JP2000024150A - Golf club shaft made of fiber reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf club shaft made of fiber reinforced plastic which has high front end fracture strength and torsional strength, is light in weight and has the excellent durability and thread cutting strength dealing particularly with the impact off the centroid (sweat spot) of a club head. SOLUTION: This golf club shaft is constituted by laminating fiber reinforced plastic layers of at least >=2 layers of angle layers and straight layers. The torsional rigidity from the head side front end of the shaft within a range of 150 mm from the head side front end is >=5 N/m2 and the bending rigidity thereof is >=12 N/m2. In addition, the weight over the entire part of the shaft is <=55 g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club shaft made of fiber-reinforced plastic.

[0002]

2. Description of the Related Art In recent golf clubs, golf clubs using a fiber reinforced plastic golf club shaft are widely used because of their light weight and high strength.

Particularly, in order to be able to increase the speed of the club head at the time of swinging, a large-sized head having a large sweet spot has been used with an increase in length. For this reason, it is necessary to suppress an increase in the total weight of the golf club and an increase in the moment of inertia of the golf club at the time of swing, so that a further reduction in the weight of the golf club shaft is required.

In a golf club shaft made of fiber reinforced plastic reinforced with reinforcing fibers, from the viewpoint of mechanical properties, the reinforcing fibers have a length of ± (30 to 70 °) with respect to the longitudinal direction of the shaft.
And a straight layer in which the reinforcing fibers are oriented at -20 to 20 ° with respect to the longitudinal direction of the shaft, and the angle layer improves the torsional strength, The straight layer has the function of improving the bending strength. Note that the orientation angle of the reinforcing fibers with respect to the longitudinal direction of the shaft is referred to as the orientation angle of the reinforcing fibers. Further, the above-mentioned golf club shaft made of fiber-reinforced plastic,
A resin-impregnated fiber sheet (= prepreg) is wrapped around a mandrel several times and then heated and formed into a sheet wrap method, or a resin-impregnated filament is wrapped around a mandrel at a predetermined angle and then heated. Many are formed by the filament winding method.

Therefore, in order to further reduce the weight of the golf club shaft made of fiber reinforced plastic, it is necessary to partially or entirely reduce the thickness of the above-mentioned straight layer and angle layer. Simply reducing the layer thickness will degrade the mechanical properties of the shaft. For this purpose, various methods as described below have been proposed.

First, Japanese Utility Model Laid-Open Publication No. Sho 62-33872 discloses a golf club shaft made of a fiber reinforced plastic with an angle layer and a straight layer as means for improving the torsional rigidity and torsional strength of a golf club shaft made of a fiber reinforced plastic. In the outermost layer, a reinforcing layer composed of a fiber-reinforced plastic layer having a reinforcing fiber orientation angle of ± (35 ° to 55 °) and a thickness of 40 to 70 μm is further provided with a reinforcing layer having a length of 1/5 or more in the longitudinal direction of the shaft. The provision over the length is described. However, this method cannot sufficiently cope with the aspect of reducing the weight of the golf club shaft.

[0007] Japanese Patent Application Laid-Open No. 9-327536 discloses a fiber reinforced plastic layer in which an inner angle layer, an inner straight layer, an outer angle layer, and an outer straight layer are laminated in this order over the entire length of a golf club shaft. And by setting the thickness of the outer angle layer within the range of 0.04 to 0.1 mm,
It has torsional strength of 0 N ・ m ・ degree or more and weighs 30-45.
g of the lightweight golf club shaft and the outer angle layer have a fiber basis weight of 18 to 55 g / m ² and a thickness of 0.05.
It describes a golf club shaft molded using a prepreg of not more than mm.

[0008] Although the above golf club shaft can achieve the object of maintaining strength and reducing the weight, the outer angle layer is made of a thin prepreg for the purpose of reducing the weight, and over the entire length of the golf club shaft. Therefore, there is a manufacturing complexity for this.

