JP2016010554A - Shaft for golf club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft for a golf club, enabling obtaining an appropriate amount of spin in accordance with a head speed, and a stable launch angle, and having high bending hardness.SOLUTION: A shaft for a golf club is configured such that: at least one layer of straight layers positioned across the entire shaft comprises a first straight layer formed from prepreg 24a arranged in a part from a small-diameter end to 850 mm of the shaft for a golf club, and a second straight layer formed from prepreg 24b arranged in a part from a large-diameter side end of the first straight layer to a large-diameter end of the golf shaft; an elasticity modulus of carbon fiber in the first straight layer is 50-350 GPa; an elasticity modulus of carbon fiber in the second straight layer is 50-350 GPa; and a difference between the elasticity modulus of carbon fiber in the first straight layer and the elasticity modulus of carbon fiber in the second straight layer is 40-100 GPa.

Description

  The present invention relates to a golf club shaft.

  It is known that the flight distance of a golf ball is determined by the initial velocity, launch angle, and spin rate of the ball. In order to improve the golf score, the stability of the flight distance is very important. Therefore, in order to obtain a stable flight distance, it is necessary to reduce the variation of these three elements. .

  The initial velocity, launch angle, and spin amount of the ball depend on the characteristics of the golf head, but the stability (motion) of the shaft at the moment of hitting the ball affects the stability of these three elements. In particular, the deformation of the small diameter portion of the golf club shaft (hereinafter sometimes referred to simply as the shaft) greatly affects these elements, and if the bending rigidity of the shaft of this portion is increased, the amount of deformation of the shaft can be suppressed. These elements are known to be stable.

  However, simply increasing the bending rigidity of the small-diameter shaft of the golf club shaft has disadvantages such as a hard feeling and poor head return. In addition, in a fiber reinforced resin shaft reinforced with carbon fiber, if the amount of carbon fiber having a high elastic modulus is excessively increased in order to increase the bending rigidity of the shaft, carbon fiber having a high elastic modulus is generally tensile. Since the strength is low, the strength of the shaft is lowered, and the shaft is easily broken. Furthermore, if the bending rigidity of this part is too high, head toe down will be suppressed too much, and it will be easier for the ball to hit the lower part than the center of the head, resulting in a trajectory with a low launch angle and a large amount of backspin. , Easy to lose flight distance.

  On the other hand, Patent Document 1 describes that variation in launch angle can be suppressed by increasing the bending rigidity of a shaft of 5 mm to 50 mm from the hosel portion of the club head.

  However, if the bending rigidity between 5 mm and 50 mm from the hosel part of the club head is increased as in Patent Document 1, the bending rigidity of the shaft of the hosel part of the club head becomes extremely low. There is a drawback that the shaft is easily broken.

  Contrary to the above, if the bending rigidity of the small-diameter portion of the golf club shaft is lowered, there is an advantage that the return of the head is improved, the ball launch angle is increased, and the flight distance is easily improved. However, if the bending rigidity of the shaft in the vicinity of the head is too low, the hit points are likely to vary, and there is a demerit that the flying distance is not stable. In addition, in a fiber-reinforced resin shaft reinforced with carbon fibers in order to reduce the bending rigidity of the shaft, if the amount of carbon fiber used is reduced, the strength of the shaft is lowered and the shaft is easily broken.

  On the other hand, in Patent Documents 2 and 3, the use of carbon fibers of 5 to 150 GPa for the reinforcing layer makes it possible to reduce the bending rigidity of the shaft without reducing the strength.

  However, in Patent Documents 2 and 3, although it is possible to reduce the bending rigidity of the shaft without reducing the strength, it is not possible to obtain a stable launch angle and spin amount.

  Further, the inventor of the present invention has a specific rigidity in a small-diameter portion as a shaft having high bending rigidity of the thin-diameter portion of the shaft, suppressing deformation of the thin-diameter portion of the shaft, and having sufficient bending strength. A shaft provided so that the first fiber reinforced resin layer and the second fiber reinforced resin layer do not overlap is proposed (see Patent Document 4).

Japanese Patent No. 3518783 Japanese Patent No. 3296970 Japanese Patent No. 3317619 JP 2009-189554 A

  However, in the shaft described in Patent Document 4, although the vertical and horizontal launch angles are stable, there is a large amount of backspin, and there is a tendency that a sufficient flight distance cannot be obtained.

