Shaft and method for manufacturing the same, shaft for golf club

Abstract

To provide a shaft that is lighter in weight while maintaining high thread strength, a method for manufacturing the same, and a golf club shaft made from the shaft. [Solution] A shaft (10) having a plurality of layers A(11) and at least one layer B(12), wherein each layer A(11) comprises a cured product of a thermosetting resin, and each layer B(12) comprises a thermoplastic resin and a continuous fiber substrate, and at least one layer B(12) is positioned between two layers A(11).

Description

[Technical Field]

[0001] This invention relates to a shaft, a method for manufacturing the same, and a shaft for a golf club made from the shaft. This application claims priority based on Japanese Patent Application No. 2021-062182, filed in Japan on March 31, 2021, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] Conventionally, shafts are known that consist only of a fiber-reinforced resin layer containing thermosetting resin and fibers. Such shafts are used in golf clubs and the like (see, for example, Patent Document 1). The shaft is manufactured using the sheet wrap molding method. In the sheet wrap molding method, prepreg is wound around a core metal called a mandrel. The wound prepreg is then heat-cured to obtain the shaft (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2009-189554 [Patent Document 2] Japanese Patent Publication No. 2000-127254 [Overview of the project] [Problems that the invention aims to solve]

[0004] Prepregs containing thermoplastic resin as the matrix resin (thermoplastic resin prepregs) have higher bending rigidity, lower tack, and inferior drape compared to prepregs containing thermosetting resin as the matrix resin (thermosetting resin prepregs). Therefore, it is difficult to mold thermoplastic resin prepregs to conform to the shape of a mandrel, and if they are wrapped around a mandrel using the sheet-wrap method without sufficient conformation, delamination between layers may occur before and after molding. In order to use shafts with high threading strength in practical applications, it was necessary to increase the number of layers of fiber-reinforced resin containing thermosetting resin and fibers. However, there was a concern that increasing the number of fiber-reinforced resin layers would increase the overall weight of the shaft.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a method for manufacturing a shaft in which thermoplastic resin prepreg has been wound, which has not been possible to wind into a shaft shape in the past. Furthermore, the present invention aims to provide a shaft that is lighter in weight while maintaining high thread strength, a method for manufacturing the same, and a golf club shaft made from the shaft. [Means for solving the problem]

[0006] The configuration of the present invention that achieves the above objective is as follows. [1] A shaft having multiple layers A and at least one layer B, The aforementioned layer A comprises a cured product of a thermosetting resin, and the aforementioned layer B comprises a thermoplastic resin and a continuous fiber substrate. A shaft in which at least one of the layers B is positioned between two of the layers A. [2] The shaft according to [1], wherein the continuous fiber base material is a woven fabric base material or a unidirectional fiber base material. [3] The shaft according to [1] or [2], wherein layer A is a fiber-reinforced resin layer containing a continuous fiber base material. [4] The shaft according to [3], wherein the continuous fiber base material included in layer A is a woven fabric base material or a unidirectional fiber base material. [5] The shaft according to any one of [1] to [4], wherein the thermoplastic resin comprises polyetherimide. [6] The shaft according to any one of [1] to [5], wherein the thermosetting resin comprises an epoxy resin. [7] The shaft according to any one of [1] to [6], wherein the continuous fiber base material contained in layer B contains carbon fibers. [8] The shaft according to any one of [1] to [7], wherein the content of the thermoplastic resin is 1% by mass or more and 80% by mass or less with respect to the total mass of the thermosetting resin and the thermoplastic resin. [9] The shaft according to any one of [1] to [8], wherein the ratio of the thickness of layer B to the sum of the thickness of layer A and the thickness of layer B (thickness of layer B / sum of the thickness of layer A and the thickness of layer B) is 0.5% or more and 90% or less.

[10] The shaft according to any one of [1] to [9], wherein the shaft is hollow.

[11] The shaft according to any one of [1] to

[10] , wherein layer A is arranged as the outermost layer.

[12] The shaft according to

[11] , arranged in the order of layer A - layer B - layer A. A golf club shaft consisting of one of the shafts described in

[13] [1] to

[12] .

[14] A method for manufacturing a shaft, comprising a plurality of layers A and at least one layer B, wherein layer A includes a cured product of a thermosetting resin and layer B includes a thermoplastic resin and a continuous fiber substrate, A step of forming a laminate of prepregs by winding a thermosetting resin sheet a, which will be layer A, and a prepreg b, which will be layer B, around the outer circumference of a mandrel, following the shape of the mandrel, in the order of prepreg b, then thermosetting resin sheet a, starting from the mandrel side. The process of heating the laminate, A method for manufacturing a shaft, comprising the step of separating the heated laminate from the mandrel.

[15] The method for manufacturing a shaft according to

[14] , wherein the layer B is arranged between two of the layers A.

[16] The method for manufacturing a shaft according to

[14] or

[15] , wherein the shaft is hollow.

[17] The method for manufacturing a shaft according to

[16] , wherein the layer B is arranged on the hollow side of at least one of the layers A.

[18] A step of forming a laminate of prepregs by winding a thermosetting resin sheet a containing thermosetting resin and fibers and a prepreg b containing thermoplastic resin and fibers around the outer circumference of a mandrel, following the shape of the mandrel, in the order of prepreg b, thermosetting resin sheet a, starting from the mandrel side, A method for manufacturing a shaft, comprising the step of heating the laminated body.

[19] A method for manufacturing a shaft, comprising the step of winding a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers around the outer circumference of a mandrel, following the shape of the mandrel, so that the thermosetting resin sheet a and the prepreg b are in that order from the mandrel side, thereby forming a laminate including the portion where the thermosetting resin sheet a and the prepreg b are in contact.

[20] A method for manufacturing a shaft according to

[19] , comprising the step of heating the laminate.

[21] A method for manufacturing a shaft, comprising the steps of winding a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers around the outer circumference of a mandrel, following the shape of the mandrel, in the order of the thermosetting resin sheet a and the prepreg b from the mandrel side, and winding the prepreg b on top of the thermosetting resin sheet a so that it is in direct contact with the thermosetting resin sheet a, thereby forming a laminate of the thermosetting resin sheet a and the prepreg b.

[22] A method for manufacturing a shaft, comprising the step of forming a wound body by winding a laminated sheet, which is made by laminating a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers, around the outer circumference of a mandrel along the shape of the mandrel.

[23] The method for manufacturing a shaft according to

[22] , wherein when winding the laminated sheet, the thermosetting resin sheet a is positioned on the inside of the shaft.

[24] A method for manufacturing a shaft according to

[22] or

[23] , comprising the step of heating the wound body.

[25] A method for manufacturing a shaft according to any one of

[22] to

[24] , further comprising the step of winding a thermosetting resin sheet a2, which is different from the thermosetting resin sheet a, around the shaft on which the laminated sheet is wound.

[26] The method for manufacturing a shaft according to any one of

[22] to

[25] , wherein the laminated sheet is wound in the order of the thermosetting resin sheet a - the prepreg b from the mandrel side.

[27] The method for manufacturing a shaft according to

[22] , wherein the laminated sheet further includes the thermosetting resin sheet a, and the laminated sheet is wound in the order of the thermosetting resin sheet a - the prepreg b - the thermosetting resin sheet a from the mandrel side.

[28] The method for manufacturing a shaft according to any one of

[22] to

[27] , wherein the position of the edge of the thermosetting resin sheet a that serves as the start end of winding around the outer periphery of the mandrel is different from the position of the edge of the prepreg b that serves as the start end of winding around the outer periphery of the mandrel.

