JP2012110697A - Golf ball - Google Patents

Abstract

(A) Base rubber containing polybutadiene containing 60% by mass or more of cis-1,4-bond, (B) unsaturated carboxylic acid and / or metal salt thereof, (C) organic sulfur compound, D) One or more organic peroxides selected from the group consisting of peroxyketals and / or dialkyl peroxides; (E) One or more types selected from the group consisting of hydroperoxides A golf ball having a cross-linked molded product of a rubber composition containing an organic peroxide as a constituent, and a value obtained by subtracting the center hardness from the surface hardness of the cross-linked molded product is 20 or more in terms of JIS-C hardness.
[Effect] It is possible to reduce the amount of spin in a driver shot, to obtain a certain trajectory that does not feel like dropping or to blow up, and to further increase the flight distance.
[Selection figure] None

Description

  The present invention relates to a solid golf ball. More specifically, the present invention relates to a golf ball in which a spin amount at the time of hitting a driver is reduced and a flight distance is improved.

  The main performances required for golf balls include flight distance, controllability, durability, feel (feel), etc., and the highest performance is always required. Under such circumstances, in recent golf balls, multi-layered balls represented by three pieces are being produced one after another. By making the structure of the golf ball multi-layered, it becomes possible to combine many materials having different characteristics, and by assigning functions to each layer, a wide variety of ball designs are possible.

  In particular, a solid core located at the center of a golf ball (hereinafter sometimes simply referred to as “core”) usually occupies most of the volume of the golf ball, and its characteristics have an effect on the performance of the entire ball. large. Therefore, improving the core characteristics leads to a significant improvement in ball performance.

  Under such circumstances, Japanese Patent Laid-Open No. 2001-259080 (Patent Document 1) describes a ball at the time of hitting a driver by setting a value obtained by subtracting the center hardness from the surface hardness of the core to 20 or more in JIS-C hardness. An invention relating to a two-piece solid golf ball in which the spin amount is reduced to improve the flight distance is disclosed. However, in the present invention, sulfur is added to the rubber composition. As a result, there is a drawback that the crosslinking rate is lowered and the productivity is lowered.

  In addition, for a manufacturer that produces golf balls in large quantities, it is necessary to ensure that all products have good and uniform quality, and it is very important to ensure that the core quality is good and uniform. Therefore, a measure for ensuring that the hardness difference between the center of the core and the surface is JIS-C hardness of 20 or more is desired.

JP 2001-259080 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a golf ball that can reduce the amount of spin when hit by a driver and has excellent flight performance.

  As a result of earnest studies to achieve the above object, the inventor has formulated a rubber composition that forms a core of a one-piece solid golf ball or a solid golf ball having one or two or more covers. In addition to an organic peroxide selected from the group consisting of a base rubber containing a specific polybutadiene, an organic sulfur compound, an unsaturated carboxylic acid and / or a metal salt thereof, a peroxyketal and / or a dialkyl peroxide The value obtained by subtracting the center hardness from the surface hardness is JIS-C hardness without reducing the productivity by adopting the hydroperoxide of an organic compound that has not been used as a crosslinking agent for rubber. It was found that a cross-linked molded product having a value of 20 or more can be obtained easily and reliably. In addition, a one-piece solid golf ball manufactured using the cross-linked molded product and a solid golf ball having a cover of one layer or two or more layers can reduce the spin amount at the time of driver hitting, and the flying performance is improved. This has been found and the present invention has been made.