  The present invention has been made in view of the above circumstances, can stabilize the backspin amount at an appropriate value, and can realize an ideal trajectory and flight distance without changing the weight balance of the shaft. And it aims at provision of the shaft for golf clubs which also has high bending strength.

  In order to achieve the above object, the present invention employs the following configuration.

(1) A golf club shaft comprising a plurality of carbon fiber reinforced resin layers,
A bias layer in which a layer in which carbon fibers are oriented at +30 to + 70 ° with respect to the shaft axis direction and a layer oriented at −30 to −70 ° are stacked;
Carbon fibers are oriented in the axial direction of the shaft, and two or more straight layers positioned over the entire length of the shaft;
The carbon fiber has a small-diameter side straight layer oriented in the shaft axial direction,
At least one of the straight layers positioned over the entire shaft is disposed on a portion extending from the narrow end to 850 mm of the shaft for the golf club, and the large diameter side of the first straight layer And a second straight layer disposed in a portion extending from the end of the golf shaft to the large diameter end of the golf shaft, and the elastic modulus of the carbon fiber in the first straight layer is 50 to 350 GPa, and the second straight The elastic modulus of the carbon fiber in the layer is 50 to 350 GPa, and the difference between the elastic modulus of the carbon fiber in the first straight layer and the elastic modulus of the carbon fiber in the second straight layer is 40 to 100 GPa,
A golf club characterized in that at least one of the straight layers located over the entire shaft is a fiber reinforced resin layer having reinforcing fibers that are not cut from the small diameter end to the large diameter end of the golf shaft. Shaft.

(2) The golf club shaft according to (1), wherein the elastic modulus of the carbon fiber in the first straight layer <the elastic modulus of the carbon fiber in the second straight layer.

(3) The golf club shaft according to (1), wherein the elastic modulus of the carbon fiber in the first straight layer is greater than the elastic modulus of the carbon fiber in the second straight layer.

  (4) The narrow-diameter side straight layer includes at least a narrow-diameter end of the first thin-diameter-side straight layer disposed in a portion extending from at least the small-diameter end to 100 mm of the golf club shaft and the golf club shaft. To a portion extending from 150 mm to 200 mm, and a second thin-diameter-side straight layer disposed so as not to overlap the first thin-diameter-side straight layer, in the first thin-diameter-side straight layer The carbon fiber has an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more, and the carbon fiber in the second small diameter straight layer has an elastic modulus of 100 GPa or less and a tensile elongation of 1.2. % Of the golf club shaft according to any one of the above (1) to (3).

  (5) A straight layer composed of a fiber reinforced resin layer in which the straight layer composed of the first straight layer and the second straight layer has reinforcing fibers that are not cut from the small diameter end to the large diameter end of the golf shaft. The golf club shaft according to any one of the above (1) to (4), which is disposed on the inner side.

  According to the golf club shaft of the present invention, it is possible to obtain an appropriate backspin amount in accordance with the head speed, to obtain a stable launch angle, and to have a high bending strength. Furthermore, an ideal trajectory and flight distance can be realized without changing the weight balance of the shaft.

  Specifically, for a user with a slow head speed (38 m / s or less), an appropriate spin rate (about 230 to 250 rpm) can be realized with a high trajectory, and a high flight distance can be secured by carry. Users with an average head speed (38 to 42 m / s) can achieve an appropriate spin rate (about 220 to 240 rpm) with a medium trajectory, and can secure a high carry distance for carry and run. For users with a fast head speed (42 m / s or more), a strong trajectory that does not blow up can be realized, and a high flight distance can be secured by suppressing the spin rate.

It is explanatory drawing which shows the cutting shape of the prepreg which comprises this, and the winding order about one embodiment of the shaft for golf clubs of this invention. It is a schematic explanatory drawing of the mandrel used in the Example. It is explanatory drawing which shows the cutting shape of the prepreg used for manufacture of the shaft for golf clubs in an Example, and the winding order to a mandrel. It is the schematic of the three-point bending test apparatus of the shaft for golf clubs. It is explanatory drawing which shows the cutting shape of the prepreg used for manufacture of the shaft for golf clubs by a comparative example, and the winding order to a mandrel.

  The present invention will be described in detail below.

  For example, the golf club shaft of the present invention is formed by winding prepregs 21 to 27 having cut shapes as shown in patterns 1 to 7 in FIG. 1 around the mandrel 10 in the order of patterns 1 to 7 and then heat-curing. A plurality of fiber-reinforced resin layers, a joining straight layer (first straight layer and second straight layer), and a narrow-side straight layer (first narrow-side straight layer and Second fine diameter side straight layer).