[29] The method for manufacturing a shaft according to any one of

[25] to

[28] , wherein the position of the edge of the thermosetting resin sheet a2 that serves as the start end of winding around the outer periphery of the mandrel is different from the position of the edge of the prepreg b that serves as the start end of winding around the outer periphery of the mandrel.

[30] The method for manufacturing a shaft according to any one of

[22] to

[29] , wherein the area of contact between the thermosetting resin sheet a and the prepreg b is 10% or more with respect to the area of the prepreg b.

[31] The method for manufacturing a shaft according to any one of

[22] to

[30] , wherein the thermosetting resin sheet a contains fibers.

[32] The method for manufacturing a shaft according to any one of

[22] to

[31] , wherein the fiber volume fraction of the fibers contained in the prepreg b is 30% by volume or more.

[33] The method for manufacturing a shaft according to any one of

[22] to

[32] , wherein the ratio of the thickness of one sheet of the prepreg b to the thickness of one sheet of the thermosetting resin sheet a (thickness of the prepreg b / thickness of the thermosetting resin sheet a) is 1.5 or less.

[34] The method for manufacturing a shaft according to any one of

[22] to

[33] , wherein the length of the fibers contained in the prepreg b is 1% or more of the length of the shaft.

[35] The ratio of the length in the width direction of the thermosetting resin sheet a to the radius of the shaft (length in the width direction of the thermosetting resin sheet a / radius of the shaft) is 0.5 or more, and the method for manufacturing a shaft according to any one of

[22] to

[34] .

[36] The thermosetting resin contained in the thermosetting resin sheet a is an epoxy resin, and the method for manufacturing a shaft according to any one of

[22] to

[35] .

[37] The thermoplastic resin contained in the prepreg b is a polyetherimide, and the method for manufacturing a shaft according to any one of

[22] to

[36] .

[38] The fiber contained in the thermosetting resin sheet a contains carbon fiber, and the method for manufacturing a shaft according to

[31] .

[39] The fiber contained in the prepreg b contains carbon fiber, and the method for manufacturing a shaft according to any one of

[22] to

[38] .

[40] The prepreg b is arranged so as to be present at a position within 50% from the innermost side of the laminated sheet with respect to the thickness of the laminated sheet, and the method for manufacturing a shaft according to any one of

[22] to

[39] .

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a shaft with reduced weight while maintaining high thread cutting strength, a method for manufacturing the same, and a golf club shaft composed of the shaft.

Brief Description of the Drawings

[0008] [Figure 1] It is a cross-sectional view along the longitudinal direction of a shaft according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view along a direction perpendicular to the longitudinal direction of a shaft according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view along a direction perpendicular to the longitudinal direction of a shaft according to an embodiment of the present invention. [Figure 4] It is a cross-sectional view along a direction perpendicular to the longitudinal direction of a shaft according to an embodiment of the present invention. [Figure 5]This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 6] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 7] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 8] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 9] This is a plan view of a shaft relating to one embodiment of the present invention. [Figure 10] This is a plan view of a shaft relating to one embodiment of the present invention. [Figure 11] This is a plan view of a shaft relating to one embodiment of the present invention. [Figure 12] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 13] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 14] This is a cross-sectional view of a shaft according to one embodiment of the present invention, taken along the longitudinal and perpendicular directions. [Figure 15] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 16] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 17] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 18] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 19] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 20] This is a plan view showing the position where layer B is located in a shaft according to one embodiment of the present invention. [Figure 21]This is a schematic diagram showing the positions of the edges of the prepreg and the thermosetting resin sheet. [Figure 22] This is a schematic diagram showing the positions of the edges of the prepreg and the thermosetting resin sheet. [Figure 23] This is a schematic diagram showing the ratio of the total length L over which the prepreg and thermosetting resin sheet are in contact, to the radius r from the center of the shaft to the outermost surface of the thermosetting resin sheet in contact with the prepreg. [Figure 24] This is a schematic diagram showing the shape of a mandrel used in the manufacture of a shaft according to one embodiment of the present invention. [Figure 25] This is a pattern diagram showing the shape of a prepreg used in the manufacture of a shaft according to one embodiment of the present invention. [Figure 26] This is a schematic diagram of a golf club shaft according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] This paper describes the shaft of the present invention, a method for manufacturing the same, and embodiments of a golf club shaft composed of the shaft. This embodiment is provided to give a better understanding of the spirit of the invention and does not limit the present invention unless otherwise specified.

[0010] [shaft] A shaft according to one embodiment of the present invention is a shaft having a plurality of layers A and at least one layer B, wherein each layer A includes a cured product of a thermosetting resin, and each layer B includes a thermoplastic resin and a continuous fiber substrate, and at least one layer B is disposed between two of the layers A.

[0011] The shaft of this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view of the shaft of this embodiment along its longitudinal direction. Figure 2 is a cross-sectional view of the shaft of this embodiment along a direction perpendicular to its longitudinal direction. The shaft 10 of this embodiment shown in Figure 1 has two layers A11 (11A, 11B) and one layer B12. In the shaft 10 of this embodiment, the one layer B12 is positioned between the two layers A11A and layer A11B. The shaft 10 has a hollow section 20 in the center.

[0012] The shape of the shaft 10 may be circular in cross-section along the longitudinal and perpendicular directions, as shown in Figure 3; elliptical in cross-section as shown in Figure 4; polygonal in cross-section as shown in Figure 5; or polygonal with rounded corners in cross-section as shown in Figure 6. Furthermore, the shape of 10 may not have a completely connected cross-section along the longitudinal and perpendicular directions, as shown in Figure 7; or it may not be hollow inside, as shown in Figure 8. In addition, the shaft 10 may have a varying thickness in the longitudinal direction, as shown in Figure 9; a gradual change in thickness, as shown in Figure 10; or it may be curved or bent in the longitudinal direction, as shown in Figure 11.

[0013] Thermoplastic resin prepregs have inferior drape and low surface tack compared to thermosetting resin prepregs, making them difficult to roll into a tubular shape. For these reasons, conventional sheet-wrap molding methods have not been able to provide a layer B containing thermoplastic resin and a continuous fiber base material in the shaft. In this embodiment, by adopting a structure (ABA structure) in which one layer B12 is placed between two layers A11A and layer A11B, layer A11 can sandwich and fix layer B12, allowing for tubular molding and resulting in a shaft with high strength and excellent molding accuracy. Furthermore, the adoption of the ABA structure also improves productivity. Furthermore, by adopting a structure in which layer A and layer B are in contact (AB structure), or a structure in which one layer B12 is placed between two layers A11A and layer A11B (ABA structure), layer A11 sandwiches and fixes layer B12, thus suppressing delamination between layers even when molded into a tubular shape. By adopting the AB structure, a shaft with high strength and excellent molding accuracy can be obtained. In addition, by adopting the ABA structure, the sheet-wrapping method can be applied, resulting in excellent productivity of shafts including layer B.

[0014] In the shaft 10 of this embodiment, the ratio of the thickness of layer B12 to the sum of the thicknesses of layer A11 and layer B12 (in the shaft 10 shown in Figures 1 and 2, the sum of the thicknesses of layer A11A, layer A11B, and layer B12) (thickness of layer B12 / sum of the thicknesses of layer A11 and layer B12) is preferably 0.5% or more and 90% or less, more preferably 1% or more and 70% or less, even more preferably 2% or more and 50% or less, and particularly preferably 5% or more and 20% or less. If the ratio of thicknesses is above the lower limit, the thread cutting strength is improved. If the ratio of thicknesses is below the upper limit, the formability is excellent.

