Golf balls

Abstract

To provide a golf ball which has high visibility, and has no discomfort in shot.SOLUTION: A golf ball 1 has a core, and a cover arranged on outside of the core. A surface of the golf ball has a first area S1 having a first color, and a second area S2 having a second color. A hue of the first color is H1 expressed using an H value by an HSL color space, a hue of the second color is H2 expressed using an H value by the HSL color space, and the H1 and the H2 satisfy a mathematical expression (1) or (2). The mathematical expression (1) is 0≤|H1-H2|≤60 and the mathematical expression (2) is 300≤|H1-H2|≤360.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a golf ball, and more particularly to a colored golf ball. [Background technology]

[0002] Normally, golf balls are white. In bad weather conditions such as rain, cloudiness, fog, and low light, it is difficult to follow the trajectory of a white golf ball and visually confirm the landing point of the golf ball. In addition, if a white golf ball lands on dead grass, it is difficult to find the golf ball even if you are close to it. Recently, more and more golf players are looking for fashionable golf balls. Under these circumstances, colored golf balls have been proposed to satisfy the demands for a fashionable appearance and visibility in bad weather.

[0003] Patent Document 1 discloses a method for manufacturing a two-tone golf ball in which a first hemispherical shell and a core are loaded into a lower mold having a hemispherical recess, the first hemispherical shell is covered with a second hemispherical shell of a different color from the first hemispherical shell to form a spherical shape, and then an upper mold is placed over the second hemispherical shell and molded under heat and pressure. The method is characterized in that a protrusion is provided near the open end face of the first hemispherical shell for horizontal engagement with the edge of the lower mold recess.

[0004] Patent Document 2 discloses a golf ball having a core and a cover, the cover being made of a first hemisphere and a second hemisphere, the specifications of the first hemisphere being different from those of the second hemisphere. The first hemisphere may be made of a first resin composition, and the second hemisphere may be made of a second resin composition, and the composition of the first resin composition may be different from the composition of the second resin composition.

[0005] Patent Document 3 discloses a golf ball having a core having at least one layer and a cover having at least one layer, wherein the outermost layer of the core has two hemispherical portions of different colors formed from a rubber composition, and the boundary between the hemispherical portions is provided as a color boundary line along a great circle of the outermost layer of the core, at least one of the hemispherical portions contains a fluorescent colorant or a lustrous agent, the cover is formed from a transparent or translucent thermoplastic resin composition, and at least one layer of the cover contains at least one of a fluorescent brightening agent, a fluorescent colorant, and a lustrous agent.

[0006] Patent Document 4 discloses a golf ball characterized in that the surface of the inner core is covered with a plurality of outer shells of different colors to form an outer shell layer, and the outer surface is divided by the difference in the colors of the outer shell layers.

[0007] Patent Document 5 discloses a golf ball having a multi-color layer obtained by injection molding a first material and a second material, respectively.

[0008] Patent Document 6 discloses a golf ball having at least two layers, each layer having areas of at least two different colors, thereby giving the overall appearance of the golf ball a multicolor appearance.

[0009] Patent Document 7 discloses a golf ball in which the first and second hemispherical covers have different color tones. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 63-38476 [Patent Document 2] JP 2013-183833 A [Patent Document 3] JP 2017-118950 A [Patent Document 4] Public Disclosure No. 59-64165 [Patent Document 5] U.S. Patent Publication No. 7,862,760 [Patent Document 6] U.S. Patent Publication No. 8,915,802 [Patent Document 7] U.S. Patent Publication No. 9,067,105 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a golf ball which is highly visible and causes little discomfort when shot. [Means for solving the problem]

[0012] The golf ball of the present invention, which has been able to solve the above problems, is a golf ball having a core and a cover disposed on the outside of the core, the surface of the golf ball having a first region of a first color and a second region of a second color; the hue of the first color is H1 expressed using an H value in the HSL color space; the hue of the second color is H2 expressed using an H value in the HSL color space; A golf ball characterized in that H1 and H2 satisfy the following formula (1) or (2). 0≦|H1-H2|≦60 (1) 300≦|H1-H2|≦360 (2)

[0013] When the relationship of the above formula (1) or formula (2) is satisfied, the first color of the first region and the second color of the second region are similar colors. As a result, there is less sense of incongruity when taking a shot, and it is easier to find the rough. Effect of the Invention

[0014] According to the present invention, a golf ball which has high visibility and causes little discomfort when shot can be obtained. [Brief description of the drawings]

[0015] [Figure 1] 1 is a front view illustrating a golf ball according to an embodiment of the present invention. [Diagram 2] 1 is a plan view illustrating a golf ball according to an embodiment of the present invention. [Diagram 3] 1 is a front view illustrating a golf ball according to an embodiment of the present invention. [Figure 4] 1 is a plan view illustrating a golf ball according to an embodiment of the present invention. [Diagram 5] 1 is a partially cutaway cross-sectional view showing a golf ball according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The golf ball of the present invention is a golf ball having a core and a cover disposed on the outside of the core, the surface of the golf ball having a first region of a first color and a second region of a second color; the hue of the first color is H1 expressed using an H value in the HSL color space; the hue of the second color is H2 expressed using an H value in the HSL color space; A golf ball characterized in that H1 and H2 satisfy the following formula (1) or (2). 0≦|H1-H2|≦60 (1) 300≦|H1-H2|≦360 (2)

[0017] The surface of the golf ball of the present invention has a first region of a first color and a second region of a second color different from the first color. It is preferable that the first region and the second region are each a single color region.

[0018] the hue of the first color of the first region is H1 expressed using an H value in the HSL color space; The hue of the second color in the second region is H2 expressed using an H value in the HSL color space, and the H1 and H2 satisfy the following formula (1) or (2). 0≦|H1-H2|≦60 (1) 300≦|H1-H2|≦360 (2) In the present invention, the "hue of the first color in the first region" may be simply referred to as the "hue of the first region," and the "hue of the second color in the second region" may be simply referred to as the "hue of the second region."

[0019] When the hue H1 of the first region and the hue H2 of the second region satisfy the above formula (1), the absolute value |H1-H2| of the difference between the hue H1 of the first region and the hue H2 of the second region is preferably 0 or more, more preferably more than 0, even more preferably 5 or more, particularly preferably 7 or more, preferably 60 or less, more preferably 55 or less, and even more preferably 50 or less. This is because, if the absolute value |H1-H2| is within the above range, visibility is high, and an effect of eliminating a sense of incongruity during a shot can be obtained.

[0020] When the hue H1 of the first region and the hue H2 of the second region satisfy the above formula (2), the absolute value |H1-H2| of the difference between the hue H1 of the first region and the hue H2 of the second region is preferably 300 or more, more preferably 305 or more, even more preferably 307 or more, preferably 360 or less, more preferably 355 or less, and even more preferably 350 or less. This is because, if the absolute value |H1-H2| is within the above range, visibility is high, and an effect of eliminating a sense of incongruity during a shot can be obtained.

[0021] The hue of the first color of the first region is H1, expressed using an H value in the HSL color space, and the H1 is preferably 20 or more, more preferably 30 or more, and even more preferably 40 or more, and is preferably 340 or less, more preferably 330 or less, and even more preferably 320 or less.

[0022] The saturation of the first color in the first region is S1, expressed using an S value in the HSL color space, and the S1 is preferably 40 or more, more preferably 45 or more, and even more preferably 50 or more, and is preferably 100 or less, more preferably 95 or less, and even more preferably 90 or less.

[0023] The luminance of the first color in the first region is L1 expressed using an L value in the HSL color space, and L1 is preferably 30 or more, more preferably 40 or more, and even more preferably 50 or more, and is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

[0024] The hue of the second color of the second region is H2, expressed using an H value in the HSL color space, and H2 is preferably 0 or greater, more preferably 5 or greater, and even more preferably 10 or greater, and is preferably 360 or less, and more preferably 350 or less.

