Golf club shaft

Abstract

An object of the present invention is to provide a golf club shaft which is light in weight but can exhibit good durability and can suppress a decrease in flex. The golf club shaft according to the present invention has a mass within a range of 30 g or more and 60 g or less. The shaft also exhibits a flex within the range of 8 kg or more and 20 kg or less. The shaft has a durability of 1200 times or more when a golf ball is hit at a head speed of 38 m / s with a head attached to the tip of the shaft having a mass less than 45 g, and the shaft has a durability of 1800 times or more when the golf ball is hit at a head speed of 44 m / s with the head attached to the tip of the shaft having a mass 45 g or more.

Description

TECHNICAL FIELD

[0001] The present invention relates to a shaft of golf club.BACKGROUND ART

[0002] In recent years, the weight of a shaft of golf club has been reduced for the purpose of improving a hit ball flight distance, and various techniques for reducing the weight of a shaft have been proposed in the past (for example, see Japanese Patent Application Publication No. 2009-229444 and 2012-130533.PRIOR ART DOCUMENTPatent Document

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-229444

[0004] Patent Document 2: Japanese Patent Application Publication No. 2012-130533SUMMARY OF THE INVENTIONProblem to be Solved by the Invention

[0005] When the weight of the shaft is reduced, not only the durability of the shaft is reduced but also the flex is reduced (that is, the shaft is easily bent) in many cases. An object of the present invention is to provide a shaft of golf club which is light in weight but can exhibit good durability and can suppress a decrease in flex.Means for Solving the Problem

[0006] A shaft of golf club according to a first aspect of the present invention has a mass within a range of 30 g or more and 60 g or less. The shaft also exhibits a flex within the range of 8 kg or more and 20 kg or less. The shaft has the number of times of a durability of 1200 times or more when a golf ball is hit at a head speed of 38 m / s with a head attached to the tip of the shaft having a mass less than 45 g, and the shaft has the number of times of a durability of 1800 times or more when the golf ball is hit at a head speed of 44 m / s with a head attached to the tip of the shaft having a mass 45 g or more. The shaft length is preferably 1170±2 mm.

[0007] Therefore, although the shaft light in weight, the shaft can exhibit good durability and can suppress a decrease in flex.

[0008] A shaft of golf club according to a second aspect of the present invention is the shaft of golf club according to the first aspect, which is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. The first prepreg includes a first fiber in a range of 20 g / m2 or more and 100 g / m2 or less. The first prepreg is continuously wound two or more turns such that the orientation angle of the first fiber is in a range of 80° or more and 100° or less. The second prepreg includes a second fiber. The second fiber have a fiber elastic modulus in a range of 350 GPa or more and 800 GPa or less. The second prepreg is wound adjacent to the first prepreg on the outer side of the first prepreg such that the orientation angle of the second fiber is within the range of ±30° or more and ±40° or less. The outermost prepreg includes a third fiber. The third fiber have a fiber breaking elongation in a range of 1.5% or more and 3.0% or less. The outermost prepreg is wound on the outer side of the second prepreg such that the orientation angle of the third fibers is in the range of −5° or more and 5° or less. Another prepreg may be provided between the second prepreg and the outermost prepreg as appropriate depending on the purpose. Here, the orientation angle is determined with reference to the axis of the shaft. That is, the axis of the shaft is set to 0 °.

[0009] Therefore, the shaft can be manufactured by using a conventional prepreg lamination technique.

[0010] A shaft of golf club according to a third aspect of the present invention is the shaft of golf club according to the second aspect, further including a decorative layer. The decorative layer is made of paint, print, at least one of fabric and a unidirectional fiber sheet. In this case, the decorative layer is the outermost layer of the shaft of golf club in terms of arrangement, but is a completely different layer in terms of function. In addition, it is preferable that a prepreg using a fiber having a fiber breaking elongation in a range of 1.5% or more and 3.0% or less is used for the decorative layer.

[0011] Thus, the shaft can have a characteristic design.DETAILED DESCRIPTION OF THE INVENTION

[0012] The shaft of the golf club according to the embodiment of the present invention is a so-called lightweight shaft, and has a mass within a range of 30 g or more and 60 g or less when the length is 1170±2 mm. The mass is preferably in a range of 30 g or more and 55 g or less, more preferably in a range of 30 g or more and 50 g or less, still more preferably in a range of 30 g or more and 45 g or less, and particularly preferably in a ran89657 30 g or more and 40 g or less. However, there may be a case where a golf player prefers a shaft of the golf club having a large mass.

