golf ball

Abstract

The present invention aims to provide a golf ball that incorporates environmentally friendly materials into its components and maintains good ball performance in the same way as conventional ball products made from petroleum-derived plastic materials. [Solution] The present invention provides a golf ball comprising a core and a cover, wherein the cover is formed mainly of polyurethane, the polyurethane contains bio-based carbon measured according to ISO 16620-2 standard, and the mass ratio of the biomass material containing the bio-based carbon to the total amount of the cover is 10 to 45% by mass.

Description

Technical Field

[0001] The present invention relates to a golf ball having a core and a cover, and to a golf ball in which a cover material contains a biomass material made from carbon derived from plants (such as wheat, sugarcane, beet, tubers, corn, etc.).

Background Art

[0002] In recent years, efforts have been made to reduce the use of petroleum-derived plastic materials in order to reduce the environmental impact and the consumption of petroleum, which is a depletable resource. In the field of golf balls, the constituent members of rubber materials and cover materials are formed of plastics made from petroleum, and it is desirable to provide products that consider the environment if possible. As such prior art documents, for example, Patent Document 1 proposes a golf ball using a biodegradable material as a constituent member. Further, Patent Documents 2 to 5 propose golf balls using de-oil-based materials as constituent members.

[0003] However, although the above biodegradable materials and de-oil-based materials are materials that are good for the environment, in practice, when used as part of the material in golf ball products, it has been difficult to achieve the same performance as plastic materials manufactured from existing petroleum.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

[0005] This invention has been made in view of the above circumstances, and aims to provide a golf ball that incorporates environmentally friendly materials as its constituent components and can exhibit performance equivalent to conventional ball products made from petroleum-derived plastic materials. [Means for solving the problem]

[0006] As a result of diligent research to achieve the above objective, the inventors have discovered that, for a golf ball comprising a core and a cover, the cover is formed primarily of polyurethane, and this polyurethane material contains bio-based carbon measured according to ISO 16620-2 standards, and the mass ratio of biomass material is set within the range of 10 to 45%, thereby achieving performance comparable to conventional golf balls made of petroleum-derived plastic materials, leading to the present invention.

[0007] Therefore, the present invention provides the following golf ball. 1. A golf ball comprising a core and a cover, wherein the cover is formed primarily of polyurethane, the polyurethane contains bio-based carbon measured according to ISO 16620-2 standards, and the mass ratio of the biomass material containing the bio-based carbon to the total amount of the cover is 10 to 45% by mass. 2. The golf ball described in item 1 above, wherein the product of the mass ratio of the biomass material and the material hardness (Shore D) in the cover is 470 or more and less than 2010. 3. The above cover consists of the following components (I) and (II). (I) Polyurethane, (II) (meth)acrylic block copolymer A golf ball according to claim 1 or 2 above, formed from a resin composition containing the above. 4. The golf ball according to item 3 above, wherein the amount of component (II) is 20 parts by mass or less per 100 parts by mass of component (I). 5. The golf ball described in item 3 above, wherein the material hardness of component (II) above is 40 or less on the Shore D hardness scale. 6. The golf ball described in item 3 above, wherein the rebound elasticity of component (II) above is 40% or less as measured according to the JIS-K 6255 standard. 7. The golf ball described in item 3 above, wherein the melt flow rate (MFR) value of component (II) above is 20 g / 10 min or more under measurement conditions (ISO1133) of 230°C and a 2.16 kgf load. 8. The golf ball according to item 3 above, wherein in the block copolymer of component (II) above, the hard segment is mainly composed of methyl methacrylate units, and the soft segment is mainly composed of n-butyl acrylate units or n-butyl acrylate / 2-ethylhexyl acrylate units. 9. The golf ball according to item 8 above, wherein the content of methyl methacrylate units in the block copolymer of component (II) above is 20 to 50% by mass. 10. A golf ball as described in item 1 or 2 above, wherein the thickness of the cover is 0.6 to 1.8 mm. [Effects of the Invention]

[0008] The golf ball of the present invention incorporates environmentally friendly materials into its components and can have performance comparable to conventional golf balls made from petroleum-derived plastic materials. [Modes for carrying out the invention]

[0009] The present invention will be described in more detail below. The golf ball of the present invention comprises at least one core layer and at least one cover layer. Each of the above layers will be described in detail below.

