Golf club shaft

Abstract

To provide a golf club shaft excellent in feeling and carry performance for a golfer having a relatively high head speed.SOLUTION: A shaft 6 has a tip end Tp and a bat end Bt. In the shaft 6, a flexural rigidity EI in a point separated from the tip end Tp at 130 mm is E1, a flexural rigidity EI in a point separated from the tip end Tp at 1,030 mm is E10, and a torsional rigidity GJ in a point separated from the tip end Tp at 130 mm is G1. A ratio (E10 / E1) is 2.4 or more and 8 or less. The flexural rigidity E1 is 2.5 (kgf m2) or less. The flexural rigidity E10 is 6.0 (kgf m2) or more. The torsional rigidity G1 is 0.5 (kgf m2) or more. A ratio (E1 / G1) is 1.0 or more and 4.0 or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to golf club shafts. [Background technology]

[0002] In a golf club shaft, physical properties such as bending rigidity and torsional rigidity may differ from part to part, and the performance of the shaft may change depending on the distribution of these physical properties.

[0003] Japanese Patent Laid-Open Publication No. 9-38254 discloses a golf club shaft in which the rigidity ratio GJ / EI, calculated by dividing the torsional rigidity GJ by the bending rigidity EI, increases by 0.1% or more per 10 mm toward the tip of the shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-38254 Summary of the Invention [Problem to be solved by the invention]

[0005] A shaft with excellent feel and distance performance is desirable. A shaft with good feel is easy to swing, resulting in a stable swing and good ball-hitting results. It has been found that shaft performance can be improved by newly designing the bending stiffness and torsional stiffness.

[0006] An example of the present disclosure provides a golf club shaft that provides excellent feel and distance performance for golfers with a relatively fast head speed. [Means for solving the problem]

[0007] In one embodiment, the golf club shaft has a tip end and a butt end. The bending stiffness EI at a point 130 mm away from the tip end is set to E1, the bending stiffness EI at a point 1030 mm away from the tip end is set to E10, and the torsional stiffness GJ at a point 130 mm away from the tip end is set to G1. The ratio (E10 / E1) is 2.4 or more and 8 or less. The bending stiffness E1 is 2.5 (kgf m 2 ) or less. The bending rigidity E10 is 6.0 (kgf m 2 ) or more. The torsional rigidity G1 is 0.5 (kgf m 2 ) or more. The ratio (E1 / G1) is 1.0 or more and 4.0 or less. [Effects of the Invention]

[0008] As one aspect, a golf club shaft that provides excellent feel and distance performance can be provided for golfers with a relatively fast head speed. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an overall view of a golf club equipped with a golf club shaft according to a first embodiment. [Figure 2] FIG. 2 is a development view of the golf club shaft of FIG. [Figure 3] FIG. 3 is a schematic diagram showing a method for measuring bending rigidity EI. [Figure 4] 4 is a graph in a Cartesian coordinate system in which the horizontal axis (x-axis) is the distance from the tip end (mm) and the vertical axis (y-axis) is the bending stiffness EI (kgf m2). This graph shows the EI distribution of Example 1. [Figure 5] FIG. 5 is a schematic diagram showing a method for measuring the torsional rigidity GJ. [Figure 6] FIG. 6 is a schematic diagram showing a method for measuring shaft torque. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate.

[0011] In this application, the terms "layer" and "sheet" are used. "Layer" is the name after being rolled, while "sheet" is the name before being rolled. A "layer" is formed by rolling a "sheet." In other words, the rolled "sheet" forms a "layer."

[0012] In this application, the same reference numerals are used for layers and sheets, for example, the layer formed by sheet s1 is referred to as layer s1.

[0013] In this application, the axial direction means the axial direction of the shaft. In this application, the circumferential direction means the circumferential direction of the shaft. Unless otherwise specified, the length in this application means the length in the axial direction. Unless otherwise specified, the position in this application means the position in the axial direction.

[0014] FIG. 1 shows a golf club 2 equipped with a golf club shaft 6 according to the present disclosure. The golf club 2 includes a head 4, a shaft 6, and a grip 8. The head 4 is provided at the tip portion of the shaft 6. The grip 8 is provided at the butt portion of the shaft 6. The shaft 6 is a shaft for a wood club. The golf club 2 is a driver (number 1 wood). The shaft 6 is a driver shaft.

[0015] The head 4 and the grip 8 are not limited. Examples of the head 4 include a wood type head, a utility type head, an iron type head, and a putter head. In this embodiment, the head 4 is a wood type head.

[0016] The shaft 6 is formed of a plurality of fiber-reinforced resin layers. The type of fiber is not limited. In this embodiment, carbon fiber-reinforced resin layers and glass fiber-reinforced resin layers are used as the fiber-reinforced resin layers. The shaft 6 is a tubular body. Although not shown, the shaft 6 has a hollow structure. The shaft 6 has a tip end Tp and a butt end Bt. In the golf club 2, the tip end Tp is located inside the head 4. In the golf club 2, the butt end Bt is located inside the grip 8.

[0017] 1, the double-headed arrow Ls indicates the length of the shaft 6. This distance Ls is measured along the axial direction.

[0018] The shaft 6 is formed by winding a plurality of prepreg sheets. In these prepreg sheets, the fibers are oriented substantially in one direction. A prepreg in which the fibers are oriented substantially in one direction is also called a UD prepreg. "UD" stands for unidirectional. Note that prepregs other than UD prepregs may also be used. For example, the fibers may be woven in the prepreg sheet. In this application, a prepreg sheet is also simply called a sheet.

[0019] A prepreg sheet includes fibers and a resin. The resin is also called a matrix resin. Examples of the fibers include carbon fibers and glass fibers. Typically, the matrix resin is a thermosetting resin.

[0020] Examples of the matrix resin of the prepreg sheet include thermosetting resins and thermoplastic resins. From the viewpoint of shaft strength, the matrix resin is preferably a thermosetting resin, and more preferably an epoxy resin.

[0021] The shaft 6 is manufactured by a sheet winding method. In the prepreg, the matrix resin is in a semi-cured state. In the shaft 6, a prepreg sheet is wound and cured. This curing means that the matrix resin in the semi-cured state is hardened. This curing is achieved by heating. The manufacturing process of the shaft 6 includes a heating step. This heating hardens the matrix resin of the prepreg sheet.