  The joining straight layer is formed by laminating layers in which carbon fibers having different elastic moduli are oriented at 0 ° with respect to the shaft axis direction. In this example, the joining straight layer is formed from the prepreg 24, specifically, the first layer straight layer is formed from the prepreg 24a, and the second straight layer is formed from the prepreg 24b. On the other hand, the narrow-side straight layer is a layer in which carbon fibers are oriented in the shaft axial direction, and is formed from the prepreg 22. Specifically, the first small-diameter side straight layer is formed from the prepreg 22a, and the second small-diameter side straight layer is formed from the prepreg 22b.

  Hereinafter, each layer will be described.

[Joint straight layer]
The joining straight layer is a layer composed of the prepreg 24 of the pattern 4 in FIG. 1, and is composed of a first straight layer formed from the prepreg 24a and a second straight layer formed from the prepreg portion 24b. Become. In this example, each of the prepregs 24a and 24b is a layer oriented at 0 °, and carbon fibers having different elastic moduli are connected to each other.

  Of the prepregs 24, the prepreg 24a corresponding to the first straight layer is disposed on the small diameter end (left end in the figure) side of the shaft, and the prepreg 24b corresponding to the second straight layer is larger in diameter than the prepreg 24a. Placed on the side. The prepreg 24a and the prepreg 24b are arranged such that their cut surfaces are abutted at the abutting portion 30a so as not to overlap each other, and the pattern 4 is formed.

  Thus, the prepreg 24 is composed of layers oriented at 0 °.

  Specifically, in the 0 ° layer of the prepreg 24a, the number of windings is set to be constant (for example, once) from the small diameter end of the shaft to the portion over the distance Ly, and thereafter, the distance from the small diameter end is Up to the position where Lx is reached, the number of windings is set so as to gradually decrease. On the other hand, the + 0 ° layer of the prepreg 24b is not arranged from the small diameter end of the shaft to the portion over the distance Ly, and thereafter, the number of windings rapidly increases until the position where the distance from the small diameter end becomes Lx. It is set so as to increase gradually, and the number of windings is set constant (for example, once) on the larger diameter side than the distance Lx. Eventually, the small-diameter end and the large-diameter end are set to have the same number of turns and an integer number.

  The 0 ° layer of the prepreg 24a gradually decreases gradually, and the portion where the 0 ° layer of the prepreg 24b gradually increases gradually joins the 0 ° layer of the prepreg 24a with the 0 ° layer of the prepreg 24b. It is.

  Further, the prepreg 24a and the prepreg 24b include carbon fibers having different elastic moduli. Specifically, the carbon fiber in the prepreg 24a (first straight layer) is the prepreg 24b (second straight). The difference in elastic modulus is set to 40 to 100 GPa than the carbon fiber in the layer).

  Thus, the carbon fiber in the prepreg 24a (first straight layer) has a difference in elastic modulus of 40 to 100 GPa, preferably 50 to 60 GPa, than the carbon fiber in the prepreg 24b (second straight layer). When set within the range, the obtained shaft can obtain an appropriate spin amount corresponding to the head speed and a stable launch angle.

  In addition, since the prepreg 24a and the prepreg 24b are disposed so as not to overlap each other, each prepreg 24a, 24b sufficiently exerts the effect of the elastic modulus of the carbon fiber that each comprises, As a result, the above effect can be obtained.

  Further, at this time, by arranging the first straight layer formed by the prepreg 24a in a portion extending at least from the small diameter end to 500 mm of the shaft, the effect of such carbon fibers can be more fully exhibited. In order to dispose the first straight layer in this way, the distance Lx may be set to at least 500 mm, but the distance Lx is preferably set to 850 mm.

  The second straight layer may be arranged on the larger diameter side than the first straight layer so as not to overlap the first straight layer.

  In general, a golf club shaft composed of a fiber reinforced resin layer is adjusted in length by cutting a small diameter end portion and a large diameter end portion after heat curing. The distance Lx mentioned here is set so that the length after cutting in this way is at least 500 mm. For example, at least Lx = 510 mm should be set for cutting the small diameter end portion by 10 mm, and at least Lx = 520 mm should be set for cutting the small diameter end portion by 20 mm. That is, each distance is based on after cutting.