[0025] The saturation of the second color of the second region is S2, expressed using an S value in the HSL color space, and the S2 is preferably 40 or more, more preferably 50 or more, and even more preferably 60 or more, and is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

[0026] The luminance of the second color of the second region is L2 expressed using an L value in the HSL color space, and L2 is preferably 30 or more, more preferably 40 or more, and even more preferably 50 or more, and is preferably 100 or less, more preferably 90 or less, and even more preferably 80 or less.

[0027] The first color of the first region is not particularly limited, but is preferably a color selected from the group consisting of white, yellow, orange, blue, red, pink, green, and black. The second color of the second region is not particularly limited, but is preferably a color selected from the group consisting of white, yellow, orange, blue, red, pink, green, and black, as long as it is a color different from the first color of the first region.

[0028] The area of ​​said one region on the surface of the golf ball is preferably 10% or more of the surface area of ​​the golf ball, more preferably 20% or more, and even more preferably 30% or more, and is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less.

[0029] The area of ​​the second region on the surface of the golf ball is preferably 10% or more of the surface area of ​​the golf ball, more preferably 20% or more, and even more preferably 30% or more, and is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less.

[0030] The area ratio of the first region to the second region is not particularly limited, but is preferably 20 / 80 or more, more preferably 30 / 70 or more, particularly preferably 50 / 50, and is preferably 80 / 20 or less, more preferably 70 / 30 or less.

[0031] The shapes of the first and second regions are not particularly limited, and examples of shapes that can be mentioned in plan view include polygonal shapes such as triangles, rectangles, pentagons, and hexagons, as well as trapezoids, circles, ellipses, etc. Note that character strings such as product names and ball numbers that are generally provided on the surface of golf balls do not correspond to the first and second regions of the present invention.

[0032] The first region and the second region may each be provided at a single location on the surface of the golf ball, or may be provided at a plurality of locations.

[0033] In the present invention, when the surface of a golf ball is formed only from a first region and a second region, for example, when the first region has a specific shape, the second region is a region other than the first region. For example, if the first region is a polygonal shape such as a triangle, a rectangle, a pentagon, or a hexagon, or a trapezoid, a circle, or an ellipse in a plan view, the second region is a region on the surface of the golf ball other than the first region.

[0034] In a preferred embodiment of the present invention, the first and second regions are each bounded by two boundaries connecting a first pole and a second pole on the surface of the golf ball, and are continuous from the first pole to the second pole. Here, the first pole and the second pole are each an intersection of a central axis passing through the center of the golf ball and the surface of the golf ball. It is preferable that the first and second regions are each hemispherical.

[0035] FIG. 1 is an explanatory diagram for explaining a preferred embodiment of the present invention with respect to the first region and the second region. The golf ball 1 has a first pole P1 and a second pole P2 where an axis passing through the center of the golf ball intersects with the golf ball surface. FIG. 1 is a front view in which the first pole P1 and the second pole P2 are arranged in the vertical direction and the first region is arranged in front. FIG. 2 is a plan view seen from the first pole P1. The first region S1 and the second region S2 are regions surrounded by two boundary lines L1 and L2 connecting the first pole P1 and the second pole P2 on the golf ball surface, respectively, and are regions that are continuous from the first pole to the second pole. In the embodiment of FIG. 1 and FIG. 2, the first region S1 forms one-third of the golf ball surface, and the second region S2 forms two-thirds of the golf ball surface.

[0036] Fig. 3 is an explanatory diagram for explaining another preferred embodiment of the present invention with respect to the first region and the second region. Fig. 3 is a front view in which the first pole P1 and the second pole P2 are arranged in the vertical direction, and the boundary line L1 between the first region S1 and the second region S2 is arranged in the front. Fig. 4 is a plan view seen from the first pole P1. The surface of the golf ball is composed of the first region S1 and the second region S2, and the first region S1 and the second region S2 are each hemispherical.

[0037] The first and second regions may each be formed by a colored coating film, or may each be formed by a colored cover. For example, the first and second regions may be formed by a colored cover, the first and second regions may be formed by a colored coating film, or one of the first and second regions may be formed by a colored cover and the other of the first and second regions may be formed by a colored coating film.

[0038] The golf ball of the present invention may have at least one intermediate layer between the core and the cover. The hue of the outermost intermediate layer is H0 expressed using an H value in the HSL color space, and it is preferable that one of |H0-H1| and |H0-H2| is less than 10 and the other is 10 or more. When there are multiple intermediate layers, the outermost layer is the intermediate layer located closest to the cover. When the intermediate layer is a single layer, the outermost layer is the single intermediate layer.

[0039] Either |H0-H1| or |H0-H2| is preferably less than 10, more preferably equal to or less than 7, and even more preferably equal to or less than 4. When either |H0-H1| or |H0-H2| is less than 10, color development is good and an appearance in which the outlines of the dimples are not noticeable can be achieved.

[0040] The other of |H0-H1| and |H0-H2| is preferably 10 or more, preferably 20 or more, more preferably 30 or more, preferably 85 or less, more preferably 75 or less, and even more preferably 65 or less. When the other of |H0-H1| and |H0-H2| is 10 or more, the distinction between the first region and the second region becomes clear while maintaining color development.

[0041] The hue of the outermost layer of the intermediate layers is H0, expressed using an H value in the HSL color space, and the H0 is preferably 0 or more, more preferably 10 or more, and even more preferably 20 or more, and is preferably 360 or less, more preferably 350 or less, and even more preferably 340 or less.

[0042] The saturation of the outermost layer of the intermediate layers is S0, expressed using an S value in the HSL color space, and the S0 is preferably 30 or more, more preferably 40 or more, and even more preferably 50 or more, and is preferably 100 or less, more preferably 97 or less, and even more preferably 94 or less.

[0043] The luminance of the outermost layer of the intermediate layers is L0 expressed using the L value in the HSL color space, and the L0 is preferably 30 or more, more preferably 40 or more, and even more preferably 50 or more, and is preferably 100 or less, more preferably 97 or less, and even more preferably 94 or less.

[0044] The colors of the surface and the outermost intermediate layer of the golf ball of the present invention can be determined by the L*, a*, and b* values ​​in the CIELAB color system. The L*, a*, and b* values ​​in the CIELAB color system can be measured in accordance with JIS-Z-8701 or JIS-Z-8728. For the measurements, it is preferable to use a Minolta color difference meter CM-350d that employs a direct reading method of stimulus values. The tristimulus values ​​X, Y, and Z are converted to L*, a*, and b* as follows: 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 ] XN, YN, ZN: Tristimulus values ​​in the X, Y, Z system of a perfect diffuse reflecting surface

[0045] In the present invention, the L*, a*, and b* values ​​obtained as described above are converted into H value (hue), S value (saturation), and L value (brightness) in the HSL color space using a color code conversion tool. For example, the color code conversion tool described on the following website can be used. https: / / syncer.jp / color-converter

[0046] [Golf ball materials] The golf ball of the present invention comprises a core, at least one intermediate layer enclosing the core, and a cover enclosing the intermediate layer. The materials constituting each component of the golf ball will now be described.

[0047] [Middle layer and cover] The intermediate layer and / or cover of the golf ball of the present invention are formed from a composition containing a resin component. In the present invention, the resin composition forming the intermediate layer may be referred to as an intermediate layer composition, and the resin composition forming the cover may be referred to as a cover composition. Examples of the resin component include ionomer resin, thermoplastic polyurethane elastomer commercially available from BASF Japan Ltd. under the trade name "Elastollan (registered trademark)", thermoplastic polyamide elastomer commercially available from Arkema Co., Ltd. under the trade name "Pebax (registered trademark)", thermoplastic polyester elastomer commercially available from DuPont-Toray Co., Ltd. under the trade name "Hytrel (registered trademark)", and thermoplastic styrene elastomer commercially available from Mitsubishi Chemical Corporation under the trade name "Tefabloc".