[0022] FIG. 2 is a development of prepreg sheets that make up the shaft 6. FIG. 2 shows the sheets that make up the shaft 6. The shaft 6 is made up of a plurality of sheets. In the embodiment of FIG. 2, the shaft 6 is made up of 14 sheets. The shaft 6 has a first sheet s1 to a fourteenth sheet s14. This development shows the sheets that make up the shaft in order from the inside in the radial direction of the shaft. The sheets are wound in order starting from the sheet located at the top in FIG. 2. In FIG. 2, the left-right direction of the drawing coincides with the axial direction. In FIG. 2, the right side of the drawing is the tip side of the shaft. In FIG. 2, the left side of the drawing is the butt side of the shaft.

[0023] 2 shows not only the winding order but also the axial arrangement. For example, in FIG. 2, one end of the sheet s1 is located at the tip end Tp.

[0024] The shaft 6 has a straight layer, a bias layer, and a hoop layer. Figure 2 shows the fiber orientation angle of each sheet. Sheets marked "0°" are straight sheets. The straight sheets make up the straight layer.

[0025] The straight layer is a layer in which the fiber orientation is essentially 0° relative to the axial direction. Due to errors during winding, etc., the fiber orientation may not usually be completely parallel to the shaft axis direction. In the straight layer, the absolute angle of the fibers relative to the shaft axis is 10° or less. The absolute angle is the absolute value of the angle (fiber angle) between the shaft axis and the fiber direction. In other words, an absolute angle of 10° or less means that the fiber angle is between -10 degrees and +10 degrees.

[0026] 2, the sheets constituting the straight layer (straight sheets) are sheet s1, sheet s6, sheet s7, sheet s8, sheet s9, sheet s11, sheet s12, sheet s13, and sheet s14. The straight layer greatly contributes to bending rigidity and bending strength.

[0027] The bias layer is a layer in which the fiber orientation is substantially inclined with respect to the axial direction. The bias layer greatly contributes to torsional rigidity and torsional strength. Preferably, the bias layer is formed of a pair of two sheets in which the fiber orientations are inclined in opposite directions. Preferably, this pair of sheets includes a layer with a fiber angle of -60° or more and -30° or less, and a layer with a fiber angle of 30° or more and 60° or less. That is, preferably, the bias layer has an absolute angle of 30° or more and 60° or less.

[0028] In the shaft 6, the sheets (bias sheets) that make up the bias layer are sheet s2, sheet s3, sheet s4, and sheet s5. Sheets s2 and s3 form a sheet pair (first sheet pair). Sheets s4 and s5 form a sheet pair (second sheet pair). Each sheet pair is wound in a state where it is stuck to each other. The shaft 6 includes multiple (two) sheet pairs.

[0029] Figure 2 lists the fiber angle for each sheet. The plus (+) and minus (-) in the fiber angle indicate the inclination direction of the fibers. Each sheet pair combines a sheet with a positive fiber angle and a sheet with a negative fiber angle. In each sheet pair, the fibers are inclined in opposite directions.

[0030] The hoop layer is a layer in which the fibers are arranged substantially along the circumferential direction of the shaft. Preferably, the absolute angle of the fibers in the hoop layer is substantially 90° with respect to the shaft axis. However, due to errors in winding, the orientation of the fibers may not be exactly 90° with respect to the shaft axis. Typically, the absolute angle of the fibers in this hoop layer is between 80° and 90°.

[0031] The hoop layer contributes significantly to the crushing rigidity and crushing strength of the shaft. Crushing rigidity is the rigidity against crushing deformation. Crushing deformation is deformation caused by a force that crushes the shaft inward in the radial direction. In a typical crushing deformation, the cross section of the shaft changes from a circular shape to an elliptical shape. Crushing strength is the strength against crushing deformation.

[0032] 2, the prepreg sheet (hoop sheet) for the hoop layer is sheet s10. The hoop layer s10 is sandwiched between straight layers s9 and s11.

[0033] A united sheet is used to manufacture the shaft 6 shown in Fig. 2. The united sheet is formed by laminating a plurality of sheets together.

[0034] In the embodiment of Figure 2, three sets of combined sheets are used. The first combined sheet is a combination of sheets s2 and s3. The second combined sheet is a combination of sheets s4 and s5. The third combined sheet is a combination of sheets s9 and s10.

[0035] As described above, in this application, sheets and layers are classified by the orientation angle of the fibers, and in addition, in this application, sheets and layers are classified by the length in the axial direction.

[0036] A layer arranged over the entire axial direction is referred to as a full-length layer. A sheet arranged over the entire axial direction is referred to as a full-length sheet. A rolled full-length sheet forms a full-length layer. On the other hand, a layer arranged partially over the axial direction is referred to as a partial layer. A sheet arranged partially over the axial direction is referred to as a partial sheet. A rolled partial sheet forms a partial layer.

[0037] A full length layer that is a bias layer is called a full length bias layer. A full length layer that is a straight layer is called a full length straight layer. A full length layer that is a hoop layer is called a full length hoop layer.

[0038] In the embodiment of FIG. 2, the full-length bias layers are sheets s2 and s3. The full-length straight layers are sheets s9, s11, s12, and s13. The shaft 6 has multiple full-length straight layers s9, s11, s12, and s13. The full-length hoop layer is sheet s10. The shaft 6 has the full-length hoop layer s10 sandwiched between the full-length straight layers s9 and s11.

[0039] A partial layer that is a bias layer is referred to as a partial bias layer. A partial layer that is a straight layer is referred to as a partial straight layer. A partial layer that is a hoop layer is referred to as a partial hoop layer.

[0040] In the embodiment of Fig. 2, the partial bias layers are sheets s4 and s5, the partial straight layers are sheets s1, s6, s7, s8 and s14, and no partial hoop layer is provided.

[0041] The sheets s4 and s5 are tip portion bias layers. The tip portion bias layers s4 and s5 are disposed at the tip portion of the shaft 6. One end of the tip portion bias layers s4 and s5 is located at the tip end Tp. The shaft 6 does not have a butt portion bias layer.

[0042] Sheets s1, s7, s8, and s14 constitute a tip partial straight layer. The tip partial straight layer is disposed at the tip portion of the shaft 6. One end of the tip partial straight layer is located at the tip end Tp.

[0043] The sheet s6 is a butt partial straight layer. The butt partial straight layer is disposed at the butt end of the shaft 6. One end of the butt partial straight layer is located at the butt end Bt.

[0044] The manufacturing process of this shaft 6 will be outlined below.

[0045] [Outline of shaft manufacturing process]

[0046] (1) Cutting process In the cutting process, the prepreg sheet is cut into a desired shape, resulting in the individual sheets shown in FIG.

