JP2014014384A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball giving excellent controllability for an approach shot less than 40 yard, especially an approach shot from around a green (approximately from 10 yard to 20 yard).SOLUTION: A golf ball includes a core, a golf ball body having a cover of at least one layer covering the core, and a coating film provided on a surface of the golf ball body. The coating film has a storage elastic modulus (E') of 1.00×10dyn/cmor more and 1.00×10dyn/cmor less in a temperature range of 120°C-150°C, which is measured by a dynamic viscoelasticity device in a particular measurement condition, a loss tangent (tanδ) of 0.050 or more in 10°C, and a slab hardness of the cover in Shore D is 10 or more and 75 or less.

Description

  The present invention relates to a technique for improving the spin performance 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.

  Patent Documents 3 and 4 propose golf balls that are easy to stop by increasing the launch angle of the golf ball. Patent Document 3 discloses a golf ball having a golf ball main body and a paint layer covering the surface of the golf ball main body, wherein the resin component constituting the paint layer is cured with a polyamide-based curing agent. A golf ball characterized in that the coefficient of static friction of the golf ball is 0.22 or less is disclosed. Patent Document 4 discloses a golf ball having a golf ball body and a coating film covering the golf ball body, wherein the coating film contains metal particles.

Patent Document 5 proposes a golf ball with improved durability and squeeze resistance. The golf ball has a core, a cover, and one or more layers of paint formed on the cover. 50-65, a flexural modulus of 1000~2000kgf / cm ^2, the golf ball of at least the outermost layer of the 10% modulus and excellent durability, which is a 5~50kgf / cm ² of the paint disclosed Has been.

Patent Document 6 proposes a golf ball with improved spin retention without sacrificing the required properties of the coating film. In Patent Document 6, in a golf ball in which a coating film is formed on a core, at least one cover covering the core, and an outer surface of the cover, the coating film thickness is in the range of 25 μm to 125 μm. When the 50% modulus of the film is in the range of 5 MPa to 50 MPa, the thickness of the outermost layer cover is CL (mm), and the thickness of the coating film is PL (μm). A golf ball characterized in that R is in the range of 0.01 to 0.5 is disclosed.
R = PL / CL / 1000 (1)

JP 2011-67595 A JP 2011-217820 A JP 2006-75209 A JP 2006-75210 A JP 2000-288125 A JP 2003-265650 A

  Needless to say, not only the flight distance of driver shots but also the accuracy of approach shots are important in making scores for golf. However, little consideration has been given to the controllability of approach shots from around the green of less than 40 yards, especially 10 to 20 yards.

  The present invention has been made in view of the above circumstances, and provides a golf ball with improved controllability for approach shots of less than 40 yards, particularly approach shots from around the green (about 10 to 20 yards). Let it be an issue. Another object of the present invention is to provide a golf ball that has high controllability for both approach shots of less than 40 yards and approach shots of a distance of about 40 yards to 100 yards and that has an excellent shot feeling. It is another object of the present invention to provide a golf ball that has high controllability for approach shots of less than 40 yards and that can reduce the spin rate on driver shots.

  The present inventors have affected the mechanical properties of the coating film provided on the golf ball body on the controllability of approach shots less than 40 yards, especially approach shots from around the green (about 10 to 20 yards). As a result, the present invention has been completed.

That is, the golf ball of the present invention is a golf ball having a core, a golf ball main body comprising at least one cover covering the core, and a coating film provided on the surface of the golf ball main body. The storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. measured by a dynamic viscoelastic device under the following conditions is 1.00 × 10 ⁷ dyn / cm ² or more, 1.00 × 10 ⁸ dyn / cm ² or less, loss tangent (tan δ) at 10 ° C. is 0.050 or more, and the slab hardness of the cover is 10 to 75 in Shore D.
<Measurement conditions>
Measurement mode: Tensile Measurement temperature: -50 ° C to 150 ° C
Temperature increase rate: 4 ° C / min Excitation frequency: 10Hz
Measurement distortion: 0.1%

  When the present inventors measured the temperature change of the storage elastic modulus (E ') of a coating film using a dynamic viscoelastic device, there is almost no difference in storage elastic modulus (E') in a low temperature region. Even if it is a coating film, a difference arises in storage elastic modulus in a high temperature region of 120 ° C. to 150 ° C., and an approach shot in which the storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. is less than 40 yards. It has been found that this affects the spin performance. Moreover, the loss tangent (tan δ) of the coating film being large means that the given energy is converted into energy such as heat. The larger the loss tangent (tan δ), the less the approach shot of less than 40 yards. It has been found that spin performance is improved.

The coating film has an absolute value (| E ′) of a difference between a storage elastic modulus (E ′ ₁₂₀ ) measured at 120 ° C. using a dynamic viscoelastic apparatus and a storage elastic modulus (E ′ ₁₅₀ ) at 150 ° C. ₁₂₀₋ E ′ ₁₅₀ |) is preferably 2.00 × 10 ⁷ dyn / cm ² or less. 10% modulus of the coating film, 2 kgf / cm ² or more, preferably 160 kgf / cm ² or less, more preferably 2 kgf / cm ² or more and 130 kgf / cm ² or less.

  The slab hardness of the cover is preferably 10 or more and less than 55 in Shore D hardness. Further, the slab hardness of the cover is preferably from 55 to 75 in Shore D hardness.

  The base resin constituting the coating film is preferably a polyurethane obtained by reacting a polyol and a polyisocyanate, and more preferably a polyurethane obtained by reacting a polyol and two or more polyisocyanates. In the reaction between the polyol and the polyisocyanate, the molar ratio (NCO / OH) of the hydroxyl group (OH group) of the polyol and the isocyanate group (NCO group) of the polyisocyanate is 0.1 or more and 1.0 or less. Preferably there is.

  The polyisocyanate preferably contains a hexamethylene diisocyanate derivative and an isophorone diisocyanate derivative. The mixing ratio of the hexamethylene diisocyanate derivative and the isophorone diisocyanate derivative (HDI derivative / IPDI derivative) is preferably 80/20 to 50/50 in terms of mass ratio. The hexamethylene diisocyanate derivative preferably contains a burette modified product and an isocyanurate modified product of hexamethylene diisocyanate. The isophorone diisocyanate derivative preferably contains an isocyanurate-modified product of isophorone diisocyanate.

  The polyol preferably contains a urethane polyol obtained by reacting a polyol with a polyisocyanate. The polyol component constituting the urethane polyol contains a triol component and a diol component, and the mixing ratio of the triol component and the diol component (triol component / diol component) is 0.2 to 6.0 in terms of mass ratio. It is preferable that

  The golf ball body preferably has a two-piece structure, a three-piece structure, a four-piece structure, or a five-piece structure or more. The coefficient of friction of the golf ball calculated using a contact force tester is preferably 0.35 or more and 0.60 or less. The thickness of the coating film is preferably 10 μm or more and 50 μm or less.

