Golf club shaft

Abstract

To provide a golf club shaft, composed of a plurality of fiber-reinforced resin layers, having a large weight, and exhibiting superior performance.SOLUTION: A shaft 6 is composed of a plurality of fiber-reinforced resin layers s1-s12. The shaft 6 includes a tip end Tp, a butt end Bt, a flexural rigidity E1 at a first point 290 mm away from the butt end Bt, and a flexural rigidity E2 at a second point 120 mm away from the butt end Bt. The flexural rigidity E2 is greater than the flexural rigidity E1. The flexural rigidity E1 is 5.0(kgf m2) or more and 6.1 (kgf m2) or less. The flexural rigidity E2 is 6.0(kgf m2) or more and 7.5(kgf m2) or less. The shaft 6 has a unit weight U1 of 1.15(g / cm) or more and 1.30(g / cm) or less per unit length. The shaft length Ls is 951 mm or more and 1017 mm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a golf club shaft. [Background technology]

[0002] Golf club shafts formed of multiple fiber-reinforced resin layers are known. An example of such a shaft is called a carbon shaft. Shafts with various specifications are designed.

[0003] JP 2008-5914 A discloses a golf club shaft whose shaft weight is 55g or more and 90g or less when converted to 46 inches, and whose average bending rigidity and shaft weight satisfy a predetermined relationship.JP Patent No. 6213063 A discloses a shaft whose shaft weight is 60g or more when converted to 1168mm, in which a hoop layer is disposed at a predetermined position, and in which the tensile modulus of the fibers in the hoop layer is 650GPa or more and 950GPa or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-5914 A [Patent Document 2] Patent No. 6213063 Summary of the Invention [Problem to be solved by the invention]

[0005] A golf club shaft formed from multiple fiber-reinforced resin layers is excellent in terms of lightness. On the other hand, there are cases where a heavy shaft is required. For example, a power hitter with a high head speed may require a heavy shaft. A steel shaft is relatively heavy, but has a small degree of freedom in design. It has been found that there is room for improvement in a heavy shaft of a given length formed from multiple fiber-reinforced resin layers.

[0006] One example of the present invention provides a heavy, high-performance golf club shaft formed from a plurality of fiber-reinforced resin layers. [Means for solving the problem]

[0007] In one embodiment, a golf club shaft is formed from a plurality of fiber-reinforced resin layers. The golf club shaft has a tip end, a butt end, a bending stiffness E1 at a first point 290 mm away from the butt end, and a bending stiffness E2 at a second point 120 mm away from the butt end. The bending stiffness E2 is greater than the bending stiffness E1. The bending stiffness E1 is 5.0 (kgf·m 2 ) or more 6.1 (kgf m 2 The bending stiffness E2 is 6.0 (kgf m 2 ) or more 7.5 (kgf m 2 The unit weight U1 per unit length of the entire shaft is 1.15 (g / cm) or more and 1.30 (g / cm) or less. The shaft length is 951 mm or more and 1017 mm or less. Effect of the Invention

[0008] As one aspect, a heavy, high-performance golf club shaft can be provided that is formed from a plurality of fiber-reinforced resin layers. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a golf club according to the first embodiment. [Diagram 2] FIG. 2 is an enlarged perspective view showing a head portion of the golf club of FIG. [Diagram 3] FIG. 3 is a perspective view of a golf club according to the second embodiment. [Figure 4] FIG. 4 is an enlarged perspective view showing a head portion of the golf club of FIG. [Diagram 5] FIG. 5 is a development view of the golf club shaft according to the first embodiment. [Figure 6]FIG. 6 is a development view of a golf club shaft according to the second embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a method for measuring bending rigidity. [Figure 8] FIG. 8(a) is a schematic diagram showing a method for measuring forward flex, and FIG. 8(b) is a schematic diagram showing a method for measuring reverse flex. [Figure 9] FIG. 9 is a schematic diagram showing a method for measuring the shaft torque. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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. A "layer" is the name after it has been rolled, whereas a "sheet" is the name before it has been 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, which coincides with the direction of the shaft axis, and the circumferential direction means the circumferential direction of the shaft.

[0014] FIG. 1 is a perspective view showing a golf club 2 equipped with a golf club shaft 6 according to the present invention. FIG. 2 is a partially enlarged view of FIG. 1. The golf club 2 includes a head 4, a shaft 6, and a grip 8. The head 4 is attached to a tip portion of the shaft 6. The grip 8 is attached to a butt portion of the shaft 6. The shaft 6 has a tip end Tp and a butt end Bt. The shaft 6 has a length Ls. The shaft length Ls is measured along the axial direction. The shaft length Ls is the distance from the tip end Tp to the butt end Bt. The golf club 2 is a hybrid club. The head 4 is a hybrid head.

[0015] The head 4 has a hitting face 4a, a crown 4b, and a sole 4c. The hitting face 4a is a curved surface. The hitting face 4a has a face bulge and a face roll.

[0016] Fig. 3 is a perspective view showing a golf club 10 equipped with a golf club shaft 6 according to the present invention. Fig. 4 is a partially enlarged view of Fig. 3. The golf club 10 includes a head 12, a shaft 6, and a grip 8. The head 12 is attached to a tip portion of the shaft 6. The grip 8 is attached to a butt portion of the shaft 6. The shaft 6 has a tip end Tp and a butt end Bt. The golf club 10 is a hybrid club. The head 12 is a hybrid head.

[0017] The head 12 has a hitting face 12a, a top blade 12b, and a sole 12c. The head 12 does not have a crown. The hitting face 12a is flat.

[0018] The head 4 and the head 12 are hybrid heads. The head 4 (FIG. 2) is a wood type hybrid head. The head 12 (FIG. 4) is an iron type hybrid head. The shaft 6 according to the present invention is preferably used in a hybrid club.

[0019] The shaft 6 is formed of a plurality of fiber reinforced resin layers. In this embodiment, carbon 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.

[0020] The shaft 6 is formed by winding a plurality of prepreg sheets. In these prepreg sheets, the fibers are substantially oriented in one direction. A prepreg in which the fibers are substantially oriented in one direction is also called a UD prepreg. "UD" is an abbreviation for unidirectional. Note that a prepreg other than a UD prepreg may be used. For example, the fibers may be woven in the prepreg sheet. In the present application, the prepreg sheet is also simply called a sheet.

[0021] The 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.

[0022] 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.

