Golf club head

Abstract

The present invention suppresses performance variations in high initial velocity area, carry, durability, hitting feel, and the like.　The present invention is formed from a first layer 36 at which a face part 14 is supported by a head body 12A, a second layer 38 that is provided to a surface of the first layer 36 that is on the reverse side from a hollow part 22 of the head body 12A, and a third layer 40 that is provided to a surface of the second layer 38 that is on the reverse side from the first layer 36. The second layer 38 is formed from an adhesive layer that comprises an adhesive 44 and a mesh body 42 that is a mesh of woven or knitted fibers and is impregnated with the adhesive 44.

Description

Golf club head

[0001] The present invention relates to a golf club head.

[0002] 2. Description of the Related Art Various golf club heads have been proposed, each having a face portion formed by laminating a plurality of layers made of different materials and bonding them together with an adhesive layer (see, for example, Patent Document 1).

[0003] JP 2022-063703 A Patent No. 6446843 A

[0004] However, in the above-mentioned conventional technology, the thickness of the adhesive layer is prone to variation, which leads to variation in the performance of the golf club head, such as the high initial velocity area (sweet spot), flight distance, durability, and feel, and some kind of improvement is required. The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a golf club head that is advantageous in suppressing variation in performance, such as the high initial velocity area (sweet spot), flight distance, durability, and feel.

[0005] In order to achieve the above object, one embodiment of the present invention is a golf club head having a hollow structure in which at least a portion of the face portion comprises a first layer supported by the head body, a second layer provided on the surface of the first layer located opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer located opposite the first layer, and the surface of the third layer located opposite the second layer forms the face surface, and is characterized in that the second layer is composed of an adhesive layer comprising an adhesive and a mesh body in which fibers are woven or knitted in a mesh pattern and are impregnated with the adhesive. Furthermore, one embodiment of the present invention is a golf club head having a hollow structure in which at least a portion of a face portion comprises a first layer supported by a head body, a second layer provided on the surface of the first layer located opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer located opposite the first layer, and the surface of the third layer located opposite the second layer forms the face surface, wherein the second layer is formed as an adhesive layer made of adhesive, and a plurality of cylindrical first convex portions are formed on the back surface of the third layer located opposite the face surface, protruding through the adhesive layer toward the second layer and abutting the surface of the first layer facing the back surface of the third layer, the height of the first convex portions being 0.2 mm or more and 0.5 mm or less, and the diameter of the first convex portions being 0.5 mm or more and 2.0 mm or less. Furthermore, one embodiment of the present invention is a golf club head having a hollow structure in which at least a portion of a face portion comprises a first layer supported by a head body, a second layer provided on the surface of the first layer opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer opposite the first layer, and the surface of the third layer opposite the second layer forms the face surface, wherein the second layer is formed as an adhesive layer made of adhesive, and a plurality of cylindrical second convex portions are formed on the surface of the first layer, protruding through the adhesive layer toward the second layer and abutting the back surface of the third layer opposite the surface of the first layer, the height of the second convex portions being 0.2 mm or more and 0.5 mm or less, and the diameter of the second convex portions being 0.5 mm or more and 2.0 mm or less.In one embodiment of the present invention, there is provided a golf club head having a hollow structure, at least a portion of a face portion comprising: a first layer supported by a head body, a second layer provided on a surface of the first layer opposite a hollow portion of the head body, and a third layer provided on a surface of the second layer opposite the first layer, the surface of the third layer opposite the second layer constituting a face surface, wherein the second layer is formed as an adhesive layer comprising an elastic adhesive and a plurality of rigid spheres having a uniform diameter of 0.1 mm to 0.5 mm and mixed into the elastic adhesive. In another embodiment of the present invention, there is provided a golf club head having a hollow structure, at least a portion of a face portion comprising: a first layer supported by a head body, a second layer provided on a surface of the first layer opposite a hollow portion of the head body, and a third layer provided on a surface of the second layer opposite the first layer, the surface of the third layer opposite the second layer constituting a face surface, wherein the second layer is formed as an adhesive layer comprising a film-like sheet adhesive.

[0006] According to one embodiment of the present invention, the mesh body is impregnated with adhesive, which allows the adhesive to be evenly distributed throughout the entire mesh body at the same thickness as the mesh body, thereby making the adhesive thickness in the second layer uniform and reducing thickness variations in the second layer, which is advantageous for reducing variations in the high initial velocity area, flight distance, and durability of the golf club head. Also, according to one embodiment of the present invention, the provision of multiple first convex portions allows the adhesive to be evenly distributed between the first and third layers, which allows the adhesive thickness in the second layer to be uniform and reducing thickness variations in the second layer, which is advantageous for reducing variations in the high initial velocity area, flight distance, and durability of the golf club head. Also, according to one embodiment of the present invention, the provision of multiple second convex portions allows the adhesive to be evenly distributed throughout the entire area between the first and third layers, which allows the adhesive thickness in the second layer to be uniform and reducing thickness variations in the second layer, which is advantageous for reducing variations in the high initial velocity area, flight distance, and durability of the golf club head. Furthermore, according to one embodiment of the present invention, since a plurality of spheres are mixed into the adhesive, the adhesive is evenly distributed throughout the entire area between the first and third layers, thereby making the thickness of the adhesive in the second layer uniform and reducing variations in the thickness of the second layer, which is advantageous in reducing variations in the high initial velocity area, flight distance, and durability of the golf club head. Furthermore, according to one embodiment of the present invention, the sheet adhesive is evenly distributed between the first and third layers, thereby making the thickness of the second layer uniform and reducing variations in the thickness of the second layer, which is advantageous in reducing variations in the high initial velocity area, flight distance, and durability of the golf club head.

[0007] 1 is a front view of a golf club head according to a first embodiment, as seen from the front of the face surface. FIG. 1 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 2 is an enlarged cross-sectional view of the face portion. FIG. 3 is a plan view of a mesh body made of a plain weave fabric in which rectangular meshes are formed. FIG. 4 is a plan view of a mesh body made of tulle, a knitted fabric in which hexagonal (polygonal) meshes are formed. FIG. 5 is a front view showing the mesh body of FIG. 4 placed on the surface of a first layer. FIG. 6 is a front view showing the mesh body of FIG. 6 placed on the surface of a first layer. FIG. 7 is a first explanatory view showing a method of defining the center point Pc of the face surface. FIG. 8 is a second explanatory view showing a method of defining the center point Pc of the face surface. FIG. 9 is a third explanatory view showing a method of defining the center point Pc of the face surface. FIG. 10 is a fourth explanatory view showing a method of defining the center point Pc of the face surface. FIG. 11 is a cross-sectional view of a golf club head showing the relationship between the center of gravity G0 of the golf club head and the center of gravity FG on the face surface. FIG. 12 is a front view of a golf club head illustrating the definition of the contour line I of the face surface. FIG. 1 is a front view of a golf club head illustrating the definition of the center point Pc of the face surface. FIG. 2 is an enlarged cross-sectional view of a face portion of a golf club head according to a second embodiment. FIG. 3 is an enlarged cross-sectional view of a face portion of a golf club head according to a third embodiment. FIG. 4 is an enlarged cross-sectional view of a face portion of a golf club head according to a fourth embodiment. FIG. 5 is an enlarged cross-sectional view of a face portion of a golf club head according to a fifth embodiment. FIG. 6 is a diagram illustrating evaluation results of an experimental example under condition 1. FIG. 7 is a diagram illustrating evaluation results of an experimental example under condition 2. FIG. 8 is a diagram illustrating evaluation results of an experimental example under condition 3. FIG. 9 is a diagram illustrating evaluation results of an experimental example under condition 4. FIG. 10 is an explanatory diagram of a method of manufacturing a golf club head using a mold and a press.

