JP2011087799A - Golf club shaft - Google Patents

Abstract

In a golf club shaft composed of a plurality of fiber reinforced resin layers, the backspin amount is reduced and stabilized, and high bending strength is also imparted.
A first bias layer 21a disposed at least on a portion extending from a small diameter end to 200 mm of a shaft, and the first bias layer does not overlap with a larger diameter side than the first bias layer. The second bias layer 21b arranged in such a manner is provided, and the elastic modulus of the carbon fiber included in each layer is appropriately set. In addition, the first small diameter side straight layer 22a arranged at least in the portion extending from the small diameter end to 100 mm of the shaft, and the first small diameter side in the portion extending from 150 mm to 200 mm from at least the small diameter end of the shaft. A second narrow-side straight layer 22b arranged so as not to overlap the straight layer is provided, and carbon fibers having a specific elastic modulus and tensile elongation are used as the carbon fibers included in each layer.
[Selection] Figure 1

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, and an object of the present invention is to provide a golf club shaft that can reduce and stabilize the backspin amount and has high bending strength.

In order to achieve the above object, the present invention employs the following configuration.
(1) A golf club shaft composed of a plurality of fiber reinforced resin layers, in which carbon fibers are oriented at +30 to + 70 ° with respect to the shaft axial direction, and at −30 to −70 ° A bias layer in which oriented layers are laminated; and a narrow-side straight layer in which carbon fibers are oriented in the shaft axial direction, wherein the bias layer is at least a small-diameter end to 200 mm of the golf club shaft. And a second bias layer disposed on a larger diameter side than the first bias layer so as not to overlap the first bias layer. The elastic modulus of the carbon fiber in the first bias layer is at least 50 GPa greater than the elastic modulus of the carbon fiber in the second bias layer, and the narrow-side straight layer is at least on the golf club shaft. Fine The first thin diameter side straight layer disposed in a portion extending from the end to 100 mm, and the first thin diameter side straight layer in a portion extending from 150 mm to 200 mm from at least the small diameter end of the golf club shaft. The carbon fiber in the first narrow-side straight layer is arranged so as not to overlap, and the carbon fiber in the first narrow-side straight layer 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 narrow-side straight layer has a modulus of elasticity of 100 GPa or less and a tensile elongation of 1.2% or more. (2) The first shaft for golf clubs The shaft for golf clubs according to (1), wherein the thin-side straight layer has a thickness of 0.125 mm or less.
(3) The shaft for a golf club according to (1) or (2), wherein the second thin-side straight layer has a thickness of 0.125 mm or less.
(4) The golf club shaft according to any one of (1) to (3), wherein the bias layer is formed on an inner side than the narrow-side straight layer.

  According to the golf club shaft of the present invention, the backspin amount can be reduced and stabilized, and the bending strength is also high.

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. And a bias layer (first bias layer and second bias layer) and a narrow-side straight layer (first narrow-side straight layer and second layer). At least a small diameter side straight layer).
The bias layer is formed by laminating a layer in which carbon fibers are oriented at +30 to + 70 ° with respect to the shaft axial direction and a layer oriented at −30 to −70 °. In this example, the bias layer is formed from the prepreg 21. Specifically, the first bias layer is formed from the prepreg 21a, and the second bias layer is formed from the prepreg 21b. 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.

[Bias layer]
The bias layer is a layer composed of the prepreg 21 having the pattern 1 shown in FIG. 1, and includes a first bias layer formed from the prepreg 21a and a second bias layer formed from the prepreg portion 21b. In this example, the prepregs 21a and 21b are arranged such that the layer oriented at + 45 ° (+ 45 ° layer) and the layer oriented at −45 ° (−45 ° layer) are slightly displaced in the direction of arrow A. They are stacked and bonded to each other. In the figure, the distance indicated by the symbol α corresponds to “deviation”. In this example, when wound around the mandrel 10, the + 45 ° layer and the −45 ° layer are overlapped so as to be shifted by a half circumference.