Further, Japanese Patent Application Laid-Open No. 9-141754 discloses that
By providing a reinforcing layer made of a partial fiber reinforced plastic layer having carbon fiber having a tensile elasticity of 5 to 150 GPa as a reinforcing fiber at the head end portion of the golf club shaft, the golf club shaft can be pre-tuned. A method for providing excellent bending strength is described, and Japanese Patent Application Laid-Open No. H10-15129 discloses a method of devising a type of a reinforcing layer at a tip portion of a golf club shaft and an angle of a reinforcing fiber of the reinforcing layer. Thus, a method is described in which the bending rigidity at the tip of the head side of the golf club shaft is suppressed within the range of 5 to 15 N · m ² , and the excellent bending strength is maintained.

Any of the golf club shafts utilizing the above-mentioned means has a low bending rigidity and maintains and improves the bending strength in order to secure the feeling characteristics of the golf club shaft and the flexibility of the tip of the golf club shaft. It is intended.

In actual golf swings, however, there are many cases where the golf club hits with the club head deviating from the center of gravity (sweet spot) of the club head. Therefore, it is necessary to maintain and improve the torsional strength rather than the bending strength of the shaft. Is extremely important.

When the bending rigidity at the tip of the golf club shaft is partially reduced as compared with other portions, the bending strength can be maintained, but the cantilever bending test strength (= the grip portion of the golf club shaft with the club head fixed) (The strength of the bending test) is reduced.

[0013] Furthermore, in general, for advanced players and players with high swing speeds (so-called hard hitters),
If the rigidity of the tip portion of the golf club shaft is low, there is a disadvantage that the orbit of the club head becomes unstable due to a toe-down phenomenon during the swing.

Japanese Patent Application Laid-Open No. Hei 8-224809 discloses that a reinforcing bias layer (= angle layer) at the tip of the shaft on the head side is made of a fiber reinforced plastic layer using carbon fibers having high elastic modulus as reinforcing fibers. Thus, a golf club shaft composed of a fiber reinforced resin laminated tube having sufficient torsional strength, light weight, and efficiently reduced torsion is described.

However, carbon fibers having a high modulus of elasticity, such as pitch-based carbon fibers, are not suitable as reinforcing fibers for improving the torsional strength and the bending strength because of their particularly low compressive strength. In addition, the golf club shaft of the example product disclosed in the above-mentioned publication has a weight of 56 g or more, which is insufficient in terms of weight reduction.

As described above, according to the conventional technique, the torsion strength, the bending strength, and the actual hitting durability are high,
It has been difficult to make a golf club shaft made of a fiber-reinforced plastic as light as 5 g or less.

[0017]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a golf club shaft made of fiber reinforced plastic which has high breaking strength at the tip end and high torsional strength and achieves the object of being lightweight. In particular, it is an object of the present invention to provide a golf club shaft having excellent durability and threading strength that can cope with a hit when the golf club is hit outside the center of gravity (sweet spot) of the club head.

[0018]

The above objects can be attained by providing a fiber reinforced plastic golf club shaft of the present invention having the following structure. That is, the present invention relates to a golf club shaft obtained by laminating at least two fiber-reinforced plastic layers of an angle layer and a straight layer, wherein the shaft has a head-side tip to a point within 150 mm from the head-side tip. The golf club shaft is made of a fiber-reinforced plastic golf club shaft having a torsional rigidity of 5 N · m ² or more, a bending rigidity of 12 N · m ² or more, and a total weight of the shaft of 55 g or less.

In the fiber reinforced plastic golf club shaft according to the present invention having the above-described structure, the head side tip of the shaft is within a range of 300 mm from the head side tip and within 0.4 mm of the shaft surface. The orientation angle of the reinforcing fibers is ± (30 to 70) within the depth range of
°), it is preferable to provide a reinforcing layer comprising a fiber-reinforced plastic layer.