[0015] In the shaft 10 of this embodiment, as shown in Figures 1 and 2, it is preferable that layer B12 is positioned closer to the hollow portion 20 than layer A11A. This further improves the thread strength of the shaft 10. It is preferable that layer B12 is positioned closer to the hollow portion 20 than at least one layer A11, but it may also be positioned closer to the hollow portion 20 than two or more layers A11. It is preferable that layer A11 is the outermost layer on the side opposite to the hollow portion.

[0016] In the shaft 10 of this embodiment, it is preferable to arrange the layers in the order of layer A11A - layer B12 - layer A11B, as shown in Figures 1 and 2. This allows layer B12 to be sandwiched and fixed between layers A11A and A11B, even if layer B12 contains a thermoplastic resin with low adhesion to layer A11 which contains a cured thermosetting resin. As a result, the thread strength of the shaft 10 can be further improved.

[0017] Layers A11 and B12 can be formed by winding thermosetting resin sheets or prepregs. By placing a thermosetting resin sheet a on the outside of prepreg b, the thermosetting resin sheet a fixes prepreg b from the outside, making it easier to wind into a shaft shape. A laminate of thermosetting resin sheet a and prepreg b may be formed by winding a laminated sheet of prepreg b and thermosetting resin sheet a, or by winding prepreg b first and then winding thermosetting resin sheet a. It is preferable that the prepreg b is firmly fixed by forming a laminated sheet by laminating the thermosetting resin sheet a inside of prepreg b and prepreg b, and the thermosetting resin sheet a placed outside of prepreg b, and then winding it. Furthermore, a laminate formed by winding thermosetting resin sheet a1, prepreg b, and thermosetting resin sheet a2 from the center side of the shaft 10 may be formed by forming a laminated sheet of thermosetting resin sheet a1 and prepreg b and then winding it, or by forming a laminated sheet of prepreg b and thermosetting resin sheet a2 and then winding it. Alternatively, a laminated sheet may be formed by laminating thermosetting resin sheet a1, prepreg b, and thermosetting resin sheet a2, and then wound up; or a laminate may be formed by winding thermosetting resin sheet a1, prepreg b, and thermosetting resin sheet a2 in sequence. The thermosetting resin sheet a may or may not contain fibers.

[0018] Furthermore, Figures 12 to 14 show other examples of the shaft 10 of this embodiment, and are cross-sectional views along the longitudinal and perpendicular directions of the shaft 10 of this embodiment. As shown in Figures 12 to 14, layer B12 may be positioned at any location on the shaft 10 as long as it is sandwiched between two layers, and as shown in Figure 14, there may be multiple layers B12 as long as they are sandwiched between two layers.

[0019] <Layer A> Layer A11 is composed of a cured product of a thermosetting resin. While the thermosetting resin is not particularly limited, epoxy resins are typically used. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidylamine type epoxy resin, isocyanate-modified epoxy resin, or alicyclic epoxy resin. These epoxy resins can be used in liquid or solid states at room temperature. These epoxy resins may be used individually or in combination of two or more types.

[0020] Layer A11 may be a fiber-reinforced resin layer containing a cured thermosetting resin and a continuous fiber substrate. The continuous fiber substrate may be replaced with a discontinuous fiber substrate. Layer A11 may be composed of a fiber-reinforced resin which is a cured prepreg containing a thermosetting resin. A prepreg is a resin-impregnated reinforced fiber sheet in which a resin composition (matrix resin composition) is impregnated into a reinforced fiber substrate, which is a sheet of fiber material containing multiple reinforcing fibers. After cutting the prepreg into a predetermined shape, it is deformed using a mold or the like and heated to cure, resulting in a molded fiber-reinforced resin. The thickness of one prepreg sheet that becomes layer A after curing is, for example, 30 μm to 250 μm. From the viewpoint of handling, 40 μm to 150 μm is preferred. When layer A contains fibers, the fiber basis weight in the prepreg that becomes layer A after curing is, for example, 10 g / m². 2 ~300g / m 2 Therefore, from a handling perspective, 30g / m 2 ~250g / m 2 Preferably, 50 g / m 2 ~220g / m 2 This is preferable.

[0021] If layer A includes a continuous fiber base material, the continuous fiber base material included in layer A11 is preferably a woven fabric base material or a unidirectional fiber base material. Carbon fibers and / or glass fibers can be used as reinforcing fibers constituting the continuous fiber base material included in layer A11. It is preferable that 40% or more of the continuous fiber base material be composed of carbon fibers in order to exhibit physical properties such as strength and rigidity. The continuous fiber base material may be composed of carbon fibers only or glass fibers only. However, fiber-reinforced resins containing only carbon fibers as reinforcing fibers are preferred because they have better physical properties such as strength and rigidity compared to fiber-reinforced resins containing only glass fibers as reinforcing fibers. From this viewpoint, the proportion of carbon fiber reinforced resin in the fiber-reinforced resin in the shaft is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, so that carbon fiber reinforced resin is the main material.

[0022] It is preferable that the resin contained in layer A11 is substantially free of thermoplastic resin. If layer A11 contains a thermoplastic resin, the amount of thermoplastic resin in layer A11 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to 100% by mass of the resin.

[0023] Layer A11 contains a thermosetting resin (including both uncured resin and cured product) as a matrix resin, and preferably the thermosetting resin is the main component. Of the resin components contained in layer A11, from the viewpoint of strength, it is preferable that the thermosetting resin be 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0024] The resin contained in the thermosetting resin sheet a preferably contains substantially no thermoplastic resin. When the thermosetting resin sheet a contains a thermoplastic resin, it is preferable that the thermoplastic resin is 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, based on 100% by mass of the resin contained in the thermosetting resin sheet a.

[0025] Also, the thermosetting resin sheet a preferably contains a thermosetting resin (including both uncured resin and cured product) as a matrix resin and is mainly composed of the thermosetting resin. Among the resin components contained in the thermosetting resin sheet a, from the viewpoint of strength, it is preferable that the thermosetting resin is 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. As the amount of the thermosetting resin contained in the thermosetting resin sheet a increases, the tack of the thermosetting resin sheet a becomes higher and it becomes easier to wind the prepreg b.

[0026] <Layer B> Layer B12 is a fiber-reinforced resin layer containing a thermoplastic resin and a continuous fiber base material. When forming layer B12 using a prepreg made of a discontinuous fiber base material instead of the continuous fiber base material, layer B12 becomes a fiber-reinforced resin layer containing a thermoplastic resin and a discontinuous fiber base material. Layer B12 is composed of a fiber-reinforced resin that is a cured product of the prepreg. The thickness of one sheet of the prepreg that becomes layer B after curing is, for example, 10 μm to 250 μm. From the viewpoint of handleability, 20 μm to 100 μm is preferable. The carbon fiber areal density in the prepreg that becomes layer B after curing is, for example, 10 g / m 2 ~300 g / m 2 is. From the viewpoint of handleability, 30 g / m 2 ~250 g / m 2 is preferable, and 50 g / m 2 ~220 g / m 2This is more preferable. As thermoplastic resins, polyetherimide, polyetheretherketone, polyetherketoneketone, polyethersulfone, polyphenylenesulfone, polyamide, polyphenylenesulfide, and polycarbonate can be used. Among these, polyetherimide is preferred in terms of improving thread strength.

[0027] Layer B12 contains a thermoplastic resin as the matrix resin, and preferably the thermoplastic resin is the main component. In layer B12, it is preferable that thermoplastic resin accounts for 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The higher the thermoplastic resin content, the better the thread cutting strength and thread breaking angle of the shaft.

[0028] If layer B12 contains a thermoplastic resin, it is preferable that the resin contained in layer B12 substantially contains no thermosetting resin. Preferably, the amount of thermosetting resin in layer B is 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to 100% by mass of the resin contained in layer B.