  According to the present invention, a golf ball having high controllability in an approach shot of less than 40 yards, particularly an approach shot from around the green (about 10 to 20 yards) can be obtained. If the slab hardness of the cover is 10 or more and less than 55 in Shore D hardness, the controllability for both approach shots less than 40 yards and approach shots with a distance of about 40 yards to 100 yards is high, and the shot feel is excellent. Golf ball is obtained. Furthermore, when the slab hardness of the cover is 55 to 75 in terms of Shore D hardness, a golf ball with high controllability for approach shots of less than 40 yards and a reduced spin rate on driver shots can be obtained.

1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view illustrating a part of the golf ball in FIG. 1. 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. Paint No. A dynamic viscoelastic spectrum of A. Paint No. B dynamic viscoelastic spectrum. Paint No. C dynamic viscoelastic spectrum. Paint No. D dynamic viscoelastic spectrum. Paint No. Dynamic viscoelastic spectrum of S. The graph which shows the relationship between the storage elastic modulus (E ') of each coating material, and temperature. The graph which shows the relationship between the loss tangent (tan-delta) of each paint, and temperature.

The golf ball of the present invention is a golf ball having a core and a golf ball main body comprising at least one cover covering the core, and a coating film provided on the surface of the golf ball main body. The value of the storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. measured by a dynamic viscoelastic device under the following conditions is 1.00 × 10 ⁷ dyn / cm ² or more, 1.00 × 10 ^8. dyn / cm ² or less, loss tangent (tan δ) at 10 ° C. is 0.050 or more, and the slab hardness of the cover is 10 to 75 in Shore D.
<Measurement conditions>
Measurement mode: Tensile Measurement temperature: -50 ° C to 150 ° C
Temperature increase rate: 4 ° C / min Excitation frequency: 10Hz
Measurement distortion: 0.1%

The storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. measured using the dynamic viscoelastic device under the above conditions is 1.00 × 10 ⁷ dyn / cm ² or more, 1.00 × 10 ^8. A coating film of dyn / cm ² or less increases the spin rate of approach shots less than 40 yards. As a result, the golf ball of the present invention has high controllability for approach shots of less than 40 yards. From this viewpoint, the storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. is preferably 1.00 × 10 ⁸ dyn / cm ² or less, and more preferably 8.00 × 10 ⁷ dyn / cm ² or less. . Moreover, the storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. is preferably 1.00 × 10 ⁷ dyn / cm ² or more because the tackiness remains if the value is too low. 50 × 10 ⁷ dyn / cm ² or more is more preferable.

The coating film of the golf ball of the present invention preferably has a flat region where the storage elastic modulus (E ′) is substantially constant in the region of 120 ° C. to 150 ° C. when dynamic viscoelasticity is measured. In this respect, the storage modulus of 120 ° C. as measured with a dynamic viscoelastic acoustic device 'and _(120, storage elastic modulus of 0.99 ° C. (E E)' the absolute value of the difference between the _{150) (│E '120} -E ′ ₁₅₀ |) is preferably 2.00 × 10 ⁷ dyn / cm ² or less, and more preferably 1.00 × 10 ⁷ dyn / cm ² or less.

  The golf ball coating of the present invention has a loss tangent (tan δ) at 10 ° C. of 0.050 or more. By using a coating film having a loss tangent (tan δ) of 0.050 or more, it is possible to reduce the launch angle and increase the spin rate in approach shots of less than 40 yards. From this viewpoint, the loss tangent (tan δ) at 10 ° C. is more preferably 0.050 or more, and further preferably 0.060 or more. The upper limit of the loss tangent (tan δ) at 10 ° C. is 1.0.

  The dynamic viscoelasticity of the coating film is measured by preparing a film for measurement from the coating material forming the coating film. The production method and measurement method of the measurement film will be described later.

  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 not particularly limited as long as it satisfies the dynamic viscoelastic properties, but is preferably a polyurethane obtained by reacting a polyol and a polyisocyanate, A polyurethane obtained by reacting two or more polyisocyanates is more preferable. Polyurethane is easy to design dynamic viscoelastic properties and has excellent durability and adhesion. The storage elastic modulus (E ′) and loss tangent (tan δ) of the coating film can be set, for example, by appropriately selecting the type and blending ratio of polyol and polyisocyanate. In addition, the storage elastic modulus of the flat region can be controlled by, for example, the molecular weight or crosslink density of polyurethane.

  Examples of the polyol 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) , Condensation polyester polyols such as polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; urethane polyols; and acrylic polyols. . The polyol component may be used alone or in admixture of two or more.

  In the present invention, it is preferable to use urethane polyol as the polyol component. 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.

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.

  As the polyol component that can constitute the urethane polyol, those exemplified as the polyol can be used. In this invention, what contains a triol component and a diol component as a polyol component which comprises a urethane polyol is preferable. As the triol component, trimethylolpropane is preferable. As the diol component, polyoxytetramethylene glycol 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 acrylic polyol is an acrylic resin or an acrylic polymer having a plurality of hydroxyl groups in the molecule. For example, a (meth) acrylic monomer having a hydroxyl group and a (meth) acrylic monomer having no hydroxyl group are used. Obtained by copolymerization. In the present invention, (meth) acryl indicates acryl and / or methacryl.

  Examples of the (meth) acrylic monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, alkylene glycol mono Examples include (meth) acrylic acid esters having a hydroxyl group such as (meth) acrylate and polyalkylene glycol mono (meth) acrylate. These (meth) acrylic monomers having a hydroxyl group may be used alone or in combination of two or more.

  Examples of the (meth) acrylic monomer having no hydroxyl group include (meth) acrylic unsaturated carboxylic acid such as (meth) acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylic acid esters such as (meth) acrylic acid cyclohexyl, (meth) acrylic acid octyl, (meth) acrylic acid decyl; (meth) acrylonitrile, (meth) acrylic acid And the like. These (meth) acrylic monomers having no hydroxyl group may be used alone or in combination of two or more.

  The acrylic polyol may contain other monomer components having a hydroxyl group and / or other monomer components having no hydroxyl group other than the (meth) acrylic monomer. Examples of the other monomer component having a hydroxyl group include 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, and 2-methyl-3-buten-2-ol. , 2-methyl-2-buten-1-ol, 2-methyl-3-buten-1-ol, and unsaturated alcohols such as allyl alcohol. Examples of the other monomer component having no hydroxyl group include aromatic vinyl compounds such as styrene and α-methylstyrene; ethylenically unsaturated carboxylic acids such as maleic acid and itaconic acid; and the like. These other monomer components may be used alone or in combination of two or more.