[0047] The cutting may be performed by a cutting machine or manually, for example, by using a cutter knife.

[0048] (2) Bonding process In this step, a plurality of sheets are laminated together to produce the above-mentioned combined sheet. Heating and / or pressing may be used in the laminating step.

[0049] (3) Winding process In the winding process, a mandrel is prepared. Typically, the mandrel is made of metal. A release agent is applied to the mandrel. Then, a tacky resin, also known as a tacking resin, is applied to the mandrel. The cut sheet is wound around the mandrel. The tacking resin facilitates attachment of the sheet edge to the mandrel.

[0050] This winding process results in a wound body. In this wound body, the prepreg sheet is wound around the outside of the mandrel. This winding is performed, for example, by rolling the object to be wound on a flat surface. This winding may be performed manually or by machine. This machine is called a rolling machine.

[0051] (4) Tape wrapping process In the tape wrapping process, a tape is wound around the outer periphery of the wound body. This tape is also called wrapping tape. The wrapping tape is wound spirally without gaps while being tensioned. The wrapping tape applies pressure to the wound body. This pressure contributes to reducing voids.

[0052] (5)Curing process In the curing process, the wound body after tape wrapping is heated. This heating causes the matrix resin to harden. During this curing process, the matrix resin temporarily fluidizes. This fluidization of the matrix resin can expel air between or within the sheets. The clamping force of the wrapping tape promotes this air expulsion. As a result of this curing, a hardened laminate is obtained.

[0053] (6) Mandrel removal process and wrapping tape removal process After the curing step, the mandrel is removed and the wrapping tape is removed. Preferably, the mandrel is removed and the wrapping tape is removed.

[0054] (7) Both ends cutting process In this step, both ends of the cured laminate are cut to make the end faces of the tip end Tp and the butt end Bt flat.

[0055] (8) Polishing process In this process, the surface of the cured laminate is polished. The wrapping tape leaves spiral-shaped irregularities on the surface of the cured laminate. Polishing removes these irregularities, leaving a smooth surface.

[0056] (9) Painting process After the sanding step, the cured laminate is painted.

[0057] The shaft 6 has bending rigidity at each position in the axial direction. This bending rigidity (or its value) is also referred to as EI. In this application, the unit of EI is "kgf m 2 "

[0058] Figure 3 shows the method for measuring EI. An Intesco 2020 model universal testing machine (maximum load: 500 kg) can be used as the measurement device. The shaft 6 is supported from below by a first support point T1 and a second support point T2. While maintaining this support, a load F1 is applied from above to measurement point T3. The load F1 is applied vertically downward. The distance between points T1 and T2 is 200 mm. Measurement point T3 is located at a position that bisects the distance between points T1 and T2. The deflection amount H when load F1 is applied is measured. Load F1 is applied by an indenter D1. The tip of indenter D1 has a cylindrical surface with a radius of curvature of 5 mm. The downward movement speed of indenter D1 is 5 mm / min. When load F1 reaches 20 kgf (196 N), the movement of indenter D1 is stopped, and the deflection amount H at that point is measured. The deflection H is the displacement of point T3 in the vertical direction. EI is calculated using the following formula:

[0059] EI (kgf m 2 )=F1×L 3 / (48×H) where F1 is the maximum load (kgf), L is the distance between support points (m), and H is the amount of deflection (m). The maximum load F1 is 20 kgf, and the distance between support points L is 0.2 m.

[0060] The following 10 locations are examples of EI measurement points: (Measurement point 1): 130 mm away from the tip end Tp (Measurement point 2): 230 mm away from the tip end Tp (Measurement point 3): 330 mm away from the tip end Tp (Measurement point 4): 430 mm away from the tip end Tp (Measurement point 5): 530 mm away from the tip end Tp (Measurement point 6): 630 mm away from the tip end Tp (Measurement point 7): 730 mm away from the tip end Tp (Measurement point 8): 830 mm away from the tip end Tp (Measurement point 9): 930 mm away from the tip end Tp (Measurement point 10): 1030 mm away from the tip end Tp

[0061] The point 130 mm away from the tip end Tp is also referred to as point P1, which is also used as a reference symbol in the drawings (see FIG. 1).

[0062] At each measurement point, the distance from the tip end is measured along the axial direction, and these distances are measured from the tip end Tp toward the butt end Bt.

[0063] In this application, EI at the measurement point 1 is defined as E1. EI at the measurement point 2 is defined as E2. EI at the measurement point 3 is defined as E3. EI at the measurement point 4 is defined as E4. EI at the measurement point 5 is defined as E5. EI at the measurement point 6 is defined as E6. EI at the measurement point 7 is defined as E7. EI at the measurement point 8 is defined as E8. EI at the measurement point 9 is defined as E9. EI at the measurement point 10 is defined as E10. The units of E1 to E10 are kgf m 2 In determining the values ​​of E1 to E10, the numbers to the second decimal place may be rounded up or down.

[0064] In Fig. 4, the x-axis is the distance from the tip end (mm) and the y-axis is the bending stiffness (kgf m 2 4 is a graph showing the distribution of bending rigidity EI in Example 1, which will be described later. In this graph, the following 10 coordinate points (x, y) are plotted: ·Point(130,E1) ·Point(230,E2) ·Point(330,E3) Point (430,E4) ·Point(530,E5) ·Point(630,E6) ·Point(730,E7) ·Point(830,E8) ·Point(930,E9) ·Point(1030,E10)

[0065] For ease of explanation, point (130,E1) will also be referred to as point E1, point (230,E2) as point E2, point (330,E3) as point E3, point (430,E4) as point E4, point (530,E5) as point E5, point (630,E6) as point E6, point (730,E7) as point E7, point (830,E8) as point E8, point (930,E9) as point E9, and point (1030,E10) as point E10.