Accordingly, the present invention provides the following golf balls.
[1] The following components (A) to (E),
(A) a base rubber containing polybutadiene containing 60% by mass or more of cis-1,4-bonds,
(B) an unsaturated carboxylic acid and / or a metal salt thereof,
(C) an organic sulfur compound,
(D) one or more organic peroxides selected from the group consisting of peroxyketals and / or dialkyl peroxides,
(E) A crosslinked molded product of a rubber composition containing one or more organic peroxides selected from the group consisting of hydroperoxides as a constituent element, and the central hardness from the surface hardness of the crosslinked molded product A golf ball characterized by having a value drawn by JIS-C hardness of 20 or more.
[2] The peroxyketal of the component (D) is 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1 -Di (t-butylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 2,2-di (t-butylperoxy) butane, n-butyl 4,4-di- ( [1] The golf ball of [1], which is one or more selected from the group consisting of t-butylperoxy) valate and 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane .
[3] The dialkyl peroxide as the component (D) is di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, Selected from the group consisting of t-butylcumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 The golf ball according to [1] or [2], which is one type or two or more types.
[4] Hydroperoxide of component (E) is p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl The golf ball according to any one of [1] to [3], which is one or more selected from the group consisting of hydroperoxides.
[5] With respect to 100 parts by mass of the component (A), the rubber composition is 10 to 60 parts by mass of the component (B), 0.1 to 5 parts by mass of the component (C), and (D The golf ball according to any one of [1] to [4], comprising 0.25 to 8 parts by mass of a component) and 0.05 to 5 parts by mass of the component (E).

  The golf ball of the present invention can reduce the amount of spin on a driver shot, can obtain a reliable trajectory that does not feel drop or blow up, and can further increase the flight distance Is.

It is a schematic sectional drawing of the golf ball of Examples 10 and 11 of the present invention.

  Hereinafter, the present invention will be described in more detail. The golf ball of the present invention includes a one-piece solid golf ball formed using a specific rubber composition described later, and a cover of one layer or two or more layers around a solid core formed using the rubber composition. A solid golf ball formed.

  The internal structure of the golf ball of the present invention is only required to use a cross-linked molded product having a specific hardness difference using the above rubber composition, and can be set as appropriate without departing from the object of the present invention. There is no particular limitation. For example, in the case of a three-piece solid golf ball having two layers of an inner layer and an outer layer, a core 1, an inner layer cover (intermediate layer) 2 covering the core 1, and the inner layer cover 2 are provided as shown in FIG. It has a three-layer structure including an outer layer cover 3 for covering. In the case where the ball has a multilayer structure having two or more layers of covers, in the present invention, all layers may be collectively referred to as “covers”. A large number of dimples D are usually formed on the surface of the outer cover 3. In FIG. 1, the three-piece solid golf ball G including the core 1, the inner layer cover 2, and the outer layer cover 3 is shown. However, as described above, the configuration can be appropriately changed without departing from the object of the present invention. it can. For example, a one-piece solid golf ball is formed using the above-mentioned crosslinked molded product itself (in this case, a large number of the above dimples D are formed on the surface of the crosslinked molded product), or a single layer cover is formed. It is optional to make a two-piece solid golf ball, and to form a golf ball having a multilayer structure of four or more layers by forming three or more covers. Further, the core 1 can be formed in a plurality of layers.

Here, the golf ball includes the following components (A) to (E),
(A) a base rubber containing polybutadiene containing 60% by mass or more of cis-1,4-bonds,
(B) an unsaturated carboxylic acid and / or a metal salt thereof,
(C) an organic sulfur compound,
(D) one or more organic peroxides selected from the group consisting of peroxyketals and / or dialkyl peroxides,
(E) A crosslinked molded product of a rubber composition containing one or more organic peroxides selected from the group consisting of hydroperoxides is formed as a constituent element.

  As the base rubber of the component (A), polybutadiene can be suitably used. Particularly, the polymer chain has a cis-1,4-bond of 60% by mass or more, preferably 80% by mass or more, more preferably 90%. It is recommended to use at least 95% by weight, most preferably 95% by weight or more. If there are too few cis-1,4-bonds in the bonds in the molecule, the resilience may decrease.

  Further, the content of 1,2-vinyl bond contained in the polybutadiene is preferably 2% or less, more preferably 1.7% or less, and further preferably 1.5% or less in the polymer chain. If the content of 1,2-vinyl bond is too large, the resilience may be lowered.

