US20120035002A1

US20120035002A1 - Colored golf ball

Info

Publication number: US20120035002A1
Application number: US13/078,287
Authority: US
Inventors: Kae Iizuka; Eiji Takehana
Original assignee: Bridgestone Sports Co Ltd
Current assignee: Bridgestone Sports Co Ltd
Priority date: 2010-08-05
Filing date: 2011-04-01
Publication date: 2012-02-09
Also published as: JP2012034776A; JP5521872B2

Abstract

In a colored golf ball having a core, a cover of at least one layer encasing the core and a coat of paint applied to a surface of an outermost layer of the cover, the outermost cover layer is formed of a resin composition which includes (a) a thermoplastic resin, (b) a color pigment or dye, (c) titanium oxide, and (d) a lubricant. The resin composition has a total light transmittance of at least 1.0 but not more than 40, and a diffuse transmittance of at least 1.0 but not more than 40. The paint coat contains a polarizing pigment. The ball has an excellent visibility and stylishness and, in spite of being pastel-colored, is endowed with an appearance that is lustrous and elegant.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2010-176316 filed in Japan on Aug. 5, 2010, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a colored golf ball.
2. Prior Art
Not all golf balls lately are white; a variety of colored balls have appeared on the market in response to golfer's preferences. In particular, highly stylish colored golf balls and colored golf balls having an elegant feel are being developed to suit the tastes of women golfers.
Colored balls with an elegant appearance that are currently sold on the market include balls having a fluorescent outermost layer coated on the surface with paint containing a polarizing pigment. Pastel colored golf balls have also been around for some time. However, pastel balls contain a large amount of titanium oxide in the material forming the outermost layer, and thus often end up having a non-transparent (matte) shade of color. Even when a metal oxide-containing paint is applied to the outermost layer of such a ball, this does not produce a shade of color having a lustrous, transparent feel, and so an elegant appearance is not achieved.
Examples of prior art relating to colored golf balls include JP-A 2000-254250, JP-A 2004-033594, JP-A 2007-144097 and JP-A 2009-45347 (and the corresponding U.S. Pat. Application 20090054176). However, none of these provide pastel colored golf balls having a lustrous and elegant feel.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a colored golf ball which has excellent visibility and stylishness and moreover which, although having a pastel tone, is endowed with a lustrous and elegant appearance.
The inventors have discovered that, by forming the outermost layer of the cover of a golf ball from a resin composition having a specific total light transmittance and a specific diffuse transmittance, and additionally coating thereon a polarizing pigment-containing paint so as to form a paint coat, it is possible to achieve a color tone which, although in a pastel shade, is lustrous and has a sense of transparency, thus giving a colored golf ball endowed with outstanding visibility and stylishness and an elegant feel.
Accordingly, the present invention provides a colored golf ball composed of a core, a cover of at least one layer encasing the core, and a coat of paint applied to a surface of an outermost layer of the cover. The outermost cover layer is formed of a resin composition which includes (a) a thermoplastic resin, (b) a color pigment or dye, (c) titanium oxide, and (d) a lubricant. The resin composition has a total light transmittance of at least 1.0 but not more than 40, and a diffuse transmittance of at least 1.0 but not more than 40. The paint coat contains a polarizing pigment.
The color pigment or dye (b) is preferably selected from the group consisting of red pigments, blue pigments, yellow pigments, green pigments, purple pigments and black pigments.
The resin composition is preferably formulated as follows: (a) from 90 to 99 wt % of a thermoplastic resin, (b) from 0.003 to 2 wt % of a color pigment or dye, (c) from 0.01 to 2.5 wt % of titanium oxide, and (d) from 0.1 to 5.5 wt % of a lubricant.
It is preferable for the ball to have a surface with a color tone which, expressed numerically in the L*a*b* color space according to JIS Z8729, is: L*=50 to 95, a*=−20 to 30, and b*=−45 to 45.
Preferably, the paint coat includes 100 parts by weight of a base resin, from 0.05 to 1 part by weight of a fluorescent whitener and from 0.1 to 3 parts by weight of a polarizing pigment per 100 parts by weight of a base resin, and the fluorescent whitener and polarizing pigment have a weight ratio therebetween of from 0.05 to 5.0.
The golf ball of the invention has a color tone with a luster and sense of transparency not previously achieved in pastel golf balls, and is thus endowed with outstanding visibility and stylishness and an elegant feel.

