Golf club shaft, golf club, and method of manufacturing golf club shaft

Abstract

To provide a golf club shaft having light weight, exhibiting impact absorption properties in impact of a golf ball for suppressing vibration.SOLUTION: A golf club shaft has a shaft main body extending in a longitudinal direction, the shaft main body has: a first member having a fiber reinforced plastic; and a second member which is formed to directly contact the first member on at least a partial area on the first member and includes a rubber material, where the first and second members are formed of an integrated composite material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a golf club shaft made of a composite material containing fiber-reinforced plastic and rubber material, a golf club using the golf club shaft, and a method for manufacturing the golf club shaft. [Background technology]

[0002] Steel, fiber-reinforced plastic (FRP), etc. are used as materials for golf club shafts because of their light weight and strength. One proposed steel golf club shaft includes a shaft body, a coating formed by chemically treating the outer and inner surfaces of the shaft body, a coating layer formed by electrodeposition coating on at least the outer coating, and a pigment layer in which polarizing powder is dispersed, which is applied to the coating layer (Patent Document 1).

[0003] In Patent Document 1, a pigment layer with polarizing powder dispersed therein is formed on a coating layer formed by electrodeposition coating on a chemical conversion coating, which results in a golf club shaft that is more aesthetically pleasing than conventional plated golf club shafts, has anti-corrosion effects on the inside of the shaft, and is lightweight, avoiding the problem of increased weight caused by plating.

[0004] On the other hand, fiber reinforced plastics (FRP) have recently been widely used as a golf club shaft material to replace steel because of their light weight and high strength. As a golf club shaft using fiber reinforced plastic, for example, a golf club shaft has been proposed that is made of carbon fiber reinforced plastic consisting of a laminate of multiple resin-impregnated carbon fiber layers, with resin layers formed from an epoxy resin composition disposed between the resin-impregnated carbon fiber layers (Patent Document 2).

[0005] Patent Document 2 states that by placing an epoxy resin layer between resin-impregnated fiber layers, delamination between the resin-impregnated fiber layers is suppressed without reducing the elastic modulus of the golf club shaft made of fiber-reinforced plastic, thereby improving the strength of the golf club shaft made of fiber-reinforced plastic.

[0006] On the other hand, golf clubs are required to not only be lightweight and strong, but also to have a clear feel when hit. In order for a golf club to have a clear feel when hit, the golf club shaft must exhibit shock absorption properties and suppress vibration of the golf club shaft when impacted with a golf ball. The golf club shaft of Patent Document 1, which is made of steel, and the golf club shaft of Patent Document 2, which is made of fiber-reinforced plastic layers and epoxy resin layers disposed between the fiber-reinforced plastic layers, have room for improvement in terms of suppressing vibration of the golf club shaft when impacted with a golf ball and providing a clear feel when hit by the golf club. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-246824 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-87460 Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above circumstances, an object of the present invention is to provide a golf club shaft that is lightweight and exhibits shock absorbing properties to suppress vibrations upon impact with a golf ball, a golf club including the golf club shaft, and a method for manufacturing the golf club shaft. [Means for solving the problem]

[0009] The gist of the configuration of the present invention is as follows. [1] A golf club shaft having a shaft body extending in a longitudinal direction, A golf club shaft in which the shaft body comprises a first member having a fiber-reinforced plastic and a second member having a rubber material formed in direct contact with the first member in at least a portion of the first member, the first member and the second member being constructed from a composite material in which the first member and the second member are integrated. [2] A golf club shaft according to [1], wherein a portion of the first member and the second member are in direct contact with each other, and no adhesive member is interposed between the first member and the second member. [3] The golf club shaft according to [1] or [2], wherein the first member and the second member are in the form of sheets, and the composite material has a laminate structure. [4] The golf club shaft according to any one of [1] to [3], wherein the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, butyl rubber, ethylene propylene diene rubber, hydrogenated nitrile rubber, and silicone rubber. [5] The golf club shaft according to any one of [1] to [4], wherein the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, and butyl rubber. [6] The golf club shaft according to any one of [1] to [5], wherein the fiber reinforced plastic is carbon fiber reinforced plastic. [7] A golf club shaft described in any one of [1] to [6], wherein the first member is a multilayer structure having a first fiber-reinforced plastic forming a first layer having a fiber orientation angle in a first direction, and a second fiber-reinforced plastic forming a second layer having a fiber orientation angle in a second direction different from the first direction. [8] The golf club shaft according to any one of [1] to [7], wherein the outer surface of the composite material is the first member. [9] A golf club shaft according to any one of [1] to [8], wherein the shaft body has, in order from the base end to the tip end in the longitudinal direction, a first region in which the shaft outer diameter decreases relatively gradually, a second region in which the shaft outer diameter decreases relatively sharply, and a third region in which the relative amount of change in the shaft outer diameter is smallest.