[0023] 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 cured. This curing is achieved by heating. The manufacturing process of the shaft 6 includes a heating step. This heating cures the matrix resin of the prepreg sheet.

[0024] FIG. 5 is a development of a prepreg sheet constituting the shaft 6 of the first embodiment. FIG. 5 shows the sheets constituting the shaft 6. The shaft 6 is composed of a plurality of sheets. In the embodiment of FIG. 5, the shaft 6 is composed of 12 sheets. The shaft 6 has a first sheet s1 to a twelfth sheet s12. This development shows the sheets constituting the shaft in order from the radially inner side of the shaft. The sheets are wound in order from the sheet located at the top in FIG. 5. In FIG. 5, the left-right direction of the drawing coincides with the axial direction. In FIG. 5, the right side of the drawing is the tip side of the shaft. In FIG. 5, the left side of the drawing is the butt side of the shaft. FIG. 5 shows not only the winding order but also the arrangement in the axial direction. For example, in FIG. 5, one end of the sheet s5 is located at the tip end Tp.

[0025] The shaft 6 has a straight layer and a bias layer. In Fig. 5, the orientation angle of the fibers of each sheet is shown. The sheet marked with "0°" is a straight sheet. The straight sheet constitutes the straight layer.

[0026] The straight layer is a layer in which the fiber orientation is substantially 0° with respect to the axial direction. Due to errors during winding, etc., the fiber orientation may not usually be completely parallel to the axial direction. In the straight layer, the absolute angle of the fibers with respect 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 -10° or more and +10° or less.

[0027] In the embodiment of FIG. 5, the sheets constituting the straight layer (straight sheets) are sheet s5, sheet s7, sheet s10, sheet s11, and sheet s12.

[0028] The bias layer is a layer in which the fiber orientation is substantially inclined with respect to the axial direction. Preferably, the bias layer is formed by two sheet pairs in which the fiber orientation is inclined in opposite directions. Preferably, the sheet pair 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, in the bias layer, the absolute angle is 30° or more and 60° or less. In this embodiment, the absolute angle of the fiber in the bias layer is substantially 45°. However, due to an error during winding, etc., the fiber orientation may not be completely 45° with respect to the shaft axial direction. When set to substantially 45°, the absolute angle of the fiber can be 40° or more and 50° or less. In FIG. 5, the sheet described as "+45°" or "-45°" is a bias sheet.

[0029] In the shaft 6, the sheets (bias sheets) constituting the bias layer are sheet s1, sheet s2, sheet s3, and sheet s4. Sheets s1 and s2 form a sheet pair (first sheet pair). Sheets s3 and s4 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.

[0030] In FIG. 2, the plus (+) and minus (-) in the fiber angle indicate the inclination direction of the fibers. In each sheet pair, a sheet with a positive fiber angle is combined with a sheet with a negative fiber angle. In each sheet pair, the fibers are inclined in opposite directions. In FIG. 5, sheet s2 is turned over and attached to sheet s1. As a result, the fibers of sheet s2 are inclined in the opposite direction to the fibers of sheet s1. The same is true for sheets s3 and s4.

[0031] The shaft 6 further includes a hoop layer. The hoop layer is a layer in which the fibers are arranged substantially along the circumferential direction of the shaft. Preferably, in the hoop layer, the absolute angle of the fibers is substantially 90° with respect to the shaft axis. However, due to errors during winding, the orientation of the fibers may not be completely 90° with respect to the shaft axis direction. Usually, in this hoop layer, the absolute angle of the fibers is 80° or more and 90° or less.

[0032] In the embodiment of FIG. 5, the prepreg sheets (hoop sheets) for the hoop layer are sheet s6, sheet s8 and sheet s9.

[0033] As described above, in this application, sheets and layers are classified according to the orientation angle of the fibers. In addition, in this application, sheets and layers are classified according to the length in the axial direction.

[0034] A layer disposed over the entire axial direction of the shaft 6 is referred to as a full-length layer. A sheet disposed over the entire axial direction of the shaft 6 is referred to as a full-length sheet. A wound full-length sheet forms a full-length layer. On the other hand, a layer disposed over a portion of the axial direction of the shaft 6 is referred to as a partial layer. A sheet disposed over a portion of the axial direction of the shaft 6 is referred to as a partial sheet. A wound partial sheet forms a partial layer.

[0035] 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.

[0036] In the embodiment of Fig. 5, the full length bias layers are sheets s1, s2, s3, and s4. The full length straight layers are sheets s7 and s10. The shaft 6 has a plurality of full length straight layers s7 and s10. The full length hoop layer is sheet s9. The shaft 6 has a full length hoop layer s9 sandwiched between the full length straight layers s7 and s10.

[0037] The full length hoop layer s9 is disposed over the entire specific butt region Tb.

[0038] 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.

[0039] In the embodiment of Fig. 5, no partial bias layer is provided. The partial straight layers are sheets s5, s11, and s12. The partial hoop layers are sheets s6 and s8. A plurality of partial hoop layers are provided.

[0040] The sheets s5, s11, and s12 are tip partial straight layers. The tip side ends of the tip partial straight layers s5, s11, and s12 are located at the tip end Tp of the shaft 6. The sheets s6 and s8 are butt partial hoop layers. The butt side ends of the butt partial hoop layers s6 and s8 are located at the butt end Bt of the shaft 6. The shaft 6 does not have a tip partial hoop layer whose tip side end is located at the tip end Tp. The shaft 6 does not have a butt partial straight layer whose butt side end is located at the butt end Bt. The axial length of the tip partial straight layer s5 is greater than half the shaft length Ls.

[0041] The tip partial straight layer s5 and the butt partial hoop layer s6 have an overlapping region R1 in the axial direction. The tip partial straight layer s5 and the butt partial hoop layer s8 have an overlapping region R2 in the axial direction.

[0042] The longest tip partial straight layer s5 is longer than half the shaft length Ls. The longest tip partial straight layer s5 does not reach the specific butt region Tb.

[0043] The axial length of the first butt partial hoop layer s6 is greater than half the shaft length Ls. The axial length of the second butt partial hoop layer s8 is greater than half the shaft length Ls.

[0044] The first butt partial hoop layer s6 is disposed over the entire specific butt region Tb. The second butt partial hoop layer s8 is disposed over the entire specific butt region Tb. All the hoop layers s6, s8, and s9 are disposed over the entire specific butt region Tb.