[0048] Examples of the ionomer resin include a binary copolymer of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, in which at least a part of the carboxyl groups is neutralized with a metal ion, a ternary copolymer of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester, in which at least a part of the carboxyl groups is neutralized with a metal ion, or a mixture thereof. The olefin is preferably an olefin having 2 to 8 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, etc., and ethylene is particularly preferred. Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, etc., and acrylic acid or methacrylic acid is particularly preferred. Examples of the α,β-unsaturated carboxylic acid ester include methyl, ethyl, propyl, n-butyl, and isobutyl esters of acrylic acid, methacrylic acid, fumaric acid, and maleic acid, and acrylic acid esters and methacrylic acid esters are particularly preferred. Among these, the ionomer resin is preferably a metal ion neutralized product of an ethylene-(meth)acrylic acid binary copolymer or a metal ion neutralized product of an ethylene-(meth)acrylic acid-(meth)acrylic acid ester ternary copolymer.

[0049] The resin composition constituting the intermediate layer or cover of the golf ball of the present invention preferably contains a thermoplastic polyurethane elastomer or an ionomer resin as a resin component. When an ionomer resin is used, it is also preferable to use a thermoplastic styrene elastomer in combination. The content of the polyurethane or ionomer resin in the resin component of the resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0050] In a preferred embodiment of the present invention, the intermediate layer is formed from a composition containing an ionomer resin, and the cover is formed from a composition containing a thermoplastic urethane elastomer.

[0051] [Dyes and / or pigments] The intermediate layer and / or cover of the golf ball of the present invention preferably contains a dye and / or a pigment, and more preferably contains a fluorescent dye and / or a fluorescent pigment. The fluorescent dye may be either organic or inorganic, and may be any commercially available fluorescent dye. Examples of the fluorescent dye include thioxanthene derivatives, xanthen derivatives, perylene derivatives, peryleneimide derivatives, coumarin derivatives, thioindigo derivatives, naphthalimide derivatives, and methine derivatives.

[0052] In a preferred embodiment, the melting point of the fluorescent dye and / or fluorescent pigment is 180° C. or lower, more preferably 175° C. or lower, even more preferably 170° C. or lower, and is preferably at least 135° C. or higher, more preferably 140° C. or higher, and even more preferably 145° C. or higher. If the melting point of the fluorescent dye and / or fluorescent pigment is within the above range, the fluorescent dye and / or fluorescent pigment can be mixed and dispersed in the resin component at a relatively low temperature. Since discoloration due to high temperatures during processing is unlikely to occur, the desired color tone can be easily obtained.

[0053] The fluorescent dye is not particularly limited, and specific examples thereof, by trade name, include yellow fluorescent dyes such as Lumogen F Orange.TM. 240 (manufactured by BASF); Lumogen F Yellow.TM. 083 (manufactured by BASF); Hostasol Yellow.TM. 3G (manufactured by Hoechst-Celanese); Oraset Yellow.TM. 8GF (manufactured by Ciba-Geigy); Fluorol 088.TM. (manufactured by BASF); Thermoplast F Yellow.TM. 084 (manufactured by BASF); Golden Yellow.TM. D-304 (manufactured by DayGlo); Mohawk Yellow.TM. D-299 (manufactured by DayGlo); Potomac Yellow.TM. D-838 (manufactured by DayGlo); and Polyfast Brilliant Red.TM. SB (manufactured by Keystone).

[0054] The fluorescent pigment may be, for example, a pigment in which a fluorescent dye is dispersed in a polymer material, or a pigment in which a fluorescent dye is molded into particles. The fluorescent pigment is not particularly limited, but may be, for example, ZQ-11, ZQ-12, ZQ-13, ZQ-14, ZQ-15, ZQ-16, ZQ-17-N, ZQ-18, ZQ-19, ZQ-21, GPL-11, GPL-13, GPX-14, GPL-15, GPX-17, GPL-19, GPL-21 manufactured by Dayglo Color Co., Ltd., and FZ-2000 series, FZ-5000 series, FZ-6000 series, FZ-3040 series, FX-300 series, etc. manufactured by Shinroihi Co., Ltd.

[0055] Examples of polymer materials in which fluorescent dyes can be dispersed include benzoguanamine resins, acrylic resins, and polyester resins.

[0056] In a preferred embodiment, the cover and at least one intermediate layer contain, per 100 parts by weight of the resin component, preferably 0.5 parts by weight or more, more preferably 0.6 parts by weight or more, even more preferably 0.7 parts by weight or more, preferably 7 parts by weight or less, more preferably 6 parts by weight or less, even more preferably 5 parts by weight or less, and even more preferably 4 parts by weight or less of the dye and / or pigment. If the content is too high, the color of the golf ball will be too deep and dull, and if the content is too low, the desired color tone will not be obtained.

[0057] The fluorescent dye and / or fluorescent pigment has low light stability, so it is preferable to use an ultraviolet absorber or light stabilizer. The ultraviolet absorber or light stabilizer is not particularly limited and may be any commercially available product. For example, ultraviolet absorbers such as salicylic acid derivatives, benzophenone derivatives, benzotriazole derivatives, cyanoacrylate derivatives, triazine derivatives, and nickel complexes, and light stabilizers such as hindered amine derivatives can be mentioned.

[0058] Examples of ultraviolet absorbers of salicylic acid derivatives include phenyl salicylate, pt-butylphenyl salicylate, and p-octylphenyl salicylate; examples of ultraviolet absorbers of benzophenone derivatives include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, and 2,2-dihydroxy-4,4'-methoxybenzophenone; examples of ultraviolet absorbers of benzotriazole derivatives include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-[2-hydroxy-3,5-bis(α,α'-dimethylbenzyl)phenyl] ... phenyl]-2H-benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, etc.; cyanoacrylate derivative ultraviolet absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate, etc.; triazine derivative ultraviolet absorbers include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine, 2-(4-{[2-hydroxy-3-(2'-ethyl)hexyl]oxy}-2-hydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, etc. Specific examples include "Sumisorp 130" and "Sumisorp 140" (both benzophenone-based ultraviolet absorbers) manufactured by Sumitomo Chemical Co., Ltd., "TINUVIN 234", "TINUVIN 900", "TINUVIN 326", and "TINUVIN P" (all benzotriazole-based) manufactured by Chiba Specialty Chemicals Co., Ltd., "Uvinul N-35" (cyanoacrylate-based) manufactured by BASF Co., Ltd., and "TINUVIN 1577", "TINUVIN 460", and "TINUVIN 405" (triazine-based) manufactured by Chiba Specialty Chemicals Co., Ltd. These ultraviolet absorbers may be used alone or in combination of two or more kinds.However, the ultraviolet absorbing agents usable in the present invention are not limited to these, and any conventionally known ultraviolet absorbing agents can be used.

[0059] Examples of light stabilizers such as hindered amine derivatives include bis(1,2,2,6,6-pentamethyl-4-piperidyl){[3,5-bis(1,1'-dimethylethyl)-4-hydroxyphenyl]methyl}butylmalonate, 1-{2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl}-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, etc. Specific examples include "Sanol LS-2626" and "Tinuvin 144" manufactured by Ciba Specialty Chemicals.

[0060] The content of the ultraviolet absorber or light stabilizer is preferably 0.02 parts by mass or more, more preferably 0.04 parts by mass or more, and preferably 2 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the resin component of the intermediate layer or cover. If the content of the ultraviolet absorber or light stabilizer is within the above range, discoloration due to exposure to sunlight can be effectively suppressed.

[0061] (Titanium dioxide) The intermediate layer and / or the cover may contain titanium oxide. By combining a fluorescent pigment with a small amount of titanium oxide, a translucent cover having a vivid color can be obtained. Since the titanium oxide has high concealing properties, the content of titanium oxide is preferably 0.001 parts by mass or more, more preferably 0.002 parts by mass or more, even more preferably 0.005 parts by mass or more, preferably 0.7 parts by mass or less, preferably 0.5 parts by mass or less, and even more preferably 0.4 parts by mass or less, relative to 100 parts by mass of the resin component. If the content of titanium oxide is 0.001 parts by mass or more, a translucent cover having a vivid color can be obtained, and if the content of titanium oxide is more than 0.7 parts by mass, the cover tends to show concealing properties.