[0013] The shaft also exhibits a flex within the range of 8 kg or more and 20 kg or less. The preferred range of the flex varies depending on the mass band described above. When the mass of the shaft is in the range of 30 g or more and 38 g or less, the flex is preferably in the range of 8 kg or more and 10.4 kg or less, when the mass of the shaft is in the range of more than 38 g and 43 g or less, the flex is preferably in the range of 10.5 kg or more and 11.9 kg or less, when the mass of the shaft is in the range of more than 43 g and 49 g or less, the flex is preferably in the range of 12 kg or more and 15.4 kg or less, and when the mass of the shaft is in the range of more than 49 g and 60 g or less, the flex is preferably in the range of 15.5 kg or more and 20 kg or less.

[0014] The shaft also exhibits symmetrical torque characteristics in accordance with the Golf Association regulations.

[0015] The durability of the shaft when a golf ball is hit at a head speed of 38 m / s with a head mounted on the tip side of the shaft having a mass less than 45 g is 1200 times or more, and the durability of the shaft when the golf ball is hit at the head speed of 44 m / s with the head mounted on the tip side of the shaft having a mass 45 g or more is 1800 times or more. The number of times of durability is preferably 1800 times or more when the mass of the shaft is less than the 45 g. In the embodiment of the present invention, the “number of times of durability of the shaft” refers to the number of times that no damage such as microcracks is observed on the surface of the shaft when the surface of the shaft is observed with an optical microscope after a golf ball is hit with a golf club to which the shaft is attached. The number of times of durability is measured by, for example, a test shot by a robot having high repeatability such as Golf Shot Robot 3DX manufactured by Miyamae Co., Ltd. The head used in the measurements is a TaylorMade M1 460 or equivalent (such as a head with a titanium face and around mass of 200 g). It should be noted that the durability test is relatively little affected by the material of the face of the head, etc., because the golf ball is hit with the heel. The golf ball was a ball of Titleist Pro V1 manufactured by Acushnet Company or an equivalent (the ball is a commercially available ball having around mass of 45.93 g in accordance with the Rules of Golf, having a hardness equivalent to Titleist Pro V1).

[0016] The shaft of the golf club according to the embodiment of the present invention is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. In the production of the shaft according to the embodiment of the present invention, a prepreg having a resin content of 20 mass% or less is not used. Hereinafter, each of the above-described prepregs will be described in detail. In the description of each prepreg, the orientation angle of the fiber is defined, and the orientation angle is determined with reference to the axis of the shaft. That is, the axis of the shaft is set to 0 °.

[0017] The first prepreg contains a first fiber in a range of 20 g / m2 or more and 100 g / m2 or less. The first prepreg preferably contains the first fiber in a range of 20 g / m2 or more and 90 g / m2 or less, more preferably contains the first fiber in a range of 20 g / m2 or more and 80 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 70 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 60 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 50 g / m2 or less, and particularly preferably contains the first fiber in a range of 20 g / m2 or more and 40 g / m2 or less. The first fiber is preferably a carbon fiber. The first prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The first prepreg is continuously wound two or more turns such that the orientation angle of the first fiber is in a range of 80° or more and 100° or less. The orientation angle is preferably in the range of 85° or more and 95° or less. In addition, the first prepreg is preferably a uni-directional prepreg, that is, a prepreg in which the first fibers are aligned in one direction.

[0018] The second prepreg contains a second fiber. The second fiber is preferably a carbon fiber. The second prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The second fiber has a fiber elastic modulus in a range of 350 GPa or more and 800 GPa or less. The fiber elastic modulus depends on the intended properties of the shaft, and is preferably in the range of 350 GPa or more and 800 GPa or less, more preferably in the range of 350 GPa or more and 700 GPa or less, still more preferably in the range of 350 GPa or more and 600 GPa or less, and particularly preferably in the range of 350 GPa or more and 500 GPa or less. The second fiber preferably has a fiber breaking elongation in the range of 0.7 % or more and less than 1.5 %, more preferably in the range of 0.8 % or more and less than 1.5 %, still more preferably in the range of 1.0 % or more and less than 1.5 %, and particularly preferably in the range of 1.2 % or more and less than 1.5 %. The second prepreg is wound adjacent to the first prepreg on the outer side of the first prepreg such that the orientation angle of the second fiber is within the range of ±30 °or more and ±40° or less. The orientation angle is preferably in a range of ±30° or more and ±35° or less in a case of suppressing a decrease in flex, and is preferably in a range of ±35° or more and ±40° or less in a case of suppressing a decrease in torque. In addition, the second prepreg is preferably a uni-directional prepreg, that is, a prepreg in which the second fibers are aligned in one direction.