BRIEF DESCRIPTION OF THE DIAGRAM

FIG. 1 is a schematic cross-sectional view of a golf ball according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The objects, features and advantages of the invention will become more apparent from the following detailed description, taken in conjunction with the foregoing diagram.
In the colored golf ball of the invention, the outermost layer of the cover is formed of a resin composition having a total light transmittance and a diffuse transmittance within specific ranges, and has thereon a paint coat formed by the application of a polarizing pigment-containing paint.
The construction of the inventive golf ball, so long as it has a core and a cover of at least one layer, the cover having an outermost layer with a paint coat on the surface thereof, may be suitably selected within a range that does not depart from the objects of the invention. For example, in the case of three-piece solid golf ball having a two-layer cover composed of an inner cover layer (intermediate layer) and an outer cover layer (outermost layer), as shown in FIG. 1, the golf ball G may be one having a three-piece construction composed of at least a core 1, an inner cover layer (intermediate layer) 2 encasing the core 1, and an outer cover layer 3 encasing the inner cover layer 2, and having also thereon a coat of paint 4. In cases where the ball has a cover with a multilayer construction of two or more layers, the cover layers are sometimes referred to collectively herein as the “cover.” That is, in the case of the three-piece solid golf ball shown in FIG. 1, the intermediate layer 2 and the outer cover layer 3 are sometimes referred to collectively as the “cover.” In such a case, a plurality of dimples D are generally formed on the surface of the outer cover layer 3, which is the outermost layer of the ball. Although FIG. 1 shows an arrangement in which a core 1, an intermediate layer 2 and an outer cover layer 3 are formed as a three-layer construction, as noted above, this arrangement may be suitably varied within a range that does not depart from the objects of the invention. For example, if necessary, use may be made of an arrangement wherein the cover is composed of only one layer—the outer cover layer 3, or an arrangement wherein the cover has three or more layers, including at least two intermediate layers 2. It is also possible to form the core 1 as a plurality of layers. The colored golf ball is described in detail below while referring to FIG. 1.
The core 1 may be obtained by vulcanizing a rubber composition prepared by blending a known rubber material such as cis-1,4-polybutadiene as the base together with a co-crosslinking agent (e.g., an unsaturated carboxylic acid, or a metal salt thereof), an inorganic filler (e.g., zinc oxide, barium sulfate) and an organic peroxide (e.g., dicumyl peroxide, 1,1-bis(t-butylperoxy)cyclohexane). In the present invention, no particular limitation is imposed on the core diameter. Nor is any particular limitation imposed on the color of the core.
The intermediate layer 2 may be formed primarily of a resin material which is any of various thermoplastic resins or thermoplastic elastomers, such as known ionomeric resins and polyurethanes. This intermediate layer 2, as mentioned above, may be formed as two or more layers using similar or dissimilar materials, depending on the ball specifications and the like. The method of molding the intermediate layer 2 is not subject to any particular limitation; a known method such as injection molding may be suitably selected for this purpose. The thickness of the intermediate layer 2 is not subject to any particular limitation, provided it is suitable for the ball specifications and the like. In cases where the cover encasing the core 1 is a single layer, an intermediate layer 2 is not formed, the cover being formed over the core 1 from the subsequently described outermost layer-forming resin composition.
The outer cover layer 3 is formed of a resin composition which includes as the essential ingredients: (a) a thermoplastic resin, (b) a color pigment or dye, (c) titanium oxide, and (d) a lubricant. The respective ingredients of this outer cover layer (outermost layer)-forming material are described in detail below.