[0062] In order to increase the concealing property of the intermediate layer and / or the cover and to increase the degree of whiteness, the content of titanium oxide can be increased. In this case, the content of titanium oxide is preferably more than 0.7 parts by mass, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, based on 100 parts by mass of the resin components constituting the intermediate layer and / or the cover. By making the content of titanium oxide more than 0.7 parts by mass, the concealing property of the intermediate layer and / or the cover can be increased. In addition, if the content of titanium oxide is more than 10 parts by mass, the durability of the obtained intermediate layer and / or the cover may decrease.

[0063] (Other ingredients) In addition to the components mentioned above, the intermediate layer and / or cover may contain weight adjusters such as zinc oxide, calcium carbonate, and barium sulfate, dispersants, antioxidants, fluorescent brighteners, lubricants, light stabilizers, etc., within limits that do not impair the performance of the intermediate layer and / or cover.

[0064] The golf ball of the present invention preferably has a coating film covering the cover. When the golf ball of the present invention has a coating film, the color of the golf ball surface is obtained by measuring the surface of the coating film provided on the golf ball surface. Examples of the coating film include a colorless and transparent clear coating film, a colored opaque coating film, and a matte coating film.

[0065] If the golf ball has a colorless, transparent clear coating, the first color of the first region and the second color of the second region of the golf ball surface will reflect the color of the cover. If the golf ball has a colored opaque or matte coating, the color of the golf ball surface will be influenced by the coating.

[0066] The colored opaque coating film preferably contains, for example, a resin component and a dye and / or a pigment, and the matte coating film preferably contains, for example, a resin component and a filler.

[0067] The resin component constituting the coating film is not particularly limited, and acrylic resin, epoxy resin, polyurethane, polyester, cellulose-based resin, etc. can be used, but it is preferable to use a two-component curing polyurethane described below, because the use of a two-component curing polyurethane can provide a coating film layer with even greater durability.

[0068] (Polyurethane) The polyurethane is preferably a polyurethane (two-component curing polyurethane) obtained by reacting a polyol composition with a polyisocyanate composition.

[0069] (Polyol Composition) The polyol composition contains a polyol compound. The polyol compound includes a compound having two or more hydroxyl groups in the molecule. The polyol compound includes a compound having a hydroxyl group at the end of the molecule, and a compound having a hydroxyl group at a site other than the end of the molecule. The polyol compound may be used alone or in combination of two or more kinds.

[0070] Examples of the compound having a hydroxy 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 polyols include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and triols such as glycerin, trimethylolpropane, 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 polyols include polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG). Examples of the polyester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA). The polycaprolactone polyol may be poly-ε-caprolactone (PCL), etc. The polycarbonate polyol may be polyhexamethylene carbonate, etc.

[0071] The polyol composition preferably contains a urethane polyol as a polyol component. The urethane polyol is synthesized by the reaction of a polyisocyanate with a polyol. The polyisocyanate used for synthesizing the urethane polyol is not particularly limited as long as it has two or more isocyanate groups, and examples thereof include aromatic polyisocyanates such as 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), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of suitable polyisocyanates include alicyclic polyisocyanates or aliphatic polyisocyanates such as TMXDI, XDI, HDI, H6XDI, IPDI, and norbornene diisocyanate (NBDI), or mixtures of two or more of these. Among these, non-yellowing polyisocyanates (TMXDI, XDI, HDI, H6XDI, IPDI, H 12 MDI, NBDI, etc.) are preferably used.

[0072] The polyol used in the production of the urethane polyol is not particularly limited as long as it has a plurality of hydroxyl groups, and examples thereof include low molecular weight polyols and high molecular weight polyols. Examples of the low molecular weight polyols include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol; and triols such as glycerin, trimethylolpropane, and hexanetriol. Examples of high molecular weight polyols include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); condensation polyester polyols such as 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. Among the above polyols, those having a weight average molecular weight of 50 to 2,000, particularly about 100 to 1,000, are preferably used. These polyols may be used alone or in combination of two or more.

[0073] The urethane polyol is a polyol having a hydroxyl group at the end, which is formed by reacting the polyisocyanate with the polyol to form a urethane bond. The ratio of the urethane bond in the urethane polyol is preferably 0.1 mmol to 5 mmol per 1 g of the urethane polyol. The ratio of the urethane bond is related to the rigidity of the coating film formed, and if it is less than 0.1 mmol / g, the urethane concentration in the coating film formed is low, which may result in insufficient abrasion resistance. On the other hand, if it exceeds 5 mmol / g, the coating film becomes too hard, which reduces the ability to follow the deformation of the golf ball body, and makes it more likely to crack.

[0074] The weight-average molecular weight of the urethane polyol is preferably 4,000 or more, more preferably 4,500 or more, and preferably less than 10,000, more preferably 9,000 or less. If it is less than 4,000, it takes a long time to dry, which reduces workability and productivity. On the other hand, if the urethane polyol has a high molecular weight of 10,000 or more, the hydroxyl value of the urethane polyol is relatively small, and the reaction amount after application is reduced, which reduces the adhesion to the base. If the weight-average molecular weight is 9,000 or less, a dense coating film (or clear paint layer) with little loss of adhesion can be formed even in a state where it is wet with water.

[0075] The hydroxyl value of the urethane polyol is preferably 15 mgKOH / g or more, more preferably 25 mgKOH / g or more, and preferably 130 mgKOH / g or less, and more preferably 120 mgKOH / g or less. If it is less than 15 mgKOH / g, the amount of reaction with the curing agent is insufficient, and it may be difficult to obtain sufficient adhesive strength with the ball body. On the other hand, if it exceeds 130 mgKOH / g, it takes a long time to react with the curing agent, which increases the drying time, reducing productivity and making the ball more susceptible to cracking upon impact.

[0076] The above-mentioned urethane polyol is obtained by reacting the raw material polyol and polyisocyanate in such a ratio that the hydroxyl group of the polyol component is in excess of the isocyanate group of the polyisocyanate component in terms of molar ratio. In the above reaction, a solvent or a catalyst known for urethane reaction (such as dibutyltin dilaurate) can be used. The ratio of urethane bonds can be adjusted by adjusting the molecular weight of the raw material polyol and the compounding ratio of the polyol and polyisocyanate.

[0077] The polyol component contained in the polyol composition is preferably the above-mentioned specific urethane polyol itself, but may contain a polyol that is compatible with the urethane polyol and does not have a urethane bond other than the urethane polyol. In this case, the polyol that does not have a urethane bond is not particularly limited, and the above-mentioned raw material polyol for synthesizing the urethane polyol can be used. In addition, when the polyol composition contains a polyol that does not have a urethane bond, the content of the urethane polyol in the polyol component contained in the polyol composition is preferably 50% by mass or more, more preferably 80% by mass or more. If the content of the urethane polyol in the polyol component is less than 50% by mass, the content of the urethane polyol is relatively low, and the drying time is long.

[0078] Examples of the compound having a hydroxy group other than at the terminal of the molecule include modified polyrotaxane having a hydroxy group, and hydroxy group-modified vinyl chloride-vinyl acetate copolymer.

[0079] The modified polyrotaxane having a hydroxyl group comprises a cyclodextrin, a linear molecule inserted into the cyclic structure of the cyclodextrin, and blocking groups arranged at both ends of the linear molecule to prevent the cyclic molecule from being detached. The polyrotaxane has viscoelasticity because the cyclodextrin molecules pierced through the linear molecule in a skewered manner can move along the linear molecule (pulley effect), and even if tension is applied, the tension can be uniformly dispersed by the pulley effect, so that the polyrotaxane has the excellent property of being extremely unlikely to crack or scratch, unlike conventional crosslinked polymers.

[0080] The cyclodextrin is a general term for oligosaccharides having a cyclic structure. For example, cyclodextrin is a compound in which 6 to 8 D-glucopyranose residues are cyclically bonded by α-1,4-glucosidic bonds. Examples of cyclodextrin include α-cyclodextrin (number of glucose residues: 6), β-cyclodextrin (number of glucose residues: 7), and γ-cyclodextrin (number of glucose residues: 8), and α-cyclodextrin is preferred. The cyclodextrin may be used alone or in combination of two or more kinds.

