US20200001138A1

US20200001138A1 - Golf ball

Info

Publication number: US20200001138A1
Application number: US16/442,639
Authority: US
Inventors: Hirotaka Shinohara; Kae Iizuka; Atsushi Namba
Original assignee: Bridgestone Sports Co Ltd
Current assignee: Bridgestone Sports Co Ltd
Priority date: 2018-06-29
Filing date: 2019-06-17
Publication date: 2020-01-02
Also published as: JP7102982B2; JP2020000627A

Abstract

In a golf ball having a core of at least one layer and a paint film of at least one layer, at least one layer of the paint film includes delustering particles and the same or a differing layer of the paint film includes an effect pigment. The ball is a matte golf ball that is free of luster and gloss and moreover has a quality look.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2018-124393 filed in Japan on Jun. 29, 2018, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a golf ball having a core of at least one layer and a paint film layer (also referred to as a “coating layer”). More specifically, the invention relates to a golf ball that has a matte, gloss-free appearance with a quality feel.

BACKGROUND ART

A number of golf balls possessing a distinctive appearance with a quality feel have been described in the art. One example, disclosed in JP-A 2016-214326, is a golf ball having a paint film layer in which an effect pigment for enhancing the appearance qualities is included within a resin material. However, although golf balls with such a paint film layer have a quality feel, a serious drawback is that they are highly light-scattering and irritate the eyes during putting on the green, which interferes with concentration.
In addition, so-called matte golf balls which have an appearance that is colored but are delustered or free of gloss to such a degree that dimple contours on the surface of the ball cannot be discerned have been popular recently. Such matte golf balls are colored golf balls which have a novel coloration and, although the dimples are not clearly visible, the balls reportedly have a psychological effect that increases the player's concentration on the ball when hitting the ball on shots with a driver and on approach shots, thereby increasing the golf competitiveness.
However, although such matte golf balls do have a psychological effect, they leave something to be desired in terms of quality feel.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a golf ball which has a quality feel, yet also has a psychological effect in that it increases the player's concentration and thus enhances his or her competitiveness.
As a result of extensive investigations, we have discovered that, in a golf ball having a core of at least one layer and a paint film of at least one layer, by including delustering particles in at least one paint film layer and by including an effect pigment in the same or a differing layer of the paint film, the player's concentration on the ball at the time of ball impact can be increased and the ball can be given a distinctive appearance with a quality feel.
Accordingly, the present invention provides a golf ball having a core of at least one layer and a paint film of at least one layer, wherein at least one layer of the paint film includes delustering particles and the same or a differing layer of the paint film includes an effect pigment.
In a preferred embodiment of the golf ball of the invention, the paint film preferably includes the effect pigment in the same layer as the layer which includes the delustering particles.
In another preferred embodiment, the paint film has a two-layer construction consisting of a white paint film layer and a topcoat layer formed directly on the white paint film layer, which topcoat layer includes the delustering materials and the effect pigment.
In yet another preferred embodiment, the golf ball additionally has, as a constituent member, a white cover layer, and the paint film is a single layer formed directly on the white cover layer and includes the delustering particles and the effect pigment.
In still another preferred embodiment of the inventive golf ball, the paint film has a two-layer construction consisting of an inner layer and an outer layer, the inner layer including the effect pigment and the outer layer including the delustering particles.
In another preferred embodiment, the delustering particles (a) and the effect pigment (b) included in the paint film have a weight ratio therebetween, expressed as (a)/(b), which is from 0.3 to 5.0.
In a further preferred embodiment, the effect pigment is glass flakes or mica.
In a still further preferred embodiment, the paint film has a reflectance of 2.5 or less, as measured with a glossmeter at an angle of incidence of 20°.
In a yet further preferred embodiment, the paint film has a reflectance of 6.0 or less, as measured with a glossmeter at an angle of incidence of 60°.
In an additional preferred embodiment, the paint film has a reflectance of 15.0 or less, as measured with a glossmeter at an angle of incidence of 85°.