Further, the orientation angle of the reinforcing fibers is ± (30 to 30).
The reinforcing layer made of a fiber-reinforced plastic layer having a thickness of 70 °) is formed into a single layer or a composite layer of a prepreg having a thickness of 0.15 mm or less in which a carbon fiber sheet formed by uniformly aligning carbon fibers is impregnated with a resin. It is preferable that they are obtained.

Further, the orientation angle of the reinforcing fiber is ± (3
0 to 70 °), the reinforcing fiber in the reinforcing layer has a tensile modulus of elasticity of 35.
It is preferable to be made of carbon fiber of 0 GPa or less.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the fiber reinforced plastic golf club shaft of the present invention will be described below.

The fiber reinforced plastic golf club shaft of the present invention has at least two or more fiber reinforced plastic layers of an angle layer and a straight layer, and each of these fiber reinforced plastic layers is reinforced. Consists of fibers and matrix resin.

The fiber reinforced plastic layer forming the angle layer is a plastic layer in which the reinforcing fibers in the plastic layer are oriented ± (30 to 70 °) with respect to the longitudinal direction of the shaft, that is, the orientation of the reinforcing fibers. Angle is ± (30-7
0 °), and the straight layer is a plastic layer in which the reinforcing fibers in the plastic layer are oriented at −20 to 20 ° with respect to the longitudinal direction of the shaft, that is, the orientation angle of the reinforcing fibers is −. 20-20 ° plastic layer.

The reinforcing fibers in these fiber-reinforced plastic layers include glass fibers, carbon fibers, aramid fibers,
Boron fibers, silicon carbide fibers, alumina fibers, steel fibers and the like can be used. In particular, polyacrylonitrile-based carbon fiber is the most suitable because it becomes a fiber-reinforced plastic layer having excellent mechanical properties. In addition, a single type of reinforcing fiber may be used, or two or more types may be used in combination.

The matrix resin is not particularly limited.
Usually, an epoxy resin is used. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidylamine type epoxy resin, isocyanate modified epoxy resin, alicyclic epoxy Resins or the like may be used. These epoxy resins are
It can be used from liquid to solid. Further, a single type of epoxy resin or a blend of two or more types of epoxy resins may be used. In addition, a curing agent is often used in the epoxy resin.

The golf club shaft made of fiber-reinforced plastic according to the present invention comprises, as described above, an angle layer in which the reinforcing fibers are oriented ± (30 to 70 °) with respect to the longitudinal direction of the golf club shaft, and A straight layer oriented at -20 to 20 degrees with respect to the longitudinal direction, and the golf club shaft has a torsional rigidity of 5 Nm within a range of 150 mm from the head end to the head end. ² or more and bending stiffness of 1
The manufacturing method is not limited as long as it is ² N · m ² or more and the weight of the entire shaft is 55 g or less.

However, in order to reduce the weight of the golf club shaft by suppressing the resin content, a prepreg in which resin is impregnated into sheet-like reinforcing fibers obtained by pulling fibers in one direction is wound around a mandrel several times. It is preferable to use a sheet wrapping method of heating and forming the sheet.

The prepreg used in the sheet wrapping method has a resin content of 35% by weight or less in order to make the golf club shaft lightweight and maintain high strength.
It is preferable to use one having a weight of 33% by weight or less, so that the bending strength in the 0 ° direction of the fiber-reinforced plastic after curing is 1500 MPa or more and the bending strength in the 90 ° direction is 90 MPa or more. It is preferable to use a prepreg using carbon fibers having a tensile modulus of 400 GPa or less, more preferably 350 GPa or less as reinforcing fibers.

Examples of other molding methods include a filament winding method, a compression molding method using a mold or the like, an internal pressure molding method, an autoclave molding method, a vacuum back molding method, a tape wrapping molding method, and the like.

