JP7339766B2 - Golf ball - Google Patents

Description

The present invention relates to golf balls having coatings.

Conventionally, a golf ball has a coating film formed on the surface of the golf ball body. This coating film contributes to the performance, quality and appearance of the golf ball. It has been proposed to impart water repellency to such a coating film to prevent water from adhering to the surface of the golf ball when it is used in rainy weather or the like.

For example, Patent Document 1 discloses a core, a cover provided outside the core and formed with dimples, and a cover provided outside the cover and made of a material having a contact angle of 90° or more. Patent Document 1 (Claim 1, paragraph 0042) describes a golf ball having a dynamic friction coefficient of 0.52 or more.

Further, Patent Document 2 discloses a core, a cover provided outside the core and having dimples formed thereon, and a cover provided outside the cover having a contact angle of 90° or more and a dynamic contact angle of 85°. [0041] Patent Document 2 (claim 1, paragraphs 0041 and 0042) describes a golf ball including an outer surface layer formed of a material having a degree of

JP 2019-10190 A JP 2019-10191 A

Conventionally, it has been proposed to increase the water repellency of the surface of a golf ball, but such a golf ball tends to have a lower spin performance on approach shots. The present invention has been made in view of the above circumstances, and provides a golf ball that maintains spin performance on approach shots and improves flight distance on driver shots in rainy weather, etc., by controlling the composition of the coating film. intended to provide

The golf ball of the present invention, which has solved the above problems, has a golf ball body and at least one coating layer covering the golf ball body. It is formed from a paint containing an isocyanate compound and a silicone compound, the surface of the outermost layer coating has a water slide angle of less than 50°, and the surface of the outermost layer coating has a dynamic friction coefficient of 0.3 to characterized by being 0.9.

The outermost layer of the coating film is formed of a coating material containing a polyol compound, a polyisocyanate compound, and a silicone compound, and the outermost coating film has a predetermined water slide angle, thereby improving the water repellency of the outermost coating film. improves, and the flight distance of driver shots in rainy weather etc. is improved. In addition, since the outermost coating film has a predetermined coefficient of dynamic friction, spin performance on approach shots is also improved.

According to the present invention, it is possible to obtain a golf ball that is superior in flight distance on driver shots in rainy weather and in spin performance on approach shots.

1 is a partially cutaway cross-sectional view showing a golf ball according to one embodiment of the present invention; FIG.

The golf ball of the present invention has a golf ball body and at least one coating layer covering the golf ball body. The outermost layer of the coating film is formed of a paint containing a polyol compound, a polyisocyanate compound, and a silicone compound (hereinafter sometimes referred to as "outermost layer coating material"), and the outermost layer coating film The water sliding angle of the surface of is less than 50°, and the dynamic friction coefficient of the surface of the outermost layer coating film is 0.3 to 0.9. Since the outermost coating film has a predetermined water sliding angle, the water repellency of the outermost coating film is improved, making it difficult for water to adhere to the golf ball surface in rainy weather. Even if there is water on the surface, the water on the surface can be quickly blown off by hitting. Therefore, the flight distance of driver shots in rainy weather or the like is improved. In addition, since the outermost coating film has a predetermined coefficient of dynamic friction, spin performance on approach shots is also improved.

(Coating film)
The coating film may have a single layer structure or a multilayer structure. In the coating film, the outermost coating film positioned on the outermost layer of the golf ball is formed from the outermost coating material, and has a predetermined water sliding angle and dynamic friction coefficient. When the coating film has a single-layer structure, the single-layer coating film is formed from the outermost layer coating material and has a predetermined water sliding angle and dynamic friction coefficient. When the coating film has a multi-layer structure, at least the outermost coating film is formed from the outermost coating material and has a predetermined water slide angle and dynamic friction coefficient.

(Physical properties of the outermost coating film)
The water sliding angle of the surface of the outermost layer of the coating film is preferably 5° or more, more preferably 8° or more, still more preferably 10° or more, preferably less than 50°, more preferably 45° or less, and further It is preferably 40° or less. When the sliding angle is 5° or more, spin performance on approach shots is improved, and when the sliding angle is less than 50°, flight distance on driver shots in rainy weather or the like is further improved.

The coefficient of dynamic friction of the outermost layer of the coating film is preferably 0.3 or more, more preferably 0.35 or more, still more preferably 0.4 or more, and preferably 0.9 or less, more preferably 0.8 or less. , and more preferably 0.8 or less. If the coefficient of dynamic friction is 0.3 or more, the spin performance on approach shots will be further improved, and if it is 0.9 or less, the flight distance on driver shots will be further improved.

The water contact angle on the surface of the outermost coating film is preferably 75° or more, more preferably 80° or more. If the water contact angle is 75° or more, the flight distance performance on driver shots in rainy weather is excellent. Although the upper limit of the water contact angle is not particularly limited, it is preferably 120°. From the viewpoint of stability of flight performance, it is preferable that the outermost layer of the coating film of the golf ball does not include a surface with a water contact angle of less than 70°. That is, the outermost coating film of the golf ball preferably has a water contact angle of 70° or more at all positions.

The physical properties of the outermost layer coating film may be evaluated using a coating film formed on a baked plate. A method of forming a coating film on a baked plate will be described later. The water sliding angle of the coating film on the baked coated plate is preferably 2° or more, more preferably 4° or more, still more preferably 6° or more, preferably 50° or less, more preferably 45° or less, and still more preferably. is less than or equal to 40°. The water contact angle of the coating film on the baked coated plate is preferably 100° or more and preferably 120° or less. The water sliding angle of the baked coated plate before forming the coating film is more than 60°, and the water contact angle is 95°.

The thickness of the outermost layer of the coating film is preferably 2 µm or more, more preferably 4 µm or more, still more preferably 6 µm or more, and preferably 30 µm or less, more preferably 25 µm or less, and still more preferably 20 µm or less. When the thickness of the outermost layer of the coating film is 2 μm or more, spin performance on approach shots is further improved, and when it is 30 μm or less, an increase in spin amount on driver shots can be suppressed.

(Paint for outermost layer)
The outermost layer paint contains a polyol compound, a polyisocyanate compound and a silicone compound. Examples of the coating for the outermost layer include a so-called two-pack curable urethane coating that uses a polyol composition containing a polyol compound as a main component and a polyisocyanate composition containing a polyisocyanate compound as a curing agent. The silicone compound may be blended in either the polyol composition or the polyisocyanate composition.

(Polyol composition)
The polyol composition contains a polyol compound. Examples of the polyol compound include compounds having two or more hydroxy groups in the molecule. Examples of the polyol compound include a compound having a hydroxyl group at the terminal of the molecule and a compound having a hydroxyl group other than the terminal of the molecule. The polyol compounds may be used alone or in combination of two or more. The polyol compound contained in the polyol composition preferably does not have a polysiloxane structure. The carbinol-modified silicone oil described later is not included in the polyol compound.

Examples of the compound having a hydroxyl group at the end of the molecule include low-molecular-weight polyols having a molecular weight of less than 500 and high-molecular-weight polyols having a number-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, trimethylol; Examples include triols such as propane and hexanetriol. Examples of the high-molecular-weight polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, urethane polyols, and acrylic polyols. Examples of the polyether polyol include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), polyoxytetramethylene glycol (PTMG), and the like. Examples of the polyester polyol include polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexamethylene adipate (PHMA), and the like. Examples of the polycaprolactone polyol include poly-ε-caprolactone (PCL). Polyhexamethylene carbonate etc. are mentioned as said polycarbonate polyol.

The urethane polyol is a compound having a plurality of urethane bonds in the molecule and two or more hydroxy groups in one molecule. The urethane polyol is obtained, for example, by reacting the first polyol component and the first polyisocyanate component under conditions such that the hydroxyl groups of the first polyol component are excessive with respect to the isocyanate groups of the first polyisocyanate component. urethane prepolymers.

Examples of the first polyol component of the urethane polyol include polyether diol, polyester diol, polycaprolactone diol, polycarbonate diol, etc. Polyether diol is preferable. Examples of the polyether diol include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, etc. Among these, polyoxytetramethylene glycol is preferable.

The number average molecular weight of the polyether diol is preferably 500 or more, more preferably 600 or more, and preferably 4,000 or less, more preferably 3,500 or less, still more preferably 3,000 or less. If the number average molecular weight of the polyether diol is 500 or more, the distance between the cross-linking points in the coating film becomes long and the coating film becomes soft, thereby improving the spin performance. When the number average molecular weight is 4,000 or less, the distance between cross-linking points in the coating film does not become too long, and the stain resistance of the coating film becomes good. The number average molecular weight of the polyol component can be determined, for example, by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and an organic solvent-based GPC column (for example, "Shodex (registered (trademark) KF series”, etc.).