[10] A golf club comprising a club head and a grip attached to the golf club shaft according to any one of [1] to [9].

[11] A step of preparing a first precursor, which is an uncured or semi-cured material in which fibers are impregnated with a resin; a step of directly laminating a second precursor having unvulcanized rubber on at least a partial area of ​​the prepared first precursor to obtain a laminate of the first precursor and the second precursor; winding the obtained laminate around an outer peripheral surface of a mandrel; a step of heat-treating the laminate wound on the outer peripheral surface of the mandrel to thermally cure the resin of the first precursor to obtain a first member having a fiber-reinforced plastic and vulcanizing the unvulcanized rubber of the second precursor to obtain a second member having a rubber material, and integrating the first member and the second member to obtain a wound composite material; withdrawing the mandrel from the wound composite material; A method for manufacturing a golf club shaft having the following structure:

[12] A method for manufacturing a golf club shaft according to

[11] , wherein the second precursor having unvulcanized rubber mixed with a vulcanizing agent is laminated directly onto the prepared first precursor without using an adhesive member. [Effects of the Invention]

[0010] According to one aspect of the golf club shaft of the present invention, there is provided a golf club shaft having a shaft body extending in the longitudinal direction of the golf club, the shaft body comprising a first member having multiple laminated fiber-reinforced plastic layers and a second member having a rubber material formed in direct contact with the first member at least in a partial area of ​​the first member. The first member and the second member are integrated into a composite material, whereby the second member having a rubber material has vibration damping properties, and the shaft body exhibits shock absorption properties upon impact with a golf ball, thereby suppressing vibration of the golf club shaft. Therefore, according to this aspect of the golf club shaft, a clear hitting feel can be imparted to the golf club. Furthermore, according to another aspect of the golf club shaft of the present invention, the composite material constituting the golf club shaft includes a first member having multiple laminated fiber-reinforced plastic layers, thereby providing light weight and strength. Furthermore, according to another aspect of the golf club shaft of the present invention, the composite material constituting the golf club shaft comprises a first member having multiple laminated fiber-reinforced plastic layers and a second member having a rubber material, thereby preventing delamination between the first member and the second member.

[0011] According to an embodiment of the golf club shaft of the present invention, a portion of the multiple laminated first members is in direct contact with the second member, and no adhesive member is interposed between the first member and the second member, thereby preventing uneven adhesion caused by the adhesive member, and reliably preventing peeling between the first member and the second member.

[0012] According to an embodiment of the golf club shaft of the present invention, the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, butyl rubber, ethylene propylene diene rubber, hydrogenated nitrile rubber, and silicone rubber, thereby obtaining adhesion between the first member and the second member and further preventing peeling.

[0013] According to an embodiment of the golf club shaft of the present invention, the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, and butyl rubber, thereby ensuring adhesion between the first and second members and further preventing separation.

[0014] In one embodiment of the method for manufacturing a golf club shaft of the present invention, a second precursor having unvulcanized rubber is directly laminated onto at least a portion of a first precursor, which is an uncured or semi-cured material having resin impregnated fibers, to obtain a laminate, and the laminate is then heat-treated to thermoset the resin in the first precursor to obtain a first component having fiber-reinforced plastic, and vulcanize the unvulcanized rubber in the second precursor to obtain a second component having a rubber material, and the first component and the second component are integrated together. That is, the laminate is heat-treated to thermoset the prepreg, which is an uncured or semi-cured material having resin impregnated fibers, and further vulcanize the unvulcanized rubber to simultaneously obtain fiber-reinforced plastic and a vulcanized rubber material, and the resulting fiber-reinforced plastic and vulcanized rubber material are integrated together.