[0008] First Embodiment First, a first embodiment will be described. As shown in FIGS. 1 and 2 , in this embodiment, a golf club head 10A is a hollow wood-type golf club head (driver). A head body 12A of the golf club head 10A, excluding a face portion 14 (described later), is made of a metal material or a fiber-reinforced plastic material (FRP), or a combination of a metal material and a fiber-reinforced plastic material. Examples of the metal material include one or more of stainless steel, maraging steel, pure titanium, a titanium alloy, and an aluminum alloy. Examples of such titanium alloys include 6-4Ti and 8-1-1Ti. Examples of the fiber-reinforced plastic material include a carbon fiber-reinforced plastic material (CFRP). The golf club head 10A includes a face portion 14, a crown portion 16, a sole portion 18, and a side portion 20. The golf club head 10A has a hollow structure in which the interior surrounded by the face portion 14, crown portion 16, sole portion 18, and side portion 20 is a hollow portion 22 (see FIG. 2). The face portion 14 has a vertical height and extends horizontally.

[0009] The crown portion 16 has a thickness smaller than that of the face portion 14 and extends rearward from the upper portion of the face portion 14. The surface exposed to the outside of the face portion 14 is a face surface 1402 that strikes the ball. A hosel 28 that connects to a shaft S is provided on the crown portion 16 at a position on the face surface 1402 side and closer to the heel 26, and the golf club 100 is configured by connecting the shaft S to the hosel 28. The sole portion 18 extends rearward from the lower portion of the face portion 14. The side portion 20 extends between the crown portion 16 and the sole portion 18, passing through the back of the face, between the toe 24 side edge and the heel 26 side edge of the face portion 14.

[0010] As shown in FIG. 2 , the golf club head 10A includes a hollow head main body 12A, a plate-shaped first face member 30, and a plate-shaped second face member 32. The face portion 14 of the golf club head 10A is composed of a face-forming plate 34 of the head main body 12A and the first and second face members 30, 32. In other words, the face portion 14 of the golf club head 10A includes a first layer 36 supported by the head main body 12A, a second layer 38 provided on the surface of the first layer 36 opposite the hollow portion 22 of the head main body 12A, and a third layer 40 provided on the surface of the second layer 38 opposite the first layer 36, and the surface of the third layer 40 opposite the second layer 38 forms a face surface 1402. The first layer 36 is composed of the face-forming plate 34. The second layer 38 is made up of the first face member 30 and is attached to the surface of the face portion plate 34 opposite the hollow portion 22. The third layer 40 is made up of the second face member 32 and is attached to the surface of the first face member 30 opposite the face portion plate 34. In this embodiment, the head main body 12A and the face portion plate 34 are made of the same material, for example, 8-1-1Ti (cast material).

[0011] The hardness of the first layer 36 is Shore D75 or more and Vickers hardness HV520 or less, and the bending rigidity of the first layer 36 is 8000 N mm ２ 230,000N・mm or more ２ The thickness of the first layer 36 is 1.0 mm or more and 6.0 mm or less. Shore hardness (A or D) is measured using a test procedure conforming to ISO 7619-1 or ASTM D2240. Vickers hardness HV is measured using a test procedure conforming to ISO 6507 / ASTM E384. Having the hardness, flexural rigidity, and thickness of the first layer 36 within the above ranges is advantageous in suppressing variations in the high initial velocity area, flight distance, and durability described below, while being outside the above ranges reduces these effects. Examples of materials that can be used for the first layer 36 include titanium alloy 6Al-4V and carbon fiber reinforced plastic (CFRP).

[0012] The third layer 40 has a hardness of Shore D75 or more and a Vickers hardness of HV520 or less, and a bending rigidity of 100 N mm ２ More than 3000N・mm ２ The hardness, bending rigidity, and thickness of the third layer 40 are 0.2 mm or more and 2.0 mm or less. If the hardness, bending rigidity, and thickness of the third layer 40 are within the above ranges, it is advantageous in suppressing variations in the high initial velocity area, flight distance, and durability, which will be described later, while if they are outside the above ranges, the above effects are reduced. Metal materials, fiber-reinforced resins, and synthetic resins can be used as materials for the third layer 40. Examples of the material, thickness, and bending rigidity of the third layer 40 are as follows: Aluminum 1.5 mm 2700 N·mm ２ CFRP 0.75mm 2148N・mm ２ PC 2.0mm 1800N・mm ２ SUS304 0.5mm 2010N・mm ２ SUS304 0.2mm 137N・mm ２ Pure titanium 0.4mm 549N・mm ２

[0013] Specifically, the second layer 38 (first face member 30) is described below. As shown in FIG. 3 , the second layer 38 is composed of a mesh body 42 in which fibers 48 are woven or knitted into a mesh shape, and an adhesive 44 that has been impregnated into the mesh body 42 and hardened. In other words, the second layer 38 is composed of the mesh body 42 and an adhesive layer including the adhesive 44 that has been impregnated into the mesh body 42. In this embodiment, the second layer 38 is composed of an adhesive layer including the adhesive 44 and the mesh body 42. The mesh body 42 abuts against the back surface of the third layer 40, which is located opposite the face surface 1402, and the first layer 36. In this embodiment, a liquid thermosetting adhesive 44 is used as the adhesive 44. However, any type of adhesive 44 may be used as long as it can be impregnated into the mesh body 42 and harden to form the second layer 38. While the type of adhesive 44 is not limited, an elastic adhesive is preferred. Alternatively, a thermoplastic hot melt adhesive or the like may be used. As shown in Figure 4, the mesh body 42 in which fibers 48 are woven into a mesh shape may be, for example, a plain weave fabric in which one warp thread crosses one weft thread, such as glass cloth 43, which is a glass fiber fabric. However, the mesh body 42 may also be made of various conventionally known fabrics other than plain weave. Furthermore, the thickness of the mesh body 42 is locally greater at the intersections of the warp threads and weft threads than at other locations. In this example, the mesh 50 of the mesh body 42 is rectangular.

[0014] As shown in FIG. 5 , an example of a mesh body 42 formed by weaving fibers 48 into a mesh shape is tulle 46, a knitted fabric in which polygonal (hexagonal in this embodiment) meshes 50 are formed by weaving fibers 48. Knitted fabrics such as tulle 46 use two warp threads, but no weft threads, and combine them to form mesh 50. Therefore, unlike woven fabrics, the thickness of the mesh body 42 does not increase locally at the intersections of the warp and weft threads, and the thickness of the mesh body 42 is generally uniform. Therefore, constructing the mesh body 42 from a knitted fabric such as tulle 46 is more advantageous than constructing the mesh body 42 from a woven fabric such as glass cloth 43 in terms of suppressing thickness variations in the adhesive 44 constituting the second layer 38 and achieving a uniform thickness for the second layer 38. For example, nylon tulle has a thickness of 0.2 to 0.4 mm. A net with polygonal mesh (hexagonal stitches) is called "tulle," and those knitted with one set of ground yarn (one piece) are called "single-ply tulle," and those knitted with two sets of ground yarn are called "two-ply tulle." A net made up of hexagonal meshes called "hexagonal mesh" is common.