  Among the prepregs 21, the prepreg 21 a corresponding to the first bias layer is disposed on the small diameter end (left end in the drawing) side of the shaft, and the prepreg 21 b corresponding to the second bias layer is larger in diameter than the prepreg 21 a. Placed on the side. The prepreg 21a and the prepreg 21b are arranged such that their cut surfaces are abutted at the abutting portions 30a and 30b so as not to overlap each other, and the pattern 1 is formed.

As described above, the prepreg 21 includes the + 45 ° layer and the −45 ° layer of the prepreg 21a, and the + 45 ° layer and the −45 ° layer of the prepreg 21b.
Specifically, the + 45 ° layer of the prepreg 21a is set so that the number of windings gradually decreases from the small diameter end of the shaft to the portion extending over the distance Lx, and thereafter, the distance from the small diameter end is set to Ly. Until the position becomes, the number of windings is set so as to decrease gradually. On the other hand, the + 45 ° layer of the prepreg 21b is not arranged from the small diameter end of the shaft to the portion extending over the distance Lx, and thereafter, the number of windings rapidly increases until the position where the distance from the small diameter end becomes Ly. It is set so as to gradually increase, and on the larger diameter side than the distance Ly, the number of windings is set to gradually increase after gradually decreasing. Eventually, the number of windings at the large diameter end is set to be smaller at the small diameter end and the large diameter end. Thus, when the number of windings on the small diameter end side is large, the torsional rigidity (torque) can be reduced. In this example, on the larger diameter side than the distance Ly, the number of windings is set to gradually increase after gradually decreasing, but may be constant after the number of windings gradually decreases.
Then, the + 45 ° layer of the prepreg 21a gradually decreases gradually, and the portion where the + 45 ° layer of the prepreg 21b increases suddenly is a butt portion 30a where the + 45 ° layer of the prepreg 21a and the + 45 ° layer of the prepreg 21b are abutted. And this abutting part 30a is formed so that it may become +45 degrees (angle of a cut surface with respect to a shaft axial direction) which is the same as the orientation angle of the carbon fiber of the layer to be abutted.

Similarly, the −45 ° layer of the prepreg 21a is set so that the number of windings gradually decreases from the small diameter end of the shaft to the portion extending over the distance Lx, and thereafter, the distance from the small diameter end is increased. Up to the position where Ly is set, the number of windings is set to be gradually decreased. On the other hand, the −45 ° layer of the prepreg 21b is not arranged from the small diameter end of the shaft to the portion extending over the distance Lx, and thereafter, the number of windings is abrupt until the position where the distance from the small diameter end becomes Ly. The number of windings is set to gradually increase after gradually decreasing on the larger diameter side than the distance Ly. Eventually, the number of windings at the large diameter end is set to be smaller at the small diameter end and the large diameter end. In this example, on the larger diameter side than the distance Ly, the number of windings is set to gradually increase and then gradually increase, but may be constant after the number of windings gradually decreases.
Then, the −45 ° layer of the prepreg 21a is gradually decreased, and the −45 ° layer of the prepreg 21a and the −45 ° layer of the prepreg 21b are abutted with each other at the portion where the −45 ° layer of the prepreg 21b is gradually increased. The abutting portion 30b is formed so as to be −45 ° (the angle of the cut surface with respect to the shaft axis direction), which is the same as the orientation angle of the carbon fibers of the abutted layers.

  The prepreg 21a and the prepreg 21b include carbon fibers having different elastic moduli. Specifically, the carbon fiber in the prepreg 21a (first bias layer) is the prepreg 21b (second bias). The elastic modulus is set to be at least 50 GPa larger than the carbon fiber in the layer).