[0066] The shaft 6 has torsional rigidity at each position in the axial direction. This torsional rigidity (or its value) is also referred to as GJ. In this application, the unit of GJ is "kgf m 2 "

[0067] The measurement points for GJ are, for example, a point 90 mm away from the chip end Tp and a point 140 mm away from the chip end Tp. If GJ at the point 90 mm away from the chip end Tp is Ga, GJ at the point 140 mm away from the chip end Tp is Gb, and GJ at the point P1 130 mm away from the chip end Tp is G1, then G1 can be calculated by proportional calculation using the following formula. G1 = [(Gb-Ga) / 50] × 40 + Ga

[0068] Figure 5 shows the method for measuring the torsional rigidity GJ at the measurement point Pm. The first position is fixed by jig M1, and the second position, located S (m) away from jig M1, is held by jig M2. Jig M1 holds the shaft 6 at a width of 40 mm. The span S is adjusted depending on the measurement point. When measuring GJ at a point 90 mm away from the tip end Tp, the span S is set to 0.1 m (100 mm). When measuring GJ at a point 140 mm away from the tip end Tp, the span S is set to 0.2 m (200 mm). The measurement point Pm is the point that bisects the first and second positions. The torsional angle A of the shaft 6 is measured when a torque Tr of 0.139 (kgf m) is applied to the shaft 6 from jig M2. The torsional rigidity GJ is calculated using the following equation. GJ (kgf m 2 )=S×Tr / A where S is the measurement span (m), Tr is the torque (kgf m), and A is the twist angle (radian). The torque Tr is 0.139 (kgf m).

[0069] 6 is a schematic diagram showing a method for measuring shaft torque. The portion from a point 40 mm from the tip end Tp to the tip end Tp is fixed by a jig M1. This fixation is achieved by an air chuck, and the air pressure of this air chuck is 2.0 kgf / cm. 2Jig M2 is fixed to a 50 mm wide area 825 mm away from jig M1 on the butt end Bt side. This fixation is achieved by an air chuck, and the air pressure of this air chuck is 1.5 kgf / cm 2 Jig M2 is rotated while jig M1 is fixed, and a torque Tr of 0.139 kgf m is applied to shaft 6. The torsional angle caused by this torque Tr is the shaft torque. The smaller the shaft torque, the greater the torsional rigidity of shaft 6 as a whole.

[0070] Reducing the shaft torque increases the directional stability of the ball. The greater the flight distance, the greater the deviation of the ball in the left-right direction. Reducing the shaft torque is important for competitive golfers who seek greater flight distance. From this perspective, the shaft torque is preferably 4.0° or less, more preferably 3.9° or less, and even more preferably 3.8° or less. If there are too many bias layers, the shaft becomes heavy. From this perspective, the shaft torque is preferably 2.8° or more, more preferably 2.9° or more, and even more preferably 3.0° or more.

[0071] [E10 / E1, E1, E10] As described above, the bending stiffness E1 at point P1 130 mm away from the tip end Tp and the bending stiffness E10 at point 1030 mm away from the tip end Tp are measured. In a shaft with a large ratio of E10 to E1 (E10 / E1), the bending stiffness EI at the butt end of the shaft 6 is high, while the bending stiffness EI at the tip end of the shaft 6 is low.

[0072] A shaft with a large E10 / E1 ratio has high bending rigidity near the grip 8, providing a sense of solidity and improving feel. Flexibility also occurs at the tip of the shaft 6. As a result, the shaft 6 remains stable even with a strong swing, and the return of flex at the tip improves head speed. This shaft contributes to improved feel and increased distance, particularly for competitive golfers seeking a driver head speed of 40 m / s or more for greater distance.

[0073] The term "rebound" refers to the phenomenon in which the shaft returns to its original state, causing the head to lag behind in the direction of the swing. The return of the shaft during the downswing increases head speed.

[0074] In this way, increasing E10 / E1 improves the feel and enables the head to accelerate immediately before impact. From this perspective, E10 / E1 is preferably 2.4 or greater, more preferably 2.6 or greater, more preferably 2.8 or greater, more preferably 3.0 or greater, and even more preferably 3.2 or greater. If E10 / E1 is too large, the butt end of the shaft 6 may be too stiff, resulting in a poor feel, or the tip end of the shaft 6 may be too soft, resulting in insufficient recovery from flex. From this perspective, E10 / E1 is preferably 8.0 or less, more preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less.

[0075] In order to increase the flexure of the tip of the shaft 6 and increase the head speed due to the flexure recovery, the bending rigidity E1 is set to 2.5 (kgf m 2 ) or less is preferable, and 2.4 (kgf m 2 ) or less is more preferable, and 2.3 (kgf m 2 ) or less is more preferable. If E1 is too small, the bending recovery may be insufficient. From this point of view, the bending rigidity E1 should be 1.6 (kgf m 2 ) or more is preferable, and 1.8 (kgf m 2 ) or more is preferable, and 2.0 (kgf m 2 ) or higher is more preferable.

[0076] From the viewpoint of feeling and the flex of the tip of the shaft 6, E10 is 6.0 (kgf m 2 ) or more is preferable, and 6.2 (kgf m 2 ) or more is preferable, and 6.4 (kgf m 2 ) or more is preferable, and 6.6 (kgf m 2 ) or more is preferable, and 6.8 (kgf m 2) or more is more preferable. If E10 is too large, the butt end of the shaft 6 may be too hard, which may reduce the feel. From this perspective, E10 is set to 8.0 (kgf·m 2 ) or less is preferable, and 7.8 (kgf m 2 ) or less is more preferable, and 7.6 (kgf m 2 ) or less is more preferable.

[0077] 4, the values ​​of E1 to E10 increase as the distance from the chip end Tp increases. In this graph, the rate of change between two adjacent points is greatest between points E8 and E9.

[0078] E10 is greater than E9, and E9 is greater than E8. However, as shown in the graph in FIG. 4, a convex portion is formed near point E9. Point E9 is located above the line SL connecting points E8 and E10. The ratio [(E9-E8) / (E10-E9)] of the difference (E9-E8) to the difference (E10-E9) is greater than 1. Increasing the bending rigidity E9 further improves the firmness described above, resulting in a good feel. From this viewpoint, the ratio [(E9-E8) / (E10-E9)] is preferably 2.0 or greater, more preferably 2.5 or greater, and even more preferably 3.0 or greater. If E9 is excessively large, the feeling may be perceived as stiff, resulting in a poor feel. From this viewpoint, the ratio [(E9-E8) / (E10-E9)] is preferably 5.0 or less, more preferably 4.5 or less, and still more preferably 4.0 or less.

[0079] [G1] As described above, the torsional rigidity GJ at the point P1 130 mm away from the tip end Tp is set to G1.

[0080] Increasing G1 increases the torsional rigidity of the tip of the shaft 6. When the ball collides with the head at impact, the tip of the shaft 6 can twist in the direction that opens the face of the head 4. This phenomenon is also called "loose impact." Loose impact reduces the resilience and decreases the initial velocity of the ball. Reducing loose impact increases the resilience and improves the flight distance. From the perspective of reducing loose impact, G1 is set to 0.5 (kgf·m 2 ) or more is preferable, and 0.55 (kgf m 2 ) or more is more preferable, and 0.60 (kgf m 2 ) or more is preferable, and 0.65 (kgf m 2 ) or more is more preferable. If G1 is too large, the shot feeling may deteriorate. From this point of view, G1 is set to 0.85 (kgf m 2 ) or less is preferable, and 0.80 (kgf m 2 ) or less is more preferable, and 0.75 (kgf m 2 ) or less is more preferable.