The first polyol component may contain a low molecular weight polyol having a molecular weight of less than 500. 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, trimethylol; Examples include triols such as propane and hexanetriol. The low-molecular-weight polyols may be used alone or in combination of two or more.

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

The first polyisocyanate component that can constitute the urethane polyol is not particularly limited as long as it has two or more isocyanate groups. Mixture of toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), _{paraphenylene} diisocyanate (PPDI); Alicyclic or aliphatic polyisocyanates such as diisocyanate (H ₆ XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate (NBDI). These polyisocyanates may be used alone or in combination of two or more.

The urethane polyol preferably has a polyether diol content of 30% by mass or more, more preferably 35% by mass or more, and still more preferably 40% by mass or more. Said polyether diol forms the soft segment in the coating. Therefore, when the content of the polyether diol is 30% by mass or more, the spin performance of the obtained golf ball is further improved.

The urethane polyol preferably has a weight average molecular weight of 5,000 or more, more preferably 5,300 or more, still more preferably 5,500 or more, and preferably 20,000 or less, more preferably 18,000 or less. More preferably, it is 16,000 or less. When the weight-average molecular weight of the urethane polyol is 5,000 or more, the distance between the cross-linking points in the coating film becomes long and the coating film becomes soft, thereby improving the spin performance. When the weight-average molecular weight is 20,000 or less, the distance between cross-linking points in the coating film does not become too long, and the stain resistance of the coating film is improved.

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, and preferably 200 mgKOH/g or less, more preferably 190 mgKOH/g or less, still more preferably. is 180 mgKOH/g or less. The hydroxyl value can be measured according to JIS K 1557-1, for example, by an acetylation method.

Examples of the compound having a hydroxy group other than at the end of the molecule include polyrotaxane having a hydroxy group, and a hydroxy group-modified vinyl chloride/vinyl acetate copolymer.

The polyrotaxane having a hydroxy group has a cyclic molecule having at least one hydroxy group, and a linear molecule that fits in the ring of the cyclic molecule and holds the cyclic molecule slidably and rotatably. In the polyrotaxane, the linear molecule has blocking groups at both ends thereof, thereby preventing elimination of the cyclic molecule. The above-mentioned polyrotaxanes do not include pseudorotaxanes in which cyclic molecules can be detached from linear molecules.

The polyrotaxane having a hydroxy group is composed of a cyclodextrin, a linear molecule inserted into the cyclic structure of the cyclodextrin, and a blockade that is placed at both ends of the linear molecule to prevent detachment of the cyclic molecule. It is preferred to have a group. Polyrotaxane has viscoelasticity because the cyclodextrin molecules that are skewered through the linear molecules can move along the linear molecules (pulley effect), and even if tension is applied, this pulley effect Since the tension can be uniformly dispersed by the , unlike conventional crosslinked polymers, it has an excellent property that cracks and scratches are extremely difficult to occur.

The cyclodextrin is a general term for oligosaccharides having a cyclic structure. Cyclodextrins are, for example, 6 to 8 D-glucopyranose residues cyclically linked by α-1,4-glucosidic bonds. Cyclodextrins include α-cyclodextrin (number of glucose: 6), β-cyclodextrin (number of glucose: 7), γ-cyclodextrin (number of glucose: 8), etc. α-cyclodextrin preferable. One of the cyclodextrins may be used alone, or two or more of them may be used in combination.

The linear molecule is not particularly limited as long as it is a linear molecule that holds the cyclic structure of cyclodextrin in a skewed manner so as to be slidable and rotatable. Examples of the linear molecule include polyalkylene, polyester, polyether, polyacryl, etc. Among these, polyether is preferable, and polyethylene glycol is particularly preferable. Polyethylene glycol has little steric hindrance, and can hold the cyclic structure of cyclodextrin in a skewed manner.

The weight average molecular weight of the linear molecule is preferably 5,000 or more, more preferably 6,000 or more, preferably 100,000 or less, and more preferably 80,000 or less.

The linear molecule preferably has functional groups at both ends. By having a functional group, it can be easily reacted with the blocking group. Examples of the functional group include a hydroxy group, a carboxy group, an amino group, and a thiol group.

The blocking groups are not particularly limited as long as they are arranged at both ends of the linear molecule and can prevent the cyclodextrin from leaving the linear molecule. Methods for preventing detachment include a method of physically preventing detachment using a bulky blocking group and a method of electrostatically preventing detachment using an ionic blocking group. The bulky capping group includes cyclodextrin, adamantyl group and the like. The number (retained amount) of cyclodextrin retained in the linear molecule is preferably 0.06 to 0.61, more preferably 0.11 to 0.48, more preferably 0.11 to 0.48, where the maximum retained amount is 1. 24 to 0.41 is more preferred. If it is less than 0.06, the pulley effect may not be exhibited, and if it exceeds 0.61, the cyclodextrin may be arranged too densely and the mobility of the cyclodextrin may be lowered.

As the polyrotaxane, at least part of the hydroxy groups of cyclodextrin are preferably modified with caprolactone chains. The caplactone modification relaxes the steric hindrance between the polyrotaxane and the polyisocyanate and increases the reaction efficiency with the polyisocyanate.

As the modification, for example, the hydroxy group of cyclodextrin is treated with propylene oxide to convert it to hydroxypropyl. Subsequently, ε-caprolactone is added to carry out ring-opening polymerization. As a result of this modification, a caprolactone chain —(CO(CH ₂ ) ₅ O)nH (n is a natural number from 1 to 100) forms an —O—C ₃ H ₆ —O— group outside the cyclic structure of the cyclodextrin. join through. n represents the degree of polymerization, and is preferably a natural number of 1-100, more preferably a natural number of 2-70, and even more preferably a natural number of 3-40. A hydroxy group is formed at the other end of the caprolactone chain by ring-opening polymerization. The terminal hydroxy groups of the caprolactone chain are capable of reacting with polyisocyanates.

The proportion of hydroxy groups modified with caprolactone chains is preferably 2 mol% or more, more preferably 5 mol% or more, and 10 mol% or more with respect to all hydroxy groups (100 mol%) possessed by cyclodextrin before modification. is more preferred. If the ratio of hydroxy groups modified with caprolactone chains is within the above range, the polyrotaxane becomes highly hydrophobic and highly reactive with polyisocyanate.

The hydroxyl value of the polyrotaxane is preferably 10 mgKOH/g or more, more preferably 15 mgKOH/g or more, still more preferably 20 mgKOH/g or more, and preferably 400 mgKOH/g or less, more preferably 300 mgKOH/g or less, and still more preferably 300 mgKOH/g or less. 220 mgKOH/g or less, particularly preferably 180 mgKOH/g or less. If the hydroxyl value of the polyrotaxane is within the above range, the reactivity with the polyisocyanate will be high, and the durability of the coating film will be good.

The weight-average molecular weight of the polyrotaxane as a whole is preferably 30,000 or more, more preferably 40,000 or more, still more preferably 50,000 or more, and preferably 3,000,000 or less, more preferably 2 , 500,000 or less, more preferably 2,000,000 or less. If the weight average molecular weight is 30,000 or more, the coating film will have sufficient strength, and if it is 3,000,000 or less, the coating film will have sufficient softness and the approach performance of the golf ball will be improved. . The weight average molecular weight of the polyrotaxane can be determined, for example, by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and an organic solvent-based GPC column (for example, "Shodex (registered trademark) manufactured by Showa Denko Co., Ltd. ) KF series”, etc.).

Specific examples of polyrotaxanes modified with polycaprolactone include Serm Superpolymer SH3400P, SH2400P, SH1310P, etc. manufactured by Advanced Soft Materials.

The hydroxy group-modified vinyl chloride/vinyl acetate copolymer can adjust the adhesiveness while maintaining the scratch resistance of the coating film. The hydroxy group-modified vinyl chloride/vinyl acetate copolymer can be obtained by, for example, a method of copolymerizing vinyl chloride, vinyl acetate, and a monomer having a hydroxy group (e.g., polyvinyl alcohol, hydroxyalkyl acrylate), or a method of copolymerizing vinyl chloride/vinyl acetate. It can be obtained by partially saponifying or completely saponifying a copolymer.

In the hydroxy group-modified vinyl chloride/vinyl acetate copolymer, the content of the vinyl chloride component is preferably 1% by mass or more, more preferably 20% by mass or more, still more preferably 50% by mass or more, and 99% by mass or less. Preferably, 95% by mass or less is more preferable. Specific examples of the hydroxy group-modified vinyl chloride/vinyl acetate copolymer include Solbin (registered trademark) A, Solbin AL, and Solbin TA3 manufactured by Nissin Chemical Industry Co., Ltd.

An embodiment (embodiment 1) of the polyol composition containing urethane polyol as a polyol compound; are placed at both ends of the cyclodextrin and have blocking groups that prevent the cyclodextrin from leaving, and at least part of the hydroxy groups of the cyclodextrin are via —O—C ₃ H ₆ —O— groups. Therefore, an embodiment (embodiment 2) containing a polyrotaxane modified with a caprolactone chain is preferred.