[0019] The outermost prepreg contains a third fiber. The third fiber is preferably a carbon fiber, and among them, a PAN-based carbon fiber is preferable. The outermost prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The third fiber has a fiber breaking elongation in a range of 1.5% or more and 3.0% or less. The fiber breaking elongation is preferably in a range of 1.8% or more and 3.0% or less, more preferably in a range of 2.0% or more and 3.0% or less, further preferably in a range of 2.1% or more and 3.0% or less, further preferably in a range of 2.2% or more and 3.0% or less, and particularly preferably in a range of 2.5% or more and 3.0% or less. The third fiber preferably has a fiber elastic modulus in the range of 230 GPa or more and less than 350 GPa, more preferably in the range of 290 GPa or more and 350 GPa or less, and further preferably in the range of 320 GPa or more and 350 GPa or less. The outermost prepreg is wound on the outer side of the second prepreg such that the orientation angle of the third fiber is in the range of −5° or more and 5° or less. The outermost prepreg may be a UD prepreg (Uni-Directional prepreg, prepreg in which carbon fibers are aligned in one direction) or a woven fabric prepreg. When the outermost prepreg is a woven fabric prepreg, the orientation angle of the fiber orthogonal to the third fiber is in the range of 85° or more and 95° or less.

[0020] In the shaft according to the embodiment of the present invention, the outermost prepreg may be subjected to decorative finishing by coating, wrapping film, or the like, or a decorative layer made of at least one of a fabric and a unidirectional fiber sheet may be formed on the outermost prepreg.

[0021] The above-described prepreg laminate structure allows the shaft to have an apparent rigidity in the longitudinal direction while maintaining good torque performance, and thus allows the shaft to be lightweight, have high initial rigidity, and exhibit good durability.WORKING EXAMPLE 11. Production of Carbon Shaft

[0022] A first UD prepreg (an uni-directional prepreg, prepreg in which carbon fibers were aligned in one direction) containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. The orientation angle referred to herein is an angle formed by the carbon fibers with respect to the axis of the mandrel, and finally becomes an angle with respect to the axis of the shaft. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 125 g / m2 was wound once on the second UD prepreg such that the orientation angle of the carbon fibers was 0°, and furthermore a fourth UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 100 g / m2 was wound once thereon such that the orientation angle of the carbon fibers was 0°. Subsequently, a fifth UD prepreg (corresponding to the “outermost prepreg” in claim 2) containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 125 g / m2 was wound around the upper side of the fourth UD prepreg one turn each such that the orientation angle of the carbon fibers was 0°. Thereafter, as a decorative layer, a carbon-fiber fabric made of carbon fibers exhibiting elasticity of 230 GPa was wound one turn on the upper side of the fifth prepreg so that the orientation angle of the carbon fibers in the carbon-fiber fabric was 0° / 90°, and then the laminated prepreg was vacuum-sealed with a bagging film. Then, the laminated prepreg in this state was cured in an autoclave to obtain a target carbon shaft. The resin constituting each prepreg was a same type as 130 °C-curing type epoxy resin. The length of the carbon shaft was 1170 mm.2. Measurement of Physical Properties of Carbon Shaft(1) Mass Measurement

[0024] The mass of the carbon shaft was measured with a weighing machine and found to be 48.5 g.

[0025] (2) Flex Measurement

[0026] The flex of the carbon shaft was measured using an Auditor Golf Shaft Profiler based on the Golf Standard, and the flex of the carbon shaft was found to be 15.3 kg.

[0027] (3) Torque Measurement

[0028] The torque of the carbon shaft was measured using an Auditor Digital Shaft Torque Meter based on the Golf Standard, and the torque of the carbon shaft was 6.7 °.

[0029] (4) Durability Test

[0030] A “M 1 460” manufactured by TaylorMade Golf Co. was mounted on the tip side of the carbon shaft to assemble a golf club, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1800 times with the head with heel hitting at a head speed of 44 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.WORKING EXAMPLE 2

[0031] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the fifth UD prepreg in WORKING EXAMPLE 1 was replaced with a UD prepreg having carbon fibers exhibiting elasticity of 324 GPa and elongation at break of 2.0%, and no decorative layer was provided.

[0032] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.5 g, the flex was 16.9 kg, and the torque was 7.3 °. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 3

[0033] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg and the fourth UD prepreg in WORKING EXAMPLE 1 were replaced with prepregs having carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0034] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.6 g, the flex was 10.9 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 4

[0035] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the decorative layer in WORKING EXAMPLE 1 was replaced with a prepreg having a carbon fibrous fabric composed of carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0036] When various physical properties of the carbon shaft were measured according to various measurement methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.8 g, the flex was 15.1 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 5

[0037] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg in WORKING EXAMPLE 1 was replaced with a prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 75g / m2 , the fourth UD prepreg and the fifth UD prepreg were replaced with prepregs containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 75g / m2 , and the decorative layer was replaced with a carbon fibrous fabric composed of carbon fibers exhibiting elasticity of 294 GPa When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 38.4 g, the flex was 10.3 kg, and the torque was 8.0°. A golf club was assembled by mounting a “M 1 460” manufactured by TaylorMade Golf Co. on the tip side of the carbon shaft, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1200 times with the head with heel hitting at a head speed of 38 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.WORKING EXAMPLE 6