[0081] [E1 / G1] E1 / G1 is the ratio of bending rigidity EI to torsional rigidity GJ at point P1. From the viewpoint of increasing head speed and suppressing impact loss due to flex return at the tip of shaft 6, E1 / G1 is preferably 4.0 or less, more preferably 3.7 or less, more preferably 3.3 or less, and even more preferably 3.1 or less. If E1 / G1 is too small, E1 may be too small and result in insufficient flex return, or G1 may be too large and result in a poor feel at impact. From this viewpoint, E1 / G1 is preferably 1.0 or more, more preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more.

[0082] As described above, the shaft 6 is formed of a plurality of fiber-reinforced resin layers, including a straight layer and a bias layer.

[0083] In the shaft 6, the total number of bias plies N1 at point P1, 130 mm away from the tip end Tp, is 3.5 or less. As shown in FIG. 2, the bias plies in the shaft 6 are ply s2, ply s3, ply s4, and ply s5. The total number of plies in these plies is 3.5 or less. At point P1, when the number of plies in ply s2 is p2, the number of plies in ply s3 is p3, the number of plies in ply s4 is p4, and the number of plies in ply s5 is p5, the total number of plies N1 is p2 + p3 + p4 + p5. The number of plies refers to the number of turns. For example, the number of plies in a ply wound two turns (720°) is 2.0. For example, the number of plies in a ply wound 1.5 turns (540°) is 1.5.

[0084] By providing the tip partial bias layers s4 and s5 and reducing the total number of plies N1, it is possible to reduce shaft torque while also achieving a lightweight club. From this perspective, the total number of plies N1 is preferably 3.5 plies or less, more preferably 3.4 plies or less, and even more preferably 3.3 plies or less. From the perspective of reducing shaft torque, the total number of plies N1 is preferably 2 plies or more, more preferably 2.2 plies or more, and even more preferably 2.4 plies or more. In Example 1 described below, the total number of plies N1 was 3.0 plies.

[0085] In shaft 6, the total thickness T1 of the bias layers at point P1, 130 mm away from the tip end Tp, is 0.23 mm or less. As shown in FIG. 2, the bias layers in shaft 6 are layers s2, s3, s4, and s5. The sum of the thicknesses of these layers is 0.23 mm or less. At point P1, if the thickness of layer s2 is t2, the thickness of layer s3 is t3, the thickness of layer s4 is t4, and the thickness of layer s5 is t5, then the total thickness T1 is t2 + t3 + t4 + t5. For example, if the thickness of the prepreg constituting layer s2 is R and the number of plies in layer s2 is 1.5, the thickness t2 of layer s2 is the product of these, i.e., 1.5 × R.

[0086] By providing the tip partial bias layers s4 and s5 and suppressing the total thickness T1, it is possible to reduce shaft torque while making the club lighter. From this viewpoint, the total thickness T1 is preferably 0.23 mm or less, more preferably 0.22 mm or less, and even more preferably 0.21 mm or less. From the viewpoint of reducing shaft torque, the total thickness T1 is preferably 0.13 mm or more, more preferably 0.14 mm or more, and even more preferably 0.16 mm. In Example 1 described below, the total thickness T1 was 0.20 mm.

[0087] 2, in the shaft 6, the straight layers include full-length straight layers s9, s11, s12, and s13 provided over the entire length of the shaft 6, tip partial straight layers s1, s7, s8, and s14 partially disposed in the tip portion of the shaft 6, and a butt partial straight layer s6 partially disposed in the butt end portion of the shaft 6. In the shaft 6, the bias layers include full-length bias layers s2 and s3 provided over the entire length of the shaft 6 and tip partial bias layers s4 and s5 partially disposed in the tip portion of the shaft 6.

[0088] In the shaft 6, one or more plies of the tip partial bias layer are arranged in a range from point P2, which is 200 mm from the tip end Tp, to the tip end Tp. That is, if the total number of plies of all the tip partial bias layers s4 and s5 is N2, N2 is 1.0 or more at any position in the range from point P2 to the tip end Tp.

[0089] The point 200 mm from the tip end Tp is also referred to as point P2, which is also used as a reference symbol in the drawings (see FIG. 1).

[0090] In the shaft 6, two or more plies of the tip partial straight layer are arranged in the range from a point 200 mm from the tip end Tp to the tip end Tp. That is, if the total number of plies of the tip partial straight layers s1, s7, s8, and s14 is N3, N3 is 2.0 or more at any position in the range from point P2 to the tip end Tp.

[0091] In the shaft 6, a butt partial straight layer s6 is disposed in a range extending from a point 300 mm from the butt end Bt to the butt end Bt. The range extending from a point 300 mm from the butt end Bt to the butt end Bt is also referred to as the butt specific region. The butt partial straight layer s6 exists at every position in the butt specific region. In FIG. 2, the axial length of the butt partial straight layer s6 is 300 mm or more.

[0092] The butt partial straight layer s6 suppresses unstable movement of the shaft 6 during the transition from the top of the swing to the downswing. The transition from the top of the swing to the downswing is when the butt partial straight layer s6 enhances a sense of solidity and improves the feel. The butt partial straight layer s6 stabilizes the behavior of the shaft 6 from the transition from the transition from the top of the swing to impact, improving maneuverability and maintaining a sense of solidity. From this perspective, the axial length of the butt partial straight layer s6 is preferably 300 mm or more, more preferably 310 mm or more, more preferably 320 mm or more, and still more preferably 330 mm or more. From the perspective of reducing the weight of the shaft, the axial length of the butt partial straight layer s6 is preferably 500 mm or less, more preferably 450 mm or less, and still more preferably 400 mm or less.

[0093] The shaft 6 has tip partial straight layers s1, s7, s8, and s14. Of these, the tip partial straight layer s1 has a fiber elastic modulus of 10 t / mm 2 In this way, in the shaft 6, the tip partial straight layer has a fiber elastic modulus of 10 t / mm 2 The low-elasticity tip partial straight layer s1 is the innermost layer of the shaft 6. The low-elasticity tip partial straight layer s1 does not have to be the innermost layer. The reinforcing fibers of the low-elasticity tip partial straight layer s1 are not limited, and examples include glass fiber and carbon fiber.