[0045] Fig. 6 is a development view of prepreg sheets constituting the shaft 16 of the second embodiment. Fig. 6 shows the sheets constituting the shaft 16. The shaft 16 is composed of a plurality of sheets. In the embodiment of Fig. 6, the shaft 16 is composed of eleven sheets. The shaft 16 has a first sheet s1 to an eleventh sheet s11.

[0046] The shaft 16 has a straight layer and a bias layer. In FIG. 6, the orientation angle of the fibers of each sheet is shown. The sheets marked with "0°" are straight sheets. The straight sheets constitute the straight layer. In the embodiment of FIG. 6, the sheets that constitute the straight layer (straight sheets) are sheet s4, sheet s6, sheet s9, sheet s10, and sheet s11.

[0047] The bias layer is a layer in which the orientation of fibers is substantially inclined with respect to the axial direction. In FIG. 6, the sheets marked with "+45°" or "-45°" are bias sheets. In the shaft 16, the sheets (bias sheets) constituting the bias layer are sheet s1, sheet s2, sheet s3, and sheet s5. Sheets s1 and s2 form a sheet pair (first sheet pair). Sheets s3 and s5 form a sheet pair (second sheet pair). Each sheet pair is wound in a state of being stuck together. The shaft 16 includes a plurality (two) of sheet pairs.

[0048] The shaft 16 further includes a hoop layer. The hoop layer is a layer in which the fibers are arranged substantially along the circumferential direction of the shaft. Preferably, in the hoop layer, the absolute angle of the fibers is substantially 90° with respect to the shaft axis. However, due to errors during winding, the orientation of the fibers may not be completely 90° with respect to the shaft axis direction. Usually, in this hoop layer, the absolute angle of the fibers is 80° or more and 90° or less.

[0049] In the embodiment of FIG. 6, the prepreg sheets (hoop sheets) for the hoop layer are sheet s7 and sheet s8.

[0050] In the embodiment of Fig. 6, the full length bias layers are sheet s1, sheet s2, sheet s3, and sheet s5. The full length straight layer is sheet s9. The shaft 16 has a full length straight layer s9. The full length straight layer s9 is only one layer. The shaft 16 has a full length hoop layer s8. The full length hoop layer s8 is only one layer.

[0051] In the embodiment of Fig. 6, the partial bias layer is not provided. The partial straight layers are sheet s6, sheet s10, and sheet s11. The partial hoop layer is sheet s7. There is only one partial hoop layer s7.

[0052] The sheets s6, s10, and s11 are tip partial straight layers. The tip side ends of the tip partial straight layers s6, s10, and s11 are located at the tip end Tp of the shaft 16. The sheet s7 is a butt partial hoop layer. The butt side end of the butt partial hoop layer s7 is located at the butt end Bt of the shaft 16. The shaft 16 does not have a tip partial hoop layer. The shaft 16 does not have a butt partial straight layer. The axial length of the tip partial straight layer s6 is greater than half the shaft length Ls. The longest tip partial straight layer s6 does not reach the specific butt region Tb.

[0053] The tip partial straight layer s6 and the butt partial hoop layer s7 have an overlapping region R1 in the axial direction. The axial length of the butt partial hoop layer s7 is greater than half the shaft length Ls.

[0054] The butt partial hoop layer s7 is disposed over the entire specific butt region Tb. All the hoop layers s7 and s8 are disposed over the entire specific butt region Tb.

[0055] The manufacturing process for the shafts 6 and 16 will now be outlined.

[0056] [Outline of shaft manufacturing process]

[0057] (1) Cutting process In the cutting process, the prepreg sheet is cut into a desired shape. Through this process, each sheet as shown in FIG. 5 or FIG. 6 is cut out.

[0058] The cutting may be performed by a cutting machine or manually, for example, by using a utility knife.

[0059] (2) Bonding process In this step, multiple sheets are laminated together as necessary. A pair of sheets constituting a bias sheet are laminated together. If a hoop sheet is difficult to roll by itself, the hoop sheet is laminated to another sheet. Heating and / or pressing may be used in the lamination step.

[0060] (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. A tacky resin is then applied to the mandrel. The resin is also called a tacking resin. The cut sheet is then wound around the mandrel. The tacking resin facilitates attachment of the sheet end to the mandrel.

[0061] The sheet is wound around the mandrel. This winding process results in a winding, in which the sheet is wrapped around the outside of the mandrel. This winding can be done manually or by machine, which is called a rolling machine.

[0062] (4) Tape wrapping process In the tape wrapping process, a tape is wrapped around the outer circumferential surface of the wound body. This tape is also called wrapping tape. This wrapping tape is wound in a spiral shape without gaps while being tensioned. This wrapping tape applies pressure to the wound body.

[0063] (5) Curing process In the curing process, the wound body after the tape wrapping is heated. This heating causes the matrix resin to harden. During this curing process, the matrix resin temporarily becomes fluid. This fluidization of the matrix resin can cause air to be expelled between or within the sheets. The tightening force of the wrapping tape promotes the expulsion of this air.

[0064] (6) Mandrel removal process and wrapping tape removal process After the curing step, the mandrel is removed and the wrapping tape is removed, preferably after the mandrel is removed, resulting in a cured laminate.

[0065] (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.

[0066] (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 and makes the surface smooth.

[0067] (9) Painting process After the sanding step, the cured laminate is painted.

[0068] As shown in Figures 1 and 3, the shaft 6, 16 has a first point P1 and a second point P2. The first point P1 is a point 290 mm away from the butt end Bt. This 290 mm is measured along the axial direction. The second point P2 is a point 120 mm away from the butt end Bt. This 120 mm is measured along the axial direction.

[0069] The bending stiffness is measured at the first point P1 and the second point P2. The bending stiffness at the first point P1 is defined as E1. The bending stiffness at the second point P2 is defined as E2. The units of bending stiffness E1 and bending stiffness E2 are kgf m 2 "

[0070] The area from the first point P1 to the second point P2 is defined as a specific butt area Tb. As shown in Fig. 1 and Fig. 3, the axial length of the specific butt area Tb is 170 mm.