  In addition to the polybutadiene, other rubber components can be added to the component (A) as long as the effects of the present invention are not impaired. Examples of the rubber component other than the polybutadiene include polybutadiene other than the polybutadiene, and other diene rubbers such as styrene butadiene rubber, natural rubber, isoprene rubber, and ethylene propylene diene rubber.

  The unsaturated carboxylic acid and the metal salt of unsaturated carboxylic acid as component (B) are blended as a co-crosslinking agent.

  Although it does not specifically limit as unsaturated carboxylic acid, For example, acrylic acid, methacrylic acid, maleic acid, fumaric acid etc. can be mentioned, Especially acrylic acid and methacrylic acid are used suitably.

  Although it does not specifically limit as a metal salt of unsaturated carboxylic acid, For example, what neutralized the said unsaturated carboxylic acid with the desired metal ion is mentioned. Specific examples include zinc salts such as methacrylic acid and acrylic acid, magnesium salts, and the like. In particular, zinc acrylate is preferably used.

  The blending amount of the component (B) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more with respect to 100 parts by mass of the base rubber. Moreover, the upper limit of the compounding amount is preferably 60 parts by mass or less, more preferably 45 parts by mass or less, with respect to 100 parts by mass of the base rubber. If the blending amount is too large, it may become too hard and unbearable feel may occur, and if the blending amount is too small, the resilience may decrease.

  The organic sulfur compound of component (C) is added to improve the resilience of the golf ball and increase the initial velocity of the golf ball. The organic sulfur compound is not particularly limited as long as it can improve the resilience of the golf ball, and examples thereof include thiophenols, thionaphthols, halogenated thiophenols, and metal salts thereof. More specifically, pentachlorothiophenol, pentafluorothiophenol, pentabromothiophenol, parachlorothiophenol, zinc salt of pentachlorothiophenol, zinc salt of pentafluorothiophenol, zinc salt of pentabromothiophenol, Examples include zinc salt of parachlorothiophenol, diphenyl polysulfide having 2 to 4 sulfur atoms, dibenzyl polysulfide, dibenzoyl polysulfide, dibenzothiazoyl polysulfide, dithiobenzoyl polysulfide and the like, and particularly preferred is a zinc salt of pentachlorothiophenol. Used.

  The blending amount of the component (C) is preferably 0.1 parts by mass or more, more preferably 0.4 parts by mass or more with respect to 100 parts by mass of the base rubber. Further, the upper limit of the amount is preferably 5 parts by mass or less, preferably 3 parts by mass or less, with respect to 100 parts by mass of the base rubber. If the blending amount is too small, a sufficient resilience improving effect may not be obtained. If the blending amount is too large, the effect of improving the resilience (particularly, the impact by W # 1) cannot be expected any more. In some cases, the core becomes too soft or the feeling of hitting becomes worse.

  Component (D) is an organic peroxide selected from the group consisting of peroxyketals and / or dialkyl peroxides, and is blended in the rubber composition as a crosslinking agent.

  First, examples of the peroxyketal include 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-di ( t-butylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 2,2-di (t-butylperoxy) butane, n-butyl 4,4-di- (t-butyl) Peroxy) valate and 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane and the like, particularly 1,1-di (t-hexylperoxy) cyclohexane is preferably used. Can do. These may be used alone or in combination of two or more, and may be further combined with a dialkyl peroxide described later.

  As the peroxyketal, commercially available products can be used. For example, perhexa HC, perhexa TMH, perhexa C, perhexa V, perhexa 22, perhexa MC, and pertetra A (manufactured by NOF Corporation) are preferably used. it can.

  Next, examples of the dialkyl peroxide include di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t- And butyl cumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide and 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3. Milperoxide can be preferably used. These may be used alone or in combination of two or more, and may be further combined with the above peroxyketal.