  The hydroxyl value of the polyol is preferably 10 mgKOH / g or more, more preferably 15 mgKOH / g or more, further preferably 20 mgKOH / g or more, preferably 400 mgKOH / g or less, preferably 300 mgKOH / g or less, more preferably 200 mgKOH. / G or less, more 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.

  The polyol has a weight average molecular weight of preferably 500 or more, more preferably 550 or more, further preferably 600 or more, preferably 150,000 or less, more preferably 140,000 or less, and further preferably 130,000 or less. is there. When the weight average molecular weight of the polyol component is within the above range, the water resistance and impact resistance of the coating film can be improved. The weight-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) manufactured by Showa Denko KK Trademark) KF series "etc.).

  Specific examples of the polyol component include, for example, 121B manufactured by Waku Paint Co., Ltd., Nipponporan (registered trademark) 800, Nipponran 1100 manufactured by Nippon Polyurethane Industry Co., Ltd., Bernock (registered trademark) D6-627 manufactured by DIC, Barnock D8-436, Barnock D8-973, Barnock 11-408, Sumika Bayer Urethane Co., Ltd. Demosphen 650MPA, Demosfen 670, Demosphen 1150, Demosphen A160X, Harima Chemicals Hariacron 2000, Hariacron 8500H, Shinto Paint Co., Ltd. Porin (registered trademark) # 950 And so on.

  Next, polyisocyanate will be described. Examples of the polyisocyanate include compounds having at least two isocyanate groups.

Examples of the polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), and 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 polyisocyanates such as 4,4'-dicyclohexylmethane diisocyanate _(H 12 MDI), hydrogenated xylylene diisocyanate _(H 6 XDI), hexamethylene diisocyanate It includes derivatives of, and these polyisocyanates; HDI), isophorone diisocyanate (IPDI), alicyclic polyisocyanates or aliphatic polyisocyanates such as norbornene diisocyanate (NBDI). In the present invention, it is preferable to use two or more polyisocyanates as the polyisocyanate.

  Examples of the polyisocyanate derivatives include isocyanurates of diisocyanates; adducts obtained by reacting diisocyanates with low molecular weight triols such as trimethylolpropane or glycerin; modified allophanates; modified burettes, and the like. More preferably, the free diisocyanate is removed. The modified allophanate is, for example, a trifunctional polyisocyanate obtained by further reacting a diisocyanate with a urethane bond formed by reacting a diisocyanate and a low molecular weight diol. The modified burette is, for example, a trifunctional polyisocyanate having a burette bond represented by the following formula (1). The isocyanurate form of diisocyanate is, for example, a trifunctional polyisocyanate represented by the following formula (2). In formulas (1) and (2), R represents a residue obtained by removing an isocyanate group from diisocyanate.

  In the present invention, it is preferable to use a hexamethylene diisocyanate derivative and an isophorone diisocyanate derivative as the polyisocyanate. As the derivative of hexamethylene diisocyanate, it is preferable to use a burette modified product and an isocyanurate modified product of hexamethylene diisocyanate. As a derivative of isophorone diisocyanate, it is preferable to use an isocyanurate-modified product of isophorone diisocyanate.

  The mixing ratio of the derivative of hexamethylene diisocyanate and the derivative of isophorone diisocyanate (HDI derivative / IPDI derivative) is preferably 80/20 to 50/50, more preferably 65/35 to 55/45, in terms of mass ratio. The mixing ratio of the burette modified product and isocyanurate modified product of hexamethylene diisocyanate (burette modified product / isocyanurate modified product) is preferably 20/40 to 40/20, more preferably 25/35 to 35/25, in mass ratio. More preferred.

  The isocyanate group amount (NCO%) of the polyisocyanate is preferably 0.5% by mass or more, more preferably 1% by mass or more, further preferably 2% by mass or more, preferably 45% by mass or less, and preferably 40% by mass or less. More preferred is 35% by mass or less. 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 DIC's Barnock (registered trademark) D-800, Barnock DN-950, Barnock DN-955, Sumika Bayer Urethane's Death Module (registered trademark) N75MPA / X, Death Module N3300. , Death module L75 (C), Sumidur E21-1, Coronate (registered trademark) HX, Coronate HK manufactured by Nippon Polyurethane Industry Co., Ltd., Duranate (registered trademark) 24A-100, Duranate 21S-75E, Duranate TPA- 100, Duranate TKA-100, Degussa VESTANAT (registered trademark) T1890, and the like.

  In the reaction between the polyol and the polyisocyanate, the molar ratio (NCO group / OH group) of the hydroxyl group (OH group) of the polyol to the isocyanate group (NCO group) of the polyisocyanate is preferably 0.1 or more, 0.2 The above is more preferable. When the molar ratio (NCO group / OH group) is less than 0.1, the curing reaction is insufficient. 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 1.0 or less, more preferably 0.9 or less, and even more preferably 0.8 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 of the present invention is preferably formed from a paint containing a polyol and two or more polyisocyanates. Examples of the coating material include so-called two-component curable coating materials having a polyol as a main component and two or more polyisocyanates 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 coating using an air gun, the polyol component and the polyisocyanate component are supplied by respective pumps, continuously mixed with a line mixer placed immediately before the air gun, and the resulting mixture is spray coated. Alternatively, the polyol and the polyisocyanate may be separately spray-coated 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. In addition, the spin amount of the approach shot increases by increasing the film thickness. The film thickness of the coating film is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably less than 30 μm. If the film thickness exceeds 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 using a microscope (the Keyence company make, "VHX-1000"), for example. 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.

Martens hardness of the coating film provided on a surface of the golf ball body of the present invention is preferably 4.0mgf / μm ² or less, more preferably 3.5mgf / μm ^2, more preferably 3.0mgf / μm ² or less. Martens hardness can be measured by a method described later, and is suitable for measuring hardness in a minute region. This is because if the Martens hardness is 4.0 mgf / μm ² or less, the coating film becomes soft and the spin rate increases. Although the minimum of the said Martens hardness is not specifically limited, 0.01 mgf / micrometer < ² > is preferable. This is because if the Martens hardness is too low, the Martens hardness becomes too soft and the tackiness remains.

The 10% modulus of the coating film is preferably 160 kgf / cm ² or less, more preferably 130 kgf / cm ² or less, further preferably 110 kgf / cm ² or less. If the 10% modulus is 160 kgf / cm ² or less, the coating film is soft and the spin rate of approach shots is high. The lower limit of the 10% modulus of the coating is not particularly limited, but is preferably ² kgf / cm ^{2 and} more preferably 5 kgf / cm ² . This is because if the 10% modulus is too small, it becomes too soft, a tucking feeling remains, and the feeling becomes worse.

