Rubber composition for grips and golf club grips

Abstract

The present invention provides a rubber composition for grips that yields crosslinked rubber with a high static friction coefficient. [Solution] The rubber composition for grips contains a base rubber, hard porous carbon particles, and a vulcanizing agent, wherein at least a portion of the hard porous carbon particles is composed of glassy carbon, and the content of the hard porous carbon particles is 1.5% to 8.5% by mass of 100% by mass of the rubber composition.

Description

[Technical Field]

[0001] This invention relates to a rubber composition for grips used in the manufacture of grips. [Background technology]

[0002] Rubber grips are widely used as grips (anti-slip components) attached to sports equipment and other items. In such grips, it has been proposed to use hydrogenated carboxy-modified acrylonitrile-butadiene rubber as the base rubber.

[0003] For example, Patent Document 1 describes a grip for sports equipment characterized in that the outermost layer is formed from a surface rubber composition containing (A) a base rubber and (B) a resin having a softening point of 5°C to 120°C, wherein the (A) base rubber contains acrylonitrile-butadiene rubber, and the (B) resin is at least one selected from the group consisting of hydrogenated rosin ester, disproportionated rosin ester, ethylene-vinyl acetate copolymer, coumarone resin, phenolic resin, xylene resin, and styrene resin (see Patent Document 1 (Claim 1, paragraphs 0013, 0019)). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-113388 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Grips used on sports equipment and other items require excellent anti-slip properties. While the anti-slip properties of a grip can be improved by forming a groove pattern on its surface, it is preferable that the cross-linked rubber that makes up the grip itself has a high coefficient of friction. Here, as a method to increase the coefficient of friction of cross-linked rubber, there is a method of adding tackifying low molecular weight components such as rosin or coumarone resin, or liquid softeners, to the rubber composition, as described in Reference 1. However, when the amount of low molecular weight tackifying components or softeners added was large, there was a tendency for bleeding to occur after curing.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a rubber composition for grips that can obtain a crosslinked rubber having a high static friction coefficient. [Means for solving the problem]

[0007] The rubber grip composition of the present invention, which has been able to solve the above problems, contains a base rubber, hard porous carbon particles, and a vulcanizing agent, wherein at least a portion of the hard porous carbon particles is composed of glassy carbon, and the content of the hard porous carbon particles is 1.5% to 8.5% by mass in 100% by mass of the rubber composition.

[0008] By incorporating a predetermined amount of hard, porous carbon particles into the rubber grip composition, these particles become present on the surface of the formed grip. These hard, porous carbon particles on the grip surface exert a microspike effect against the user's gloves or other equipment. Therefore, grips molded using this rubber grip composition have a high coefficient of static friction. [Effects of the Invention]

[0009] The rubber composition for grips of the present invention yields a crosslinked rubber having a high static friction coefficient. Therefore, according to the present invention, a grip can be obtained in which the crosslinked rubber constituting the grip itself has a high static friction coefficient. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing an example of a golf club grip according to the present invention. [Figure 2]It is a perspective view showing an example of a golf club provided with a grip for a golf club of the present invention.

Mode for Carrying Out the Invention

[0011] [Rubber Composition for Grip] The rubber composition for a grip of the present invention (hereinafter, may be simply referred to as "rubber composition") is used for molding a grip. The rubber composition contains a base rubber, hard porous carbon particles, and a vulcanizing agent. At least a part of the hard porous carbon particles is composed of glassy carbon, and the content of the hard porous carbon particles is 1.5% by mass to 8.5% by mass in 100% by mass of the rubber composition.

[0012] By blending a predetermined amount of hard porous carbon particles into the rubber composition for a grip, hard porous carbon particles come to exist on the surface of the formed grip. The hard porous carbon particles present on the surface of this grip exert a micro-spike effect on gloves, etc. of the grip user. Therefore, the grip molded using the rubber composition for a grip has a high static friction coefficient. Further, since the hard porous carbon particles present on the surface of the grip are porous, they can absorb sweat, etc. of the grip user. Therefore, the anti-slip performance during grip use is further improved.

[0013] (Base Rubber) The rubber composition contains a base rubber. The content of the base rubber in the rubber composition is preferably 50% by mass or more, more preferably 55% by mass or more. Examples of the aforementioned base rubbers include diene rubbers such as natural rubber (NR), ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (HNBR), carboxy-modified acrylonitrile-butadiene rubber (XNBR), hydrogenated carboxy-modified acrylonitrile-butadiene rubber (HXNBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), and chloroprene rubber (CR); and non-diene rubbers such as butyl rubber (IIR), ethylene-propylene rubber (EPM), and urethane rubber (PU). These base rubbers may be used individually or in combination of two or more types.

[0014] The base rubber is preferably a diene-based rubber, and more preferably an acrylonitrile-butadiene-based rubber. The base rubber is even more preferably to contain at least one selected from the group consisting of carboxy-modified acrylonitrile-butadiene rubber (XNBR), hydrogenated acrylonitrile-butadiene rubber (HNBR), and hydrogenated carboxy-modified acrylonitrile-butadiene rubber (HXNBR). XNBR is a copolymer of a monomer having a carboxyl group, acrylonitrile, and butadiene. HNBR is a hydrogenated product of acrylonitrile-butadiene rubber. HXNBR is a hydrogenated product of a copolymer of a monomer having a carboxyl group, acrylonitrile, and butadiene.

[0015] The content of acrylonitrile-butadiene rubber in the base rubber is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. It is also preferable that the base rubber contains only acrylonitrile-butadiene rubber.

[0016] In the aforementioned NBR, XNBR, HNBR, and HXNBR, the acrylonitrile content is preferably 15% by mass or more, more preferably 18% by mass or more, even more preferably 21% by mass or more, preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. If the acrylonitrile content is 15% by mass or more, the abrasion resistance will be good, and if it is 50% by mass or less, the grip will feel good in cold regions or in winter.

[0017] In the HNBR and HXNBR mentioned above, the double bond content is preferably 0.09 mmol / g or more, more preferably 0.2 mmol / g or more, preferably 2.5 mmol / g or less, more preferably 2.0 mmol / g or less, and even more preferably 1.5 mmol / g or less. If the double bond content is 0.09 mmol / g or more, vulcanization during molding becomes easier, further improving the tensile strength of the grip, and if it is 2.5 mmol / g or less, the durability (weather resistance) and tensile strength of the grip are better. The double bond content can be adjusted by the butadiene content in the copolymer and the amount of hydrogenation added to the copolymer.