[0071] FIG. 7 shows a method for measuring bending stiffness. A universal material testing machine, model 2020 (maximum load 500 kg), manufactured by Intesco, can be used as a measuring 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 a measurement point T3. The direction of the load F1 is vertically downward. The distance between points T1 and T2 is 200 mm. The position of the measurement point T3 is a position that bisects the distance between points T1 and T2. The deflection amount H when the load F1 is applied is measured. The load F1 is applied by an indenter D1. The tip of the indenter D1 is a cylindrical surface with a radius of curvature of 5 mm. The downward movement speed of the indenter D1 is 5 mm / min. When the load F1 reaches 20 kgf (196 N), the movement of the indenter D1 is stopped, and the deflection amount H at that time is measured. The deflection H is the displacement of point T3 in the vertical direction. The bending stiffness EI is calculated using the following formula.

[0072] EI(kgf m 2 )=F1×L3 / (48×H) Here, F1 is the maximum load (kgf), L is the distance between the support points (m), and H is the amount of deflection (m). The maximum load F1 is 20kgf, and the distance between the support points L is 0.2m.

[0073] The bending stiffness E1 is the EI when the measurement point T3 is the first point P1. The bending stiffness E2 is the EI when the measurement point T3 is the second point P2.

[0074] The shaft length Ls may preferably be 951 mm or more and 1017 mm or less. The shaft length Ls may be 951 mm or more, further 956 mm or more, and further 961 mm or more. The shaft length Ls may be 1017 mm or less, further 1012 mm or less, and further 1007 mm or less. This length is an intermediate length between a wood club and an iron club (hereinafter also referred to as an intermediate length). This length is excellent in suitability for a hybrid club. This length may be applied to a wood club or an iron club.

[0075] Regarding the shaft weight, the weight per unit length may be 1.15 (g / cm) or more and 1.30 (g / cm) or less. This weight is also called U1. The unit weight U1 is the weight per unit length (1 cm) of the entire shaft. The unit weight U1 may be calculated by dividing the entire shaft weight W1 (g) by the shaft length Ls (mm) and multiplying by 10. When a power hitter uses a shaft of medium length, a shaft of normal weight is too light, making it difficult to time the impact and resulting in a poor feeling. From the viewpoint of ease of swing for a power hitter, the unit weight U1 may be 1.15 (g / cm) or more, further 1.16 (g / cm) or more, and further 1.17 (g / cm) or more. From the viewpoint of distance and ease of swing for a power hitter, the unit weight U1 can be set to 1.30 (g / cm) or less, further 1.29 (g / cm) or less, and further 1.28 (g / cm) or less. In the case of a shaft having a coating, the weight of the coating is included in the shaft weight.

[0076] A shaft with this unit weight U1 has a large overall shaft weight W1. It was found that if the shaft length Ls of this heavy shaft is set within the above range, the feeling is likely to deteriorate. Specifically, it was found that even when a power hitter with a fast head speed swings, the shaft feels like a stick without any sense of flex, and the head does not move smoothly.

[0077] In the shafts 6 and 16, the bending stiffness E2 is greater than the bending stiffness E1. Also, the bending stiffness E1 is 5.0 (kgf m 2 ) or more 6.1 (kgf m 2 ) or less. In addition, the bending stiffness E2 is 6.0 (kgf m 2 ) or more 7.5 (kgf m 2 ) or less. This bending stiffness makes it easier to feel the flex of the shaft, improving the feeling. In addition, the return to normal caused by the flex improves head speed and increases distance. The first point P1 is close to the gripping area where the club is held with the left and right hands, and is slightly toward the tip of the gripping area. The second point P2 is near the axial center of the gripping area. The bending stiffness at a position close to the hands is likely to affect the feeling.

[0078] From the viewpoint of directional stability when a power hitter hits with a medium-length heavy shaft, the bending stiffness E1 is set to 5.0 (kgf m 2 ) or more is preferable, and 5.1 (kgf m 2 ) or more is preferable, and 5.2 (kgf m 2 ) or more is more preferable. For power hitters, if the flex is too great and the rebound is insufficient, the head speed will not increase. Also, if the flex is too great and the rebound is insufficient, the feeling will not improve even if there is flex. From these points of view, the bending stiffness E1 should be 5.0 (kgf m 2 ) or more is preferable, and 5.1 (kgf m 2 ) or more is preferable, and 5.2 (kgf m 2) or more is more preferable. From the viewpoint of the feeling and distance when a power hitter hits with a heavy shaft of medium length, the bending stiffness E1 should be 6.1 (kgf m 2 ) or less is preferable, and 6.0 (kgf m 2 ) or less is preferable, and 5.9 (kgf m 2 ) or less is more preferable.

[0079] From the viewpoint of directional stability when a power hitter hits with a medium-length heavy shaft, the bending stiffness E2 is set to 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 more preferable. For power hitters, if the flex is too great and the rebound is insufficient, the head speed will not increase. Also, if the flex is too great and the rebound is insufficient, the feeling will not improve even if there is flex. From these points of view, the bending stiffness E2 should be 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 more preferable. From the viewpoint of the feeling and distance when a power hitter hits with a heavy shaft of medium length, the bending stiffness E2 should be 7.5 (kgf m 2 ) or less is preferable, and 7.3 (kgf m 2 ) or less is preferable, and 7.1 (kgf m 2 ) or less is more preferable.

[0080] The shaft 6 has a forward flex and a reverse flex. Figure 8(a) is a schematic diagram showing a method for measuring the forward flex. Figure 8(b) is a schematic diagram showing a method for measuring the reverse flex.

[0081] As shown in FIG. 8(a), in the measurement of forward flex, a first support point J1 is set at a position that is a distance X1 (mm) from the tip end Tp. Furthermore, a second support point J2 is set at a position that is a distance X2 (mm) from the tip end Tp. A support Q1 that supports the shaft 6 from above is provided at the first support point J1. A support Q2 that supports the shaft 6 from below is provided at the second support point J2. In a state where no load is applied, the axis of the shaft 6 is horizontal. A load of 2.7 kgf is applied vertically downward to a load point m1 that is a distance X3 (mm) from the tip end Tp. The distance (mm) of the load point m1 between the state where no load is applied and the stable state where a load is applied is the forward flex. This distance is measured along the vertical direction.