  Moreover, as said dialkyl peroxide, a commercial item can be used, for example, park mill D, perhexa 25B, perbutyl P (peroximon F-40), perbutyl C, perhexyl D, perbutyl D, perhexine 25B (made by NOF Corporation). Etc.) can be preferably used.

  The blending amount of the component (D) is preferably 0.25 parts by mass or more, more preferably 0.3 parts by mass or more with respect to 100 parts by mass of the base rubber. Further, the upper limit of the blending amount is preferably 8 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the base rubber. If the blending amount is too large, the durability of the crosslinked molded product may deteriorate, and if the blending amount is too small, a crosslinked molded product having a desired hardness may not be obtained. In addition, when using said peroxyketal and dialkyl peroxide together, what is necessary is just to make the total amount into the said range, and there is no restriction | limiting in particular also about the compounding ratio of both.

  (E) component is 1 type, or 2 or more types of organic peroxide selected from hydroperoxide, and is mix | blended as a crosslinking agent of a rubber composition similarly to the said (D) component. In addition, this (E) component has not been used as a crosslinking agent for rubber until now. In this invention, this (E) component is mix | blended in combination with the said (C) component and (D) component, The value which subtracted center hardness from the surface hardness of the bridge | crosslinking molding is 20 in JIS-C hardness. The effects described above can be obtained.

  Examples of the hydroperoxide include p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, and the like. In particular, p-menthane hydroperoxide and diisopropylbenzene hydroperoxide can be preferably used. These may be used alone or in combination of two or more.

  Moreover, a commercial item can be used as said hydroperoxide, For example, perbutyl H, park mill H, park mill P, permenta H, per octa H (all are NOF Corporation) etc. can be used conveniently.

  The amount of the component (E) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more with respect to 100 parts by mass of the base rubber. Further, the upper limit of the blending amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less with respect to 100 parts by mass of the base rubber. If the blending amount is too large, an effect commensurate with the blending amount may not be obtained, and if the blending amount is too small, the intended effect may not be obtained.

  Various additives can be blended in the rubber composition as necessary, and for example, sulfur, an inert filler, an anti-aging agent, zinc stearate and the like can be blended.

  As the inert filler, for example, zinc oxide, barium sulfate, calcium carbonate and the like can be suitably used. These may be used individually by 1 type and may use 2 or more types together.

  The compounding amount of the inert filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more with respect to 100 parts by mass of the base rubber. Further, the upper limit of blending is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, and still more preferably 100 parts by mass or less with respect to 100 parts by mass of the base rubber. If the blending amount is too large or too small, it may not be possible to obtain an appropriate mass and suitable resilience.

  A known anti-aging agent can be used, and is not particularly limited. Specifically, commercially available products are NOCRACK NS-6 and NS-30 (manufactured by Ouchi Shinsei Chemical Co., Ltd.). And Yoshinox 425 (manufactured by Yoshitomi Pharmaceutical Co., Ltd.). These may be used individually by 1 type and may use 2 or more types together.

  The blending amount of the anti-aging agent can be more than 0, and is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more with respect to 100 parts by mass of the base rubber. The upper limit of the blending amount is not particularly limited, but is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1 part by mass or less, and most preferably 0.5 parts with respect to 100 parts by mass of the base rubber. It can be below mass parts. If the amount is too large or too small, it may not be possible to obtain suitable resilience and durability.

  Said rubber composition can be obtained by kneading said each component using a normal kneading machine (For example, a Banbury mixer, a kneader, a roll, etc.). When a one-piece solid golf ball or a solid golf ball having one or more layers of cover is produced using this rubber composition, a normal molding method such as injection molding or compression molding may be employed. In this case, normal conditions can be adopted as vulcanization conditions, and they can be appropriately set according to the size of the crosslinked molded product, the amount of deflection, and the like. The vulcanization is usually a one-stage vulcanization, but may be a method of vulcanizing in two steps (two-stage vulcanization), and there is no particular limitation.