[0094] A low-elasticity tip straight reinforcement portion 20 is formed at the tip end of the shaft 6, in which two or more plies of low-elasticity tip partial straight layers s1 are arranged (see FIG. 2). The low-elasticity tip straight reinforcement portion 20 is formed in a range from the tip end Tp to a predetermined position. In FIG. 2, the double-headed arrow L1 indicates the length of the low-elasticity tip straight reinforcement portion 20. In this embodiment, the portion where two or more plies of the sheet s1 are wound is the low-elasticity tip straight reinforcement portion 20. As shown in FIG. 2, a hypotenuse s11 is formed on the butt side of the sheet s1, and the number of plies decreases toward the butt side. There is a boundary midway along this hypotenuse s11 where the number of plies of the sheet s1 becomes two or less.

[0095] The low-elasticity tip straight reinforcement portion 20 reduces the bending rigidity of the tip portion of the shaft 6. This ensures flexibility of the tip portion, potentially improving head speed. From this perspective, the length L1 of the low-elasticity tip straight reinforcement portion 20 is preferably 60 mm or more, more preferably 100 mm or more, and even more preferably 140 mm or more. From the perspective of reducing the weight of the shaft 6, the length L1 is preferably 300 mm or less, more preferably 250 mm or less, and even more preferably 200 mm or less.

[0096] The shaft 6 includes a high-elasticity tip partial bias layer. In the shaft 6, all of the tip partial bias layers s4 and s5 are high-elasticity tip partial bias layers. A part of the tip partial bias layer may be a high-elasticity tip partial bias layer. The fiber elastic modulus of the high-elasticity tip partial bias layer is 33 t / mm 2 That's all.

[0097] In order to reduce shaft torque, the fiber elasticity modulus of the high-elasticity tip partial bias layer is 33t / mm 2 More than 37t / mm is preferable. 2 More preferably, 40t / mm 2 From the viewpoint of the strength of the tip portion of the shaft 6, the fiber elastic modulus of the high-elasticity tip partial bias layer is 70 t / mm 2 Less than 60t / mm is preferable 2Less than 50t / mm is more preferable. 2 The following is more preferred:

[0098] A high-elasticity tip bias reinforcement portion 22 is formed at the tip end of the shaft 6, in which two or more plies of high-elasticity tip partial bias layers s4 and s5 are arranged (see FIG. 2). This number of plies is the total number of plies of all high-elasticity tip partial bias layers. In this embodiment, this number of plies is the total number of plies of the high-elasticity tip partial bias layer s4 and the high-elasticity tip partial bias layer s5. The high-elasticity tip bias reinforcement portion 22 is formed in a range from the tip end Tp to a predetermined position. In FIG. 2, the double-headed arrow L2 indicates the length of the high-elasticity tip bias reinforcement portion 22. In this embodiment, the portion where the total number of plies of the sheet s4 and the sheet s5 is two or more is the high-elasticity tip bias reinforcement portion 22. The sheets s4 and s5 are triangular, and the number of plies decreases toward the butt side. Therefore, at the predetermined position, there is a boundary where the total number of plies of the sheet s4 and the sheet s5 is less than two plies.

[0099] The high-elasticity tip bias reinforcement portion 22 can further reduce shaft torque while suppressing the bending rigidity of the tip portion of the shaft 6. From this viewpoint, the length L2 of the high-elasticity tip bias reinforcement portion 22 is preferably 50 mm or more, more preferably 75 mm or more, and even more preferably 100 mm or more. From the viewpoint of reducing the weight of the shaft 6, the length L2 is preferably 250 mm or less, more preferably 225 mm or less, and even more preferably 200 mm or less.

[0100] 2, the shaft 6 has a first tip partial straight layer s7 and a second tip partial straight layer s8 as tip partial straight layers that are longer than the tip partial bias layers s4 and s5. The second tip partial straight layer s8 is longer than the first tip partial straight layer s7. This configuration reduces stress concentration due to flexure at the tip end of the shaft 6, increasing the strength of the shaft 6.

[0101] The tip partial straight layer s7 is thin, 0.08 mm or less. Therefore, flexibility at the tip end of the shaft 6 is ensured. From the viewpoint of flexibility at the tip end, the thickness of the tip partial straight layer s7 is preferably 0.08 mm or less, more preferably 0.075 mm or less, and even more preferably 0.07 mm or less. From the viewpoint of strength, the thickness of the tip partial straight layer s7 is preferably 0.04 mm or more, and even more preferably 0.045 mm or less. above More preferably, 0.05 mm or less above It is more preferable that the number of plies of the layer s7 is substantially 1 regardless of the axial position. This "substantially" is preferably 0.95 or more and 1.05 or less. The fiber elastic modulus of the layer s7 is 24t / mm 2 Below (10t / mm 2 That's all.

[0102] The tip partial straight layer s8 is thin, 0.08 mm or less. Therefore, flexibility at the tip end of the shaft 6 is ensured. From the viewpoint of flexibility at the tip end, the thickness of the tip partial straight layer s8 is preferably 0.08 mm or less, more preferably 0.075 mm or less, and even more preferably 0.07 mm or less. From the viewpoint of strength, the thickness of the tip partial straight layer s8 is preferably 0.04 mm or more, and even more preferably 0.045 mm or less. above More preferably, 0.05 mm or less above It is more preferable that the number of plies of the layer s8 is substantially 1 regardless of the axial position. This "substantially" is preferably 0.95 or more and 1.05 or less. The fiber elastic modulus of the layer s8 is 24t / mm 2 Below (10t / mm 2 That's all.

[0103] The shaft 6 has a portion at its tip end that is both a low-elasticity tip straight reinforcement portion 20 and a high-elasticity tip bias reinforcement portion 22. In the shaft 6, the length L1 of the low-elasticity tip straight reinforcement portion 20 is greater than the length L2 of the high-elasticity tip bias reinforcement portion 22 (see FIG. 2). As a result, the length of the portion that is both a low-elasticity tip straight reinforcement portion 20 and a high-elasticity tip bias reinforcement portion 22 is L2. The length L1 may be shorter than the length L2. The length L1 may also be the same as the length L2.

[0104] The shaft 6 includes a high-elasticity butt partial straight layer. In the shaft 6, all of the butt partial straight layers s6 are high-elasticity butt partial straight layers. The shaft 6 may have a high-elasticity butt partial straight layer and a butt partial straight layer other than the high-elasticity butt partial straight layer. The fiber elastic modulus of the high-elasticity butt partial straight layer s6 is 33 t / mm 2 That's all.