[0081] The linear molecule is not particularly limited as long as it is a linear molecule that holds the cyclic structure of cyclodextrin in a skewered state, slidably and rotatably. The linear molecule can be polyalkylene, polyester, polyether, polyacrylic, etc., among which polyether is preferred, and polyethylene glycol is particularly preferred. Polyethylene glycol has small steric hindrance and can hold the cyclic structure of cyclodextrin in a skewered state.

[0082] The weight average molecular weight of the linear molecule is preferably 5,000 or more, more preferably 6,000 or more, and is preferably 100,000 or less, more preferably 80,000 or less.

[0083] The linear molecule preferably has a functional group at each end. By having the functional group, it can easily react with the blocking group. Examples of the functional group include a hydroxy group, a carboxy group, an amino group, and a thiol group.

[0084] The blocking groups are not particularly limited as long as they are arranged at both ends of the linear molecule and can prevent cyclodextrin from being detached from 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. Examples of the bulky blocking group include cyclodextrin and adamantyl groups. The number of cyclodextrins held by the linear molecule (retention amount) is preferably 0.06 to 0.61, more preferably 0.11 to 0.48, and even more preferably 0.24 to 0.41, assuming that the maximum retention amount is 1. If it is less than 0.06, the pulley effect may not be expressed, and if it exceeds 0.61, the cyclodextrins may be arranged too densely, reducing the mobility of the cyclodextrins.

[0085] The polyrotaxane is preferably one in which at least a part of the hydroxyl groups of cyclodextrin is modified with a caprolactone chain. By modifying with caprolactone, the steric hindrance between the polyrotaxane and the polyisocyanate is alleviated, and the reaction efficiency with the polyisocyanate is increased.

[0086] The modification may be, for example, hydroxyl groups of cyclodextrin treated with propylene oxide to hydroxypropylate them. Then, ε-caprolactone is added to carry out ring-opening polymerization. This modification results in a caprolactone chain -(CO(CH2)5O)nH (n is a natural number of 1 to 100) being bonded to the outside of the cyclic structure of cyclodextrin via a -O-C3H6-O- group. n represents the degree of polymerization and is preferably a natural number of 1 to 100, more preferably a natural number of 2 to 70, and even more preferably a natural number of 3 to 40. A hydroxyl group is formed at the other end of the caprolactone chain by ring-opening polymerization. The terminal hydroxyl group of the caprolactone chain can react with polyisocyanate.

[0087] The ratio of the hydroxyl groups modified with the caprolactone chain to the total hydroxyl groups (100 mol%) of the cyclodextrin before modification is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more. When the ratio of the hydroxyl groups modified with the caprolactone chain is within the above range, the hydrophobicity of the polyrotaxane is increased, and the reactivity with the polyisocyanate is increased.

[0088] The hydroxyl value of the polyrotaxane is preferably 10 mgKOH / g or more, more preferably 15 mgKOH / g or more, even more preferably 20 mgKOH / g or more, and is preferably 400 mgKOH / g or less, more preferably 300 mgKOH / g or less, even more preferably 220 mgKOH / g or less, and particularly preferably 180 mgKOH / g or less. If the hydroxyl value of the polyrotaxane is within the above range, the reactivity with polyisocyanate is high, and the durability of the coating film is good.

[0089] The total molecular weight of the polyrotaxane is preferably 30,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more, and is preferably 3,000,000 or less, more preferably 2,500,000 or less, and even more preferably 2,000,000 or less, in terms of weight average molecular weight. If the weight average molecular weight is 30,000 or more, the coating film has sufficient strength, and if it is 3,000,000 or less, the coating film has sufficient softness, and the approach performance of the golf ball is improved. The weight average molecular weight of the polyrotaxane may be measured, 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" manufactured by Showa Denko KK) as a column.

[0090] Specific examples of polyrotaxane modified with polycaprolactone include SeRM Super Polymer SH3400P, SH2400P, and SH1310P manufactured by Advanced Soft Materials.

[0091] The hydroxyl-modified vinyl chloride-vinyl acetate copolymer can adjust the adhesion while maintaining the scratch resistance of the coating film. The hydroxyl-modified vinyl chloride-vinyl acetate copolymer can be obtained, for example, by copolymerizing vinyl chloride, vinyl acetate, and a monomer having a hydroxyl group (e.g., polyvinyl alcohol, hydroxyalkyl acrylate), or by partially or completely saponifying the vinyl chloride-vinyl acetate copolymer.

[0092] In the hydroxyl group-modified vinyl chloride-vinyl acetate copolymer, the content of the vinyl chloride component is preferably 1 mass % or more, more preferably 20 mass % or more, even more preferably 50 mass % or more, and is preferably 99 mass % or less, more preferably 95 mass % or less. Specific examples of the hydroxyl group-modified vinyl chloride-vinyl acetate copolymer include Solvine (registered trademark) A, Solvine AL, and Solvine TA3 manufactured by Nissin Chemical Industry Co., Ltd.

[0093] The polyol composition is preferably an embodiment (embodiment 1) containing a urethane polyol containing, as a constituent, a polyether diol having a number average molecular weight of 600 to 3000; or an embodiment (embodiment 2) containing a polyrotaxane having cyclodextrin, a linear molecule inserted into the cyclic structure of the cyclodextrin, and blocking groups arranged at both ends of the linear molecule to prevent the cyclodextrin from being detached, in which at least a portion of the hydroxyl groups of the cyclodextrin are modified with a caprolactone chain via a -O-C3H6-O- group.

[0094] (Polyisocyanate composition) The polyisocyanate component of the polyisocyanate composition may, for example, be a compound having at least two isocyanate groups. Examples of the polyisocyanate include aromatic polyisocyanates such as 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), and paraphenylene diisocyanate (PPDI); 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples of the polyisocyanate include alicyclic polyisocyanates or aliphatic polyisocyanates such as cycloaliphatic polyisocyanate (MDI), hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI); and derivatives of these polyisocyanates. In the present invention, two or more kinds of polyisocyanates may be used as the polyisocyanate.

[0095] Examples of the polyisocyanate derivatives include adduct modified products obtained by reacting diisocyanate with polyhydric alcohol; isocyanurate modified products of diisocyanate; biuret modified products; and allophanate modified products. Of these, those from which free diisocyanate has been removed are more preferred.

[0096] The colored coating contains, per 100 parts by mass of the resin components constituting the coating, preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.7 parts by mass or more, preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, even more preferably 2.2 parts by mass or less, and even more preferably 2.0 parts by mass or less of the dye and / or pigment. If the content is too high, the color of the golf ball will be too deep and will have a dull tone, and if the content is too low, the desired tone will not be obtained.

[0097] The colored opaque coating film may contain titanium oxide to enhance the hiding power. In this case, the content of titanium oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, based on 100 parts by mass of the resin components constituting the coating film. By making the content of titanium oxide 0.5 parts by mass or more, the coating film can be given hiding power. In addition, if the content of titanium oxide exceeds 10 parts by mass, the durability of the obtained coating film may decrease.

[0098] The coating film of the golf ball of the present invention preferably contains a filler. If a filler is contained, the appearance of the coating film may become matte.

[0099] The filler may be a filler generally used in paints. Examples of the filler include silica (e.g., wet silica such as fused silica, dry silica, precipitated silica, silica gel, and colloidal silica), diatomaceous earth, zeolite, perlite, mica, glass, wollastonite, potassium titanate, xonotlite, gypsum, aluminum borate, molybdenum disulfide, aramid, crystalline cellulose, alumina, carbon, metal particles, and metal oxide particles.

[0100] It is also preferable to use a porous filler as the filler. The porous filler has a large number of pores. The shape of the pores of the porous filler is not particularly limited. The pore size of the pores of the porous filler is not particularly limited, but is preferably 0.1 nm to 500 nm. The pore size of the pores of the porous filler varies depending on the type of the porous filler, and for example, the pore size of the zeolite type is 0.1 nm to 2 nm, and the diatomaceous earth is about 300 nm.