  In the present invention, the diameter of the cross-linked molded product (one-piece solid golf ball and the core of the solid golf ball having one or two or more covers) formed using the rubber composition is particularly limited. It is not a thing but is suitably set by the structure of the ball.

  The hardness of the crosslinked molded product requires that the difference in hardness between the center hardness and the surface hardness is specified. Specifically, the value obtained by subtracting the center hardness from the surface hardness of the crosslinked molded product needs to be 20 or more in terms of JIS-C hardness. If the hardness difference is small, the spin rate becomes too large and the flight distance performance is degraded. The upper limit of the hardness difference is preferably 40 or less, and particularly preferably 35 or less. If the hardness difference is too large, the resilience of the entire golf ball tends to decrease, and the repeated hitting durability may deteriorate.

  Further, the center hardness of the crosslinked molded product is not particularly limited, but it is recommended that the JIS-C hardness is preferably 40 or more, more preferably 43 or more. On the other hand, the upper limit is not particularly limited, but is preferably 80 or less, more preferably 75 or less.

  The surface hardness of the crosslinked molded product is not particularly limited, but it is recommended that the surface hardness is preferably 60 or more, more preferably 63 or more in terms of JIS-C hardness. The upper limit is not particularly limited, but is preferably 95 or less, more preferably 93 or less.

  Further, the amount of deflection when the cross-linked molded product is loaded, that is, from the state where an initial load of 98 N (10 kgf) is applied to the cross-linked molded product until the final load of 1,275 N (130 kgf) is applied. The amount of deflection (mm) is not particularly limited, but is preferably 2 mm or more, more preferably 2.5 mm or more. The upper limit is not particularly limited, but it is recommended that the upper limit is preferably 6 mm or less, more preferably 5.8 mm or less. If the amount of deflection is small, it is too hard and the hit feeling becomes hard, and the spin amount at the time of hitting the driver increases, which may cause a decrease in flight distance. Conversely, if the amount of deflection is too large, sufficient resilience cannot be obtained, and the flight distance may decrease.

  When a cover is formed on the cross-linked molded product to form a solid golf ball having one or more layers, the cover can be formed of a known material. More specifically, ionomer resins, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and mixtures thereof can be used. Commercially available products may be used for these materials, such as Himiran (Ionomer resin made by Mitsui DuPont Polychemical), Surlyn (Ionomer resin made by DuPont, USA), Iotech (Ionomer resin made by Exxon) and the like. be able to.

  In addition, various additives, such as a ultraviolet absorber, antioxidant, a metal soap, a pigment, and an inorganic filler, can be suitably mix | blended with the said cover material.

  The above cover can be formed by a known method, and injection molding, compression molding, or the like can be employed. For example, when forming a cover by injection molding, a solid core prepared using the above rubber composition is set in a mold for forming the cover in advance, and a cover material is injected into the mold according to a conventional method. What is necessary is just to introduce. As another method, a pair of half cups is molded in advance using the cover material described above, and the core is wrapped with the half cups, and compression-molded, for example, at 120 to 170 ° C. for 1 to 5 minutes. Can also be used.

  When the cover is formed in the present invention, the thickness is not particularly limited, but is preferably 0.2 mm or more, more preferably 0.4 mm or more. The upper limit is not particularly limited. In addition, when the cover is a plurality of layers of two or more layers, the total thickness of all the layers may be set within the above range.

  In the present invention, the amount of deflection of the golf ball on which the cover is formed is not particularly limited, but is preferably 2 mm or more, more preferably 2.2 mm or more. Also, the upper limit of the deflection amount is not particularly limited, but it is recommended that it is preferably 6 mm or less, more preferably 5.5 mm or less. The amount of deflection when a one-piece solid golf ball is formed without forming a cover is not particularly limited, but is preferably the same as the amount of deflection of the golf ball with the cover.

