JP2013078462A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having excellent distinguishability.SOLUTION: The golf ball 2 includes a spherical core 4, a cover 6 positioned outside the core 4, and a paint layer 8 positioned outside the cover 6. The core 4 includes a spherical center 10 and a mid layer 12 positioned outside the center 10. The cover 6 is formed from a resin composition that includes a base resin and a fluorescent pigment. The paint layer 8 is formed from a resin composition that includes a base resin and a light-collecting fluorescent dye. A product of an amount of the light-collecting fluorescent dye per 100 parts by weight of the base resin in the paint layer 8 and a thickness (mm) of the paint layer 8 is higher than 5.0×10and lower than 2.0×10. A type of color of the light-collecting fluorescent dye included in the paint layer 8 is the same as a type of color of the fluorescent pigment included in the cover 6. The paint layer 8 includes no white inorganic pigment.

Description

  The present invention relates to a golf ball. In particular, the present invention relates to colored golf balls.

  The golf ball includes a core and a cover. A general golf ball is colored white. Coloring is achieved by dispersing titanium dioxide in the cover. Titanium dioxide has a high hiding power. Titanium dioxide hides the color of the core. Coloring may be achieved by dispersing a white pigment in the paint layer.

  Because most golf balls are white, golfers may mistake others' balls as their own. A penalty is imposed on the golfer who hit another person's ball.

  A mark is printed on the golf ball. The mark includes a brand and a ball number. Golfers can distinguish their balls from others by brand. Golfers can also identify their own balls from others by the ball number. The golfer approaches the ball and identifies the ball based on the mark. From a distance, identification based on the mark is difficult.

  There are golf balls colored other than white. This golf ball is referred to as a “color ball”. Color balls can be easily distinguished from white balls.

  Japanese Patent Application Laid-Open No. 58-116370 discloses a golf ball in which a cover contains a colorant and a paint layer contains a colorant. The colorant of the cover and the colorant of the paint layer are similar colors. In this golf ball, even if a part of the paint layer is damaged and the cover is exposed, it is not noticeable.

  Japanese Patent Application Laid-Open No. 2007-160087 discloses a golf ball whose cover contains a condensing dye. This golf ball has excellent visibility when placed on the lawn.

JP 58-116370 A JP2007-160087

  The appearance of the golf ball disclosed in JP-A-58-116370 is inferior in transparency. The visibility of this golf ball is not sufficient. Even with the golf ball disclosed in Japanese Patent Application Laid-Open No. 2007-160087, there is room for improvement in visibility.

  The light-collecting fluorescent dye is inferior in compatibility with the base resin of the cover, such as an ionomer resin. The condensing fluorescent dye bleeds from the cover resin composition containing the condensing fluorescent dye. In the golf ball manufacturing process disclosed in Japanese Patent Application Laid-Open No. 2007-160087, facilities such as a mold, a screw of an extruder, a hose for transferring a resin composition, and the like are contaminated with a condensing fluorescent dye. The production of a golf ball disclosed in Japanese Patent Application Laid-Open No. 2007-160087 is not realistic.

  An object of the present invention is to provide a colored golf ball which is colored and has excellent discrimination and also has excellent visibility.

The golf ball according to the present invention includes a core, a cover that covers the core, and a paint layer that covers the cover. The paint layer is formed from a resin composition containing a base resin and a condensing fluorescent dye. The product of the amount of the condensing fluorescent dye with respect to 100 parts by mass of the base resin in the paint layer and the thickness (mm) of the paint layer is larger than 4.0 × 10 ^{−5 and} smaller than 6.0 × 10 ^−3. .

  Preferably, the paint layer is transparent. Preferably, the paint layer does not contain a white inorganic pigment.

  The cover can be molded from a resin composition containing a base resin and a fluorescent pigment. Preferably, this resin composition contains 0.01 to 5.0 parts by mass of a fluorescent pigment with respect to 100 parts by mass of the base resin.

  Preferably, the light-collecting fluorescent dye contained in the paint layer and the fluorescent pigment contained in the cover have the same color.

  Preferably, the resin composition of the cover includes 0.05 part by mass or more and 5.0 parts by mass or less of a white inorganic pigment with respect to 100 parts by mass of the base resin.

