JP7339764B2 - 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 golf ball surface when the golf ball is used in rainy weather.

For example, Patent Document 1 describes a golf ball whose outer surface is made of a water-repellent substance with a contact angle of 90° or more (see Patent Document 1 (claim 1, paragraphs 0016 and 0024). ).

JP-A-6-114125

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 was able to solve the above problems, has a golf ball body and at least one coating layer covering the golf ball body, the outermost coating layer containing a silicone compound, The thickness of the outermost layer coating film is 5 nm to 500 nm, and the water slide angle of the surface of the outermost layer coating film is less than 50°.

The outermost coating film contains a silicone compound and satisfies the above physical properties, thereby improving the water repellency of the outermost coating film, improving flight distance on driver shots in rainy weather, etc., and approach shots. The spin performance of is also good.

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 film covering the golf ball body, the outermost coating film containing a silicone compound, and the thickness of the outermost coating film being 5 nm. 500 nm, and the water slide angle of the surface of the outermost layer coating film is less than 50°. The outermost coating film contains a silicone compound and satisfies the above water slide angle, thereby improving the water repellency of the outermost coating film and making it difficult for water to adhere to the golf ball surface in rainy weather. In addition, even when water is present on the surface of the golf ball, the surface water can be quickly blown off by hitting. Therefore, the flight distance of driver shots in rainy weather or the like is improved. In addition, when the outermost coating film satisfies the above thickness, the 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 contains a silicone compound and has a predetermined water sliding angle and thickness. When the coating film has a single-layer structure, this single-layer coating film contains a silicone compound and has a predetermined water sliding angle and thickness. When the coating film has a multilayer structure, at least the outermost coating film contains a silicone compound and has a predetermined water sliding angle and thickness.

(Physical properties of the outermost coating film)
The thickness of the outermost coating film is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, and preferably 500 nm or less, more preferably 400 nm or less, and still more preferably 300 nm or less. When the thickness of the outermost layer coating film is 5 nm or more, flight distance on driver shots in rainy weather is improved, and when it is 500 nm or less, spin performance on approach shots is improved.

The water sliding angle of the surface of the outermost layer 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 still more preferably. is less than or equal to 40°. If the water slide angle is 5° or more, the spin performance on approach shots will be good, and if it is less than 50°, the flight distance on driver shots will be improved in rainy weather and the like.

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 dynamic friction coefficient of the surface 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 0.85. 0.8 or less, 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 good, and if it is 0.9 or less, the flight distance on driver shots in rainy weather or the like will be improved.

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 outermost coating film contains a silicone compound. Examples of the silicone compound include silicone resins, silicone oils, cured products of curable silicone resins, and reaction products of reactive silicone oils. 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.

The content of the silicone compound in the outermost coating film is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. When the content of the silicone compound is 50% by mass or more, the flight distance of driver shots in rainy weather or the like is improved.

The outermost coating film preferably has a low thermoplastic resin content. Examples of the thermoplastic resin include thermoplastic polyurethane and thermoplastic polyester. The content of the thermoplastic resin in the outermost coating film is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. More preferably, the outermost coating film does not contain thermoplastic polyurethane.

(Paint for outermost layer)
The outermost layer coating film is preferably formed from a paint containing a curable silicone resin, a curing catalyst, and a reactive silicone oil (hereinafter sometimes referred to as "outermost layer paint"). Since the outermost coating film is formed from a coating containing a curable silicone resin, a curing catalyst, and a reactive silicone oil, the water repellency of the outermost coating film is improved, and the golf ball surface is protected even in rainy weather. In addition, even when water is present on the surface of the golf ball, the surface water can be quickly blown off by hitting. Therefore, the flight distance of driver shots in rainy weather or the like is improved. In addition, the inclusion of the above components in the outermost coating film improves the spin performance on approach shots.

(Curable silicone resin)
The outermost layer coating contains a curable silicone resin. The curable silicone resin is a component that constitutes the skeleton of the coating film. 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.

Examples of the curable silicone resin include partial hydrolysis condensates of alkoxysilane compounds represented by general formula (1).