(a) Thermoplastic Resin

The thermoplastic resin serving as component (a) is the primary component in the outer cover layer-forming material. Various known thermoplastic resins may be used without particular limitation. Specifically, preferred use may be made of olefinic thermoplastic resins and thermoplastic polyurethanes. Of these, the use of nonionic resins such as olefin-unsaturated carboxylic acid copolymers and olefin-unsaturated carboxylic acid-carboxylic acid ester copolymers, or of ionic resins or thermoplastic polyurethanes is especially preferred. These may be used singly or as combinations of two or more thereof.
When two or more of the above resins are used together, although not subject to any particular limitation, it is preferable to use an ionic resin and/or a nonionic resin in combination with a thermoplastic polyurethane. In such a case, the relative proportions by weight of the ionic resin and/or nonionic resin (when used together, the combined amount of both) and the thermoplastic polyurethane, while not subject to any particular limitation, is preferably from 100:0.1 to 100:10, and more preferably from 100:0.5 to 100:5. By setting the relative proportions of both in the above range, a cover having a suitable light transmittance can be formed, in addition to which coloration having depth is possible, enabling the elegant feel of the golf ball as a whole to be increased.
Use can be made of known ionic resins and nonionic resins without particular limitation. Illustrative examples of ionic resins that may be used include those available under the trade names HIMILAN 1601, HIMILAN 1605, HIMILAN 1557 and HIMILAN 1855 (all products of DuPont-Mitsui Polychemicals), and those available under the trade names IOTEK 8030 and IOTEL 7010 (ExxonMobil). Illustrative examples of nonionic resins that may be used include that available under the trade name NUCREL N035C (DuPont-Mitsui Polychemicals).
Use may likewise be made of known thermoplastic polyurethanes without particular limitation. Illustrative examples include those available under the trade names PANDEX T8295 and PANDEX T8260 (DIC Bayer Polymer).
The proportion in which component (a) is included may be set to from 90 to 99 wt %, and preferably from 93 to 99 wt %. Outside of the above range, the ball may have a poor scuff resistance and durability.

(b) Color Pigment or Dye

The color pigment or dye serving as component (b) is included for the purpose of adjusting the perceived color of the ball. In the practice of the invention, a known pigment or dye may be used. From the standpoint of discoloration resistance, the use of a pigment is preferred. Exemplary pigments include red pigments, blue pigments, yellow pigments, green pigments, violet pigments and black pigments. More specifically, examples of red pigment include quinacridone pigments, examples of blue pigments include phthalocyanine pigments, examples of yellow pigments include complex oxide pigments, examples of violet pigments include ultramarine violet, cobalt violet, manganese violet, dioxane violet and quinacridone violet; and examples of black pigments include carbon black. By including these, it is possible to express pastel colors having depth. These pigments may be used singly or as combinations of two or more thereof; the combinations or included amounts of these pigments may be suitably selected according to the ball specifications and the like. Commercial products may be used as the above pigments. Specific examples of such commercial products include those available under the trade names CHROMOFINE (Dainichi Seika Color & Chemicals Mfg. Co., Ltd.), TIPAQUE YELLOW (Ishihara Sangyo Kaisha, Ltd.) and TOKABLACK (Tokai Carbon Co., Ltd.). The proportion in which component (b) is included may be set to from 0.003 to 2 wt %, and more preferably from 0.005 to 1.5 wt %. When the amount of component (b) added is too low, coloration may be poor. When too much is added, coloration may be excessive, resulting in the loss of a pastel feel.

(c) Titanium Oxide

The titanium oxide serving as component (c) is included for the purpose of enhancing the ability to hide the outermost layer-forming resin composition. In the practice of this invention, by adjusting the amount in which the titanium oxide is included, the extent to which the underlying layer shows through can be changed, in addition to which the degree of coloration can be varied. In this invention, a known titanium oxide may be used. For example, preferred use may be made of products commercially available under the trade name TIPAQUE (Ishihara Sangyo Kaisha). This titanium oxide may also be used as a white pigment, enabling depth to be imparted to the perceived color of the ball. The proportion in which component (c) is included may be set to from 0.01 to 2.5 wt %, and more preferably from 0.05 to 2 wt %. If the amount of component (c) added is too low, the hiding power may be inadequate, allowing the underlying color to affect ball coloration. On the other hand, the addition of too much component (c) may increase the sense of opacity, resulting in a loss of the elegant feel.

(d) Lubricant

The lubricant serving as component (d) is an ingredient which functions as, for example, a processing aid, a slip enhancer and a dispersant. Exemplary lubricants include organic acids such as fatty acids, fatty acid metal salts and fatty amides, as well as acrylic polymers and silicones. The proportion in which component (d) is included may be set to from 0.1 to 5.5 wt %, and preferably from 1 to 3 wt %. If the amount of component (d) is too small, the composition may not have good flow properties, which may make molding impossible to carry out. On the other hand, if too much component (d) is added, the lubricant may bleed out, possibly marring the appearance of the ball surface or resulting in poor adhesion with the paint coat 4 or the underlying layer (the intermediate layer 2 or the core 1).