[0018] In the XNBR and HXNBR mentioned above, examples of monomers having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. In the XNBR and HXNBR mentioned above, the content of monomers containing a carboxyl group is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.5% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. If the content of monomers containing a carboxyl group is 1.0% by mass or more, the abrasion resistance will be better, and if it is 30% by mass or less, the grip will feel better in cold regions or in winter.

[0019] In the XNBR and HXNBR mentioned above, the carboxyl group content is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, even more preferably 3.5% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. If the carboxyl group content is 1.0% by mass or more, the abrasion resistance is better, and if it is 30% by mass or less, the grip feel in cold regions or winter is better.

[0020] Mooney viscosity (ML) of the aforementioned HXNBR 1+4 The Mooney viscosity (ML) is preferably 60 or higher, more preferably 64 or higher, even more preferably 68 or higher, preferably 95 or lower, more preferably 90 or lower, and even more preferably 85 or lower. 1+4 If the Mooney viscosity (ML) (at 100°C) is 60 or higher, the wear resistance of the grip is improved, and if it is 95 or lower, the processability of the rubber composition is good. Note that in this invention, Mooney viscosity (ML) 1+4 (100℃)) refers to the value measured in accordance with JIS K6300, using an L rotor, with a preheating time of 1 minute, a rotor rotation time of 4 minutes, and under conditions of 100℃.

[0021] (Hard, porous carbon particles) The aforementioned rigid porous carbon particles are porous carbon particles composed of at least a portion of rigid, glassy carbon. Because at least a portion of them are composed of rigid, glassy carbon, the carbon particles become rigid and can exhibit a microspike effect.

[0022] Preferably, the hard porous carbon particles consist of porous amorphous carbon and glassy carbon that covers at least a portion of the surface of the amorphous carbon. With such a configuration, it is easy to control the porosity and hardness of the hard porous carbon particles.

[0023] The average particle size of the hard porous carbon particles is preferably 30 μm or more, more preferably 60 μm or more, even more preferably 90 μm or more, preferably 500 μm or less, more preferably 450 μm or less, and even more preferably 400 μm or less. If the average particle size of the hard porous carbon particles is 30 μm or more, the microspike effect on the user's gloves, etc., on the rubber surface is further improved, and if it is 500 μm or less, the decrease in the mechanical strength of the crosslinked rubber obtained from the rubber composition can be suppressed. The average particle size was measured by mass average particle size in accordance with JIS K1474 (2014). Sieves with mesh openings of 0.500 mm, 0.425 mm, 0.250 mm, 0.150 mm, 0.106 mm, 0.090 mm, 0.053 mm, and 0.032 mm were used.

[0024] The porosity of the hard porous carbon particles is preferably 30 volume% or more, more preferably 32 volume% or more, even more preferably 34 volume% or more, preferably 60 volume% or less, more preferably 58 volume% or less, and even more preferably 56 volume% or less. If the porosity of the hard porous carbon particles is 30 volume% or more, improved adhesion with the rubber can be expected due to sufficient penetration of the rubber matrix, and if it is 60 volume% or less, pulverization during kneading when preparing the rubber composition is suppressed. The porosity is measured by the mercury intrusion method (mercury porosimeter).

[0025] The Vickers hardness of the hard porous carbon particles is preferably 1.0 GPa or higher, more preferably 1.5 GPa or higher, even more preferably 2.0 GPa or higher, preferably 6.0 GPa or lower, more preferably 5.5 GPa or lower, and even more preferably 5.0 GPa or lower. If the Vickers hardness of the hard porous carbon particles is 1.0 GPa or higher, pulverization during kneading when preparing the rubber composition is suppressed, and if it is 6.0 GPa or lower, no pain is felt when gripping the resulting grip. The Vickers hardness was measured using a micro-Vickers hardness tester under the conditions of a test force of 0.98 N and a test force holding time of 20 seconds.

[0026] The hard, porous carbon particles can be obtained, for example, by mixing a porous amorphous carbon raw material with a glassy carbon raw material and then carbonizing and calcining the resulting mixture under an inert gas atmosphere. The carbides may be crushed and classified after carbonization and calcination. Examples of raw materials for the porous amorphous carbon include wood and plant materials such as wheat bran, with rice bran and rice husks being preferred. Examples of raw materials for the glassy carbon include thermosetting resins, with phenolic resins being preferred. The carbonization firing temperature is preferably between 300°C and 1100°C.

[0027] The content of the hard porous carbon particles is preferably 1.5% by mass or more, more preferably 2.0% by mass or more, even more preferably 2.5% by mass or more, preferably 8.5% by mass or less, more preferably 8.2% by mass or less, and even more preferably 8.0% by mass or less, based on 100% by mass of the rubber composition. If the content of the hard porous carbon particles is 1.5% by mass or more, an improvement in the coefficient of friction of the rubber composition can be expected, and if it is 8.5% by mass or less, it will not function as a lubricant due to excessive addition.

[0028] The content of the hard porous carbon particles in the rubber composition is preferably 2.5 parts by mass or more, more preferably 2.7 parts by mass or more, even more preferably 2.9 parts by mass or more, preferably 16.0 parts by mass or less, more preferably 15.8 parts by mass or less, and even more preferably 15.6 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the hard porous carbon particles is 2.5 parts by mass or more, an improvement in the coefficient of friction of the rubber composition can be expected, and if it is 16.0 parts by mass or less, it will not function as a lubricant due to excessive addition.

[0029] (Vulcanizing agent) As the vulcanizing agent, sulfur-based vulcanizing agents and organic peroxides can be used. The vulcanizing agent may be used alone or in combination of two or more types.

[0030] Examples of the sulfur-based vulcanizing agent include elemental sulfur and sulfur donor compounds. Examples of elemental sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur. Examples of sulfur donor compounds include 4,4'-dithiobismorpholine. Examples of the aforementioned organic peroxides include dicumyl peroxide, α,α'-bis(t-butylperoxy-m-diisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane.

[0031] As the vulcanizing agent, a sulfur-based vulcanizing agent is preferred, and elemental sulfur is more preferred. Using a sulfur-based vulcanizing agent tends to improve the mechanical strength of the resulting crosslinked rubber. Furthermore, using a sulfur-based vulcanizing agent does not increase the bonding energy between rubber chains, resulting in a larger hysteresis loss during deformation and an improved coefficient of friction.

[0032] The content of the vulcanizing agent is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, even more preferably 0.6 parts by mass or more, preferably 4.0 parts by mass or less, more preferably 3.5 parts by mass or less, and even more preferably 3.0 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the vulcanizing agent is 0.2 parts by mass or more, vulcanization will proceed more easily, and if it is 4.0 parts by mass or less, the occurrence of scorching can be reduced.