  Moreover, it is preferable that the difference of the thickness of the prepreg 24a and the thickness of the prepreg 24b is the same. If there is a difference in thickness, a step is generated in the shaft, which is not preferable in terms of quality in terms of shaft formation.

  In each of the prepregs 21a and 21b, carbon fibers are used as reinforcing fibers. Carbon fiber is particularly excellent in specific strength and specific rigidity among light weight and high strength inorganic fibers. In order to obtain the effects of the present invention, it is preferable to use long fibers that are unidirectional materials as the carbon fibers.

  As the matrix resin constituting each of the prepregs 24a and 24b, a thermoplastic resin or a thermosetting resin can be used, but a thermosetting resin is preferably used.

As the thermoplastic resin, polyamide resins, polyacrylate resins, polystyrene resins, polyethylene resins, and mixed resins thereof can be used. On the other hand, as thermosetting resins, epoxy resins, unsaturated polyester resins, phenol resins, urea resins, melamine resins, diallyl phthalate resins, urethane resins, polyimide resins, and mixed resins thereof are used. Can be used. Among these, epoxy resins are most preferably used because they have a low cure shrinkage and high rigidity and toughness.
[Small diameter side straight layer]
The narrow-side straight layer is a layer composed of the prepreg 22 of the pattern 2 in FIG. 1 and is composed of a layer in which carbon fibers are oriented in the shaft axial direction.

  The small-diameter side straight layer includes a first small-diameter side straight layer formed from the prepreg 22a and a second small-diameter side straight layer formed from the prepreg 22b. The prepreg 22a has a small diameter of the shaft. Arranged on the end (left end in the figure) side, the prepreg 22b is arranged on the larger diameter side than the prepreg 22a. The prepreg 22a and the prepreg 22b are arranged such that their cut surfaces are abutted at the abutting portion 31 so as not to overlap each other, and the pattern 2 is formed.

  Specifically, the prepreg 22a is set so that the number of windings is constant (for example, once) from the small diameter end of the shaft to the distance La, and thereafter, the distance from the small diameter end is La + Lc. Until the position becomes, the number of windings is set to be gradually reduced. On the other hand, the prepreg 22b is not arranged from the small diameter end of the shaft to the portion extending over the distance La, and thereafter, the number of windings is set to gradually increase until the position where the distance from the small diameter end becomes La + Lc. ing. Thereafter, the number of windings is constant (for example, once) from the position of the distance La + Lc to the position of the distance La + Lc + Lb, and thereafter, the number of windings is set to gradually decrease until the position where the distance becomes La + Lc + Lb + Ld. .

  The portion where the prepreg 22a gradually decreases and the prepreg 22b gradually increases is the abutting portion 31 where the prepreg 22a and the prepreg 22b are abutted.

  The carbon fiber in the prepreg 22a (first small diameter straight layer) has an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more, and the prepreg 22b (second small diameter straight layer). The carbon fiber therein has an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more.

  Thus, since the prepreg 22a and the prepreg 22b are not overlapped, each prepreg 22a, 22b can fully exhibit the effect | action by the elasticity modulus and tensile elongation of the carbon fiber which each comprises.

  At this time, the first thin-diameter-side straight layer formed by the prepreg 22a is disposed at least on the portion extending from the thin-diameter end to 100 mm of the shaft, and the second thin-diameter-side straight formed by the prepreg 22b. By disposing the layer at least in a portion extending from 150 mm to 200 mm from the small-diameter end of the shaft, the effect of such carbon fibers can be more fully exhibited. In particular, by providing such a second small-diameter side straight layer, a high bending strength can be imparted to the shaft, and a golf club shaft with a very low probability of breakage can be obtained.

  Thus, in order to arrange the first small-diameter side straight layer and the second small-diameter side straight layer, the distance La + Lc is set to at least 100 mm, preferably the distance La is set to at least 100 mm. At the same time, the distance La is less than 150 mm, preferably the distance La + Lc is less than 150 mm, the distance La + Lc + Lb + Ld exceeds 200 mm, and preferably the distance La + Lc + Lb exceeds 200 mm.

  The distance Lc is very important for alleviating the concentration of bending stress at the time of hitting the ball. If the distance Lc is too short, the bending stress is likely to break due to the bending stress at the time of hitting. It gets too high. Therefore, the distance Lc is preferably 20 mm to 50 mm, and more preferably 30 mm to 40 mm. Further, the distance Ld is also important for relaxing the stress concentration, and is preferably 20 mm to 70 mm, more preferably 30 mm to 60 mm.

