core 21, and an intermediate layer 3 disposed outside the spherical core 2. The reinforcing layer 4 disposed outside the intermediate layer, the cover 5 disposed outside the reinforcing layer 4, and the coating film 6 disposed on the surface of the cover 5. A large number of dimples 51 are formed on the surface of the cover 5. Of the surface of the cover 5, a portion other than the dimples 51 is a land 52.

  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) 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.

(2) Core hardness (JIS-C hardness)
The JIS-C hardness measured on the surface of the core was used as the core surface hardness using an automatic rubber hardness meter P1 type manufactured by Kobunshi Keiki Co., Ltd. equipped with a spring type hardness meter JIS-C type. Further, the core was cut into a hemisphere, and the JIS-C hardness measured at the center of the cut surface was defined as the core center hardness.

(3) Compression deformation (mm)
The amount of deformation in the compression direction (the amount by which the golf ball shrinks in the compression direction) from when the initial load 98N was applied to the golf ball to when the final load 1275N was applied was measured.

(4) Mechanical properties of cover and intermediate layer Using the cover composition or the intermediate layer composition, a sheet having a thickness of about 2 mm was prepared 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 were measured, and the modulus (tensile modulus) at 10% elongation was calculated.

(5) Mechanical properties of the coating film A coating film 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.

(6) Restitution coefficient Each golf ball was impacted with 198.4 g of a metal cylinder at a speed of 45 m / sec, and the speed of the cylinder and the golf ball before and after the collision was measured. The coefficient of restitution of the ball was calculated. The measurement was performed 12 pieces for each golf ball, and the average value was used as the coefficient of restitution of the golf ball. The coefficient of restitution is the golf ball no. The coefficient of restitution of 1 is assumed to be 100, and is shown as an indexed value.

(7) Driver shot flight distance (m) and spin rate (rpm)
A driver equipped with a titanium head (Dunlop Sports, XXIO S Loft 10.0 °) is attached to a swing machine manufactured by True Temper, and a golf ball is hit at a head speed of 45 m / sec. Spin speed and flight distance (distance from launch point to rest point) were measured. The measurement was performed 10 times for each golf ball, and the average value was taken as the measured value of the golf ball. In addition, the spin speed of the golf ball immediately after hitting was measured by taking continuous photographs of the hit golf ball.

(8) Spin amount of approach shot A golf ball hit by hitting a golf ball at a head speed of 10 m / second by attaching a sand wedge (CG15 forged wedge (58 °)) manufactured by Cleveland Golf Co. to a swing machine manufactured by Trutemper. The spin rate (rpm) was measured by taking continuous pictures of the balls. The measurement was performed 10 times for each golf ball, and the average value was defined as the spin amount.

(9) Hit feeling A real hit test using a sand wedge (CG15 forged wedge (58 °) manufactured by Cleveland Golf Co., Ltd.) was performed 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

(10) 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

[Production of golf balls]
1. Production of Core An inner layer core was produced by kneading a rubber composition having the composition shown in Table 1 and thermoforming it in the upper and lower molds having hemispherical cavities under the conditions shown in Table 2. Next, a rubber composition having the composition shown in Table 1 was kneaded, and a half shell was molded using a half shell molding die. The inner layer core obtained above was concentrically covered with two half shells. These inner layer cores and the two half shells were heated and pressed under the conditions shown in Table 2 in upper and lower molds having hemispherical cavities to obtain spherical cores. The blending amount of barium sulfate was adjusted so that the finally obtained golf ball had a mass of 45.6 g.

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：三新化学社製、「サンセラー（登録商標） ＳＲ」（１０質量％ステアリン酸コーティング品）
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」
２−チオナフトール：東京化成工業社製
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」
オクタン酸亜鉛：三津和化学薬品社製

Polybutadiene rubber: “BR730 (high cis polybutadiene)” manufactured by JSR Corporation
Zinc acrylate: Sanshin Chemical Co., Ltd., “Sunseller (registered trademark) SR” (10% by mass stearic acid coating product)
Zinc oxide: Toho Zinc Co., Ltd.
Barium sulfate: Sakai Chemical Co., Ltd. “Barium sulfate BD”
2-thionaphthol: Dicumyl peroxide manufactured by Tokyo Chemical Industry Co., Ltd .: NOF Corporation, “Park Mill (registered trademark) D”
Zinc octoate: manufactured by Mitsuwa Chemicals

2. Preparation of Intermediate Layer Composition and Cover Composition The materials having the formulations shown in Tables 3 and 4 were mixed by 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 160-230 ° C. at the die position of the extruder.

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
ポリアミド６：東レ社製
ハイミランＡＭ７３３７：三井・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
ニュクレルＮ１０５０Ｈ：三井・デュポン・ポリケミカル社製、エチレン−メタクリル酸共重合体
ラバロンＴ３２２１Ｃ：三井化学社製、スチレン系エラストマー

Surlyn 8150: manufactured by DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Surlyn 9150: manufactured by DuPont, zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin polyamide 6: High Milan AM7337 manufactured by Toray Industries, Inc.・ DuPont Polychemical Co., Ltd., sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himira AM7329: Mitsui DuPont Polychemical Co., Ltd., zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin Nukurel N1050H: Mitsui・ DuPont Polychemical Co., Ltd., ethylene-methacrylic acid copolymer Lavalon T3221C: Mitsui Chemicals Co., Ltd., styrene elastomer

エラストランＸＮＹ７５Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー
エラストランＸＮＹ８２Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー
エラストランＸＮＹ８８Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー
エラストランＸＮＹ９５Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー
チヌビン７７０：ＢＡＳＦジャパン社製、ヒンダードアミン系光安定剤

Elastollan XNY75A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY82A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY88A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY95A: BASF Japan, thermoplastic Polyurethane elastomer Tinuvin 770: BASF Japan, hindered amine light stabilizer

3. Molding of the Intermediate Layer The intermediate layer covering the spherical core was formed by directly injection molding the intermediate layer composition obtained above on the spherical core obtained as described above. The upper and lower molds for molding have a hemispherical cavity and a hold pin that can advance and retract to support the sphere. At the time of forming the intermediate layer, the hold pin was protruded, the spherical core was inserted and held, the intermediate layer composition was poured into the mold, cooled, the mold was opened, and the sphere was taken out.