ADVANTAGEOUS EFFECTS OF THE INVENTION

The golf ball of the invention, because it is provided with a matte finish, helps prevent reduced competitiveness due to diminished player concentration and has a distinctive appearance with a quality feel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects, features and advantages of the invention will become more apparent from the following detailed description.
The golf ball of the invention has a core of at least one layer and a paint film of at least one layer.
The core may be formed using a known rubber material as the base material. Known base rubbers, such as natural rubber or synthetic rubber, may be used as the base rubber. More specifically, the use of polybutadiene, especially cis-1,4-polybutadiene having a cis structure content of at least 40%, is recommended. If desired, natural rubber, polyisoprene rubber, styrene-butadiene rubber and the like may be used together with the foregoing polybutadiene in the base rubber. The polybutadiene may be synthesized with, for example, a titanium-based, cobalt-based, nickel-based or neodymium-based Ziegler-type catalyst or with a cobalt, nickel or other metal catalyst.
Co-crosslinking agents such as unsaturated carboxylic acids and metal salts thereof, inorganic fillers such as zinc oxide, barium sulfate and calcium carbonate, and organic peroxides such as dicumyl peroxide and 1,1-bis(t-butylperoxy)cyclohexane may be included in the base rubber. If necessary, commercial antioxidants and the like may also be suitably added.
A cover of at least one layer may be formed over the core as a core-encasing member. In the case of a two-layer cover, the inner layer is called the intermediate layer and the outer layer is called the outermost layer. In the case of a three-layer cover, the respective layers are called, in order from the inner side: the envelope layer, the intermediate layer and the outermost layer.
The materials making up the cover layers are exemplified by, without particular limitation, resins that have hitherto been used as golf ball materials, such as ionomeric resins, polyester resins, polyurethane resins, polyamide resins, polyolefin resins, olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers. Ionomeric resins are especially suitable and preferably include, for example, either of (a) and (b) below: (a) an ethylene-α,β-unsaturated carboxylic acid copolymer and/or a metal salt thereof, (b) an ethylene-α,β-unsaturated carboxylic acid-α,β-unsaturated carboxylic acid ester copolymer and/or a metal salt thereof.
Specific examples of the α,β-unsaturated carboxylic acid in components (a) and (b) include acrylic acid, methacrylic acid, maleic acid and fumaric acid. Acrylic acid and methacrylic acid are especially preferred. The α,β-unsaturated carboxylic acid ester in component (b) is preferably a lower alkyl ester of the above unsaturated carboxylic acid, specific examples of which include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate. Butyl acrylate (butyl n-acrylate, butyl i-acrylate) is especially preferred.
Metal ion neutralization products of the copolymers in components (a) and (b) can be obtained by partially neutralizing acid groups on the olefin-unsaturated carboxylic acid copolymer or the olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer with metal ions. Illustrative examples of metal ions which neutralize the acid groups include Na⁺, K⁺, Li⁺, Zn⁺⁺, Cu⁺⁺, Mg⁺⁺, Ca⁺⁺, Co⁺⁺, Ni⁺⁺ and Pb⁺⁺. Preferred use can be made of Na⁺, Li⁺, Zn⁺⁺, Mg⁻⁺ and Ca⁻⁺ in particular. Such neutralization products may be obtained by a known method. For example, a neutralization product may be obtained by using, for reaction with the above copolymer, a compound such as a formate, acetate, nitrate, carbonate, bicarbonate, oxide, hydroxide or alkoxide of the above metal ion.
Known substances may be used as components (a) and (b). Illustrative examples include commercial products such as the following acid copolymers: Nucrel® N1560, Nucrel® N1214, Nucrel® N1035, Nucrel® AN4221C, Nucrel® AN4311, Nucrel® AN4318 and Nucrel® AN4319 (all products of DuPont-Mitsui Polychemicals Co., Ltd.). Illustrative examples of metal ion neutralization products of acid copolymers include Himilan® 1554, Himilan® 1557, Himilan® 1601, Himilan® 1605, Himilan® 1706, Himilan® AM7311, Himilan® 1855, Himilan® 1856 and Himilan® AM7316 (all products of DuPont-Mitsui Polychemicals Co., Ltd.), and Surlyn® 7930, Surlyn® 6320, Surlyn® 8320, Surlyn® 9320 and Surlyn® 8120 (E.I. DuPont de Nemours and Company).
The resin material for the outermost layer of the cover may include a colorant comprising a fluorescent dye or fluorescent pigment and a white pigment such as titanium oxide. That is, in order to finish the ball to a colored ball whose surface is free of luster and soft-toned, a colorant comprising a fluorescent dye or fluorescent pigment may be included in the outermost layer-forming resin material. Color is imparted to the outermost layer of the cover by suitably including a known fluorescent dye or fluorescent pigment as the colorant. Examples include solvent yellow, solvent orange, anthraquinone and phthalocyanine (all of which are dyes), and also yellow fluorescent pigments, pink fluorescent pigments and orange fluorescent pigments. Known commercial products may be used as these colorants.