[0015] Here, the thickness T of the mesh body 42 is 0.1 mm or more and 1.0 mm or less. When the thickness T of the mesh body 42 is within the above range, the thickness of the second layer 38 can be ensured within an appropriate range, which is advantageous for suppressing variations in the high initial velocity area, flight distance, and durability described below. When the thickness T of the mesh body 42 is below or above the above range, the thickness of the second layer 38 cannot be ensured within the appropriate range, and the above-mentioned effects are reduced. Furthermore, the thickness D of the fiber 48 is 0.1 mm or more and 1.0 mm or less. When the thickness D of the fiber 48 is within the above range, the amount of adhesive 44 impregnated into the mesh body 42 can be ensured within an appropriate range, which is advantageous for achieving the above-mentioned effects. When the thickness D of the fiber 48 is below or above the above range, the amount of adhesive 44 impregnated into the mesh body 42 cannot ... the appropriate range, and the above-mentioned effects are reduced. Furthermore, the opening dimension S of the mesh 50 of the mesh body 42 is 0.3 mm or more and 3.0 mm or less. Regarding the opening dimension S, when the mesh 50 is rectangular as shown in FIG. 4 , the opening dimension S is the distance between two opposing fibers 48 that make up the mesh 50. When the mesh 50 is polygonal as shown in FIG. 5 , the opening dimension S is the distance between two opposing fibers 48 that make up the mesh 50, or the distance between two opposing vertices of the opposing polygons that make up the mesh 50. When the opening dimension S is within the above range, the amount of adhesive 44 impregnated into the mesh body 42, the uniform thickness, and the amount of voids can be ensured within appropriate ranges, which is advantageous for achieving the above-mentioned effects. When the opening dimension S is below or above the above range, the amount of adhesive 44 impregnated into the mesh body 42, the uniform thickness, and the amount of voids cannot be ensured within appropriate ranges, and the above-mentioned effects are reduced.

[0016] The fibers 48 that make up the mesh body 42 are made of synthetic resin, carbon resin, glass, or metal. Examples of synthetic resins include nylon, polyester, polyethylene, polypropylene, and PEEK. Examples of metals include aluminum, titanium, stainless steel, brass, nickel, copper, molybdenum, and tungsten. When the fibers 48 are made of synthetic resin or carbon resin, the surfaces of the fibers 48 may be coated with melamine resin to ensure the rigidity of the mesh body 42, maintain the shape of the mesh 50 of the mesh body 42, and ensure the opening dimension S.

[0017] Next, the adhesive 44 will be described. In this embodiment, the adhesive 44 is a thermosetting adhesive that is liquid and hardens when heated. Alternatively, a thermoplastic hot melt may be used. The hardness of the hardened adhesive 44 at 25°C is Shore A 40 or more and 95 or less. The tan δ of the hardened adhesive 44 at 25°C to 80°C is 0.05 or more and 0.4 or less. If the hardness and tan δ of the hardened adhesive 44 are within the above ranges, this is advantageous in suppressing variations in the high initial velocity area, flight distance, and durability, as described below. If the hardness and tan δ of the hardened adhesive 44 are outside the above ranges, the above effects are reduced. For example, the following adhesives can be used as the adhesive 44. For heat curing, there are: ・Elastic epoxy resin elastic adhesive Bond MOS8 (product name) from Konishi Co., Ltd. ・Epoxy modified silicone elastic adhesive Cemedine EP001K (product name) from Cemedine Co., Ltd. ・Two-component room temperature curing strong adhesive ThreeBond 3953 (product name) from ThreeBond Co., Ltd. ・Sekisui Bond #55 (product name) from Sekisui Fuller Co., Ltd. For thermoplastic, there are hot melts: ・FIXELON (product name) from Aicello Co., Ltd. ・Metaseal (product name) from Fujimori Kogyo Co., Ltd.

[0018] In the case of thermal curing, the adhesive 44 may contain a silyl group-terminated polymer and an organometallic catalyst necessary for the silyl groups to undergo a condensation reaction to form a crosslinked structure. The silyl group-terminated polymer may have an end group represented by Structural Formula 1, and the number of such end groups may be an average of 1.5 to 3 per polymer molecule.

[0019] (Structural formula 1)

[0020] (where n = 2 or 3, n + m = 3, R: CH ３ -, C ２ H ５ -, C ３ H ９ The adhesive 44 may also contain an amine catalyst necessary for forming a crosslinked structure by addition reaction between epoxy resins together with the silyl group-terminated polymer.

[0021] 1, the fill rate of the adhesive 44 filling the mesh 50 of the mesh body 42 in the impact area IA of the face portion 14 is 95% or more and 100% or less. If the fill rate is within this range, the second layer 38 can be reliably formed over the entire area, which is advantageous in suppressing variations in the high initial velocity area, flight distance, and durability, as described below. If the fill rate is below this range, the above effects will be reduced.

[0022] Furthermore, in the impact area IA of the face portion 14, the thickness variation of the second layer 38 is within ±0.15 mm, preferably within ±0.1 mm. A thickness variation of the second layer 38 within ±0.15 mm is advantageous in suppressing variations in the high initial velocity area, flight distance, and durability described below. However, if the thickness variation of the second layer 38 exceeds this range, these effects are reduced. A thickness variation of the second layer 38 within ±0.1 mm is more advantageous in suppressing variations in the high initial velocity area, flight distance, and durability described below. As shown in FIG. 1 , according to the R&A rules, the impact area IA of the face portion 14 is a strip-shaped portion having a width of 1.68 inches (42.67 mm) that passes through the center point Pc of the face surface 1402. The center point Pc of the face surface 1402 is defined as follows:

[0023] (Definition of Center Point Pc of Face Surface 1402) The following describes a method for defining the center point Pc of the face surface 1402. The center point Pc of the face surface 1402 is the geometric center of the face surface 1402, and various conventionally known methods can be used to define the center point Pc, including the first and second definition methods exemplified below.

[0024] [A] First method for defining the center point Pc of the face surface 1402: This is a method for defining the center point Pc when the boundary between the face surface 1402 and other parts of the golf club head 10A is clear, in other words, when the periphery of the face surface 1402 is identified by a ridge line. In this case, the face surface 1402 is clearly defined. Figures 8 to 11 are explanatory diagrams showing methods for defining the center point Pc of the face surface 1402.

[0025] (1) First, as shown in Figure 8, the golf club head 10A is placed on a horizontal plane HP so that the lie angle and face angle are set to specified values. The state of the golf club head 10A at this time is defined as the reference state. The set values ​​of the lie angle and face angle are, for example, values ​​listed in the product catalog.

[0026] (2) Next, a provisional center point c0 is determined in the direction connecting the crown portion 16 and the sole portion 18. That is, as shown in Fig. 8, a perpendicular line f0 is drawn that intersects with the approximate center point of a line (hereinafter referred to as the horizontal line) that is parallel to the horizontal plane HP connecting the toe 24 and the heel 26. The provisional center point c0 is the midpoint between point a0 where this perpendicular line f0 intersects with the upper edge of the face surface 1402 and point b0 where the perpendicular line f0 intersects with the lower edge of the face surface 1402.

[0027] (3) Next, draw a horizontal line g0 that passes through the provisional center point c0 as shown in Fig. 9. (4) Next, as shown in Fig. 10, the midpoint between point d0 where the horizontal line g0 intersects with the edge of the face surface 1402 on the toe 24 side and point e0 where the horizontal line g0 intersects with the edge of the face surface 1402 on the heel 26 side is set as the provisional center point c1.