[0010] The core can be formed as a single layer or in multiple layers. As the core material, known rubber materials and various resin materials can be used as the base material. When the core is formed from rubber, known base rubbers such as natural rubber or synthetic rubber can be used as the base rubber. More specifically, it is recommended to mainly use polybutadiene, particularly cis-1,4-polybutadiene having at least 40% cis structure. Furthermore, in the base rubber, natural rubber, polyisoprene rubber, styrene-butadiene rubber, etc., can be used in combination with the aforementioned polybutadiene, if desired. Polybutadiene can also be synthesized using Ziegler catalysts such as titanium-based, cobalt-based, nickel-based, and neodymium-based catalysts, as well as metal catalysts such as cobalt and nickel.

[0011] The above-mentioned base rubber can be compounded with co-crosslinking agents such as unsaturated carboxylic acids and their metal salts, 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. Furthermore, commercially available antioxidants may be added as needed.

[0012] The above-mentioned core can be manufactured by heating and curing a rubber composition containing the above-mentioned components. For example, it can be manufactured by kneading using a kneader such as a Banbury mixer or roll, compression molding or injection molding using a core mold, and then curing the molded body by appropriately heating it at a temperature of 100 to 200°C, preferably 140 to 180°C, for 10 to 40 minutes, which is sufficient for the organic peroxide and co-crosslinking agent to act.

[0013] The specific gravity of the above core is not particularly limited, but is preferably 1.00 or more, more preferably 1.03 or more, still more preferably 1.06 or more. As the upper limit, it is preferably 1.20 or less, more preferably 1.17 or less, still more preferably 1.14 or less. In order to ensure good flight distance performance when the driver is hit, it is necessary to make the mass of the ball about 45.0 to 45.6 g. In such a case, if the specific gravity of the core is smaller than the above range, it is necessary to increase the specific gravity of the intermediate layer and the cover layer. Therefore, by adding a specific gravity adjusting material, the spin performance of the ball may be impaired. On the other hand, if the specific gravity of the core is too large, the moment of inertia may become too small and the roll on the putter may deteriorate.

[0014] In the present invention, the cover is formed mainly of polyurethane. In particular, as a resin composition mainly composed of polyurethane, the following components (I) and (II) (I) Polyurethane, (II) (Meth)acrylic block copolymer It is preferable to contain them. Hereinafter, the following components (I) and (II) will be described.

[0015] [(I) Polyurethane] Polyurethane can be the main material or the base resin of the above cover material (resin composition). The details of this component, polyurethane, are as follows.

[0016] The structure of polyurethane consists of a soft segment made of a high molecular weight polyol (polymeric glycol) which is a long-chain polyol, and a chain extender and a polyisocyanate that constitute the hard segment. Here, as the high molecular weight polyol used as a raw material, any of those conventionally used in technologies related to polyurethane materials can be used, and there are no particular restrictions. For example, polyester polyols, polyether polyols, polycarbonate polyols, polyester polycarbonate polyols, polyolefin polyols, conjugated diene polymerization polyols, castor oil polyols, silicone polyols, vinyl polymerization polyols, etc. can be mentioned. As the polyester polyol, specifically, adipate polyols such as polyethylene adipate glycol, polypropylene adipate glycol, polybutadiene adipate glycol, polyhexamethylene adipate glycol, and lactone polyols such as polycaprolactone polyol can be adopted. Examples of polyether polyols include poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol), and poly(methyltetramethylene glycol). These may be used alone or in combination of two or more.

[0017] As the above high molecular weight polyol, it is preferable to use a polyether polyol.

