Resin composition for golf ball and its cover or top coat

Abstract

To provide a golf ball and a resin composition for a cover or a topcoat thereof which make a ball surface shine by being exposed to ultraviolet rays even if a naturally derived substance is used as a fluorescent material, and are environmentally and human friendly.SOLUTION: A resin composition for a cover or a topcoat of a golf ball of the present invention contains: a resin for a cover or a topcoat; and a plant or algae-derived extract that emits light by using light as an energy source for a fluorescent material. In the golf ball in the present invention, the cover or the topcoat is formed by using the resin composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition for a golf ball and its cover or top coat, and more particularly to a resin composition for a golf ball and its cover or top coat having an improved fluorescent whitening agent (fluorescent material). [Background technology]

[0002] Although golf balls with colorful or patterned exteriors are available, typical golf balls are white and have markings such as the golf ball manufacturer's name, brand name, logo, numbers, etc. White golf balls are usually manufactured by blending a white pigment into the resin of the cover in which the dimples are formed, and then forming a colorless and transparent top coat on the surface of this cover.

[0003] The resin of a golf ball cover is prone to yellowing when exposed to sunlight, so in order to prevent such yellowing, the cover or the top coat thereof may be compounded with an ultraviolet absorbing agent that absorbs the ultraviolet rays in sunlight, or, in order to make the white color stand out more, a fluorescent whitening agent that absorbs ultraviolet rays and emits visible light of a specified wavelength may be compounded.

[0004] For example, Japanese Patent Application Laid-Open No. 2000-516521 lists coumarin, oxazinone, stilbene, naphthalene compounds, pyrazoline, and derivatives thereof as optical brighteners that absorb UV light and emit visible light to improve the visibility and appearance of the ball. It also describes that stilbene derivatives, styryl derivatives of benzene, biphenyl, bis(benzazol-2-yl) derivatives, coumarin, carbostyrils, naphthalimide, derivatives of dibenzothiophene-5,5-dioxide, pyrene derivatives, and pyridotriazoles have been used as optical brighteners in the past.

[0005] Furthermore, JP 2010-246642 A describes an invention relating to a colored golf ball, which gives an example of the type of fluorescent pigment blended into the cover, which is an organic fluorescent pigment obtained by coloring an amino resin or acrylic resin base resin with a colorant selected from the group consisting of xanthene (red / pink), acridine (yellow), quinoline (yellow), thiazole (yellow) and aminoketone (yellow) pigments.

[0006] On the other hand, Japanese Patent Application Laid-Open No. 8-318186 discloses a method of measuring the thickness of a coating film containing a fluorescent whitening agent on the surface of a golf ball by irradiating the golf ball with ultraviolet light and capturing the secondary light emitted by the golf ball with a CCD camera and processing the image to obtain a light-dark image of the coating film and then measuring the thickness of the coating film from the light-dark image. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2000-516521 A [Patent Document 2] JP 2010-246642 A [Patent Document 3] Japanese Patent Application Publication No. 8-318186 Summary of the Invention [Problem to be solved by the invention]

[0008] The optical brighteners (fluorescent dyes) and fluorescent pigments used in golf balls, including those described in the above-mentioned documents, are all petroleum-derived chemical substances, and natural substances are desired in consideration of the depletion of fossil fuels and the human body and the environment. Mineral-derived pigments such as gypsum, fluorite, and calcite are known to emit fluorescence and may be used as inorganic fluorescent pigments. However, as described in JP 2010-246642 A, although inorganic fluorescent pigments can be used to color golf ball covers, they are poorly soluble in golf ball paints, which are organic materials, and therefore lose transparency and wear resistance.

[0009] In view of the above problems, the present invention has an object to provide a golf ball and a resin composition for its cover or top coat that uses a naturally occurring fluorescent material, but which causes the ball surface to shine when exposed to ultraviolet light, and which is safe for the human body and the environment. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, one aspect of the present invention is a golf ball having at least a core, a cover, and a top coat, wherein the cover or the top coat contains an extract derived from a plant or algae that emits light using light as an energy source.