[0082] Forward flex is measured in the position appropriate for the shaft length. If the shaft length is 40 inches (1016 mm) or more, X1 is 965 mm, X2 is 825 mm, and X3 is 64 mm. If the shaft length is 39.5 inches (1003 mm) or more but less than 40 inches (1016 mm), X1 is 952 mm, X2 is 812 mm, and X3 is 64 mm. If the shaft length is 39 inches (991 mm) or more but less than 39.5 inches (1003 mm), X1 is 939 mm, X2 is 799 mm, and X3 is 64 mm. If the shaft length is 38.5 inches (978 mm) or more but less than 39 inches (991 mm), X1 is 927 mm, X2 is 787 mm, and X3 is 64 mm. If the shaft length is 38 inches (965 mm) or greater but less than 38.5 inches (978 mm), X1 is 914 mm, X2 is 774 mm, and X3 is 64 mm. If the shaft length is 37.5 inches (953 mm) or greater but less than 38 inches (965 mm), X1 is 901 mm, X2 is 761 mm, and X3 is 64 mm. If the shaft length is less than 37.5 inches (953 mm), X1 is 889 mm, X2 is 749 mm, and X3 is 64 mm.

[0083] The cross-sectional shape of the part of the support Q1 that abuts against the shaft (hereinafter referred to as the abutment part) is as follows: In a cross section parallel to the shaft axial direction, the cross-sectional shape of the abutment part of the support Q1 has a convex round shape. The radius of curvature of this round shape is 15 mm. In a cross section perpendicular to the shaft axial direction, the cross-sectional shape of the abutment part of the support Q1 has a concave round shape. The radius of curvature of this concave round shape is 40 mm. In a cross section perpendicular to the shaft axial direction, the horizontal length (depth direction length in FIG. 8(a)) of the abutment part of the support Q1 is 15 mm. The shape of the abutment part of the support Q2 is the same as that of the support Q1. The cross-sectional shape of the abutment part of the load indenter (not shown) that applies a load of 2.7 kgf at the load point m1 has a convex round shape in a cross section parallel to the shaft axial direction. The radius of curvature of this round shape is 10 mm. The cross-sectional shape of the contact portion of the load indenter (not shown) that applies a load of 2.7 kgf at the load point m1 is a straight line in a cross section perpendicular to the shaft axial direction. The length of this straight line is 18 mm. A weight including this load indenter is hung from the load point m1.

[0084] As shown in Fig. 8(b), in the measurement of the reverse flex, the first support point J1 is located at a position Y1 (mm) away from the tip end Tp, the second support point J2 is located at a position Y2 (mm) away from the tip end Tp, the load point m2 is located at a position Y3 (mm) away from the tip end Tp, and the load is 1.3 kgf. The reverse flex is measured in the same manner as the forward flex.

[0085] Inverse flex is also measured in the position appropriate for the shaft length. If the shaft length is 40 inches (1016 mm) or more, Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 824 mm. If the shaft length is 39.5 inches (1003 mm) or more but less than 40 inches (1016 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 811 mm. If the shaft length is 39 inches (991 mm) or more but less than 39.5 inches (1003 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 798 mm. If the shaft length is 38.5 inches (978 mm) or more but less than 39 inches (991 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 786 mm. If the shaft length is 38 inches (965 mm) or more but less than 38.5 inches (978 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 773 mm. If the shaft length is 37.5 inches (953 mm) or more but less than 38 inches (965 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 760 mm. If the shaft length is less than 37.5 inches (953 mm), Y1 is set to 12 mm, Y2 is set to 152 mm, and Y3 is set to 748 mm.

[0086] From the viewpoint of feeling and distance when a power hitter hits with a heavy shaft of intermediate length, the forward flex is preferably 78 mm or more, more preferably 81 mm or more, and more preferably 83 mm or more. From the viewpoint of directional stability when a power hitter hits with a heavy shaft of intermediate length, the forward flex is preferably 92 mm or less, more preferably 90 mm or less, and more preferably 87 mm or less.

[0087] From the viewpoint of distance when a power hitter hits with a heavy shaft of medium length, the reverse flex is preferably 41 mm or more, more preferably 43 mm or more, and more preferably 45 mm or more. From the viewpoint of directional stability when a power hitter hits with a heavy shaft of medium length, the reverse flex is preferably 53 mm or less, more preferably 51 mm or less, and more preferably 49 mm or less.

[0088] The shaft 6 has a shaft torque. The shaft torque is the torsional angle when a certain torque is applied to the shaft. The larger the shaft torque, the lower the torsional rigidity and the more easily twisting occurs.

[0089] Figure 9 is a schematic diagram showing a method for measuring shaft torque. The section from 40 mm from the tip end Tp to the tip end Tp is fixed by jig M1. This fixation is achieved by an air chuck. Jig M2 is fixed to a section 50 mm wide from a position 825 mm away from jig M1 towards the butt end Bt. This fixation is achieved by an air chuck. With jig M1 fixed, jig M2 is rotated to apply a torque Tr of 13.9 kg cm to shaft 6. The twisting angle caused by this torque Tr is the shaft torque.

[0090] If the shaft torque is too small, a stiff feeling may occur at the time of impact. From this viewpoint, the shaft torque is preferably 1.4° or more, more preferably 1.6° or more, and more preferably 1.8° or more. From the viewpoint of directional stability when a power hitter hits with a heavy shaft of an intermediate length, the shaft torque is preferably 2.8° or less, more preferably 2.6° or less, and more preferably 2.4° or less.

[0091] In this application, the following weights are defined:

[0092] The total weight of the shaft 6 is defined as W1. The weight W1 is the total weight of the shaft 6. If the shaft 6 is painted, the weight of the paint is also included in W1.

[0093] The weight of the straight layer in the entire shaft 6 is defined as S1. The weight S1 may be calculated based on the weight of the prepreg sheet. The total weight of all the straight sheets used in the shaft 6 may be defined as the weight S1.

[0094] The weight of the bias layer in the entire shaft 6 is defined as B1. The weight B1 may be calculated based on the weight of the prepreg sheet. The total weight of all the bias sheets used in the shaft 6 may be defined as weight B1.

[0095] The weight of the hoop layer in the entire shaft 6 is defined as H1. The weight H1 may be calculated based on the weight of the prepreg sheet. The total weight of all the hoop sheets used in the shaft 6 may be defined as the weight H1.

[0096] The weight of the shaft 6 in the specific butt region Tb is defined as W2. The weight W2 may be calculated based on the weight of the prepreg sheet. The total weight of all sheets present in the specific butt region Tb may be defined as weight W2. The shaft 6 may be cut at the first point P1 and the second point P2 to create a shaft piece in the specific butt region Tb. The weight of this shaft piece may be defined as weight W2.

[0097] The weight of the straight layer in the specific batt region Tb is defined as S2. The weight S2 may be calculated based on the weight of the prepreg sheet. The total weight of all the straight sheets present in the specific batt region Tb may be defined as the weight S2.