  The core may consist of a plurality of layers. Preferably, the outermost layer of the core is molded from a resin composition containing 100 parts by mass of a base resin and 1.0 part by mass or more and 10.0 parts by mass or less of a white inorganic pigment.

In the golf ball according to the present invention, since the paint layer contains a condensing fluorescent dye, the paint layer emits intense fluorescence. For golf balls in which the product of the amount of the condensing fluorescent dye and the thickness of the paint layer is greater than 4.0 × 10 ^{−5 and} less than 6.0 × 10 ⁻³ , not only the color of the paint layer but also the color of the cover Will affect the appearance. Due to the synergistic effect of the color of the cover and the color of the paint layer, this golf ball achieves excellent visibility.

FIG. 1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  The golf ball 2 shown in FIG. 1 includes a spherical core 4, a cover 6 located outside the core 4, and a paint layer 8 located outside the cover 6. The core 4 includes a spherical center 10 and an intermediate layer 12 located outside the center 10. The intermediate layer 12 is the outermost layer in the core 4. A large number of dimples 14 are formed on the surface of the cover 6. A portion other than the dimples 14 on the surface of the cover 6 is a land 16.

  The golf ball 2 preferably has a diameter of 40 mm to 45 mm. The diameter is particularly preferably equal to or greater than 42.67 mm from the viewpoint that US Golf Association (USGA) standards are satisfied. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm, and particularly preferably equal to or less than 42.80 mm. The golf ball 2 preferably has a mass of 40 g or more and 50 g or less. In light of attainment of great inertia, the mass is more preferably equal to or greater than 44 g, and particularly preferably equal to or greater than 45.00 g. In light of satisfying the USGA standard, the mass is particularly preferably equal to or less than 45.93 g.

  The center 10 is formed by crosslinking a rubber composition. Examples of the base rubber of this rubber composition include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, and natural rubber. Two or more kinds of rubbers may be used in combination. From the viewpoint of resilience performance, polybutadiene is preferred, and high cis polybutadiene is particularly preferred.

  For crosslinking of the center 10, a co-crosslinking agent is preferably used. From the viewpoint of resilience performance, preferred co-crosslinking agents are zinc acrylate, magnesium acrylate, zinc methacrylate and magnesium methacrylate. It is preferable that the rubber composition contains an organic peroxide together with a co-crosslinking agent. Preferred organic peroxides include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butyl). Peroxy) hexane and di-t-butyl peroxide.

  The rubber composition of the center 10 may include a colorant. When the mid layer 12, the cover 6, and the paint layer 8 are transparent, the color of the center 10 affects the color of the golf ball 2. Examples of the colorant include dyes and pigments. When the center 10 is colored white, the rubber composition may include titanium dioxide.

  In the rubber composition of the center 10, various additives such as a filler, sulfur, a vulcanization accelerator, a sulfur compound, an anti-aging agent, a plasticizer, and a dispersant are blended in appropriate amounts as necessary. Synthetic resin powder or crosslinked rubber powder may be blended with the rubber composition.

  The center 10 has a diameter of preferably 30.0 mm or more, particularly preferably 38.0 mm or more. The diameter of the center 10 is preferably 42.0 mm or less, and particularly preferably 41.5 mm or less. The center 10 may be composed of two or more layers. The center 10 may include a rib on the surface thereof. The center 10 may be hollow.

  The mid layer 12 is made of a resin composition. A polymer suitable for this resin composition is an ionomer resin. A preferable ionomer resin includes a binary copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. Other preferable ionomer resins include ternary α-olefin, α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α, β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. A copolymer is mentioned. In this binary copolymer and ternary copolymer, preferred α-olefins are ethylene and propylene, and preferred α, β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. In this binary copolymer and ternary copolymer, some of the carboxyl groups are neutralized with metal ions. Examples of the metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions, and neodymium ions.