[0038] A first UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 150 g / m2 was wound once on the second UD prepreg such that the orientation angle of the carbon fibers was 0°, and furthermore a fourth UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 150 g / m2 was wound once thereon such that the orientation angle of the carbon fibers was 0°. Subsequently, a fifth UD prepreg (corresponding to the “outermost prepreg” in claim 2) containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 125 g / m2 was wound around the upper side of the fourth UD prepreg one turn each such that the orientation angle of the carbon fibers was 0°. Thereafter, as a decorative layer, a carbon-fiber fabric made of carbon fibers exhibiting elasticity of 294 GPa was wound one turn on the upper side of the fifth prepreg so that the orientation angle of the carbon fibers in the carbon-fiber fabric was 0° / 90°, and then the laminated prepreg was vacuum-sealed with a bagging film. Then, the laminated prepreg in this state was cured in an autoclave to obtain a target carbon shaft. The resin constituting each prepreg was a same type as 130 °C-curing type epoxy resin. The length of the carbon shaft was 1170 mm.

[0039] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 60.0 g, the flex was 19.0 kg, and the torque was 5.3 °. A golf club was assembled by mounting a “M 1 460” manufactured by TaylorMade Golf Co. on the tip side of the carbon shaft, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1800 times with the head with heel hitting at a head speed of 46 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.COMPARATIVE EXAMPLE 1

[0040] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the winding of the first prepreg around the mandrel in WORKING EXAMPLE 3 was changed to one turn, and the first prepreg was wound one turn again after the second prepreg was wound.

[0041] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.7 g, the flex was 11.1 kg, and the torque was 6.9°. When the golf ball was hit under the same conditions as those shown in WORKING EXAMPLE 1, the shaft was broken before the number of hits reached 1800.COMPARATIVE EXAMPLE 2

[0042] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg, the fourth UD prepreg, and the fifth UD prepreg in WORKING EXAMPLE 1 were replaced with UD prepregs having carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2%.

[0043] When various physical properties of the carbon shaft were measured according to various measurement methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.8 g, the flex was 15.7 kg, and the torque was 6.7°. When the golf ball was hit under the same conditions as those shown in WORKING EXAMPLE 1, the shaft was broken before the number of hits reached 1800.INDUSTRIAL APPLICABILITY

[0044] The shaft of the golf club according to the present invention is lightweight, but can exhibit good durability, and can suppress a decrease in flex, and can achieve a dream of improving a ball hitting distance of a user.

Examples

working example 1

1. Production of Carbon Shaft

[0022]A first UD prepreg (an uni-directional prepreg, prepreg in which carbon fibers were aligned in one direction) containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. The orientation angle referred to herein is an angle formed by the carbon fibers with respect to the axis of the mandrel, and finally becomes an angle with respect to the axis of the shaft. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 125 g / m2 was wound once on the second UD prepreg such that the ori...

working example 2

[0031]A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the fifth UD prepreg in WORKING EXAMPLE 1 was replaced with a UD prepreg having carbon fibers exhibiting elasticity of 324 GPa and elongation at break of 2.0%, and no decorative layer was provided.

[0032]When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.5 g, the flex was 16.9 kg, and the torque was 7.3 °. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.

working example 3

[0033]A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg and the fourth UD prepreg in WORKING EXAMPLE 1 were replaced with prepregs having carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0034]When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.6 g, the flex was 10.9 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.

TECHNICAL FIELD

[0001] The present invention relates to a shaft of golf club.BACKGROUND ART

[0002] In recent years, the weight of a shaft of golf club has been reduced for the purpose of improving a hit ball flight distance, and various techniques for reducing the weight of a shaft have been proposed in the past (for example, see Japanese Patent Application Publication No. 2009-229444 and 2012-130533.PRIOR ART DOCUMENTPatent Document

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-229444

[0004] Patent Document 2: Japanese Patent Application Publication No. 2012-130533SUMMARY OF THE INVENTIONProblem to be Solved by the Invention

[0005] When the weight of the shaft is reduced, not only the durability of the shaft is reduced but also the flex is reduced (that is, the shaft is easily bent) in many cases. An object of the present invention is to provide a shaft of golf club which is light in weight but can exhibit good durability and can suppress a decrease in flex.Means for Solving the Problem

[0006] A shaft of golf club according to a first aspect of the present invention has a mass within a range of 30 g or more and 60 g or less. The shaft also exhibits a flex within the range of 8 kg or more and 20 kg or less. The shaft has the number of times of a durability of 1200 times or more when a golf ball is hit at a head speed of 38 m / s with a head attached to the tip of the shaft having a mass less than 45 g, and the shaft has the number of times of a durability of 1800 times or more when the golf ball is hit at a head speed of 44 m / s with a head attached to the tip of the shaft having a mass 45 g or more. The shaft length is preferably 1170±2 mm.