In the polyol composition of aspect 1, the content of the urethane polyol in the polyol compound contained in the polyol composition is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. is. It is also preferable that the polyol composition of the aspect 1 contains only the urethane polyol as the polyol compound.

In the polyol composition of aspect 2, the polyrotaxane content in the polyol compound contained in the polyol composition is preferably 10% by mass or more, more preferably 15% by mass or more, further preferably 20% by mass or more, and 100% by mass or more. % by mass or less is preferable, 90% by mass or less is more preferable, and 85% by mass or less is even more preferable.

The polyol composition of aspect 2 preferably contains polycaprolactone polyol as the polyol compound. The mass ratio of the polyrotaxane to the polycaprolactone polyol (polycaprolactone polyol/polyrotaxane) is preferably 0/100 or more, more preferably 5/95 or more, still more preferably 10/90 or more, and preferably 90/10 or less. , more preferably 85/15 or less, and still more preferably 80/20 or less.

The polyol composition of aspect 2 preferably contains the hydroxyl group-modified vinyl chloride/vinyl acetate copolymer as the polyol compound. The content of the hydroxyl group-modified vinyl chloride/vinyl acetate copolymer in the polyol compound contained in the polyol composition is preferably 4% by mass or more, more preferably 8% by mass or more, and preferably 50% by mass or less. % by mass or less is more preferable.

(Polyisocyanate composition)
Next, the polyisocyanate composition will be explained. The polyisocyanate composition contains a polyisocyanate compound. Examples of the polyisocyanate compound include compounds having two or more 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'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), paraphenylene diisocyanate (PPDI); 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate (H ₆ XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornene diisocyanate ( NBDI) and other alicyclic diisocyanates or aliphatic diisocyanates; and triisocyanates such as allohanate, biuret, isocyanurate and adduct of these diisocyanates. The said polyisocyanate may be used individually and may use 2 or more types together.

The allophanate compound is, for example, a triisocyanate obtained by further reacting a diisocyanate with a urethane bond formed by reacting a diisocyanate with a low-molecular-weight diol. The adduct is a triisocyanate obtained by reacting a diisocyanate with a low molecular weight triol such as trimethylolpropane or glycerin. The biuret compound is, for example, a triisocyanate having a biuret bond represented by the following formula (11). The isocyanurate form of diisocyanate is, for example, triisocyanate represented by the following formula (12).

式（１１）、（１２）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 (11) and (12), R represents a residue obtained by removing the isocyanate group from diisocyanate.

As the triisocyanate, an isocyanurate of hexamethylene diisocyanate, a biuret of hexamethylene diisocyanate, and an isocyanurate of isophorone diisocyanate are preferable.

In the present invention, the polyisocyanate composition preferably contains a triisocyanate compound. The content of the triisocyanate compound in the polyisocyanate contained in the polyisocyanate composition is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more. Most preferably, the polyisocyanate composition contains only a triisocyanate compound as the polyisocyanate compound.

The isocyanate group content (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. It is preferably 40% by mass or less, more preferably 35% by mass or less. The isocyanate group content (NCO %) of polyisocyanate can be expressed by 100×[moles of isocyanate groups in polyisocyanate×42 (molecular weight of NCO)]/total mass (g) of polyisocyanate.

Specific examples of the polyisocyanate include Barnok D-800, Barnok DN-950, Barnok DN-955 manufactured by DIC Corporation, Desmodur N75MPA/X manufactured by Sumika Bayer Urethane Co., Ltd., Desmodur N3300, Desmodur L75 (C), Sumidule E21-1, Nippon Polyurethane Industry Co., Ltd. CORONATE HX, CORONATE HK, Asahi Kasei Chemicals Co., Ltd. Duranate 24A-100, Duranate 21S-75E, Duranate TPA-100, Duranate TKA-100, Degussa VESTANAT T1890, etc. can be done.

The molar ratio (NCO group/OH group) of the hydroxy group (OH group) of the polyol composition and the isocyanate group (NCO group) of the polyisocyanate composition is preferably 0.1 or more, more preferably 0.2 or more. preferable. If the molar ratio (NCO group/OH group) is less than 0.1, the curing reaction will be insufficient. On the other hand, if the molar ratio (NCO group/OH group) is too large, the amount of isocyanate groups becomes excessive, and the resulting coating film becomes hard and brittle, and also has a poor appearance. Therefore, the molar ratio (NCO group/OH group) is preferably 1.5 or less, more preferably 1.4 or less, and even more preferably 1.3 or less. The reason why the appearance of the coating film obtained when the amount of isocyanate groups in the paint is excessive is that when the amount of isocyanate groups is excessive, the reaction between the moisture in the air and the isocyanate groups increases, resulting in a large amount of carbon dioxide gas. This is thought to occur because

When the polyol composition of aspect 1 is used as the polyol composition, the polyisocyanurate composition includes, as polyisocyanate compounds, biuret-modified hexamethylene diisocyanate, isocyanurate-modified hexamethylene diisocyanate and isophorone diisocyanurate. It preferably contains a modified isocyanurate. When a biuret-modified hexamethylene diisocyanate and an isocyanurate-modified are used in combination, the mixing ratio (biuret-modified/isocyanurate-modified) is preferably 20/40 to 40/20 in mass ratio, and 25/ 35 to 35/25 is more preferred.

When the polyol composition of aspect 2 is used as the polyol composition, the polyisocyanurate composition preferably contains an isocyanurate modified product and/or a biuret modified product of hexamethylene diisocyanate as the polyisocyanate compound.

(silicone compound)
The outermost layer coating material contains, in addition to the polyol compound and the polyisocyanate compound, a silicone compound different from the polyol compound. A silicone compound is a component that imparts water repellency to a coating film. Examples of the silicone compound include silicone resins, silicone oils, cured products of curable silicone resins, and reaction products of reactive silicone oils. The said silicone compound may be used individually and may use 2 or more types together. A silicone resin is a resin composed of siloxane bonds (Si—O—Si), and is a silicone having a three-dimensional structure in its molecule. Silicone oil is silicone with a linear structure.

(Carbinol-modified silicone oil)
As the silicone compound, carbinol-modified silicone oil is preferable. The carbinol-modified silicone oil may be used alone or in combination of two or more. The carbinol-modified silicone oil is a silicone oil into which at least one carbinol group has been introduced. In the carbinol-modified silicone oil, the carbinol group may be introduced at the end of the molecular chain or as a side chain of the molecular chain. The carbinol-modified silicone oil preferably has a carbinol group at one end of the molecular chain or at both ends of the molecular chain.

The carbinol-modified silicone oil is preferably represented by the following general formula (1).

（式（１）中、Ｒ¹は、置換または非置換の１価の炭化水素基を示す。Ｒ²は、アルキレン基を示す。Ｒ³は、アルキレン基を示す。ｘは０～３の整数を示す。ｙは０～２の整数を示す。ｚは０～６００の整数を示す。複数存在するＲ¹～Ｒ³は、それぞれ同一でも異なっていてもよい。）

(In formula (1), R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group. R ² represents an alkylene group. R ³ represents an alkylene group. x is an integer of 0 to 3. y represents an integer of 0 to 2. z represents an integer of 0 to 600. Plural R ¹ to R ³ may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ¹ include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. A plurality of R ¹ may be different from each other or all may be the same.

An alkyl group is mentioned as said aliphatic hydrocarbon group. The number of carbon atoms in the alkyl group is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. The alkyl group may be linear, branched, or cyclic. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and hexadecyl group. , heptadecyl group, octadecyl group, and other linear alkyl groups; isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, sec-pentyl group, neopentyl group, isooctyl group, 2-ethylhexyl group, isodecyl branched alkyl groups such as groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

The aromatic hydrocarbon group includes an aryl group, an alkylaryl group, and an aralkyl group. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 or more, preferably 18 or less, and more preferably 8 or less. A phenyl group etc. are mentioned as said aryl group. Examples of the alkylaryl group include a tolyl group and a xylyl group. Examples of the aralkyl group include benzyl group, 1-phenylethyl group, 2-phenylethyl group and methylbenzyl group.

Examples of the substituted monovalent hydrocarbon group include those in which at least one hydrogen atom of the unsubstituted monovalent hydrocarbon group is substituted with a substituent. Examples of the substituent include halogen atoms (fluorine, chlorine, bromine, iodine, etc.). Examples of the substituted monovalent hydrocarbon group include halogenated alkyl groups such as 3,3,3-trifluoropropyl group.

R ¹ is preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms or an aromatic hydrocarbon group having 6 to 8 carbon atoms. A hydrogen atom, a methyl group, and a phenyl group are particularly preferred.