[0098] The weight of the bias layer in the specific butt region Tb is defined as B2. The weight B2 may be calculated based on the weight of the prepreg sheet. The total weight of all the bias sheets present in the specific butt region Tb may be defined as weight B2.

[0099] The weight of the hoop layer in the specific batt region Tb is defined as H2. The weight H2 may be calculated based on the weight of the prepreg sheet. The total weight of all the hoop sheets present in the specific batt region Tb may be defined as the weight H2.

[0100] The ratio of the weight S1 of the straight layer to the total weight W1 of the shaft 6 is also called the total SP content. It has been found that it is preferable to lower the total SP content for a heavy shaft of intermediate length, even when a power hitter is hitting. A low total SP content provides a sense of flex, improving the feeling of the power hitter. From the viewpoint of the feeling and distance when a power hitter hits with a heavy shaft of intermediate length, the total SP content is preferably 16% or less, more preferably 15.5% or less, and more preferably 15% or less. The phenomenon in which the flex during the downswing returns at the time of impact is called flex return. The flex return increases the head speed. If the flex return is insufficient, the head speed decreases. From the viewpoint of the flex return when a power hitter hits with a heavy shaft of intermediate length, the total SP content is preferably 11% or more, more preferably 12% or more, and more preferably 13% or more.

[0101] The ratio of the weight B1 of the bias layer to the total weight W1 of the shaft 6 is also referred to as the total BP content. By increasing the total BP content and decreasing the total SP content, the bending stiffness E1 and bending stiffness E2 can be suppressed while increasing the unit weight U1, and a feeling of flexibility can be obtained. The twisting of the shaft 6 caused by the strong impact of a power hitter can reduce the directional stability and the feeling at the time of impact. However, by increasing the total BP content, the directional stability is increased and the feeling is also good even when the power hitter hits. From the viewpoint of the directional stability and the feeling at the time of impact when the power hitter hits with a heavy shaft of an intermediate length, the total BP content is preferably 70% or more, more preferably 72% or more, and more preferably 74% or more. If the torsional stiffness is excessively large, the twisting is excessively suppressed, and the impact may feel hard. From this viewpoint, the total BP content is preferably 84% or less, more preferably 82% or less, and more preferably 80% or less.

[0102] The ratio of the weight H1 of the hoop layer to the total weight W1 of the shaft 6 is also referred to as the total HP content. When the straight layer is reduced, a feeling of flexibility is generated, while for a power hitter, the sense of stability at the hand (a position close to the gripping area) is likely to decrease, and the sense of firmness is likely to decrease. The hoop layer can create a sense of firmness while suppressing the bending stiffness E1 and bending stiffness E2 to maintain the feeling of flexibility. This sense of stability and firmness enhances the feeling for a power hitter. From the viewpoint of the sense of stability and firmness during a swing, the total HP content is preferably 7% or more, more preferably 8% or more, and more preferably 9% or more. From the viewpoint of ensuring the total BP content, the total HP content is preferably 14% or less, more preferably 13% or less, and more preferably 12% or less. The total HP content may be 0%. That is, the shaft 6 does not need to have a hoop layer.

[0103] The ratio of the weight S2 of the straight layer to the shaft weight W2 in the specific butt region Tb is also called the butt SP content. The butt SP content is preferably smaller than the overall SP content. The shaft behavior in the vicinity of the gripping region is easily transmitted to the hand. By lowering the SP content in the vicinity of the gripping region, it becomes easier to obtain a sense of flexibility while maintaining a firm feel, improving the feeling for power hitters.

[0104] From the viewpoint of the feeling when a power hitter hits with a heavy shaft of medium length, the bat SP content is preferably 15% or less, more preferably 14% or less, and more preferably 13% or less. From the viewpoint of the rebound when a power hitter hits with a heavy shaft of medium length, the bat SP content is preferably 8% or more, more preferably 9% or more, and more preferably 10% or more.

[0105] The ratio of the weight H2 of the hoop layer to the weight W2 of the shaft in the specific butt region Tb is also called the butt HP content. The butt HP content is preferably greater than the overall HP content. By increasing the HP content near the hand, the sense of stability and firmness can be further improved.

[0106] From the viewpoint of ensuring the bat BP content, the bat HP content is preferably 15% or less, more preferably 14% or less, and more preferably 13% or less. From the viewpoint of stability and firmness in the hand, the bat HP content is preferably 8% or more, more preferably 9% or more, and more preferably 10% or more.

[0107] The ratio of the weight B2 of the bias layer to the shaft weight W2 in the specific butt region Tb is also referred to as the bat BP content. A high bat BP content increases directional stability when a power hitter hits. By increasing the BP content in the specific butt region Tb close to the hand, the feeling at impact is further improved and directional stability can also be increased. From these viewpoints, the bat BP content is preferably 70% or more, more preferably 72% or more, and more preferably 74% or more. If the torsional rigidity is excessively high, the impact may feel hard. From this viewpoint, the bat BP content is preferably 84% or less, more preferably 82% or less, and more preferably 80% or less.

[0108] The weight per unit length of the shaft 6 in the specific butt region Tb is also referred to as unit weight U2. The unit weight U2 is preferably 1.30 (g / cm) or more, more preferably 1.31 (g / cm) or more, and more preferably 1.32 (g / cm) or more. By increasing the unit weight U2, the movement of the grip region can be stabilized. If the unit weight U2 is too large, the feeling of flexibility can be reduced. From this viewpoint, the unit weight U2 is preferably 1.40 (g / cm) or less, more preferably 1.39 (g / cm) or less, and more preferably 1.38 (g / cm) or less.

[0109] From the viewpoint of stability at hand, it is preferable that the unit weight U2 is larger than the above-mentioned unit weight U1.

[0110] In general, a light shaft is suitable for a golfer with little power. A soft shaft is also suitable for a golfer with little power. On the other hand, if a shaft is too light, a powerful golfer will not be able to time the impact properly. A relatively stiff shaft is also suitable for a powerful golfer. From this perspective, the softer the shaft, the lighter it tends to be, and the stiffer the shaft, the heavier it tends to be.

[0111] The shaft of the embodiment is for a power hitter and is very heavy. However, this shaft is flexible for its weight. In other words, this shaft has small bending stiffness E1 and E2 for its weight.