（式（１）中、Ｒ¹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。Ｒ²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Ｒ¹およびＲ²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 hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group.R ² represents a substituted or unsubstituted monovalent hydrocarbon group. a is , represents an integer of 0 to 3. Plural R ¹ and R ² may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ¹ or R ² include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. A plurality of R ¹ and R ² 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 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 curable silicone resin preferably has only a methyl group or both a methyl group and a phenyl group as R ¹ .

R ² 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 molecular weight of the curable silicone resin is preferably 100 or more, more preferably 200 or more, still more preferably 300 or more, and preferably 3000 or less, more preferably 2000 or less, still more preferably 1000 or less.

The curable silicone resin is preferably represented by the average compositional formula (2).

（式（２）中、Ｒ¹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。Ｒ²は、置換または非置換の１価の炭化水素基を示す。ｂは、０．４０から１．７０の範囲内にある値を示す。ｃは、平均組成式（２）で表される硬化性シリコーンレジン中のＯＲ²基の比率が５質量％以上になる値を示す。複数存在するＲ¹およびＲ²は、それぞれ同一でも異なっていてもよい。）

(In formula (2), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group.R ² represents a substituted or unsubstituted monovalent hydrocarbon group. b is , indicates a value within the range of 0.40 to 1.70, and c indicates a value at which the ratio of OR ² groups in the curable silicone resin represented by the average composition formula (2) is 5% by mass or more. Plural R ¹ and R ² may be the same or different.)

The substituted or unsubstituted monovalent hydrocarbon group represented by R ¹ and R ² in formula (2) includes the substituted or unsubstituted 1 represented by R ¹ and R ² in the general formula (1). and the same as the valent hydrocarbon group. R ¹ in formula (2) is preferably a hydrogen atom or an unsubstituted monovalent hydrocarbon group, more preferably an aliphatic hydrocarbon group having 1 to 18 carbon atoms, It is an aromatic hydrocarbon group, particularly preferably a hydrogen atom, a methyl group, or a phenyl group. R ² in formula (2) 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. be.

The alkoxy group content of the curable silicone resin is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, and is preferably 55% by mass or less, more preferably 45% by mass or less. , more preferably 35% by mass or less.

The curable silicone resin represented by the average compositional formula (2) is commercially available. 40-2308, X-40-9238 and the like. These commercially available curable silicone resins may be used alone or in combination of two or more.

The content of the curable silicone resin in the outermost layer paint is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more, and preferably 75% by mass or less. , more preferably 50% by mass or less, and still more preferably 20% 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 curing catalyst is commercially available, and examples thereof include D-20, DX-9740 and DX-175 manufactured by Shin-Etsu Chemical Co., Ltd. These curing catalysts may be used alone or in combination of two or more.

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.

The curing catalyst may be contained in advance in the curable silicone resin. A curable silicone resin containing a curing catalyst in advance is available as a commercial product. (curing catalyst DX-175; containing 5% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.).

(reactive silicone oil)
The outermost layer coating material contains a reactive silicone oil. Reactive silicone oil is a component that imparts water repellency to the coating film. 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)).

(First reactive silicone oil)
The reactive silicone oil contains one represented by the general formula (3) (hereinafter sometimes referred to as "first reactive silicone oil"). In the first reactive silicone oil, a silicon atom positioned at one end of the polysiloxane molecular chain constitutes a reactive group.

（式（３）中、Ｒ³は、置換または非置換の１価の炭化水素基を示す。Ｒ⁴は、水素原子、ヒドロキシ基、またはアルコキシ基を示す。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Ｒ³およびＲ⁴は、それぞれ同一でも異なっていてもよい。）

(In formula (3), R ³ represents a substituted or unsubstituted monovalent hydrocarbon group. R ⁴ represents a hydrogen atom, a hydroxy group, or an alkoxy group. m represents an integer of 0 to 2. .n represents an integer of 0 to 600. Plural R ³ and R ⁴ may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ³ include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. A plurality of R ³ 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 ³ 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.