  In the mid layer 12, an ionomer resin and another resin may be used in combination. A particularly preferred resin that can be used in combination is a styrene block-containing thermoplastic elastomer. The styrene block-containing thermoplastic elastomer includes a polystyrene block as a hard segment and a soft segment. The styrene block-containing thermoplastic elastomer includes styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS), SBS hydrogenated, SIS hydrogenated and SIBS hydrogenated are included. Examples of the hydrogenated product of SBS include styrene-ethylene-butylene-styrene block copolymer (SEBS). As a hydrogenated product of SIS, styrene-ethylene-propylene-styrene block copolymer (SEPS) can be mentioned. Examples of the hydrogenated product of SIBS include styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS). An alloy of olefin and one or more selected from the group consisting of SBS, SIS, SIBS, SEBS, SEPS, and SEEPS, and hydrogenated products thereof may be used for the resin composition of the intermediate layer 12. Good.

  Other resins may be used for the intermediate layer 12 instead of the ionomer resin. Examples of other resins include polystyrene, polyamide, polyester, polyolefin, and polyurethane. Two or more kinds of resins may be used in combination.

  The resin composition of the mid layer 12 can include a white inorganic pigment. The core 4 provided with the intermediate layer 12 containing a white inorganic pigment exhibits a white color. The lightness of the golf ball 2 provided with the core 4 is large. The core 4 contributes to the visibility of the golf ball 2. Further, the core 4 does not hinder the visibility of the cover 6 and the paint layer 8 due to color development. Preferable white inorganic pigments include titanium dioxide, zinc oxide, barium sulfate, lithopone, lead white and calcium carbonate. In particular, titanium dioxide is preferable.

  From the viewpoint of visibility, the amount of the white inorganic pigment relative to 100 parts by mass of the base resin is preferably 1.0 part by mass or more, and particularly preferably 4.0 parts by mass or more. In light of durability, resilience, and moldability of the golf ball 2, this amount is preferably 10.0 parts by mass or less.

  The thickness of the mid layer 12 is preferably 0.2 mm or more, and particularly preferably 0.3 mm or more. The thickness of the intermediate layer 12 is preferably 2.5 mm or less, and particularly preferably 2.2 mm or less. The specific gravity of the intermediate layer 12 is preferably 0.90 or more, particularly preferably 0.95 or more. The specific gravity of the intermediate layer 12 is preferably 1.10 or less, and particularly preferably 1.05 or less.

  The cover 6 is made of a resin composition. The base polymer of this resin composition is an ionomer resin. The resin composition of the cover 6 can include the ionomer resin described above with respect to the mid layer 12.

  In the cover 6, an ionomer resin and another resin may be used in combination. Preferred resins that can be used in combination include binary copolymers of olefins and α, β-unsaturated carboxylic acids. Another preferred resin that can be used in combination with an ionomer resin is a terpolymer of an olefin, an α, β-unsaturated carboxylic acid, and an α, β-unsaturated carboxylic acid ester.

  Other resins may be used for the cover 6 instead of the ionomer resin. Examples of other resins include polyurethane, polystyrene, polyamide, polyester, and polyolefin. From the viewpoint of spin performance and scratch resistance, polyurethane is preferred. Two or more kinds of resins may be used in combination.

  The resin composition of the cover 6 includes a fluorescent pigment. This pigment emits a fluorescent color. In the golf ball 2, the color of the cover 6 can be observed through the paint layer 8. The fluorescent pigment affects the color of the golf ball 2. This golf ball 2 is excellent in visibility.

  Preferred fluorescent pigments include xanthene fluorescent pigments, acridine fluorescent pigments, quinoline fluorescent pigments, thiazole fluorescent pigments and aminoketone fluorescent pigments.

  As specific examples of fluorescent pigments, trade names “Epocolor FP-3000 (Yellow)”, “Epocolor FP-40 (Orange)”, “Epocolor FP-20 (Red)” and “Epocolor FP-10 ( Pin) ”.

  The amount of the fluorescent pigment is preferably 0.01 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the base resin. The golf ball 2 in which the amount of the fluorescent pigment is 0.01 parts by mass or more has excellent visibility. From this viewpoint, the amount of the fluorescent pigment is more preferably 0.1 parts by mass or more, and particularly preferably 1.0 part by mass or more. The golf ball 2 in which the amount of the fluorescent pigment is 5.0 parts by mass or less has high brightness and excellent visibility. The golf ball 2 having an amount of 5.0 parts by mass or less can be further obtained with excellent moldability and at low cost. From these viewpoints, the amount of the fluorescent pigment is particularly preferably 4.0 parts by mass or less.