The number of carbon atoms in the alkylene group represented by R ² or R ³ is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. Examples of the alkylene group include methylene group, ethylene group, trimethylene group, tetramethylene group, and pentamethylene group.

As for said x, 2 or 3 is preferable. As for said y, 2 is preferable. The z is preferably 0 or more, more preferably 1 or more, still more preferably 5 or more, and preferably 600 or less, more preferably 400 or less, still more preferably 250 or less.

More preferably, the carbinol-modified silicone oil is represented by the following general formula (2).

（式（２）中、Ｒ⁴は、置換または非置換の１価の炭化水素基を示す。Ｒ⁵は、アルキレン基を示す。ｍは０～２の整数を示す。ｎは０～６００の整数を示す。複数存在するＲ⁴およびＲ⁵は、それぞれ同一でも異なっていてもよい。）

(In formula (2), R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group. R ⁵ represents an alkylene group. m represents an integer of 0 to 2. n represents a represents an integer, and multiple R ⁴ and R ⁵ may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ⁴ include the same groups as those represented by R ¹ in the general formula (1). A plurality of R ⁴ may be different from each other or all may be the same. R ⁴ is preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms or an aromatic hydrocarbon group having 6 to 8 carbon atoms. A hydrogen atom, a methyl group, and a phenyl group are particularly preferred.

The number of carbon atoms in the alkylene group represented by R ⁵ is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. Examples of the alkylene group include methylene group, ethylene group, trimethylene group, tetramethylene group, and pentamethylene group.

As for said m, 2 is preferable. The n is preferably 0 or more, more preferably 1 or more, still more preferably 5 or more, and preferably 600 or less, more preferably 400 or less, still more preferably 250 or less.

The kinematic viscosity (25° C.) of the carbinol-modified silicone oil is preferably 1 mm ² /s or more, more preferably 5 mm ² /s or more, still more preferably 10 mm ² /s or more, and preferably 200 mm ² /s or less. , more preferably 100 mm ² /s or less, still more preferably 50 mm ² /s or less. The kinematic viscosity of the silicone oil is measured by a viscosity measurement method using a capillary viscometer according to JIS Z 8803 (2011).

The hydroxyl value of the carbinol-modified silicone oil is preferably 1 mgKOH/g or more, more preferably 5 mgKOH/g or more, still more preferably 10 mgKOH/g or more, and preferably 200 mgKOH/g or less, more preferably 150 mgKOH/g or less. , and more preferably 130 mgKOH/g or less.

The carbinol-modified silicone oil is commercially available, for example, X-22-4039, X-22-4015, KF-6000, KF-6001, KF-6002, KF-6003, X-22- 170BX, X-22-170DX (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The content of the carbinol-modified silicone oil in the outermost layer paint is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass, based on a total of 100 parts by mass of the polyol compound and the polyisocyanate compound. Above, more preferably 0.1 parts by mass or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 8 parts by mass or less. If the content is within the above range, the flight distance on driver shots in rainy weather or the like is further improved.

(Curable silicone resin)
The outermost layer coating material may contain a curable silicone resin as a silicone compound. The curable silicone resin has alkoxysilyl groups in its molecule, and cures at room temperature by cross-linking the alkoxysilyl groups in the presence of a curing catalyst, which will be described later. The silicone resin is silicone having a three-dimensional structure in its molecule.

Examples of the curable silicone resin include partial hydrolysis condensates of alkoxysilane compounds represented by general formula (3).

（式（３）中、Ｒ⁶は、水素原子、または、置換または非置換の１価の炭化水素基を示す。Ｒ⁷は、置換または非置換の１価の炭化水素基を示す。ａは、０～３の整数を示す。複数存在するＲ⁶およびＲ⁷は、それぞれ同一でも異なっていてもよい。）

(In formula (3), R ⁶ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group. R ⁷ represents a substituted or unsubstituted monovalent hydrocarbon group. a is , represents an integer of 0 to 3. Plural R ⁶ and R ⁷ may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ⁶ or R ⁷ include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. A plurality of R ⁶ and R ⁷ may be different from each other or all may be the same.

An alkyl group is mentioned as said aliphatic hydrocarbon group. The number of carbon atoms in the alkyl group is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. The alkyl group may be linear, branched, or cyclic. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and hexadecyl group. , heptadecyl group, octadecyl group, and other linear alkyl groups; isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, sec-pentyl group, neopentyl group, isooctyl group, 2-ethylhexyl group, isodecyl branched alkyl groups such as groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

The aromatic hydrocarbon group includes an aryl group, an alkylaryl group, and an aralkyl group. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 or more, preferably 18 or less, and more preferably 8 or less. A phenyl group etc. are mentioned as said aryl group. Examples of the alkylaryl group include a tolyl group and a xylyl group. Examples of the aralkyl group include benzyl group, 1-phenylethyl group, 2-phenylethyl group and methylbenzyl group.

Examples of the substituted monovalent hydrocarbon group include those in which at least one hydrogen atom of the unsubstituted monovalent hydrocarbon group is substituted with a substituent. Examples of the substituent include halogen atoms (fluorine, chlorine, bromine, iodine, etc.), hydroxy groups, cyano groups, amino groups, carboxy groups, and the like. Examples of the substituted monovalent hydrocarbon group include halogenated alkyl groups such as 3,3,3-trifluoropropyl group.

R ⁶ is preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms or an aromatic hydrocarbon group having 6 to 8 carbon atoms. A hydrogen atom, a methyl group, and a phenyl group are particularly preferred. The curable silicone resin preferably has only a methyl group or both a methyl group and a phenyl group as ^R6 .

R ⁷ is preferably an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms, and particularly preferably a methyl group or an ethyl group.

The a is an integer of 0 to 3, preferably 1 or 2.

Examples of the alkoxysilane compound represented by the general formula (1) include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, dimethyl Dimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, phenylmethyldimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane. The alkoxysilane compound represented by the general formula (1) may be used alone or in combination of two or more.

The partially hydrolyzed condensate of the alkoxysilane compound is obtained by adding water to the alkoxysilane compound and raising the temperature while stirring in the presence of a known catalyst to cause partial hydrolysis and condensation. It is obtained by

The kinematic viscosity (25° C.) of the curable silicone resin is preferably 0.1 mm ² /s or more, more preferably 0.5 mm ² /s or more, still more preferably 1.0 mm ² /s or more, and is 250 mm ^{2 .} /s or less, more preferably 150 mm ² /s or less, and even more preferably 100 mm ² /s or less. The kinematic viscosity of the curable silicone resin is measured by the viscosity measurement method using a capillary viscometer according to JIS Z 8803 (2011).

The content of the curable silicone resin in the outermost layer paint is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 100 parts by mass in total of the polyol compound and the polyisocyanate compound. It is 5 parts by mass or less.

(Curing catalyst)
The curing catalyst is not particularly limited as long as it can cure the curable silicone resin. Examples of the curing catalyst include organic tin compounds such as dibutyltin diacetate, dibutyltin dioctylate, and dibutyltin dilaurate; Aluminum compounds; organic zirconium compounds such as zirconium (acetylacetone), zirconium tris (acetylacetone), zirconium tetrakis (ethylene glycol monomethyl ether), zirconium tetrakis (ethylene glycol monoethyl ether), zirconium tetrakis (ethylene glycol monobutyl ether); titanium tetrakis ( ethylene glycol monomethyl ether), titanium tetrakis (ethylene glycol monoethyl ether), titanium tetrakis (ethylene glycol monobutyl ether) and other organic titanium compounds; hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and other mineral acids; formic acid, acetic acid, oxalic acid, organic acids such as trifluoroacetic acid; inorganic bases such as ammonia, sodium hydroxide and potassium hydroxide; organic bases such as ethylenediamine and alkanolamine; and amino compounds such as amino-modified silicone, aminosilane, silazane and amines. Among these, organic tin compounds, organic aluminum compounds, organic titanium compounds, and mineral acids are preferred.

The content of the curing catalyst in the outermost layer coating material is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and still more preferably 2 parts by mass with respect to 100 parts by mass of the curable silicone resin. 50 parts by mass or less is preferable, 20 parts by mass or less is more preferable, and 10 parts by mass or less is even more preferable.

(reactive silicone oil)
The outermost layer coating material may contain, as a silicone compound, a reactive silicone oil other than the carbinol-modified silicone. A reactive silicone oil is a silicone oil in which a reactive group is introduced into a part of silicon. The reactive silicone oil preferably has a reactive group at one end or both ends of the molecular chain. Examples of the reactive groups include hydrosilyl groups (SiH), silanol groups (SiOH), and alkoxysilyl groups (SiOR (R: alkyl group)).

The reactive silicone oil is preferably represented by general formula (4). In the reactive silicone oil, the silicon atom located at one end of the polysiloxane molecular chain constitutes the reactive group.