[0015] Therefore, according to an embodiment of the golf club shaft manufacturing method of the present invention, bonding a first component having fiber-reinforced plastic and a second component having rubber material does not require an adhesive application process, nor does it require uniform application of the adhesive. As described above, the manufacturing method of the present invention can prevent the manufacturing process of a composite material of fiber-reinforced plastic and rubber material from becoming complicated, thereby facilitating the manufacture of golf club shafts. Furthermore, according to an embodiment of the golf club shaft manufacturing method of the present invention, by heat-treating the laminate, the resin of the first precursor is thermoset to obtain a first component having fiber-reinforced plastic, and the unvulcanized rubber of the second precursor is vulcanized to obtain a second component having rubber material, and the first component and the second component are integrated, thereby preventing delamination between the first component and the second component. As a result, a golf club shaft can be manufactured that is lightweight and high-strength, while exhibiting shock-absorbing properties and suppressing vibration upon impact with a golf ball.

[0016] According to an embodiment of the golf club shaft manufacturing method of the present invention, by laminating the second precursor having unvulcanized rubber directly onto the first precursor without using an adhesive member, uneven adhesion caused by the adhesive member can be prevented, and peeling between the first and second members can be reliably prevented. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an explanatory diagram showing an outline of a side surface of a golf club equipped with a golf club shaft according to an embodiment of the present invention; [Figure 2] 1 is an explanatory diagram showing an outline of a portion of an embodiment of a composite material that constitutes a shaft body of a golf club shaft according to an embodiment of the present invention. FIG. [Figure 3] 1 is an explanatory diagram showing an outline of the front surface of a tip of a golf club shaft according to an embodiment of the present invention; [Figure 4] 10 is a graph showing vibration test results of the golf club shaft of the example and the golf club shaft of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0018] The golf club shaft of the present invention will be described in detail below. Fig. 1 is an explanatory diagram showing an outline of the side of a golf club equipped with a golf club shaft according to an embodiment of the present invention. Fig. 2 is an explanatory diagram showing an outline of an embodiment of a composite material constituting the shaft body of a golf club shaft according to an embodiment of the present invention. Fig. 3 is an explanatory diagram showing an outline of the front of the tip of a golf club shaft according to an embodiment of the present invention.

[0019] As shown in FIG. 1, the golf club 50 has a golf club shaft 100 extending in the longitudinal direction, a club head 200 attached to the tip end (tip side) of the golf club shaft 100, and a grip 300 attached to the base end (butt side) of the golf club shaft 100.

[0020] The golf club shaft 100 has a shaft body 110 extending in the longitudinal direction. The shaft body 110 is a hollow cylindrical member. The golf club shaft 100 is structured so that the outer diameter of the shaft body 110 decreases at a predetermined taper rate from the base end side (butt side) to the tip end side (tip side).

[0021] As shown in FIG. 2 , the shaft body 110 includes a first member 10 having a fiber-reinforced plastic and a second member 20 having a rubber material formed in direct contact with the first member 10 in at least a partial region of the first member 10, and is configured as a composite material 1 of fiber-reinforced plastic and a rubber material, in which the first member 10 and the second member 20 are integrated. The composite material 1 constituting the shaft body 110 is integrated with the second member 20, forming a joint 30 where the first member 10 is joined to the second member 20, and the first member 10 and the second member 20 are integrated. The composite material 1 is integrated with the second member 20 in a state where at least a partial region of the first member 10 is in direct contact with the first member 10. Furthermore, the composite material 1 constituting the shaft body 110 includes the first member 10 having a fiber-reinforced plastic disposed on both sides of the second member 20 having a rubber material. Thus, the second component 20 comprising the rubber material is interposed between the first components 10 comprising the fiber reinforced plastic.