[0101] Examples of the porous filler include diatomaceous earth, zeolite, and perlite. Diatomaceous earth is a muddy soil formed by the accumulation and fossilization of the remains of diatoms, a type of plankton, on the bottom of the sea or lake. It is mainly composed of silica, and each particle has many microscopic mechanisms. Perlite is a porous body formed by subjecting glassy volcanic rocks such as obsidian, pearlite, and rosinite to high heat treatment to evaporate the water contained in the volcanic rocks. Zeolite is a crystalline porous aluminosilicate. Examples of the structure of zeolite include A-type, ferrierite, ZSM-5, mordenite, beta, X-type, and Y-type. Zeolite also includes porous silicalite. The porous filler may be used alone or in combination of two or more types.

[0102] The volume average particle diameter of the filler is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 2.0 μm or more, and is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. The volume particle size distribution is measured by laser diffraction, and the 50% cumulative particle diameter (D50) in the volume particle size distribution is defined as the volume average particle diameter.

[0103] The content of the filler in the coating film is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of the resin component, and is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and even more preferably 120 parts by mass or less. If the content of the filler is 3 parts by mass or more, the appearance is matte, and if it is 200 parts by mass or less, the appearance is good and adhesion of dirt can be reduced.

[0104] The coating film may further contain additives that can be generally contained in golf paints, such as ultraviolet absorbers, antioxidants, light stabilizers, fluorescent brighteners, antiblocking agents, etc. The ultraviolet absorbers and light stabilizers exemplified as those that can be blended in the intermediate layer and / or cover can also be used in the coating film.

[0105] [core] A known rubber composition (hereinafter, sometimes simply referred to as the "rubber composition for the core") can be used for the core of the golf ball of the present invention. For example, a rubber composition containing a base rubber, a co-crosslinking agent, and a crosslinking initiator can be molded by hot pressing.

[0106] As the base rubber, it is preferable to use high-cis polybutadiene having cis bonds of 40% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, which is advantageous in terms of resilience. As the co-crosslinking agent, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof is preferable, and a metal salt of acrylic acid or a metal salt of methacrylic acid is more preferable. As the metal of the metal salt, zinc, magnesium, calcium, aluminum, and sodium are preferable, and zinc is more preferable. The amount of the co-crosslinking agent used is preferably 20 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the base rubber. When an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms is used as the co-crosslinking agent, it is preferable to compound a metal compound (for example, magnesium oxide). As the crosslinking initiator, an organic peroxide is preferably used. Specifically, organic peroxides such as dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide, etc., can be mentioned, and among these, dicumyl peroxide is preferably used. The amount of the crosslinking initiator is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, based on 100 parts by mass of the base rubber.

[0107] The core rubber composition may further contain an organic sulfur compound. As the organic sulfur compound, diphenyl disulfides, thiophenols, and thionaphthols can be suitably used. The amount of the organic sulfur compound is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, per 100 parts by mass of the base rubber. The core rubber composition may further contain a carboxylic acid and / or a salt thereof. As the carboxylic acid and / or a salt thereof, a carboxylic acid having 1 to 30 carbon atoms and / or a salt thereof is preferred. 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 a salt thereof is 1 part by mass or more and 40 parts by mass or less, per 100 parts by mass of the base rubber.

[0108] [Manufacturing method of golf balls] The core of the golf ball of the present invention is molded, for example, by hot pressing the rubber composition for the core. The hot press molding conditions for the rubber composition for the core may be appropriately set depending on the rubber composition, but are usually performed at 130°C to 200°C and a pressure of 2.9MPa to 11.8MPa for 10 minutes to 60 minutes. For example, it is preferable to heat the rubber composition for the core at 130°C to 200°C for 10 minutes to 60 minutes, or to heat it in two stages at 130°C to 150°C for 20 minutes to 40 minutes and then at 160°C to 180°C for 5 minutes to 15 minutes.

[0109] The intermediate layer composition and the cover composition can be obtained, for example, by dry blending the resin component, the dye and / or pigment, and additives that are added as necessary. The dry blended mixture can also be extruded and pelletized. For dry blending, it is preferable to use a mixer that can mix pellet-shaped raw materials, and more preferably a tumbler mixer. For extrusion, a known extruder such as a single-screw extruder, a twin-screw extruder, or a twin-screw single-screw extruder can be used.

[0110] The method for forming the intermediate layer is not particularly limited, but examples include a method in which the intermediate layer composition is first molded into a hemispherical half shell, two of which are used to encase the spherical core, and then pressure molded, or a method in which the intermediate layer composition is injection molded onto the spherical core to encase the spherical core.

[0111] When the intermediate layer is formed by injection molding the intermediate layer composition onto the spherical core, it is preferable to use upper and lower molds having hemispherical cavities. The intermediate layer can be formed by injection molding by protruding a hold pin, inserting and holding the spherical core, injecting the heated and molten intermediate layer composition, and cooling it to form the intermediate layer.

[0112] When the intermediate layer is molded by compression molding, the molding of the half shell can be performed by either compression molding or injection molding, but compression molding is preferred. Conditions for compression molding the intermediate layer composition into the half shell include, for example, a pressure of 1 MPa or more and 20 MPa or less, and a molding temperature of -20°C or more and +70°C or less relative to the flow start temperature of the intermediate layer composition. By using the above molding conditions, a half shell having a uniform thickness can be molded. For example, a method for molding the intermediate layer using the half shell includes a method of covering a spherical core with two half shells and compression molding. Conditions for compression molding the half shell into the intermediate layer include, for example, a molding pressure of 0.5 MPa or more and 25 MPa or less, and a molding temperature of -20°C or more and +70°C or less relative to the flow start temperature of the intermediate layer composition. By using the above molding conditions, a middle layer having a uniform thickness can be molded.

[0113] The molding temperature means the maximum temperature that the surface of the recess in the lower die reaches during the period from mold clamping to mold opening. The flow start temperature of the composition was measured by subjecting a pelletized thermoplastic resin composition to a plunger area of ​​1 cm using a Shimadzu Corporation "Flow Tester CFT-500". 2The measurement can be performed under the conditions of DIE LENGTH: 1 mm, DIE DIA: 1 mm, load: 588.399 N, starting temperature: 30° C., and heating rate: 3° C. / min.

[0114] The manner in which the cover is molded using the cover composition is not particularly limited, but examples thereof include a manner in which the cover composition is directly injection molded onto the intermediate layer, or a manner in which a hollow shell is molded from the cover composition, and a sphere on which the intermediate layer is formed is covered with a plurality of shells and compression molded (preferably, a method in which a hollow half shell is molded from the cover composition, and a sphere on which the intermediate layer is formed is covered with two half shells and compression molded). The golf ball body with the molded cover is removed from the mold, and is preferably subjected to surface treatment such as deburring, cleaning, and sandblasting as necessary. Also, a mark can be formed as desired.

[0115] In the present invention, for example, a hollow first shell having a first color and a hollow second shell having a second color are prepared, and a sphere having an intermediate layer is covered with a plurality of the first and second shells and compression molded to form the first and second regions on the surface of the golf ball. Also, a hollow half shell having a first color and a hollow half shell having a second color are molded, and a sphere having an intermediate layer is covered with these two half shells and compression molded to form a hemispherical first region having the first color and a hemispherical second region having the second color on the surface of the golf ball.

[0116] Dimples are preferably formed on the cover of the golf ball of the present invention. The total number of dimples formed on the cover is preferably 200 to 500. If the total number of dimples is less than 200, the effect of the dimples is difficult to obtain. If the total number of dimples exceeds 500, the size of each dimple becomes small, and the effect of the dimples is difficult to obtain. The shape (shape in plan view) of the dimples formed is not particularly limited, and the following may be used alone or in combination: circle; polygon such as approximately triangle, approximately square, approximately pentagon, approximately hexagon; or other irregular shape.

[0117] The golf ball with the molded cover is removed from the mold, and if necessary, is preferably subjected to surface treatment such as deburring, cleaning, sandblasting, etc. Furthermore, a coating film or marking can be formed as desired.