[0112] It has been found that by reducing the bending stiffness E1 and bending stiffness E2 relative to the shaft weight, the feeling when a power hitter hits with a shaft of an intermediate length is improved. From this viewpoint, E1 / U1 is preferably 5.5 or less, more preferably 5.3 or less, more preferably 5.2 or less, and more preferably 5.1 or less. From the viewpoint of avoiding an excessively large unit weight U1 and an excessively small bending stiffness E1, E1 / U1 is preferably 3.8 or more, more preferably 3.9 or more, and more preferably 4.0 or more. From the same viewpoint, E2 / U1 is preferably 7.0 or less, more preferably 6.6 or less, more preferably 6.3 or less, more preferably 6.2 or less, and more preferably 6.1 or less. From the viewpoint of avoiding an excessively large unit weight U1 and an excessively small bending stiffness E2, E2 / U1 is preferably 4.6 or more, more preferably 4.8 or more, more preferably 4.9 or more, and more preferably 5.0 or more.

[0113] A golf club having a shaft 6 has a club length. Due to the presence of a head 4 and a grip 8, the club length differs slightly from the shaft length Ls (see FIG. 1). The club length is preferably 38 inches (965 mm) or more and preferably 41 inches (1041 mm) or less. This preferred club length corresponds to the preferred shaft length Ls (951 mm or more and 1017 mm or less).

[0114] The club length may be 38 inches (965 mm) or more, further 38.5 inches (978 mm) or more, and further 38.75 inches (984 mm) or more. The club length may be 41 inches (1041 mm) or less, further 40.5 inches (1029 mm) or less, and further 40.25 inches (1022 mm) or less. This club length is highly suitable for hybrid clubs. This club length may be applied to wood clubs or iron clubs.

[0115] Club length is measured in accordance with the regulations of the Royal and Ancient Golf Club of Saint Andrews (R&A). These regulations are described in "1c Length" under "1 Club" in "Appendix II Club Design" in the latest Rules of Golf published by the R&A. This measurement method is also called the 60-degree measurement method because the club is placed on a horizontal plane and the sole is placed on a surface that is at an angle of 60 degrees to the horizontal plane.

[0116] Preferably, the shaft is used in a hybrid club. The head of the hybrid club is a hybrid head. Hybrid heads are classified into wood-type hybrid heads and iron-type hybrid heads. Wood-type hybrid heads have a curved hitting face and a crown. Iron-type hybrid heads have a flat hitting face and no crown. Iron-type hybrid heads usually have a hollow structure.

[0117] The wood-type hybrid head may have the following configurations (1a) to (1e). (1a) Curved hitting face (1b) Hollow structure (1c)90cm 3 More than 140cm 3 The volume of (1d) Real loft angle between 15 degrees and 33 degrees (1e) Presence of crown

[0118] The iron-type hybrid head may have the following configurations (2a) to (2d). (2a) Flat hitting face (2b) Hollow or cavity-back structure (2c) Real loft angle between 15 degrees and 25 degrees (2d) Absence of Crown

[0119] In Japan in particular, a hybrid head is sometimes called a utility head, and an iron-type hybrid head in particular is sometimes called a utility head.

[0120] The following Tables 1 and 2 show examples of prepregs that can be used in the shaft of the present invention. These prepregs are commercially available. By using these prepregs, the specifications of the shaft can be adjusted.

[0121] [Table 1]

[0122] [Table 2] EXAMPLES

[0123] [Example 1] A shaft was produced according to the shaft manufacturing process described above. The sheet configuration of the shaft was as shown in FIG. 5. All straight sheets had a fiber tensile modulus of 24 (t / mm 2 ) prepreg. All bias sheets had a fiber tensile modulus of 24 (t / mm 2 All the hoop sheets were prepregs with a fiber tensile modulus of 24 (t / mm 2 ) prepreg. The shaft length Ls was 993 mm. A hybrid head (iron type) and grip were attached to the obtained shaft to obtain a golf club (2 iron) with a club length of 39.5 inches (1003 mm).

[0124] [Example 2] A shaft and a golf club according to Example 2 were obtained in the same manner as Example 1, except that the sheet configuration was changed as shown in FIG. 6 and the specifications were set as shown in Table 3.

[0125] [Examples 3 to 6] The sheet configuration and prepreg types were adjusted to the specifications shown in Table 3, but other than that, the same procedures as in Example 1 or 2 were followed to obtain shafts and golf clubs according to Examples 3 to 6.

[0126] [Comparative Examples 1 to 4] The sheet configuration and prepreg type were adjusted to the specifications shown in Table 4, and other conditions were the same as in Example 1 or 2, to obtain shafts and golf clubs according to Comparative Examples 1 to 4.

[0127] The specifications and evaluation results of Examples 1 to 6 are shown in the following Table 3. The specifications and evaluation results of Comparative Examples 1 to 4 are shown in the following Table 4.

[0128] [Table 3]

[0129] [Table 4]

[0130] <Evaluation of head speed> The test was conducted by a male professional golfer with a driver head speed of 50 m / s or more who actually hit the balls. The golf balls used were "SRIXON Z-STAR XV" manufactured by Sumitomo Rubber Industries. Five balls were hit with each club, and the head speed was measured for each hit. The average value of the five balls is shown in the "Head Speed" column in Tables 3 and 4.

[0131] <Evaluation of directional stability> In the above hits where the head speed was measured, the directional stability of the hit ball was also measured. In all hits, the distance (yards) between the line connecting the position of the hit ball and the target and the final destination of the hit ball was measured. This distance was considered to be a positive value whether the ball deviated to the right or left. The average value of this value is shown in the "directional stability" column in Tables 3 and 4.

[0132] <Feeling evaluation> The feeling was also measured during the above shot in which the head speed was measured. The professional golfers rated the feeling during the shot on a scale of 1 to 5. The higher the evaluation score, the better the feeling. The evaluation scores are shown in the "Feeling" column of Tables 3 and 4.

[0133] As shown in Tables 3 and 4, the Examples were rated higher than the Comparative Examples.