（式（４）中、Ｒ⁸は、置換または非置換の１価の炭化水素基を示す。Ｒ⁹は、水素原子、ヒドロキシ基、またはアルコキシ基を示す。ｂは０～２の整数を示す。ｃは０～６００の整数を示す。複数存在するＲ⁸およびＲ⁹は、それぞれ同一でも異なっていてもよい。）

(In formula (4), R ⁸ represents a substituted or unsubstituted monovalent hydrocarbon group; R ⁹ represents a hydrogen atom, a hydroxy group, or an alkoxy group; b represents an integer of 0 to 2; .c represents an integer of 0 to 600. Multiple R ⁸ and R ⁹ may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ⁸ include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. A plurality of R ⁸ may be different from each other or all may be the same.

An alkyl group is mentioned as said aliphatic hydrocarbon group. The number of carbon atoms in the alkyl group is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. The alkyl group may be linear, branched, or cyclic. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and hexadecyl group. , heptadecyl group, octadecyl group, and other linear alkyl groups; isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, sec-pentyl group, neopentyl group, isooctyl group, 2-ethylhexyl group, isodecyl branched alkyl groups such as groups; and cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

The aromatic hydrocarbon group includes an aryl group, an alkylaryl group, and an aralkyl group. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 or more, preferably 18 or less, and more preferably 8 or less. A phenyl group etc. are mentioned as said aryl group. Examples of the alkylaryl group include a tolyl group and a xylyl group. Examples of the aralkyl group include benzyl group, 1-phenylethyl group, 2-phenylethyl group and methylbenzyl group.

Examples of the substituted monovalent hydrocarbon group include those in which at least one hydrogen atom of the unsubstituted monovalent hydrocarbon group is substituted with a substituent. Examples of the substituent include halogen atoms (fluorine, chlorine, bromine, iodine, etc.). Examples of the substituted monovalent hydrocarbon group include halogenated alkyl groups such as 3,3,3-trifluoropropyl group.

R ⁸ is preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms or an aromatic hydrocarbon group having 6 to 8 carbon atoms. A hydrogen atom, a methyl group, and a phenyl group are particularly preferred.

^R9 represents a hydrogen atom, a hydroxy group, or an alkoxy group. The number of carbon atoms in the alkoxy group is preferably 1 or more, preferably 18 or less, and more preferably 8 or less. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group and a sec-butoxy group. Among these, R ⁹ is preferably an alkoxy group, more preferably a methoxy group or an ethoxy group.

2 is preferable for said b. The value of c is preferably 0 or more, more preferably 1 or more, still more preferably 5 or more, and is preferably 600 or less, more preferably 400 or less, and still more preferably 250 or less.

The dynamic viscosity (25° C.) of the reactive silicone oil is preferably 0.65 mm ² /s or more, more preferably 2 mm ² /s or more, still more preferably 5 mm ² /s or more, and 1000 mm ² /s or less. It is preferably 500 mm ² /s or less, more preferably 100 mm ² /s or less. The kinematic viscosity of the reactive silicone oil is measured by a viscosity measurement method using a capillary viscometer according to JIS Z 8803 (2011).

The content of the reactive silicone oil in the outermost layer paint is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and still more preferably 100 parts by mass in total of the polyol compound and the polyisocyanate compound. It is 5 parts by mass or less.

The content of the reactive silicone oil in the outermost layer coating material is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 50 parts by mass with respect to 100 parts by mass of the curable silicone resin. The amount is 200 parts by mass or less, preferably 150 parts by mass or less, and even more preferably 75 parts by mass or less.

The paint may be either a water-based paint using water as the main dispersion medium or a solvent-based paint using an organic solvent as the dispersion medium, but the solvent-based paint is preferred. For solvent-based coatings, preferred solvents include toluene, isopropyl alcohol, xylene, methyl ethyl ketone, methyl ethyl isobutyl ketone, ethylene glycol monomethyl ether, ethylbenzene, propylene glycol monomethyl ether, isobutyl alcohol, and ethyl acetate. Although the solvent may be blended in either the polyol composition or the polyisocyanate composition, it is preferably blended in each of the polyol composition and the polyisocyanate composition from the viewpoint of uniform curing reaction.

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

The paint further optionally contains ultraviolet absorbers, antioxidants, light stabilizers, fluorescent brighteners, antiblocking agents, leveling agents, slip agents, viscosity modifiers, and the like, which are generally used in golf ball paints. may contain additives that may be

When the coating film has a multi-layer structure, examples of the base resin constituting the coating film other than the outermost coating film include urethane resins, epoxy resins, acrylic resins, vinyl acetate resins, polyester resins, and the like. Urethane resin is preferred. Coating films other than the outer coating film may be formed from the same paint as the outermost coating film, or may be formed from other paints.

(Formation of coating film)
The coating film can be formed by applying a paint to the surface of the golf ball body. The method of applying the paint is not particularly limited, and known methods can be employed, such as spray coating and electrostatic coating.

In the case of spray coating using an air gun, the polyol composition and the polyisocyanate composition are supplied by respective pumps, continuously mixed by a line mixer placed immediately before the air gun, and the resulting mixture is sprayed. Alternatively, the polyol composition and the polyisocyanate composition may be separately spray-coated using an air spray system equipped with a mixing ratio control mechanism. The carbinol-modified silicone oil is preferably blended with the polyol composition or the polyisocyanate composition, and more preferably blended with the polyol composition. The coating may be applied by spraying once, or may be applied multiple times.

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

(golf ball body)
The golf ball of the present invention is not particularly limited as long as it has a golf ball body and at least one coating layer provided on the surface of the golf ball body. The structure of the golf ball body is not particularly limited, and may be a one-piece golf ball, a two-piece golf ball, a three-piece golf ball, a four-piece golf ball, a multi-piece golf ball with five or more pieces, or a thread-wound golf ball. . In either case, the present invention can be suitably applied.

(core)
The one-piece golf ball body and cores used in wound golf balls, two-piece golf balls and multi-piece golf balls will now be described.

For the one-piece golf ball body and core, a known rubber composition (hereinafter sometimes simply referred to as "core rubber composition") can be used. A rubber composition containing can be molded by hot pressing.

As the base rubber, it is particularly preferable to use high-cis polybutadiene containing 40% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more of cis-bonds that are advantageous for rebound. 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. The metal of the metal salt is preferably zinc, magnesium, calcium, aluminum or sodium, more preferably zinc. The amount of the co-crosslinking agent used is preferably 20 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the base rubber. When using an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as the co-crosslinking agent, it is preferable to blend a metal compound (eg, magnesium oxide). Organic peroxides are preferably used as the cross-linking initiator. Specifically, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy) Examples include organic peroxides such as hexane and di-t-butyl peroxide, and among these, dicumyl peroxide is preferably used. The amount of the cross-linking initiator compounded 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, and more preferably 100 parts by mass of the base rubber. It is 2 parts by mass or less.

The core rubber composition may further contain an organic sulfur compound. Diphenyl disulfides (eg, diphenyl disulfide, bis(pentabromophenyl) disulfide), thiophenols, and thionaphthols (eg, 2-thionaphthol) can be preferably used as the organic sulfur compound. The amount of the organic sulfur compound compounded 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, and more preferably Preferably, it is 3.0 parts by mass or less. The core rubber composition may further contain a carboxylic acid and/or a salt thereof. As the carboxylic acid and/or its salt, a carboxylic acid having 1 to 30 carbon atoms and/or its salt is preferable. As the carboxylic acid, either an aliphatic carboxylic acid or an aromatic carboxylic acid (such as benzoic acid) can be used. The amount of the carboxylic acid and/or its salt is 1 part by mass or more and 40 parts by mass or less per 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 weight modifiers such as zinc oxide and barium sulfate, anti-aging agents, color powder, and the like as appropriate. can be compounded. The heat press molding conditions for the core rubber composition may be appropriately set according to the rubber composition. After heating for 10 minutes to 40 minutes, it is preferable to heat at 160° C. to 180° C. for 5 minutes to 15 minutes in two stages.

(cover)
The golf ball body preferably has a core and a cover covering the core. In this case, the slab hardness of the cover composition is preferably set as appropriate according to the desired performance of the golf ball. For example, in the case of a distance golf ball where flight distance is important, the slab hardness of the cover composition is preferably 50 or more, more preferably 55 or more, even more preferably 60 or more, and preferably 80 or less in terms of Shore D hardness. 70 or less is more preferable, and 68 or less is even more preferable. By adjusting the slab hardness of the cover composition to 50 or more, a golf ball with a high launch angle and a low spin rate is obtained on driver shots and long iron shots, and flight distance is improved. By setting the slab hardness of the cover composition to 80 or less, a golf ball with excellent durability can be obtained. In the case of a spin-type golf ball where controllability is important, the slab hardness of the cover composition is preferably less than 50, preferably 20 or more, more preferably 23 or more, and even more preferably 25 or more in Shore D hardness. . If the slab hardness of the cover composition is less than 50 in Shore D hardness, the spin rate on approach shots will be high, and a golf ball that will easily stop on the green will be obtained. Further, by setting the slab hardness to 20 or more, the scratch resistance is improved. In the case of a plurality of cover layers, the slab hardness of the cover composition constituting each layer may be the same or different as long as it is within the above range.