[0011] The plant or algae-derived extract is preferably curcumin, ferulic acid, ferulic acid compounds, spirulina, anthocyanin, quinine, phycocyanin, chlorophyll, or a combination thereof.

[0012] The plant or algae-derived extract preferably has an absorbance peak at a wavelength between 350 nm and 450 nm.

[0013] When the plant or algae-derived extract is included in the top coat, the top coat preferably comprises an oil-based paint.

[0014] Furthermore, in another aspect, the present invention provides a resin composition for a cover or top coat of a golf ball, the resin composition comprising a resin for the cover or top coat of a golf ball and an extract derived from a plant or algae that emits light using light as an energy source.

[0015] The resin for the top coat preferably includes a urethane paint containing a base agent and a curing agent, and the content of the plant or algae-derived extract is preferably within the range of 0.01 to 5.0 mass % relative to the total amount of the base agent including the solvent.

[0016] The solvent is preferably an ester-based solvent or a ketone-based solvent. Effect of the Invention

[0017] Thus, according to the present invention, by blending a plant or algae-derived extract that uses light as an energy source to emit light in the resin composition of a golf ball cover or top coat, the golf ball cover or top coat can shine when exposed to ultraviolet light, thereby providing a golf ball that uses a naturally occurring substance as the fluorescent material and is friendly to the human body and the environment. Also, in a golf ball film thickness measurement test using a fluorescent whitening agent, the plant or algae-derived extract acts as a fluorescent material, allowing the thickness of the cover or top coat to be measured with high accuracy.

[0018] Furthermore, curcumin, spirulina, anthocyanin, etc., which are extracts derived from plants or algae that emit light using light as an energy source, absorb light and emit light without impairing the gloss or color tone of the golf ball, and can be blended into the resin composition of the cover or top coat of the golf ball, which is an organic material. In particular, curcumin, ferulic acid compounds, spirulina, and chlorophyll are oil-soluble, and can be blended into the resin for the top coat by using an oil-based paint such as a urethane paint containing a base agent and a hardener as the resin for the top coat. By using an ester-based solvent or a ketone-based solvent as the solvent for the resin for the top coat, instead of an aromatic solvent that is bad for the human body and the environment, a golf ball that is more friendly to the human body and the environment can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the golf ball and the resin composition for the cover or top coat thereof according to the present invention will be described in detail.

[0020] The resin composition for a cover or top coat of this embodiment contains a resin for a golf ball cover or top coat and a fluorescent brightening agent (fluorescent material) derived from a plant or algae (also called a "phytochemical") that emits light using light as an energy source.

[0021] The resin for the cover may be, but is not limited to, for example, a thermoplastic polyurethane, an ionomer resin, or a mixture thereof as a main component.

[0022] The structure of the thermoplastic polyurethane material is composed of a soft segment made of a polymer polyol (polymeric glycol) and a chain extender and a polyisocyanate that constitute a hard segment. Here, the polymer polyol used as the raw material is not particularly limited, but in the present invention, polyester polyols and polyether polyols are preferred. Specific examples of polyester polyols include adipate polyols such as polyethylene adipate glycol, polypropylene adipate glycol, polybutadiene adipate glycol, and polyhexamethylene adipate glycol, and lactone polyols such as polycaprolactone polyol. Examples of polyether polyols include poly(ethylene glycol), poly(propylene glycol), and poly(tetramethylene glycol).

[0023] The chain extender is not particularly limited, but in the present invention, a low molecular weight compound having two or more active hydrogen atoms in the molecule capable of reacting with an isocyanate group and a molecular weight of 2,000 or less can be used, and among these, an aliphatic diol having 2 to 12 carbon atoms is preferred. Specific examples include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, and the like, and among these, 1,4-butylene glycol is particularly preferred.