[0022] 2, in the composite material 1 constituting the shaft body 110, at the joint 30 where the first member 10 and the second member 20 are in direct contact, no adhesive material such as an adhesive is interposed between the first member 10 and the second member 20. In the composite material 1, it is sufficient that at least a portion of the area on the first member 10 is in direct contact with the second member 20 and is integrated with the second member 20, and it is sufficient that at least a portion of the area on the second member 20 is in direct contact with the first member 10 and is integrated with the first member 10.

[0023] In the composite material 1, substantially the entire surface of the first member 10 facing the second member 20 is bonded to the second member 20 in a state of direct contact with the second member 20. Furthermore, substantially the entire surface of the second member 20 facing the first member 10 is bonded to the first member 10 in a state of direct contact with the first member 10. Therefore, in the composite material 1, no adhesive member is interposed over the entire joint 30 where the first member 10 and the second member 20 face each other.

[0024] In the composite material 1, which is the material that constitutes the shaft body 110, a portion of the matrix in and around the surface of the fiber-reinforced plastic that constitutes the first member 10 penetrates into and around the surface of the rubber material that constitutes the second member 20, and a portion of the surface of and around the rubber material that constitutes the second member 20 penetrates into and around the surface of the fiber-reinforced plastic that constitutes the first member 10, so that the first member 10 is joined to the second member 20 to form a joint 30, and the first member 10 and the second member 20 are integrated together. In other words, at the joint 30 of the composite material 1, the first member 10 exerts an anchor effect on the second member 20, and the second member 20 exerts an anchor effect on the first member 10, so that the first member 10 and the second member 20 are integrated together.

[0025] The composite material 1 constituting the shaft body 110 has a sheet-like shape for both the first member 10 and the second member 20. Therefore, the composite material 1 has a sheet-like laminate structure.

[0026] The composite material 1 is a composite material of fiber-reinforced plastic and rubber, comprising a first member 10 having a fiber-reinforced plastic and a second member 20 having a rubber material that is in direct contact with the first member 10 over at least a portion of the surface of the first member 10. The first member 10 and the second member 20 are integrated by the anchor effect, preventing delamination between the first member 10 having the fiber-reinforced plastic and the second member 20 having the rubber material. Since the shaft body 110 is made of the composite material 1, the second member 20 having the rubber material of the composite material 1 has vibration damping properties. Therefore, upon impact with a golf ball, the shaft body 110 exhibits shock absorption properties, thereby suppressing vibration of the golf club shaft 100. Therefore, according to this embodiment of the golf club shaft 100 of the present invention, a clear hitting feel can be imparted to the golf club 50. Furthermore, according to an embodiment of the golf club shaft 100 of the present invention, the composite material 1 constituting the shaft body 110 is formed by firmly integrating the first member 10 having fiber-reinforced plastic and the second member 20 having rubber material, thereby preventing separation between the first member 10 and the second member 20.

[0027] Furthermore, in the composite material 1, the first member 10 and the second member 20 are in direct contact over the entire joint 30, and no adhesive member is interposed between the first member 10 and the second member 20, thereby preventing uneven adhesion caused by the adhesive member, and reliably preventing peeling between the first member 10 and the second member 20.

[0028] Examples of fiber-reinforced plastics that make up the first member 10 include carbon fiber-reinforced plastics (CFRP), glass fiber-reinforced plastics (GFRP), aramid fiber-reinforced plastics (AFRP), and cellulose fiber-reinforced plastics. Of these, carbon fiber-reinforced plastics are preferred because they have the light weight and high strength that are suitable for the golf club shaft 100. The resin component used as the matrix resin of the fiber-reinforced plastic is not particularly limited. Specific examples include thermosetting resins such as epoxy resins, phenolic resins, cyanate resins, vinyl ester resins, and unsaturated polyester resins. The fiber-reinforced plastic that makes up the first member 10 is a member obtained by thermally curing, by heat treatment or the like, uncured (or semi-cured) thermosetting prepreg, which is an intermediate material in which fibers are impregnated with a matrix resin.