^R4 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 ⁴ is preferably an alkoxy group, more preferably a methoxy group or an ethoxy 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 first 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. The following is preferable, more preferably 500 mm ² /s or less, and still 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 functional group equivalent of the first reactive silicone oil is preferably 500 g/mol or more, more preferably 1000 g/mol or more, still more preferably 1500 g/mol or more, and preferably 3000 g/mol or less, more preferably 2500 g/mol. mol or less, more preferably 2000 g/mol or less.

The first reactive silicone oil is preferably represented by general formula (4).

（式（４）中、Ｒ³は、置換または非置換の１価の炭化水素基を示す。Ｒ⁵は、アルキル基を示す。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Ｒ³およびＲ⁵は、それぞれ同一でも異なっていてもよい。）

(In formula (4), R ³ represents a substituted or unsubstituted monovalent hydrocarbon group. R ⁵ represents an alkyl group. m represents an integer of 0 to 2. n represents a represents an integer, and multiple R ³ and R ⁵ may be the same or different.)

R ³ , m and n in formula (4) have the same meanings as in formula (3).

The number of carbon atoms in the alkyl group represented by R ⁵ in formula (4) 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. R ⁵ is preferably a methyl group or an ethyl group.

The first reactive silicone oil is commercially available, and examples thereof include X-24-9377 and X-24-9011 manufactured by Shin-Etsu Chemical Co., Ltd. Moreover, these first reactive silicone oils may be used alone, or two or more of them may be used in combination.

The content of the first reactive silicone oil in the outermost layer paint is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 20% by mass or less, more preferably It is 10% by mass or less, more preferably 5% by mass or less.

The content of the first reactive silicone oil in the outermost layer paint 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. It is at least 200 parts by mass, preferably 150 parts by mass or less, and even more preferably 75 parts by mass or less.

The content of the first reactive silicone oil in the reactive silicone oil is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. As the reactive silicone oil, only the first reactive silicone oil may be contained.

(Second reactive silicone oil)
It is also preferable that the reactive silicone oil contains one represented by the general formula (5) (hereinafter sometimes referred to as "second reactive silicone oil"). The second reactive silicone oil has at least one hydroxyl group at both ends of the polysiloxane molecular chain.

（式（５）において、Ｒ⁶は、置換または非置換の１価の炭化水素基を示す。ｘは、０、１または２を示す。ｙは、０、１または２を示す。ｚは、１以上６００以下の整数を示す。複数存在するＲ⁶は、同一でも異なっていてもよい。）

(In formula (5), R ⁶ represents a substituted or unsubstituted monovalent hydrocarbon group. x represents 0, 1 or 2. y represents 0, 1 or 2. z is represents an integer of 1 or more and 600 or less, and multiple R ^6s may be the same or different.)

Examples of the unsubstituted monovalent hydrocarbon group represented by R ⁶ include the same groups as those represented by R ³ in the general formula (3). A plurality of R ⁶ may be different from each other or all may be the same. 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.

As for said x, 2 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.

The kinematic viscosity (25° C.) of the second reactive silicone oil is preferably 0.65 mm ² /s or more, more preferably 10 mm ² /s or more, still more preferably 35 mm ² /s or more, and 1000 mm ² /s. The following is preferable, more preferably 700 mm ² /s or less, and still more preferably 100 mm ² /s or less.

The functional group equivalent of the second reactive silicone oil is preferably 500 g/mol or more, more preferably 1000 g/mol or more, still more preferably 1200 g/mol or more, and preferably 2500 g/mol or less, more preferably 2000 g/mol. mol or less, more preferably 1800 g/mol or less.

The second reactive silicone oil is commercially available, for example, BY16-817, BY16-873, PRX413 (manufactured by Dow Corning Toray Co., Ltd.), YF3800, XF3905, YF3057 (manufactured by Momentive Performance・Materials Co., Ltd.), WACKER CT 601 M, WACKER FINISH WS 62 M (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.), X-21-5841, KF-9701 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

The content of the second reactive silicone oil in the outermost layer paint is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and preferably 10% by mass or less, more preferably It is 5% by mass or less, more preferably 3% by mass or less.