[0029] Prepreg b contains a thermoplastic resin as the matrix resin, and preferably has a thermoplastic resin as its main component. In prepreg b, it is preferable that the thermoplastic resin makes up 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The higher the thermoplastic resin content, the better the thread cutting strength and thread breaking angle of the shaft.

[0030] If prepreg b contains a thermoplastic resin, it is preferable that the resin contained in prepreg b substantially does not contain a thermosetting resin. The amount of thermosetting resin in prepreg b is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to 100% by mass of the resin.

[0031] The continuous fiber base material included in layer B12 is preferably a woven fabric base material or a unidirectional fiber base material. The reinforcing fibers constituting the fiber base material in layer B12 can be carbon fibers and / or glass fibers, similar to the fibers included in layer A11.

[0032] The length of the fibers is preferably 1% or more of the total length of the shaft, more preferably 10% or more, even more preferably 30% or more, particularly preferably 50% or more, even more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100%. Longer fiber lengths are preferable because they improve the tensile strength of the shaft.

[0033] Furthermore, the fiber length is preferably 10 mm or more, more preferably 25 mm or more, and even more preferably 50 mm or more. Longer fiber lengths are preferable because they improve the tensile strength of the shaft. The length of the fibers can be 1200mm or less, 1070mm or less, or 1000mm or less.

[0034] If the fibers contained in layer B12 are continuous fibers, the thickness of the fiber-reinforced resin layer can be reduced while maintaining a high fiber volume content. This makes it possible to improve thread strength and thread angle while maintaining lightness. The fiber volume content of prepreg b is preferably 10 vol% or more, more preferably 20 vol% or more, even more preferably 30 vol% or more, even more preferably 40 vol% or more, and particularly preferably 50 vol% or more. A higher fiber volume content is preferable because it improves thread strength and thread fracture strength. The fiber volume content of prepreg b is preferably 80% by volume or less, more preferably 75% by volume or less, and even more preferably 65% ​​by volume or less.

[0035] Layer B12 may be in the form of a continuous tape, toupleg, or web. The fibers contained in layer B12 may be in the form of short fibers. Short fibers may be formed by making incisions in the prepreg that will become layer B12, or a deposit of short fibers may be impregnated with a thermoplastic resin to form the prepreg that will become layer B12.

[0036] Compared to prepregs impregnated with thermoplastic resin wound by sheet wrap molding, thermoplastic fiber-reinforced resin layers molded and positioned by injection molding have a lower fiber volume content. Therefore, if a thermoplastic fiber-reinforced resin layer molded by injection molding is positioned to the same thickness as a thermoplastic-impregnated prepreg wound by sheet wrap molding, the amount of fiber decreases, resulting in a decrease in thread strength and thread failure angle. For this reason, shafts with a thermoplastic fiber-reinforced resin layer molded by injection molding require a thicker thermoplastic fiber-reinforced resin layer compared to shafts with prepregs wound by sheet wrap molding. Increasing the thickness of the thermoplastic fiber-reinforced resin layer increases the weight of the shaft. In addition, because a release agent is applied to the injection molding die and an internal release agent is added to the resin during injection molding, the thermoplastic fiber-reinforced resin layer may contain a release agent. The release agent contained in the thermoplastic fiber-reinforced resin layer molded by injection molding makes it easier for delamination to occur, making it difficult to exhibit the strength and angle characteristics in the threading test described in the examples section.

[0037] The fibrous base material included in layer B12 is preferably a unidirectional fibrous base material. A unidirectional fibrous base material allows the prepreg to be easily wound onto a mandrel, which is advantageous from a manufacturing standpoint. In the case of unidirectional fibers, when the axial direction of the shaft is set to 0°, the fiber direction can be 0°, 30°, or 45°. When winding at angles greater than 45°, the fiber length is preferably 1 / 8 or more of the shaft circumference, and more preferably 1 / 4 or more. Longer fiber lengths are preferable as they improve the thread strength and thread failure angle of the shaft. Furthermore, the fiber length is preferably 2 times or less the shaft circumference, and more preferably 1 time or less. Shorter fiber lengths make it easier to wind the prepreg.

[0038] Furthermore, the degree of orientation pf of the reinforcing fibers in layer B12 is preferably 0.5 or higher, more preferably 0.6 or higher, and even more preferably 0.7 or higher. The degree of orientation pf is an index that represents the orientation state of the reinforcing fibers in a specific direction in layer B12. A larger value of the degree of orientation pf is preferable from the viewpoint of improving thread cutting strength and thread cutting fracture angle. The fiber direction may be random.

[0039] The thickness of one layer of layer B12 is preferably 0.2 mm or less, more preferably 0.15 mm or less, and even more preferably 0.1 mm or less. The thinner the layer B12, the easier it is to maintain the lightness of the shaft. The thickness of layer B12 is usually 0.01 mm or more, and preferably 0.02 mm or more. The above upper and lower limits can be combined arbitrarily. For example, it is preferably 0.01 mm or more and 0.2 mm or less, more preferably 0.01 mm or more and 0.1 mm or less, and even more preferably 0.02 mm or more and 0.1 mm or less.

[0040] In the case of unidirectional fibers, it is preferable that the orientation direction of the fibers is the same as the axial direction of the shaft. The angle between the orientation direction of the fibers and the axial direction of the shaft is preferably ±30° or less, more preferably ±20° or less, even more preferably ±10° or less, and particularly preferably ±5° or less. The smaller the angle between the orientation direction of the fibers and the axial direction of the shaft, the easier it is to wind the sheet, which is preferable from a manufacturing standpoint. Typically, the angle between unidirectional fibers is within ±5° due to placement errors and other factors.

[0041] In the shaft 10 of this embodiment, the content of thermoplastic resin in layer B12 is preferably 0.5% to 90% by mass, more preferably 1% to 80% by mass, even more preferably 2% to 50% by mass, particularly preferably 3% to 30% by mass, particularly preferably 4% to 20% by mass, and particularly preferably 5% to 10% by mass, based on the total mass (100% by mass) of the thermosetting resin in layer A11 and the thermoplastic resin in layer B12. If the content of thermoplastic resin is above the lower limit, the thread cutting strength is improved. If the content of thermoplastic resin is below the upper limit, the moldability is improved.

[0042] The mass of layer B12 is preferably 10% by mass or less, more preferably 9% by mass or less, and even more preferably 8% by mass or less, relative to the mass of the shaft. If the mass of layer B12 is within the above range relative to the mass of the shaft, the threading strength and thread breaking angle can be improved while maintaining the lightness of the shaft. Furthermore, the mass of layer B12 is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, relative to the mass of the shaft. If the mass of layer B12 is within the above range relative to the mass of the shaft, the threading strength and thread breaking angle will be improved.

[0043] In the shaft 10 of this embodiment, it is preferable that layer B12 is distributed over 50% or more of the total length of the shaft 10, more preferably over 70%, even more preferably over 90%, and particularly preferably along the entire length. The widespread distribution of layer B12 on the shaft 10 improves the thread cutting strength. Furthermore, as shown in Figures 15 and 16, in the case of a tapered shaft, it is preferable that layer B12 be placed on the smaller diameter side, i.e., the tip side of the shaft 10 (the area indicated by hatching in Figure 15 and the area indicated by hatching in Figure 16), from the viewpoint of improving thread strength, and it is particularly preferable that it be placed along the entire length of the shaft 10, as shown in Figure 17. Note that in Figure 17, the entire area of ​​the shaft 10 is shown in hatching to indicate that layer B12 is placed along the entire length of the shaft 10. As shown in Figures 18 to 20, if layer B12 is not arranged along the entire length, layer B12 may be arranged at a distance from the tip of the shaft 10. From the viewpoint of improving thread strength, it is preferable that layer B12 is arranged closer to the tip.