[0029] As shown in FIG. 2, in the composite material 1, the first member 10 is a multilayer structure having a first fiber-reinforced plastic layer 11 (11-1) having a fiber orientation angle in a first direction and a second fiber-reinforced plastic layer 11 (11-2) having a fiber orientation angle in a second direction different from the first direction. By making the first member 10 a fiber-reinforced plastic structure having multiple layers with different fiber orientation angles, the strength of the first member 10 in the entire in-plane direction is improved. Note that, for convenience of explanation, in FIG. 2, the first member 10 is shown as a multilayer structure consisting of two fiber-reinforced plastic layers 11. However, in order to achieve a balance between lightness and strength suitable for the golf club shaft 100, the first member 10 may be a multilayer structure having three or more fiber-reinforced plastic layers 11. In the case of a multilayer structure having three or more fiber-reinforced plastic layers 11, in addition to the first fiber-reinforced plastic layer 11 and the second fiber-reinforced plastic layer 11, further fiber-reinforced plastic layers 11 with mutually different fiber orientation angles may be provided, such as a third fiber-reinforced plastic layer 11 whose fiber orientation angle is in a third direction different from both the first and second directions, or a fourth fiber-reinforced plastic layer 11 whose fiber orientation angle is in a fourth direction different from the first, second, and third directions. Furthermore, the first member 10 may be a structure consisting of a single fiber-reinforced plastic layer 11, if necessary, in terms of lightness suitable for the golf club shaft 100.

[0030] Examples of rubber materials constituting the second member 20, which primarily provides the shaft body 110 with shock-absorbing properties, include nitrile rubber (NBR) such as acrylonitrile butadiene rubber, fluororubber (FKM), butyl rubber (IIR), ethylene propylene diene rubber (EPDM), hydrogenated nitrile rubber (HNBR), silicone rubber, urethane rubber, acrylic rubber (ACM), isoprene rubber (IR), styrene rubber (SBR), butadiene rubber (BR), ethylene propylene rubber (EPM), chloroprene rubber (CR), chlorinated polyethylene, and natural rubber (NR). These rubber materials may be used alone or in combination. The rubber material constituting the second member 20 is a member obtained by vulcanizing unvulcanized rubber through heat treatment or the like.

[0031] Of these rubber materials, nitrile rubber, fluororubber, butyl rubber, ethylene propylene diene rubber, hydrogenated nitrile rubber, and silicone rubber are preferred because they can ensure adhesion between the first member 10 and the second member 20 and impart even greater strength to the shaft body 110, and nitrile rubber, fluororubber, and butyl rubber are particularly preferred because they can reliably ensure adhesion between the first member 10 and the second member 20 and impart even greater strength to the shaft body 110.

[0032] In addition to the rubber material, a vulcanizing agent is blended into the second member 20. Depending on the conditions of use of the shaft body 110, various additives such as antioxidants, processing aids, tackifiers, vulcanization accelerators, fillers, plasticizers, and vulcanization accelerators may be blended as needed in addition to the rubber material blended with the vulcanizing agent.

[0033] The specific laminate structure of the first member 10 and the second member 20 in the composite material 1 constituting the shaft body 110 will be described. The composite material 1 constituting the shaft body 110 has a laminate structure in which the first member 10 is disposed on at least the outer surface of the outer and inner surfaces that form the main surfaces of the composite material 1. That is, the outer surface of the shaft body 110 is the first member 10 of the composite material 1 that has fiber-reinforced plastic. A layer of the second member 20 having a rubber material is, for example, interposed between layers of the first member 10 having fiber-reinforced plastic. One or more layers of the second member 20 having a rubber material may be provided, and a layer of the first member 10 consisting of a single or multiple fiber-reinforced plastic layers 11 may be further interposed between the layers of the second member 20. The number of layers of the first member 10, the number of layers of the fiber-reinforced plastic layers 11, and the number of layers of the second member 20 in the composite material 1 can be selected as appropriate depending on the conditions of use of the shaft body 110, the required performance, etc. However, it is preferable that the second member 20 is placed between the layers of the first member 10, rather than as the outermost or innermost layer of the shaft body 110.