[0024] The polyisocyanate compound is not particularly limited, but in the present invention, for example, one or more compounds selected from the group consisting of 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, naphthylene 1,5-diisocyanate, tetramethylxylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, and dimer acid diisocyanate can be used. However, depending on the type of isocyanate, it may be difficult to control the crosslinking reaction during injection molding. Therefore, in the present invention, from the viewpoint of the balance between stability during production and the physical properties exhibited, the aromatic diisocyanate 4,4'-diphenylmethane diisocyanate is preferred.

[0025] The ionomer resin may be, but is not limited to, one having the following component (a) and / or component (b) as the base resin. Optionally, the following component (c) may be added to this base resin. The component (a) is an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer and / or a metal salt thereof, the component (b) is an olefin-unsaturated carboxylic acid binary random copolymer and / or a metal salt thereof, and the component (c) is a thermoplastic block copolymer having a polyolefin crystalline block and a polyethylene / butylene random copolymer.

[0026] In addition to the main component of the thermoplastic polyurethane or ionomer resin, the resin for the cover may contain a thermoplastic resin or elastomer other than the thermoplastic polyurethane. Specifically, one or more of polyester elastomers, polyamide elastomers, ionomer resins, styrene block elastomers, hydrogenated styrene butadiene rubber, styrene-ethylene / butylene-ethylene block copolymers or modified products thereof, ethylene-ethylene / butylene-ethylene block copolymers or modified products thereof, styrene-ethylene / butylene-styrene block copolymers or modified products thereof, ABS resins, polyacetals, polyethylene, and nylon resins may be used. In particular, polyester elastomers, polyamide elastomers, and polyacetals are preferably used because they maintain good productivity while improving resilience and abrasion resistance through reaction with isocyanate groups. When the above components are blended, the blending amount is appropriately selected depending on the adjustment of the hardness of the cover material, the improvement of the resilience, the improvement of the fluidity, the improvement of the adhesion, etc., and is not particularly limited, but is preferably 5 parts by mass or more per 100 parts by mass of the thermoplastic polyurethane component. In addition, the upper limit of the blending amount is also not particularly limited, but is preferably 100 parts by mass or less, more preferably 75 parts by mass or less, and even more preferably 50 parts by mass or less per 100 parts by mass of the thermoplastic polyurethane component. In addition, polyisocyanate compounds, fatty acids or derivatives thereof, basic inorganic metal compounds, fillers, etc. may be added.

[0027] The resin for the top coat is not particularly limited, but for example, a paint resin such as a urethane paint consisting of a polyol as a main agent and a polyisocyanate as a hardener, or a rubber-based paint can be used as the main component. These paint resins are oil-based paints that use organic solvents. In addition to the above main components, the material forming the top coat may contain a low surface energy composition such as silicone wax as an additive. Each component will be described below.

[0028] The polyol is not limited thereto, but it is preferable to use polycarbonate polyol or polyester polyol, and two kinds of polyester polyols, that is, polyester polyol (A) and polyester polyol (B), may be used. When using these two kinds of polyester polyols, the weight average molecular weights (Mw) are different, and it is preferable that the weight average molecular weight (Mw) of the (A) component is 20,000 to 30,000 and the weight average molecular weight (Mw) of the (B) component is 800 to 1,500. The weight average molecular weight (Mw) of the (A) component is more preferably 22,000 to 29,000, and even more preferably 23,000 to 28,000. The weight average molecular weight (Mw) of the (B) component is more preferably 900 to 1,200, and even more preferably 1,000 to 1,100.

[0029] The polyester polyol is obtained by polycondensation of a polyol and a polybasic acid. Examples of the polyol include diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, hexylene glycol, dimethylolheptane, polyethylene glycol, and polypropylene glycol, triols, tetraols, and polyols having an alicyclic structure. Examples of polybasic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid, and dimer acid, aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid, and citraconic acid, aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid, dicarboxylic acids having an alicyclic structure such as tetrahydrophthalic acid, hexahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and endomethylenetetrahydrophthalic acid, and tris-2-carboxyethyl isocyanurate. In particular, polyester polyols having a cyclic structure introduced into the resin skeleton can be used as the polyester polyol of component (A), and examples thereof include polyester polyols obtained by polycondensation of a polyol having an alicyclic structure such as cyclohexanedimethanol with a polybasic acid, or polycondensation of a polyol having an alicyclic structure with a diol or triol with a polybasic acid. On the other hand, as the polyester polyol of component (B), a polyester polyol having a multi-branched structure can be used, and an example thereof includes polyester polyols having a branched structure such as "NIPPOLAN 800" manufactured by Tosoh Corporation.