Generally, a golf club shaft made of fiber-reinforced plastic is formed by a golf club shaft having a head-side tip to
A range of about 25 to 75 mm from the head side tip inserts the golf club shaft into a hosel of a club head,
An outer diameter parallel portion for bonding is formed, and this portion is a portion having the smallest outer diameter within the entire length of the golf club shaft.

Since the hosel end of the club head becomes a portion where stress concentration is likely to occur due to its shape, breakage of the golf club shaft most often occurs near the hosel end. Therefore, in a lightweight golf club shaft,
Proper reinforcement of the vicinity of the hosel end is important for preventing breakage.

The golf club shaft made of fiber-reinforced plastic according to the present invention has a torsional rigidity of 5N · within a range of 150 mm from the head end of the shaft to the head end.
m ² or more, and the bending rigidity is 12 N · m ² or more, so that breakage near the hosel end of the club head is extremely effectively prevented.

The torsional stiffness can be calculated by the product of the shear modulus (lateral modulus) of each fiber-reinforced plastic layer forming the golf club shaft and the secondary moment of area. . The bending rigidity is
Similarly, by the product of the longitudinal elastic modulus and the second moment of area,
Similarly, it can be obtained by calculation. The second moment of area and the second moment of area can be calculated from the inner diameter of the golf club shaft and the thickness of each fiber-reinforced plastic layer forming the golf club shaft.

Tensile modulus 350 GPa with excellent strength properties
When the following carbon fibers are used as reinforcing fibers, in order to increase the torsional rigidity in particular, the torsional rigidity is the highest ± 45 °.
, An reinforcing layer consisting of an angle layer in which the reinforcing fibers are oriented at ± 45 ° with respect to the longitudinal direction of the golf club shaft. In order to further increase the secondary moment of area, it is effective to laminate the reinforcing layer composed of the above-mentioned angle layer so as to be located on the outer peripheral surface side of the golf club shaft, that is, on the shaft surface side.

Accordingly, by laminating a reinforcing layer composed of an angle layer having an orientation angle of ± 45 ° of the reinforcing fibers within a range of a depth of 0.4 mm or less from the surface of the golf club shaft, the torsional rigidity is extremely high. A high golf club shaft. It is most preferable that the orientation angle of the reinforcing fibers of the reinforcing layer composed of the angle layer positioned on the outer peripheral surface layer portion is ± 45 ° as described above, but ± 30 °
７０70 °) is sufficient.

Further, the above-mentioned reinforcing layer composed of an angle layer has a thickness obtained by impregnating a resin into a sheet in which carbon fibers are aligned in one direction, because of the ease of handling and the degree of freedom of design. 0.15mm or less prepreg ± θ °
It can be formed by a method of laminating and winding, or a method of laminating a prepreg cut so that the carbon fiber is at a certain angle alone, or laminating it to a thin base cloth made of glass fiber scrim cloth and winding it. .

The reinforcing layer consisting of the angle layer located on the surface side of the shaft effectively reinforces the vicinity of the hosel end of the club head and prevents the golf club shaft from increasing in weight. It is preferable to form it within a range of 300 mm from the head end.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific structure of the fiber reinforced plastic golf club shaft of the present invention will be described in more detail below with reference to examples, and various physical properties of the golf club shaft of the example product will be compared with those of a comparative example product. This will be described in comparison with various physical properties of the golf club shaft.

The prepregs used in the examples and comparative examples are obtained by impregnating a resin in a sheet in which carbon fibers are aligned in one direction, and are as shown in Tables 1 and 2 below. is there.