  The golf ball of the present invention is not particularly limited as long as it is a golf ball having a golf ball body and a coating film provided on the surface of the golf ball body. The structure of the golf ball main body is not particularly limited as long as the structure includes a core and at least one cover covering the core. As the structure of the golf ball main body, for example, a two-piece golf ball having a core and a single layer cover covering the core; a three-piece golf having a core, an intermediate layer covering the core, and a cover covering the intermediate layer Four-piece golf ball; Multi-piece golf ball greater than five-piece golf ball, or thread-wound golf ball. 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 2 according to an embodiment of the present invention. The golf ball 2 includes a spherical core 104, an intermediate layer 106 that covers the spherical core 104, and a cover 112 that covers the intermediate layer 106. A large number of dimples 114 are formed on the surface of the cover 112. Of the surface of the golf ball, a portion other than the dimple 114 is a land 116. This golf ball has a paint layer and a mark layer on the outside of the cover, but these layers are not shown.

  In the golf ball of the present invention, the slab hardness of the cover is Shore D hardness of 10 or more, preferably 15 or more, more preferably 20 or more, and 75 or less, preferably 73 or less, more preferably 70 or less. . If the cover has a Shore D hardness of 75 or less, the spin rate on approach shots at a distance of about 40 yards to 100 yards increases, and controllability is improved. The slab hardness of the cover is a slab hardness measured by molding the cover composition forming the cover into a sheet shape.

  Further, in the case of a spin-type golf ball that emphasizes controllability, the slab hardness of the cover is preferably Shore D hardness of 10 or more, more preferably 15 or more, still more preferably 20 or more, and preferably less than 55. More preferably, it is 50 or less, More preferably, it is 45 or less. If the slab hardness of the cover composition is less than 55 in Shore D hardness, the spin rate of approach shots at a distance of 40 yards to 100 yards will be high, it will be easy to stop on the green, and the shot feel will be good It becomes. Further, by setting the slab hardness to 10 or more, the scratch resistance is improved.

  On the other hand, in the case of a distance type golf ball that places importance on the flight distance, the slab hardness of the cover composition is preferably 55 or more, more preferably 58 or more, further preferably 60 or more, and 75 or less in Shore D hardness. More preferably, it is 73 or less, More preferably, it is 70 or less. By setting the slab hardness of the cover to 55 or more, a golf ball having a high launch angle and a low spin can be obtained in a driver shot, a long shot, and a middle iron shot, and the flight distance is increased. Further, by setting the slab hardness of the cover composition to 75 or less, a golf ball having excellent durability can be obtained.

  The cover material constituting the golf ball cover of the present invention is not particularly limited. For example, urethane resin such as ionomer resin, polyester resin, thermoplastic urethane resin or two-component curable urethane resin, polyamide resin, etc. Various types of resins, thermoplastic polyamide elastomers marketed by Arkema Co., Ltd. under the trade name "Pebax (registered trademark)" (for example, "Pebax 2533"), trade name "Hytrel (registered trademark)" by Toray DuPont Co., Ltd. ) (For example, “Hytrel 3548”, “Hytrel 4047”) ”, commercially available from BASF Japan, trade name“ Elastollan (registered trademark) ”(for example,“ Elastollan XNY90A ”,“ "Elastolan XNY97A", "Erastra XNY585 ")", a thermoplastic polyurethane elastomer commercially available under the trade name "Lavalon (registered trademark)" from Mitsubishi Chemical Corporation, or a heat commercially available under the trade name "Primalloy" Examples thereof include a plastic polyester elastomer. You may use the said cover material individually or in mixture of 2 or more types.

  As described above, when the slab hardness of the cover is 10 or more and less than 55 in Shore D hardness, it is preferable that the cover composition contains polyurethane. In the case of using polyurethane, the content of polyurethane in the resin component of the cover composition is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, and 90% by mass or more. Is particularly preferred.

  The polyurethane is a polymer having a plurality of urethane bonds in the molecular chain, and is obtained, for example, by reacting a polyol and a polyisocyanate. If necessary, a chain extension reaction may be performed with a chain extender such as a low molecular weight polyol or a low molecular weight polyamine.

The polyisocyanate component constituting the polyurethane 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 mixture (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 p-phenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate _(H 12 MDI), hydrogen added Xylylene diisocyanate _(H 6 XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1 kind of cycloaliphatic polyisocyanates or aliphatic polyisocyanates such as norbornene diisocyanate (NBDI), or, two A mixture of the above.

From the viewpoint of improving the scratch resistance, it is preferable to use an aromatic polyisocyanate as the polyisocyanate component of the polyurethane. By using the aromatic polyisocyanate, the mechanical properties of the resulting polyurethane are improved, and a cover having excellent scratch resistance can be obtained. From the viewpoint of improving weather resistance, non-yellowing polyisocyanate (TMXDI, XDI, HDI, H ₆ XDI, IPDI, H ₁₂ MDI, NBDI, etc.) may be used as the polyisocyanate component of polyurethane. Preferably, more preferably 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI) is used. This is because 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI) has a rigid structure, the mechanical properties of the resulting polyurethane are improved, and a cover having excellent scratch resistance can be obtained.

  The polyol component constituting the polyurethane is not particularly limited as long as it has a plurality of hydroxyl groups, and examples thereof include a low molecular weight polyol used as a chain extender and a polymer polyol constituting a soft segment. . 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, 1,6-hexanediol; glycerin, trimethylol Examples include triols such as propane and hexanetriol. Examples of the polymer polyol include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), polyoxytetramethylene glycol (PTMG); polyethylene adipate (PEA), polybutylene adipate ( PBA), condensed polyester polyols such as polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols, etc. It may be a mixture of at least two or more of the polyols described above. The polyol component constituting the polyurethane used in the present invention is preferably polyoxytetramethylene glycol.

  The number average molecular weight of the polymer polyol is not particularly limited, but is preferably 400 or more, and more preferably 1,000 or more, for example. This is because if the number average molecular weight of the polymer polyol is too small, the resulting polyurethane becomes hard and the feel at impact of the golf ball decreases. The upper limit of the number average molecular weight of the polymer polyol is not particularly limited, but is 10,000 or less, more preferably 8,000 or less.

  The polyamine that can constitute the polyurethane as needed is not particularly limited as long as it has at least two amino groups. Examples of the polyamine include aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine and hexamethylenediamine, alicyclic polyamines such as isophoronediamine and piperazine, and phenylenediamine, toluenediamine, diethyltoluenediamine and dimethylthiotoluene. Aromatic polyamines such as diamine, xylylenediamine, and diphenylmethanediamine are exemplified.

  As described above, when the slab hardness of the cover is 55 to 75 in Shore D hardness, the cover composition preferably contains an ionomer resin. In the case of using an ionomer resin, the content of the ionomer resin in the resin component of the cover composition is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more.