[0033] (thermoplastic resin) The rubber composition may contain a thermoplastic resin (excluding a tackifier). The inclusion of the thermoplastic resin makes it possible to control the viscoelastic properties of the cured rubber composition, thereby improving the feel. The thermoplastic resin may be used alone or in combination of two or more types.

[0034] If the rubber composition contains the thermoplastic resin, the content of the thermoplastic resin is preferably 5 parts by mass or more, more preferably 7 parts by mass or more, even more preferably 9 parts by mass or more, preferably 40 parts by mass or less, more preferably 38 parts by mass or less, and even more preferably 36 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the thermoplastic resin is 5 parts by mass or more, the coefficient of friction of the resulting grip is further improved, and if it is 40 parts by mass or less, the decrease in strength of the cured product of the rubber composition is suppressed.

[0035] When the rubber composition contains the thermoplastic resin, the mass ratio of the rigid porous carbon particles to the thermoplastic resin (rigid porous carbon particles / thermoplastic resin) in the rubber composition is preferably 0.04 or higher, more preferably 0.10 or higher, even more preferably 0.15 or higher, preferably 3.5 or lower, more preferably 3.0 or lower, even more preferably 2.5 or lower, and particularly preferably 1.0 or lower. If the mass ratio (rigid porous carbon particles / thermoplastic resin) is 0.04 or higher, the friction coefficient and strength of the rubber composition can be balanced, and if it is 3.5 or lower, the dispersibility of the rigid porous carbon particles is improved.

[0036] Examples of the thermoplastic resin include ethylene-vinyl acetate copolymers and styrene-based elastomers.

[0037] The vinyl acetate content of the ethylene-vinyl acetate copolymer is preferably 10% by mass or more, more preferably 12% by mass or more, even more preferably 15% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. If the vinyl acetate content is 10% by mass or more, the grip feel is improved, and if it is 80% by mass or less, the wear resistance of the grip is further improved.

[0038] Mooney viscosity (ML) of the ethylene-vinyl acetate copolymer 1+4 (100℃) is preferably 20 or higher, more preferably 22 or higher, even more preferably 24 or higher, preferably 40 or lower, more preferably 38 or lower, and even more preferably 36 or lower.

[0039] Examples of the styrene-based elastomers include styrene-butadiene-styrene block copolymer (SBS), styrene-isobutylene-styrene block copolymer (SIBS), and styrene-ethylene-butylene-styrene block copolymer (SEBS).

[0040] (Vulcanization accelerator) The rubber composition may contain a vulcanization accelerator. The vulcanization accelerator may be used alone or in combination of two or more types.

[0041] The total content of the vulcanization accelerator in the rubber composition is preferably 4.4 parts by mass or more, more preferably 5.4 parts by mass or more, even more preferably 6.4 parts by mass or more, preferably 12.5 parts by mass or less, more preferably 10.5 parts by mass or less, and even more preferably 8.5 parts by mass or less, per 100 parts by mass of the base rubber. If the total content of the vulcanization accelerator is within the above range, the occurrence of bloom and the like can be further suppressed.

[0042] Examples of the aforementioned vulcanization accelerators include thiram-based vulcanization accelerators, sulfenamide-based vulcanization accelerators, thiourea-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators.

[0043] Thiuram-based vulcanization accelerator Examples of the thiram-based vulcanization accelerators include tetramethylthiram disulfide (TMTD), tetrabenzylthiram disulfide (TBzTD), tetramethylthiram monosulfide (TMTM), dipentamethylenethiram tetrasulfide, and tetrakis(2-ethylhexyl)thiram disulfide. While the thiram-based vulcanization accelerators may be used individually, it is preferable to use two or more in combination from the viewpoint of preventing blooming.

[0044] The content of the thiram-based vulcanization accelerator is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, preferably 9 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the thiram-based vulcanization accelerator is within the above range, even faster vulcanization can be achieved while maintaining scorch resistance, even in base rubber with a small amount of double bonds.

[0045] Sulfenamide-based vulcanization accelerator Examples of the sulfenamide-based vulcanization accelerators include N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS) and N-(tert-butyl)-2-benzothiazo-lsulfenamide (BBS). The sulfenamide-based vulcanization accelerators may be used alone or in combination of two or more types.

[0046] The content of the sulfenamide-based vulcanization accelerator is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.7 parts by mass or more, preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.5 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the sulfenamide-based vulcanization accelerator is within the above range, the occurrence of bloom can be further reduced.

[0047] Thiourea-based vulcanization accelerators Examples of the thiourea-based vulcanization accelerators include trimethylthiourea and N,N'-diethylthiourea. These thiourea-based vulcanization accelerators may be used alone or in combination of two or more types.

[0048] The content of the thiourea-based vulcanization accelerator is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, preferably 1.0 part by mass or less, more preferably 0.8 parts by mass or less, and even more preferably 0.6 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the thiourea-based vulcanization accelerator is within the above range, the thiram-based vulcanization accelerator can be activated and the vulcanization time can be further shortened.

[0049] Examples of the thiazole-based vulcanization accelerators include mercaptobenzothiazole (MBT) and benzothiazole disulfide. Examples of the guanidine-based vulcanization accelerator include diphenylguanidine (DPG). Examples of the dithiocarbamate-based vulcanization accelerators include zinc dimethyldithiocarbamate (ZnPDC) and zinc dibutyldithiocarbamate.

[0050] The rubber composition preferably contains a thiram-based vulcanization accelerator and a sulfenamide-based vulcanization accelerator as vulcanization accelerators. By including a thiram-based vulcanization accelerator and a sulfenamide-based vulcanization accelerator, a crosslinked rubber with excellent mechanical strength can be obtained even when vulcanization is performed at high temperatures.

[0051] The total content of the thiram-based vulcanization accelerator and the sulfenamide-based vulcanization accelerator in the rubber composition is preferably 4.5 parts by mass or more, more preferably 5.5 parts by mass or more, even more preferably 6.5 parts by mass or more, preferably 11.5 parts by mass or less, more preferably 10.0 parts by mass or less, and even more preferably 8.5 parts by mass or less, per 100 parts by mass of the base rubber. If the total content is 4.5 parts by mass or more, the vulcanization rate can be increased even with base rubber that has a small amount of double bonds, and if it is 11.5 parts by mass or less, the scorch resistance is improved in rubber with a small amount of double bonds.