4). Formation of Reinforcing Layer A composition for a reinforcing layer (trade name “POLIN 750LE” manufactured by Shinto Paint Co., Ltd.) using a two-component curable epoxy resin as a base resin was prepared. The main agent contains 30 parts by mass of bisphenol A type epoxy resin and 70 parts by mass of solvent. The curing agent contains 40 parts by mass of modified polyamidoamine, 5 parts by mass of titanium oxide, and 55 parts by mass of solvent. The mass ratio of the main agent and the curing agent was 1/1. This reinforcing layer composition was applied to the surface of the intermediate layer-coated sphere with an air gun, and held at 23 ° C. for 12 hours to form a reinforcing layer. The thickness of the reinforcing layer was 7 μm.

5. Molding of Cover One pellet-like composition for a cover was put into each recess of the lower mold of a half-shell molding die and pressed to mold a 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. The intermediate layer-coated sphere on which the reinforcing layer was formed was concentrically covered with two half shells. The sphere and the half shell were put into a final mold having a large number of pimples on the cavity surface, and a cover 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. A large number of dimples having a reversed pimple shape were formed on the cover.

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 5 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 coating material A coating material was prepared by blending a curing agent with the main agent prepared above so that the NCO / OH ratios shown in Tables 6 and 7 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, the paint is dried in an oven at 40 ° C. for 24 hours, and the diameter is 42.7 mm. A golf ball having a mass of 45.6 g was obtained. The thickness of the coating film was 20 μm. The painting was performed while placing the golf ball body on a rotating body equipped with a prong, rotating the rotating body at 300 rpm, and blowing an air gun away from the golf ball body by a distance (7 cm) and moving it 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.

The evaluation results of the obtained golf ball are shown in Tables 6 and 7.

Golf ball no. 5 is the case where the difference (Mm−Mc) is 100 or less, but the flight distance on the driver shot is inferior. Golf ball no. Nos. 8, 22, and 23 are cases in which the ratio (Tm × Mm) / (Tc × Mc) is 7.5 or less, but the spin rate at the approach shot is low and the shot feeling is inferior. Golf ball no. 9 is a case where the intermediate layer is thinner than the cover (Tm <Tc), but the flight distance on the driver shot is inferior. Golf ball no. 12, 24, and 25 are cases where the 10% modulus of the coating film exceeds 100 kgf / cm ² and the ratio (Tc × Mc) / (Tp × Mp) is 2.4 or less. The spin rate is low and the feel at impact is inferior. Golf ball no. 15 is a case where a polyether diol having a number average molecular weight of 650 is used and the requirement of Mp ≦ 200 × X-75 is not satisfied, but the stain resistance is inferior.

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

1: golf ball, 2: spherical core, 21: inner core, 22: outer core, 3: intermediate layer, 4: reinforcing layer, 5: cover, 51: dimple, 52: land, 6: coating film

Claims (9)

A golf ball having a spherical core, an intermediate layer covering the spherical core, a golf ball body having a cover covering the intermediate layer, 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 Mp (kgf / cm ² ) of the coating film, 10% modulus Mm (kgf / cm ² ) of the intermediate layer, 10% modulus Mc (kgf / cm ² ) of the cover, and thickness of the coating film Tp (mm), the thickness Tm (mm) of the intermediate layer, the thickness Tc (mm) of the cover, and the hydroxyl group (OH group) of the polyol composition and the isocyanate group (NCO group of the polyisocyanate composition) ) Molar ratio (NCO / OH) X satisfies the following requirements.
Mp ≦ 200 × X-75
0.5 <X ≦ 1.20
Mp ≦ 100
Mm-Mc> 100
Tm>Tc> Tp
(Tm × Mm) / (Tc × Mc)> 7.5
(Tc × Mc) / (Tp × Mp)> 2.4 The absolute value (| Mp-Mc |) of the difference between the 10% modulus Mp (kgf / cm ² ) of the coating film and the 10% modulus Mc (kgf / cm ² ) of the cover is 65 or less. The golf ball described.   The golf ball according to claim 1, wherein a ratio of the volume Vc of the cover in the golf ball body is less than 10% by volume. The golf ball according to claim 1, wherein the cover has a 10% modulus Mc (kgf / cm ² ) of 20 or less. The golf ball according to claim 1, wherein the intermediate layer has a 10% modulus Mm (kgf / cm ² ) of 120 or more.   The golf ball according to claim 1, wherein a difference (Hs−Ho) between the surface hardness Hs and the center hardness Ho of the spherical core is 20 or more in terms of JIS-C hardness.   The golf ball according to claim 1, wherein the spherical core has at least one layer formed of a rubber composition containing a fatty acid and / or a metal salt thereof. The golf ball according to any one of claims 1 to 7, wherein a content of the polyether diol having the number average molecular weight of 800 to 3000 in the urethane polyol is 70% by mass or more. The golf ball according to claim 1, wherein the urethane polyol has a weight average molecular weight of 5,000 to 20,000.

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