  The distance Lb is important for obtaining sufficient bending strength without significantly increasing the bending rigidity of the shaft. If the distance Lb is too short, it tends to break due to bending stress at the time of impact, and if too long, the distance of the shaft Mass becomes heavy. Therefore, the distance Lb is preferably 50 mm to 100 mm, and more preferably 70 to 80 mm. That is, it is preferable that the portion corresponding to the distance Lb (distance La + Lc to distance La + Lc + Lb) is a portion extending at least 150 mm to 200 mm from the small diameter end of the shaft.

  In addition, as described above, the shaft for a golf club usually composed of a fiber reinforced resin layer is adjusted by cutting the small-diameter end portion and the large-diameter end portion after heat curing. , After cutting.

  The carbon fiber in the prepreg 22a needs to have an elastic modulus of 350 GPa or more. If the elastic modulus is less than 350 GPa, sufficient bending rigidity cannot be obtained at the portion where the prepreg 22a is provided, so that the variation in hitting points becomes large. A preferable elastic modulus is 400 GPa or less. Further, the tensile elongation of the carbon fiber needs to be 1.2% or more. This is because if the tensile elongation is less than 1.2%, the probability of the shaft breaking during the deformation of the shaft at the time of hitting the ball becomes extremely high. A preferable tensile elongation is 3.0% or less.

  From such a viewpoint, as the carbon fiber, a PAN-based highly elastic carbon fiber using polyacrylonitrile fiber as a raw material is preferable.

  The thickness of the prepreg 22a is preferably 0.125 mm or less. If the thickness of the prepreg 22a exceeds 0.125 mm, the bending rigidity of the shaft where the prepreg 22a is provided becomes too high, and the feeling may deteriorate. Further, since the head toe down is suppressed too much, the ball is likely to hit below the center of the head, the launch angle is low, and the trajectory has a large amount of backspin, which easily leads to a loss of flight distance. A preferable thickness is 0.05 mm or more.

  The carbon fiber in the prepreg 22b needs to have an elastic modulus of 100 GPa or less. When the elastic modulus exceeds 100 GPa, the bending rigidity of the partial shaft provided with the prepreg 22b becomes too high, and the feeling may deteriorate. Further, since the head toe down is suppressed too much, the ball is likely to hit below the center of the head, the launch angle is low, and the trajectory has a large amount of backspin, which easily leads to a loss of flight distance. A preferable elastic modulus is 30 GPa or more. Further, the tensile elongation of the carbon fiber needs to be 1.2% or more, preferably 3.0% or less.

  From this point of view, pitch-based low-elasticity carbon fibers using pitch as a raw material are suitable as the carbon fibers.

  The thickness of the prepreg 22b is preferably 0.125 mm or less. If the thickness of the prepreg 22a is greater than 0.125 mm, the bending rigidity of the shaft where the prepreg 22b is provided becomes too high, and the feeling may deteriorate. Further, since the head toe down is suppressed too much, the ball is likely to hit below the center of the head, the launch angle is low, and the trajectory has a large amount of backspin, which easily leads to a loss of flight distance. A preferable thickness is 0.05 mm or more.

  As the matrix resin constituting the prepregs 22a and 22b, for example, the above-exemplified resins can be used, preferably a thermosetting resin, and most preferably an epoxy resin for the same reason.

  The golf club shaft of the present invention may have other layers as long as it has a specific bias layer and a specific straight layer as described above. For example, as in the illustrated example, a layer in which the bias layer and the above-described straight layer are sequentially formed from the inside and a plurality of other straight layers are further formed is preferable.

  In addition, another layer may be formed between the specific bias layer and the specific straight layer as described above, or the specific straight layer is formed outside the specific bias layer. Also good.

  Furthermore, in this example, the first straight layer and the second straight layer are abutted, and the first small-diameter side straight layer and the second small-diameter side straight layer are abutted, but they do not overlap. As long as it is, for example, it may be arranged with an interval inevitable in manufacturing.

  As described above, such a golf club shaft is a golf club shaft composed of a plurality of fiber reinforced resin layers, and the carbon fibers are oriented at +30 to + 70 ° with respect to the shaft axial direction. And a bias layer composed of a layer oriented at −30 to −70 °, and a straight layer in which carbon fibers are oriented in the shaft axis direction. The connecting straight layer includes a first straight layer disposed at least on a portion extending from the small diameter end to 500 mm of the golf club shaft, and a first diameter layer on a larger diameter side than the first straight layer. It consists of the 2nd straight layer arrange | positioned so that it may not overlap with a straight layer, and the difference of the elasticity modulus of the carbon fiber in a 1st straight layer and a 2nd straight layer is comprised by 40-100GPa .