[0028] (5) Next, as shown in FIG. 11 , a perpendicular line f1 passing through the provisional center point c1 is drawn, and the midpoint between point a1 where this perpendicular line f1 intersects with the upper edge of the face surface 1402 and point b1 where the perpendicular line f1 intersects with the lower edge of the face surface 1402 is defined as provisional center point c2. Here, if provisional center points c1 and c2 coincide, this point is defined as the center point Pc of the face surface 1402. If provisional center points c1 and c2 do not coincide, steps (2) to (5) are repeated. Note that, because the face surface 1402 is curved, the length of the horizontal line g0 and the lengths of the perpendicular lines f0 and f1 used when determining the midpoint of the horizontal line g0 and the midpoint of the perpendicular lines f0 and f1 are lengths along the curved surface of the face surface 1402. The face center line CL is defined as a straight line passing through the center point Pc and extending in a direction perpendicular to the toe-heel direction.

[0029] [B] Second method for defining the center point Pc of the face surface 1402: Next, we will explain the definition of the center point Pc when the periphery of the face surface 1402 and other parts of the golf club head 10A are connected by a curved surface and the face surface 1402 cannot be clearly defined.

[0030] 12, the golf club head 10A is hollow, and the symbol G0 indicates the center of gravity of the golf club head 10A, and the symbol Lp is a straight line connecting the center of gravity G0 and the center of gravity FG on the face surface 1402. In other words, the straight line Lp is a perpendicular line to the face surface 1402 that passes through the center of gravity G0. In other words, the point where the center of gravity G0 of the golf club head 10A is projected onto the face surface 1402 is the center of gravity FG on the face surface 1402. Here, as shown in FIG. 13, consider a number of planes H1, H2, H3, ..., Hn that include the straight line Lp connecting the center of gravity G0 and the center of gravity FG on the face surface 1402.

[0031] As shown in FIG. 14 , the radius of curvature r0 of the outer surface of the golf club head 10A is measured in a cross section obtained by cutting the golf club head 10A along each plane H1, H2, H3, ..., Hn. When measuring the radius of curvature r0, it is assumed that there are no face lines, punch marks, or the like on the face surface 1402. The radius of curvature r0 is continuously measured outward (upward and downward in FIG. 14 ) from the center point Pc of the face surface 1402. Then, the portion where the radius of curvature r0 first becomes equal to or smaller than a predetermined value in the measurement is defined as a contour line I representing the periphery of the face surface 1402. The predetermined value is, for example, 200 mm. The area surrounded by the contour line I determined based on the multiple planes H1, H2, H3, ..., Hn is defined as the face surface 1402, as shown in FIGS. 13 and 14 .

[0032] Next, as shown in FIG. 15 , the golf club head 10A is placed on a horizontal ground surface (horizontal plane HP) so that the lie angle and face angle are set to specified values. A line LT passes through a toe-side point PT of the face surface 1402 and extends vertically. A line LH passes through a heel-side point PH of the face surface 1402 and extends vertically. A line LC is parallel to the lines LT and LH. The distance between the lines LC and LT is equal to the distance between the lines LC and LH. The symbol Pu indicates an upper point of the face surface 1402, and the symbol Pd indicates a lower point of the face surface 1402. The upper point Pu and the lower point Pd are both intersections of the line LC and the contour line I. The center point Pc is defined as the midpoint of the line segment connecting the upper point Pu and the lower point Pd.

[0033] (Manufacturing Method of Golf Club Head 10A: First Embodiment) Next, a manufacturing method for the golf club head 10A of this embodiment will be described. The method for using a thermosetting liquid adhesive is as follows. First, the adhesive 44 that forms the second layer 38 is applied to the surface of the face plate 34 that forms the first layer 36 of the head body 12A. The adhesive 44 may also be applied to the third layer 40 (e.g., 0.75 mm CFRP). Typically, to ensure adhesive strength, it is desirable to subject the surface of the face plate 34 where the adhesive is to be applied and the third layer 40 to a blasting treatment. Next, as shown in FIGS. 6 and 7 , a mesh 42 formed to have a contour that matches the contour of the first layer 36 is placed on the adhesive 44. This allows the mesh 42 to be impregnated with the adhesive 44. Alternatively, the mesh 42 may be cut to fit the face contour after the adhesive has hardened, with the mesh 42 being slightly larger than the face contour. Next, as shown in FIG. 24 , the head main body 12A is placed in a mold 100 with the second face member 32, which constitutes the third layer 40, placed on the mesh body 42. A resin plate 102, such as silicone, is placed on the second face member 32. A press 104 is used to apply uniform pressure to the second face member 32 from above, maintaining a constant pressure using a torque wrench or similar tool, and the second face member 32 is then fixed in place using a jig or similar tool. The position of the mold 100 is adjusted so that the second layer 38 has a predetermined thickness. The adhesive is also ensured to overflow from the third layer 40, covering the entire face surface 1402. This ensures that the mesh member 42 and the adhesive 44 impregnated therein are pressurized between the face plate 34 and the second face member 32, ensuring that the adhesive 44 is evenly impregnated throughout the entire area of ​​the pressurized mesh member 42. Any excess adhesive 44 spills out from the outer edge of the mesh member 42. The excess adhesive 44 is then removed from the head main body 12A. The first face member 30, second face member 32, head main body 12A, and fixing jig are then placed in a heating oven together with the mold 100 and heated for a predetermined time, for example, about one hour at 30°C to 120°C, to thermally cure the adhesive 44. Once thermal curing is complete, the mold 100 and fixing jig are opened and the completed golf club head 10A is removed. Another possible manufacturing method is autoclave manufacturing.To apply atmospheric pressure from above to the head body 12A, which consists of the first layer (36, 34), the second layer (38, 30), and the third layer (40, 32), a mold is sealed with an airtight plastic film, and air trapped between the sealant and the mold is removed (bagging). After that, to prevent voids from forming inside the second layer (38, 30) if air remains during adhesive curing, a vacuum is drawn to remove any remaining air to ensure uniform thickness. The mold 100 and fixtures are also placed in a pressure vessel called an autoclave, where they are pressurized, heated, and cured. As shown in FIG. 2 , the outer surface (face surface 1402) of the third layer 40 is elevated relative to the outer surface of the first layer 36 by the thickness of the second layer 38 and the third layer 40, forming an annular step between the outer surface of the first layer 36 and the outer peripheral surfaces of the second layer 38 and the third layer 40. To eliminate this step, for example, a ring-shaped synthetic resin 41 (e.g., putty) having the same thickness as the step is bonded between the outer peripheral surfaces of the second layer 38 and the third layer 40 and the outer surface of the first layer 36. The outer peripheral portion of the third layer 40 and the synthetic resin 41 are then polished to form a smooth curved surface connecting the outer surface of the first layer 36 and the outer surface (face surface 1402) of the third layer 40. Then, a ring-shaped paint (not shown) is applied to the outer peripheral portion of the outer surface (face surface 1402) of the third layer 40, the curved surface of the synthetic resin 41, and the outer surface of the first layer 36. This painting process conceals the step and improves the appearance of the golf club head 10A. In this manner, a golf club head 10A having a face portion 14 including the first layer 36, the second layer 38, and the third layer 40 is manufactured. Alternatively, the annular step can be eliminated by increasing the height of the outer periphery of the face surface 1402 by the thickness of the second layer 38 and the third layer 40 and decreasing the inner surface.

[0034] As described above, according to this embodiment, the face portion 14 is composed of a first layer 36 supported by the head main body 12A, a second layer 38 provided on the surface of the first layer 36 opposite the hollow portion 22 of the head main body 12A, and a third layer 40 provided on the surface of the second layer 38 opposite the first layer 36. The second layer 38 is composed of an adhesive layer including an adhesive 44 and a mesh body 42 in which fibers are woven or knitted into a mesh shape and impregnated with the adhesive 44. Therefore, by impregnating the mesh body 42 with the adhesive 44, the adhesive 44 is evenly distributed throughout the entire area of ​​the mesh body 42 to the same thickness as the mesh body 42, thereby making the thickness of the adhesive 44 in the second layer 38 uniform and suppressing variations in the thickness of the second layer 38. This is advantageous in suppressing variations in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10A.