  In the golf ball of the present invention, although not particularly limited, in order to further improve the aerodynamic characteristics and improve the flight distance, it is possible to form a large number of dimples on the surface thereof as in the case of a normal golf ball. it can. By optimizing the kind and total number of the dimples, the trajectory is more stable and the flight performance is excellent. In order to improve the design and durability of the golf ball, the surface of the one-piece solid golf ball or the cover surface of the solid golf ball having one or two or more covers such as ground treatment, stamping, painting, etc. It is also optional to perform the process.

  The golf ball of the present invention can be used in competition and comply with the golf rules. It is preferable that the ball outer diameter is 42.67 mm or more and the weight is 45.93 g or less.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Examples 1-9, Comparative Examples 1-8]
Formation of Core After preparing a rubber composition having the composition shown in Table 1, a core having a diameter of 37.3 mm was prepared by vulcanization molding at 155 ° C. for 20 minutes.

Details of the materials described in Table 1 are as follows.
Polybutadiene: trade name “BR730”, zinc acrylate manufactured by JSR: zinc acrylate is 85% by mass and stearic acid is 15% by mass.
Organic sulfur compound: Zinc salt of pentachlorothiophenol (ZnPCTP)
Inorganic sulfur compound: Manganese sulfate zinc oxide: ZnO Three types of anti-aging agents: 2,2′-methylene-bis (4-methyl-6-tert-butylphenol), trade name “NOCRACK NS-6”, Ouchi Shinsei Chemical Industry Peroxyketal manufactured by the company: 1,1-di (t-butylperoxy) cyclohexane, trade name “Perhexa C-40”, dialkyl peroxide manufactured by NOF Corporation: Dicumyl peroxide, trade name “Park Mill D”, NOF Hydroperoxide (1): p-menthane hydroperoxide, trade name “Permenta H”, Hydroperoxide (2): diisopropylbenzene hydroperoxide, trade name “Park Mill P”, NOF Corporation Made

  About each core obtained above, various physical properties, such as JIS-C hardness of each part and a deflection amount, were evaluated by the test method mentioned later. The results are shown in Table 1. All the above physical properties were measured in an environment of 23 ° C. In addition, since it is clear from Examples 10 and 11 to be described later that the difference in hardness between the center hardness of the core and the surface hardness satisfies the provisions of the present application, the amount of spin is apparent. It is sufficient if the hardness difference between the surface hardness and the surface hardness is measured.

[Examples 10 and 11, Comparative Examples 9 and 10]
Formation of Core After preparing a rubber composition having the composition shown in Table 2, a core having a diameter of 37.3 mm was prepared by vulcanization molding at 155 ° C. for 20 minutes. The materials described in Table 2 are the same as those described in Table 1 above.

Formation of intermediate layer and cover Next, an intermediate layer is formed around the core obtained above by first injection-molding an intermediate layer material having the following composition. The cover material having the composition shown was injection molded to form a cover to obtain a three-piece solid golf ball. In addition, the material for a cover prepared the thing (i) which uniformly mixed and pelletized polyurethane (i-1) and (i-2), and the thing (ii) which pelletized the isocyanate mixture first. Thereafter, a dry blend of the above (i) and (ii) was provided to an injection molding machine.

Material for intermediate layer Formulation High Milan 1605 70 parts by weight Dynalon 6100P 30 parts by weight Behenic acid 20 parts by weight Polytail H 2 parts by weight Calcium hydroxide 3 parts by weight

Details of the above materials are as follows.
High Milan 1605: Ionomer resin, Dynalon 6100P manufactured by Mitsui DuPont Polychemical Co., Ltd .: Hydrogenated polymer, Behenic acid manufactured by JSR Co., Ltd .: Polytail manufactured by NOF Co., Ltd .: Low molecular weight polyolefin polyol, Calcium hydroxide manufactured by Mitsubishi Chemical Co., Ltd. Made