[0018] In this invention, not only conventional petroleum-derived polymer polyols can be used, but also polymer polyols made from carbon derived from biological resources such as plants (wheat, sugarcane, beets, potatoes, corn, etc.). In other words, biomass materials can be used as the polyol component of polyurethane. Biomass is a concept that represents the quantity (mass) of biological resources (bio), and is defined as "renewable, biologically derived organic resources excluding fossil resources." While biodegradable materials have existed as environmentally friendly golf ball materials, they have had difficulty exhibiting performance such as flight performance and durability as existing plastic materials made from petroleum. Therefore, in this invention, by using biomass materials within a predetermined range as a raw material for the polyurethane cover, it is possible to maintain good ball performance and use environmentally friendly materials as golf ball materials.

[0019] Specifically, the polyurethane cover is made from bio-based carbon measured according to ISO 16620-2 standards, and the biomass material used is such that the mass ratio of the biomass material containing the bio-based carbon to the total amount of cover (hereinafter also referred to as the "biomass mass ratio") is within the range of 10 to 45% by mass.

[0020] The above biomass mass ratio (%) is calculated using the following formula. Biomass mass ratio (%) = {(Mass of polyol in resin) × (Mass ratio of biomass-derived polyol in polyol)} / (Total mass of resin)} × 100

[0021] ISO 16620-2 is an international standard for calculating the biomass content of biomass plastics, and it includes radiocarbon ( 14 C) This method uses analysis to detect synthetic substances. Substances derived solely from bio-based sources are considered to be of a certain quality. 14 It has a concentration of C (radiocarbon), and in this case, ISO 16620-2 defines it as 100% bio-based. On the other hand, all substances are petroleum-derived. 14Since it contains no carbon (C), it has a bio-based content of 0%. In other words, bio-based products (extracts from plants, animals, etc.) and petroleum-derived industrial products are indicated as having a bio-based content between 0% and 100% depending on the proportion.

[0022] If the biomass mass ratio falls below 10% by mass, it cannot be said to be an environmentally friendly material. On the other hand, if it exceeds 45% by mass, that is, if the biomass ratio of the cover is too high, it becomes difficult to adjust it to achieve the appropriate performance as a urethane material for golf balls.

[0023] The number-average molecular weight of the above polyol is preferably in the range of 1,000 to 5,000. By using a long-chain polyol having such a number-average molecular weight, it is possible to reliably obtain a golf ball made of a polyurethane composition that is excellent in various properties such as resilience and productivity as described above. The number-average molecular weight of the long-chain polyol is more preferably in the range of 1,500 to 4,000, and even more preferably in the range of 1,700 to 3,500.

[0024] The number-average molecular weight mentioned above is the number-average molecular weight calculated based on the hydroxyl value measured in accordance with JIS-K1557 (the same applies hereinafter).

[0025] As chain extenders, those used in conventional polyurethane technologies can be suitably used and are not particularly limited. In the present invention, low molecular weight compounds having two or more active hydrogen atoms capable of reacting with an isocyanate group and a molecular weight of 2,000 or less can be used, and among these, aliphatic diols having 2 to 12 carbon atoms can be suitably used. Specifically, examples include 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, and among these, 1,4-butylene glycol can be suitably used.

[0026] As for the polyisocyanate, those used in conventional polyurethane technologies can be suitably used, and there are no particular restrictions. Specifically, one or more selected from the group consisting of 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylenediisocyanate, xylylene diisocyanate, naphthylene 1,5-diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, and dimer acid diisocyanate can be used. However, depending on the isocyanate species, it may be difficult to control the crosslinking reaction during injection molding.

[0027] Furthermore, the ratio of active hydrogen atoms to isocyanate groups in the polyurethane formation reaction described above can be adjusted to a suitable range. Specifically, when producing polyurethane by reacting the long-chain polyol, polyisocyanate compound, and chain extender, it is preferable to use each component in a ratio such that the isocyanate groups contained in the polyisocyanate compound are 0.95 to 1.05 moles for every 1 mole of active hydrogen atoms contained in the long-chain polyol and chain extender.