In cases where such a colorant is used, it is preferable to employ a fluorescent colorant that is light harvesting. Light-harvesting fluorescent colorants are materials which have the ability to collect sunlight and convert the wavelength to the long-wavelength side as fluorescent light. These materials are characterized in that they collect light by totally reflecting it at the interior of the colored material and guiding it to the dimple edges, where the light is emitted in a concentrated state and intensely colored.
Such light-harvesting fluorescent colorants include systems that generate orange, pink, red, yellow, blue or violet colors. Commercial products may be used in any of these chromogenic systems. Examples of light-harvesting fluorescent dyes that may be used include those available from BASF under the trade names Lumogen F Yellow 083, Lumogen F Orange 240, Lumogen F Red 305 and Lumogen F Blue 650, and those available from Kashinomoto Technologies Co., Ltd. under the trade names Lumicolor Red, Smart Color LP Green, Smart Color LP Yellow and Smart Color LP Orange.
The amount of the above colorant included per 100 parts by weight of the outermost layer-forming resin material is from 0.001 to 0.2 part by weight, and preferably from 0.005 to 0.1 part by weight. When this amount is low, the fluorescence may weaken and the desired decorativeness may not be obtained. On the other hand, when this amount is high, migration of the colorants, especially dyes, may arise, staining objects that come into contact with the golf ball.
When a white pigment is used, illustrative examples of such pigments include titanium oxide, zinc oxide and barium sulfate. From the standpoint of hiding power and corrosion resistance, the use of titanium oxide is preferred. In this invention, as subsequently discussed, an effect pigment is included in the paint film (coating layer). However, when the cover outermost layer underlying the paint film (coating layer) has a color other than white, the coexistence of that color with the color of the effect pigment makes it difficult to achieve the desired color at the ball's surface. Also, depending on the amount of delusterant such as silica that is included, the paint film may become milky white. Here too, when the color of the substrate underlying the paint film is a color other than white, achieving the desired color at the ball surface is difficult. Accordingly, the cover outermost layer underlying the paint film (coating layer) is preferably white in color.
Also, when a white pigment is used, the amount included per 100 parts by weight of the resin material in the outermost layer is from 1.0 to 10.0 parts by weight, and preferably from 2.0 to 5.0 parts by weight. When this amount is low, the desired white color may not be obtained. On the other hand, when this amount is high, the durability of the layer containing the white pigment may decrease.
An inorganic filler or organic filler may be included in the outermost layer-forming resin material. When an inorganic filler is used, examples of such materials include, without particular limitation, calcium carbonate and silica.
When an organic filler is used, examples of such materials include, without particular limitation, fine particles of crosslinked polymethyl methacrylate (crosslinked PMMA), crosslinked polybutyl methacrylate, crosslinked polyacrylate ester, crosslinked acrylic-styrene copolymer, melamine resin or polyurethane.
The amount of the inorganic filler or organic filler added per 100 parts by weight of the above resin material is from 0.01 to 1.0 part by weight, and preferably from 0.02 to 0.2 part by weight. When too much is added, the hiding properties may become excessive, detracting from a ball design having a quality feel, or the change in color when color fading occurs due to sunlight exposure may increase.
In addition, various additives may be optionally included in the resin composition. For example, pigments, dispersants, antioxidants, light stabilizers, ultraviolet absorbers and lubricants may be suitably added.
The resin composition can be obtained by mixing together the above ingredients using, for example, any of various types of mixers, such as a kneading-type single-screw or twin-screw extruder, a Banbury mixer or a kneader.
Numerous dimples of one, two or more types may be formed on the surface of the outermost layer. The shapes, diameters, depths, number, surface occupancy and other characteristics of the dimples may be suitably selected.
The golf ball of the invention has a paint film (coating layer) which is formed using a paint composition containing delustering particles.
The paint composition is not particularly limited, although it is preferable to use a urethane-based paint. Because the paint film must be capable of enduring the harsh conditions of golf ball use, a two-part curable urethane paint, especially a non-yellowing urethane paint, is preferred.
In the case of a two-part curable urethane paint, various polyols such as saturated polyester polyols, acrylic polyols or polycarbonate polyols may be used as the base resin, and non-yellowing polyisocyanates such as adducts, biurets or isocyanurates of hexamethylene diisocyanate, isophorone diisocyanate or hydrogenated xylylene diisocyanate, or mixtures thereof, may be used as the isocyanate.
Exemplary delustering particles include silica particles, melamine particles and acrylic particles. Specific examples include silica, polymethyl methacrylate, polybutyl methacrylate, polystyrene and polybutyl acrylate. The delustering particles may be organic particles or inorganic particles, with the use of silica particles being especially preferred.
From the standpoint of light-quenching properties and coating properties, the delustering particles have a specific surface area, expressed as the BET specific surface area, of preferably from 200 to 400 m²/g.