[0044] According to the shaft 10 of this embodiment, it has a plurality of layers A11 and at least one layer B12, where layer A11 contains a cured product of a thermosetting resin, layer B12 contains a thermoplastic resin and a continuous fiber base material, and at least one layer B12 is arranged between two layers A11A and A11B, so that a shaft with reduced weight can be provided while maintaining high thread strength.

[0045] The shaft of this embodiment is also suitable as a sporting goods item and is suitable for use in golf-related products such as golf clubs and shafts, racket sports-related products such as tennis rackets and badminton rackets, fishing-related products such as fishing rods, ski poles, tent poles and other leisure goods, and other indoor and outdoor sports-related products. Furthermore, the shaft of this embodiment is also suitable as a power drive shaft and is suitable for use as a drive shaft or propeller shaft in automobiles, ships, and agricultural machinery, as well as a shaft for industrial equipment such as machine tools and belt conveyors. Furthermore, it is suitably used as various frames and pipes in aircraft, automobiles, bicycles, and the like. In addition to being used as a drive transmission component, the shaft may also be used as a pole, bar, or rod that does not transmit power.

[0046] [Shaft manufacturing method] The method for manufacturing a shaft according to this embodiment is a method for manufacturing a shaft having a plurality of layers A and at least one layer B, wherein layer A includes a cured product of a thermosetting resin and layer B includes a thermoplastic resin and a continuous fiber substrate, and comprises the steps of: winding a thermosetting resin sheet a which will be layer A and a prepreg b which will be layer B around the outer circumference of a mandrel in accordance with the shape of the mandrel to form a laminate of prepreg (hereinafter referred to as the "laminated body formation step"); heating the laminate (hereinafter referred to as the "heating step"); and separating the heated laminate from the mandrel (hereinafter referred to as the "separation step").

[0047] In another embodiment, the prepreg b, which will be layer B, and the thermosetting resin sheet a, which will be layer A, are wound in that order from the mandrel side. In this case, an adhesive or the like is applied to the mandrel, and the prepreg b is wound around it. Alternatively, it is preferable to have a means for fixing the prepreg, such as winding heat-shrinkable tape around the outside of the prepreg b to secure it. Having a means for fixing the prepreg allows the prepreg b to be wound even if it is not wound around the thermosetting resin sheet a.

[0048] For example, if the carbon fiber basis weight of the prepreg is 20 g / m 2 In the following cases, it is preferable to wrap the prepreg around the mandrel in layers with another prepreg.

[0049] By winding the prepreg b and thermosetting resin sheet a in that order from the mandrel side, the prepreg b comes into contact with the thermosetting resin sheet a. When the prepreg b comes into contact with the thermosetting resin sheet a, the tack of the thermosetting resin sheet a fixes the prepreg b in place. This allows the prepreg b, which has poor draping properties, to be wound around the outer circumference of the mandrel. When winding onto the mandrel, the prepreg b and thermosetting resin sheet a may be overlapped before winding, or the thermosetting resin sheet a may be wound first, followed by the prepreg b. The thermosetting resin sheet a can be one that has tack, and may be a thermosetting resin sheet, or it may be a prepreg with a thermosetting resin as the matrix resin.

[0050] Furthermore, the thermosetting resin sheet a, which is wound around the outside of the prepreg b, may be wound after forming a laminated sheet with the prepreg b, or it may be wound after winding the prepreg b. Winding a laminated sheet of prepreg b and thermosetting resin sheet a makes it easier to wind the prepreg b, which is preferable from a manufacturing standpoint. Furthermore, when a laminated sheet, formed by laminating prepreg b and thermosetting resin sheet a, is wound onto a mandrel, another prepreg b or mandrel may be in contact with the inside of one prepreg b.

[0051] Furthermore, the outer circumference of the mandrel can be anywhere outside the mandrel. For example, multiple thermosetting resin sheets a and prepreg b may be wound in the order of mandrel-thermosetting resin sheet a-thermosetting resin sheet a-prepreg b-thermosetting resin sheet a.

[0052] The mandrel may be made of metal, resin, or fiber-reinforced resin. If resin or fiber-reinforced resin is used, it may be uncured, cured, or thermoplastic. The mandrel may or may not have a tapered surface. When forming a solid shaft, after winding a sheet or prepreg around the mandrel, the shaft including the laminate and the mandrel is formed without withdrawing the mandrel. Alternatively, the mandrel may be withdrawn, and another component may be inserted to form a solid shaft.

[0053] Alternatively, the solid shaft may be constructed by placing a thermosetting resin sheet a or prepreg b in the center as a mandrel, with the thermosetting resin sheet a or prepreg b placed on the outside. When prepreg b is wound around the central thermosetting resin, it is preferable that prepreg b be positioned in contact with the thermosetting resin sheet positioned in the center. This arrangement is preferable from a manufacturing standpoint because the tack of the thermosetting resin sheet a fixes the prepreg b in place.

[0054] Layer B12 is preferably provided between the 2nd and 8th layers from the mandrel, and more preferably between the 3rd and 7th layers. Furthermore, the outermost surface of layer B12 is preferably within 50%, more preferably within 45%, and even more preferably within 40% of the thickness of the laminate from the innermost part of the laminate. Furthermore, the innermost part of layer B12 is preferably at least 5%, more preferably at least 10%, and even more preferably at least 15% from the innermost part of the laminate. Providing layer B12 within the above range allows for easy winding of prepreg b during manufacturing. When forming a solid shaft, the thickness of the laminate is the distance from the center of the shaft to the outer surface of the shaft. When forming a hollow shaft, the thickness of the laminate is the distance from the inner surface of the shaft to the outer surface of the shaft. The distance from the center of the shaft to the outermost surface of layer B12 is preferably within 50%, more preferably within 45%, and even more preferably within 40% of the thickness of the laminate. Furthermore, it is preferable that the distance from the center of the shaft to the innermost surface of layer B12 is at least 5% of the thickness of the laminate, more preferably at least 10%, and even more preferably at least 15%. By providing layer B12 within this range, the prepreg b can be easily wound during manufacturing.

[0055] By winding the thermosetting resin sheet a followed by the prepreg b, the prepreg b is fixed in place by the thermosetting resin sheet a. This allows the prepreg b to be wound around the outer circumference of the mandrel. It is preferable that the surface of prepreg b facing thermosetting resin sheet a is in direct contact with thermosetting resin sheet a. Direct contact between thermosetting resin sheet a and prepreg b strengthens the adhesion between them.

[0056] It is preferable that the contact area of ​​the thermosetting resin sheet a with respect to the area of ​​the prepreg b is 10% or more, more preferably 30% or more, even more preferably 50% or more, and even more preferably 80% or more, and it is particularly preferable that the entire prepreg b is covered with the thermosetting resin sheet a. Being within the above range is preferable from a manufacturing standpoint because the prepreg b adheres firmly to the thermosetting resin sheet a. It is also preferable because layer A11 and layer B12 are firmly bonded, improving thread cutting strength and thread cutting failure angle.