[0028] The method for producing polyurethane is not particularly limited, and it may be produced using a long-chain polyol, a chain extender, and a polyisocyanate compound, utilizing known urethane formation reactions, by either a prepolymer method or a one-shot method. Among these, melt polymerization in the substantially absence of solvent is preferred, and production by continuous melt polymerization using a multi-screw extruder is particularly preferred.

[0029] As the polyurethane mentioned above, it is preferable to use a thermoplastic polyurethane material, and in particular, an ether-based thermoplastic polyurethane material is preferred. Commercially available thermoplastic polyurethane materials can be suitably used, such as "Pandex" manufactured by DIC Covestropolymer Co., Ltd. and "Rezamin" manufactured by Dainichi Seika Kogyo Co., Ltd.

[0030] Regarding the material hardness of component (I) above, from the viewpoint of spin characteristics and scratch resistance obtained as a golf ball, it is preferably 52 or less on the Shore D hardness scale, more preferably 50 or less on the Shore D hardness scale, and even more preferably 48 or less on the Shore D hardness scale. Furthermore, as a lower limit, from the viewpoint of moldability, it is preferably 38 or more on the Shore D hardness scale, and more preferably 40 or more on the Shore D hardness scale.

[0031] The rebound modulus of component (I) described above is preferably 55% or higher, more preferably 57% or higher, and even more preferably 59% or higher, considering the overall performance of the golf ball, including initial velocity and spin performance at impact. The rebound modulus described above is measured in accordance with the JIS-K 6255:2013 standard.

[0032] The above component (I) is the main material of the resin composition, and in order to sufficiently impart the scratch resistance of the urethane resin, it is present in an amount of 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more of the resin composition.

[0033] In this invention, by combining component (I) described above with component (II) described in detail below, the product offers excellent controllability during approach shots, scratch resistance, and moldability.

[0034] [(II)(meth)acrylic block copolymer] In this specification, the term "(meth)acrylic block copolymer" is used to mean both acrylic block copolymers and methacrylic block copolymers.

[0035] The (meth)acrylic block copolymer of component (II) is preferably a block copolymer having two or more blocks constituting a hard segment and one or more blocks constituting a soft segment. That is, the (meth)acrylic block copolymer used in the present invention is a polymer containing block polymers A and B, and can be represented by the chemical structure AB or ABA. Note that the (meth)acrylic block copolymer used in the present invention has a different chemical structure from a general core-shell type acrylic copolymer.

[0036] Block polymer A is a part that constitutes the hard segment, and specific monomer units include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, phenyl methacrylate, and 2-hydroxyethyl methacrylate, with methyl methacrylate (MMA) being the main component. Block polymer A can be composed of one or more of the above monomer units in combination.

[0037] On the other hand, block polymer B is the part that constitutes the soft segment, and specific examples of monomer units include acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, benzyl acrylate, phenoxyethyl acrylate, and 2-methoxyethyl acrylate, with n-butyl acrylate (nBA) being the main component. Block polymer B can be composed of one or more of the above monomer units in combination.

[0038] The glass transition temperature (Tg) of block polymer A, which exhibits a hard segment, is preferably 80 to 140°C, and more preferably 100 to 120°C. On the other hand, the glass transition temperature (Tg) of block polymer B, which exhibits a soft segment, is preferably -80 to -20°C, and more preferably -60 to -40°C.

[0039] In the above (meth)acrylic block copolymer, the content ratio of hard segments to soft segments is preferably 5:95 to 40:60 by mass ratio, and more preferably 10:90 to 30:70. A higher proportion of soft segments can be expected to soften the resin composition and obtain the desired approach control properties, but if the proportion of hard segments is too low, the compatibility with the base material, such as polyurethane resin, will decrease, and moldability may deteriorate.

[0040] When the hard segment is mainly composed of methyl methacrylate units, it is preferable that the content of methyl methacrylate units in the block copolymer of component (II) above be 20 to 50% by mass. If this value is too low, the fluidity becomes too high, making it unsuitable as a molding material. On the other hand, if this value is too high, the resulting molded product may become too hard.