[0041]

[Table 1]

[0042]

[Table 2]

Example 1 Commercially available prepregs A to F manufactured by Mitsubishi Rayon Co., Ltd. shown in predetermined columns of Tables 1 and 2 were cut, and the outer diameter of the small-diameter tip portion was 5.15 mm and the outer diameter of the large-diameter tip portion was 13 mm. .75 mm, 1500 mm in length, and a large-diameter tip portion to a portion 600 mm from the large-diameter tip portion constitutes a parallel portion having an outer diameter of 13.75 mm, and a position 600 mm from the large-diameter tip portion to 900mm over the small diameter tip is 9.56 / 10
On the mandrel formed in the tapered portion of 00, the entire area excluding the small-diameter tip portion to a position 60 mm from the small-diameter tip portion and the large-diameter tip portion to a position 275 mm from the large-diameter tip portion. According to the procedures described in (1) to (3) below, a winding layer for a reinforcing layer, a winding layer for an angle layer, and a winding layer for a straight layer having a reinforcing fiber orientation angle of 90 ° were formed. .

(1) When the prepreg (A) is wound around the mandrel so that the fiber direction is 90 ° with respect to the radial center line of the mandrel, the small diameter side end (= the small diameter tip of the mandrel) From the part 60 mm) to the large-diameter side end (= 275 mm from the large-diameter tip of the mandrel) and cut into a substantially trapezoidal shape so that it can be wound in one layer.
This is wound around a mandrel, and the orientation angle of the reinforcing fibers is 90
° for the reinforcing layer.

(2) The prepreg (B) was wound on the reinforcing layer winding layer formed in (1) such that the fiber direction was + 45 ° with respect to the radial center line of the mandrel. Occasionally, it is cut into two layers at the small-diameter end and 1.9 layers at the large-diameter end so as to be wound.
Similarly, when the prepreg (B) is wound on the winding layer for the reinforcing layer similarly formed in (1), so that the fiber direction is −45 ° with respect to the radial center line of the mandrel. The two prepregs are cut so as to be wound into two layers at the small-diameter end and 1.9 layers at the large-diameter end, and these two prepregs are bonded so that their fiber directions are orthogonal to each other. After that, the bonded prepreg was wound on the reinforcing layer winding layer formed in (1), and the angle layer was wound.

(3) The prepregs (C) and (D) are oriented such that the fiber direction is at 0 ° to the radial center line of the mandrel, and the wrapping layer for the angle layer formed in (2) is formed. When wound up, it is cut into a substantially trapezoidal shape so as to be wound as one layer from the small diameter side end to the large diameter side end, and these two prepregs are prepreg (C), In the order of prepreg (D), winding was performed on the winding layer for the angle layer formed in (2), and winding for the straight layer was performed.

Subsequently, the winding layers for the first reinforcing layer, the winding layers for the second reinforcing layer, and the third reinforcing The winding layers for the layers were formed by winding sequentially.

(4) The prepreg (E) was wound on the straight layer winding layer formed in (3) so that the fiber direction was at 45 ° to the radial center line of the mandrel. Occasionally, two layers at the smaller diameter end, and thereafter, the winding gradually decreases, and 150 m from the smaller diameter end.
m at the position of m, then 250 from the narrow end
mm at the position of mm, that is,
It is cut into a substantially trapezoidal shape so that it can be wound up to a position of 250 mm from the small-diameter side end, wound on the straight layer winding layer formed in (3), and wound for the first reinforcing layer. Was.

(5) The prepreg (F) is wound such that the fiber direction is 0 ° with respect to the radial center line of the mandrel, and when the prepreg (F) is wound following the procedure of (4), ~ 1 over the length of 200 mm from the narrow end
Layer, then gently decreases and no longer winds at 300 mm from the narrow end, i.e., into a substantially trapezoidal shape that winds from the narrow end to the 300 mm position from the narrow end. It was cut and wound on the winding layer for the first reinforcing layer formed in (4) and the winding layer for the straight layer formed in (3), and was wound for the second reinforcing layer.

(6) The prepreg (F) is formed into a right-angled triangle having a fiber direction in the same direction as one of two sides sandwiching the right angle, and a length of the side sandwiching the right angle being 100 mm × 100 mm. This was cut so that the fiber direction was 0 ° with respect to the radial center line of the mandrel, and the fiber was wrapped in multiple layers at the small diameter side end, and thereafter the winding was gradually eliminated, ( Winding was performed on the winding layer for the second reinforcing layer formed in 5), and winding for the third reinforcing layer was performed.