[0007] Therefore, although the shaft light in weight, the shaft can exhibit good durability and can suppress a decrease in flex.

[0008] A shaft of golf club according to a second aspect of the present invention is the shaft of golf club according to the first aspect, which is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. The first prepreg includes a first fiber in a range of 20 g / m2 or more and 100 g / m2 or less. The first prepreg is continuously wound two or more turns such that the orientation angle of the first fiber is in a range of 80° or more and 100° or less. The second prepreg includes a second fiber. The second fiber have a fiber elastic modulus in a range of 350 GPa or more and 800 GPa or less. The second prepreg is wound adjacent to the first prepreg on the outer side of the first prepreg such that the orientation angle of the second fiber is within the range of ±30° or more and ±40° or less. The outermost prepreg includes a third fiber. The third fiber have a fiber breaking elongation in a range of 1.5% or more and 3.0% or less. The outermost prepreg is wound on the outer side of the second prepreg such that the orientation angle of the third fibers is in the range of −5° or more and 5° or less. Another prepreg may be provided between the second prepreg and the outermost prepreg as appropriate depending on the purpose. Here, the orientation angle is determined with reference to the axis of the shaft. That is, the axis of the shaft is set to 0 °.

[0009] Therefore, the shaft can be manufactured by using a conventional prepreg lamination technique.

[0010] A shaft of golf club according to a third aspect of the present invention is the shaft of golf club according to the second aspect, further including a decorative layer. The decorative layer is made of paint, print, at least one of fabric and a unidirectional fiber sheet. In this case, the decorative layer is the outermost layer of the shaft of golf club in terms of arrangement, but is a completely different layer in terms of function. In addition, it is preferable that a prepreg using a fiber having a fiber breaking elongation in a range of 1.5% or more and 3.0% or less is used for the decorative layer.

[0011] Thus, the shaft can have a characteristic design.DETAILED DESCRIPTION OF THE INVENTION

[0012] The shaft of the golf club according to the embodiment of the present invention is a so-called lightweight shaft, and has a mass within a range of 30 g or more and 60 g or less when the length is 1170±2 mm. The mass is preferably in a range of 30 g or more and 55 g or less, more preferably in a range of 30 g or more and 50 g or less, still more preferably in a range of 30 g or more and 45 g or less, and particularly preferably in a ran89657 30 g or more and 40 g or less. However, there may be a case where a golf player prefers a shaft of the golf club having a large mass.

[0013] The shaft also exhibits a flex within the range of 8 kg or more and 20 kg or less. The preferred range of the flex varies depending on the mass band described above. When the mass of the shaft is in the range of 30 g or more and 38 g or less, the flex is preferably in the range of 8 kg or more and 10.4 kg or less, when the mass of the shaft is in the range of more than 38 g and 43 g or less, the flex is preferably in the range of 10.5 kg or more and 11.9 kg or less, when the mass of the shaft is in the range of more than 43 g and 49 g or less, the flex is preferably in the range of 12 kg or more and 15.4 kg or less, and when the mass of the shaft is in the range of more than 49 g and 60 g or less, the flex is preferably in the range of 15.5 kg or more and 20 kg or less.

[0014] The shaft also exhibits symmetrical torque characteristics in accordance with the Golf Association regulations.

[0015] The durability of the shaft when a golf ball is hit at a head speed of 38 m / s with a head mounted on the tip side of the shaft having a mass less than 45 g is 1200 times or more, and the durability of the shaft when the golf ball is hit at the head speed of 44 m / s with the head mounted on the tip side of the shaft having a mass 45 g or more is 1800 times or more. The number of times of durability is preferably 1800 times or more when the mass of the shaft is less than the 45 g. In the embodiment of the present invention, the “number of times of durability of the shaft” refers to the number of times that no damage such as microcracks is observed on the surface of the shaft when the surface of the shaft is observed with an optical microscope after a golf ball is hit with a golf club to which the shaft is attached. The number of times of durability is measured by, for example, a test shot by a robot having high repeatability such as Golf Shot Robot 3DX manufactured by Miyamae Co., Ltd. The head used in the measurements is a TaylorMade M1 460 or equivalent (such as a head with a titanium face and around mass of 200 g). It should be noted that the durability test is relatively little affected by the material of the face of the head, etc., because the golf ball is hit with the heel. The golf ball was a ball of Titleist Pro V1 manufactured by Acushnet Company or an equivalent (the ball is a commercially available ball having around mass of 45.93 g in accordance with the Rules of Golf, having a hardness equivalent to Titleist Pro V1).

[0016] The shaft of the golf club according to the embodiment of the present invention is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. In the production of the shaft according to the embodiment of the present invention, a prepreg having a resin content of 20 mass% or less is not used. Hereinafter, each of the above-described prepregs will be described in detail. In the description of each prepreg, the orientation angle of the fiber is defined, and the orientation angle is determined with reference to the axis of the shaft. That is, the axis of the shaft is set to 0 °.