  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.

  Specific examples of the ionomer resin are exemplified by trade names, such as “Himilan (registered trademark)” (for example, Himilan 1555 (Na), Himilan 1557 (Zn), commercially available from Mitsui DuPont Polychemical Co., Ltd., High Milan 1605 (Na), High Milan 1706 (Zn), High Milan 1707 (Na), High Milan AM 3711 (Mg) and the like are listed. Examples of the terpolymer ionomer resins include High Milan 1856 (Na) and High Milan 1855 (Zn). ) ".

  Further, ionomer resins commercially available from DuPont include “Surlyn (registered trademark)” (for example, Surlyn 8945 (Na), Surlyn 9945 (Zn), Surlyn 8140 (Na), Surlyn 8150 (Na), Surlyn 9120 (Zn), Surlyn 9150 (Zn), Surlyn 6910 (Mg), Surlyn 6120 (Mg), Surlyn 7930 (Li), Surlyn 7940 (Li), Surlyn AD8546 (Li) and the like, and terpolymers Examples of the ionomer resin include Surlyn 8120 (Na), Surlyn 8320 (Na), Surlyn 9320 (Zn), Surlyn 6320 (Mg), HPF1000 (Mg), HPF2000 (Mg), and the like.

  Examples of ionomer resins commercially available from ExxonMobil Chemical Co., Ltd. include “Iotek (registered trademark)” (for example, Iotech 8000 (Na), Iotech 8030 (Na), Iotech 7010 (Zn), Iotech 7030 ( Zn) and the like, and examples of the ternary copolymer ionomer resin include Iotech 7510 (Zn) and Iotech 7520 (Zn)).

  Note that Na, Zn, Li, Mg, and the like described in parentheses after the trade name of the ionomer resin indicate the metal species of these neutralized metal ions. The ionomer resins may be used alone or in admixture of two or more.

  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.

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

  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 occupation ratio is preferably 60% or more, more preferably 63% or more, further preferably 66% or more, preferably 95% or less, more preferably 92% or less, and 89% or less. Further preferred. When the occupation ratio becomes too high, the contribution of the coating film to the friction coefficient described later 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 = (Dm / 2) ² · π (Dm: Dimple diameter)

  FIG. 2 shows a cross section along a plane passing through the center of the dimple 114 and the center of the golf ball 2. The vertical direction in FIG. 2 is the depth direction of the dimple 114. In FIG. 2, what is indicated by a two-dot chain line 118 is a virtual sphere. The surface of the phantom sphere is the surface of the golf ball 2 when it is assumed that the dimple 114 does not exist. The dimple 114 is recessed from the surface of the phantom sphere. Land 116 coincides with the surface of the phantom sphere. In the present embodiment, the cross-sectional shape of the dimple 114 is substantially an arc.

  In FIG. 2, the diameter of the dimple 114 is indicated by a double arrow Dm. The diameter Dm is the distance between one contact point Ed and the other contact point Ed when a common tangent line Tg is drawn on both sides of the dimple 114. The contact point Ed is also the edge of the dimple 114. The edge Ed defines the contour of the dimple 114. In FIG. 2, what is indicated by a double-headed arrow Dp is the depth of the dimple 114. The depth Dp is the distance between the deepest part of the dimple 114 and the tangent line Tg.

  The diameter Dm of the dimple is preferably 2.0 mm or greater and 6.0 mm or less. Dimples having a diameter Dm of 2.0 mm or more contribute to turbulence. In this respect, the diameter Dm is more preferably equal to or greater than 2.2 mm, and particularly preferably equal to or greater than 2.4 mm. Dimples having a diameter Dm of 6.0 mm or less do not impair the essence of the golf ball 2 that is substantially a sphere. In this respect, the diameter Dm is more preferably 5.8 mm or less, and particularly preferably 5.6 mm or less.

In FIG. 2, what is indicated by an arrow CR is the radius of curvature of the dimple 114. The curvature radius CR is calculated by the following mathematical formula (1).
^{CR = (Dp 2 + Dm 2} /4) / (2 × Dp) (1)
Even in the case of the dimple 114 whose cross-sectional shape is not an arc, the curvature radius CR is approximately calculated based on the above formula (1).

  In light of achieving a sufficient occupation ratio, the total number of dimples is preferably 300 or more, more preferably 310 or more, and particularly preferably 320 or more. From the viewpoint that individual dimples can contribute to turbulence, the total number is preferably 500 or less, more preferably 490 or less, and particularly preferably 480 or less.

In the present invention, “dimple volume” means the volume of a portion surrounded by a plane including the outline of the dimple and the surface of the dimple. From the viewpoint of rising of the golf ball 2 is suppressed, the total volume of the dimples is preferably 250 mm ³ or more, more preferably 260 mm ³ or more, 270 mm ³ or more is particularly preferable. In view of dropping of the golf ball 2 is suppressed, the total volume is preferably 450 mm ³ or less, more preferably 440 mm ³ or less, 430 mm ³ or less is particularly preferred.

  In light of suppression of hops in the golf ball 2, the depth Dp of the dimple 114 is preferably 0.05 mm or more, more preferably 0.08 mm or more, and particularly preferably 0.10 mm or more. In light of suppression of dropping of the golf ball 2, the depth Dp is preferably equal to or less than 0.60 mm, more preferably equal to or less than 0.45 mm, and particularly preferably equal to or less than 0.40 mm.

  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 used for the wound golf ball, the two-piece golf ball, and the multi-piece golf ball 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 amount of the carboxylic acid and / or salt thereof is preferably 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the 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. The core may be a single-layer core or a two-layer core composed of a center and an envelope layer.

  When the golf ball of the present invention is a 3-piece, 4-piece golf ball, or multi-piece golf ball of 5 pieces or more, the intermediate layer provided between the core and the outermost cover is, for example, a polyurethane resin. And 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. 3 is a contact force tester for measuring the friction coefficient. FIG. 4 is an enlarged cross-sectional view of the collision plate 4 that causes the golf ball to collide.

  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 19 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. 4 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. 5 shows a time history of the normal force Fn and the shear force Ft received by the striking surface 3 at the time of collision between the golf ball 2 and the striking surface 3 under one condition measured by the contact force testing machine 1.