[0052] The mass ratio (thiuram-based vulcanization accelerator / sulfenamide-based vulcanization accelerator) of the thiuram-based vulcanization accelerator in the rubber composition is preferably 1.5 or higher, more preferably 3.0 or higher, even more preferably 4.5 or higher, preferably 30 or lower, more preferably 20 or lower, and even more preferably 10 or lower. If the mass ratio (thiuram-based vulcanization accelerator / sulfenamide-based vulcanization accelerator) is 1.5 or higher, the vulcanization rate can be increased even with a base rubber having a small amount of double bonds, and if it is 30 or lower, the decrease in strength of the crosslinked rubber obtained during high-temperature and high-speed vulcanization can be further suppressed.

[0053] The rubber composition preferably contains a thiram-based vulcanization accelerator, a sulfenamide-based vulcanization accelerator, and a thiourea-based vulcanization accelerator as vulcanization accelerators. By including the thiourea-based vulcanization accelerator, the thiram-based vulcanization accelerator is activated, and the vulcanization time can be further shortened.

[0054] The total content of the thiram-based vulcanization accelerator, sulfenamide-based vulcanization accelerator, and thiourea-based vulcanization accelerator in the rubber composition is preferably 4.4 parts by mass or more, more preferably 5.4 parts by mass or more, even more preferably 6.4 parts by mass or more, preferably 12.5 parts by mass or less, more preferably 10.5 parts by mass or less, and even more preferably 9.5 parts by mass or less, per 100 parts by mass of the base rubber. If the total content is 4.4 parts by mass or more, the vulcanization rate can be increased even with base rubber that has a small amount of double bonds, and if it is 12.5 parts by mass or less, the scorch resistance is improved in rubber with a small amount of double bonds.

[0055] The mass ratio (thiuram-based vulcanization accelerator / thiourea-based vulcanization accelerator) of the thiuram-based vulcanization accelerator in the rubber composition is preferably 4 or more, more preferably 6 or more, even more preferably 8 or more, preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less. If the mass ratio (thiuram-based vulcanization accelerator / thiourea-based vulcanization accelerator) is 4 or more, the strength of the resulting crosslinked rubber is further improved, and if it is 20 or less, the activation of the thiuram-based accelerator by the thiourea-based accelerator is further improved.

[0056] (Vulcanizing activator) The rubber composition may further contain a vulcanizing activator. Examples of the vulcanizing activators include metal oxides, metal peroxides, and fatty acids. Examples of the metal oxides include zinc oxide, magnesium oxide, and lead oxide. Examples of the metal peroxides include zinc peroxide, chromium peroxide, magnesium peroxide, and calcium peroxide. Examples of the fatty acids include stearic acid, oleic acid, and palmitic acid. These vulcanizing activators may be used individually or in combination of two or more.

[0057] The total amount of the vulcanizing activator used is preferably 0.5 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.7 parts by mass or more, preferably 10.0 parts by mass or less, more preferably 9.5 parts by mass or less, and even more preferably 9.0 parts by mass or less, per 100 parts by mass of the base rubber.

[0058] (Reinforcement material) The rubber composition may contain a reinforcing material. However, the hard porous carbon particles are not included in the reinforcing material. Examples of the reinforcing material include carbon black, silica, and calcium carbonate. Furthermore, by incorporating a reinforcing material, the density of the crosslinked rubber can be adjusted, and the mass of the grip formed from the rubber composition can be adjusted. The specific surface area of ​​the reinforcing material is 1 m 2 / g~300m 2 / g is preferable.

[0059] If the rubber composition contains a reinforcing material, the amount of the reinforcing material is preferably 9 parts by mass or more, more preferably 14 parts by mass or more, even more preferably 19 parts by mass or more, preferably 36 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 24 parts by mass or less, per 100 parts by mass of the base rubber. If the amount of the reinforcing material is within the above range, it becomes easier to control the mass of the resulting grip to within the desired range.

[0060] If the rubber composition contains a reinforcing material, the total content of the reinforcing material and the hard porous carbon particles is preferably 12 parts by mass or more, more preferably 16 parts by mass or more, even more preferably 22 parts by mass or more, preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the base rubber. If the total content of the reinforcing material and the hard porous carbon particles is 12 parts by mass or more, a further improvement in the coefficient of friction of the rubber composition can be expected, and if it is 50 parts by mass or less, a significant decrease in the strength of the rubber composition can be suppressed.

[0061] (Tackifire) The rubber composition may further contain a tackifier. If the amount of the reinforcing material in the rubber composition is increased in order to adjust the density of the crosslinked rubber, the ratio of the crosslinked rubber (tanδ / E * ) tends to be large, but by incorporating tackifier, the ratio (tanδ / E * ) can be reduced.

[0062] Examples of the aforementioned tackifiers include rosin esters, coumarone resins, phenolic resins, terpene resins, terpene-phenolic resins, and styrene-based resins.

[0063] The rosin ester is an ester compound obtained by reacting the rosin with alcohols. Rosin is a natural resin containing abietic acid, neoabietic acid, palastic acid, pimaric acid, isopimaric acid, and dehydroabietic acid. The alcohols include monohydric alcohols such as n-octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, lauryl alcohol, and stearyl alcohol; dihydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, and neopentyl glycol; trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric alcohols such as pentaerythritol and diglycerin; and hexahydric alcohols such as dipentaerythritol and sorbitol. Among these, polyhydric alcohols of dihydric or higher hydrity are preferred, and glycerin is more preferred.

[0064] The rosin esters mentioned above include hydrogenated rosin esters and disproportionated rosin esters. The hydrogenated rosin esters and disproportionated rosin esters are so-called stabilized rosin esters.

[0065] The hydrogenated rosin ester is an ester compound in which at least a portion of the rosin-derived portion of a rosiene ester is hydrogenated. The hydrogenated rosin ester can be obtained by hydrogenating rosin and then reacting the hydrogenated rosin with an alcohol, or by reacting rosin with an alcohol and then hydrogenating the resulting rosin ester.

[0066] The disproportionated rosin ester is an ester compound in which at least a portion of the rosin-derived portion of the rosin ester is disproportionated. Disproportionated rosin esters can be obtained by disproportionating rosin and then reacting the disproportionated rosin with alcohols, or by reacting rosin with alcohols and then disproportionating the resulting rosin ester.