In the case of a distance-type golf ball where flight distance is important, the thickness of the cover is preferably 0.3 mm or more, more preferably 0.5 mm or more, still more preferably 0.7 mm or more, and preferably 2.5 mm or less. It is preferably 2.2 mm or less, more preferably 2.0 mm or less. When the thickness of the cover is 0.3 mm or more, the resilience of the golf ball can be maintained.

In the case of a spin type golf ball where controllability is important, the thickness of the cover is preferably 0.1 mm or more, more preferably 0.2 mm or more, still more preferably 0.3 mm or more, and preferably 2.0 mm or less. It is preferably 1.5 mm or less, more preferably 1.0 mm or less. When the thickness of the cover is 0.1 mm or more, the shot feel of the golf ball is improved, and when the thickness is 2.0 mm or less, the resilience of the golf ball can be maintained.

The resin component that constitutes the cover is not particularly limited. For example, a thermoplastic polyamide elastomer commercially available under the trade name "Hytrel (registered trademark)" (e.g., "Hytrel 3548", "Hytrel 4047") from DuPont Toray Co., Ltd. thermoplastic polyester elastomer, a thermoplastic polyurethane elastomer commercially available from BASF Japan Ltd. under the trade name "Elastollan (registered trademark) (e.g., "Elastollan XNY97A")", trade name from Mitsubishi Chemical Corporation A thermoplastic styrene elastomer marketed under the trade name of "Lavalon (registered trademark)" or a thermoplastic polyester elastomer marketed under the trade name of "Primalloy" can be mentioned. The cover materials may be used alone or in combination of two or more.

Among these, as the resin component constituting the cover, a polyurethane resin is preferable for a spin type golf ball where controllability is emphasized, and an ionomer resin is preferable for a distance type golf ball where flight distance is emphasized. When a polyurethane resin is used as the resin component constituting the cover, the content of the polyurethane resin in the resin component is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. . When an ionomer resin is used as the resin component constituting the cover, the content of the ionomer resin in the resin component is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. .

The polyurethane may be in the form of so-called thermoplastic polyurethane or thermosetting polyurethane. A thermoplastic polyurethane is a polyurethane that shows plasticity when heated, and generally means a polyurethane having a linear structure with a certain degree of high molecular weight. On the other hand, thermosetting polyurethane (two-component curing type polyurethane) is obtained by reacting a low-molecular-weight urethane prepolymer with a curing agent (chain extender) to increase the molecular weight when molding the cover. Polyurethane. Thermosetting polyurethanes include polyurethanes with a straight chain structure and polyurethanes with a three-dimensional crosslinked structure by controlling the number of functional groups in the prepolymer and curing agent (chain extender) used. A thermoplastic elastomer is preferable as the polyurethane.

In addition to the resin components described above, the cover includes pigment components such as white pigments (e.g., titanium oxide), blue pigments, and red pigments, specific gravity modifiers such as calcium carbonate and barium sulfate, dispersants, anti-aging agents, and ultraviolet absorbers. Agents, light stabilizers, fluorescent materials, fluorescent brighteners, and the like may be contained within limits that do not impair the performance of the cover.

The manner in which the cover composition is used to mold the cover is not particularly limited, but the manner in which the cover composition is directly injection molded onto the core, or the manner in which a hollow shell is molded from the cover composition and the core is is covered with a plurality of shells and compression molded (preferably, a method of molding a hollow shell-like half shell from the cover composition, covering the core with two half shells, and compression molding). can be done. The golf ball body with the molded cover is preferably removed from the mold and, if necessary, subjected to surface treatments such as deburring, cleaning, and sandblasting. Also, if desired, marks can be formed.

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, it is difficult to obtain the dimple effect. Moreover, if the total number of dimples exceeds 500, the size of each dimple becomes small, and it is difficult to obtain the effect of the dimples. The shape of the dimples to be formed (plan view shape) is not particularly limited, and circular; may be used, or two or more may be used in combination.

When the golf ball is a multi-piece golf ball such as a three-piece golf ball, a four-piece golf ball, a five-piece golf ball, or a multi-piece golf ball, the intermediate layer provided between the core and the outermost cover layer may be, for example, a polyurethane resin or an ionomer resin. thermoplastic resins such as , polyamide resins and polyethylene; thermoplastic elastomers such as styrene elastomers, polyolefin elastomers, polyurethane elastomers and polyester elastomers; cured products of rubber compositions; Here, the ionomer resin includes, for example, a copolymer of ethylene and an α,β-unsaturated carboxylic acid in which at least part of the carboxyl groups in the copolymer is neutralized with metal ions, or a copolymer of ethylene and an α,β-unsaturated carboxylic acid. At least part of the carboxyl groups in the terpolymer of saturated carboxylic acid and α,β-unsaturated carboxylic acid ester is neutralized with metal ions. The intermediate layer may further contain a specific gravity adjuster such as barium sulfate or tungsten, an antioxidant, a pigment, or the like. The intermediate layer may be called an inner cover layer or an outer core layer depending on the configuration of the golf ball.

The golf ball preferably has a diameter of 40 mm to 45 mm. From the viewpoint of meeting the R&A (Royal and Ancient Golf Club of St Andrews) standard, the diameter is preferably 42.67 mm or more. From the viewpoint of air resistance, the diameter is preferably 44 mm or less, more preferably 42.80 mm or less. 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, more preferably 45.00 g or more. From the viewpoint that the R&A standard is satisfied, the mass is preferably 45.93 g or less.

When the golf ball has a diameter of 40 mm to 45 mm, the amount of compressive deformation (the amount of shrinkage in the compression direction) when the initial load of 98 N is applied and the final load of 1275 N is applied is preferably 2.0 mm or more. It is more preferably 2.2 mm or more, preferably 5.0 mm or less, and more preferably 4.5 mm or less. A golf ball having a compressive deformation amount of 2.0 mm or more does not become too hard and provides a good feel at impact. On the other hand, by setting the amount of compressive deformation to 5.0 mm or less, the resilience increases.

FIG. 1 is a partially cutaway cross-sectional view showing a golf ball 1 according to one embodiment of the present invention. A golf ball 1 has a spherical core 2 , an intermediate layer 3 covering the spherical core 2 , a cover 4 covering the intermediate layer 3 , and a coating 5 provided on the surface of the cover 4 . A large number of dimples 41 are formed on the surface of the cover 4 . The portion of the surface of the cover 4 other than the dimples 41 is a land 42 . The coating film 5 is formed from a coating containing a polyisocyanate composition, a polyol composition, and a silicone compound.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples, and any modifications and embodiments that do not depart from the scope of the present invention can be made within the scope of the present invention. Included in scope.

[Evaluation method]
(1) Core hardness (Shore C hardness)
The hardness measured at the surface portion of the core was defined as the core surface hardness. Also, the core was cut into a hemispherical shape, and the hardness measured at the center of the cut surface was defined as the core center hardness. The hardness was measured using an automatic hardness tester (manufactured by H. Burleith, Digitest II). The detector used was "Shore C".

(2) Slab hardness (Shore D hardness)
A sheet having a thickness of about 2 mm was prepared by injection molding using the intermediate layer composition and the cover composition, and stored at 23° C. for 2 weeks. The hardness was measured using an automatic hardness tester (manufactured by H. Burleith, Digitest II) in a state in which three or more of these sheets were stacked so as not to be affected by the measurement substrate. The detector used was "Shore D".

(3) Amount of compression deformation (mm)
The amount of deformation in the direction of compression (the amount of shrinkage of the core in the direction of compression) from when the core was loaded with an initial load of 98 N to when a final load of 1275 N was applied was measured.

(4) Baked coated plate The material of the test piece for forming the coating film was steel plate SPCC specified in JIS G 4314, and the shape was 0.8 mm thick, 70 mm wide, and 150 mm long. A primer surfacer was spray-coated on both sides of this test piece and dried. Subsequently, the surface was polished with water-resistant abrasive paper (No. P400) until the surface became smooth, washed with detergent and water, and dried. Next, an acrylic melamine-based resin enamel was spray-coated, allowed to stand at room temperature for 20 minutes, and then forcedly dried at 160° C. for 20 minutes to prepare a baked coated plate.
A coating film was formed on the resulting baked-on coated plate under the same conditions as in golf ball production, and the water slide angle of the coating film surface was measured.

(5) Film Thickness of Coating Film The surface of the golf ball was cut with a slicer and measured with a microscope.