  FIG. 5 is a graph showing an example of Fn (t) and Ft (t) measured by the measuring apparatus of FIGS. 3 and 4. In FIG. 5, a point P <b> 0 is a point at which the pressure sensor 4 b starts to sense force, and substantially corresponds to the time when the collision between the striking surface 3 and the golf ball 2 starts. 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) Slab hardness (Shore D hardness)
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. 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) Measurement of friction coefficient The friction coefficient of the golf ball was measured using the contact force tester shown in FIGS.
1. Specification 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. 6 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 Pulse counter board PCI-6101 (manufactured by Interface Corporation) 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. 6, a groove structure of a sand wedge CG-15 manufactured by Cleveland is reproduced on the striking surface 3 (see FIG. 3) of the collision plate 4. As shown in FIG. 6A, the striking surface 3 is provided with a plurality of small grooves on the surface between the large grooves (zip grooves) and the large grooves (zip grooves). FIG. 6B is an enlarged view of the 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 were measured using a surface roughness measuring machine (“SJ-301” manufactured by Mitutoyo Corporation) under the measurement conditions of measurement length = 2.5 mm and cut-off value = 2.5 mm. To do.

2. Measurement procedure The coefficient of friction was measured by the following method.
(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.
(D) The initial velocity of the golf ball is measured from the preset distance between the sensor S1 and the sensor S2 (see FIG. 3) and the golf ball shielding time difference therebetween. The initial velocity of the golf ball was adjusted to 19 m / s.
(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.

3. Measurement Results FIG. 7 shows an example of the results measured by the test apparatus and measurement procedure. From FIG. 7, 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.

(3) Martens hardness of the coating film Measured using a nanoindenter “ENT-2100” manufactured by Elionix.
The measurement conditions are as follows.
Load F: 20 mgf
Berkovich indenter angle α: 65.03 °
Barkovic indenter material: SiO ₂
Based on the indentation depth h and the indenter angle α, the area As (h) is calculated by the following mathematical formula.
As (h) = 3 × 3 ^1/2 × tan α / cos α × h ²
Based on the load F and the area As (h), the Martens hardness is calculated by the following mathematical formula.
Martens hardness = F / As (h)
Measurement sample: 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 sheet having a thickness of 100 μm and used for measurement.

(4) 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 is punched into a dumbbell shape to produce a test piece, and the physical properties of the coating film are measured using a tensile test measuring device (manufactured by Shimadzu Corporation), and the modulus at 10% elongation is calculated. did.
Film thickness of test piece: 0.05mm
Tensile speed: 50 mm / min

(5) Measurement of dynamic viscoelasticity The storage elastic modulus E ′ (dyn / cm ² ) and loss tangent (tan δ) of the coating film were measured under the following conditions.
Apparatus: Dynamic viscoelasticity measuring apparatus Rheogel-E4000 manufactured by UBM Co., Ltd.
Measurement sample: The paint containing the main agent and the curing agent was dried and cured at 40 ° C. for 4 hours to prepare a coating film having a thickness of 0.11 mm to 0.14 mm. A sample piece was cut out from this coating film so as to have a width of 4 mm and a distance between clamps of 20 mm.
Measurement mode: Tensile Measurement temperature: -50 ° C to 150 ° C
Temperature rise rate: 4 ° C / min Measurement data capture interval: 4 ° C
Excitation frequency: 10 Hz
Measurement distortion: 0.1%
As the storage elastic modulus E ′ ₁₂₀ at 120 ° C., the measured data was taken at 4 ° C. intervals, and the value of the storage elastic modulus at which the data was first acquired at a measurement temperature of 120 ° C. or higher was adopted. For the storage elastic modulus E ′ ₁₅₀ of 150 ° C., the value of the storage elastic modulus at which the data was last taken at the measurement temperature of 150 ° C. or less was adopted at the intervals of 4 ° C. for the measurement data. For the loss tangent (tan δ) at 10 ° C., the measurement data was taken at 4 ° C. intervals, and the value of the loss tangent at which the data was first taken at a measurement temperature of 10 ° C. or higher was adopted.

(6) Spin amount of approach shot (21 m / s: equivalent to 40 yards to 100 yards shot)
Sand Wedge (CG15 Forged Wedge (52 °) manufactured by Cleveland Golf Co., Ltd.) is attached to TrueTemper's swing robot M / C, and a golf ball is hit at a head speed of 21 m / sec. The shot golf ball is photographed continuously. As a result, the spin rate (rpm) was measured. The measurement was performed 10 times for each golf ball, and the average value was defined as the spin amount. Golf ball No. The spin amount of 1 to 18 is the golf ball No. The difference from the spin amount of 11 is shown.

(7) Approach shot spin rate (10 m / s: equivalent to shots less than 40 yards)
Sand Wedge (CG15 Forged Wedge (52 °) manufactured by Cleveland Golf Co., Ltd.) is attached to a swing robot M / C manufactured by True Temper, and a golf ball is hit at a head speed of 10 m / sec, and the shot golf ball is photographed continuously. As a result, the spin rate (rpm) was measured. The measurement was performed 10 times for each golf ball, and the average value was defined as the spin amount. As for the launch angle, a one-dimensional CCD sensor was used to measure a shadow when a ball passed through a screen of light from a linear laser light source provided in front of the swing direction of the swing robot M / C. Golf ball No. The spin amount and launch angle of 1 to 18 were measured according to golf ball No. Golf ball no. The spin amount and launch angle of 19 to 34 are the same as those of golf ball no. It is shown by the difference from 26.

(8) Spin rate of driver shot A driver equipped with a titanium head (Dunlop Sports, XXIO S Loft 10.0 °) is attached to a swing robot M / C manufactured by Trutemper, and golf is played at a head speed of 45 m / sec. The ball was hit and the spin amount of the golf ball immediately after hitting was 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. Note that the spin amount of the golf ball immediately after hitting was measured by taking continuous photographs of the hit golf ball. Golf ball No. The spin amount of 19 to 34 is the golf ball No. It is shown by the difference from 26.

(9) Hit feeling A real 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.
◎: 9 or more ○: 6 to 8 △: 3 to 5 ×: 2 or less

[Production of golf balls]
(1) Preparation of center composition Materials having the composition shown in Table 1 were kneaded to prepare a center composition.

ポリブタジエン：ＪＳＲ社製、「ＢＲ７３０（ハイシスポリブタジエン）」
ＺＮＤＡ−９０Ｓ：日本蒸溜工業社製、アクリル酸亜鉛（１０質量％ステアリン酸亜鉛コーティング品）
サンセラーＳＲ：三新化学工業社製、アクリル酸亜鉛（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」
ジフェニルジスルフィド：住友精化社製
２−チオナフトール：東京化成工業社
ビス（ペンタブロモフェニル）ジスルフィド：川口化学工業社
オクタン酸亜鉛：三津和化学薬品社
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: “BR730 (High cis polybutadiene)” manufactured by JSR Corporation
ZNDA-90S: manufactured by Nippon Distilled Industries Co., Ltd., zinc acrylate (10% by weight zinc stearate coated product)
Suncellor SR: Sanshin Chemical Industry Co., Ltd., zinc acrylate (10% by mass stearic acid coating product)
Zinc oxide: Toho Zinc Co., Ltd.
Barium sulfate: Sakai Chemical Co., Ltd. “Barium sulfate BD”
Diphenyl disulfide: Sumitomo Seika Chemical Co., Ltd. 2-thionaphthol: Tokyo Chemical Industry Co., Ltd. Bis (pentabromophenyl) disulfide: Kawaguchi Chemical Co., Ltd. Zinc Octanoate: Mitsuwa Chemicals Co., Ltd. Dicumyl peroxide: NOF Corporation, "Park Mill" (Registered trademark) D "

(2) Preparation of intermediate layer composition and cover composition The materials shown in Tables 2 and 3 were mixed with a twin-screw kneading extruder to form a pellet-like intermediate layer composition and cover. A composition was prepared. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D = 35.