[0057] When overlapping or winding the prepreg b and the thermosetting resin sheet a, the position of the edge b1 of the prepreg b that serves as the starting point for winding around the mandrel does not have to coincide with the position of the edge a1 of the thermosetting resin sheet a that serves as the starting point for winding around the mandrel, as shown in Figures 21 and 22. Similarly, when forming a laminated sheet of thermosetting resin sheet a on the outside of the prepreg b, or forming a laminate, the position of the edge b1 of the prepreg b that serves as the starting point for winding around the mandrel does not have to coincide with the position of the edge a1 of the thermosetting resin sheet a that serves as the starting point for winding around the mandrel. It is preferable that the positions of the edge b1 of the prepreg b and the edge a1 of the thermosetting resin sheet a do not coincide, so that the overlap between the edge b1 of the prepreg b and the edge a1 of the thermosetting resin sheet a is not visible on the exterior of the shaft. If the position of the edge b1 of prepreg b and the position of the edge a1 of thermosetting resin sheet a do not coincide, it is preferable that the area in contact with the thermosetting resin sheet a relative to the area of ​​prepreg b be 10% or more, more preferably 30% or more, even more preferably 50% or more, and even more preferably 80% or more, and it is particularly preferable that the entire prepreg b is covered with thermosetting resin sheet a. Within the above range, layer B adheres more firmly to layer A, and the threading strength is improved. Similarly, the position of the edge of the thermosetting resin sheet a2, which serves as the starting point for winding around the mandrel, does not have to coincide with the position of the edge of the prepreg b, which serves as the starting point for winding around the mandrel.

[0058] Furthermore, it is preferable that at least one of the edges b1 of the prepreg b is in contact with the thermosetting resin sheet a. Here, the edges refer to the portion that is attached to the object to be wound when winding begins (winding start edge) and the portion that last comes into contact with the object to be wound when winding ends (winding end edge). In the cross-section perpendicular to the axial direction of the shaft shown in Figure 23, the ratio (L / r) of the widthwise length L of the thermosetting resin sheet a to the radius r from the center of the shaft to the outermost surface of the thermosetting resin sheet a in contact with the prepreg b is preferably 0.5 or more, more preferably 1 or more, and even more preferably π (pi) or more. Within this range, the tack of the thermosetting resin sheet a overcomes the bending rigidity of the thermosetting resin sheet a in the prepreg b, allowing the prepreg b to be wound around the sheet. The ratio of the thickness of one prepreg b to the thickness of one thermosetting resin sheet a (prepreg b / thermosetting resin sheet a) is preferably 1.3 or less, more preferably 1.2 or less, and even more preferably 1.1 or less. Furthermore, it is preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and particularly preferably 0.6 or more. Being within the above range reduces the rigidity of the prepreg b, making it easier to wind.

[0059] Furthermore, it is preferable that the length of contact between layer A11 and the shortest point of the axial length of layer B12 from the butt end to the tip end of the shaft is 10% or more of the axial length of layer B12, more preferably 30% or more, even more preferably 50% or more, even more preferably 80% or more, and particularly preferably 100%. Being within the above range is preferable because it allows layer B12 to adhere more firmly to layer A11, improving the thread cutting strength.

[0060] The ratio of the thickness of layer B12 to the thickness of layer A11 (layer B / layer A) is preferably 1.3 or less, more preferably 1.2 or less, and even more preferably 1.1 or less. It is also preferably 0.3 or more, more preferably 0.4 or more, even more preferably 0.5 or more, and particularly preferably 0.6 or more. Being within the above range reduces the bending stiffness of prepreg b, making it easier to wind.

[0061] Furthermore, it is preferable that the area of ​​layer B12 in contact with layer A11 is 10% or more, more preferably 30% or more, even more preferably 50% or more, and even more preferably 80% or more, and it is particularly preferable that the entire layer B12 is in contact with layer A11. Being within the above range is preferable because it allows layer A11 and layer B12 to bond firmly, improving thread strength and thread failure angle.

[0062] The manufacturing method for the shaft of this embodiment will be described in detail, using the sheet wrapping method as an example. Figure 24 is a schematic diagram showing the shape of the mandrel used in the manufacture of shaft 10. Prepare an iron mandrel 50 having the shape shown in Figure 24. The mandrel 50 is formed in a cylindrical shape. In the mandrel 50, the outer diameter gradually increases linearly from the small diameter end P3 to the switching point P2, and the outer diameter remains constant from the switching point P2 to the large diameter end P1.

[0063] Figure 25 is a pattern diagram showing the shape of the prepreg used in the manufacture of shaft 10. In the laminate formation process, prepregs (patterns 1 to 7) cut into the shapes shown in Figure 25 are sequentially wound around a mandrel 50 to form a laminate of prepregs, and then heat-shrinkable tape made of polypropylene, for example, is wound on top of it at a predetermined pitch.

[0064] In the prepreg pattern diagrams below, the unit "mm" is omitted for the dimensions of each pattern. The dashed arrows in each pattern indicate the orientation of the reinforcing fibers in the fiber material. The angle indicated by the dashed arrow represents the angle of orientation of the reinforcing fibers in the fiber material relative to the axial direction of the mandrel 50. If there is no dashed arrow in the pattern, it indicates that the orientation of the reinforcing fibers in the fiber material is aligned with the axial direction of the mandrel 50.

[0065] Pattern 1 is formed by layering two prepregs: one that forms an angle layer (hereinafter simply referred to as the "+45° angle layer") in which the reinforcing fibers in the fiber material are oriented at a winding angle of +45° with respect to the axial direction of the mandrel 50, and another that forms an angle layer (hereinafter simply referred to as the "-45° angle layer") in which the reinforcing fibers in the fiber material are oriented at a winding angle of -45° with respect to the axial direction of the mandrel 50, to form a bias layer (hereinafter simply referred to as the "bias layer"). Pattern 1 is wrapped around the entire surface of the mandrel 50.

[0066] Patterns 2 to 6 consist of prepregs in which reinforcing fibers in the fibrous material are oriented at a winding angle of 0° with respect to the axial direction of the mandrel 50, forming straight layers (hereinafter simply referred to as "straight layers"). Each of patterns 2 to 6 is a layer that extends along the entire length of the shaft 10.

[0067] Pattern 7 is made of a prepreg in which reinforcing fibers in the fibrous material form a straight layer oriented at a winding angle of 0° with respect to the axial direction of the mandrel 50. Pattern 7 is wrapped around the portion of the mandrel 50 corresponding to the butt end of the shaft 10. The prepregs in patterns 1, 2, and 4-7 are thermosetting resin sheets a, which form layer A. The prepreg in pattern 3 is prepreg b, which forms layer B. Furthermore, the stacking may be unidirectional, orthogonal, or pseudo-isotropic.

[0068] In the heating process, the laminate wrapped with heat-shrinkable tape is placed in a heating furnace and heated. For example, the laminate is heated to 135°C for 2 hours. The heating temperature of the laminate is set to be above the melting point of the thermoplastic resin contained in the prepreg of pattern 3. By heating the laminate, the thermoplastic resin contained in the prepreg of pattern 3 is melted, allowing the prepreg of pattern 3 to bond with the prepregs of the other patterns. The prepregs of patterns 1 to 7 are integrated by hardening or softening. After that, the prepregs of patterns 1 to 7 are allowed to cool naturally to room temperature, hardening or solidifying them to form a fiber-reinforced resin layer.

[0069] In the separation process, the shaft 10 is manufactured by removing the formed fiber-reinforced resin layer from the mandrel 50.

[0070] Afterward, the heat-shrinkable tape is removed from the shaft 10, and the surface of the shaft 10 is polished.

[0071] The shaft 10 may be completed by polishing its surface, or by applying decoration to the polished surface. In this embodiment, it is possible to appropriately select whether or not to apply decoration to the surface of the shaft 10. When decorating the shaft 10 in this embodiment, a glossy appearance can be formed on the surface of the shaft 10 by, for example, painting it by wiping or spray painting, or by transferring a transfer foil containing metal foil.