  The resin composition of the cover 6 may include a white inorganic pigment. The resin composition of the cover 6 may include the white inorganic pigment described above with respect to the intermediate layer 12. The brightness of the cover 6 including the fluorescent pigment and the white inorganic pigment is large. This cover 6 can contribute to the visibility of the golf ball 2. From the viewpoint of visibility, the amount of the white inorganic pigment is preferably 0.05 parts by mass or more, particularly preferably 0.2 parts by mass or more with respect to 100 parts by mass of the base resin. The amount of the white inorganic pigment is preferably 5.0 parts by mass or less, and particularly preferably 0.5 parts by mass or less from the viewpoint that the concealing property is not too strong and the glittering property by the fluorescent pigment is sufficiently exhibited.

  The paint layer 8 covers the cover 6. The cover 6 is protected by the paint layer 8. The paint layer 8 achieves an excellent appearance of the golf ball 2. The paint layer 8 is formed by applying a paint. For the application, an electrostatic coating method, a spray gun method, a brush coating method, a dipping method, or the like can be employed.

  The paint consists of a resin composition. Examples of the base resin for the paint include polyurethane, epoxy resin, polyester, acrylic resin, and cellulose resin. From the viewpoint of the durability of the paint layer 8, a two-component curable polyurethane is preferable.

  A two-component curable polyurethane is obtained by a reaction between a main agent and a curing agent. A two-component curable polyurethane obtained by a reaction between a main component containing a polyol component and a curing agent containing a polyisocyanate (including a polyisocyanate derivative) is preferred.

  It is preferable that urethane polyol is used as the polyol component of the main agent. Urethane polyol has a urethane bond and two or more hydroxyl groups. Preferably, the urethane polyol has a hydroxyl group at its terminal. The urethane polyol can be obtained by reacting the polyol and the polyisocyanate at a ratio such that the hydroxyl group of the polyol component is excessive in molar ratio with respect to the isocyanate group of the polyisocyanate.

  The polyol used for the production of the urethane polyol has a plurality of hydroxyl groups. A polyol having a weight average molecular weight of 50 to 2,000, particularly 100 to 1,000 is preferred. Examples of the low molecular weight polyol include diol and triol. Specific examples of the diol include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol. Specific examples of the triol include glycerin, trimethylolpropane, and hexanetriol. High molecular weight polyols include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG) and polyoxytetramethylene glycol (PTMG); polyethylene adipate (PEA), polybutylene adipate (PBA) ) And polyhexamethylene adipate (PHMA); lactone polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. Two or more polyols may be used in combination.

The polyisocyanate used for the production of the urethane polyol has a plurality of isocyanate groups. Specific examples of the polyisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), and 4,4′-diphenylmethane diisocyanate (MDI). ), 1,5-naphthylene diisocyanate (NDI), 3,3′-vitrylene-4,4′-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI) and paraphenylene diisocyanate ( Aromatic polyisocyanates such as PPDI); 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), hydrogenated xylylene diisocyanate (H ₆ XDI) and isophorone diisocyanate (IPDI) ); And aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI). Two or more polyisocyanates may be used in combination. From the viewpoint of weather resistance, TMXDI, XDI, HDI, H ₆ XDI, IPDI and H ₁₂ MDI are preferred.

  A known catalyst can be used in the reaction of the polyol and the polyisocyanate for producing the urethane polyol. A typical catalyst is dibutyltin dilaurate.

  The ratio of the urethane bond contained in the urethane polyol is preferably from 0.1 mmol / g to 5 mmol / g. By the urethane polyol having this ratio of 0.1 mmol / g or more, the scratch resistance of the paint layer 8 can be achieved. By the urethane polyol having this ratio of 5 mmol / g or less, the followability of the paint layer 8 to the cover 6 can be achieved. In the paint layer 8 having excellent followability, cracks are less likely to occur when the golf ball 2 is repeatedly hit. By adjusting the molecular weight of the polyol used as a raw material, the ratio of urethane bonds can be set within the above range. The ratio of urethane bonds can be set within the above range also by adjusting the blending ratio of polyol and polyisocyanate.