The content of the second reactive silicone oil in the outermost layer coating material is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and still more preferably 10 parts by mass with respect to 100 parts by mass of the curable silicone resin. It is at least 70 parts by mass, preferably 50 parts by mass or less, and even more preferably 35 parts by mass or less.

When the reactive silicone oil contains the first reactive silicone oil and the second reactive silicone oil, the content of the first reactive silicone oil in the reactive silicone oil is preferably 35% by mass or more, and more It is preferably 55% by mass or more, preferably 95% by mass or less, more preferably 85% by mass or less, and the content of the first reactive silicone oil in the reactive silicone oil is preferably 5% by mass or more, It is more preferably 15% by mass or more, preferably 65% by mass or less, and more preferably 45% by mass or less.

(solvent)
The outermost layer coating material may contain a solvent. The solvent is not particularly limited as long as it can dissolve or disperse the curable silicone resin, curing catalyst and reactive silicone oil. Examples of the solvent include alcohol solvents such as methanol, ethanol, propanol, isopropanol and butanol; ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate, ethyl glycol acetate and amyl acetate; ethylene glycol dimethyl ether and ethylene glycol diethyl ether. , diethylene glycol dimethyl ether, diethylene glycol diethyl ether and other glycol ether solvents; methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetylacetone and other ketone solvents; mineral spirits and other petroleum solvents; hexane, heptane, octane, nonane, decane, undecane, Aliphatic hydrocarbon solvents such as dodecane; naphthenic solvents such as cyclopentane and cyclohexane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; silicones such as volatile silicones (eg, volatile dimethylpolysiloxane) system solvents and the like. These solvents may be used alone or in combination of two or more.

In the outermost layer coating, optional ingredients generally used as glossing agents or protective agents, such as viscosity modifiers, anti-aging agents, UV absorbers, general Colorants such as pigments or dyes and fluorescent pigments, additives such as fragrances, surfactants, and silicone powders can be appropriately blended as needed.

The coating material for the outermost layer can be prepared by mixing arbitrary components such as the curable silicone resin, curing catalyst, reactive silicone oil, and, if necessary, a solvent. In the outermost layer paint, the total content of the curable silicone resin and the reactive silicone oil in the solid content is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass. % by mass or more. The solid content is a component other than the solvent among the components contained in the outermost layer coating material.

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 outermost coating film may be formed from the same paint as the outermost coating film, or may be formed from other paints.

(Polyurethane paint)
Coating films other than the outermost coating film are preferably formed from a coating containing a polyol composition and a polyisocyanate composition. Examples of the paint include a so-called two-component curing type urethane paint containing a polyol as a main component and a polyisocyanate as a curing agent.

(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.

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 preferred. 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 70% by mass or more, more preferably 72% by mass or more, and still more preferably 75% by mass or more. Said polyether diol forms the soft segment in the coating. Therefore, when the content of the polyether diol is 70% 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 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. and 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.

As the polyol composition, an embodiment (embodiment 1) containing urethane polyol; A polyrotaxane having a blocking group that prevents the elimination of cyclodextrin, and at least a portion of the hydroxy groups of the cyclodextrin are modified with caprolactone chains via —O—C ₃ H ₆ —O— groups. An embodiment (embodiment 2) containing polyrotaxane 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 a polycaprolactone polyol. 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. 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.

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.

In the curing reaction in the curable coating composition, the molar ratio (NCO group/OH group) of the hydroxyl group (OH group) possessed by the main agent and the isocyanate group (NCO group) possessed by the curing agent is preferably 0.1 or more. 0.2 or more is 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 a biuret-modified hexamethylene diisocyanate, an isocyanurate-modified hexamethylene diisocyanate and an isocyanurate-modified isophorone diisocyanurate. It is preferable to contain. 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.

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.