[0067] The coumarone resin is a resin containing coumarones as monomer components. Coumarone-indene resin is preferred as the coumarone resin. The coumarone-indene resin is a copolymer containing coumarones and indenes as monomer components, with a total content of coumarones and indenes of 50% by mass or more in the total monomer components. Examples of coumarones include coumarone and methylcoumarone. The content of coumarones in the total monomer components is preferably 1% to 20% by mass. Examples of indenes include indene and methylindene. The content of indenes in the total monomer components is preferably 40% to 95% by mass. The coumarone-indene resin may also contain other monomer components besides coumarones and indenes. Examples of other monomer components include styrene, vinyltoluene, and dicyclopentadiene.

[0068] Examples of the phenolic resin include condensates of phenols and formaldehyde. Examples of phenols include phenol and m-cresol. The phenolic resin also includes resol, which is obtained by an addition reaction of phenols and formaldehyde with an alkaline catalyst; and novolac, which is obtained by a condensation reaction with an acid catalyst. Furthermore, the phenolic resin also includes rosinphenol resin, which is obtained by adding phenols to rosin with an acid catalyst and then thermal polymerization.

[0069] If the rubber composition contains a tackifier, the tackifier content is preferably 5 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 7 parts by mass or more, preferably 20 parts by mass or less, more preferably 19 parts by mass or less, and even more preferably 18 parts by mass or less, per 100 parts by mass of the base rubber. If the resin content is 5 parts by mass or more, the resulting grip feel will be better, and if it is 20 parts by mass or less, the decrease in the mechanical strength of the cured product of the rubber composition will be suppressed.

[0070] (Processing aid) The rubber composition may also preferably contain processing aids. Examples of processing aids include internal lubricants and external lubricants. Examples of the internal lubricant include mineral oil and plasticizer. Examples of the mineral oil include paraffin oil, naphthenic oil, and aromatic oil. Examples of the plasticizer include dioctyl phthalate, dibutyl phthalate, dioctyl separator, and dioctyl adipate. Examples of the external lubricant include phosphate ester compounds and long-chain alkylamine compounds. The rubber composition preferably contains a phosphate ester compound as an external lubricant. By including a phosphate ester compound as an external lubricant, adhesion inside the equipment during kneading can be prevented even with a small amount of addition, and a homogeneous rubber composition can be obtained.

[0071] If the rubber composition contains an external lubricant, the content of the external lubricant is preferably 0.1 parts by mass or more, more preferably 0.15 parts by mass or more, even more preferably 0.25 parts by mass or more, preferably 1.0 part by mass or less, more preferably 0.75 parts by mass or less, and even more preferably 0.5 parts by mass or less, per 100 parts by mass of the base rubber. If the content of the external lubricant is within the above range, the lubricant effect is high and the occurrence of bloom can be suppressed.

[0072] The rubber composition may further contain, if necessary, an anti-aging agent, an anti-scorching agent, a coloring agent, and the like.

[0073] Examples of the aforementioned anti-aging agents include imidazoles, amines, phenols, and thioureas. Examples of the imidazoles include nickel dibutyldithiocarbamate (NDIBC), 2-mercaptobenzimidazole, and zinc salt of 2-mercaptobenzimidazole. Examples of amines include phenyl-α-naphthylamine. Examples of phenols include 2,2'-methylenebis(4-methyl-6-t-butylphenol) (MBMBP) and 2,6-di-tert-butyl-4-methylphenol. Examples of thioureas include tributylthiourea and 1,3-bis(dimethylaminopropyl)-2-thiourea. These anti-aging agents may be used individually or in combination of two or more.

[0074] If the rubber composition contains an anti-aging agent, the amount of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.4 parts by mass or more, preferably 5.0 parts by mass or less, more preferably 4.8 parts by mass or less, and even more preferably 4.6 parts by mass or less, per 100 parts by mass of the base rubber.

[0075] Examples of the scorching inhibitor include organic acids and nitroso compounds. Examples of the organic acids include phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, benzoic acid, salicylic acid, and malic acid. Examples of the nitroso compounds include N-nitroso-diphenylamine, N-(cyclohexylthio)phthalimide, sulfonamide derivatives, diphenylurea, bis(tridecyl)pentaerythulol diphosphite, and 2-mercaptobenzimidazole.

[0076] Examples of the coloring agent include inorganic pigments and organic pigments. Examples of the inorganic pigment include titanium dioxide, with rutile-type titanium dioxide being particularly preferred due to its high opacity. Examples of the organic pigment include azo pigments and phthalocyanine pigments.

[0077] The rubber composition may contain microballoons. By incorporating microballoons into the rubber composition, a porous grip structure can be obtained. Either organic or inorganic microballoons can be used as the microballoons. Examples of organic microballoons include hollow particles made of thermoplastic resin and resin capsules in which low-boiling point hydrocarbons are encapsulated in a thermoplastic resin shell.

[0078] The rubber composition can be prepared by conventionally known methods. For example, it can be prepared by kneading the raw materials using a kneader such as a Banbury mixer, kneader, or open roll. If the rubber composition contains microballoons, it is preferable to knead the components other than the microballoons beforehand, and then knead this mixture with the microballoons. When kneading the mixture with the microballoons, it is preferable to set the material temperature below the temperature at which the microballoons begin to expand.

[0079] (Vulcanization properties) The rubber composition preferably has a 90% vulcanization time (t90) of 5 min or less in the vulcanization curve measured at a vulcanization temperature of 185°C, more preferably 4.5 min or less, and even more preferably 4 min or less. A 90% vulcanization time of 5 min or less results in higher productivity. The lower limit of the 90% vulcanization time is not particularly limited, but is usually 3 min.

[0080] The aforementioned 90% vulcanization time is determined from the vulcanization curve measured at a vulcanization temperature of 185°C. Specifically, when the minimum torque in the vulcanization curve is defined as ML, the maximum torque as MH, and the difference between them as ME, the time required for the torque to become ML + 90%ME was defined as the 90% vulcanization time.

[0081] (Cross-linked rubber) Preferably, the cured product (crosslinked rubber) of the rubber composition has the physical properties described later. The vulcanization conditions for the rubber composition were a vulcanization temperature of 185°C and a vulcanization time of 2 minutes added to the 90% vulcanization time (t90) on the vulcanization curve.

[0082] Regarding the cured product of the rubber composition, measured under the measurement conditions of a vibration frequency of 10 Hz, a strain amplitude of 0.05%, and a tensile mode using a dynamic viscoelasticity apparatus, the loss factor (tanδ) and complex elastic modulus (E * )(MPa) ratio (tanδ / E * ) is preferably 0.030 or more, more preferably 0.031 or more, still more preferably 0.032 or more, preferably 0.040 or less, more preferably 0.039 or less, still more preferably 0.038 or less.