[0030] In addition, when the above-mentioned polyester polyol is used, the weight average molecular weight (Mw) of the entire base agent is preferably 13,000 to 23,000, more preferably 15,000 to 22,000. In addition, the number average molecular weight (Mn) of the entire base agent is preferably 1,100 to 2,000, more preferably 1,300 to 1,850. If these average molecular weights (Mw and Mn) deviate from the above ranges, the abrasion resistance of the top coat may decrease. The weight average molecular weight (Mw) and the number average molecular weight (Mn) are measured values ​​(polystyrene equivalent values) by gel permeation chromatography (hereinafter abbreviated as GPC) measurement by differential refractometer detection. In the case where two types of polyester polyols are used, the Mw and Mn of the entire base agent are also within the above-mentioned ranges.

[0031] The blending amounts of the above two types of polyester polyols (A) and (B) are not particularly limited, but it is preferable that the blending amount of the (A) component is 20 to 30 mass % based on the total amount of the base material including the solvent, and the blending amount of the (B) component is 2 to 18 mass % based on the total amount of the base material.

[0032] The polyisocyanate is not particularly limited, but may be a commonly used aromatic, aliphatic, alicyclic, or other polyisocyanate, specifically, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 1,4-cyclohexylene diisocyanate, naphthalene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1-isocyanato-3,3,5-trimethyl-4-isocyanatomethylcyclohexane, etc. These may be used alone or in combination.

[0033] Examples of the modified hexamethylene diisocyanate include polyester modified hexamethylene diisocyanate and urethane modified hexamethylene diisocyanate. Examples of the derivatives of hexamethylene diisocyanate include nurate (isocyanurate), biuret, and adduct of hexamethylene diisocyanate.

[0034] In the urethane coating material consisting of polyol and polyisocyanate as main components, the molar ratio (NCO group / OH group) of the hydroxyl group (OH group) of the polyol to the isocyanate group (NCO group) of the polyisocyanate is preferably 0.6 or more as a lower limit, more preferably 0.65 or more. The upper limit of this molar ratio is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.9 or less. If this molar ratio is below the above lower limit, unreacted hydroxyl groups may remain, which may deteriorate the performance and water resistance of the top coat. On the other hand, if the molar ratio exceeds the above upper limit, the isocyanate group becomes excessive, which will react with water to produce urea groups (brittle), which may result in a deterioration of the performance of the top coat.

[0035] As the curing catalyst (organometallic compound) that promotes the reaction between polyol and polyisocyanate, an amine catalyst or an organometallic catalyst can be used. As this organometallic compound, metal soaps such as aluminum, nickel, zinc, tin, etc., which have traditionally been blended as curing agents in two-component curing urethane paints, can be suitably used.

[0036] The polyol, which is the main agent, and the polyisocyanate, which is the curing agent, can be mixed with various organic solvents depending on the coating conditions. Examples of such organic solvents include aromatic solvents such as toluene, xylene, and ethylbenzene, ester solvents such as ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, and propylene glycol methyl ether propionate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ether solvents such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and dipropylene glycol dimethyl ether, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane, and petroleum hydrocarbon solvents such as mineral spirits.

[0037] Among these, aromatic solvents such as toluene and xylene are not good for the human body or the environment, so it is preferable to use ester solvents or ketone solvents. In particular, ester solvents such as butyl acetate and ethyl acetate are more preferable from the viewpoint of easily dissolving plant or algae-derived extracts. Among the plant or algae-derived extracts, curcumin, ferulic acid compounds, etc. are oil-soluble and difficult to dissolve in water.