The elastic modulus of the carbon fibers of the first straight layer and the second straight layer is 240 to 450 GPa, and the difference is 40 to 100 GPa. When the difference in elastic modulus of the carbon fiber is 40 GPa or less, as described in “Problems to be solved by the invention”, although the vertical and horizontal launch angles are stable, the backspin amount is large and the flight distance is sufficient. Is less effective, and if it is 100 GPa or more, the shaft may be bent at the joint between the first straight layer and the second straight layer during swinging, and the cause of breakage may be Become.
The straight layer includes a first thin-diameter-side straight layer disposed in a portion extending from at least the small-diameter end to 100 mm of the golf club shaft, and 150 mm to 200 mm from at least the small-diameter end of the golf club shaft. It consists of a second thin-diameter-side straight layer arranged so as not to overlap the first thin-diameter-side straight layer, and the carbon fiber in the first thin-diameter-side straight layer has an elastic modulus. The carbon fiber in the second thin-side straight layer has an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more.

  Therefore, it is possible to obtain an appropriate spin amount corresponding to the head speed and a stable launch angle, and the directionality is also stabilized. Further, since a high bending strength can be achieved at the same time, a golf club shaft with a very low probability of breakage can be obtained.

  The effect of the present invention is more fully exhibited when applied to a so-called wood golf club shaft having a length of 1041 mm to 1219 mm and a shaft mass of 40 g to 85 g.

The golf club shaft of the present invention is also suitable for combination with a large head. Examples of the large head include a large head having a volume of 380 cm ^{3 to} 460 cm ³ and an inertia moment of 3500 g · cm ^{2 to} 5900 g · cm ² . The golf club shaft of the present invention can reduce and stabilize the backspin amount even when such a large head is mounted, and the directionality is also stable.

  Next, the present invention will be described more specifically based on examples.

  The materials for the golf club shafts produced in the examples and comparative examples are shown below.

Prepreg A: Carbon fiber prepreg HRX350C125S (thickness 0.098 mm, manufactured by Mitsubishi Rayon Co., Ltd., carbon fiber elastic modulus 390 GPa, tensile elongation 1.2%)
Prepreg B: Carbon fiber prepreg E052AA-10N (thickness 0.109 mm, manufactured by Nippon Graphite Fiber Co., Ltd., carbon fiber elastic modulus 54 GPa, tensile elongation 2.0%)
Prepreg C: Carbon fiber prepreg MR350J050S (thickness 0.058 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg D: Carbon fiber prepreg MRX350C125R (thickness 0.106 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg E: Carbon fiber prepreg TR350C125S (thickness 0.103 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg F: Carbon fiber prepreg TR350C150S (thickness 0.127 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg G: Carbon fiber prepreg TR350C150S (thickness 0.127 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg H: Carbon fiber prepreg TR350E125S (thickness 0.113 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
(Example)
<Mandrel>
A mandrel 10 having the shape shown in FIG. 2 was prepared. The mandrel 10 is made of an iron cylinder and has an overall length L3. The outer diameter of the mandrel 10 gradually increases linearly from the small diameter end P1 to the position (switching point) P2 of the length L1. The outer diameter is constant from the point P2 to the large diameter end P3 having the length L2.

  The specific outer diameter, length, and taper degree of each part of the mandrel 10 according to the present embodiment are as follows.

  The outer diameter of the small diameter end P1 is 4.00 mm, the outer diameter of the switching point P2 is 13.50 mm, and the same outer diameter (13.50 mm) is from the switching point P2 to the large diameter end P3. The length L1 from the small diameter end P1 to the switching point P2 is 950 mm, and the length L2 from the switching point P2 to the large diameter end P3 is 550 mm. The overall length L3 of the mandrel 10 is 1500 mm. Further, the taper degree from the small diameter end P1 to the switching point P2 is set to 10.00 / 1000.

<Cutting and winding prepreg>
Various prepregs (prepregs A to H) were cut into shapes shown in patterns 1 to 7 in FIG.

  That is, in the pattern 1, the prepreg A cut to + 45 ° and the prepreg A cut to −45 ° with respect to the longitudinal direction of the shaft were bonded to each other so as to be substantially shifted by a half circumference.