[0083] Regarding the cured product of the rubber composition, measured under the measurement conditions of a vibration frequency of 10 Hz, a strain amplitude of 0.05%, and a tensile mode using a dynamic viscoelasticity apparatus, the loss tangent (tanδ) at 25°C is preferably 0.10 or more, more preferably 0.12 or more, still more preferably 0.14 or more. If the loss tangent (tanδ) is 0.10 or more, the anti-slip performance of the obtained grip becomes better. The upper limit of the loss tangent (tanδ) is not particularly limited, but is preferably 0.26 or less, more preferably 0.24 or less, still more preferably 0.23 or less. If the loss tangent (tanδ) is 0.26 or less, it is possible to suppress excessive deflection of the cured product of the rubber composition.

[0084] Regarding the cured product of the rubber composition, measured under the measurement conditions of a vibration frequency of 10 Hz, a strain amplitude of 0.05%, and a tensile mode using a dynamic viscoelasticity apparatus, the complex elastic modulus (E * ) at 25°C is preferably 8.00 MPa or less, more preferably 7.90 MPa or less, still more preferably 7.80 MPa or less. If the complex elastic modulus (E * ) is 8.00 MPa or less, it is possible to suppress excessive hardness of the curing agent of the rubber composition. The lower limit of the complex elastic modulus (E * ) is not particularly limited, but is preferably 3.00 MPa or more, more preferably 3.20 MPa or more, still more preferably 3.40 MPa or more. If the complex elastic modulus (E * ) is 3.00 MPa or more, the hardness of the cured product of the rubber composition becomes more suitable for the hardness of the grip.

[0085] The cured product of the aforementioned rubber composition has a density of 1.05 g / cm³. 3 Preferably, it is 1.06 g / cm³ or more, and more preferably 1.06 g / cm³. 3 More preferably 1.07 g / cm³ 3 The above is 1.10 g / cm³. 3 The following is preferred, and more preferably, 1.09 g / cm³. 3 More preferably, 1.08 g / cm³ 3 The following applies: If the density is within the above range, the weight of the single-layer grip formed from the rubber composition will be about the same as that of a conventional grip, and it can be replaced without any problems.

[0086] The hardness of the cured product of the rubber composition is preferably 50 or higher on the Shore A hardness scale, more preferably 52 or higher, even more preferably 54 or higher, preferably 65 or lower, more preferably 63 or lower, and even more preferably 61 or lower. If the hardness of the cured product is 50 or higher on the Shore A hardness scale, the mechanical strength of the grip is further improved, and if it is 65 or lower, the grip does not become too hard, resulting in a better feel when gripped.

[0087] The cured product of the rubber composition preferably has a tensile strength (Tb) at break of 9 MPa or more, more preferably 10 MPa or more, and even more preferably 11 MPa or more. A tensile strength at break of 9 MPa or more results in better abrasion resistance of the grip. There is no particular upper limit to the tensile strength at break of the cured product of the rubber composition, but it is preferably 40 MPa or less, more preferably 39 MPa or less, and even more preferably 38 MPa or less.

[0088] The cured product of the rubber composition preferably has an elongation at break (Eb) of 300% or more, more preferably 320% or more, and even more preferably 340% or more. An elongation at break of 300% or more can further suppress problems such as grip breakage when inserting a shaft into the grip. There is no particular upper limit to the elongation at break of the cured product of the rubber composition, but it is usually 800%.

[0089] The rubber composition for grips of the present invention is used for molding grips. Because the rubber composition for grips has an excellent coefficient of friction after curing, it is suitable for use in golf club grips.

[0090] [Golf club grips] The golf club grip of the present invention is characterized by having a cylindrical portion, and at least a part of the cylindrical portion being formed from the rubber grip composition. That is, at least a part of the cylindrical portion is made of cross-linked rubber obtained by vulcanizing the rubber grip composition.

[0091] The golf club grip has a cylindrical portion into which the shaft is inserted. The cylindrical portion can be constructed as a single layer, a two-layer structure, a three-layer structure, or the like. When the cylindrical portion has a single layer structure, the entire cylindrical portion is made of the rubber composition. When the cylindrical portion has a multilayer structure, at least one layer is made of the rubber composition. When the cylindrical portion has a multilayer structure, it is preferable that at least the outermost layer is made of the rubber composition.

[0092] The cylindrical portion of the golf club grip is preferably a single-layer structure. Since the rubber composition for the grip can be vulcanized at high temperatures, even thick members can be molded in a short time. Therefore, if a single-layer cylindrical portion is manufactured using the rubber composition for the grip, the structure is simple and the vulcanization time is shortened, further improving the productivity of the grip. Furthermore, the density of the crosslinked rubber formed from the rubber composition is 1.05 g / cm³. 3 ~1.10g / cm 3 Therefore, the weight of the single-layer grip formed from the aforementioned rubber composition will be about the same as that of a conventional grip, and it can be replaced without any problems.

[0093] The cylindrical portion may be a solid structure or a porous structure. If the cylindrical portion is a solid structure, the mechanical strength of the grip will be increased, and if the cylindrical portion is a porous structure, the weight of the grip can be reduced.

[0094] Golf club grips are obtained by molding the rubber composition in a mold. Molding methods include press molding and injection molding. Furthermore, a golf club grip having an inner layer and an outer layer can be obtained, for example, by press molding a laminate of an unvulcanized rubber sheet formed from the outer layer rubber composition and an unvulcanized rubber sheet formed from the inner layer rubber composition in a mold.

[0095] [Golf clubs] The present invention also includes a golf club using the golf club grip described above. The golf club comprises a shaft, a head attached to one end of the shaft, and a grip attached to the other end of the shaft, wherein the grip is the golf club grip. The shaft can be made of stainless steel or carbon fiber reinforced resin. The head can be a wood type, a utility type, or an iron type. The material constituting the head is not particularly limited and can be titanium, titanium alloy, carbon fiber reinforced plastic, stainless steel, maraging steel, soft iron, etc.

[0096] The following describes the golf club grip and golf club with reference to the drawings. Figure 1 is a perspective view showing an example of a golf club grip. The grip 1 has a cylindrical portion 2 into which the shaft is inserted, and a cap portion 3 integrally formed to cover the opening at the rear end of the cylindrical portion. The cylindrical portion 2 has a single-layer structure. The thickness of the cylindrical portion 2 is formed to gradually increase from the front end to the rear end. In the grip 1 shown in Figure 1, the cap portion 3 is formed from the same rubber composition as the cylindrical portion 2.