  From the viewpoint that the time required for the reaction between the main agent and the curing agent is short, the weight average molecular weight of the urethane polyol is preferably 4000 or more, and more preferably 4500 or more. From the viewpoint of adhesion of the paint layer 8 to the cover 6, the weight average molecular weight is preferably 10,000 or less, and more preferably 9000 or less.

  From the viewpoint of the adhesion of the paint layer 8 to the cover 6, the hydroxyl value (mgKOH / g) of the urethane polyol is preferably 15 or more, and more preferably 73 or more. From the viewpoint that the time required for the reaction between the main agent and the curing agent is short and from the viewpoint of suppressing cracks, the hydroxyl value is preferably 130 or less, more preferably 120 or less.

  The main agent may contain a polyol having no urethane bond together with the urethane polyol. The aforementioned polyol, which is a raw material for urethane polyol, can be used as the main agent. Polyols that are compatible with urethane polyols are preferred. From the viewpoint that the time required for the reaction between the main agent and the curing agent is short, the ratio of the urethane polyol in the main agent is preferably 50% by mass or more and more preferably 80% by mass or more in terms of solid content. Ideally this ratio is 100% by weight.

  The curing agent contains polyisocyanate or a derivative thereof. The aforementioned polyisocyanate, which is a raw material of urethane polyol, can be used as a curing agent.

  The paint layer 8 contains a condensing fluorescent dye together with the base resin. The light-collecting fluorescent dye absorbs sunlight and develops long-wave fluorescence. The golf ball 2 provided with the paint layer 8 containing a condensing fluorescent dye has excellent visibility. The light-collecting fluorescent dye is excellent in compatibility with the base resin of the paint layer 8. The light-collecting fluorescent dye is particularly excellent in compatibility with polyurethane. In the paint layer 8, bleeding of the condensing fluorescent dye is suppressed. The paint layer 8 is excellent in weather resistance.

  Examples of preferred condensing fluorescent dyes include perylene dyes and naphthalimide dyes. Specific examples of the light-collecting fluorescent dye include trade names “LUMOGEN YELLOW 083”, “LUMOGEN ORANGE 240”, “LUMOGEN RED 305”, “LUMOGEN PINK 285” and “LUMOGEN VIOLET 570” of BASF.

  In the golf ball 2 according to this embodiment, the resin composition of the paint layer 8 does not contain a white inorganic pigment. The paint layer 8 is transparent. In general, the thickness of the paint layer 8 is much smaller than the thickness of the intermediate layer 12 and the cover 6. Even if the paint layer 8 contains a condensing fluorescent dye, the color of the cover 6 is reflected in the color of the golf ball 2. Due to the synergistic effect of the color of the cover 6 and the color of the paint layer 8, the golf ball 2 can achieve excellent visibility.

The product of the amount (parts by mass) of the condensing fluorescent dye and the thickness (mm) of the paint layer 8 with respect to 100 parts by mass of the base resin is referred to as a concealment index in this specification. The concealment index is greater than 4.0 × 10 ^{−5 and} less than 6.0 × 10 ⁻³ . In the golf ball 2 having a concealment index greater than 4.0 × 10 ⁻⁵ , the color of the paint layer 8 contributes to visibility. In this respect, the concealment index is particularly preferably 8.0 × 10 ⁻⁵ or more. The paint layer 8 having a concealment index smaller than 6.0 × 10 ⁻³ is excellent in transparency. In the golf ball 2 having a concealment index smaller than 6.0 × 10 ⁻³ , the color of the cover 6 contributes to visibility. In this respect, the concealment index is particularly preferably 1.0 × 10 ⁻³ or less.

  The amount of the condensing fluorescent dye with respect to 100 parts by mass of the base resin in the paint layer 8 is preferably 0.005 parts by mass or more and 0.20 parts by mass or less. In the golf ball 2 in which the amount is 0.005 parts by mass or more, the color of the paint layer 8 contributes to visibility. In this respect, the amount is particularly preferably equal to or greater than 0.010 parts by mass. The paint layer 8 having this amount of 0.20 parts by mass or less is excellent in transparency. In the golf ball 2 in which the amount is 0.20 parts by mass or less, the color of the cover 6 contributes to visibility. In this respect, the amount is particularly preferably equal to or less than 0.15 parts by mass.