[0105] From the viewpoint of the firmness and feel mentioned above, the fiber elasticity modulus of the high-elasticity butt straight layer is 33t / mm 2 More than 37t / mm is preferable. 2 More preferably, 40t / mm 2 From the viewpoint of the strength of the butt end portion of the shaft 6, the fiber elastic modulus of the high elasticity butt partial straight layer is 70 t / mm 2 Less than 60t / mm is preferable 2 Less than 50t / mm is more preferable. 2 The following is more preferred:

[0106] A high-elasticity butt straight reinforcement portion 24, in which one or more plies of high-elasticity butt partial straight layer s6 are arranged, is formed at the butt end of the shaft 6. The high-elasticity butt straight reinforcement portion 24 is formed in a range from the butt end Bt to a predetermined position. The double-headed arrow L3 in FIG. 2 indicates the length of the high-elasticity butt straight reinforcement portion 24. In this embodiment, the portion in which one or more plies of sheet s6 are wound is the high-elasticity butt straight reinforcement portion 24.

[0107] The high-elasticity butt straight reinforcement portion 24 can further enhance the solid feel described above, improving the feel. From this viewpoint, the length L3 of the high-elasticity butt straight reinforcement portion 24 is preferably 180 mm or more, more preferably 200 mm or more, and still more preferably 220 mm or more. From the viewpoint of reducing the weight of the shaft 6, the length L3 is preferably 400 mm or less, more preferably 350 mm or less, and still more preferably 300 mm or less.

[0108] From the standpoint of distance and feel, the shaft length Ls is preferably 1080 mm or more, more preferably 1130 mm or more, and still more preferably 1150 mm or more. Considering the restrictions on club length under the rules of golf, the shaft length Ls is preferably 1210 mm or less, more preferably 1200 mm or less, and still more preferably 1190 mm or less.

[0109] In order to increase the head speed, the shaft weight is preferably equal to or less than 64.0 g, more preferably equal to or less than 63.0 g, and still more preferably equal to or less than 62.0 g. In order to increase design freedom, the shaft weight is preferably equal to or greater than 55.0 g, more preferably equal to or greater than 56.0 g, and still more preferably equal to or greater than 57.0 g.

[0110] The following are examples of prepregs that can be used in the shafts of the present disclosure.

[0111] [Table 1]

[0112] [Table 2] [Example]

[0113] [Example 1] A shaft identical to shaft 6 was produced according to the manufacturing process described above. The sheet configuration of the shaft was as shown in Figure 2. The length Ls of the shaft was 1168 mm. The weight of the shaft was 59.0 g. A driver head and a grip were attached to the obtained shaft to obtain a golf club. The driver head used was the head attached to a "SRIXON ZX7 Driver (loft angle 10.5°)" manufactured by Sumitomo Rubber Industries, Ltd.

[0114] In Example 1, the high-elasticity tip partial bias layers s4 and s5 are made of a material having a fiber elastic modulus (tensile elastic modulus) of 40 t / mm 2 The prepreg used was a batt part straight layer s6, with a fiber modulus (tensile modulus) of 40t / mm 2 The prepreg was used. All layers except the tip straight layer s1 were carbon fiber reinforced layers, but the tip straight layer s1 was a glass fiber reinforced layer. This glass fiber reinforced layer had a fiber elastic modulus (tensile elastic modulus) of 7t / mm 2 Glass fiber reinforced prepreg was used.

[0115] In Example 1, the lengths L1 to L3 (see FIG. 2) were as follows. The length L1 of the low-elasticity tip straight reinforcement portion 20, in which two or more plies of the low-elasticity tip partial straight layer s1 were arranged, was 150 mm. The length L2 of the high-elasticity tip bias reinforcement portion 22, in which two or more plies of the high-elasticity tip partial bias layers s4, s5 were arranged, was 130 mm. The length L3 of the high-elasticity butt straight reinforcement portion 24, in which one or more plies of the high-elasticity butt partial straight layer s6 were arranged, was 250 mm.

[0116] As mentioned above, Figure 4 shows the EI distribution for Example 1. E1 is 2.15 (kgf m 2 ) E2 was 2.48 (kgf m 2 ) E3 was 2.85 (kgf m 2 ) E4 was 3.36 (kgf m 2 ) E5 was 3.90 (kgf m 2) was. E6 was 4.40 (kgf·m 2 ) was. E7 was 5.06 (kgf·m 2 ) was. E8 was 5.54 (kgf·m 2 ) was. E9 was 6.64 (kgf·m 2 ) was. E10 was 6.98 (kgf·m 2 ) was.

[0117] [Example 2-6 and Comparative Example 1] Golf clubs according to Example 2-6 and Comparative Example 1 were obtained in the same manner as in Example 1, except that the number of plies of the chip portion bias layers s4, s5 and the chip portion straight layers s1, s7, s8 was adjusted to the specifications shown in Table 3.

[0118] [Measurement of EI and GJ] EI and GJ were measured by the above method. The measured values are shown in Table 3 below.

[0119] [Measurement of Flight Distance] Five competitive golfers with a handicap of 0 to 10 and a head speed of 40 m / s or more with a driver hit 5 balls each with each club, and for each hit, the flight distance to the final landing point was measured. That is, this flight distance includes the run . each The average value of the data for each club is shown in Table 3 below.

[0120] [Feeling] In the above hits where the flight distance was measured, the feeling of the shaft was also judged. Each tester evaluated the feeling during the swing and the hit on a 5-point scale of 1 to 5. The higher the evaluation score, the better the feeling. As the golf ball, the product name "SRIXON Z-STAR XV" manufactured by Sumitomo Rubber Industries was used. The average value of this evaluation score is shown in Table 3 below.

[0121] [Table 3]

[0122] As shown in Table 3, the Examples were rated higher than the Comparative Examples.