[0134] The following notes are part of the invention disclosed in this application. [Appendix 1] A golf club shaft formed of a plurality of fiber reinforced resin layers, A tip end and The end of the bat, A bending stiffness E1 at a first point 290 mm away from the butt end; A bending stiffness E2 at a second point 120 mm away from the butt end; It has The bending stiffness E2 is greater than the bending stiffness E1, The bending stiffness E1 is 5.0 (kgf m 2 ) or more 6.1 (kgf m 2 ) or less, The bending stiffness E2 is 6.0 (kgf m 2 ) or more 7.5 (kgf m 2 ) or less, The unit weight U1 per unit length of the entire shaft is 1.15 (g / cm) or more and 1.30 (g / cm) or less, A golf club shaft with a shaft length of 951mm or more and 1017mm or less. [Appendix 2] The plurality of fiber reinforced resin layers include a straight layer, a bias layer, and a hoop layer, The total weight of the shaft is W1, The weight of the straight layer in the entire shaft is S1, The weight of the bias layer in the entire shaft is B1, When the weight of the hoop layer in the entire shaft is H1, The total SP content, which is the ratio of the weight S1 to the weight W1, is 16% or less; The total BP content, which is the ratio of the weight B1 to the weight W1, is 70% or more; 2. The golf club shaft according to claim 1, wherein an overall HP content, which is a ratio of the weight H1 to the weight W1, is 14% or less. [Appendix 3] 3. The golf club shaft according to claim 2, wherein the total HP content is 7% or more. [Appendix 4] The area from the first point to the second point is a specific bat area, The weight of the shaft in the specific butt region is W2, The weight of the straight layer in the specific butt region is S2, The weight of the bias layer in the specific butt region is B2, When the weight of the hoop layer in the specific batt region is H2, The batt SP content, which is the ratio of the weight S2 to the weight W2, is smaller than the total SP content, 4. The golf club shaft according to claim 1, wherein a butt HP content, which is a ratio of the weight H2 to the weight W2, is greater than the total HP content. [Appendix 5] The area from the first point to the second point is a specific bat area, The weight of the shaft in the specific butt region is W2, The weight of the straight layer in the specific butt region is S2, The weight of the bias layer in the specific butt region is B2, When the weight of the hoop layer in the specific batt region is H2, The batt SP content, which is the ratio of the weight S2 to the weight W2, is 15% or less, The batt BP content, which is the ratio of the weight B2 to the weight W2, is 70% or more; The golf club shaft according to any one of appendices 1 to 4, wherein a butt HP content, which is a ratio of the weight H2 to the weight W2, is 15% or less. [Appendix 6] 6. The golf club shaft according to claim 4, wherein the butt HP content is 8% or more. [Appendix 7] When the area from the first point to the second point is defined as a specific bat area, 7. The golf club shaft according to claim 1, wherein the unit weight U2 per unit length in the specific butt region is 1.30 (g / cm) or more, and the unit weight U2 is greater than the unit weight U1. [Appendix 8] 8. The golf club shaft according to any one of claims 1 to 7, wherein E1 / U1 is 5.5 or less and E2 / U1 is 7.0 or less. [Appendix 9] A golf club shaft according to any one of claims 1 to 8, a head, and a grip, A golf club with a club length between 38 inches and 41 inches. [Appendix 10] 10. The golf club according to claim 9, which is a hybrid club. [Explanation of symbols]

[0135] 2. Golf clubs 4. Golf club head 4a: Striking face 4b Crown 4c···Sole 6. Golf club shaft 8. Grip 10. Golf clubs 12. Golf club head 12a... Striking face 12b···Top blade 12c···Sole 16. Golf club shaft s1~s12: Prepreg sheets (layers) Ls: Shaft length Bt: Butt end Tp: Chip end P1: Point 1 P2...Second point Tb...specific bat region

Claims

1. A golf club shaft formed of a plurality of fiber reinforced resin layers, A tip end and The end of the bat, A bending stiffness E1 at a first point 290 mm away from the butt end; A bending stiffness E2 at a second point 120 mm away from the butt end; It has The bending stiffness E2 is greater than the bending stiffness E1, The bending rigidity E1 is 5.0 (kgf m ２ ) or more 6.1 (kgf・m ２ ) or less, The bending rigidity E2 is 6.0 (kgf m ２ ) or more 7.5 (kgf・m ２ ) or less, A unit weight U1 per unit length of the entire shaft is 1.15 (g / cm) or more and 1.30 (g / cm) or less, A golf club shaft having a shaft length of 951 mm or more and 1017 mm or less.

2. The plurality of fiber reinforced resin layers include a straight layer, a bias layer, and a hoop layer, The total weight of the shaft is W1, The weight of the straight layer in the entire shaft is S1, The weight of the bias layer in the entire shaft is B1, When the weight of the hoop layer in the entire shaft is H1, The total SP content, which is the ratio of the weight S1 to the weight W1, is 16% or less; The total BP content, which is the ratio of the weight B1 to the weight W1, is 70% or more; 2. The golf club shaft according to claim 1, wherein a total HP content, which is a ratio of said weight H1 to said weight W1, is 14% or less.

3. 3. The golf club shaft of claim 2, wherein the total HP content is 7% or more.

4. The area from the first point to the second point is set as a specific bat area, The weight of the shaft in the specific butt region is W2, The weight of the straight layer in the specific butt region is S2, The weight of the bias layer in the specific butt region is B2, When the weight of the hoop layer in the specific batt region is H2, The butt SP content, which is the ratio of the weight S2 to the weight W2, is smaller than the total SP content, 4. The golf club shaft according to claim 1, wherein a butt HP content, which is a ratio of the weight H2 to the weight W2, is greater than the total HP content.

5. The area from the first point to the second point is set as a specific bat area, The weight of the shaft in the specific butt region is W2, The weight of the straight layer in the specific butt region is S2, The weight of the bias layer in the specific butt region is B2, When the weight of the hoop layer in the specific batt region is H2, The batt SP content, which is the ratio of the weight S2 to the weight W2, is 15% or less, The bat BP content, which is the ratio of the weight B2 to the weight W2, is 70% or more, 4. The golf club shaft according to claim 1, wherein a butt HP content, which is a ratio of the weight H2 to the weight W2, is 15% or less.

6. 6. The golf club shaft according to claim 5, wherein the butt HP content is 8% or more.

7. When the area from the first point to the second point is determined as a specific bat area, 4. The golf club shaft according to claim 1, wherein a unit weight U2 per unit length in the specific butt region is 1.30 (g / cm) or more, and the unit weight U2 is greater than the unit weight U1.

8. 4. The golf club shaft according to claim 1, wherein E1 / U1 is equal to or less than 5.5 and E2 / U1 is equal to or less than 7.

0.

9. A golf club shaft according to any one of claims 1 to 3, a head, and a grip, A golf club having a club length of 38 inches or more and 41 inches or less.

10. 10. The golf club of claim 9 which is a hybrid club.

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