The paint preferably further contains a modified silicone. By containing modified silicone as a leveling agent, unevenness of the coated surface can be reduced, and a smooth coated surface can be formed on the golf ball surface. Examples of the modified silicone include those in which an organic group is introduced into the side chain or end of the polysiloxane skeleton, a polysiloxane block copolymer obtained by copolymerizing a polysiloxane block with a polyether block and/or a polycaprolactone block, or the above A polysiloxane block copolymer having an organic group introduced into its side chain or end can be used. The polysiloxane skeleton or polysiloxane block is preferably linear, and examples thereof include dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane. Examples of the organic group include an amino group, an epoxy group, a mercapto group, and a carbinol group. In the present invention, a polydimethylsiloxane-polycaprolactone block copolymer is preferably used as the modified silicone oil, and a terminal carbinol-modified polydimethylsiloxane-polycaprolactone block copolymer is more preferably used. This is because it has excellent compatibility with caprolactone-modified polyrotaxane and polycaprolactone polyol. Specific examples of the modified silicone used in the present invention include DBL-C31, DBE-224 and DCE-7521 manufactured by Gelest.

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.

(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. 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 any 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 formed dimples (planar view shape) is not particularly limited. 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. The mass is preferably 45.93 g or less from the viewpoint of satisfying the R&A standard.

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 composed of an inner layer 5a and an outer layer 5b. The inner layer 5a is formed of a paint containing a polyisocyanate composition and a polyol composition. The outer layer 5b is made of a paint containing the curable silicone resin, a curing catalyst, and reactive silicone oil.

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. Formation of inner layer 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) Polyisocyanate composition Buret-modified hexamethylene diisocyanate (manufactured by Asahi Kasei Chemicals, Duranate (registered trademark) 21S-75E (NCO content: 15.5%)) 30 parts by mass, isocyanurate-modified hexamethylene diisocyanate Body (manufactured by Asahi Kasei Chemicals, Duranate TKA-100 (NCO content: 21.7%)) 30 parts by mass, isocyanurate modified 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 Inner Layer Coating The polyol composition and the polyisocyanate composition obtained above were blended to prepare an inner layer coating. 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

(4) Formation of Inner Layer Coating Film The surface of the golf ball body obtained above is sandblasted and marked, then the inner layer coating is applied with a spray gun and the coating is dried in an oven at 40°C for 24 hours. to form an inner layer coating film. The thickness of the inner layer coating film was set to 10 μm.

The inner layer coating film is applied by placing the golf ball body on a rotating body equipped with prongs, rotating the rotating body at 300 rpm, and moving it vertically with an air gun spraying a distance (7 cm) away from the golf ball body. I went while 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.

7. Formation of Outer Layer Coating Next, the materials shown in Table 4 were blended to prepare an outer layer coating. In addition, golf ball No. 6 did not form an exterior coating.