[0038] As the solvent, an aqueous solvent can be used. For example, the aqueous solvent may contain water, alcohol, etc., and is more gentle to the human body and the environment than an organic solvent. In addition, an aqueous solvent may be used as the solvent for the main agent, and an organic solvent may be used as the solvent for the curing agent, and the like, and an aqueous solvent and an organic solvent may be used in combination. Among the extracts derived from plants or algae, spirulina, chlorophyll, etc. are water-soluble, and an aqueous solvent can be used.

[0039] The fluorescent material used in the golf ball preferably has an absorbance peak at a wavelength between 350 nm and 450 nm. Examples of plant- or algae-derived extracts having an absorbance peak at such wavelengths include, but are not limited to, curcumin, ferulic acid, ferulic acid compounds, spirulina, anthocyanin, quinine, phycocyanin, chlorophyll, etc. Such plant- or algae-derived extracts can absorb light and emit light without impairing the gloss or color of the golf ball.

[0040] Curcumin is extracted from turmeric, etc. Curcumin has an absorbance peak in the wavelength range of 350 to 450 nm.

[0041] Ferulic acid and ferulic acid compounds are contained in grains such as rice, wheat, rye, and barley, and in seeds such as coffee, apple, artichoke, peanut, orange, and pineapple, and are mainly extracted from rice bran. Ferulic acid and ferulic acid compounds have an absorbance peak in the wavelength range of 320 to 360 nm. Examples of ferulic acid compounds include ferulic acid esters such as γ-oryzanol.

[0042] Spirulina is the name of algae that lives in freshwater areas, but it is also called spirulina when it is dehydrated, dried, crushed, and powdered. Spirulina contains three types of pigments: carotenoids, chlorophyll, and phycocyanin. In other words, spirulina contains extracts derived from these three types of algae. Although spirulina contains these three types of pigments, it has an absorbance peak in the wavelength range of 600 to 700 nm as a whole.

[0043] Anthocyanin is a pigment that is widely present in the plant kingdom and is extracted from fruits such as grapes and blueberries. Anthocyanin has an absorbance peak in the wavelength range of 450 to 550 nm.

[0044] Quinine is extracted from the bark of the cinchona tree and has an absorbance peak in the wavelength range of 300 to 350 nm.

[0045] Phycocyanin is widely extracted from algae such as spirulina, blue-green algae, gray algae, red algae, cryptophytes, etc. Phycocyanin has an absorbance peak in the wavelength range of 550 to 650 nm.

[0046] Chlorophyll is widely extracted from algae such as the above-mentioned spirulina as well as from plant leaves. It has absorbance peaks in the wavelength ranges of 400 to 500 nm and 600 to 700 nm.

[0047] In the case of a resin composition for a top coat, the plant or algae-derived extract as a fluorescent material is preferably added to the base resin for the top coat. The amount of the plant or algae-derived extract is sufficient to make the golf ball shine when exposed to ultraviolet light, and is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, based on the total amount of the base resin including the solvent, although this is not limited thereto. In addition, the upper limit of the amount of the plant or algae-derived extract is, for example, but not limited thereto, preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 1.0% by mass or less, because adding too much of the plant or algae-derived extract changes the color tone of the golf ball, and some plant or algae-derived extracts have low solubility in the paint, and insufficient dispersion may affect the appearance and wearability of the golf ball.

[0048] In the case of a resin composition for a cover, the blending amount of the plant or algae-derived extract as a fluorescent material is, for example, but not limited to, preferably 0.5% by mass or more and 5.0% by mass or less relative to the cover base resin.

[0049] In addition, a white pigment, a pearl pigment, a matte material, and the like may be added to the resin composition for the cover or top coat, if necessary.

[0050] Next, one embodiment of a method for producing a golf ball using this resin composition for the cover or top coat will be described.

[0051] The golf ball of the present embodiment may have a multi-piece structure, such as a two-piece structure consisting of a core and a cover, or a three-piece structure having an intermediate layer between the core and the cover.