  The thickness of the paint layer 8 is preferably 0.008 mm or greater and 0.030 mm or less. In the golf ball 2 having a thickness of 0.008 mm or more, the color of the paint layer 8 contributes to visibility. In this respect, the thickness is particularly preferably equal to or greater than 0.010 mm. In the golf ball 2 having a thickness of 0.030 mm or less, the color of the cover 6 contributes to visibility. In this respect, the thickness is particularly preferably equal to or less than 0.020 mm.

  It is preferable that the fluorescent pigment of the cover 6 and the condensing fluorescent dye of the paint layer 8 have similar colors. Excellent visibility is achieved by the synergistic effect of the fluorescent pigment having the same color and the light-collecting fluorescent dye.

  The color difference ΔE between the surface of the sphere composed of the core 4 and the cover 6 and the surface of the golf ball 2 is preferably 20 or less. In the golf ball 2 having the color difference ΔE within this range, excellent visibility is achieved by the synergistic effect of the fluorescent pigment of the cover 6 and the condensing fluorescent dye of the paint layer 8. In this respect, the color difference ΔE is particularly preferably 10 or less.

The color difference ΔE is calculated based on the following mathematical formula.
ΔE = ((ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ) ^1/2
In this equation, ΔL ^* is the difference between the sphere index L ^* and the golf ball 2 index L ^* . In this equation, Δa ^* is the difference between the spherical index a ^* and the golf ball 2 index a ^* . In this equation, Δb ^* is the difference between the spherical index b ^* and the golf ball 2 index b ^* . L ^* , a ^* and b ^* are indices in the CIELAB display system. The indices L ^* , a ^* and b ^* are calculated by the following mathematical formulas.
L ^* = 116 (Y / Yn) ¹ / 3-16
a ^* = 500 ((X / Xn) ¹ /3-(Y / Yn) ^1/3 )
b ^* = 200 ((Y / Yn) ¹ /3-(Z / Zn) ^1/3 )
In these mathematical formulas, X, Y, and Z are tristimulus values in the XYZ display system, and Xn, Yn, and Zn are tristimulus values on the perfect diffuse reflection surface. The CIELAB display system is a standard determined in 1976 by the International Commission on Illumination (CIE). In Japan, the CIELAB display system is adopted in “JIS Z 8729”. L ^* is a lightness index. a ^* and b ^* are indices that correlate with hue and saturation. The negative direction of a ^* is the green direction, and the positive direction is the red direction. The negative direction of b ^* is the blue direction, and the positive direction is the yellow direction. The index is measured with a color difference meter “CM-3500d” manufactured by Minolta. The light receiving portion is applied to the surface of the sphere or golf ball 2 and measurement is performed. “Standard light D ₆₅ ” is adopted as the light source. The color temperature of this light source is 6504k. As the spectral sensitivity, “2 ° field of view” is adopted. As the hole diameter, 8 mm is adopted.

  In the golf ball 2, the paint layer 8 contains a light-collecting fluorescent dye, and the cover 6 does not contain the light-collecting fluorescent dye. Therefore, the contamination of equipment is suppressed in the manufacturing process of the golf ball 2.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
100 parts by weight of high-cis polybutadiene (trade name “BR730” from JSR), 27 parts by weight of zinc acrylate, 0.5 parts by weight of diphenyl disulfide, 0.75 parts by weight of dicumyl peroxide and an appropriate amount of zinc oxide Were kneaded to obtain a rubber composition. This rubber composition was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at 170 ° C. for 20 minutes to obtain a center having a diameter of 39.1 mm. The amount of zinc oxide was adjusted so that the mass of the golf ball was 45.5 g.

  50 parts by weight of ionomer resin (Mitsui DuPont Polychemical, trade name “Himiran AM7329”), 25 parts by weight of other ionomer resin (Mitsui DuPont Polychemicals trade name “Himiran AM7337”), 25 parts by weight of styrene block The resin composition was obtained by kneading the contained thermoplastic elastomer (trade name “Lavalon T3221C” manufactured by Mitsubishi Chemical Corporation) and 10 parts by mass of titanium dioxide with a twin-screw kneading extruder. This resin composition was coated around the center by an injection molding method to form an intermediate layer. The thickness of this intermediate layer was 1.0 mm.