[0035] Second Embodiment Next, a golf club head 10B according to a second embodiment will be described with reference to FIG. 16 . In the following description, the same components and parts as those of the first embodiment are denoted by the same reference numerals, and their description will be omitted. The following description will focus on the differences. As shown in FIG. 16 , the second embodiment uses first protrusions 52 instead of the mesh body 42 of the first embodiment. That is, the face plate 34 constituting the first layer 36 and the second face member 32 constituting the third layer 40 are the same as those of the first embodiment. The second layer 38 is formed of a hardened adhesive 44, and a plurality of cylindrical first protrusions 52 protruding toward the second layer 38 are formed over substantially the entire back surface of the third layer 40, which is located opposite the face surface 1402. In other words, the second layer 38 is formed of an adhesive layer made of adhesive 44, and a plurality of cylindrical first protrusions 52 are formed on the back surface of the third layer 40 located opposite the face surface 1402, protruding through the adhesive layer toward the second layer 38 and abutting on the surface of the first layer 36 facing the back surface of the third layer 40. More specifically, the first protrusions 52 have a uniform height h1 that penetrates the second layer 38 and abuts on the first layer 36. The height h1 of the first protrusions 52 is 0.2 mm or more and 0.5 mm or less, and the diameter w1 of the first protrusions 52 is 0.5 mm or more and 2.0 mm or less. When the height h1 and diameter w1 of the first convex portions 52 are within the above ranges, the adhesive 44 flows between the first convex portions 52, and the thickness (height) of the first convex portions 52 makes it easier to ensure the thickness of the adhesive 44. This reduces variation in the thickness of the second layer 38, which is advantageous for reducing variation in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10B. If the height h1 and diameter w1 of the first convex portions 52 are below or above the above ranges, the adhesive 44 does not flow easily between the first convex portions 52, making it harder for the thickness of the first convex portions 52 to ensure the thickness of the adhesive 44. This makes it easier for variation in the thickness of the second layer 38 to occur, which reduces the above-mentioned effects. In particular, if the height h1 and diameter w1 of the first convex portions 52 are above the above ranges, the rigidity of the face surface 1402 becomes too high, resulting in reduced resilience.

[0036] The golf club head 10B of the second embodiment is manufactured as follows. The method using a thermosetting liquid adhesive is as follows. First, the adhesive 44 constituting the second layer 38 is applied to the surface of the face plate 34 constituting the first layer 36 of the head body 12B. The adhesive 44 may also be applied to the third layer 40 (e.g., 0.75 mm CFRP). Typically, to ensure adhesive strength, it is desirable to blast the surface of the face plate 34 where the adhesive is applied and the third layer 40. Next, as shown in FIG. 24 , the head body 12B is placed in a mold 100 with the second face member 32 constituting the third layer 40 placed on the first layer 36 via the adhesive 44. A resin plate 102 such as silicone is placed on the second face member 32, and a press 104 is used from above to apply a uniform force to the second face member 32, maintaining a constant pressure with a torque wrench or the like, and the second face member 32 is fixed in place with a jig or the like. The mold 100 is then positioned so that the second layer 38 has a predetermined thickness. In addition, the adhesive is always made to overflow from the third layer 40 so that the adhesive covers the entire face surface 1402. As a result, the adhesive 44 located between the first layer 36 and the third layer 40 flows between the multiple first protrusions 52 and is evenly filled between the first layer 36 and the third layer 40, and excess adhesive 44 overflows from between the first layer 36 and the third layer 40. The overflowed excess adhesive 44 is removed from the head main body 12B. As a result, the adhesive 44 located between the first layer 36 and the third layer 40 flows between the multiple first protrusions 52 and is evenly filled between the first layer 36 and the third layer 40, and excess adhesive 44 overflows from between the first layer 36 and the third layer 40. The overflowed excess adhesive 44 is removed from the head main body 12B. Then, the first face member 30, the second face member 32, the head main body 12A, the fixing jig, etc. are placed in a heating oven together with the mold 100 and heated for a predetermined time, for example, about one hour at 30°C to 120°C, to thermally cure the adhesive 44. Once thermal curing is complete, the mold 100 and the fixing jig are opened and the completed golf club head 10A is removed. As mentioned above, an autoclave manufacturing method is also possible.

[0037] According to the second embodiment, the adhesive 44 is evenly distributed over the entire area between the first layer 36 and the third layer 40, which makes the thickness of the adhesive 44 in the second layer 38 uniform and reduces variations in the thickness of the second layer 38. This is advantageous in reducing variations in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10B.

[0038] Third Embodiment Next, a golf club head 10C according to a third embodiment will be described with reference to FIG. 17 . As shown in FIG. 17 , the third embodiment uses second protrusions 54 instead of the mesh body 42 of the first embodiment. That is, the face plate 34 constituting the first layer 36 and the second face member 32 constituting the third layer 40 are the same as those of the first embodiment. The second layer 38 is formed of a hardened adhesive 44, and a plurality of second protrusions 54 protruding toward the second layer 38 are formed over almost the entire surface of the first layer 36. In other words, the second layer 38 is formed as an adhesive layer made of the adhesive 44, and a plurality of cylindrical second protrusions 54 are formed on the surface of the first layer 36, passing through the adhesive layer and protruding toward the second layer 38 to abut the back surface of the third layer 40 opposite the surface of the first layer 36. More specifically, the second convex portions 54 have a uniform height h2 that penetrates the second layer 38 and abuts against the back surface of the third layer 40 located opposite the face surface 1402. The height h2 of the second convex portions 54 is 0.2 mm or more and 0.5 mm or less, and the diameter w2 of the second convex portions 54 is 0.5 mm or more and 2.0 mm or less. When the height h2 and diameter w2 of the second convex portions 54 are within the above ranges, the adhesive 44 flows between the second convex portions 54, and the thickness (height) of the second convex portions 54 makes it easier to ensure the thickness of the adhesive 44. This reduces variation in the thickness of the second layer 38, which is advantageous for reducing variation in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10B. If the height h2 or diameter w2 of the second convex portions 54 is below or above the above range, the adhesive 44 will have difficulty flowing between the second convex portions 54, and it will be difficult to ensure the thickness of the adhesive 44 with the thickness (height) of the second convex portions 54, which will result in variations in the thickness of the second layer 38 and a decrease in the above-mentioned effect. In particular, if the height h2 or diameter w2 of the second convex portions 54 is above the above range, the rigidity of the face surface 1402 will be too high, resulting in a decrease in resilience.