[0034] In a shaft body 110 made of a composite material 1 in which the outer surface of the composite material 1 is the first member 10 and layers of the second member 20 made of a rubber material are interposed between the layers of the first member 10, the amount of deformation until fracture due to flexure, bending, etc. increases, improving the deformation resistance of the shaft body 110. In addition, in a shaft body 110 made of a composite material 1 in which the outer surface of the composite material 1 is the first member 10 and layers of the second member 20 are interposed between the layers of the first member 10, the vibration damping properties are improved.

[0035] The shaft body 110 has a first region, a second region, and a third region, in that order from the base end to the tip end in the longitudinal direction of the shaft body 110. In the first region, the shaft outer diameter of the shaft body 110 decreases relatively gradually from the base end to the tip end in the longitudinal direction. In the second region, the shaft outer diameter of the shaft body 110 decreases relatively steeply from the base end to the tip end in the longitudinal direction. In the third region, the relative amount of change in the shaft outer diameter of the shaft body 110 in the longitudinal direction is smallest. The third region is, for example, substantially straight. A grip 300 is attached to the outer peripheral surface of the first region of the shaft body 110.

[0036] Next, a method for manufacturing the golf club shaft of the present invention will be described. The golf club shaft of the present invention has the first member 10 having the above-mentioned fiber-reinforced plastic, and the second member 20 having a rubber material formed in direct contact with the first member 10, and uses a composite material 1 of fiber-reinforced plastic and rubber material in which the first member 10 and the second member 20 are integrated.

[0037] The method for manufacturing a golf club shaft of the present invention includes the steps of: (1) preparing a first precursor, which is an uncured or semi-cured material having resin-impregnated fibers; (2) directly laminating a second precursor having unvulcanized rubber onto at least a portion of the first precursor to obtain a laminate of the first precursor and the second precursor; (3) winding the resulting laminate around the outer circumferential surface of a mandrel; (4) heat-treating the laminate wound around the outer circumferential surface of the mandrel together with the mandrel to thermoset the resin of the first precursor to obtain a first member 10 having fiber-reinforced plastic and a second member 20 having a rubber material by vulcanizing the unvulcanized rubber of the second precursor; and (5) removing the mandrel from the wound composite material 1. The above-described method for manufacturing a golf club shaft of the present invention is a method known as a sheet winding method.

[0038] (1) A step of preparing a first precursor, which is an uncured or semi-cured material in which fibers are impregnated with a resin. This is a process of preparing a prepreg (i.e., a first precursor), which is an uncured or semi-cured material made by impregnating reinforcing fibers such as carbon fibers with a resin such as a thermosetting resin. The first precursor may be a single-layer prepreg, or a laminated prepreg made by stacking multiple prepregs. The number of prepreg layers can be selected appropriately depending on the usage conditions and required performance of the golf club shaft.

[0039] (2) A step of directly laminating a second precursor having unvulcanized rubber onto the first precursor to obtain a laminate. This is a process for obtaining a laminate by laminating a second precursor having unvulcanized rubber on the surface of a (laminated) prepreg, which is a first precursor. In this process, the second precursor having unvulcanized rubber is laminated directly onto the first precursor without using an adhesive member. When laminating the second precursor onto the first precursor, the laminate of the first precursor and the second precursor may be subjected to, for example, pressing, if necessary. The laminate obtained in this process is a precursor for a composite material.

[0040] (3) A step of winding the obtained laminate around the outer circumferential surface of a mandrel. A mandrel is prepared, the outer diameter of which includes a relatively gently tapered surface for forming the first region, a relatively steeply tapered surface for forming the second region, and a portion where the relative amount of change is smallest for forming the third region. Next, a laminate in which the second precursor is laminated on the first precursor is wound around the outer peripheral surface of the mandrel.