Also, from the standpoint of the spin performance of the ball and the light-quenching properties, the delustering particles have an average primary particle size of preferably from 1.0 to 3.0 μm. When this value exceeds 3.0 μm, the ball surface becomes rough, which has an adverse effect on the spin performance and may even lower the performance. On the other hand, when this value is too small, the light-quenching effect may diminish.
The content of such delustering particles per 100 parts by weight of the base resin (combined amount of resin ingredients and solvent) in the paint composition may be set to preferably from 5 to 10 parts by weight. When this content is too high, the viscosity of the paint composition rises and the painting operation tends to become more difficult to carry out. When it is too low, the light-quenching effect may diminish.
The effect pigment is included in the same layer of the paint film as that containing the delustering particles or is included in a different layer of the paint film. It is especially preferable for the effect pigment to be included in the same layer as that containing the delustering particles.
Various types of effect pigments may be used, although preferred effect pigments include, for example, metal powder pigments, glass flakes, mica and pearlescent pigments. Specific examples of metal powder pigments that can be used include aluminum powder, bronze powder, stainless steel powder and nickel powder. Of these, aluminum powder is preferred because, when used together with a color pigment or dye, the color tone is easily adjusted. Examples of such aluminum pigments that may be used include the commercial products available under the trade names “Aluminum Paste Highprint TD200T” and “Metasheen Slurry KM100” (both manufactured by Toyo Aluminum K.K.). Pearlescent pigments are broadly divided into 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 general, titanium dioxide and iron oxide are commonly used as the metal oxide; by varying the coverage (thickness of the metal oxide coating), various colors and interference effects can be achieved. The larger the particle size of these pigments, the greater the degree of luster that can be achieved. However, at a larger pigment particle size, the luster has a tendency to subside. Hence, it is necessary to select a pigment having a suitable particle size within a range that does not detract from the advantageous effects of the invention.
The content of effect pigment per 100 parts by weight of the base resin (combined amount of resin ingredients and solvent) in the paint composition for the paint film may be set to preferably from 1.0 to 10.0 parts by weight. When this content is too high, during spray painting, for example, the paint propelling ability of the spray gun decreases, which may make the painting operation more difficult to carry out. When this content is too low, it may not be possible to obtain the quality ball appearance that is desired.
The delustering particles (a) and effect pigment (b) included in the paint film have a weight ratio therebetween, expressed as (a)/(b), which, to achieve a good balance between the ball surface luster-suppressing effect and a quality feel, is preferably from 0.3 to 5.0, and more preferably from 1.0 to 2.5. At a weight ratio below this range, it may not be possible to suppress the luster of the golf ball surface; at a weight ratio above this range, a quality feel may not be achieved.
Specific paint film configurations include embodiments in which the paint film consists of a single layer, in which case the effect pigment is included in the same layer as that which includes the delustering particles; and embodiments in which the paint film consists of two layers, in which case the effect pigment is included in the inner layer and the delustering particles are included in the outer layer.
The layer structure of the paint film may be a two-layer structure consisting of a white paint film layer and a topcoat layer formed directly on the white paint film layer. In this case, the delustering particles and the effect pigment may both be included in the topcoat layer.
When the paint film is a single layer, the golf ball in a preferred embodiment includes, as a constituent member, a white cover layer, and a single-layer or multilayer paint film is formed directly on the white cover layer. Depending on the content of delusterant such as silica, the paint film may become milky white. When the color of the substrate underlying the paint film is a color other than white, it may be difficult to achieve the desired color at the ball surface. Hence, it is preferable for the outermost layer of the cover serving as the underlying substrate of the paint film to be white.
The paint film (coating layer) has a reflectance, as measured with a glossmeter, which is 2.5 or less at an angle of incidence of 20°, 6.0 or less at an angle of incidence of 60°, and 15.0 or less at an angle of incidence of 85°. With a coating layer optimized so that these reflectances satisfy the indicated ranges, a delustering effect can be imparted. The conditions for measuring the reflectance with a glossmeter involve measurement with the instrument used in the subsequently described examples on an ABS resin plate to which the coating layer has been applied to a thickness of 20 μm.
Ball specifications such as the ball weight and diameter may be suitably set in accordance with the Rules of Golf.