(e) Additives

In addition to above components (a) to (d), it is possible to include also various types of additives as component (e). Additives for various resin applications may be used, such as antioxidants, ultraviolet absorbers, flow enhancers and thickeners. The amount in which these additives are added is not subject to any particular limitation and may be suitably selected within a range that does not adversely affect the moldability and other properties of the resin composition. Typically, the amount of use per 100 wt % of above component (a) may be set to from 0.05 to 5 wt %, and preferably from 0.1 to 4 wt %.
The outer cover layer 3 formed using the resin composition formulated from the above components may be set to a thickness of from 0.3 to 2.1 mm, and preferably from 0.5 to 1.7 mm. If the thickness of the outer cover layer 3 is too small, the underlying material may show through, detracting from the ball coloration. On the other hand, if the thickness is too large, uniform injection molding may be difficult to carry out, resulting in a loss in the sense of ball quality.
The outer cover layer-forming material has a haze value of at least 80 but not more than 100, and preferably at least 90 but not more than 100. If the haze value is too low, the balance between the sense of transparency and the pastel feel may worsen, possibly detracting from the sense of elegance of the ball's appearance. The total light transmittance is at least 1.0 but not more than 40, and preferably at least 1.0 but not more than 30. If the total light transmittance is too large, the transparency may be excessive, as a result of which pastel-toned colors may not be achieved. Also, the diffusion transmittance is at least 1.0 but not more than 40, and preferably at least 1.0 but not more than 30. If the diffusion transmittance is too large, the transparency may be excessive, as a result of which pastel-toned colors may not be achieved.
As used herein, “total light transmittance” and “diffuse transmittance” refer respectively to the degree of light transmission and the degree of light diffusion when light from a light source is applied through a plastic (outer cover layer material) test specimen, these being values obtained in accordance with JIS K7105 (1981).
“Haze” refers to a value computed by the following formula from the above total light transmittance and diffuse transmittance. Reference should be made to JIS K7136 (2000) for further details.
Haze(%)=(diffusion transmittance T _d)/(total light transmittance T _t)×100
In the above description, a larger total light transmittance value indicates that light passes through more easily and the degree of transparency is higher; conversely, a smaller value indicates that light passes through with greater difficulty and the degree of transparency is lower. In the case of both the diffuse transmittance and the Haze value, smaller values indicate a greater degree of clouding; conversely, larger values indicate less light diffusion and a high degree of transparency.
Preparation of the above-described material may be carried out using a known mixing apparatus, such as a single-screw extruder or a twin-screw extruder. In this invention, the use of a twin-screw extruder is preferred. Alternatively, these extruders may be used in a tandem arrangement, such as single-screw extruder/twin-screw extruder or twin-screw extruder/twin-screw extruder. These extruders need not be of a special design; the use of existing extruders will suffice. The method of molding the cover using the above material is not subject to any particular limitation. For example, use may be made of an injection molding process or a compression molding process. In cases where an injection molding process is used, the process may one in which a prefabricated core is placed at a predetermined position in an injection mold, following which the above material is introduced into the mold. Alternatively, in cases where a compression molding process is used, the process may be one in which a pair of half-cups is produced of the above material, the cups are placed over a core, and heat and pressure are applied within a mold. When molding is carried out under applied heat and pressure, the molding conditions employed may be a temperature of from 120 to 170° C. and a molding time of from 1 to 5 minutes.
As shown in FIG. 1, the surface of the outer cover layer 3 is covered with a coat of paint 4. The thickness of this paint coat 4, although not subject to any particular limitation, is preferably at least 5 and more preferably at least 10 μm, but preferably not more than 20 μm, and more preferably not more than 16 μm. If the paint coat 4 is too thin, the durability of the coat may be inadequate. On the other hand, if the paint coat 4 is too thick, this may lower the rebound of the ball and may lead to peeling of the paint.
This paint coat 4 is formed by applying a paint composed of a base resin such as polyurethane, to which a polarizing pigment and various solvents and additives have been suitably added. The paint coat has a sense of transparency due to synergistic effects with the perceived color of the outer cover layer 3, thereby enabling a pastel-toned color that is lustrous and has an elegant feel to be obtained.
The base resin of the paint is not subject to any particular limitation. For example, use may be made of a known urethane resin. However, in this invention, the use of a two-component curing urethane paint composed of a polyol component having hydroxyl groups and a polyisocyanate component having isocyanate groups is preferred. Examples of polyols that may be primarily used include urethanes, polyesters and acrylic resins, although other resins, such as epoxy resins, may be employed if necessary. Examples of polyisocyanates that may be used include tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, naphthalene diisocyanate, 1,4-phenylene diisocyanate, xylylene diisocyanate and hydrogenated xylylene diisocyanate, either singly or in modified forms as combinations thereof. The polyisocyanate component may generally take the form of an adduct, a biuret or an isocyanurate.