(6) Water sliding angle The water sliding angle was measured using a sliding contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., DMo-501SA). The measurement conditions were as follows. In golf ball measurements, water was dropped onto the center of the dimple with the largest diameter.
Measurement method: sliding method Analysis method: perfect circle fitting method (section 60 dots)
Field of view: WIDE1
Aqueous liquid volume: 19 ± 1 µL (needle used: stainless steel needle 15G)
Sliding conditions: 0 to 90° (2.0° continuous tilt per second)
Sliding and movement judgment distance: Tilt angle when moving 3 dots or more

(7) Water contact angle The water contact angle was measured using a contact angle meter (Kyowa Interface Science Co., Ltd., DropMaster DM501, analysis software (FAMAS)). Syringe set 22G manufactured by Kyowa Interface Science Co., Ltd. was used as a glass syringe for droplets.
In the measurement, first, the software was started and the syringe was set on the contact angle meter. Subsequently, the measurement sample was set on the sample table so that the portion of the monitor on which water was dropped was horizontal. Then, 2 μL of water was dropped from the syringe, and the contact angle was measured 30 seconds after dropping. The contact angle was measured using the θ/2 method. In golf ball measurements, water was dropped onto the center of the dimple with the largest diameter.

(8) Dynamic Friction Coefficient The dynamic friction coefficient of golf balls was measured under the following conditions. Under the following conditions, the dynamic friction coefficient of the outermost coating film can be measured because the load is small and the moving speed is slow.
・Testing machine: Tribomaster TL201TS (manufactured by Trivolity)
・Measurement sample: golf ball face plate: stainless steel (manufactured by Nisshin Steel Co., Ltd., HT1770 (dimensions: 50 mm × 150 mm × thickness 2 mm)), arithmetic mean surface roughness Ra: 2.9 μm, maximum height Average value Ry: 21.7 μm was used.
- Manufacturing method of face plate: Obtained by air blasting the above stainless steel. As an abrasive, a 1:1 mixture of alumina powder (#60) and STEEL BALL (manufactured by Ervin Industries, ES300) was used. pressure of 4 to 6 kg/cm ² .
・Method for measuring Ra and Ry: Measured according to JIS B 0601-1994 using a surface roughness measuring machine (SJ-301, manufactured by Mitutoyo). Ra and Ry are average values of 6 measurement points. Also, the cutoff value λc was 2.5 mm.
・Temperature: 23°C
・Ball moving speed: 2mm/s
・Load: 1.96 N (200 gf)
- Measurement method: A ball was fixed with a chuck and moved on a flat plate at a constant speed while a load of 200 gf was applied to measure the dynamic friction force.
・Measurement item: dynamic friction (average value of 2-10mm section)

(9) Driver shot A driver (trade name “SRIXON Z765” manufactured by Sumitomo Rubber Industries, Ltd., shaft hardness: X, loft angle: 8.5°) was attached to a golf laboratory swing machine. A golf ball was hit at a head speed of 50 m/sec, and the spin rate and carry were measured. Carry is the distance from the point of launch to the point of impact, and the spin rate (rpm) was measured by taking a series of photographs of a hit golf ball. An average value was obtained from 10 measurements. The club face and ball were wetted and measurements were taken in the rain.

(10) Long Iron Shot A 5-iron (trade name “SRIXON Z765” manufactured by Sumitomo Rubber Industries, Ltd., shaft hardness: S, loft angle: 25°) was attached to a golf laboratory swing machine. A golf ball was hit at a head speed of 41 m/sec to measure the spin rate and carry. Carry is the distance from the point of launch to the point of impact, and the spin rate (rpm) was measured by taking a series of photographs of a hit golf ball. An average value was obtained from 10 measurements. The club face and ball were wetted and measurements were taken in the rain.

(11) Approach shot A sand wedge (RTX-3 BLD, loft angle 58°, manufactured by Cleveland Golf) was attached to a golf laboratory swing robot, and a golf ball was hit at a head speed of 16 m/s. Spin rate (rpm) was measured by taking a series of photographs of the golf ball. The measurement was performed 10 times for each golf ball, and the average value was taken as the spin rate. The club face and ball were wetted and measurements were taken in the rain.

[Manufacturing of Golf Ball Body]
1. Preparation of Spherical Core A rubber composition having the formulation shown in Table 1 was kneaded and hot-pressed at 150° C. for 19 minutes in upper and lower molds having hemispherical cavities to obtain spherical cores with a diameter of 39.7 mm. The amount of barium sulfate was adjusted so that the ball mass was 45.6 g.

Polybutadiene rubber: "BR730 (high-cis polybutadiene)" manufactured by JSR Corporation
Zinc acrylate: "ZN-DA90S" manufactured by Nippon Distillery Co., Ltd.
Zinc oxide: "Ginrei R" manufactured by Toho Zinc Co., Ltd.
Barium sulfate: "Barium sulfate BD" manufactured by Sakai Chemical Co., Ltd.
Bis (pentabromophenyl) disulfide: manufactured by Kawaguchi Chemical Industry Co., Ltd. Dicumyl peroxide: manufactured by NOF Corporation, "Percumyl (registered trademark) D"
Benzoic acid: manufactured by Emerald Kalama Chemical

2. Preparation of Intermediate Layer Composition and Cover Composition The ingredients shown in Tables 2 and 3 were mixed using a twin-screw kneading extruder to obtain a pellet-like intermediate layer composition and cover composition. prepared. The extrusion conditions were screw diameter 45 mm, screw rotation speed 200 rpm, screw L/D=35, and the formulation was heated to 160-230° C. at the die position of the extruder.

ハイミラン（登録商標）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アイオノマー樹脂

Himilan (registered trademark) AM7329: manufactured by Mitsui-DuPont Polychemicals, zinc ion-neutralized ethylene-methacrylic acid copolymer ionomer resin Himilan 1555: manufactured by Mitsui-DuPont Polychemicals, sodium ion-neutralized ethylene-methacrylic acid copolymer polymer ionomer resin

エラストラン（登録商標）ＮＹ８０Ａ：ＢＡＳＦジャパン社製、熱可塑性ポリウレタンエラストマー

Elastollan (registered trademark) NY80A: BASF Japan Co., Ltd., thermoplastic polyurethane elastomer

3. Molding of Intermediate Layer The intermediate layer composition obtained above was directly injection molded onto the spherical core obtained as described above to form an intermediate layer (thickness: 1.0 mm) covering the spherical core. formed.

4. Preparation of Reinforcement Layer A composition for a reinforcement layer (manufactured by Shinto Toryo Co., Ltd., trade name "Porin (registered trademark) 750LE") was prepared using a two-component curing type epoxy resin as a base resin. The main agent contains 30 parts by mass of bisphenol A solid epoxy resin and 70 parts by mass of solvent. The curing agent contains 40 parts by weight of modified polyamidoamine, 5 parts by weight of titanium dioxide, and 55 parts by weight of solvent. The mass ratio of the main agent and the curing agent was set to 1/1. This reinforcing layer composition was applied to the surface of the intermediate layer with an air gun and held in an atmosphere of 23° C. for 12 hours to form a reinforcing layer. The thickness of the reinforcing layer was 7 μm.

5. Molding of Cover A pellet-like cover composition was put into each concave part of the lower mold of the half-shell molding die and pressurized to mold the half-shell. The sphere on which the reinforcing layer was formed was concentrically covered with two half shells. This sphere and half-shell were put into a final mold with many pimples on the cavity surface. A cover (thickness: 0.5 mm) was molded by compression molding to obtain a golf ball body. A large number of dimples having a shape inverted from the pimples were formed on the cover.

6. Preparation of coating film (1) Preparation of polyol composition As the first polyol component, polytetramethylene ether glycol (PTMG, number average molecular weight: 650) and trimethylolpropane (TMP) were dissolved in a solvent (toluene, methyl ethyl ketone). The molar ratio of PTMG and TMP (TMP:PTMG) was 1.87:1. Here, dibutyltin laurate was added as a catalyst so as to be 0.1% by mass with respect to the entire main agent. While this polyol solution was maintained at 80° C., isophorone diisocyanate (IPDI) as a first polyisocyanate component was added dropwise to the solution. The molar ratio (NCO/OH) between the OH groups of the first polyol component and the NCO groups of the first polyisocyanate component was set to 0.6. After dropping, stirring was continued until isocyanate disappeared, and then the mixture was cooled to room temperature to prepare a polyol composition containing urethane polyol (urethane polyol content: 30% by mass). The resulting urethane polyol had a PTMG content of 46.2% by mass, a hydroxyl value of 128.0 mgKOH/g, and a weight average molecular weight of 7,200.