Then, after wrapping a wrapping tape made of polypropylene, heating and curing in a curing furnace,
Removal from the mandrel, removal of the wrapping tape, and polishing of the outer peripheral surface are sequentially performed. Further, 10 mm is trimmed from the small-diameter side end and 10 mm is trimmed from the large-diameter side end, and the weight of the driver golf is 48 g and length is 1145 mm. I got a club shaft.

As the golf club shafts, ten prototypes of the same type, the same type, and the comparative example were manufactured. The above measured values and the measured values and test results described later are the average values of each of these 10 prototypes.

For every 25 mm from the head end of the golf club shaft to 300 mm from the head end,
When the torsional rigidity and the bending rigidity were obtained based on the thickness, longitudinal elastic modulus, and lateral elastic modulus of each fiber-reinforced plastic layer, the torsional rigidity was minimized at the head end, and the torsional rigidity at the position was It was 7.1 N · m ² . The flexural rigidity was minimized at a position 75 mm from the head end, and the flexural rigidity at this position was 14.2 N · m ² . Furthermore, from the surface of this golf club shaft, about 0.1
At the position at a depth of 3 mm, the first reinforcing layer composed of an angle layer in which the orientation angle of the reinforcing fibers was 45 ° could be observed.

Subsequently, the bending strength and torsional strength at the point T of the golf club shaft were measured according to the following methods. A destruction test of a golf club using this golf club shaft was also performed according to the following method. These results, along with the minimum value of the torsional rigidity and the minimum value of the bending rigidity of the golf club shaft,
It is shown in Table 3 below.

(1) Measurement of Three-Point Bending Strength (= T-Point Bending Strength) of Golf Club Shaft Head End Tip Certification Criteria for Golf Club Shafts Developed by the Japan Product Safety Association and Methods for Confirming Criteria (Five Products Approved by the Minister of International Trade and Industry) No. 2087
Of the golf club shaft at the position 90 mm from the head end of the golf club shaft (= point T) on October 4, 1993).

(2) Measurement of Torsional Strength of Golf Club Shaft The certification standard and the method of confirming the standard of the golf club shaft formulated by the Product Safety Association (Ministry of International Trade and Industry approval No. 5, No. 2087
(October 4, 1993).

(3) Breaking Test of Golf Club Bird Machine & Fabricatin
g Using an Air Cannon tester model GBC2a type manufactured by Company (Oregon, USA), 12.5 mm below and 25 mm outside the center of gravity of the club head.
The ball was hit at a position of mm (low / toe) at a ball speed of 60 m / s. 5 each at low / toe position
When the ball was not damaged by the hit of 00, 500 hits were made at a position (high heel) of 12.5 mm further inward of the center of gravity of the head by 25 mm. Low/
A case where the toe and the high heel did not break even when hit by 500 blasts was passed. The golf club for this test had a weight of 201 g, a loft angle of 11.5 °,
195cc volume manufactured by Concept Co., Ltd. (trade name Vesp)
o standard) club head, and the length of the golf club was 45 inches.

Example 2 In the golf club shaft of Example 1, except that the orientation angle of the reinforcing fibers of the first reinforcing layer was changed to 0 ° and the orientation angle of the reinforcing fibers of the third reinforcing layer was changed to 45 °, respectively. A golf club shaft having a configuration corresponding to that of Example 1 was obtained.

The weight of this golf club shaft is 48 g.
It is. Also, the tip of the head of the golf club shaft
The torsional stiffness and bending stiffness were determined based on the thickness, longitudinal elastic modulus, and transverse elastic modulus of each fiber reinforced plastic layer at intervals of 25 mm from the head end to 150 mm. The minimum was obtained at a position 50 mm from the tip, and the torsional rigidity at this position was 5.2 N · m ² . The bending stiffness was minimized at the head end, and the bending stiffness at this position was 17.9 N · m ² . Further, it was observed that the third reinforcing layer 18 μm, which is the outermost layer of the golf club shaft, formed an angle.