  The total size of the prepreg bonded together was adjusted so that the total length was 1190 mm, the number of windings at the small diameter end was 5.5, and the number of windings at the large diameter end was 2.8.

  In pattern 2, the sizes of prepregs A and B are such that carbon fibers are oriented in the axial direction of the shaft, and La, Lb, Lc, and Ld in FIG. 3 are La = 110 mm, Lb = 80 mm, Lc = 30 mm, and Ld, respectively. = 60 mm, and the number of windings was adjusted to be 1 time. In addition, the prepreg A and the prepreg B of the pattern 2 in FIG. 3 are taped from the release paper pasted on one side of the prepreg A and the prepreg B with the cut surfaces of the prepreg A and the prepreg B being abutted at the abutting portion 31. Yes. The release paper and the tape are peeled after the prepreg A and the prepreg B of the pattern 2 are wound around a mandrel described later.

  In pattern 3, the size of the prepreg C was adjusted so that the carbon fibers were oriented in the axial direction of the shaft, the total length was 600 mm, and the number of windings was one.

  In the pattern 4, the prepreg D and the prepreg E, which are cut so that the orientation angle of the carbon fiber is 0 ° with respect to the shaft axis direction, are abutted at the abutting portion 30a so as not to overlap with each other. It is taped from the top of the release paper. The release paper and tape are peeled off after the prepreg D and prepreg E of this pattern 4 are wound around a mandrel of the subsequent operation.

  In patterns 5 to 6, the sizes of the prepregs F to G were adjusted so that the carbon fibers were oriented in the shaft axis direction, the total length was 1190 mm, and the number of windings was one.

  In pattern 7, the size of the prepreg H was adjusted so that the carbon fibers were oriented in the shaft axis direction and the outer diameter of the narrow end was about 8.70 mm.

  Note that the prepregs A to H shown in the patterns 1 to 7 in FIG. 3 correspond to the prepregs 21 to 27 shown in the patterns 1 to 7 in FIG. 1, respectively.

  Next, each cut prepreg was wound around the mandrel 10 in the order of patterns 1-7. As for winding, 20 mm from the narrow end of the mandrel was used as the winding end.

  Next, a polypropylene tape (not shown) having a thickness of 20 μm and a width of 30 mm was wound and fixed under the condition of a winding pitch of 2 mm, and a shaft base tube formed on the mandrel 10 was obtained.

<Hardening of resin and polishing of shaft surface>
The shaft base tube was put in a curing furnace and heated at 145 ° C. for 2 hours to cure the resin of the prepreg, and then the polypropylene tape and the mandrel 10 were removed.

  Each end of the obtained golf club shaft base tube was cut by 10 mm to a total length of 1170 mm.

  The cantilever flex of the shaft before polishing (the amount of deflection of the shaft small diameter end when the position of 920 mm from the small diameter end is fixed and a weight of 3 kg is hung on the position of 10 mm from the small diameter end of the shaft) was 134 mm. It was. Further, the outer diameter of the small diameter end of the golf club shaft blank before polishing was 8.77 mm, and the outer diameter of the large diameter end was 15.85 mm.

  The golf club shaft tube was polished with a cylindrical grinder so that the outer diameter of the narrow end was 8.50 mm and the cantilever flex was 124 mm, and the golf club shaft of the example was obtained. .

  The golf club shaft of the example has a mass of 73.0 g, a twist angle of the shaft (fixed at a position of 1035 mm from the shaft small diameter end, 138.5 kgf · The angle at which the shaft was twisted when a torque of mm was applied) was 3.3 degrees.

<Attaching the golf club head and grip>
A commercially available titanium golf club head for drivers (volume: 460 cm ³ , mass: 203 g, loft angle: 9.5 °) was attached to the small-diameter end with an epoxy resin adhesive on the golf club shaft of the example. Further, the end portion of the shaft having a large diameter was cut by 75 mm, and a commercially available rubber grip was attached to the shaft using a double-sided tape to produce the golf club of the example.

<Evaluation of hit ball>
The golf club of the example is hit with a golf ball six times using a golf trial hitting robot “SHOTROBO-IV” manufactured by Miyamae Co., Ltd., and measurement such as flight distance measurement is performed using “TRACKMAN” manufactured by ISG. The average value of the rotation axis is measured with 6 shots, with the flying ball direction set to 0 °, the rotation axis right direction (slice) as positive (+), and the rotation axis left direction (hook) as negative (-). By adding these values, a total value is calculated, and the total value is calculated by dividing the total number of hits (six times).