Thus, the carbon fiber in the prepreg 21a (first bias layer) has a modulus of elasticity that is at least 50 GPa greater than that of the carbon fiber in the prepreg 21b (second bias layer), preferably within a range up to 250 GPa. When set, the resulting shaft is restrained from being deformed, especially bent and twisted, at the moment the ball is hit, resulting in stable directionality (launch angle), ball spin, and back. The amount of spin is also reduced and stabilized.
In addition, since the prepreg 21a and the prepreg 21b are arranged so as not to overlap each other, the prepregs 21a and 21b sufficiently exhibit 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 bias layer formed by the prepreg 21a in at least a portion extending from the small-diameter end to 200 mm of the shaft, the effect of such carbon fiber can be more fully exhibited. In order to dispose the first bias layer in this way, the distance Ly may be set to at least 200 mm, but preferably the distance Lx is at least 200 mm.

  The second bias layer may be disposed at least at a part on the larger diameter side than the first bias layer so as not to overlap the first bias layer. Preferably, the second bias layer is thicker as shown in the illustrated example. The first bias layer is preferably disposed over the entire length of the portion where the first bias layer is not disposed so as to extend to the radial end (right end in the drawing).

  Moreover, by making the angle of each butting part 30a, 30b and the orientation angle of the carbon fiber of the layer to be faced the same angle, the carbon fiber is not cut at each butting part 30a, 30b, and the prepreg 21a The prepreg 21b can be integrated. Therefore, the bending rigidity can be changed without reducing the strength of the shaft. In order to make the angle of each butted portion 30a, 30b and the orientation angle of the carbon fibers of the layers to be abutted the same angle, the distance Ly may be set appropriately according to the distance Lx.

  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 here is set so that the length after cutting in this way is at least 200 mm. For example, it is sufficient to set at least Lx = 210 mm when cutting the thin end portion by 10 mm, and at least Lx = 220 mm when cutting the thin end portion by 20 mm. That is, each distance is based on after cutting.

  The difference between the thickness of the prepreg 21a (the total thickness of the + 45 ° layer and the −45 ° layer) and the thickness of the prepreg 21b is preferably less than 0.05 mm. If it exceeds 0.05 mm, there is a tendency that the bending rigidity is greatly changed due to a difference in outer diameter, or breakage tends to occur due to stress concentration.

  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 21a and 21b, 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, the head toe-down is suppressed too much, and 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 larger 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, the head toe-down is suppressed too much, and 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 thermosetting resins, and most preferably epoxy resins for the same reason.

The golf club shaft of the present invention may have other layers as long as it has the specific bias layer and the specific straight layer as described above. For example, as in the illustrated example, a layer in which the above-described bias layer and straight layer are sequentially formed from the inside, and a plurality of other straight layers are further formed is preferable.
Further, 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 bias layer and the second bias 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 bias layer includes a first bias layer disposed at least in a portion extending from the small diameter end to 200 mm of the golf club shaft, and a first bias layer on a larger diameter side than the first bias layer. The second bias layer is arranged so as not to overlap with the carbon fiber, and the elastic modulus of the carbon fiber in the second bias layer is configured to be at least 50 GPa higher than that of the carbon fiber in the first bias layer. . 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, the deformation of the shaft at the moment of hitting the ball, particularly bending and twisting, can be suppressed as much as possible, the backspin amount can be reduced and stabilized, 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 HSX350C125S (thickness 0.098 mm, manufactured by Mitsubishi Rayon Co., Ltd., carbon fiber elastic modulus 450 GPa, tensile elongation 1.0%)
Prepreg B: 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 C: 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 D: Carbon fiber prepreg TR350C100S (thickness 0.084 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg E: Carbon fiber prepreg MR350C175S (thickness 0.141 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg F: Carbon fiber prepreg MR350C150S (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 MR350E125S (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 and the prepreg B that were cut so that the orientation angle of the carbon fiber was + 45 ° with respect to the shaft axis direction were butted together at the abutting portion 30a so as not to overlap. Similarly, the prepreg A and the prepreg B that were cut so that the orientation angle of the carbon fiber was −45 ° with respect to the shaft axis direction were abutted at the abutting portion 30b so as not to overlap. Then, when these were wound around the mandrel 10, they were attached so as to shift substantially half a circle.
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 addition, the sizes of the prepregs A and B in the pattern 1 were set such that Lx and Ly in FIG. 3 were Lx = 265 mm and Ly = 365 mm, respectively.