[0039] The manufacturing method of the golf club head 10C of the third embodiment is as follows. The method using a thermosetting liquid adhesive is as follows. First, the adhesive 44 constituting the second layer 38 is applied to the surface of the face plate 34 constituting the first layer 36 of the head main body 12C. The adhesive 44 may also be applied to the third layer 40 (e.g., 0.75 mm CFRP). Typically, to ensure adhesive strength, it is desirable to blast the surface of the face plate 34 where the adhesive is applied and the third layer 40. Next, as shown in FIG. 24 , the head main body 12C is placed in a mold 100 with the second face member 32 constituting the third layer 40 placed on the first layer 36 via the adhesive 44. A resin plate 102 such as silicone is placed on the second face member 32, and the second face member 32 is pressed from above with a press 104, applying a uniform force to the second face member 32 with a torque wrench or the like, and fixed in place with a jig or the like. At this time, the position of the mold 100 is adjusted so that the second layer 38 has a predetermined thickness. The adhesive is also made to overflow from the third layer 40 so that it covers the entire face surface 1402. As a result, the adhesive 44 located between the first layer 36 and the third layer 40 flows between the multiple second protrusions 54, filling the gap between the first layer 36 and the third layer 40 evenly, and excess adhesive 44 overflows from between the first layer 36 and the third layer 40. The overflowing excess adhesive 44 is removed from the head main body 12C. The mold 100, the first face member 30, the second face member 32, the head main body 12A, and the fixture are then placed in a heating oven and heated for a predetermined time, e.g., about one hour at 30°C to 120°C, to thermally cure the adhesive 44. Once thermal curing is complete, the mold 100 and fixture are opened, and the completed golf club head 10A is removed. As previously mentioned, an autoclave manufacturing method is also possible.

[0040] According to the third embodiment, the adhesive 44 is evenly distributed over the entire area between the first layer 36 and the third layer 40, which makes the thickness of the adhesive 44 in the second layer 38 uniform and reduces variations in the thickness of the second layer 38. This is advantageous in reducing variations in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10C.

[0041] Fourth Embodiment Next, a golf club head 10D according to a fourth embodiment will be described with reference to FIG. 18 . The thermosetting liquid adhesive is as follows. As shown in FIG. 18 , the fourth embodiment uses a plurality of spheres instead of the mesh body 42 of the first embodiment. That is, the face plate 34 constituting the first layer 36 and the second face member 32 constituting the third layer 40 are the same as those of the first embodiment. The second layer 38 is formed by curing an adhesive 44 containing a plurality of rigid spheres 56 having a uniform diameter of 0.1 mm to 0.5 mm. In other words, the second layer 38 is formed as an adhesive layer in which a plurality of rigid spheres 56 having a uniform diameter of 0.1 mm to 0.5 mm are mixed with the elastic adhesive 44. In this embodiment, the second layer 38 is formed as an adhesive layer consisting of the elastic adhesive 44 and the spheres 56. The adhesive 44 and the plurality of spheres 56 are mixed in a ratio of, for example, 4 g of adhesive 44 to 1 g of the plurality of spheres 56. Stainless steel or synthetic resin can be used as the material for the spheres 56. The spheres 56 penetrate the second layer 38 and contact the first layer 36 and the back surface of the face surface 1402 of the third layer 40. When the diameter d of the spheres 56 is within the range of 0.1 mm to 0.5 mm, the adhesive 44 flows between the spheres 56, making it easier to ensure the thickness of the adhesive 44 based on the diameter of the spheres 56. This reduces the variation in the thickness of the second layer 38, which is advantageous for reducing the variation in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10D. If the diameter d of the spheres 56 is below or above the above range, the adhesive 44 does not easily flow between the spheres 56, and it becomes difficult to ensure the thickness of the adhesive 44 based on the diameter of the spheres 56, which leads to variations in the thickness of the second layer 38 and a disadvantage in that the above-mentioned effect is reduced. In particular, if the diameter d exceeds the range, the rigidity of the face surface 1402 becomes too high, resulting in a decrease in resilience.

[0042] Fifth Embodiment Next, a golf club head 10E according to a fifth embodiment will be described with reference to FIG. 19 . As shown in FIG. 19 , the fifth embodiment uses a film-like sheet adhesive 58 instead of the mesh body 42 and adhesive 44 of the first embodiment. Film-like sheet adhesives are available in both thermosetting and thermoplastic forms. That is, the face plate 34 constituting the first layer 36 and the second face member 32 constituting the third layer 40 are the same as those in the first embodiment. The second layer 38 is formed by the hardening of the film-like sheet adhesive 58. In other words, the second layer 38 is formed by an adhesive layer made of the film-like sheet adhesive 58. Examples of sheet adhesives that can be used as the sheet adhesive 58 include a thermoplastic sheet adhesive (hot melt) that bonds CFRP and metal, and a sheet adhesive that requires heat hardening and uses a synthetic resin with a Shore A of 40 to 95.

[0043] The manufacturing method of the golf club head 10E of the fifth embodiment is as follows. The following describes the case where a thermoplastic sheet adhesive is used as the sheet adhesive 58. First, the sheet adhesive 58 that constitutes the second layer 38 is attached to the surface of the face plate 34 that constitutes the first layer 36 of the head main body 12E. The sheet adhesive 58 is pre-processed to have a contour that matches the contours of the first layer 36 and the third layer 40. Next, as shown in FIG. 24 , the second face member 32 that constitutes the third layer 40 is placed on the first layer 36 via the sheet adhesive 58, and the head main body 12E is placed in a mold 100. A resin plate 102 such as silicone is placed on the second face member 32. A press 104 is then used from above to apply a uniform force to the second face member 32, maintaining a constant pressure using a torque wrench or the like, and the second face member 32 is fixed in place using a jig or the like. At this time, the position of the mold 100 is adjusted so that the second layer 38 has a predetermined thickness. The adhesive must be allowed to overflow from the third layer 40 so that it covers the entire face surface 1402. This ensures that the sheet adhesive 58 is evenly distributed throughout the entire area between the first layer 36 and the third layer 40. The mold 100, along with the first face member 30, the second face member 32, the head main body 12A, and the fixture, are then placed in a heating oven and heated for a predetermined time, e.g., about one hour, at 30°C to 120°C, to thermally cure the adhesive 44. Once thermal curing is complete, the mold 100 and the fixture are opened, and the completed golf club head 10A is removed. As previously mentioned, an autoclave manufacturing method is also possible. When using a sheet adhesive 58 that does not require heating, the first layer 36 and the third layer 40 can be bonded together by the sheet adhesive 58 by applying pressure to the sheet adhesive 58 between the first layer 36 and the third layer 40 using the mold 100, eliminating the need for a heating oven.

[0044] According to the fifth embodiment, the sheet adhesive 58 is evenly distributed throughout the entire area between the first layer 36 and the third layer 40, thereby making the thickness of the second layer 38 uniform and reducing variations in the thickness of the second layer 38. Of course, adjustments to the pressure, temperature, jigs, etc. are required. This is advantageous in reducing variations in the high initial velocity area (sweet spot), flight distance, and durability of the golf club head 10E.

[0045] Next, experimental examples of the present invention will be described. Figures 20 to 23 are diagrams showing experimental results for golf club heads 10A-10E (hereinafter simply referred to as golf club heads 10) according to the present invention. A sample golf club head 10 was created for each experimental example, and the following five evaluation items were measured to determine indices (evaluation scores), and the total score of the five indices was calculated.

[0046] (1) Variation in High Initial Velocity Area (Sweet Area) Forty-five impact points Pi were set at equal intervals in the toe-heel and crown-sole directions around the center point Pc of the face surface 1402. A dedicated swing robot was used to swing the golf club at the 45 impact points Pi, and the initial velocity of the golf ball was measured using a measuring device. The head speed was 40 m / s. The initial velocity data from the 45 impact points was interpolated to determine the area of ​​the high initial velocity area on the face surface 1402 where the maximum initial velocity of the golf ball was 98% or more. Note that the data from impact points above the center point Pc (closer to the crown portion 16) and below the center point Pc (closer to the sole portion 18) were weighted more heavily to match the actual impact point location of the golfer, with the data from the upper impact point (closer to the crown portion 16). The area of ​​the high initial velocity area was then determined for each of the 20 samples, and the standard deviation indicating the variation was calculated. The data on the variation in the high initial velocity area is expressed as an index, with the standard deviation of the variation in the high initial velocity area of ​​the golf club head 10 of Experimental Example 1 being set to 100. The larger the index, the smaller the variation (in other words, the smaller the standard deviation) and the better the evaluation.