[0072] According to the shaft manufacturing method of this embodiment, it is possible to provide a shaft that is lighter in weight while maintaining high thread strength.

[0073] [Golf club shafts] The golf club shaft of this embodiment is composed of the shaft of the embodiment described above. Figure 26 is a schematic diagram of the golf club shaft of this embodiment. As shown in Figure 26, the golf club shaft (hereinafter sometimes referred to as "shaft") 100 of this embodiment is formed in a cylindrical shape. The shaft 100 is formed such that the outer diameter of the plane perpendicular to the axial direction gradually increases from one end in the axial direction (the right end in Figure 24) to the other end (the left end in Figure 24). Alternatively, the shaft 100 may be formed so that the outer diameter is the same from the diameter switching section 101 in the middle of the axial direction to the other end. Hereinafter, the end with the smaller outer diameter of the shaft 100 will be called the tip 102 (the end of the shaft 100 on the tip 102 side will be called the tip end 102a), and the end with the larger outer diameter will be called the butt 103 (the end of the shaft 100 on the butt 103 side will be called the butt end 103a). The butt 103 is the part to which the grip is attached and held, and for example, it refers to the part of the shaft 100 from the butt end 103a to the diameter switching section 101.

[0074] Since the shaft 100 of this embodiment is composed of the shaft of the above-described embodiment, it is possible to reduce the weight while maintaining high thread strength. [Examples]

[0075] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0076] [Example 1] (Shaft manufacturing) A cylindrical body made of iron was used as the mandrel. Specifically, the outer diameter d1 was kept constant at 3.10 mm from 20 mm from the end (the narrow end) to 389.3 mm in the longitudinal direction, and further expanded at a taper ratio of 10.22 / 1000 from the starting point to 1190 mm in the longitudinal direction, with an outer diameter d2 of 12.10 mm at this maximum diameter. Furthermore, prepregs (carbon prepregs: manufactured by Mitsubishi Chemical Corporation) having the shape and dimensions shown in Figure 13 and the specifications shown in Table 2 were prepared. Thermoplastic prepregs 1 to 3 were fabricated as follows. The compositions of thermoplastic prepregs 1 to 3 are shown in Table 1.

[0077] (Preparation of prepreg 1) Two 15μm thick films 1, produced by extruding polyetherimide resin (Ultem1000, manufactured by Sabic Co., Ltd.) using an extruder and T-die, and carbon fiber 1 (MR50R, manufactured by Mitsubishi Chemical Corporation) with a carbon fiber basis weight of 75g / m² were used. 2 A sheet-like carbon fiber substrate was layered with the film, and the film was heated and melted to impregnate the carbon fiber substrate, thereby producing a fiber-reinforced resin prepreg. The resulting prepreg had a carbon fiber content of approximately 58% by volume, a resin content of approximately 34% by mass, and a thickness of approximately 72 μm.

[0078] (Preparation of Prepreg 2) The aforementioned film 1 and carbon fiber 2 (Mitsubishi Chemical Corporation MR70) are used with a carbon fiber basis weight of 38 g / m². 2 A sheet-like carbon fiber substrate and the aforementioned film were layered together, and the film was heated and melted to impregnate the carbon fiber substrate, thereby producing a fiber-reinforced resin prepreg. The resulting prepreg had a carbon fiber content of approximately 58% by volume, a resin content of approximately 33% by mass, and a thickness of approximately 36 μm.

[0079] (Prepreg 3 preparation) Using an extruder and T-die, a 9 μm thick film 2 was extruded from polyetherimide resin (Ultem1000, manufactured by Savic Co., Ltd.), and carbon fiber 2 (MR70, manufactured by Mitsubishi Chemical Corporation) was added with a carbon fiber basis weight of 34 g / m². 2 A carbon fiber substrate in sheet form and the aforementioned film were layered together, and the film was heated and melted to impregnate the carbon fiber substrate, thereby producing a fiber-reinforced resin prepreg. The resulting prepreg had a carbon fiber content of approximately 68% by volume, a resin content of 25% by mass, and a thickness of approximately 28 μm.

[0080] [Table 1]

[0081] These prepregs were wound onto a mandrel, and the shaft of Example 1 was manufactured using the shaft manufacturing method described above.

[0082] [Table 2]

[0083] (evaluation) The obtained shafts were evaluated for weight (g), thread strength (torque at fracture (kgf·m)), and thread fracture angle (deg). The results are shown in Table 6.

[0084] (1) Weight The weight of the shaft was measured to two decimal places using a commercially available electronic balance (EK-300i, manufactured by A&D Company, Limited). (2) Thread strength, thread failure angle Threading strength and threading failure angle were measured using a universal tester manufactured by Mechatronics Engineering Co., Ltd. The test specimen, prepared by bonding the small diameter section of the shaft to a dedicated jig and embedding a bolt inside the large diameter section of the shaft, was set in a torsional strength measuring instrument, and measurements could be taken by applying torsional stress to the shaft. The fracture load and fracture angle at the time of fracture were read, and the torsional strength (N·m·degrees) was calculated by multiplying the fracture load by the fracture angle. The fracture angle at that time was defined as the thread failure angle.

[0085] [Example 2] As Pattern 3, the shaft of Example 2 was manufactured in the same manner as in Example 1, except that a prepreg (carbon prepreg: manufactured by Mitsubishi Chemical Corporation) with the specifications shown in Table 3 was used. The obtained shafts were evaluated for weight (g), thread strength (torque at fracture (kgf·m)), and thread fracture angle (deg). The results are shown in Table 6.

[0086] [Table 3]

[0087] [Example 3] As Pattern 3, the shaft of Example 3 was manufactured in the same manner as in Example 1, except that a prepreg (carbon prepreg: manufactured by Mitsubishi Chemical Corporation) with the specifications shown in Table 4 was used. The obtained shafts were evaluated for weight (g), thread strength (torque at fracture (kgf·m)), and thread fracture angle (deg). The results are shown in Table 6.

[0088] [Table 4]

[0089] [Comparative Example] As Pattern 3, a comparative example shaft was manufactured in the same manner as in Example 1, except that a prepreg (carbon prepreg: manufactured by Mitsubishi Chemical Corporation) with the specifications shown in Table 5 was used. The obtained shafts were evaluated for weight (g), thread strength (torque at fracture (kgf·m)), and thread fracture angle (deg). The results are shown in Table 6.

[0090] [Table 5]

[0091] [Table 6]

[0092] As shown in Table 6, the shafts of Examples 1 to 3, in which Pattern 3 contains a cured thermoplastic resin layer, were all similar in weight or lighter, and had higher thread cutting strength and thread cutting fracture angle compared to the comparative example in which all patterns contained a cured thermosetting resin layer.

[0093] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications are permitted without departing from the spirit of the present invention. The present invention is not limited by the foregoing description, but only by the appended claims. [Industrial applicability]

[0094] The shaft of the present invention can reduce weight while maintaining high thread strength. [Explanation of Symbols]

[0095] 10 shafts 11,11A,11B Layer A 12 layer B 20 Hollow part 50 Mandrels 100 shaft 101 Diameter switching section 102 chips 103 Bat a Thermosetting resin sheet b Prepreg a1 Edge of thermosetting resin sheet a b1 End of prepreg b

Claims

1. A shaft having multiple layers A and at least one layer B, The aforementioned layer A comprises a cured product of a thermosetting resin, and the aforementioned layer B comprises a thermoplastic resin and a continuous fiber substrate. At least one of the layers B is placed between the two layers A. A shaft in which the total mass of layer B is 1% by mass or more and 9% by mass or less of the total mass of the shaft.

2. The shaft according to claim 1, wherein the continuous fiber base material is a woven fabric base material or a unidirectional fiber base material.