[0052] The core can be mainly formed of a base rubber. As the base rubber, a wide variety of rubbers (thermosetting elastomers) can be used, including, but not limited to, polybutadiene rubber (BR), styrene butadiene rubber (SBR), natural rubber (NR), polyisoprene rubber (IR), polyurethane rubber (PU), butyl rubber (IIR), vinyl polybutadiene rubber (VBR), ethylene propylene rubber (EPDM), nitrile rubber (NBR), and silicone rubber. As the polybutadiene rubber (BR), for example, 1,2-polybutadiene, cis-1,4-polybutadiene, etc. can be used.

[0053] In addition to the base rubber as the main component, the core may optionally contain, for example, a co-crosslinking agent, a crosslinking agent, a filler, an antioxidant, an isomerizing agent, a mastication accelerator, sulfur, and an organic sulfur compound. Also, instead of the base rubber, a thermoplastic elastomer, an ionomer resin, or a mixture thereof may be used as the main component.

[0054] The core has a substantially spherical shape. The upper limit of the outer diameter of the core is preferably about 42 mm or less, more preferably about 41 mm or less, and even more preferably about 40 mm or less. The lower limit of the outer diameter of the core is preferably about 5 mm or more, more preferably about 15 mm or more, and most preferably about 25 mm or more. The core may be solid or hollow. The core may be a single layer, or may be a core consisting of multiple layers such as a center core and a surrounding layer.

[0055] The core 10 can be molded by a known method for molding a golf ball core. For example, but not limited to, a material containing a base rubber is kneaded in a kneading machine, and then the kneaded mixture is pressure-vulcanized and molded in a round mold to obtain a core having multiple layers. A known method for molding a multi-layered solid core can be used to mold a core having multiple layers. For example, a center core is obtained by kneading a material in a kneading machine and pressure-vulcanizing and molding the kneaded mixture in a round mold, and then a material is kneaded in a kneading machine as an envelope layer, and the kneaded mixture is molded into a sheet, and the sheet is used to cover the center core, and then the sheet is pressure-vulcanized and molded in a round mold to obtain a multi-layered core.

[0056] Next, a cover is formed around the core using a resin composition for the cover that contains an extract derived from a plant or algae as the fluorescent material of the present embodiment. Note that when a resin composition for the top coat that contains an extract derived from a plant or algae as the fluorescent material of the present embodiment is used for forming the top coat, a fluorescent material that does not contain an extract derived from a plant or algae is used for forming the cover.

[0057] The method for forming the cover can be a known molding method for a golf ball cover. For example, but not limited to, the core can be placed in a mold and the resin composition for the cover can be injection molded to form the cover so as to cover the core. The mold for molding the cover has a plurality of protrusions for forming dimples on the cover surface. The size, shape, number, etc. of the dimples formed on the cover surface can be appropriately designed according to the desired aerodynamic characteristics of the golf ball.

[0058] The thickness of the cover is not limited to these values, but the lower limit is preferably 0.2 mm or more, and more preferably 0.4 mm or more, and the upper limit is preferably 4 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less.

[0059] The material hardness of the cover is not limited to, but the upper limit is preferably about 60 or less, more preferably about 55 or less, and even more preferably about 50 or less, in Shore D. The lower limit is preferably about 35 or more, and more preferably about 40 or more, in Shore D. The material hardness of the cover is measured in accordance with the ASTM D2240-95 standard after the resin material for the cover is molded into a sheet having a thickness of 2 mm and allowed to stand for at least two weeks.

[0060] Furthermore, a top coat (also called a "coating") is formed on the outer periphery of the cover using a resin composition for the top coat that contains an extract derived from plants or algae as the fluorescent material of this embodiment. As described above, when a resin composition for the cover that contains an extract derived from plants or algae as the fluorescent material of this embodiment is used to form the cover, a fluorescent material that does not contain an extract derived from plants or algae is used to form the top coat.

[0061] The thickness of the top coat is not particularly limited, but the lower limit is preferably 7 μm or more, more preferably 10 μm or more, and even more preferably 13 μm or more, and the upper limit is preferably 22 μm or less, and more preferably 20 μm or less.