[0047] (2) Distance Variation A golf club equipped with the golf club head 10 was mounted on a swing robot, and a hit test was conducted under the following conditions to measure the distance at nine impact points described below. Head speed: 40 m / s Ball: PRGR RS Spin (product name) manufactured by PRGR Co., Ltd. A total of nine impact points were set as follows, and the ball was hit five times at each impact point. Three impact points were measured: the center point Pc of the face surface 140224A; a point 7 mm away from the center point Pc in the toe 2436 direction and a point 7 mm away from the center point Pc in the heel 2638 direction on a line passing through the center point Pc and perpendicular to the face center line CL; a point 5 mm away from the center point Pc on the face center line CL in the crown portion 1626 direction; and a point 7 mm away from the center point Pc in the toe 2436 direction and a point 7 mm away from the heel 2638 direction on a line 5 mm above the center point Pc and perpendicular to the face center line CL. Three impact points were measured: one on the face center line CL, 5 mm away from the center point Pc in the direction of the sole portion 1828; and one on a line 5 mm below this point, perpendicular to the face center line CL, 7 mm away from the above point in the direction of the toe 2436; and another 7 mm away from the above point in the direction of the heel 2638. The average flight distance of the nine impact points was then calculated for each of the 20 samples, and the standard deviation indicating the variation was calculated. The flight distance variation data was expressed as an index, with the standard deviation of the flight distance variation of the golf club head 10 of Experimental Example 1 being set to 100. The larger the index, the smaller the variation (in other words, the smaller the standard deviation) and the better the evaluation.

[0048] (3) Variation in Durability Golf balls were repeatedly hit with an air cannon against the face 1402 of the golf club head 10 fixed to the shaft, and the number of hits required until deformation or damage to the face portion 1424 occurred was measured to determine the number of hits. The ball speed was set to 50 m / s. The impact point was set to the center point Pc of the face 1402. The number of hits was then determined for each of the 20 samples, and a standard deviation indicating the variation was calculated. The durability variation data was expressed as an index, with the standard deviation of the durability variation of the golf club head 10 of Experimental Example 1 set to 100. The larger the index, the smaller the variation (in other words, the smaller the standard deviation) and the better the evaluation.

[0049] (4) Variation in feel on impact Fifty golfers were asked to evaluate the variability in feel on impact for the same sample using a rating scale of 10. If the feel on impact remained the same regardless of where on the face 14 the ball was hit, the rating scale was high, and if the feel on impact varied greatly depending on the location on the face 14 the rating scale was low. The average of the ratings from the 50 golfers was calculated as the average rating scale for the variability in feel on impact. The data on the variability in feel on impact was expressed as an index, with the average rating scale for the variability in feel of the golf club head 10 of Experimental Example 1 being 100. The higher the index, the smaller the variability in feel and the better the evaluation.

[0050] (5) Total Score The total score was calculated by adding up the four indices of the variation in the high initial velocity area, the variation in flight distance, the variation in durability, and the variation in hitting feel. The total score for the experimental example corresponding to the comparative example was 400, and the higher the total score, the better the evaluation.

[0051] The experimental conditions are explained below. Experimental Example 1 is a comparative example, and is a hollow driver in which the face portion 14 is composed of a first layer 36 supported by the head body 12A, a second layer 38 provided on the surface of the first layer 36 located opposite the hollow portion 22 of the head body 12A, and a third layer 40 provided on the surface of the second layer 38 located opposite the first layer 36, with the second layer 38 being composed only of hardened adhesive 44. Experimental Example 1 does not satisfy the provisions of any of claims 1 and 10-13, and is outside the scope of the present invention. The specifications of each part of Experimental Example 1 are as follows: Head body 12A material: titanium alloy Ti-8Al-1Mo-1V Face portion 14 material: titanium alloy Ti-6Al-4V Loft angle: 10.5° Lie angle: 59° Head mass: 200 g Head volume: 460 cc

[0052] The golf club head 10 used in Examples 2-30 corresponds to the present invention and is a hollow driver that satisfies the provisions of claim 1 and any of claims 10-13, and has the following common specifications except for the parameters specified in each example: Material of head body 12A: Titanium alloy Ti-8Al-1Mo-1V Loft angle 10.5° Lie angle 59° Head mass 200g Head volume 460cc

[0053] (Condition 1: Figure 20 / Experimental Examples 2-11) As shown in Figure 20, Condition 1 varied the type of mesh body 42, thickness T of mesh body 42, thickness D of fibers 48 of mesh body 42, and opening size S of mesh body 42, as defined in claims 2-4. The mesh bodies 42 of Experimental Examples 2, 3, and 5 were made of tulle 46 woven with nylon fibers, as shown in Figure 5. The nylon surface was coated with melamine resin. The mesh body 42 of Experimental Example 4 was made of glass cloth 48 plain-woven with glass fibers, as shown in Figure 4. Experimental Examples 2-11 satisfied the provisions of claim 1 and are within the scope of the present invention. Experimental Examples 5, 8, and 9 did not satisfy part of the provisions of claim 2. That is, claim 5 fell below the ranges of thickness T of mesh body 42 and thickness D of fibers 48 defined in claim 2. Claim 8 fell below the range of opening size S of mesh body 42 defined in claim 2. Claim 9 exceeds the range of opening dimensions S of the mesh body 42 defined in claim 2. Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Examples 2-11, which are within the scope of the present invention, are superior in terms of variation in the high initial velocity area, variation in flight distance, variation in durability, variation in feel on impact, and total score. Also, Experimental Examples 4, 6, 7, 10, and 11, which satisfy claim 2, are superior in terms of variation in the high initial velocity area, variation in flight distance, variation in durability, variation in feel on impact, and total score, compared to Experimental Examples 5, 8, and 9, which do not satisfy claim 2.

[0054] (Condition 2: Figure 21 / Experimental Examples 12-17) Under Condition 2, the hardness of the cured adhesive 44 as defined in claim 5 and the fill rate of the adhesive 44 in the impact area as defined in claim 6 were varied. Experimental Examples 12-17 satisfy the provisions of claims 1-4 and are within the scope of the present invention. Experimental Examples 12 and 13 do not satisfy the hardness provision defined in claim 5. That is, claims 12 and 16 are below the hardness range defined in claim 5. Claim 13 exceeds the hardness range defined in claim 5. Experimental Example 16 is below the fill rate range of the adhesive 44 in the impact area as defined in claim 6. Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Examples 12-17, which are within the scope of the present invention, are superior in terms of the variation in the high initial velocity area, the variation in flight distance, the variation in durability, the variation in feel, and the total score. Furthermore, experimental examples 14, 15, and 17, which satisfy claims 5 and 6, are superior to experimental examples 12, 13, and 16, which do not satisfy claims 5 or 6, in terms of the variation in the high initial velocity area, the variation in flight distance, the variation in durability, the variation in hitting feel, and the total score.