[0097] Figure 2 is a perspective view showing an example of a golf club equipped with the golf club grip of the present invention. The golf club 4 comprises a shaft 5, a head 6 attached to one end of the shaft 5, and a grip 1 attached to the other end of the shaft 4. The rear end of the shaft 5 is fitted into the cylindrical portion 2 of the grip 1. [Examples]

[0098] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and any modifications and embodiments that do not depart from the spirit of the present invention are all included within the scope of the present invention.

[0099] [Evaluation Method] (1) Acrylonitrile content The acrylonitrile content was measured in acrylonitrile-butadiene rubber before hydrogenation according to ISO 24698-1 (2008).

[0100] (2) Double bond content (mmol / g) The double bond content was calculated from the butadiene content (mass%) and the amount of remaining double bonds (%) in the copolymer. The amount of remaining double bonds is the mass ratio of the double bonds in the copolymer before hydrogenation to the double bonds in the copolymer after hydrogenation (amount of double bonds after hydrogenation / amount of double bonds before hydrogenation), and can be measured by infrared spectroscopy. If the acrylonitrile-butadiene rubber is an acrylonitrile-butadiene binary copolymer, the butadiene content in the copolymer can be determined by subtracting the acrylonitrile content (mass%) from 100. Double bond amount = {butadiene content / 54} × remaining double bond amount × 10

[0101] (3) Content of monomers containing carboxyl groups 1 g of hydrogenated carboxylated acrylonitrile-butadiene rubber was weighed out and dissolved in 50 mL of chloroform, to which thymol blue indicator was added dropwise. While stirring this solution, a 0.05 mol / L methanol solution of sodium hydroxide was added dropwise, and the volume (V mL) until the first color change occurred was recorded. As a blank, 50 mL of chloroform without hydrogenated carboxylated acrylonitrile-butadiene rubber was also prepared, and a 0.05 mol / L methanol solution of sodium hydroxide was added dropwise using thymol blue as an indicator, and the volume (B mL) until the first color change occurred was recorded. The carboxyl group content was calculated using the following formula. Carboxylic group monomer content = {0.05 × (VB) × PM} / (10 × X) (In the formula, V: volume of sodium hydroxide solution dropped as the test solution (mL), B: volume of sodium hydroxide solution dropped as the blank (mL), PM: molecular weight of the carboxyl group-containing monomer, X: valence of the carboxyl group-containing monomer)

[0102] (4) Vulcanization test The rubber compositions were subjected to vulcanization tests using a vulcanization tester (Curlastometer® Type 7, manufactured by JSR Trading Co., Ltd.) at the vulcanization temperatures listed in Table 2. Following "Method A of Die Vulcanization Test" in JIS K6300-2 (2001), "Method for Determining Vulcanization Characteristics Using a Vibration-Type Vulcanization Tester," a low-amplitude sinusoidal vibration, not damaging the rubber test piece, was applied from the lower die, and the torque transmitted from the test piece to the upper die was measured from unvulcanized to overvulcanized. The measurement conditions were a torsional vibration frequency of 100 times per minute, an amplitude angle of 1°, and a measurement time of 30 minutes. From the obtained vulcanization curves, the minimum (ML) and maximum (MH) torque values, as well as the 90% vulcanization time (t90), were determined.

[0103] (5) Hardness (Shore A hardness) A 2 mm thick sheet was prepared by vulcanizing the rubber composition under the conditions described in Table 2. This sheet was stored at 23°C for two weeks, and its hardness was measured using an automated hardness tester (H. Barleys, DigiTest II) with three sheets stacked together to avoid interference from the measurement substrate. The "Shore A" detector was used.

[0104] (6) Density (g / cm 3 ) Using the rubber composition, a 13 cm square, 2 mm thick sheet was prepared by vulcanization under the conditions described in Table 2. Test specimens were prepared by punching out 2 cm squares from this sheet. The density (23°C) of the obtained test specimens was measured using an automatic hydrometer (MSTEC Co., Ltd., SP-GR1, Archimedes' principle).

[0105] (7) Tensile strength at break (MPa), elongation at break (%) The tensile strength and elongation at break were measured in accordance with JIS K 6251 (2017). Specifically, a 1 mm thick sheet was prepared by vulcanizing the rubber composition under the conditions described in Table 2, and this sheet was punched out into a dumbbell shape (Dumbbell Type 3) to prepare test specimens. The physical properties were measured using a tensile testing device (Shimadzu Corporation, Autograph® AGS-D) (measurement temperature 23°C, tensile speed 500 mm / min). The tensile strength at break was calculated by dividing the tensile force recorded when the test specimen broke by the cross-sectional area of ​​the test specimen before testing.

[0106] (8) Viscoelasticity Loss tangent (tanδ), complex modulus of elasticity (E * The viscoelasticity was measured using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM). The test specimens were prepared by slicing the grip in the thickness direction to a thickness of 1.6 mm and punching them out to the specified size. The measurement conditions were: temperature; -100°C to 100°C, heating rate; 3°C / min, measurement interval; 3°C, frequency; 10 Hz, strain amplitude; 10%, jig; tensile, specimen shape; width 4 mm, thickness 2 mm, length 40 mm. The loss tangent (tanδ) and complex modulus (E) at 25°C were obtained from the viscoelastic spectrum obtained by dynamic viscoelastic measurement. * ) was sought.

[0107] (9) Coefficient of friction The static and dynamic friction coefficients were measured using a static and dynamic friction measuring instrument (Trinity Labs, Tribomaster). The test specimen was prepared by slicing the grip to a thickness of 1.6 mm in the thickness direction, removing the groove pattern, and punching it out to a width of 10 mm and a length of 20 mm, which was then fixed to the flat contact of the device. In addition, natural leather cut from the palm of a golf glove (Sumitomo Rubber Industries, XXIO® Golf Glove (GGG-X008)) was fixed to the movable table. The measurement conditions were a load of 25g, a travel speed of 1mm / sec, and a travel distance of 10mm. The kinetic friction coefficient was calculated by averaging the kinetic friction coefficient from 2000ms to 6000ms from the start of measurement. If no static friction coefficient appeared during the measurement, the friction coefficient immediately before the occurrence of the stick-slip phenomenon due to kinetic friction was adopted as the static friction coefficient. The friction coefficient is shown as an indexed value, with the friction coefficient of crosslinked rubber No. 4 set to 100.

[0108] [Preparation of rubber composition] The rubber composition was prepared by kneading each raw material according to the formulations shown in Table 1. All raw materials were kneaded in a closed-type kneader.