[0041] (4) Step of obtaining wound composite material 1 In the process of obtaining the wound composite material 1, a laminate formed by laminating a first precursor and a second precursor is wound around the outer circumferential surface of a mandrel, and a heat-shrinkable tape or the like is spirally wrapped around the longitudinal direction of the laminate, followed by a heat treatment. Heat treatment of the laminate thermosets the resin of the first precursor, forming a fiber-reinforced plastic from the prepreg to obtain a first component 10 having the fiber-reinforced plastic. Further, the unvulcanized rubber of the second precursor is vulcanized to obtain a second component 20 having a rubber material. The first component 10 and the second component 20 are then integrated to obtain the wound composite material 1. That is, in the process of obtaining the wound composite material 1, a laminate of the first precursor and the second precursor is heat-treated to thermoset the prepreg, an uncured or semi-cured material in which fibers are impregnated with resin, and further, the unvulcanized rubber is vulcanized to simultaneously obtain a fiber-reinforced plastic and a vulcanized rubber material, and the resulting fiber-reinforced plastic and vulcanized rubber material are integrated. When forming a fiber-reinforced plastic from the prepreg, a portion of the resin constituting the first precursor penetrates into the unvulcanized rubber constituting the second precursor, and when vulcanizing the unvulcanized rubber to form a rubber material, a portion of the unvulcanized rubber constituting the second precursor penetrates into the resin constituting the first precursor. The interaction between the first precursor and the second precursor described above bonds the first member 10 and the second member 20 to form a joint 30, integrating the first member 10 and the second member 20. As a result, a portion of the matrix resin on the surface and its vicinity of the fiber-reinforced plastic constituting the first member 10 penetrates into the surface and its vicinity of the rubber material constituting the second member 20, and a portion of the surface and its vicinity of the rubber material constituting the second member 20 penetrates into the surface and its vicinity of the fiber-reinforced plastic constituting the first member 10, forming a joint 30. This wound composite material 1 becomes the golf club shaft 100.

[0042] As a method for heat-treating the laminate of the first precursor and the second precursor, heat-treating conditions suitable for the first precursor can be appropriately selected.

[0043] (5) Mandrel removal process The mandrel is pulled out from the wound composite material 1, and the mandrel is removed from the composite material 1, whereby the golf club shaft 100 of the present invention can be manufactured.

[0044] According to an embodiment of the golf club shaft manufacturing method of the present invention, the process of integrating the first component 10 having fiber-reinforced plastic and the second component 20 having rubber material does not require the application of an adhesive, and therefore uniform application of the adhesive is not required. As described above, the manufacturing process of the composite material 1 of fiber-reinforced plastic and rubber material can be prevented from becoming complicated, and the manufacturing of the golf club shaft 100 can be simplified. Furthermore, in the golf club shaft manufacturing method of the present invention, a laminate of the first precursor and the second precursor is heat-treated to thermoset the resin of the first precursor to obtain the first component 10 having fiber-reinforced plastic and vulcanize the unvulcanized rubber of the second precursor to obtain the second component 20 having rubber material, and the first component 10 and the second component 20 are firmly integrated. Therefore, a composite material 1 of fiber-reinforced plastic and rubber material can be prepared in which delamination between the first component 10 having fiber-reinforced plastic and the second component 20 having rubber material is prevented. As a result, it is possible to manufacture a golf club shaft 100 that is lightweight and has high strength, and that exhibits shock absorbing properties and suppresses vibrations upon impact with a golf ball.

[0045] Furthermore, according to an embodiment of the golf club shaft manufacturing method of the present invention, by laminating unvulcanized rubber directly onto the first precursor without using an adhesive member, uneven adhesion caused by the adhesive member can be prevented, and therefore peeling between the first member 10 and the second member 20 can be prevented. [Example]

[0046] Next, examples of the golf club shaft of the present invention will be described, but the golf club shaft of the present invention is not limited to the following examples. Fig. 4 is a graph showing the vibration test results of the golf club shaft of the example and the golf club shaft of the comparative example.

[0047] <Example> A prepreg, a semi-cured material made by impregnating carbon fiber with a thermosetting resin, was used as the first precursor. Unvulcanized nitrile rubber was layered on the first precursor as the second precursor, and the first precursor was then layered on the second precursor to prepare a laminate (a laminate of the first precursor and the second precursor) in which layers of the second precursor were sandwiched between layers of the first precursor. The resulting laminate was wound around the outer surface of a mandrel and heat-treated at 130°C for 90 minutes to obtain a composite material in which the wound first member having fiber-reinforced plastic and the second member having a rubber material were integrated. The mandrel was then removed from the wound composite material to produce a golf club shaft composed of the composite material.