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
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系アイオノマー樹脂
エラストランＸＮＹ９７Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー
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
チヌビン７７０：ＢＡＳＦジャパン社製、ヒンダードアミン系安定剤

Surlyn 8945: DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himiran AM 7329: Mitsui DuPont Polychemical, zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himiran AM7337: Mitsui DuPont polychemical Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Elastollan XNY97A: BASF Japan, thermoplastic polyurethane elastomer Lavalon T3221C: Mitsubishi Chemical, thermoplastic polystyrene elastomer Tinuvin 770: BASF Japan, hindered amine System stabilizer

エラストランＸＮＹ７３Ａ：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ＸＮＹ８０Ａ：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ＸＮＹ８３Ａ：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ＸＮＹ８５Ａ：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
ハイミラン１７０６：三井・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
ハイミラン１５５５：三井・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
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
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系アイオノマー樹脂
ノバミッドＳＴ２２０：三菱エンジニアリングプラスチックス社製、ポリアミド樹脂（高
衝撃グレード、曲げ弾性率：２０００ＭＰａ）
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
チヌビン７７０：ＢＡＳＦジャパン社製、ヒンダードアミン系安定剤

Elastollan XNY73A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY75A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY80A: BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY82A: BASF Japan, thermoplastic Polyurethane elastomer Elastollan XNY83A: manufactured by BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY85A: manufactured by BASF Japan, thermoplastic polyurethane elastomer Elastollan XNY95A: manufactured by BASF Japan, thermoplastic polyurethane elastomer HiMilan 1706: Mitsui DuPont Polychemical Zinc ion neutralized ethylene-methacrylic acid copolymer Iono Resin High Milan 1555: Mitsui-DuPont Polychemical Co., Ltd., sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Surlyn 8945: DuPont, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himira AM 7329: Mitsui・ Dupont Polychemical Co., Ltd., zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himira AM7337: Mitsui DuPont Polychemical Co., Ltd., sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Novamid ST220: Mitsubishi Engineering Plastics Polyamide resin (high impact grade, flexural modulus: 2000 MPa)
Nukurel N1050H: Mitsui DuPont Polychemical Co., Ltd., ethylene-methacrylic acid copolymer Tinuvin 770: BASF Japan Co., Ltd., hindered amine stabilizer

(3) Production of Golf Ball Body (3-1) Golf Ball No. 1-16, 19-32
Center composition No. A was kneaded and heated and pressed at 170 ° C. for 20 minutes in an upper and lower mold having a hemispherical cavity to obtain a spherical center having a diameter of 39.3 mm.

  Intermediate layer composition No. obtained above. A was directly injection molded on the spherical center obtained as described above, thereby forming an intermediate layer (thickness: 1.0 mm) covering the center. The upper and lower molds for molding have a hemispherical cavity and a hold pin that can move back and forth to support the spherical center. 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. The mold was opened after cooling.

  For compression molding of the half shell, the obtained pellet-shaped cover composition (shown in Tables 5 to 8) is charged one by one for each concave portion of the lower mold of the half shell molding die, and pressed to form a half shell. Was molded. 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 obtained above was concentrically covered with the two half shells obtained above, 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.

(3-2) Golf Ball No. 17
Center composition No. B was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity, and heated at 170 ° C. for 25 minutes to obtain a spherical center having a diameter of 39.5 mm. A spherical center was introduced into the mold, and the intermediate layer composition no. B was injected around the spherical center by an injection molding method to form a first intermediate layer (thickness: 1.0 mm). Intermediate layer composition No. obtained above. From C, a half shell was formed by compression molding, and a second intermediate layer (thickness 0.3 mm) covering the first intermediate layer was formed from this half shell by compression molding. Cover composition No. From k, a half shell was molded by a compression molding method, and a cover (thickness 0.3 mm) covering the second intermediate layer was formed from the half shell by a compression molding method.

(3-3) Golf Ball No. 18
Center composition No. C was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at a temperature of 170 ° C. for 25 minutes to obtain a spherical center having a diameter of 15 mm. Center composition No. obtained above. From D, a half shell was formed by compression molding, and an envelope layer (thickness 12.25 mm) covering the spherical center was formed from this half shell by compression molding. Subsequently, the golf ball No. Similarly to 17, a first intermediate layer (thickness 1.0 mm), a second intermediate layer (thickness 0.3 mm) and a cover (thickness 0.3 mm) were formed.

(3-4) Golf Ball No. 33
Center composition No. E was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at 170 ° C. for 25 minutes to obtain a spherical center having a diameter of 37.9 mm. A spherical center was introduced into the mold, and the intermediate layer composition no. D was injected around the spherical center by an injection molding method to form a first intermediate layer (thickness 0.8 mm). Furthermore, composition No. for intermediate | middle layer obtained above was used. E was injected around the first intermediate layer by injection molding to form a second intermediate layer (thickness 0.8 mm). Finally, the cover composition No. obtained above. l was injected around the second intermediate layer by injection molding to form a cover (thickness 0.8 mm).

(3-5) Golf Ball No. 34
Center composition No. E was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at 170 ° C. for 25 minutes to obtain a spherical center having a diameter of 36.3 mm. A spherical center was introduced into the mold, and the intermediate layer composition no. D was injected around the spherical center by an injection molding method to form a first intermediate layer (thickness 0.8 mm). Next, the intermediate layer composition No. obtained above was obtained. E was injected around the first intermediate layer by injection molding to form a second intermediate layer (thickness 0.8 mm). Furthermore, composition No. for intermediate | middle layer obtained above was used. F was injected around the second intermediate layer by an injection molding method to form a third intermediate layer (thickness 0.8 mm). Finally, the cover composition No. obtained above. l was injected around the third intermediate layer by injection molding to form a cover (thickness 0.8 mm).