EXAMPLES

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

Working Examples 1 to 5, Comparative Examples 1 to 3

As shown in Table 1 below, the solid core in each Example was produced by using the following rubber composition, which is common to all the Examples, and vulcanizing for 15 minutes at 155° C.

	TABLE 1

		Common to all
	Rubber composition for core	Working and
	(parts by weight)	Comparative Examples

	Polybutadiene rubber	100
	Organic peroxide	1
	Barium sulfate	16
	Zinc oxide	4
	Zinc acrylate	30
	Zinc salt of pentachlorothiophenol	0.3

Details on the above core materials are given below.

Polybutadiene: Available under the trade name “BRO1” from JSR Corporation
Organic peroxide: Dicumyl peroxide, available as “Percumyl D” from NOF Corporation
Barium sulfate: Available from Sakai Chemical Co., Ltd.
Zinc oxide: Available from Sakai Chemical Co., Ltd.
Zinc acrylate: Available from Nippon Shokubai Co., Ltd.
Zinc salt of pentachlorothiophenol: Available from Wako Pure Chemical Industries, Ltd.

Formation of Cover (Intermediate Layer and Outermost Layer)

Next, an intermediate layer-encased sphere having a diameter of 40 mm was produced by injection molding the intermediate layer-forming resin material shown in Table 2 below, which is common to all the Examples, to a thickness of 1.35 mm over the 37.3 mm diameter core obtained as described above. A three-piece golf ball having a ball diameter of 42.7 mm was then manufactured by injection-molding the outermost layer-forming material shown in the same table to a thickness of 1.35 mm over the intermediate layer-encased sphere. A common dimple configuration was formed at this time on the surface of the outermost layer in each Working Example and Comparative Example.