硬化性シリコーンレジンＮｏ．１：信越化学社製、ＫＲ－２１７（動粘度（２５℃）：８ｍｍ²／ｓ、アルコキシ基量：２５質量％、式（２）中のＲ¹：フェニル基、式（２）中のＲ²：炭素数１～８のアルキル基、式（２）中のｂ：０．４０～１．７０、分子量：１０００以下）
硬化性シリコーンレジンＮｏ．２：信越化学社製、ＫＲ－５００（動粘度（２５℃）：２５ｍｍ²／ｓ、アルコキシ基量：２８質量％、式（２）中のＲ¹：メチル基、式（２）中のＲ²：炭素数１～８のアルキル基、式（２）中のｂ：０．４０～１．７０、分子量：１０００以下）
硬化性シリコーンレジンＮｏ．３：信越化学社製、Ｘ－４０－２３０８（動粘度（２５℃）：４ｍｍ²／ｓ、アルコキシ基量：５１質量％、式（２）中のＲ²：炭素数１～８のアルキル基、式（２）中のｂ：０、分子量：１０００以下）
硬化性シリコーンレジンと硬化触媒との混合物Ｎｏ．１：信越化学社製、ＫＲ－４００（動粘度（２５℃）：１．２ｍｍ²／ｓ、アルコキシ基量：４５質量％、式（２）中のＲ¹：メチル基、式（２）中のＲ²：炭素数１～８のアルキル基、式（２）中のｂ：０．４０～１．７０、分子量：１０００以下）（硬化触媒ＤＸ－９７４０（有機アルミニウム化合物タイプ）１０質量％含有）
硬化性シリコーンレジンと硬化触媒との混合物Ｎｏ．２：信越化学社製、Ｘ－４０－１７５（動粘度（２５℃）：２２ｍｍ²／ｓ、アルコキシ基量：３３質量％、式（２）中のＲ¹：メチル基およびフェニル基、式（２）中のＲ²：炭素数１～８のアルキル基、式（２）中のｂ：０．４０～１．７０、分子量：１０００以下）（硬化触媒ＤＸ－１７５（有機チタニウム化合物タイプ）５質量％含有）
硬化触媒：信越化学社製、Ｄ－２０（有機チタニウム化合物タイプ）
反応性シリコーンオイルＮｏ．１：信越化学社製、Ｘ－２４－９３７７（動粘度（２５℃）：６ｍｍ²／ｓ、官能基当量：１５００～２０００ｇ／ｍｏｌ、式（４）で表される反応性シリコーンオイル（Ｒ³：炭素数１～８のアルキル基、Ｒ⁵：メチル基、ｎ：０～６００、ｍ：０～２））
反応性シリコーンオイルＮｏ．２：信越化学社製、Ｘ－２４－９０１１（動粘度（２５℃）：２０ｍｍ²／ｓ、官能基当量：１５００～２０００ｇ／ｍｏｌ、式（４）で表される反応性シリコーンオイル（Ｒ³：炭素数１～８のアルキル基、Ｒ⁴：メチル基、ｎ：０～６００、ｍ：０～２））

Curable Silicone Resin No. 1: Shin-Etsu Chemical Co., Ltd., KR-217 (kinematic viscosity (25° C.): 8 mm ² /s, alkoxy group content: 25% by mass, R ¹ in formula (2): phenyl group, R in formula (2) ² : alkyl group having 1 to 8 carbon atoms, b in formula (2): 0.40 to 1.70, molecular weight: 1000 or less)
Curable Silicone Resin No. 2: Shin-Etsu Chemical Co., Ltd., KR-500 (kinematic viscosity (25° C.): 25 mm ² /s, alkoxy group content: 28% by mass, R ¹ in formula (2): methyl group, R in formula (2) ² : alkyl group having 1 to 8 carbon atoms, b in formula (2): 0.40 to 1.70, molecular weight: 1000 or less)
Curable Silicone Resin No. 3: Shin-Etsu Chemical Co., Ltd., X-40-2308 (kinematic viscosity (25° C.): 4 mm ² /s, alkoxy group content: 51% by mass, R ² in formula (2): alkyl group having 1 to 8 carbon atoms , b in formula (2): 0, molecular weight: 1000 or less)
Mixture No. of curable silicone resin and curing catalyst. 1: Shin-Etsu Chemical Co., Ltd., KR-400 (kinematic viscosity (25° C.): 1.2 mm ² /s, alkoxy group content: 45% by mass, R ¹ in formula (2): methyl group, in formula (2) R ² : alkyl group having 1 to 8 carbon atoms, b in formula (2): 0.40 to 1.70, molecular weight: 1000 or less) (curing catalyst DX-9740 (organoaluminum compound type) containing 10 mass% )
Mixture No. of curable silicone resin and curing catalyst. 2: Shin-Etsu Chemical Co., Ltd., X-40-175 (kinematic viscosity (25° C.): 22 mm ² /s, alkoxy group content: 33% by mass, R ¹ in formula (2): methyl group and phenyl group, formula ( R ² in 2): alkyl group having 1 to 8 carbon atoms, b in formula (2): 0.40 to 1.70, molecular weight: 1000 or less) (curing catalyst DX-175 (organotitanium compound type) 5 mass % content)
Curing catalyst: Shin-Etsu Chemical Co., Ltd., D-20 (organic titanium compound type)
Reactive silicone oil no. 1: Shin-Etsu Chemical Co., Ltd., X-24-9377 (kinematic viscosity (25° C.): 6 mm ² /s, functional group equivalent: 1500 to 2000 g/mol, reactive silicone oil represented by formula (4) (R ³ : alkyl group having 1 to 8 carbon atoms, R ⁵ : methyl group, n: 0 to 600, m: 0 to 2))
Reactive silicone oil no. 2: Shin-Etsu Chemical Co., Ltd., X-24-9011 (kinematic viscosity (25° C.): 20 mm ² /s, functional group equivalent: 1500 to 2000 g/mol, reactive silicone oil represented by formula (4) (R ³ : alkyl group having 1 to 8 carbon atoms, R ⁴ : methyl group, n: 0 to 600, m: 0 to 2))