Comparative Example 1 A golf club shaft having a configuration corresponding to that of Example 1 was obtained except that the orientation angle of the reinforcing fibers of the first reinforcing layer in the golf club shaft of Example 1 was changed to 0 °.

The weight of this golf club shaft is 48 g.
It is. Also, the tip of the head of the golf club shaft
The torsional stiffness and bending stiffness were determined based on the thickness, longitudinal elastic modulus, and transverse elastic modulus of each fiber reinforced plastic layer at intervals of 25 mm from the head end to 150 mm. It was minimized at the tip, and the torsional rigidity at this position was 4.5 N · m ² . The bending stiffness was minimized at a position 75 mm from the head end, and the bending stiffness at this position was 19.0 N · m ² .

Comparative Example 2 A golf club shaft having a configuration corresponding to that of Example 1 was obtained, except that the orientation angle of the reinforcing fibers of the second reinforcing layer in the golf club shaft of Example 1 was changed to 45 °.

The weight of this golf club shaft is 48 g.
It is. Also, the tip of the head of the golf club shaft
The torsional stiffness and bending stiffness were determined based on the thickness, longitudinal elastic modulus, and transverse elastic modulus of each fiber reinforced plastic layer at intervals of 25 mm from the head end to 150 mm. It was minimized at the tip, and the torsional rigidity at that position was 8.5 N · m ² . The bending stiffness was minimized at a position 50 mm from the head end, and the bending stiffness at this position was 11.9 N · m ² .

[0064]

[Table 3]

[0065]

As described above in detail, the fiber reinforced plastic golf club shaft of the present invention has a torsional rigidity of 5 Nm within a range of 150 mm from the head end of the golf club shaft to the head end. ² or more, and the bending rigidity is 12 N · m ² or more, and the weight of the entire shaft is 55 g or less. Therefore, the shaft is lightweight and has excellent breakage strength at the tip and excellent torsional strength. It has characteristics, and particularly has excellent durability and threading strength that can cope with a hit when the club head deviates from the center of gravity (sweet spot) of the club head.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ikuro Takiguchi 4-1-1 Ushikawadori, Toyohashi-shi, Aichi F-term in the Toyohashi Works of Mitsubishi Rayon Co., Ltd. (reference) 2C002 AA05 CS03 MM02 MM06

Claims (4)

[Claims] 1. A golf club shaft comprising at least two fiber reinforced plastic layers, an angle layer and a straight layer, laminated on each other, wherein the golf club shaft has a length in a range from a head end of the shaft to 150 mm from the head end. The torsional rigidity is 5 N · m ² or more and the bending rigidity is 12
N · m ² or more, and the weight of the entire shaft is 5
A golf club shaft made of fiber-reinforced plastic weighing 5 g or less. 2. An orientation angle of the reinforcing fibers within a range of from the head end of the shaft to 300 mm from the head end and within a depth of 0.4 mm from the shaft surface is ± (30 to 30). The fiber reinforced plastic golf club shaft according to claim 1, further comprising a reinforcing layer made of a fiber reinforced plastic layer (70 °). 3. The reinforcing layer has a thickness of 0.15 in which a resin is impregnated in a carbon fiber sheet formed by aligning carbon fibers in one direction.
3. The golf club shaft made of a fiber-reinforced plastic according to claim 2, wherein a single layer or a composite layer of a prepreg having a thickness of not more than mm is molded. 4. 4. The golf club shaft made of a fiber-reinforced plastic according to claim 2, wherein the reinforcing fibers in the reinforcing layer are made of carbon fibers having a tensile modulus of 350 GPa or less.