3. The shaft according to claim 1 or 2, wherein layer A is a fiber-reinforced resin layer containing a continuous fiber base material.

4. The shaft according to claim 3, wherein the continuous fiber base material included in layer A is a woven fiber base material or a unidirectional fiber base material.

5. The shaft according to any one of claims 1 to 4, wherein the thermoplastic resin comprises polyetherimide.

6. The shaft according to any one of claims 1 to 5, wherein the thermosetting resin includes an epoxy resin.

7. The shaft according to any one of claims 1 to 6, wherein the continuous fiber base material contained in the layer B contains carbon fibers.

8. The shaft according to any one of claims 1 to 7, wherein the content of the thermoplastic resin is 1% by mass or more and 80% by mass or less based on the total mass of the thermosetting resin and the thermoplastic resin.

9. The shaft according to any one of claims 1 to 8, wherein the ratio of the thickness of layer B to the sum of the thicknesses of layer A and layer B (thickness of layer B / sum of the thicknesses of layer A and layer B) is 0.5% or more and 90% or less.

10. The shaft according to any one of claims 1 to 9, wherein the shaft is hollow.

11. The shaft according to any one of claims 1 to 10, wherein layer A is arranged as the outermost layer.

12. The shaft according to claim 11, wherein the layers are arranged in the order of layer A - layer B - layer A.

13. A golf club shaft comprising the shaft described in any one of claims 1 to 12.

14. A method for manufacturing a shaft, comprising a plurality of layers A and at least one layer B, wherein layer A includes a cured product of a thermosetting resin and layer B includes a thermoplastic resin and a continuous fiber substrate, The total mass of layer B is 1% by mass or more and 9% by mass or less of the total mass of the shaft. A step of forming a laminate of prepregs by winding a thermosetting resin sheet a, which will be layer A, and a prepreg b, which will be layer B, around the outer circumference of a mandrel, following the shape of the mandrel, in the order of prepreg b, then thermosetting resin sheet a, starting from the mandrel side. The process of heating the laminate, A method for manufacturing a shaft, comprising the step of separating the heated laminate from the mandrel.

15. The method for manufacturing a shaft according to claim 14, wherein the layer B is arranged between two of the layers A.

16. The method for manufacturing a shaft according to claim 14 or 15, wherein the shaft is hollow.

17. The method for manufacturing a shaft according to claim 16, wherein the layer B is arranged on the hollow side of at least one of the layers A.

18. A process of forming a laminate of prepregs by winding a thermosetting resin sheet a containing thermosetting resin and fibers, and a prepreg b containing thermoplastic resin and fibers, around the outer circumference of a mandrel, following the shape of the mandrel, in the order of prepreg b, then thermosetting resin sheet a, starting from the mandrel side. The process includes heating the laminate, A method for manufacturing a shaft, wherein the total mass of the prepreg b is 1% by mass or more and 9% by mass or less of the total mass of the shaft.

19. The process involves winding a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers around the outer circumference of a mandrel, following the shape of the mandrel, so that the thermosetting resin sheet a and the prepreg b are in that order from the mandrel side, thereby forming a laminate including the portion where the thermosetting resin sheet a and the prepreg b are in contact. A method for manufacturing a shaft, wherein the total mass of the prepreg b is 1% by mass or more and 9% by mass or less of the total mass of the shaft.

20. A method for manufacturing a shaft according to claim 19, comprising the step of heating the laminate.

21. The process involves winding a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers around the outer circumference of a mandrel, following the shape of the mandrel, in the order of thermosetting resin sheet a and prepreg b from the mandrel side, and winding the prepreg b so that it is in direct contact with the thermosetting resin sheet a, thereby forming a laminate of the thermosetting resin sheet a and the prepreg b. A method for manufacturing a shaft, wherein the total mass of the prepreg b is 1% by mass or more and 9% by mass or less of the total mass of the shaft.

22. The process includes a step of forming a wound body by winding a laminated sheet, which is made by laminating a thermosetting resin sheet a containing a thermosetting resin and a prepreg b containing a thermoplastic resin and fibers, around the outer circumference of a mandrel, following the shape of the mandrel. A method for manufacturing a shaft, wherein the total mass of the prepreg b is 1% by mass or more and 9% by mass or less of the total mass of the shaft.

23. The method for manufacturing a shaft according to claim 22, wherein when winding the laminated sheet, the thermosetting resin sheet a is wound so that it is positioned on the inside of the shaft.

24. A method for manufacturing a shaft according to claim 22 or 23, comprising the step of heating the winding body.

25. A method for manufacturing a shaft according to any one of claims 22 to 24, further comprising the step of winding a thermosetting resin sheet a2, which is different from the thermosetting resin sheet a, around the shaft around which the laminated sheet is wound.

26. A method for manufacturing a shaft according to any one of claims 22 to 25, wherein the laminated sheet is wound so that the thermosetting resin sheet a - prepreg b order from the mandrel side.

27. The method for manufacturing a shaft according to claim 22, wherein the laminated sheet further includes the thermosetting resin sheet a, and the laminated sheet is wound so that the order from the mandrel side is the thermosetting resin sheet a - the prepreg b - the thermosetting resin sheet a.

28. A method for manufacturing a shaft according to any one of claims 22 to 27, wherein the position of the edge of the thermosetting resin sheet a which serves as the starting point for winding around the outer circumference of the mandrel is different from the position of the edge of the prepreg b which serves as the starting point for winding around the outer circumference of the mandrel.

29. A method for manufacturing a shaft according to any one of claims 25 to 28, wherein the position of the edge of the thermosetting resin sheet a2 which serves as the starting point for winding around the outer circumference of the mandrel is different from the position of the edge of the prepreg b which serves as the starting point for winding around the outer circumference of the mandrel.

30. A method for manufacturing a shaft according to any one of claims 22 to 29, wherein the area in contact between the thermosetting resin sheet a and the prepreg b is 10% or more of the area of ​​the prepreg b.

31. The method for manufacturing a shaft according to any one of claims 22 to 30, wherein the thermosetting resin sheet a contains fibers.

32. A method for manufacturing a shaft according to any one of claims 22 to 31, wherein the fiber volume fraction of the fibers contained in the prepreg b is 30 volume% or more.

33. A method for manufacturing a shaft according to any one of claims 22 to 32, wherein the ratio of the thickness of one prepreg b to the thickness of one thermosetting resin sheet a (thickness of prepreg b / thickness of thermosetting resin sheet a) is 1.5 or less.

34. A method for manufacturing a shaft according to any one of claims 22 to 33, wherein the length of the fibers contained in the prepreg b is 1% or more of the length of the shaft.

35. A method for manufacturing a shaft according to any one of claims 22 to 34, wherein the ratio of the length of the thermosetting resin sheet a in the width direction to the radius of the shaft (length of the thermosetting resin sheet a in the width direction / radius of the shaft) is 0.5 or more.

36. The method for manufacturing a shaft according to any one of claims 22 to 35, wherein the thermosetting resin contained in the thermosetting resin sheet a is an epoxy resin.

37. The method for manufacturing a shaft according to any one of claims 22 to 36, wherein the thermoplastic resin contained in the prepreg b is polyetherimide.

38. The method for manufacturing a shaft according to claim 31, wherein the fibers contained in the thermosetting resin sheet a include carbon fibers.

39. A method for manufacturing a shaft according to any one of claims 22 to 38, wherein the fibers contained in the prepreg b include carbon fibers.

40. The method for manufacturing a shaft according to any one of claims 22 to 39, wherein the prepreg b is positioned within 50% of the innermost part of the laminated sheet relative to the thickness of the laminated sheet.

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