[0041] (Meth)acrylic block copolymers can be obtained by polymerizing the above monomer units, and examples of polymerization methods include radical polymerization, living anion polymerization, and living radical polymerization. Examples of polymerization methods include solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

[0042] The mass-average molecular weight of the (meth)acrylic block copolymer is not particularly limited, but is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 45,000 or more. The upper limit is preferably 200,000 or less, more preferably 150,000 or less, and even more preferably 100,000 or less. The higher the mass-average molecular weight, the lower the rebound effect, the higher the spin rate, and the better the controllability during approach shots. This mass-average molecular weight can be measured by gel permeation chromatography (GPC).

[0043] The (meth)acrylic block copolymer used in the present invention is preferably a polymer in which the hard segment is mainly composed of methyl methacrylate units and the soft segment is mainly composed of n-butyl acrylate units. Commercially available (meth)acrylic block copolymers can be used, for example, Kuraray's "Clarity" series, specifically the product names "Clarity LA2114," "Clarity LA2140," "Clarity LA2250," "Clarity LA2270," "Clarity LA2330," and "Clarity LA4285."

[0044] Regarding the material hardness of component (II) above, from the viewpoint of improving approach spin, it is preferable that the Shore D hardness be 40 or less, more preferably 38 or less, even more preferably 35 or less, and most preferably 32 or less. Furthermore, the lower limit is preferably 7 or more, more preferably 15 or more, and even more preferably 20 or more, in terms of Shore D hardness.

[0045] The rebound modulus of component (II) is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less, in order to maintain approach spin and keep rebound low to obtain controllability. Furthermore, the lower limit of the rebound modulus is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. The rebound modulus is measured in accordance with the JIS-K 6255:2013 standard.

[0046] (II) By setting the melt flow rate (MFR) of component (II) to a high value, the fluidity of the polyurethane resin material can be improved, the molding temperature during molding can be reduced, the severance and degradation of urethane molecules can be suppressed, and scratch resistance can be further improved. Specifically, measured under ISO 1133 standards, test temperature 230°C, and test load 21.18 N (2.16 kgf), it is preferably 2 g / 10 min or more, more preferably 50 g / 10 min or more, even more preferably 100 g / 10 min or more, and most preferably 200 g / 10 min or more.

[0047] The amount of component (II) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of component (I). Exceeding this value may reduce abrasion resistance. The lower limit of the above amount is 0.5 parts by mass or more, preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of component (I).

[0048] The resin composition containing (I) and (II) above may also contain other resin materials in addition to the resin components described above. The purpose of this is to further improve the fluidity, rebound, crack resistance, and other physical properties of the resin composition for golf balls.

[0049] The above resin composition can be obtained, for example, by mixing the above-mentioned components using various kneaders such as a kneading-type (single-screw or) twin-screw extruder, a Banbury, or a kneader.

[0050] The rebound modulus of the above resin composition is required to be 48% or higher, preferably 50% or higher, more preferably 52% or higher, with an upper limit of 72% or lower, preferably 70% or lower, and more preferably 68% or lower, in order to improve low rebound properties and approach spin amount.

[0051] Furthermore, regarding the material hardness of the above resin composition, from the standpoint of scratch resistance and appropriate approach spin, it is preferable that the Shore D hardness be 50 or less, more preferably 48 or less, and even more preferably 45 or less. As a lower limit, from the standpoint of moldability, it is preferable that the Shore D hardness be 30 or more, more preferably 35 or more, and even more preferably 37 or more.

[0052] Furthermore, it is preferable that the product of the mass ratio of biomass material in the above resin composition and the material hardness (Shore D) be between 470 and 2010. For example, if the mass ratio of biomass material is 35% and the material hardness (Shore D) is 43, the product will be "35 × 43 = 1505". If the numerical range deviates from the above range, the material may not be environmentally friendly, or it may have insufficient scratch resistance or approach spin.