The polarizing pigment is included so as to enhance the elegant feel and sense of quality of the golf ball. For example, metal powder pigments, glass flakes, mica and pearlescent pigments may be included. In the present invention, the use of a pearlescent pigment is especially preferred. Any of the following may be used as the pearlescent pigment: metal oxide-coated mica, basic lead carbonate, bismuth oxychloride, and natural pearl essence. Of these, the selection of a metal oxide-coated mica is preferred because such pigments are nontoxic and have the best chemical stability. In such a metal oxide-coated mica, titanium dioxide or iron oxide is typically used as the metal oxide which coats the mica; by varying the coverage (thickness of the coating layer), various perceived colors and interference effects can be achieved. The particle size of the polarizing pigment is not subject to any particular limitation. However, because the pigment has a greater tendency to settle at a larger particle size, it is desirable to select a pigment having a suitable particle size. A commercial product may be used as the above polarizing pigment. Examples of such products are those available under the trade name XIRALLIC (Merck Japan).
The amount of polarizing pigment included per 100 parts by weight of the base resin may be set in a range of from 0.1 to 3 parts by weight, and preferably from 0.2 to 2 parts by weight. If the amount of polarizing pigment is too low, a suitable luminosity and brightness will be lost, as a result of which an elegant feel may not be achieved. On the other hand, including too much polarizing pigment may make the painting operation more difficult or may become a major cause in peeling of the paint coat.
In addition, to increase the luminosity of the paint, it is preferable to include a fluorescent whitener. The amount of fluorescent whitener included per 100 parts by weight of the base resin may be set to from 0.05 to 1 part by weight, and is more preferably used in such a way that the relative proportions of fluorescent whitener to polarizing pigment (fluorescent whitener/polarizing pigment), expressed as a weight ratio, are from 0.05 to 5.0.
Any known method used in the art may be employed as the method for applying the paint. For example, the entire ball may be spray-painted while perched on the tips of needles on a needle bed. Alternatively, prior to painting, to improve adhesion between the object to be painted (a sphere covered by the outer cover layer 3) and the paint coat 4, although not subject to any particular limitation, surface modification by plasma treatment or corona discharge treatment may be carried out, or a primer or the like may be applied.
The color of the outer cover layer-forming resin composition and the color of the colored golf ball after the coat of paint 4 has been formed on the surface of the outer cover layer 3 (i.e., after painting) may be suitably set according to the ball specifications and the like, and are not subject to any particular limitation. However, in this invention, it is preferable to set the color as follows in the L*a*b* color space according to JIS 28729.
First, with regard to the L*, a* and b* values of the outer cover layer-forming composition, the L* value is from 65 to 95, and preferably from 70 to 90; the a* value is from −15 to 15, and preferably from −12 to 12; and the b* value is from −35 to 30, preferably from −25 to 30, and more preferably from −18 to 28. When the color of this composition falls outside of the above ranges, the perceived color that is desired may not be attainable. For example, in cases where the L* value is smaller than the above range, the darkness increases, as a result of which a pastel feel may be lost.
Next, with regard to the L*, a* and b* values of the colored golf ball after it has been painted, the L* value is from 50 to 95, and preferably from 60 to 90; the a* value is from −20 to 30, and preferably from −15 to 15; and the b* value is from −45 to 45, and preferably from −35 to 30. Moreover, the saturation C, expressed as (a*²+b*²)^0.5, may be set to from 5 to 50, and preferably from 10 to 40. When the ball color falls outside of the above range, the perceived color that is desired may not be attainable. For example, in cases where the L* value is smaller than the above range, the darkness increases, as a result of which a sense of elegance may be lost.
Moreover, although not subject to any particular limitation, it is desirable for the L* value of the colored golf ball to be smaller than the L* value of the intermediate layer 2. When the L* value of the intermediate layer 2 is smaller than the L* value of the ball, the color of the intermediate layer 2 becomes relatively dark, which may influence the overlying outermost layer (outer cover layer 3) lying thereabove. In addition, although not subject to any particular limitation, it is recommended that the L* value difference between the intermediate layer 2 and the outer cover layer 3 be set to preferably from 1 to 30, and more preferably from 1 to 25. If this difference is too small, a sense of transparency may be lost. On the other hand, if it is too large, a pastel feel may be lost.
The golf ball of the invention, which can be manufactured so as to conform with the Rules of Golf for competitive play, may be produced to a ball diameter which is not less than 42.67 mm and to a weight which is not more than 45.93 g.