[0017] The first prepreg contains a first fiber in a range of 20 g / m2 or more and 100 g / m2 or less. The first prepreg preferably contains the first fiber in a range of 20 g / m2 or more and 90 g / m2 or less, more preferably contains the first fiber in a range of 20 g / m2 or more and 80 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 70 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 60 g / m2 or less, further preferably contains the first fiber in a range of 20 g / m2 or more and 50 g / m2 or less, and particularly preferably contains the first fiber in a range of 20 g / m2 or more and 40 g / m2 or less. The first fiber is preferably a carbon fiber. The first prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The first prepreg is continuously wound two or more turns such that the orientation angle of the first fiber is in a range of 80° or more and 100° or less. The orientation angle is preferably in the range of 85° or more and 95° or less. In addition, the first prepreg is preferably a uni-directional prepreg, that is, a prepreg in which the first fibers are aligned in one direction.

[0018] The second prepreg contains a second fiber. The second fiber is preferably a carbon fiber. The second prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The second fiber has a fiber elastic modulus in a range of 350 GPa or more and 800 GPa or less. The fiber elastic modulus depends on the intended properties of the shaft, and is preferably in the range of 350 GPa or more and 800 GPa or less, more preferably in the range of 350 GPa or more and 700 GPa or less, still more preferably in the range of 350 GPa or more and 600 GPa or less, and particularly preferably in the range of 350 GPa or more and 500 GPa or less. The second fiber preferably has a fiber breaking elongation in the range of 0.7 % or more and less than 1.5 %, more preferably in the range of 0.8 % or more and less than 1.5 %, still more preferably in the range of 1.0 % or more and less than 1.5 %, and particularly preferably in the range of 1.2 % or more and less than 1.5 %. The second prepreg is wound adjacent to the first prepreg on the outer side of the first prepreg such that the orientation angle of the second fiber is within the range of ±30 °or more and ±40° or less. The orientation angle is preferably in a range of ±30° or more and ±35° or less in a case of suppressing a decrease in flex, and is preferably in a range of ±35° or more and ±40° or less in a case of suppressing a decrease in torque. In addition, the second prepreg is preferably a uni-directional prepreg, that is, a prepreg in which the second fibers are aligned in one direction.

[0019] The outermost prepreg contains a third fiber. The third fiber is preferably a carbon fiber, and among them, a PAN-based carbon fiber is preferable. The outermost prepreg also contains a resin such as an epoxy resin, and the resin may be a conventional resin. The third fiber has a fiber breaking elongation in a range of 1.5% or more and 3.0% or less. The fiber breaking elongation is preferably in a range of 1.8% or more and 3.0% or less, more preferably in a range of 2.0% or more and 3.0% or less, further preferably in a range of 2.1% or more and 3.0% or less, further preferably in a range of 2.2% or more and 3.0% or less, and particularly preferably in a range of 2.5% or more and 3.0% or less. The third fiber preferably has a fiber elastic modulus in the range of 230 GPa or more and less than 350 GPa, more preferably in the range of 290 GPa or more and 350 GPa or less, and further preferably in the range of 320 GPa or more and 350 GPa or less. The outermost prepreg is wound on the outer side of the second prepreg such that the orientation angle of the third fiber is in the range of −5° or more and 5° or less. The outermost prepreg may be a UD prepreg (Uni-Directional prepreg, prepreg in which carbon fibers are aligned in one direction) or a woven fabric prepreg. When the outermost prepreg is a woven fabric prepreg, the orientation angle of the fiber orthogonal to the third fiber is in the range of 85° or more and 95° or less.

[0020] In the shaft according to the embodiment of the present invention, the outermost prepreg may be subjected to decorative finishing by coating, wrapping film, or the like, or a decorative layer made of at least one of a fabric and a unidirectional fiber sheet may be formed on the outermost prepreg.

[0021] The above-described prepreg laminate structure allows the shaft to have an apparent rigidity in the longitudinal direction while maintaining good torque performance, and thus allows the shaft to be lightweight, have high initial rigidity, and exhibit good durability.WORKING EXAMPLE 11. Production of Carbon Shaft