[0062] The method for forming the top coat on the surface of the cover is not particularly limited, and any known method for applying a golf ball paint to the surface of the cover can be used, such as an air gun coating method or an electrostatic coating method.

[0063] An intermediate layer may be provided between the core and the cover. The intermediate layer may be formed using the same material as the cover described above, i.e., thermoplastic polyurethane, ionomer resin, or a mixture thereof. In addition to the main components described above, the intermediate layer may contain other thermoplastic elastomers, polyisocyanate compounds, fatty acids or derivatives thereof, basic inorganic metal compounds, fillers, etc.

[0064] The material hardness of the mid layer is not limited to this, but the lower limit is preferably 50 or more, and more preferably 55 or more, in Shore D. The upper limit of the hardness of the mid layer 40 is preferably 70 or less, and more preferably 65 or less, in Shore D.

[0065] The thickness of the intermediate layer is not limited to this value, but is preferably 0.5 mm or more, and more preferably 1 mm or more. The upper limit of the thickness of the intermediate layer is preferably 10 mm or less, and more preferably 5 mm or less.

[0066] In this manner, a golf ball can be obtained with a cover or top coat that contains a plant or algae-derived extract as a fluorescent material. EXAMPLES

[0067] Examples and comparative examples of the present invention will be described below.

[0068] A top coat for a golf ball was prepared using the coating composition shown in Table 1. The composition in Table 1 is expressed in parts by mass. The coating thickness of the top coat was 15 μm. The prepared golf ball was then subjected to an appearance evaluation test using ultraviolet light irradiation.

[0069] As the main polyol of the coating composition in Table 1, a polyester polyol with a weight average molecular weight (Mw) of 28,000 was used. This was synthesized by the following method. In a reaction apparatus equipped with a reflux condenser, a dropping funnel, a gas inlet tube, and a thermometer, 140 parts by mass of trimethylolpropane, 95 parts by mass of ethylene glycol, 157 parts by mass of adipic acid, and 58 parts by mass of 1,4-cyclohexanedimethanol were charged, and the temperature was raised to 200 to 240°C while stirring, and the mixture was heated (reacted) for 5 hours. After that, a polyester polyol with an acid value of 4, a hydroxyl value of 170, and a weight average molecular weight (Mw) of 28,000 was obtained.

[0070] As the curing agent isocyanate, a nurate (isocyanurate) of hexamethylene diisocyanate (HMDI) available under the trade name Duranate TPA-100 (NCO content 23.1%, non-volatile content 100%) manufactured by Asahi Kasei Corporation was used.

[0071] As the fluorescent material, Hakkol 1800 in Table 1 is a product name PY1800 manufactured by Hakko Chemical Co., Ltd. Curcumin was used under the product name Turmeric Powder sold by Otsuya Shoten. Spirulina was used as a commercially available food coloring (powder type) blue. The fluorescent material was mixed into the base agent. Butyl acetate and water were used as solvents for the base agent and hardener. In addition, the dissolution of the fluorescent material in the solvent was observed and evaluated. Those that dissolved without leaving any precipitate were evaluated as ◎, and those that dissolved mostly but with some precipitate were evaluated as ◯. The evaluation results for the examples and comparative examples are shown in Table 1.

[0072] The covers of all the golf balls were made of ether-type thermoplastic polyurethane (trade name: Pandex) manufactured by DIC Covestro Polymer Co., Ltd. The material hardness of the covers was 47 on the Shore D scale.

[0073] The intermediate layer of each golf ball was formulated with 35 parts by weight of Himilan 1706 (trade name), an ionomer resin made of an ethylene-methacrylic acid copolymer manufactured by Dow Mitsui Polychemicals, 15 parts by weight of Himilan 1557 (trade name), 50 parts by weight of Himilan 1605 (trade name), and 1.1 parts by weight of trimethylolpropane.