[0118] The coating film of the golf ball of the present invention can be formed by applying a paint to the surface of the golf ball body. The method for applying the paint is not particularly limited, and any known method can be used, such as spray coating or electrostatic coating.

[0119] When a first region having a first color or a second region having a second color is formed with a colored coating, the first region or the second region can be formed, for example, by applying paint to the desired shape of the first region or the second region.

[0120] When spray coating is performed using a two-component curing urethane coating as the coating, the polyisocyanate composition and the polyol composition may be supplied by respective pumps and continuously mixed in a line mixer arranged just before the air gun, and the resulting mixture may be spray coated, or the polyol and the polyisocyanate may be spray coated separately using an air spray system equipped with a mixing ratio control mechanism. The coating may be spray coated in one go, or may be overcoated multiple times.

[0121] 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.

[0122] [Golf ball structure] The structure of the golf ball of the present invention is not particularly limited as long as it has a core and a cover disposed on the outside of the core. In a preferred embodiment, the golf ball of the present invention has at least one intermediate layer between the core and the cover. Examples of the golf ball structure include a two-piece golf ball having a spherical core and a cover covering the spherical core, a three-piece golf ball having a spherical core, one intermediate layer covering the spherical core, and a cover covering the intermediate layer, and a multi-piece golf ball having a spherical core, two or more intermediate layers covering the spherical core, and a cover covering the intermediate layer.

[0123] When there are multiple intermediate layers, the color tone of the outermost intermediate layer is measured.

[0124] The core of the golf ball of the present invention is preferably spherical. The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, even more preferably 38.8 mm or more, and is preferably 42.2 mm or less, more preferably 41.8 mm or less, even more preferably 41.2 mm or less, and most preferably 40.8 mm or less. If the diameter of the spherical core is 34.8 mm or more, the thickness of the cover is not too thick, and the resilience is better. On the other hand, if the diameter of the spherical core is 42.2 mm or less, the cover is not too thin, and the function of the cover is more fully exhibited.

[0125] The thickness of the intermediate layer is preferably 0.8 mm or more, more preferably 0.9 mm or more, and even more preferably 1.0 mm or more, and is preferably 2.2 mm or less, more preferably 2.0 mm or less, and even more preferably 1.8 mm or less. If the thickness of the intermediate layer is 0.8 mm or more, molding of the intermediate layer becomes easier, and if it is 2.2 mm or less, the diameter of the core can be relatively large, improving the resilience performance of the golf ball. When there are multiple intermediate layers, it is preferable that the total thickness of the multiple intermediate layers is within the above range.

[0126] The cover of the golf ball of the present invention is preferably a single layer. The thickness of the cover is preferably 0.3 mm or more, more preferably 0.4 mm or more, even more preferably 0.5 mm or more, and is preferably 2.0 mm or less, more preferably 1.5 mm or less, even more preferably 1.0 mm or less. If the thickness of the cover is 0.3 mm or more, molding of the cover becomes easier, and if it is 2.0 mm or less, the diameter of the core can be relatively large, improving the resilience performance of the golf ball.

[0127] The thickness of the coating is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less, because if the coating is less than 5 μm, the coating is more likely to wear away with continued use, and if the coating is more than 50 μm, the effect of the dimples is reduced, resulting in a decrease in the flight performance of the golf ball.

[0128] The diameter of the golf ball of the present invention is preferably 40 mm to 45 mm. From the viewpoint of satisfying the standards of the United States Golf Association (USGA), the diameter is particularly preferably 42.67 mm or more. From the viewpoint of suppressing air resistance, the diameter is more preferably 44 mm or less, and particularly preferably 42.80 mm or less. In addition, the mass 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 more preferably 44 g or more, and particularly preferably 45.00 g or more. From the viewpoint of satisfying the standards of the USGA, the mass is particularly preferably 45.93 g or less.

[0129] 5 is a partially cutaway cross-sectional view showing a golf ball 1 according to one embodiment of the present invention. Golf ball 1 has a spherical core 2, an intermediate layer 3 that covers the spherical core, and a cover 4 that covers the intermediate layer. A large number of dimples 31 are formed on the surface of this cover. The portion of the surface of this golf ball other than the dimples 31 is land 32. This golf ball has a paint layer 5 on the outside of the cover. EXAMPLES

[0130] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0131] [Evaluation method] (1) Color tone The color tones of the intermediate layer and the surface of the golf ball were measured using a color difference meter ("CM-350d" manufactured by Konica Minolta, Inc.) The color tones of the golf ball were measured in a state in which a coating film was formed on the golf ball body. Measurement conditions Measurement wavelength range: 360nm~740nm Measurement area (diameter): 8mmφ Measurement time: 1 second

[0132] (2) Ease of finding in rough drafts Each golf ball was placed in the rough (grass length 5-10cm) and examined at 1m intervals from a distance of 1m to 10m from the subject, and the longest distance at which the ball's color combination could be correctly identified was calculated. Evaluations were conducted by 20 subjects, and the average distance was calculated.

[0133] (3) Discomfort when shooting Twenty subjects were asked to place the golf ball so that the boundary between the first hemispherical area and the second hemispherical area was visible, pick up the driver and address the ball, and the results were compiled to see if they felt any discomfort when taking the shot. ◎: 17 to 20 people answered that they felt no discomfort. ○: 13 to 16 people answered that they did not feel any discomfort. △: 9 to 12 people answered that they did not feel any discomfort. ×: Eight or fewer people answered that they did not feel uncomfortable.

[0134] [Manufacturing golf balls] (1) Core preparation The rubber composition shown in Table 1 was kneaded with a kneading roll and then hot-pressed at 170°C for 20 minutes in upper and lower molds having hemispherical cavities to obtain a spherical core with a diameter of 39.7 mm. The amount of barium sulfate was adjusted so that the mass of the resulting golf ball would be 45.3 g.

[0135] [Table 1]

[0136] The raw materials used in Table 1 are as follows: Polybutadiene rubber: JSR Corporation, high cis polybutadiene "BR730" (cis-1,4-bond content = 96 mass%, 1,2-vinyl bond content = 1.3 mass%, Mooney viscosity (ML 1+4 (100℃)=55, molecular weight distribution (Mw / Mn)=3) Zinc acrylate: Nisshoku Techno Fine Chemical Co., Ltd., "ZNDA-90S" Zinc oxide: "Ginrei R" manufactured by Toho Zinc Co., Ltd. Barium sulfate: Sakai Chemical Industry Co., Ltd., "Barium Sulfate BD" PBDS: Bis(pentabromodiphenyl) disulfide manufactured by Kawaguchi Chemical Industry Co., Ltd. Dicumyl peroxide: NOF Corporation, "Percumyl (registered trademark) D"

[0137] (2) Forming the middle layer The blending materials shown in Table 2 were mixed in a twin-screw kneading extruder to prepare a pellet-shaped intermediate layer resin composition. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D of 35, and the blend was heated to 160 to 230° C. at the die position of the extruder. The intermediate layer resin composition obtained was injection molded onto the spherical core obtained as described above to form an intermediate layer having a thickness of 1 mm.

[0138] [Table 2]

[0139] Himilan 1605: Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui Dow Polychemicals Himilan AM7329: Zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui Dow Polychemicals Titanium oxide: Ishihara Sangyo Kaisha "A220" FX305: Lemon Yellow, manufactured by Shinroihi GPX-17: Dayglo Saturn Yellow GPL-15: Day-Glo Blaze Orange

[0140] (3) Molding the cover The materials shown in Table 3 were dry blended and mixed in a twin-screw kneading extruder to obtain a pellet-shaped cover (half shell) composition. Extrusion was performed with a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D of 35. The compound was heated to 150 to 230°C at the die of the extruder.