TABLE 2

	Common to all
	Working and
Resin material (parts by weight)	Comparative Examples

Cover	Intermediate layer	HPF 1000	100
	Outermost layer	Himilan 1601	50
		Himilan 1557	50
		Magnesium stearate	1
		Titanium oxide	2.8

Details on the materials in the table are given below.

HPF 1000: An ionomeric resin material available from E.I. DuPont de Nemours and Company
Himilan 1605, Himilan 1557: Ionomeric resins from DuPont-Mitsui Polychemicals Co., Ltd.
Titanium oxide: A white pigment

Next, in each Working Example and Comparative Example, using the two-part curable urethane paint made of a base resin and a curing agent shown in Table 3 below, the surface of the outermost layer of the golf ball was coated to a thickness of 15 μm, thereby forming a single-layer paint film (coating layer).

TABLE 3

	Common to all
	Working and
Resin composition of paint (pbw)	Comparative Examples

Base resin	Saturated polyester polyol	27.5
	(m.w., 28,000)
	Solvent	72.5
	(Combined amount of resin	(100)
	ingredients and solvent)
	Delustering particles	Amounts shown in Table 4
	(silica)	for respective Examples
	Effect pigment
Curing agent	HMDI isocyanurate	42.0
	(low-molecular weight)
	Solvent	58.0

Details on the base resin and curing agent are given in (i) to (iv) below.

(i) First, a reactor equipped with a reflux condenser, a dropping funnel, a gas inlet and a thermometer was charged with 140 parts by weight of trimethylolpropane, 95 parts by weight of ethylene glycol, 157 parts by weight of adipic acid and 58 parts by weight of 1,4-cyclohexanedimethanol, following which the temperature was raised to between 200 and 240° C. under stirring and the reaction was effected by 5 hours of heating. This yielded a saturated polyester polyol having an acid value of 4, a hydroxyl value of 170 and a weight-average molecular weight (Mw) of 28,000.
(ii) Next, the polyester polyol synthesized above was dissolved in butyl acetate, thereby preparing a varnish having a nonvolatiles content of 70 wt %.
(iii) The base resin was prepared by dissolving 27.5 parts by weight of the saturated polyester polyol with the butyl acetate (the nonvolatiles content of this solution was 27.5 wt %), and mixing in silica (“Finesil X-35” available from Maruo Calcium Co., Ltd.; average primary particle size, 2.4 μm; BET specific surface area, 262 m²/g) as the delustering particles and natural mica (Iriodin 7205, from Sano Paint Co., Ltd.) as the effect pigment.
(iv) Next, the isocyanate shown in Table 3 was dissolved in an organic solvent and used as the curing agent. That is, HDI isocyanurate (available as Duranate™ TPA-100 from Asahi Kasei Corporation; NCO content, 23.1 wt %; nonvolatiles content, 100 wt %) and, as organic solvents, ethyl acetate and butyl acetate were added in the proportions shown in Table 3, thereby preparing a resin composition for use as a paint.

The glossiness and quality feel of the golf balls thus obtained in each Working Example and Comparative Example were measured and evaluated. The results are shown in Table 4 below.

Glossiness

The glossiness of the paint film (coating layer) at the golf ball surface was evaluated as follows. The degrees of gloss at incident angles of 20°/60°/85° were measured with the BYK Micro-TRI-Gloss Meter. When the numerical values for degree of gloss at the respective measurement angles were 2.5 or less at an incident angle of 20°, 6.0 or less at an incident angle of 60° and 15.0 or less at an incident angle of 85°, the glossiness was sufficiently suppressed and thus rated as excellent (“Exc”). When the degree of gloss was from 2.6 to 5.0 at an incident angle of 20°, from 6.1 to 20.0 at an incident angle of 60° and from 15.1 to 40.0 at an incident angle of 85°, the glossiness was somewhat suppressed and thus rated as “Good.” Otherwise, the glossiness was rated as “NG.”