The surface of the golf ball with the inner layer coating film was spray-coated, dried at 60° C. for 30 minutes, and then wiped off with a micro cloth to form an outer coating layer to obtain a golf ball.
Table 5 shows the evaluation results of the obtained golf balls.

Golf ball no. In Nos. 1 to 4, the outermost layer of the coating film contains a silicone compound, the thickness of the outermost layer coating film is 5 nm to 500 nm, and the water sliding fall angle of the surface of the outermost layer coating film is less than 50°. All of these golf balls are excellent in flight distance on driver shots in rainy weather and spin performance on approach shots.

Golf ball no. In No. 5, the outermost layer of the coating film contains a silicone compound, the thickness of the outermost coating film is 5 nm to 500 nm, and the water slide angle of the surface of the outermost coating film is 50° or more. This golf ball No. 5 has a short flight distance on driver shots in the rain and a small spin rate on approach shots in the rain.

1: golf ball, 2: spherical core, 3: intermediate layer, 4: cover, 41: dimples, 42: land, 5: coating film, 5a: inner layer, 5b: outer layer

Claims (8)

comprising a golf ball body and at least one coating film covering the golf ball body;
The outermost coating film contains a silicone compound,
The content of the silicone compound in the outermost layer coating film is 90% by mass or more,
The thickness of the outermost coating film is 5 nm to 500 nm,
The dynamic friction coefficient of the surface of the outermost layer coating film is 0.56 to 0.9,
A golf ball, wherein the water slide angle of the surface of the outermost coating film is 5° or more and less than 50°, as measured under the following conditions.
<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 of claim 1, wherein the content of the thermoplastic resin in the outermost coating film is 10% by mass or less. 3. The golf ball according to claim 1, wherein the outermost coating film is formed from a coating containing a curable silicone resin, a curing catalyst, and a reactive silicone oil. 4. The golf ball of claim 3, wherein the curable silicone resin is a partially hydrolyzed condensate of an alkoxysilane compound represented by formula (1).

(In formula (1), R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group.R ² represents a substituted or unsubstituted monovalent hydrocarbon group. a is , represents an integer of 0 to 3. Plural R ¹ and R ² may be the same or different.) 5. The golf ball of claim 3, wherein the curable silicone resin has an alkoxy group content of 10% by mass to 55% by mass. The reactive silicone oil has a reactive group at one end of the molecular chain or at both ends of the molecular chain,
The golf ball according to any one of claims 3 to 5, wherein the reactive group is at least one selected from the group consisting of hydrosilyl groups, silanol groups and alkoxysilyl groups. The golf ball according to any one of claims 3 to 6, wherein the reactive silicone oil contains a first reactive silicone oil represented by the following general formula (3).

(In formula (3), R ³ represents a substituted or unsubstituted monovalent hydrocarbon group. R ⁴ represents a hydrogen atom, a hydroxy group or an alkoxy group. m represents an integer of 0-2. n represents an integer of 0 to 600. Multiple R ³ and R ⁴ may be the same or different.) 8. The golf ball of claim 7, wherein the content of the first reactive silicone oil in the paint is 200 parts by mass or less with respect to 100 parts by mass of the curable silicone resin.

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