[0055] (Condition 3: Figure 22 / Experimental Examples 18-27) Condition 3 involves varying the thickness variation of the second layer 38 as defined in claim 7, the bending rigidity of the first layer 36 as defined in claim 8, and the bending rigidity of the third layer 40 as defined in claim 9. Experimental Examples 18-27 satisfy the requirements of claims 1-6 and are within the scope of the present invention. Experimental Example 18 exceeds the range of thickness variation of the second layer 38 as defined in claim 7. Experimental Example 20 falls below the range of bending rigidity of the third layer 40 as defined in claim 9. Experimental Example 21 exceeds the range of bending rigidity of the third layer 40 as defined in claim 9. Experimental Example 24 falls below the range of bending rigidity of the first layer 36 as defined in claim 8. Experimental Example 25 exceeds the range of bending rigidity of the first layer 36 as defined in claim 8. Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Examples 18-27, which are within the scope of the present invention, are superior in terms of variation in the high initial velocity area, variation in flight distance, variation in durability, variation in feel on impact, and total score. Also, Experimental Examples 19, 22, 23, 26, and 27, which satisfy claims 7, 8, and 9, are superior in terms of variation in the high initial velocity area, variation in flight distance, variation in durability, variation in feel on impact, and total score, compared to Experimental Examples 18, 20, 21, 24, and 25, which do not satisfy any of claims 7, 8, and 9.

[0056] (Condition 4: Figure 23 / Experimental Examples 28-30) Under Condition 4, Experimental Examples 28, 29, and 30, which satisfy claims 10, 12, and 13, are evaluated. Experimental Example 28 includes first convex portion 52, which satisfies the provisions of claim 10. Experimental Example 29 includes spheres 56 mixed into adhesive 44, which satisfies the provisions of claim 12. Experimental Example 30 includes sheet adhesive 58, which satisfies the provisions of claim 13. Therefore, compared to Experimental Example 1, which is outside the scope of the present invention, Experimental Examples 28, 29, and 30, which are within the scope of the present invention, are superior in terms of variation in high initial velocity area, variation in flight distance, variation in durability, variation in hit feel, and total score.

[0057] In this embodiment, the golf club head 10 is a hollow wood-type golf club head (driver), but the present invention is of course also applicable to hollow utilities and fairway woods.

[0058] REFERENCE SIGNS LIST 100 Golf club S Shaft 10A-10E Golf club head 12A-12E Head body 14 Face portion 1402 Face surface 16 Crown portion 18 Sole portion 20 Side portion 22 Hollow portion 24 Toe 26 Heel 28 Hosel 30 Plate-shaped first face member 32 Plate-shaped second face member 34 Face portion plate portion 36 First layer 38 Second layer 40 Third layer 41 Synthetic resin 42 Mesh body 43 Glass cloth 44 Adhesive 46 Tulle 48 Fiber 50 Mesh 52 First convex portion 54 Second convex portion 56 Sphere 58 Sheet adhesive 100 Mold 102 Resin plate 104 Press

Claims

1. A golf club head with a hollow structure in which at least a portion of the face comprises a first layer supported by the head body, a second layer provided on the surface of the first layer opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer opposite the first layer, the surface of the third layer opposite the second layer forming the face surface, wherein the second layer is composed of an adhesive layer comprising an adhesive and a mesh body in which fibers are woven or knitted into a mesh shape and are impregnated with the adhesive.

2. A golf club head according to claim 1, characterized in that the thickness T of the mesh body is 0.1 mm or more and 1.0 mm or less, the thickness D of the fibers is 0.1 mm or more and 1.0 mm or less, and the opening dimension S of the mesh body is 0.3 mm or more and 3.0 mm or less.

3. The golf club head according to claim 1, wherein the fibers are made of any one of synthetic resin, carbon resin, glass, and metal.

4. The golf club head according to claim 1, wherein the mesh body is made of tulle, which is a knitted material in which polygonal meshes are formed by weaving the fibers.

5. A golf club head according to claim 1, characterized in that the adhesive after curing has a Shore A hardness of 40 or more and 95 or less at 25°C, and the tan δ of the adhesive after curing at 25°C to 80°C is 0.05 or more and 0.4 or less.

6. The golf club head according to claim 1, wherein the adhesive contains a silyl group-terminated polymer and an organometallic catalyst necessary for the silyl groups to form a crosslinked structure through a condensation reaction.

7. The golf club head according to claim 6, wherein the terminal group of the silyl group-terminated polymer is represented by structural formula 1, and the number of the terminal groups is an average of 1.5 to 3 per polymer molecule. (Structural formula 1) (where n = 2 or 3, n + m = 3, R: CH ３ -, C ２ H ５ -, C ３ H ９ - including at least one of 8. The golf club head according to claim 5 or 6, wherein the adhesive contains, together with the silyl group-terminated polymer, an epoxy resin and an amine catalyst necessary for the epoxy resin to form a crosslinked structure by an addition reaction.

9. The golf club head according to claim 1, wherein the filling rate of the adhesive filling the mesh of the mesh body in the impact area of ​​the face portion is 95% or more and 100% or less.

10. The golf club head according to claim 1, wherein the variation in thickness of the second layer in the impact area of ​​the face portion is within ±0.15 mm, preferably within 0.1 mm.

11. The hardness of the first layer is Shore D75 or more and Vickers hardness HV520 or less, and the bending rigidity of the first layer is 8000 N mm ２ 230,000N・mm or more ２ 2. The golf club head according to claim 1, wherein the thickness of the first layer is equal to or greater than 1.0 mm and equal to or less than 6.0 mm.

12. The hardness of the third layer is Shore D75 or more and Vickers hardness HV520 or less, and the bending rigidity of the third layer is 100 N mm ２ More than 3000N・mm ２ 2. The golf club head according to claim 1, wherein the thickness of the third layer is equal to or greater than 0.2 mm and equal to or less than 2.0 mm.

13. A golf club head having a hollow structure, in which at least a portion of the face portion comprises a first layer supported by the head body, a second layer provided on the surface of the first layer located opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer located opposite the first layer, and the surface of the third layer located opposite the second layer forms the face surface, wherein the second layer is composed of an adhesive layer made of adhesive, and a plurality of cylindrical first protrusions are formed on the back surface of the third layer located opposite the face surface, passing through the adhesive layer and protruding toward the second layer and abutting the surface of the first layer facing the back surface of the third layer, the height of the first protrusions being 0.2 mm or more and 0.5 mm or less, and the diameter of the first protrusions being 0.5 mm or more and 2.0 mm or less.

14. A golf club head with a hollow structure, in which at least a portion of the face comprises a first layer supported by the head body, a second layer provided on the surface of the first layer opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer opposite the first layer, and the surface of the third layer opposite the second layer forms the face surface, wherein the second layer is composed of an adhesive layer made of adhesive, and a plurality of cylindrical second protrusions are formed on the surface of the first layer, passing through the adhesive layer and protruding toward the second layer and abutting on the back surface of the third layer opposite the surface of the first layer, the height of the second protrusions is 0.2 mm or more and 0.5 mm or less, and the diameter of the second protrusions is 0.5 mm or more and 2.0 mm or less.

15. A golf club head having a hollow structure in which at least a portion of the face comprises a first layer supported by the head body, a second layer provided on the surface of the first layer opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer opposite the first layer, the surface of the third layer opposite the second layer constituting the face surface, wherein the second layer is composed of an adhesive layer comprising an elastic adhesive and a plurality of rigid spheres having a uniform diameter of 0.1 mm to 0.5 mm mixed into the elastic adhesive.

16. A golf club head having a hollow structure in which at least a portion of the face comprises a first layer supported by the head body, a second layer provided on the surface of the first layer opposite the hollow portion of the head body, and a third layer provided on the surface of the second layer opposite the first layer, the surface of the third layer opposite the second layer constituting the face surface, wherein the second layer is composed of an adhesive layer made of a film-like sheet adhesive.

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