Quality Feel

The quality feel was visually assessed by 30 golfers and rated according to the following criteria.
Exc: At least 25 out of 30 golfers thought the ball had a quality feel.
Good: From 15 to 24 out of 30 golfers thought the ball had a quality feel.
Fair: From 6 to 14 out of 30 golfers thought the ball had a quality feel.
NG: Five or fewer out of 30 golfers thought the ball had a quality feel.

TABLE 4

		Comparative
	Working Example	Example

				1	2	3	4	5	1	2	3

Coating	Formulation	Base	Saturated polyester	27.5	27.5	27.5	27.5	27.5	27.5	28.0	27.5
layer	(pbw)	resin	polyol
			(m.w., 28,000)
			Solvent	72.5	72.5	72.5	72.5	72.5	72.5	72.0	72.5
			Combined amount	100	100	100	100	100	100	100	100
			(resin ingredients +
			solvent)
			Delustering particles (a)	9.0	6.0	15.0	2.0	9.0	9.0
			Effect pigment (b)	6.0	6.0	6.0	9.0	2.0			6.0
			(a)/(b)	1.5	1.0	2.5	0.2	4.5	—	—	—
		Curing	HMD isocyanurate	42.0	42.0	42.0	42.0	42.0	42.0	42.0	42.0
		agent	(low-molecular-weight)

Glossiness	Solvent	58.0	58.0	58.0	58.0	58.0	58.0	58.0	58.0
	Glossmeter incident	1.9	2.1	1.5	3.5	1.3	1.2	60.0	80.6
	angle, 20°
	Glossmeter incident	3.7	5.8	3.0	12.3	2.5	2.1	80.0	96.9
	angle, 60°
	Glossmeter incident	9.8	12.2	6.8	35.0	4.8	3.2	95.0	98.0
	angle, 85°
	Rating	Exc	Exc	Exc	Good	Exc	Exc	NG	NG

Ball appearance: quality feel	Exc	Exc	Exc	Exc	Good	NG	NG	Exc

The results in Table 4 show that the golf balls obtained in Working Examples 1 to 5 according to the invention were matte golf balls in which the paint film had substantially no luster, which balls had a quality feel.
By contrast, the golf ball in Comparative Example 1 was a golf ball that had a matte look but lacked a quality feel.
The golf ball in Comparative Example 2 had an appearance that lacked both a matte look and a quality feel.
The golf ball in Comparative Example 3 had a quality feel but a matte appearance.
Japanese Patent Application No. 2018-124393 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 golf ball comprising a core of at least one layer and a paint film of at least one layer, wherein at least one layer of the paint film includes delustering particles and the same or a differing layer of the paint film includes an effect pigment.

2. The golf ball of claim 1, wherein the paint film includes the effect pigment in the same layer as the layer which includes the delustering particles.

3. The golf ball of claim 1, wherein the paint film has a two-layer construction consisting of a white paint film layer and a topcoat layer formed directly on the white paint film layer, which topcoat layer includes the delustering particles and the effect pigment.

4. The golf ball of claim 1, further comprising, as a constituent member, a white cover layer, wherein the paint film is a single layer formed directly on the white cover layer and includes the delustering particles and the effect pigment.

5. The golf ball of claim 1, wherein the paint film has a two-layer construction consisting of an inner layer and an outer layer, the inner layer including the effect pigment and the outer layer including the delustering particles.

6. The golf ball of claim 1, wherein the delustering particles (a) and the effect pigment (b) included in the paint film have a weight ratio therebetween, expressed as (a)/(b), which is from 0.3 to 5.0.

7. The golf ball of claim 1, wherein the effect pigment is glass flakes or mica.

8. The golf ball of claim 1, wherein the paint film has a reflectance of 2.5 or less, as measured with a glossmeter at an incident angle of 20°.

9. The golf ball of claim 1, wherein the paint film has a reflectance of 6.0 or less, as measured with a glossmeter at an incident angle of 60°.

10. The golf ball of claim 1, wherein the paint film has a reflectance of 15.0 or less, as measured with a glossmeter at an incident angle of 85°.