EXAMPLES

The following Examples are provided to illustrate the invention, and are not intended to limit the scope thereof.

Examples 1 to 4

Comparative Examples 1 to 4

A rubber composition having a common formulation for each example of the invention and each comparative example was prepared, masticated in a kneader or roll mill, then fashioned into a core under specific vulcanization conditions. Next, in each example, the intermediate layer-forming material shown in Table 1 and the outer cover layer-forming material shown in Table 2 were successively injection-molded over the resulting core to form a ball. A two-component curing urethane paint of the following formulation was then spray-painted onto the surface of the ball and dried, thereby producing colored golf balls in the respective examples of the invention and comparative examples. The numbers in the resin mixing material formulations shown in Tables 1 and 2 indicate parts by weight.

Rubber Formulation


Polybutadiene rubber	100	parts by weight
Zinc acrylate	29	parts by weight
Peroxide	1.2	parts by weight
Antioxidant	0.1	part by weight
Zinc oxide	26.7	parts by weight
Zinc salt of pentachlorothiophenol	0.2	part by weight
Red pigment	0.08	part by weight

Vulcanization of the above rubber was carried out at 155° C. for 15 minutes. The peroxide was a mixture of 1,1-di(t-butylperoxy)cyclohexane and silica that is available under the trade name PERHEXA C-40 (NOF Corporation). The antioxidant was NOCRAC NS-6 (Ouchi Shinko Chemical Industry Co., Ltd.).

TABLE 1

Intermediate layer-forming
material	a	b

Ionomers	SURLYN 6320 (trade name)	60	60
	NUCREL 035C (trade name)	40	40
Fatty acid	Magnesium stearate	69	69
Cation	Magnesium oxide	0.8	0.8
Colorants	Titanium oxide	4.1
	Magnesium stearate	1.0
	Yellow pigment		0.02

The materials mentioned in the table are described below.

SURLYN 6320: A magnesium-neutralized ethylene-methacrylic acid-acrylic acid ester copolymer available from E.I. DuPont de Nemours & Co.
NUCREL 035C: An ethylene-methacrylic acid-acrylic acid ester copolymer available from DuPont-Mitsui Polychemicals Co., Ltd.
Magnesium stearate: Available from Dainichi Kagaku under the trade name M-5GN.
Magnesium oxide: Magnesium oxide available from Kyowa Chemical Industry.
Titanium oxide: Available from Ishihara Sangyo Kaisha under the trade name TIPAQUE R550.

Paint Formulation


	Base resin	98.5 wt %
	Polarizing pigment	1.0 wt %
	Fluorescent whitener	0.5 wt %

Details of the above materials are provided below.

Base resin: two-component curing urethane paint
Polarizing pigment: Available from Merck under the trade name IRIODIN.

The appearance-related properties of the covers and golf balls obtained as described above in the respective examples of the invention and comparative examples were rated according to the following criteria. The results are shown in Table 2.

Total Light Transmittance and Diffusion Transmittance

Measurement was carried out under the following conditions using a light transmittance measuring instrument (Turbidimeter NDH5000W, manufactured by Nippon Denshoku Industries Co., Ltd.). The total light transmittance and diffuse transmittance were determined in accordance with JIS K7105, and the Haze value was determined in accordance with JIS K7136.