(4) Preparation of paint A paint was prepared by blending the polyol shown in Table 4 and polyisocyanate. In addition, the main ingredient was adjusted so that the density | concentration of a polyol component might be 30 mass% using the mixed solvent of methyl ethyl ketone, n-butyl acetate, and toluene. The curing agent was adjusted so that the concentration of the polyisocyanate component was 60% by mass using a mixed solvent of methyl ethyl ketone and toluene as a solvent. About the obtained coating material, the physical property of the coating film was measured and it showed to Tables 5-8. Moreover, the dynamic viscoelastic spectrum about each coating material is shown in FIGS. 9-13, the relationship between the storage elastic modulus (E ') and temperature of each coating material is shown in FIG. 14, the loss tangent (tan δ) of each coating material and temperature. The relationship is shown in FIG.

The raw materials used in Table 4 are as follows.
Prin # 950 manufactured by Shinto Paint Co., Ltd .: urethane polyol curing agent HDI (hexamethylene diisocyanate) comprising a hydroxyl value of 128 mgKOH / g, a polyol component (trimethylolpropane, polyoxytetramethylene glycol) and a polyisocyanate component (isophorone diisocyanate) ) Modified burette: "Duranate (registered trademark) 21S-75E" manufactured by Asahi Kasei Chemicals Corporation (NCO content: 15.5%)
Modified isocyanurate of HDI (hexamethylene diisocyanate): “Duranate TKA-100” manufactured by Asahi Kasei Chemicals Corporation (NCO content: 21.7%)
Isocyanurate of IPDI (isophorone diisocyanate): manufactured by Degussa, “VESTANAT (registered trademark) T1890” (NCO content: 12.0%)

(5) Formation of coating film After the surface of the golf ball body obtained in (3) is sandblasted and marked, the paint is applied with a spray gun and dried in an oven at 40 ° C. for 24 hours. A golf ball having a diameter of 42.7 mm was obtained. The thickness of the coating film was determined according to Golf Ball No. 1-13, 17-29, 32-34 are 20 micrometers, golf ball No.1. 14 and 30 are 30 μm, golf ball No. 15 and 31 were 40 micrometers. The coating was performed by placing the golf ball body on the rotating body shown in FIG. 8, rotating the rotating body at 300 rpm, and blowing the air gun away from the golf ball body by a distance of 7 cm and moving it up and down. . The interval of each overcoating was 1.0 second. The air gun spraying conditions were as follows: spraying 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: 65% or less Painted. The result evaluated about the obtained golf ball was collectively shown in Tables 5-8.

From the results of Tables 5 to 8, the storage elastic modulus (E ′) in the temperature range of 120 ° C. to 150 ° C. of the coating film is 1.00 × 10 ⁷ dyn / cm ² or more, 1.00 × 10 ⁸ dyn / cm. ^A golf ball having a loss tangent (tan δ) at 10 ° C. of 0.050 or more and a cover slab hardness of 10 or more and 75 or less is approach shot of less than 40 yards, particularly around the green (10-20) It can be seen that the controllability in approach shots from the yard level is improved.

  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, 21: Rotating body, 23a-23c: Prong, 25: Air gun, 104: Inner core, 106: Outer core, 107: Spherical core, 108: Intermediate layer, 110: Reinforcement layer, 112: Cover, 114: Dimple, 116: Land

Claims (21)

A golf ball comprising a golf ball body comprising a core and at least one cover covering the core, and a coating film provided on the surface of the golf ball body,
The coating film has a storage elastic modulus (E ′) in a temperature range of 120 ° C. to 150 ° C. measured by a dynamic viscoelasticity device under the following conditions, 1.00 × 10 ⁷ dyn / cm ² or more, 1.00 × 10 ⁸ dyn / cm ² or less, and loss tangent (tan δ) at 10 ° C. is 0.050 or more,
A golf ball having a slab hardness of 10 to 75 in Shore D.
<Measurement conditions>
Measurement mode: Tensile Measurement temperature: -50 ° C to 150 ° C
Temperature increase rate: 4 ° C / min Excitation frequency: 10Hz
Measurement distortion: 0.1% The absolute value of the difference between the storage elastic modulus at 120 ° C. (E ′ ₁₂₀ ) measured using a dynamic viscoelastic device and the storage elastic modulus at 150 ° C. (E ′ ₁₅₀ ) (| E ′ ₁₂₀ −E ′ ₁₅₀ The golf ball according to claim 1, wherein |) is 2.00 × 10 ⁷ dyn / cm ² or less.   The golf ball according to claim 1, wherein the slab hardness of the cover is 10 or more and less than 55 in Shore D hardness.   The golf ball according to claim 1, wherein the cover has a slab hardness of 55 to 75 in Shore D hardness.   The golf ball according to any one of claims 1 to 4, wherein the base resin constituting the coating film is a polyurethane obtained by reacting a polyol and a polyisocyanate.   The golf ball according to claim 1, wherein the base resin constituting the coating film is polyurethane obtained by reacting a polyol with two or more polyisocyanates.   In the reaction between the polyol and the polyisocyanate, the molar ratio (NCO / OH) of the hydroxyl group (OH group) of the polyol and the isocyanate group (NCO group) of the polyisocyanate is 0.1 or more and 1.0 or less. The golf ball according to claim 5 or 6.   The golf ball according to claim 5, wherein the polyisocyanate contains a derivative of hexamethylene diisocyanate and a derivative of isophorone diisocyanate.   The golf ball according to claim 8, wherein a mixing ratio of the hexamethylene diisocyanate derivative and the isophorone diisocyanate derivative (HDI derivative / IPDI derivative) is 80/20 to 50/50 in mass ratio.   The golf ball according to claim 8, wherein the derivative of hexamethylene diisocyanate contains a burette modified product and an isocyanurate modified product of hexamethylene diisocyanate.   The golf ball according to claim 8, wherein the isophorone diisocyanate derivative contains an isocyanurate-modified product of isophorone diisocyanate.   The golf ball according to claim 5, wherein the polyol contains a urethane polyol obtained by reacting a polyol with a polyisocyanate.   The polyol component constituting the urethane polyol contains a triol component and a diol component, and the mixing ratio of the triol component and the diol component (triol component / diol component) is 0.2 to 6.0 in terms of mass ratio. The golf ball according to claim 12, wherein The 10% modulus of the coating film, 2 kgf / cm ² or more, the golf ball according to any one of 160 kgf / cm ² or less is claims 1-13. The 10% modulus of the coating, the golf ball according to claim 14 2 kgf / cm ² or more and 130 kgf / cm ² or less.   The golf ball according to claim 1, wherein the golf ball main body has a two-piece structure.   The golf ball according to claim 1, wherein the golf ball main body has a three-piece structure.   The golf ball according to claim 1, wherein the golf ball main body has a four-piece structure.   The golf ball according to claim 1, wherein the golf ball main body has a structure of five pieces or more.   The golf ball according to claim 1, wherein a friction coefficient of the golf ball calculated by 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 10 μm or more and 50 μm or less.

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