[0074] The core of each golf ball was formulated as follows: 20 parts by weight of polybutadiene (product name BR51, manufactured by JSR Corporation) as a base rubber, 80 parts by weight of polybutadiene (product name BR-01, manufactured by JSR Corporation), 28.5 parts by weight of zinc acrylate (manufactured by Wako Pure Chemical Industries Co., Ltd.), 1.0 part by weight of dicumyl peroxide (product name Percumyl D, manufactured by Nippon Oil & Fats Corporation) as an organic peroxide, 0.1 part by weight of 2,2-methylenebis(4-methyl-6-butylphenol) (product name Nocrac NS-6, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) as an antioxidant, 33.0 parts by weight of barium sulfate (product name Precipitated Barium Sulfate #100, manufactured by Sakai Chemical Industry Co., Ltd.), 4.0 parts by weight of zinc oxide (product name Three-type Zinc Oxide, manufactured by Sakai Chemical Industry Co., Ltd.), and 0.5 part by weight of pentachlorothiophenol zinc salt (manufactured by Wako Pure Chemical Industries Co., Ltd.) as an organic sulfur compound.

[0075] [Appearance evaluation test] The appearance of the golf ball when irradiated with ultraviolet light (400 nm UV light) was visually observed, and the luminescence state was evaluated. The evaluation criteria were as follows: when a noticeable luminescence was observed, it was evaluated as ⊚; when sufficient luminescence was observed, it was evaluated as ◯; and when almost no luminescence was observed, it was evaluated as ×. The evaluation results for Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1. The golf balls on which luminescence was observed when irradiated with ultraviolet light emit sufficient light not only on sunny days but also on cloudy days when played outdoors, and have excellent appearance. On the other hand, the golf balls on which luminescence was not observed look yellowish, especially on cloudy days, and have poor appearance. Furthermore, the golf balls on which luminescence was observed can measure the thickness of the cover or top coat containing the fluorescent material with high accuracy even in a golf ball film thickness measurement test using a fluorescent whitening agent. Therefore, the state of the coating of the coating can be well understood, and high-quality golf balls with even coating can be stably provided.

[0076] [Table 1]

[0077] As shown in Table 1, in Comparative Example 1, which did not contain any fluorescent material, almost no luminescence was observed when irradiated with ultraviolet light. On the other hand, in Comparative Example 2, which used the petroleum-derived Hakkol 1800 as the fluorescent material, noticeable luminescence was observed even with the small amount of 0.5 parts by mass.

[0078] In Examples 1 to 3, which used curcumin, a plant-derived extract, luminescence was observed when irradiated with ultraviolet light at any concentration. In particular, the more curcumin was added, the stronger the luminescence became, and it was possible to obtain the same effect as a petroleum-derived fluorescent material. However, it was found that if the amount of curcumin was too high, it did not completely dissolve in the solvent.

[0079] In addition, in Examples 4 and 5, which used spirulina containing an extract derived from algae, luminescence was observed when irradiated with ultraviolet light at any concentration. In Examples 4 and 5, water was used as the solvent for the main agent, but a uniform top coat could be formed as in Examples 1 to 3.

Claims

1. A resin for a cover or top coat of a golf ball; A plant or algae-derived extract that uses light as an energy source to emit light A resin composition for a cover or top coat of a golf ball, comprising: The resin composition for a cover or top coat of a golf ball includes a urethane paint containing a base agent and a curing agent, and the content of the plant- or algae-derived extract is within a range of 0.01 to 5.0 mass % based on the total amount of the base agent including the solvent.

2. 2. The resin composition for a cover or top coat of a golf ball according to claim 1, wherein the solvent is an ester-based solvent or a ketone-based solvent.

3. 2. The resin composition for a cover or top coat of a golf ball according to claim 1, wherein the plant or algae-derived extract is curcumin, ferulic acid, a ferulic acid compound, spirulina, anthocyanin, quinine, phycocyanin, chlorophyll, or a combination thereof.

4. 2. The resin composition for a cover or top coat of a golf ball according to claim 1, wherein the plant or algae-derived extract has an absorbance peak at a wavelength between 350 nm and 450 nm.

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