[0053] The thickness of the cover formed from the above resin composition is preferably 0.4 mm or more, more preferably 0.5 mm or more, and even more preferably 0.6 mm or more, with an upper limit of preferably 2.0 mm or less, and more preferably 1.8 mm or less. If the cover is too thin, the abrasion resistance of the ball when struck with a wedge may be poor. On the other hand, if the cover is too thick, the ball may spin too much, and the desired distance may not be achieved.

[0054] The hardness of the cover material is not particularly limited, but is preferably 52 or less, more preferably 50 or less, and even more preferably 48 or less on the Shore D hardness scale, with a lower limit of preferably 40 or more, and more preferably 43 or more. Setting the above hardness relatively low makes it difficult for the ball speed to increase during putting, and reduces the variation in putting distance. Furthermore, within the above range, the harder the material, the greater the increase in distance due to reduced spin during full shots with an iron (I#6).

[0055] Furthermore, at least one intermediate layer can be formed between the core and the cover.

[0056] The intermediate layer is preferably formed from a resin composition. Examples of such resin compositions include those primarily composed of resins conventionally used as materials for golf balls. Examples of base resins for the resin composition include ionomer resins, polyester resins, polyurethane resins, polyamide resins, polyolefin resins, olefin-based thermoplastic elastomers, and styrene-based thermoplastic elastomers. In particular, ionomer resins are preferred in terms of resilience and moldability.

[0057] The surface of the cover can typically have one or more types of dimples formed on it, and the shape, diameter, depth, number, and occupied surface area of ​​these dimples are selected as appropriate.

[0058] The method for manufacturing a golf ball is not particularly limited, and it can be obtained by molding using known molding methods such as injection molding and compression molding. For example, a core can be set in the mold of an injection molding machine, and the above-mentioned intermediate layer resin composition can be supplied to produce a coated sphere (intermediate layer coated sphere) with the intermediate layer covering the core. Then, the intermediate layer coated sphere can be set in the mold of another injection molding machine, and a cover resin composition can be injected to produce a golf ball with a cover.

[0059] Furthermore, a paint layer can be formed on the surface of the cover. In this case, the paint layer is formed using a paint composition. There are no particular restrictions on the base resin of this paint composition, but examples include polyurethane resin, epoxy resin, polyester resin, acrylic resin, and cellulose resin. From the viewpoint of durability of the paint layer, it is preferable to use a two-component curable polyurethane resin. In addition, various additives such as antioxidants, ultraviolet absorbers, light stabilizers, fluorescent agents, and fluorescent whitening agents can be added to the paint composition in appropriate amounts as needed.

[0060] There are no particular restrictions on the method of applying the above-mentioned paint to the surface of the cover; known methods can be used, such as electrostatic painting, spray gun painting, or brush painting.

[0061] The specifications of the golf ball of this invention, such as its mass and diameter, can be set appropriately in accordance with the rules of golf. [Examples]

[0062] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0063] [Examples 1-10, Comparative Examples 1-6] Core compositions were prepared using the rubber compound shown in Table 1, which is common to each of the examples and comparative examples, and vulcanized to produce cores with diameters of 38.7 mm and 39.3 mm. Zinc oxide and zinc acrylate were added in appropriate amounts to achieve the desired core specific gravity and deflection, and four types, A, B, C, and D, were prepared.

[0064] [Table 1]

[0065] Details regarding the above formulation are as follows: • Polybutadiene: Product name "BR 01" (manufactured by ENEOS Material Co., Ltd.) • Organic peroxide: Dicumyl peroxide, trade name "Perkmyl D" (manufactured by NOF Corporation) • Zinc oxide: Product name "Zinc Oxide 3 Types" (manufactured by Sakai Chemical Industry Co., Ltd.) • Zinc acrylate: Product name "ZN-DA85S" (manufactured by Nippon Shokubai Co., Ltd.)

[0066] [Formation of the intermediate layer and cover (outermost layer)] Next, for each example and comparative example, using the injection molding die described below, an intermediate layer with a thickness of 1.20 mm and a Shore D hardness of 66 to 68 is formed around the core surface using the intermediate layer resin materials E to G shown in Table 2.