  In Pattern 2, for prepregs B and C, carbon fibers are oriented in the shaft axial direction, and La, Lb, Lc, and Ld in FIG. 3 are La = 110 mm, Lb = 80 mm, Lc = 30 mm, and Ld = 60 mm, respectively. And the number of windings was adjusted to be 1 time. In addition, the prepreg B and the prepreg C of the pattern 2 of FIG. Yes. The release paper and tape are peeled after the prepreg B and prepreg C of this pattern 2 are wound around a mandrel described later.

In Pattern 3, the size of the prepreg D 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 patterns 4 to 6, the sizes of the prepregs E 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 at the small diameter end when a position of 920 mm from the small diameter end is fixed and a weight of 3 kg is hung at a position of 10 mm from the small diameter end) is 142 mm. It was. Further, the outer diameter of the small diameter end of the golf club shaft base tube before polishing was 8.77 mm, and the outer diameter of the large diameter end was 15.41 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 150 mm, and the golf club shaft of the example was obtained. .

  The golf club shaft of the example has a mass of 61.2 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 3.5 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 clubs of the examples were hit with a golf ball six times using a golf trial hitting robot “SHOTROBO-IV” manufactured by Miyamae Co., Ltd., and measurements such as flight distance measurement were performed using “TRACKMAN” manufactured by ISG. The measured results are shown in Table 1. In Table 1, the average value of the rotation axis is defined as 0 ° for the flying ball direction, positive (+) for the right direction (slice) of the rotation axis, and negative (-) for the left direction (hook) of the rotation axis. The total value was calculated by adding the values measured in six hits, and the total was calculated by dividing the total by the number of hits (six times).

<3-point bending test>
The golf club shaft of the example was 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. It was carried out one by one. FIG. 4 shows an outline of this three-point bending strength test apparatus. The results of measuring the three-point bending strength of the shaft are shown in Table 2.

(Comparative example)
As shown in FIG. 5, a shaft was produced in the same manner as in the example except that the pattern 1 was cut into the same size as that of the example using only the prepreg B, and each evaluation was performed. The evaluation results are shown in Tables 1 and 2. This comparative example corresponds to Example 1 of Patent Document 4.

  As shown in Table 1, in the golf club using the golf club shaft of the example, the backspin amount was decreased as compared with the comparative example, and as a result, the average flight distance was large. In the comparative example, although the backspin amount is stable, the backspin amount is larger than that in the example, so that the average flight distance is lost.

  As shown in Table 2, 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. .

  As described above, in the golf club shaft of the example, the backspin amount is reduced, and the average flight distance can be expected to increase because the backspin amount is stable. Can be lowered.

21 Prepreg (bias layer)
21a prepreg (first bias layer)
21b Prepreg (second bias layer)
22 Prepreg (straight layer on the small diameter side)
22a prepreg (second narrow-side straight layer)
22b Prepreg (second small diameter straight layer)

Claims (4)

A golf club shaft comprising a plurality of 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;
The carbon fiber has a small-diameter side straight layer oriented in the shaft axial direction,
The bias layer includes a first bias layer disposed at least in a portion extending from the small diameter end to 200 mm of the golf club shaft, and the first bias layer on a larger diameter side than the first bias layer. And the elastic modulus of the carbon fiber in the first bias layer is at least 50 GPa than the elastic modulus of the carbon fiber in the second bias layer. big,
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. A golf club shaft comprising:   2. The golf club shaft according to claim 1, wherein the first thin diameter straight layer has a thickness of 0.125 mm or less.   3. The golf club shaft according to claim 1, wherein the second thin diameter side straight layer has a thickness of 0.125 mm or less.   The golf club shaft according to claim 1, wherein the bias layer is formed on an inner side than the narrow-side straight layer.

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