[0123] The following notes are part of the inventions contained in this disclosure. [Appendix 1] It has a tip end and a butt end, The bending rigidity EI at a point 130 mm away from the tip end is E1, The bending rigidity EI at a point 1030 mm away from the tip end is E10, When the torsional rigidity GJ at a point 130 mm away from the tip end is G1, The ratio (E10 / E1) is 2.4 or more and 8 or less, The bending stiffness E1 is 2.5 (kgf m 2 ) or less, The bending stiffness E10 is 6.0 (kgf m 2 ) or more, The torsional rigidity G1 is 0.5 (kgf m 2 ) or more, A golf club shaft having a ratio (E1 / G1) of 1.0 or greater and 4.0 or less. [Appendix 2] the golf club shaft is formed of a plurality of fiber-reinforced resin layers, The plurality of fiber reinforced resin layers include a straight layer and a bias layer, The total number of plies of the bias layer at a point 130 mm away from the tip end is 3.5 plies or less, The total thickness of the bias layer at a point 130 mm away from the chip end is 0.23 mm or less, the straight layer includes a full-length straight layer provided over the full length of the shaft, a tip partial straight layer partially disposed at a tip end of the shaft, and a butt partial straight layer partially disposed at a butt end of the shaft, the bias layer includes a full length bias layer provided over the entire length of the shaft and a tip partial bias layer provided partially at a tip end portion of the shaft, Two or more plies of the tip partial straight layer are arranged in the range from a point 200 mm from the tip end to the tip end, One or more plies of the tip partial bias layer are arranged in a range from a point 200 mm from the tip end to the tip end, The butt partial straight layer is disposed in a range from a point 300 mm from the butt end to the butt end, 2. The golf club shaft of claim 1, wherein the shaft torque is 4° or less. [Appendix 3] The tip portion straight layer has a fiber elasticity modulus of 10t / mm 2 The low-elasticity tip includes a partial straight layer, which is: 3. The golf club shaft according to claim 2, wherein a low elastic tip straight reinforcing portion is formed at the tip portion of the shaft, in which two or more plies of the low elastic tip partial straight layer are arranged. [Appendix 4] The tip partial bias layer has a fiber elastic modulus of 33t / mm 2 The high-elasticity tip partial bias layer is 4. The golf club shaft according to claim 2, wherein a high-elasticity tip bias reinforcement portion is formed at a tip portion of the shaft, in which two or more plies of the high-elasticity tip partial bias layer are arranged. [Appendix 5] The batt portion straight layer has a fiber elastic modulus of 33t / mm 2 The high elasticity batt portion includes a straight layer, 5. The golf club shaft according to claim 2, wherein a high-elasticity butt straight reinforcement portion is formed at a rear end of the shaft, in which one or more plies of the high-elasticity butt partial straight layer are arranged. [Appendix 6] the tip partial straight layer includes a first tip partial straight layer that is longer than the tip partial bias layer and a second tip partial straight layer that is longer than the first tip partial straight layer, The thickness of the first tip partial straight layer is 0.08 mm or less, 6. The golf club shaft according to any one of claims 2 to 5, wherein the second tip partial straight layer has a thickness of 0.08 mm or less. [Appendix 7] The bending rigidity EI at a point 830 mm away from the tip end is E8, When the bending rigidity EI at a point 930 mm away from the tip end is E9, E9 is larger than E8, E10 is larger than E9, 7. The golf club shaft according to any one of claims 1 to 6, wherein the ratio [(E9-E8) / (E10-E9)] is greater than 1. [Explanation of symbols]

[0124] 2. Golf clubs 4 heads 6. Shaft 8. Grip 20 Low-elasticity tip straight reinforcement 22 High-elasticity chip bias reinforcement 24 High elasticity bat straight reinforcement part s1~s14: Prepreg sheets (layers) Bt...butt end Tp...Chip end

Claims

1. 1. A golf club shaft having a tip end and a butt end, The bending rigidity EI at a point 130 mm away from the tip end is E1, The bending rigidity EI at a point 1030 mm away from the tip end is E10, When the torsional rigidity GJ at a point 130 mm away from the tip end is G1, The ratio (E10 / E1) is 2.4 or more and 8 or less, The bending rigidity E1 is 2.5 (kgf m ２ ) or less, The bending rigidity E10 is 6.0 (kgf m ２ ) and above, The torsional rigidity G1 is 0.5 (kgf m ２ ) and above, The ratio (E1 / G1) is 1.0 or more and 4.0 or less, the golf club shaft is formed of a plurality of fiber-reinforced resin layers, The plurality of fiber reinforced resin layers include a straight layer and a bias layer, The total number of plies of the bias layer at a point 130 mm away from the tip end is 3.5 plies or less, The total thickness of the bias layer at a point 130 mm away from the tip end is 0.23 mm or less, the straight layer includes a full length straight layer provided over the full length of the golf club shaft, a tip partial straight layer partially disposed at the tip end of the golf club shaft, and a butt partial straight layer partially disposed at the butt end of the golf club shaft, the bias layer includes a full length bias layer provided over the full length of the golf club shaft and a tip partial bias layer provided partially at a tip end of the golf club shaft, Two or more plies of the tip partial straight layer are arranged in the range from a point 200 mm from the tip end to the tip end, One or more plies of the tip partial bias layer are arranged in a range from a point 200 mm from the tip end to the tip end, The golf club shaft has the butt partial straight layer disposed in a range from a point 300 mm from the butt end to the butt end.

2. 2. The golf club shaft according to claim 1, wherein the shaft torque is 4° or less.

3. The tip portion straight layer has a fiber elastic modulus of 10t / mm ２ The low-elasticity tip includes a partial straight layer, which is:

3. The golf club shaft according to claim 1, wherein a low elastic tip straight reinforcing portion is formed at the tip end of the golf club shaft, in which two or more plies of the low elastic tip partial straight layer are arranged.

4. The tip partial bias layer has a fiber elastic modulus of 33 t / mm ２ The high-elasticity tip partial bias layer is 4. The golf club shaft according to claim 1, wherein a high elasticity tip bias reinforcement portion is formed at a tip portion of the golf club shaft, in which two or more plies of the high elasticity tip partial bias layer are arranged.

5. The batt partial straight layer has a fiber elastic modulus of 33 t / mm ２ The high elasticity batt portion includes a straight layer, 5. The golf club shaft according to claim 1, wherein a high elasticity butt straight reinforcement portion is formed at a rear end of the golf club shaft, in which one or more plies of the high elasticity butt partial straight layer are arranged.

6. the tip partial straight layer includes a first tip partial straight layer that is longer than the tip partial bias layer and a second tip partial straight layer that is longer than the first tip partial straight layer, The thickness of the first tip partial straight layer is 0.08 mm or less, 6. The golf club shaft according to claim 1, wherein the second tip partial straight layer has a thickness of 0.08 mm or less.

7. The bending rigidity EI at a point 830 mm away from the tip end is E8, When the bending rigidity EI at a point 930 mm away from the tip end is E9, E9 is larger than E8, E10 is larger than E9, 7. The golf club shaft according to claim 1, wherein the ratio [(E9-E8) / (E10-E9)] is greater than 1.

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