  70 parts by weight of an ionomer resin (previously referred to as “Himiran AM7329”), 30 parts by weight of an ethylene-methacrylic acid copolymer (trade name “Nucrel N1050H” from Mitsui DuPont Polychemical Co., Ltd.) and 3 parts by weight of a fluorescent pigment (see above “ Epocolor FP-3000 (Yellow)) was kneaded with a twin-screw kneading extruder to obtain a resin composition, which was coated around the intermediate layer by injection molding to form a cover. The thickness of was 0.8 mm.

  A paint having a two-component curable polyurethane as a base resin was prepared. The main component of this paint is a mixture of polyether polyol and polyester polyol. The hydroxyl value of this main agent is 82 mgKOH / g. The curing agent for this paint is hexamethylene diisocyanate. The NCO: OH equivalent ratio of this paint is 1.2: 1.0. This paint contains a light-collecting fluorescent dye ("LUMOGEN F YELLOW 083" described above). The amount of the condensing fluorescent dye is 0.02 parts by mass with respect to 100 parts by mass of the base resin. This paint was applied to the surface of the cover with a spray gun. This paint was dried at a temperature of 40 ° C. for 120 minutes to obtain a paint layer having a thickness of 0.01 mm. Thus, the golf ball of Example 1 having a diameter of 42.7 mm and a mass of about 45.5 g was obtained.

[Example 2-18 and Comparative Example 1-5]
Golf balls of Example 2-18 and Comparative Example 1-5 are obtained in the same manner as in Example 1 except that the specifications of the center, intermediate layer, cover, and paint layer are as shown in Table 6-10 below. It was. Details of the composition of the center are shown in Table 1 below. Details of the composition of the intermediate layer are shown in Table 2 below. Details of the composition of the cover are shown in Table 3 below. Details of the composition of the paint layer are shown in Tables 4-5 below.

[Visibility]
A golf ball was placed on the lawn. The visibility was evaluated by 10 golfers at a point 5 m away from the golf ball. The rating was based on the number of golfers rated as easy to see.
A: 9 or more B: 6 or more and 8 or less C: 4 or more and 5 or less D: 3 or less The results are shown in Tables 6 to 10 below.

[Contamination]
In the golf ball manufacturing process, the case where the equipment was not contaminated by the condensing fluorescent dye was rated as “A”, and the case where this contamination occurred was rated as “B”. The results are shown in Tables 6 to 10 below.

  As shown in Table 6-10, the evaluation of the golf ball of each example is high. From this evaluation result, the superiority of the present invention is clear.

  The golf ball according to the present invention can be used for playing at a golf course or practice at a practice field.

2 ... Golf ball 4 ... Core 6 ... Cover 8 ... Paint layer 10 ... Center 12 ... Intermediate layer 14 ... Dimple 16 ... Land

Claims (8)

A core, a cover covering the core, and a paint layer covering the cover;
The paint layer is molded from a resin composition containing a base resin and a light-collecting fluorescent dye,
The product of the amount of the condensing fluorescent dye with respect to 100 parts by mass of the base resin in the paint layer and the thickness (mm) of the paint layer is greater than 4.0 × 10 ^{−5 and} from 6.0 × 10 ⁻³ Small golf ball.   The golf ball according to claim 1, wherein the paint layer is transparent.   The golf ball according to claim 2, wherein the paint layer does not contain a white inorganic pigment.   The golf ball according to claim 1, wherein the cover is formed from a resin composition including a base resin and a fluorescent pigment.   The golf ball according to claim 4, wherein the resin composition of the cover contains 0.01 to 5.0 parts by mass of a fluorescent pigment with respect to 100 parts by mass of the base resin.   The golf ball according to claim 4, wherein the light-collecting fluorescent dye contained in the paint layer and the fluorescent pigment contained in the cover have a similar color.   The golf ball according to any one of claims 4 to 6, wherein the resin composition of the cover contains 0.05 to 5.0 parts by mass of a white inorganic pigment with respect to 100 parts by mass of the base resin.   The core is composed of a plurality of layers, and the outermost layer of the core is molded from a resin composition containing 100 parts by mass of a base resin and 1.0 part by mass or more and 10.0 parts by mass or less of a white inorganic pigment. The golf ball according to claim 1.

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