[0141] The compression molding of the half shells was performed by putting the obtained pellet-like resin composition for the cover into each recess of the lower mold of the half shell molding die, one by one, and molding the half shells by applying pressure under the conditions of a molding temperature of 170°C, a molding time of 5 minutes, and a molding pressure of 2.94 MPa. The spherical core with the intermediate layer formed thereon was concentrically covered with two half shells A and B having different colors, and a cover was formed by compression molding. The compression molding was performed under the conditions of a molding temperature of 150°C, a molding time of 2 minutes, and a molding pressure of 9.8 MPa. The thickness of the cover was 0.5 mm.

[0142] [Table 3]

[0143] The raw materials used in Table 3 are as follows: Urethane resin: Elastollan (registered trademark) NY80A: manufactured by BASF Japan, polyurethane elastomer (polyol component: polytetramethylene ether glycol, polyisocyanate component: dicyclohexylmethane-4,4'-diisocyanate, chain extender: 1,4-butanediol) (Shore A hardness 80) JF-90: Johoku Chemical Industry Co., Ltd., light stabilizer Titanium oxide: Ishihara Sangyo Kaisha, Ltd., "A220" Epocolor FP3000: Manufactured by UKSEUNG CHEMICAL CO., LTD. (Fluorescent pigment made by dispersing and fixing fluorescent dye in benzoguanamine resin (condensation product of benzoguanamine and formaldehyde)) FX305: Lemon Yellow, manufactured by Shinroihi FX-327: Magenta, manufactured by Shinroihi GPX-17: Dayglo Saturn Yellow GPL-15: Day-Glo Blaze Orange ZQ-14: Dayglo (fluorescent pigment made by dispersing and fixing fluorescent dye in polyester resin) Fire Orange ZQ-17: Dayglo (fluorescent pigment made by dispersing and fixing fluorescent dye in polyester resin) Saturn Yellow ZQ-18: Dayglo (fluorescent pigment made by dispersing and fixing fluorescent dye in polyester resin) Signal Green FP113: UKSEUNG CHEMICAL CO., LTD. Red (RED) FP1050: UKSEUNG CHEMICAL CO., LTD. Blue (BLUE)

[0144] (4) Preparation of coating composition [Polyol composition No. 1 (urethane polyol)] Polytetramethylene ether glycol (PTMG, number average molecular weight 650) and trimethylolpropane (TMP) were dissolved in a mixed solvent (toluene / methyl ethyl ketone, mass ratio: 15 / 85). The molar ratio (PTMG:TMP) was 1.8:1.0. To this solution, 0.1 mass% of dibutyltin dilaurate was added as a catalyst based on the total amount of the base material. While maintaining this polyol solution at 80°C, isophorone diisocyanate (IPDI) was added dropwise and mixed. The molar ratio (NCO / OH) of this mixed solution was 0.6. After the dropwise addition, stirring was continued until the isocyanate component in the mixed solution disappeared, and then the mixture was cooled to room temperature to obtain polyol composition No. 1 containing urethane polyol as the base material. The solid content of the polyol composition No. 1 was 30 mass%, the content of PTMG was 67 mass%, the hydroxyl value of the solid content was 67.4 mgKOH / g, and the weight average molecular weight of the urethane polyol was 4867. When a filler was blended, it was added to the polyol composition. The blending amount was 45 parts by mass with respect to 100 parts by mass of the polyol composition constituting the coating film.

[0145] [Polyisocyanate composition No. 1] 30 parts by mass of an isocyanurate modified hexamethylene diisocyanate (trade name "Duranate TKA-100" of Asahi Kasei Chemicals Corporation, NCO content: 21.7% by mass), 30 parts by mass of a biuret modified hexamethylene diisocyanate (trade name "Duranate 21S-75E" of Asahi Kasei Chemicals Corporation, NCO content: 15.5% by mass), and 40 parts by mass of an isocyanurate modified isophorone diisocyanate (trade name "Desmodur Z4470" of BAYER, NCO content: 11.9% by mass) were mixed. Methyl ethyl ketone, n-butyl acetate, and toluene were added as solvents to this mixture and mixed to obtain polyisocyanate composition No. 1 as a curing agent. The concentration of the polyisocyanate component in this composition was 60% by mass.

[0146] A coating composition was prepared by mixing the polyol composition and the polyisocyanate composition in the compounding ratio shown in Table 4. The surface of the golf ball body obtained above was sandblasted and marked, and then coating was applied with a spray gun and the coating was dried in an oven at 40°C for 24 hours to obtain a golf ball having a diameter of 42.7 mm and a mass of 45.3 g.

[0147] [Table 4]

[0148] Silica: Evonik CARPLEX FPS-1 (wet silica, volume average particle size: 7.0 μm)

[0149] The coating was performed by placing the golf ball body on a rotor equipped with prongs, rotating the rotor at 300 rpm, and moving the air gun vertically at a spray distance (7 cm) from the golf ball body. The interval between each recoat was 1.0 second. The spray conditions for the air gun were as follows: recoat; 2 times, spray air pressure; 0.15 MPa, pressure tank air pressure; 0.10 MPa, application time per coat; 1 second, ambient temperature; 20°C to 27°C, ambient humidity; 65% or less. The evaluation results of the obtained golf balls are also shown in Table 5.

[0150] [Table 5]

[0151] From Table 5, a golf ball having a core and a cover disposed on the outside of the core, the surface of the golf ball having a first region of a first color and a second region of a second color, the hue of the first color is H1 expressed using an H value in the HSL color space, and the hue of the second color is H2 expressed using an H value in the HSL color space, and the golf ball in which H1 and H2 satisfy a specific relationship has high visibility and causes little discomfort when shots are made. [Explanation of symbols]

[0152] 1: Golf ball, 2: Spherical core, 3: Intermediate layer, 4: Cover, 5: Coating, 31: Dimples, 32: Land

Claims

1. A golf ball having a core, a translucent cover disposed on the outside of the core, at least one intermediate layer between the core and the translucent cover, and a coating film covering the translucent cover, the surface of the golf ball has a hemispherical first region of a first color and a hemispherical second region of a second color; the hue of the first color is H1 expressed using an H value in the HSL color space; the hue of the second color is H2 expressed using an H value in the HSL color space; The golf ball is characterized in that H1 and H2 satisfy the following formula (1). 46≦|H1-H2|≦60 (1)

2. 2. The golf ball according to claim 1, wherein the hue of the outermost layer of the intermediate layer is H0 expressed using an H value in the HSL color space, and one of |H0-H1| and |H0-H2| is less than 10 and the other is 10 or greater.

3. A golf ball having a core, a cover disposed on the outside of the core, at least one intermediate layer between the core and the cover, and a coating film covering the cover, the surface of the golf ball has a hemispherical first region of a first color and a hemispherical second region of a second color; the hue of the first color is H1 expressed using an H value in the HSL color space; the hue of the second color is H2 expressed using an H value in the HSL color space; The H1 and H2 satisfy the following formula (1), 46≦|H1-H2|≦60 (1) The hue of the outermost layer of the intermediate layer is H0 expressed using an H value in the HSL color space, and one of |H0-H1| and |H0-H2| is less than 10 and the other is 10 or greater.

4. the saturation of the first color in the first region is S1, which is expressed as an S value in the HSL color space; the luminance of the first color of the first region is L1, which is represented by an L value in the HSL color space; 4. The golf ball according to claim 1, wherein S1 is 40 or greater and 100 or less, and L1 is 30 or greater and 100 or less.

5. the saturation of the second color in the second region is S2, which is expressed as an S value in the HSL color space; the luminance of the second color of the second region is L2, which is represented by an L value in the HSL color space; 5. The golf ball according to claim 1, wherein S2 is 40 or greater and 100 or less, and L2 is 30 or greater and 100 or less.

6. 6. The golf ball according to claim 1, wherein the coating contains a resin component and a filler.

7. 6. The golf ball according to claim 1, wherein the coating is a clear coating.

8. 8. The golf ball according to claim 1, wherein the first region and the second region are each formed by a colored cover.

9. 8. The golf ball according to claim 1, wherein the first region and the second region are each formed by a colored coating.

10. 8. The golf ball according to claim 1, wherein one of the first region and the second region is formed by a colored cover, and the other of the first region and the second region is formed by a colored coating.

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