[0067] [Table 2]

[0068] The details of the ingredients listed in the table above are as follows: • "Hymilan AM7318" is an ionomer resin manufactured by Mitsui Dow Polychemicals. • "Hymirene 1706" is an ionomer resin manufactured by Mitsui Dow Polychemicals. • "Trimethylolpropane" manufactured by Tokyo Chemical Industry Co., Ltd. • "Barium Sulfate" - Sakai Chemical Industry Co., Ltd.'s product name "Precipitated Barium Sulfate 300"

[0069] Next, using a different injection molding die, 16 types of urethane resin compositions C1 to C16 shown in Tables 3 and 4 are injection molded around the intermediate layer-covered sphere to form a cover (outermost layer) with a thickness of 0.8 mm and a Shore D hardness of 43 to 50.

[0070] [Table 3]

[0071] [Table 4]

[0072] The details of the ingredients in the table above are as follows: • "TPU-A" is an ether-type thermoplastic polyurethane manufactured by DIC Covestropolymer Co., Ltd. (The polyol component is a mixture of petroleum-based polyol A and bio-polyol A in predetermined ratios.) • "TPU-B" is an ether-type thermoplastic polyurethane manufactured by DIC Covestropolymer Co., Ltd. (Cover formulations C2-C5, C13: The polyol component is a mixture of petroleum-based Polypol B and Bio-Polyol B in predetermined ratios. Cover formulations C6, C14: The polyol component uses only petroleum-based Polypol B.) • "TPU-C" is an ether-type thermoplastic polyurethane manufactured by DIC Covestropolymer Co., Ltd. (The polyol component is a mixture of petroleum-based polyol C and biopolyol C in predetermined ratios.) • "TPU-D" is an ether-type thermoplastic polyurethane manufactured by DIC Covestropolymer Co., Ltd. (Cover compound C8-C12: The polyol component is a mixture of petroleum-based polyol D and biopolyol D in predetermined ratios.) • "TPU-E" is an ether-type thermoplastic polyurethane manufactured by DIC Covestropolymer Co., Ltd. (Cover formulation C15: The polyol component is a mixture of petroleum-based polypol E and bio-polyol E in predetermined ratios. Cover formulation C16: The polyol component uses only petroleum-based polypol E.) "LA2250" is a (meth)acrylic block copolymer (hard segment PMMA / soft segment PBA) from Kuraray's "Clarity LA" series.

[0073] The biomass mass ratio (%) in the table above is calculated using the following formula. Biomass mass ratio (%) = {(Mass of polyol in resin) × (Mass ratio of biomass-derived polyol in polyol)} / (Total mass of resin)} × 100

[0074] The methods for measuring the core deflection, the material hardness of the intermediate layer, and the material hardness of the cover are as follows.

[0075] [Core deflection amount] The core object is placed on a hard plate, and the deflection is measured when an initial load of 98N (10kgf) is applied and then a final load of 1275N (130kgf) is applied. The deflection values ​​mentioned above were measured in a room at 23.9±2℃ after the core was kept at a constant temperature of 23.9±1℃ for at least 3 hours. A high-load compression tester manufactured by Mu Seiki Co., Ltd. was used as the measuring instrument, and the down speed of the pressure head used to compress the core was set to 10mm / s.

[0076] [Material hardness of the intermediate layer and cover] Each layer of resin material is molded into a 2mm thick sheet and left for two weeks. Afterward, the Shore D hardness is measured according to the ASTM D2240 standard. A P2 automatic rubber hardness tester manufactured by Polymer Instruments Co., Ltd. is used for hardness measurement. A Shore D hardness attachment is fitted, and the hardness of each layer is measured. The maximum value is read. All measurements are performed under conditions of 23±2℃.

[0077] For each of the obtained golf ball samples, the distance traveled with a driver, the spin rate and controllability during approach shots, and the abrasion resistance were evaluated using the following methods. The results are shown in Table 5.

[0078] [Driver distance] Using a swing robot machine, a driver (W#1) will be attached to the robot, and the total distance of the shot will be measured when it is hit at a head speed (HS) of 45 m / s. The club used will be a Bridgestone "TourB XD-5 Driver (Loft 8.5°)" (2017 model).