[0022] A first UD prepreg (an uni-directional prepreg, prepreg in which carbon fibers were aligned in one direction) containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. The orientation angle referred to herein is an angle formed by the carbon fibers with respect to the axis of the mandrel, and finally becomes an angle with respect to the axis of the shaft. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 125 g / m2 was wound once on the second UD prepreg such that the orientation angle of the carbon fibers was 0°, and furthermore a fourth UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 100 g / m2 was wound once thereon such that the orientation angle of the carbon fibers was 0°. Subsequently, a fifth UD prepreg (corresponding to the “outermost prepreg” in claim 2) containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 125 g / m2 was wound around the upper side of the fourth UD prepreg one turn each such that the orientation angle of the carbon fibers was 0°. Thereafter, as a decorative layer, a carbon-fiber fabric made of carbon fibers exhibiting elasticity of 230 GPa was wound one turn on the upper side of the fifth prepreg so that the orientation angle of the carbon fibers in the carbon-fiber fabric was 0° / 90°, and then the laminated prepreg was vacuum-sealed with a bagging film. Then, the laminated prepreg in this state was cured in an autoclave to obtain a target carbon shaft. The resin constituting each prepreg was a same type as 130 °C-curing type epoxy resin. The length of the carbon shaft was 1170 mm.2. Measurement of Physical Properties of Carbon Shaft(1) Mass Measurement

[0024] The mass of the carbon shaft was measured with a weighing machine and found to be 48.5 g.

[0025] (2) Flex Measurement

[0026] The flex of the carbon shaft was measured using an Auditor Golf Shaft Profiler based on the Golf Standard, and the flex of the carbon shaft was found to be 15.3 kg.

[0027] (3) Torque Measurement

[0028] The torque of the carbon shaft was measured using an Auditor Digital Shaft Torque Meter based on the Golf Standard, and the torque of the carbon shaft was 6.7 °.

[0029] (4) Durability Test

[0030] A “M 1 460” manufactured by TaylorMade Golf Co. was mounted on the tip side of the carbon shaft to assemble a golf club, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1800 times with the head with heel hitting at a head speed of 44 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.WORKING EXAMPLE 2

[0031] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the fifth UD prepreg in WORKING EXAMPLE 1 was replaced with a UD prepreg having carbon fibers exhibiting elasticity of 324 GPa and elongation at break of 2.0%, and no decorative layer was provided.

[0032] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.5 g, the flex was 16.9 kg, and the torque was 7.3 °. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 3

[0033] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg and the fourth UD prepreg in WORKING EXAMPLE 1 were replaced with prepregs having carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0034] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.6 g, the flex was 10.9 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 4

[0035] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the decorative layer in WORKING EXAMPLE 1 was replaced with a prepreg having a carbon fibrous fabric composed of carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0036] When various physical properties of the carbon shaft were measured according to various measurement methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.8 g, the flex was 15.1 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.WORKING EXAMPLE 5

[0037] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg in WORKING EXAMPLE 1 was replaced with a prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 75g / m2 , the fourth UD prepreg and the fifth UD prepreg were replaced with prepregs containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 75g / m2 , and the decorative layer was replaced with a carbon fibrous fabric composed of carbon fibers exhibiting elasticity of 294 GPa When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 38.4 g, the flex was 10.3 kg, and the torque was 8.0°. A golf club was assembled by mounting a “M 1 460” manufactured by TaylorMade Golf Co. on the tip side of the carbon shaft, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1200 times with the head with heel hitting at a head speed of 38 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.WORKING EXAMPLE 6

[0038] A first UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 150 g / m2 was wound once on the second UD prepreg such that the orientation angle of the carbon fibers was 0°, and furthermore a fourth UD prepreg containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 150 g / m2 was wound once thereon such that the orientation angle of the carbon fibers was 0°. Subsequently, a fifth UD prepreg (corresponding to the “outermost prepreg” in claim 2) containing carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0% at 125 g / m2 was wound around the upper side of the fourth UD prepreg one turn each such that the orientation angle of the carbon fibers was 0°. Thereafter, as a decorative layer, a carbon-fiber fabric made of carbon fibers exhibiting elasticity of 294 GPa was wound one turn on the upper side of the fifth prepreg so that the orientation angle of the carbon fibers in the carbon-fiber fabric was 0° / 90°, and then the laminated prepreg was vacuum-sealed with a bagging film. Then, the laminated prepreg in this state was cured in an autoclave to obtain a target carbon shaft. The resin constituting each prepreg was a same type as 130 °C-curing type epoxy resin. The length of the carbon shaft was 1170 mm.

[0039] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 60.0 g, the flex was 19.0 kg, and the torque was 5.3 °. A golf club was assembled by mounting a “M 1 460” manufactured by TaylorMade Golf Co. on the tip side of the carbon shaft, the golf club was mounted on a golf shot Robo 3DX manufactured by Miyamae Co., Ltd., a Titleist Pro V1 golf ball manufactured by Acushnet Company was hit 1800 times with the head with heel hitting at a head speed of 46 m / s by the golf shot Robo 3DX, and then entire surfaces of the carbon shaft were observed with an optical microscope, and as a result, no defects including microcracks were confirmed.COMPARATIVE EXAMPLE 1

[0040] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the winding of the first prepreg around the mandrel in WORKING EXAMPLE 3 was changed to one turn, and the first prepreg was wound one turn again after the second prepreg was wound.