[0109] [Table 1]

[0110] The materials used in Table 1 are as follows: HXNBR: Hydrogenated carboxylated acrylonitrile-butadiene rubber (manufactured by ARANXEO, Thermal XT VPKA 8889 (residual double bond content 3.5%, acrylonitrile content 33.0% by mass, double bond content 0.40 mmol / g, carboxyl group monomer content 5.0% by mass)) Hard, porous carbon particles: Manufactured by Sanwa Oil & Fat Co., Ltd., RB Ceramics (carbon particles composed of porous amorphous carbon and glassy carbon coating at least a portion of the surface of this amorphous carbon) (average particle size 200 μm, average porosity 50 volume%, Vickers hardness 4.3 GPa) EVA: Ethylene-vinyl acetate copolymer (manufactured by ARANXEO, Levapren 500 (vinyl acetate content 50% by mass, Mooney viscosity (ML)) 1+4 (100℃) 27) Sulfur: Tsurumi Chemical Industry Co., Ltd., Kinka brand 5% oil-containing fine sulfur powder (200 mesh) Zinc peroxide: Struktol ZP 1014 (29% by mass zinc peroxide content), manufactured by Struktol. Thiuram-based accelerator 1: Sanshin Chemical Industry Co., Ltd., "Sunceller (registered trademark) TBzTD" (tetrabenzyl thiuram disulfide) Thiuram-based accelerator 2: "Noxellar (registered trademark) TOT-N" (tetrakis(2-ethylhexyl) thiuram disulfide), manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Thiourea-based accelerator: "Noxellar EUR" (N,N'-diethylthiourea), manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfenamide-based accelerator: "Sunceller NS-G" (N-(tert-butyl)-2-benzothiazole sulfenamide), manufactured by Sanshin Chemical Industry Co., Ltd. Solid tackifier: Eastman Chemical Company, "Staybelite Ester 10-E" (partially hydrogenated rosin ester) Liquid tackifier: Arizona Chemical, "SYLVATAC RE-5S" (rosin ester (melting point below 25°C)) Carbon Black: Manufactured by Tokai Carbon Co., Ltd., SEAST (registered trademark) 3 (specific surface area 79 m²) 2 / g) Silica: Manufactured by Tosoh Corporation, NipSeal (registered trademark) VN3 (specific surface area 180-230 m²) 2 / g) Calcium carbonate: Manufactured by Shiraishi Calcium Co., Ltd., Softon 3200 (specific surface area 3.2 m²) 2 / g) Rutile-type titanium dioxide: Manufactured by Ishihara Sangyo Co., Ltd., CR60 vanfre VAM: Polyoxyethylene-octadecyl ether-phosphate, manufactured by Vanderbilt Chemicals.

[0111] [Making the grip] The rubber composition was placed in a mold with a groove pattern on the cavity surface. The rubber was then vulcanized under the conditions described in Table 2 to induce a crosslinking reaction, yielding a golf club grip. The viscoelastic properties and friction coefficient of the grip were evaluated, and the results are shown in Table 2.

[0112] [Table 2]

[0113] Rubber compositions No. F to H contain a base rubber, hard porous carbon particles, and a vulcanizing agent. Grips made using these rubber compositions No. F to H exhibited a high coefficient of static friction. Rubber compositions No. A to E do not contain hard, porous carbon particles. Grips made using these rubber compositions No. A to E had a low coefficient of static friction.

[0114] The present invention (1) is a rubber composition for grips that contains a base rubber, hard porous carbon particles, and a vulcanizing agent, wherein at least a portion of the hard porous carbon particles is composed of glassy carbon, and the content of the hard porous carbon particles is 1.5% to 8.5% by mass in 100% by mass of the rubber composition.

[0115] The present invention (2) is a rubber composition for grip according to the present invention (1), wherein the base rubber contains at least one selected from the group consisting of carboxylated acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, and hydrogenated carboxylated acrylonitrile-butadiene rubber.

[0116] The present invention (3) is a grip rubber composition according to the present invention (1) or (2), wherein the ratio of the loss coefficient (tanδ) to the complex modulus of elasticity (E*) (MPa) (tanδ / E*) at 25°C, measured using a dynamic viscoelastic device under measurement conditions of an excitation frequency of 10 Hz, a strain amplitude of 0.05%, and a tensile mode, is 0.030 to 0.040.

[0117] The present invention (4) is a grip rubber composition according to any one of the present inventions (1) to (3), wherein the tensile strength at break of the cured grip rubber composition is 9 MPa or more.

[0118] The present invention (5) relates to a case in which the density of the cured product of the rubber composition for grip is 1.05 g / cm³. 3 ~1.10g / cm 3 This is a rubber composition for grips according to any one of the present invention (1) to (4).

[0119] The present invention (6) is a grip rubber composition according to any one of the present inventions (1) to (5), wherein the hardness of the cured product of the grip rubber composition is 50 to 65 on the Shore A hardness scale.

[0120] The present invention (7) is a golf club grip having a cylindrical portion, wherein at least a part of the cylindrical portion is formed from a rubber grip composition described in any one of the present inventions (1) to (6). [Explanation of Symbols]

[0121] 1: Grip, 2: Cylindrical part, 3: Cap part, 4: Golf club, 5: Shaft, 6: Head

Claims

1. It contains a base rubber, hard porous carbon particles, and a vulcanizing agent. The hard porous carbon particles are composed of at least a portion of glassy carbon. A rubber composition for grips, characterized in that the content of the hard porous carbon particles is 1.5% to 8.5% by mass in 100% by mass of the rubber composition.

2. The rubber composition for grip according to claim 1, wherein the base rubber contains at least one selected from the group consisting of carboxylated acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, and hydrogenated carboxylated acrylonitrile-butadiene rubber.

3. The grip rubber composition according to claim 1, wherein the ratio of the loss coefficient (tanδ) to the complex modulus of elasticity (E*) (MPa) (tanδ / E*) at 25°C, measured using a dynamic viscoelastic device under measurement conditions of an excitation frequency of 10 Hz, a strain amplitude of 0.05%, and a tensile mode, is 0.030 to 0.

040.

4. The grip rubber composition according to claim 1, wherein the tensile strength at break of the cured product of the grip rubber composition is 9 MPa or more.

5. The density of the cured product of the aforementioned rubber composition for grips is 1.05 g / cm³. 3 ~1.10 g / cm 3 The rubber composition for grip according to claim 1.

6. The grip rubber composition according to claim 1, wherein the hardness of the cured product of the grip rubber composition is 50 to 65 on the Shore A hardness scale.

7. A golf club grip having a cylindrical portion, wherein at least a portion of the cylindrical portion is formed from a rubber grip composition according to any one of claims 1 to 6.

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