[0079] [Approach spin rate and controllability] Using a swing robot machine, a sand wedge will be attached to the robot, and the amount of spin will be measured when the ball is struck at a head speed (HS) of 20 m / s. The amount of spin will be measured immediately after impact using an initial condition measurement device. The sand wedge used will be a Bridgestone Sports "TourStage TW-03 (loft angle 57°) 2002 model".

[0080] [Evaluation of abrasion resistance] The balls are kept warm at 23°C, and using a swing robot machine, a pitching wedge (PW) is used to hit each ball five times at a head speed of 33 m / s. The impact damage is then visually evaluated according to the following criteria. ◎ ··· No scratches, or very few scratches. ○... There are some minor scratches, but they are hardly noticeable. △ ··· The surface is slightly fuzzy. × ··· The surface is frayed or the dimples are missing.

[0081] [Table 5]

[0082] As shown in Table 5, the following points should be considered. Comparing Examples 1-4 with Comparative Examples 1 and 2, Examples 1-4, which use biomass materials, achieve similar performance to Comparative Example 2 (petroleum-derived with a biomass mass ratio of 0%). That is, when a biopolyol is used with a biomass mass ratio of 0-45% in the cover resin material, the same performance as Comparative Example 2 can be obtained. On the other hand, in Comparative Example 1, the biomass mass ratio is high at 49%, and as a result, sufficient performance is not obtained. Comparing Examples 5-8 with Comparative Examples 3 and 4, Examples 5-8, which use biomass materials, achieve similar performance to Comparative Example 4 (a conventional petroleum-derived material). That is, when a biopolyol is used with a biomass mass ratio of 0-40% in the cover resin material, the same performance as Comparative Example 4 can be obtained. On the other hand, in Comparative Example 3, the biomass mass ratio was a high 47%, and sufficient performance was not obtained. Comparing Example 9 with Comparative Example 5, Example 9, which uses biomass materials, achieves the same performance as Comparative Example 5 (a conventional petroleum-derived material). Comparing Example 10 with Comparative Example 6, Example 10, which uses biomass materials, achieves the same performance as Comparative Example 6 (a conventional petroleum-derived material).

Claims

1. A golf ball comprising a core and a cover, wherein the cover is formed mainly of polyurethane, the polyurethane contains bio-based carbon measured according to ISO 16620-2 standard, and the mass ratio of the biomass material containing the bio-based carbon to the total amount of the cover is 10 to 45% by mass.

2. The golf ball according to claim 1, wherein the product of the mass ratio of the biomass material and the material hardness (Shore D) in the cover is 470 or more and less than 2010.

3. The above cover consists of the following components (I) and (II). (I) Polyurethane, (II) (meth)acrylic block copolymer A golf ball according to claim 1 or 2, formed from a resin composition containing the above.

4. The golf ball according to claim 3, wherein the amount of component (II) is 20 parts by mass or less per 100 parts by mass of component (I).

5. The golf ball according to claim 3, wherein the material hardness of component (II) above is 40 or less on the Shore D hardness scale.

6. The golf ball according to claim 3, wherein the rebound elasticity of component (II) above is 40% or less as measured according to the JIS-K 6255 standard.

7. The golf ball according to claim 3, wherein the melt flow rate (MFR) value of component (II) above is 20 g / 10 min or more under measurement conditions of 230°C and a 2.16 kgf load (ISO 1133).

8. The golf ball according to claim 3, wherein in the block copolymer of component (II) above, the hard segment is mainly composed of methyl methacrylate units, and the soft segment is mainly composed of n-butyl acrylate units or n-butyl acrylate / 2-ethylhexyl acrylate units.

9. The golf ball according to claim 8, wherein the content of methyl methacrylate units in the block copolymer of component (II) above is 20 to 50% by mass.

10. The golf ball according to claim 1 or 2, wherein the thickness of the cover is 0.6 to 1.8 mm.

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