[0041] When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.7 g, the flex was 11.1 kg, and the torque was 6.9°. When the golf ball was hit under the same conditions as those shown in WORKING EXAMPLE 1, the shaft was broken before the number of hits reached 1800.COMPARATIVE EXAMPLE 2

[0042] A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg, the fourth UD prepreg, and the fifth UD prepreg in WORKING EXAMPLE 1 were replaced with UD prepregs having carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2%.

[0043] When various physical properties of the carbon shaft were measured according to various measurement methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.8 g, the flex was 15.7 kg, and the torque was 6.7°. When the golf ball was hit under the same conditions as those shown in WORKING EXAMPLE 1, the shaft was broken before the number of hits reached 1800.INDUSTRIAL APPLICABILITY

[0044] The shaft of the golf club according to the present invention is lightweight, but can exhibit good durability, and can suppress a decrease in flex, and can achieve a dream of improving a ball hitting distance of a user.

Examples

working example 1

1. Production of Carbon Shaft

[0022]A first UD prepreg (an uni-directional prepreg, prepreg in which carbon fibers were aligned in one direction) containing carbon fibers exhibiting elasticity of 294 GPa at 25 g / m2 was continuously wound around a metal mandrel twice such that the orientation angle of the carbon fibers was 90°. The orientation angle referred to herein is an angle formed by the carbon fibers with respect to the axis of the mandrel, and finally becomes an angle with respect to the axis of the shaft. Next, two sheets of second UD prepreg containing carbon fibers exhibiting elasticity of 475 GPa and elongation at break of 0.8% at 75 g / m2 were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and wound around the upper side of the first UD prepreg twice. Next, a third UD prepreg containing carbon fibers exhibiting elasticity of 377 GPa and elongation at break of 1.2% at 125 g / m2 was wound once on the second UD prepreg such that the ori...

working example 2

[0031]A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the fifth UD prepreg in WORKING EXAMPLE 1 was replaced with a UD prepreg having carbon fibers exhibiting elasticity of 324 GPa and elongation at break of 2.0%, and no decorative layer was provided.

[0032]When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 48.5 g, the flex was 16.9 kg, and the torque was 7.3 °. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.

working example 3

[0033]A target carbon shaft was produced according to the method described in “1. Production of Carbon Shaft” in WORKING EXAMPLE 1 except that the third UD prepreg and the fourth UD prepreg in WORKING EXAMPLE 1 were replaced with prepregs having carbon fibers exhibiting elasticity of 294 GPa and elongation at break of 2.0%.

[0034]When various physical properties of the carbon shaft were measured according to various measuring methods described in “2. Measurement of Physical Properties of Carbon Shaft” in WORKING EXAMPLE 1, the mass was 47.6 g, the flex was 10.9 kg, and the torque was 6.8°. Further, when the entire surface of the shaft was observed with a microscope after the golf ball was hit 1800 times under the same conditions as those shown in WORKING EXAMPLE 1, no defects including microcracks were confirmed on the entire surface of the shaft.

Claims

1. (canceled)2. (canceled)3. (canceled)4. A shaft of golf club,wherein the golf club shaft is formed by laminatinga first prepreg including a first fiber in a range from 20 g / m2 to 100g / m2 , the first prepreg being continuously wound two or more times such that an orientation angle of the first fiber is in a range from 80° to 100°;a second prepreg including a second fiber having a fiber elastic modulus in a range from 350 GPa to 800 GPa, the second prepreg being wound outside the first prepreg so as to be adjacent to the first prepreg such that an orientation angle of the second fiber is in a range from ±30° to ±40°; andan outermost prepreg including a third fiber having a fiber breaking elongation in a range from 1.5% to 3.0%, the outermost prepreg being wound outside the second prepreg such that an orientation angle of the third fiber is in a range from −5° to 5°.

5. The shaft of golf club according to claim 4, further comprising a decorative layer formed of at least one of a woven fabric and a unidirectional fiber sheet.

6. The shaft of golf club according to claim 4,wherein the shaft has a mass within a range from 30 g to 60 g, and indicates a flex within a range from 8 kg to 20 kg;when a ball is hit at a head speed of 38 m / s with a head mounted on the tip end side of shaft of golf club having a mass less than 45 g, the number of times of durability is 1200 or more, and when the ball is hit at a head speed of 44 m / s with the head mounted on the tip end side of shaft of golf club having a mass 45 g or more, the number of times of durability is 1800 or more.

7. The shaft of golf club according to claim 5,wherein the shaft has a mass within a range from 30 g to 60 g, and indicates a flex within a range from 8 kg to 20 kg,when a ball is hit at a head speed of 38 m / s with a head mounted on the tip end side of shaft of golf club having a mass less than 45 g, the number of times of durability is 1200 or more, and when the ball is hit at a head speed of 44 m / s with the head mounted on the tip end side of shaft of golf club having a mass 45 g or more, the number of times of durability is 1800 or more.