(2) Preparation of polyisocyanate composition Burette-modified hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals, Duranate (registered trademark) 21S-75E (NCO content: 15.5%)) 30 parts by mass, isocyanate of hexamethylene diisocyanate Nurate modified product (manufactured by Asahi Kasei Chemicals, Duranate TKA-100 (NCO content: 21.7%)) 30 parts by mass, isocyanurate modified product of isophorone diisocyanate (manufactured by Degussa, VESTANAT (registered trademark) T1890 (NCO content : 12.0%)) 40 parts by mass were mixed to prepare a polyisocyanate composition.

(3) Preparation of paint The materials shown in Table 4 were blended to obtain paint composition No. 1. 1 to No. 6 was prepared. The compounding ratio of the polyol composition and the polyisocyanate composition is such that the molar ratio (NCO/OH) between the OH groups in the polyol composition and the NCO groups in the polyisocyanate composition is 1.2/1.0. adjusted to be

カルビノール変性シリコーンオイルＮｏ．１：信越化学社製、Ｘ－２２－４０３９（動粘度（２５℃）：９０ｍｍ²／ｓ、水酸基価：５８ｍｇＫＯＨ／ｇ、ポリシロキサン分子鎖の末端ではないケイ素原子にカルビノール基が導入されたシリコーンオイル）
カルビノール変性シリコーンオイルＮｏ．２：信越化学社製、ＫＦ－６０００（動粘度（２５℃）：３５ｍｍ²／ｓ、水酸基価：１２０ｍｇＫＯＨ／ｇ、式（１）で表されるカルビノール変性シリコーンオイル（Ｒ¹：置換または非置換の１価の炭化水素基、Ｒ²：アルキレン基、Ｒ³：アルキレン基、ｘ：２の整数、ｙ：２の整数、ｚ：０～６００））
カルビノール変性シリコーンオイルＮｏ．３：信越化学社製、Ｘ－２２－１７０ＢＸ（動粘度（２５℃）：４０ｍｍ²／ｓ、水酸基価：２０ｍｇＫＯＨ／ｇ、式（２）で表されるカルビノール変性シリコーンオイル（Ｒ⁴：置換または非置換の１価の炭化水素基、Ｒ⁵：アルキレン基、ｍ：２の整数、ｚ：０～６００））
カルボキシ変性シリコーンオイル：信越化学社製、Ｘ－２２－１６２Ｃ（動粘度（２５℃）：２２０ｍｍ²／ｓ、官能基当量：２３００ｇ／ｍｏｌ、ポリシロキサン分子鎖の両末端に位置するケイ素原子にカルボキシ基が導入されたシリコーンオイル）

Carbinol-modified silicone oil No. 1: Shin-Etsu Chemical Co., Ltd., X-22-4039 (kinematic viscosity (25° C.): 90 mm ² /s, hydroxyl value: 58 mgKOH/g, a carbinol group was introduced to a silicon atom that is not a terminal of the polysiloxane molecular chain silicone oil)
Carbinol-modified silicone oil No. 2: Shin-Etsu Chemical Co., Ltd., KF-6000 (kinematic viscosity (25° C.): 35 mm ² /s, hydroxyl value: 120 mgKOH/g, carbinol-modified silicone oil represented by formula (1) (R ¹ : substituted or non-substituted substituted monovalent hydrocarbon group, R ² : alkylene group, R ³ : alkylene group, x: integer of 2, y: integer of 2, z: 0 to 600))
Carbinol-modified silicone oil No. 3: Shin-Etsu Chemical Co., Ltd., X-22-170BX (kinematic viscosity (25° C.): 40 mm ² /s, hydroxyl value: 20 mgKOH/g, carbinol-modified silicone oil represented by formula (2) (R ⁴ : substituted or an unsubstituted monovalent hydrocarbon group, R ⁵ : an alkylene group, m: an integer of 2, z: 0 to 600))
Carboxy-modified silicone oil: Shin-Etsu Chemical Co., Ltd., X-22-162C (kinematic viscosity (25° C.): 220 mm ² /s, functional group equivalent: 2300 g/mol, silicon atoms located at both ends of the polysiloxane molecular chain have carboxyl group-introduced silicone oil)

7. Formation of Paint Film The surface of the golf ball body obtained above was sandblasted and marked, then the paint was applied with a spray gun, dried in an oven at 40° C. for 24 hours, and the diameter was 42.7 mm. , and a golf ball having a mass of 45.6 g was obtained. The coating was performed by placing the golf ball body on a rotating body equipped with prongs, rotating the rotating body at 300 rpm, and moving the golf ball body vertically while separating the air gun from the golf ball body by a spraying distance (7 cm). The interval between each overcoating was set to 1.0 second. The spraying conditions of the air gun are: two coats, spraying air pressure: 0.15 MPa, pressurized tank air pressure: 0.10 MPa, one coating time: 1 second, ambient temperature: 20 ° C. to 27 ° C., ambient humidity: Coating was performed under the condition of 65% or less. Table 5 shows the evaluation results of the obtained golf balls.

Golf ball no. 1 to 4, the outermost layer coating film is formed from a coating containing a polyol compound, a polyisocyanate compound, and a silicone compound, and the surface of the outermost layer coating film has a water slide angle of less than 50 °, The dynamic friction coefficient of the surface of the outermost layer coating film is 0.3 to 0.9. All of these golf balls travel long distances on driver shots in the rain and have high spin rates on approach shots in the rain.

Golf ball no. In No. 5, the outermost coating film is formed from a coating containing a polyol compound, a polyisocyanate compound, and a carboxy-modified silicone oil, and the surface of the outermost coating film has a water slide angle of more than 50°. Golf ball no. In No. 6, the outermost coating film is formed from a coating containing no silicone oil. All of these golf balls have a short flight distance on driver shots in the rain and a low spin rate on approach shots in the rain.

1: golf ball, 2: spherical core, 3: intermediate layer, 4: cover, 41: dimple, 42: land, 5: coating film

Claims (9)

comprising a golf ball body and at least one coating film covering the golf ball body;
The outermost coating film is formed from a coating containing a polyol compound, a polyisocyanate compound, and a silicone compound,
The content of the triisocyanate compound in the polyisocyanate compound is 50% by mass or more,
The silicone compound is a carbinol-modified silicone oil,
The content of the carbinol-modified silicone oil is 0.1 parts by mass to 20 parts by mass with respect to a total of 100 parts by mass of the polyol compound and the polyisocyanate compound,
The water sliding angle of the surface of the outermost layer coating film measured under the following conditions is less than 50°,
A golf ball, wherein the dynamic friction coefficient of the surface of the outermost coating film is 0.3 to 0.9.
<Measurement conditions for water sliding angle>
Measuring device: Sliding contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., DMo-501SA)
Measurement method: Sliding method Measurement point: Water is dropped at the center of the dimple with the largest diameter Analysis method: Perfect circle fitting method (section 60 dots)
Field of view: WIDE1
Aqueous liquid volume: 19 ± 1 µL (needle used: stainless steel needle 15G)
Sliding conditions: 0 to 90° (2.0° continuous tilt per second)
Sliding and movement judgment distance: Tilt angle when moving 3 dots or more 2. The golf ball according to claim 1, wherein the surface of the outermost coating film has a water contact angle of 75° or more, as measured under the following conditions.
<Conditions for measurement of water contact angle>
Measuring device: contact angle meter (manufactured by Kyowa Interface Science, DropMaster DM501, analysis software (FAMAS))
Measurement method: Drop 2 μL of water onto the center of the dimple with the largest diameter, and measure the contact angle 30 seconds after dropping using the θ/2 method. 3. The golf ball of claim 1, wherein the carbinol-modified silicone oil has a hydroxyl value of 1 mgKOH/g to 200 mgKOH/g. 4. The golf ball according to any one of claims 1 to 3, wherein the carbinol-modified silicone oil has a carbinol group at one end of its molecular chain or at both ends of its molecular chain. The golf ball according to any one of claims 1 to 4, wherein the carbinol-modified silicone oil is represented by the following general formula (1).

(In formula (1), R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group. R ² represents an alkylene group. R ³ represents an alkylene group. x is an integer of 0 to 3. y represents an integer of 0 to 2. z represents an integer of 0 to 600. Plural R ¹ to R ³ may be the same or different.) The golf ball according to any one of claims 1 to 5, wherein the carbinol-modified silicone oil is represented by the following general formula (2).

(In formula (2), R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group. R ⁵ represents an alkylene group. m represents an integer of 0 to 2. n represents a represents an integer, and multiple R ⁴ and R ⁵ may be the same or different.) The golf ball according to any one of claims 1 to 6, wherein the outermost coating film has a thickness of 2 µm to 30 µm. The golf ball according to any one of claims 1 to 7, wherein the polyol compound contains urethane polyol. The polyol compound contains a polyrotaxane having a cyclic molecule having at least one hydroxy group and a linear molecule that fits in the ring of the cyclic molecule and holds the cyclic molecule slidably and rotatably. A golf ball according to any one of claims 1-7.

Images