[0048] <Comparative Example> Instead of a golf club shaft made of composite material, a steel golf club shaft was used.

[0049] Vibration Test For the golf club shafts of the example and comparative example, both ends were left as free ends, a sensor was attached to the upper part, and a vibration test was carried out by vibrating the lower part. The results of the vibration test are shown in Figure 4.

[0050] As shown in Figure 4, in the example using a golf club shaft made of a composite material in which a first member having fiber-reinforced plastic and a second member having rubber material are integrated, it was found that the golf club shaft exhibits shock absorbing properties, which suppress vibrations upon impact with a golf ball, allowing the golf club to produce a clear feel. On the other hand, in the comparative example using a steel golf club shaft, it was found that the golf club shaft does not exhibit sufficient shock absorbing properties, and is unable to exhibit shock absorbing properties upon impact with a golf ball, preventing the golf club from producing a clear feel. [Industrial Applicability]

[0051] The golf club shaft and golf club of the present invention are highly useful in that they can provide golf players with a golf club shaft and golf club that are lightweight, have high strength, and provide a clear feel when hitting the ball. [Explanation of symbols]

[0052] 1 Composite material 10 First member 11 Fiber-reinforced plastic layer 20 Second member 100 Golf Club Shafts 110 Shaft body

Claims

1. 1. A golf club shaft having a longitudinally extending shaft body, the shaft body includes a first member having a fiber-reinforced plastic, and a second member having a rubber material formed on the first member in direct contact with the first member in at least a partial region thereof, The first member and the second member are made of an integrated composite material, The shaft body has, in order from the base end side to the tip end side in the longitudinal direction, a first region in which the shaft outer diameter decreases relatively gradually, a second region in which the shaft outer diameter decreases relatively sharply, and a third region in which the relative amount of change in the shaft outer diameter is smallest.

2. 2. The golf club shaft according to claim 1, wherein a portion of the first member and the second member are in direct contact with each other, and no adhesive member is interposed between the first member and the second member.

3. 3. The golf club shaft according to claim 1, wherein the first member and the second member are in the form of sheets, and the composite material has a laminate structure.

4. 4. The golf club shaft according to claim 1, wherein the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, butyl rubber, ethylene propylene diene rubber, hydrogenated nitrile rubber, and silicone rubber.

5. 5. The golf club shaft according to claim 1, wherein the rubber material is at least one selected from the group consisting of nitrile rubber, fluororubber, and butyl rubber.

6. 6. The golf club shaft according to claim 1, wherein the fiber reinforced plastic is a carbon fiber reinforced plastic.

7. 7. A golf club shaft according to claim 1, wherein the first member is a multi-layer structure having a first fiber-reinforced plastic forming a first layer having a fiber orientation angle in a first direction, and a second fiber-reinforced plastic forming a second layer having a fiber orientation angle in a second direction different from the first direction.

8. 8. The golf club shaft according to claim 1, wherein the outer surface of the composite material is the first member.

9. A golf club comprising a club head and a grip attached to the golf club shaft according to any one of claims 1 to 8.

10. providing a first precursor, which is an uncured or semi-cured material in which fibers are impregnated with a resin; a step of directly laminating a second precursor having unvulcanized rubber on at least a partial area of ​​the prepared first precursor to obtain a laminate of the first precursor and the second precursor; a step of winding the obtained laminate around an outer peripheral surface of a mandrel; a step of heat-treating the laminate wound on the outer peripheral surface of the mandrel to thermally cure the resin of the first precursor to obtain a first member having a fiber-reinforced plastic and vulcanizing the unvulcanized rubber of the second precursor to obtain a second member having a rubber material, and integrating the first member and the second member to obtain a wound composite material; withdrawing the mandrel from the wound composite material; A method for manufacturing a golf club shaft having the following structure:

11. 11. The method for manufacturing a golf club shaft according to claim 10, wherein the second precursor having unvulcanized rubber mixed with a vulcanizing agent is laminated directly onto the prepared first precursor without using an adhesive member.

Images