Material for cover Formulation (i) Polyurethane (i-1) 75 parts by mass of Pandex T8295 (i-2) 25 parts by mass of Pandex T8290 (ii) 20 parts by mass of isocyanate mixture

Details of the above materials are as follows.
Pandex T8295:
MDI-PTMG type thermoplastic polyurethane material, resin hardness JIS-A97, rebound resilience 44%, DIC Bayer Polymer Pandex T8290:
MDI-PTMG type thermoplastic polyurethane material, resin hardness JIS-A93, rebound resilience 52%, isocyanate mixture manufactured by DIC Bayer Polymer Ltd .:
Masterbatch containing 30% by mass of 4,4′-diphenylmethane diisocyanate (the base resin of the masterbatch is a polyester elastomer), trade name “Crosnate EM-30”, manufactured by Dainichi Seika Kogyo Co., Ltd.

  For each of the obtained golf balls, various physical properties such as thickness, hardness and deflection amount of each layer and flying performance were evaluated by the following methods. The results are shown in Table 3. All the above physical properties were measured in an environment of 23 ° C.

(1) Deflection amount of core or ball (mm)
The core or the ball was placed on a hard plate, and the amount of deformation from when the initial load of 98 N (10 kgf) was applied to when the final load of 1,275 N (130 kgf) was applied was measured.
(2) Core surface hardness The surface of the core is a spherical surface. Set the surface of the hardness meter so that it is almost perpendicular to the spherical surface, and the surface of the core in accordance with JIS-C hardness (JIS-K6301 standard). The average value of the values measured randomly at two points.
(3) Core hardness The core is cut in half to make a flat surface, and the hardness meter needle is set to be almost vertical at the center, and measured according to JIS-C hardness (JIS-K6301 standard). did.
(4) Ball flying performance A golf striking robot equipped with a driver (W # 1), Bridgestone Sports, “Tour Stage X-DRIVE 701” (shaft flex: X, loft angle: 9.5 °), head speed (HS) The flight distance when hitting at 50 m / s was measured. Similarly, the spin rate was measured with an initial condition measuring device for the ball immediately after hitting.

1 Core 2 Inner layer cover (intermediate layer)
3 Outer layer cover D Dimple G Golf ball

Claims (5)

The following components (A) to (E),
(A) a base rubber containing polybutadiene containing 60% by mass or more of cis-1,4-bonds,
(B) an unsaturated carboxylic acid and / or a metal salt thereof,
(C) an organic sulfur compound,
(D) one or more organic peroxides selected from the group consisting of peroxyketals and / or dialkyl peroxides,
(E) A crosslinked molded product of a rubber composition containing one or more organic peroxides selected from the group consisting of hydroperoxides as a constituent element, and the central hardness from the surface hardness of the crosslinked molded product A golf ball characterized by having a value drawn by JIS-C hardness of 20 or more.   The peroxyketal of the component (D) is 1,1-di (t-hexylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-di ( t-butylperoxy) cyclohexane, 1,1-di (t-butylperoxy) -2-methylcyclohexane, 2,2-di (t-butylperoxy) butane, n-butyl 4,4-di- (t-butyl) The golf ball according to claim 1, wherein the golf ball is one or more selected from the group consisting of peroxy) valate and 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane.   The dialkyl peroxide as the component (D) is di (2-t-butylperoxyisopropyl) benzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butyl. One selected from the group consisting of cumyl peroxide, di-t-hexyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, or The golf ball according to claim 1, wherein there are two or more kinds.   Hydroperoxide of component (E) is p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide The golf ball according to claim 1, wherein the golf ball is one or more selected from the group consisting of:   The said rubber composition is 10-60 mass parts of said (B) component with respect to 100 mass parts of said (A) component, 0.1-5 mass parts of said (C) component, and said (D) component. The golf ball according to any one of claims 1 to 4, wherein 0.25 to 8 parts by mass and 0.05 to 5 parts by mass of the component (E) are blended.

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