<3-point bending test>
The golf club shaft of the example is subjected to a three-point bending test in accordance with a three-point bending test method for a C-shaped shaft in “Golf Club Shaft Certification Criteria and Standard Confirmation Method” defined by the Product Safety Association. In addition, this time, the test of the load point position T (90 mm from the shaft small diameter end portion) and the load point position A (175 mm from the shaft small diameter end portion) in the “Golf Club Shaft Certification Criteria and Standard Confirmation Method” were each tested. Carry out books one by one. FIG. 4 shows an outline of this three-point bending strength test apparatus.

(Comparative example)
As shown in FIG. 6, a shaft was produced in the same manner as in the example except that the pattern 4 was cut into the same size as that of the example by using only the prepreg D. This comparative example corresponds to Example 1 of Patent Document 4.

  In the golf club using the golf club shaft of the example, the backspin amount can be stabilized at an appropriate value as compared with the comparative example, and as a result, a stable launch angle can be obtained, which is an ideal trajectory. And can achieve a flight distance. In the comparative example, although the vertical and horizontal launch angles are increased, the backspin amount is large, and therefore a sufficient flight distance cannot be obtained.

  In the golf club shafts in Examples and Comparative Examples, both the load point positions T and A greatly exceed the strength standard of SG (Product Safety Association) and have a high three-point bending strength.

  In the golf club shaft of the example, the backspin amount is reduced and stabilized, so that an increase in the average flight distance can be expected, and since it has a high three-point bending strength, the probability of breakage can be reduced.

21 Prepreg (bias layer)
22a Prepreg (first narrow-side straight layer)
22b Prepreg (second small diameter straight layer)
24a prepreg (first straight layer)
24b prepreg (second straight layer)
Pattern 4 stitched straight layer

Claims (5)

A golf club shaft comprising a plurality of carbon fiber reinforced resin layers,
A bias layer in which a layer in which carbon fibers are oriented at +30 to + 70 ° with respect to the shaft axis direction and a layer oriented at −30 to −70 ° are stacked;
Carbon fibers are oriented in the axial direction of the shaft, and two or more straight layers positioned over the entire length of the shaft;
The carbon fiber has a small-diameter side straight layer oriented in the shaft axial direction,
At least one of the straight layers positioned over the entire shaft is disposed on a portion extending from the narrow end to 850 mm of the shaft for the golf club, and the large diameter side of the first straight layer And a second straight layer disposed in a portion extending from the end of the golf shaft to the large diameter end of the golf shaft, and the elastic modulus of the carbon fiber in the first straight layer is 50 to 350 GPa, and the second straight The elastic modulus of the carbon fiber in the layer is 50 to 350 GPa, and the difference between the elastic modulus of the carbon fiber in the first straight layer and the elastic modulus of the carbon fiber in the second straight layer is 40 to 100 GPa,
A golf club characterized in that at least one of the straight layers located over the entire shaft is a fiber reinforced resin layer having reinforcing fibers that are not cut from the small diameter end to the large diameter end of the golf shaft. Shaft. 2. The golf club shaft according to claim 1, wherein the elastic modulus of the carbon fibers in the first straight layer <the elastic modulus of the carbon fibers in the second straight layer. 2. The golf club shaft according to claim 1, wherein the elastic modulus of the carbon fiber in the first straight layer> the elastic modulus of the carbon fiber in the second straight layer.   The thin-diameter-side straight layer includes a first thin-diameter-side straight layer disposed in a portion extending from at least a small-diameter end to 100 mm of the golf club shaft, and at least 150-mm to a small-diameter end of the golf club shaft. It consists of a second thin-diameter-side straight layer disposed so as not to overlap the first thin-diameter-side straight layer in a portion extending over 200 mm, and the carbon fibers in the first thin-diameter-side straight layer are The elastic modulus is 350 GPa or more, the tensile elongation is 1.2% or more, and the carbon fiber in the second small diameter straight layer has an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more. The golf club shaft according to claim 1.   The straight layer composed of the first straight layer and the second straight layer is disposed inside the straight layer composed of a fiber reinforced resin layer having reinforcing fibers that are not cut from the small diameter end to the large diameter end of the golf shaft. The golf club shaft according to any one of claims 1 to 4.