- Measurement conditions: Light source, D65; measurement method, 3
- Number of measurements: n=3 for each sample

The total light transmittance and the diffuse transmittance were obtained by directing the light source at a test specimen, measuring how much of the light passed through and how much diffused through the test specimen, and converting the results to numerical values. Larger values indicate a higher degree of transparency, and smaller values indicate a lower degree of transparency. Normally, when these measurements are carried out on a resin composition containing titanium oxide, the values obtained are substantially 0.

Ball Color

The color tone of the ball after topcoating was measured using a color difference meter (model SC-P, manufactured by Suga Test Instruments Co., Ltd.) and with a C light source having a 2° field, in accordance with JIS Z 8722-1994, Condition c (Measurement of Reflection (diffused illumination, 8° viewing angle (d/8: excluding specularly reflected component)), and was converted to a numerical value based on JIS Z8729-1994 (L*A*B* color system). A measurement area diameter of 30 mm was used.

Weatherability

Each type of ball (n=3) was exposed to sunlight together with an index ball. AE was measured at fixed intervals with a Lab color difference meter. When the ΔE of the index ball became 15 or more, exposure to sunlight was stopped, and the ΔE for each ball at that time was measured. The weatherability was rated according to the following ΔE criteria.

- Excellent: less than 5
- Good: 5 or more, but less than 13
- Fair: 13 or more

Elegant Feel

Sensory evaluations based on the following criteria were carried out by ten skilled golfers.

- Excellent: Eight or more of the ten golfers thought the ball had an elegant feel.
- Good: Five to seven of the ten golfers thought the ball had an elegant feel.
- Fair: Three or four of the ten golfers thought the ball had an elegant feel.
- NG: Two or less of the ten golfers thought the ball had an elegant feel.

Pastel Feel

- Excellent: Eight or more of the ten golfers thought the ball had a “pastel feel” (left an impression of a soft, intermediate color).
- Good: Five to seven of the ten golfers thought the ball had a “pastel feel” (left an impression of a soft, intermediate color).
- Fair: Three or four of the ten golfers thought the ball had a “pastel feel” (left an impression of a soft, intermediate color).
- NG: Two or less of the ten golfers thought the ball had a “pastel feel” (left an impression of a soft, intermediate color).

Transparent Feel

- Excellent: Eight or more of the ten golfers thought the ball had a “transparent feel” (left an impression of color depth and solidity).
- Good: Five to seven of the ten golfers thought the ball had a “transparent feel” (left an impression of color depth and solidity).
- Fair: Three or four of the ten golfers thought the ball had a “transparent feel” (left an impression of color depth and solidity).
- NG: Two or less of the ten golfers thought the ball had a “transparent feel” (left an impression of color depth and solidity).

	TABLE 2

	Example	Comparative Example

	1	2	3	4	1	2	3	4

Outermost

Color

yellow

purple

yellow

pink

blue

yellow

layer	Pigment/dye	titanium	quinacridone red	cyclic	anthra-	ultra-	titanium
formulation		yellow	(0.8)	dye	quinone	marine	yellow
			ultramarine		dye
			(0.35)
	Amount of	0.9	1.15	1.5	0.8	0.15	0.9
	pigment/dye

Himilan 1855	50	50	50
Himilan 1555	50	50	50
Thermoplastic	1	1	1
polyurethane

Titanium	1.8	1.8	1.0	1.0	0	1.5	0	1.8
oxide
Lubricant	1.5	1.5	1.5	1.5	1.5	1.5	1.5	1.5

Intermediate	Material	b	b	a
layer	L* value	98.5	98.5	65.0

Outermost	Haze	98.47	98.41	98.54	98.4	96.27	96.41	81.09	98.47
layer	Total light	8.3	1.99	8.32	1.7	82.02	49.55	47.77	8.3
composition	transmittance
properties	Diffuse	8.17	1.96	8.2	1.67	78.96	47.77	38.74	8.17
	transmittance
Color tone	L*	78.17	78.48	89.23	90.14	93.4	67.7	64.9	55.4
of ball	a*	7.37	8.75	−9.89	−9.41	−23.8	47.7	−12	3.3
	b*	−12.43	−13.29	25.03	25.4	90.9	7	−36.8	−22.9
	Saturation	14.5	15.9	26.9	27.1	7.7	12.2	11.3	23.6

L* value difference	−20.3	−20.0	−9.3	−8.4	−5.1	−30.8	−33.6	−9.6
between outermost layer
and intermediate layer

Ball	Weatherability	Exc.	Exc.	Exc.	Exc.	Fair	Good	Exc.	Fair
appearance	Elegant feel	Exc.	Good	Exc.	Good	Exc.	Fair	Fair	Fair
	Pastel feel	Exc.	Exc.	Exc.	Exc.	NG	NG	Fair	NG
	Transparent	Exc.	Exc.	Exc.	Exc.	Good	Good	Fair	Exc.
	feel

The materials mentioned in the table are described below.

- Titanium yellow: Pigment Yellow 53 (CAS No. 8007-18-19)
- Quinacridone Red: Pigment Red 202 (CAS No. 3089-17-6)
- Ultramarine: Pigment Blue 29 (CAS No. 57455-37-5)
- Cyclic dye: 2-Octadecyl-1-thioxane (CAS No. 27870-92-4)
- Anthraquinone dye: Pigment Red 263
- Himilan 1855: Zinc-neutralized ethylene-methacrylic acid-acrylic acid ester copolymer available from DuPont-Mitsui Polychemicals Co., Ltd.
- Himilan 1555: Sodium-neutralized ethylene-methacrylic acid copolymer available from DuPont-Mitsui Polychemicals Co., Ltd.
- Thermoplastic polyurethane:
  - Available from DIC Bayer Polymer under the trade name PANDEX T-R3080
- Titanium oxide: Available from Ishihara Sangyo Kaisha
- Lubricant: Magnesium stearate available from NOF Corporation

From the results in Tables 1 and 2, the respective comparative examples were inferior in the following ways to the examples of the invention.
In Comparative Example 1, compared with Examples 1 and 2 of the invention, the pigment or dye was yellow, but titanium oxide was not included; the total light transmittance and the diffuse transmittance were high. In addition, the a* and b* values for the ball were high. For this reason, the ball left an impression of elegance and transparency, but lacked a pastel feel
In Comparative Example 2, compared with Examples 3 and 4 of the invention, the pigment or dye was red and titanium oxide was included. The ball lacked a pastel feel.
In Comparative Example 3, compared with Examples 3 and 4 of the invention, the pigment or dye was blue, but titanium oxide was not included. As a result, the total light transmittance and diffusion transmittance were high. The ball left a slight impression of transparency, but lacked an elegant feel.
In Comparative Example 4, compared with Example 1 of the invention, the intermediate layer was changed to one having a small L* value. As a result, although the ball left an impression of transparency, the color of the intermediate layer showed through, resulting both in a lack of a pastel feel and a lack of an elegant feel.
Japanese Patent Application No. 2010-176316 is incorporated herein by reference.
Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.

Claims

1. A colored golf ball comprising a core, a cover of at least one layer encasing the core, and a coat of paint applied to a surface of an outermost layer of the cover, wherein the outermost cover layer is formed of a resin composition comprising:

(a) a thermoplastic resin,

(b) a color pigment or dye,

(c) titanium oxide, and

(d) a lubricant,

the resin composition having a total light transmittance of at least 1.0 but not more than 40 and a diffuse transmittance of at least 1.0 but not more than 40, and wherein the paint coat contains a polarizing pigment.

2. The colored golf ball of claim 1, wherein the color pigment or dye (b) is selected from the group consisting of red pigments, blue pigments, yellow pigments, green pigments, violet pigments and black pigments.

3. The colored golf ball of claim 1, wherein the resin composition is formulated as follows:

(a) from 90 to 99 wt % of a thermoplastic resin,

(b) from 0.003 to 2 wt % of a color pigment or dye,

(c) from 0.01 to 2.5 wt % of titanium oxide, and

(d) from 0.1 to 5.5 wt % of a lubricant.

4. The colored golf ball of claim 1, wherein the ball has a surface with a color tone which, expressed numerically in the L*a*b* color space according to JIS Z8729, is:

L*=50 to 95,

a*=−20 to 30, and

b*=−45 to 45.

5. The colored golf ball of claim 1, wherein the paint coat comprises 100 parts by weight of a base resin, from 0.05 to 1 part by weight of a fluorescent whitener and from 0.1 to 3 parts by weight of a polarizing pigment, and the fluorescent whitener and polarizing pigment have a weight ratio therebetween of from 0.05 to 5.0.