JP7739976B2 - Wood type golf club head - Google Patents

Description

The present invention relates to a wood-type golf club head.

Wood-type golf club heads, which have hollow head bodies, are desired to be lightweight yet have sufficient strength.

The use of fiber-reinforced plastic (FRP) is being considered to reduce the weight of wood-type golf club heads.

Japanese Patent Application Publication No. 8-117368

Patent Document 1 describes that the entire club head body, excluding the sole, is made of polyparaphenylenebenzbisoxazole fiber impregnated with resin. Patent Document 1 also describes that the club head body is made of a plate material in which prepregs aligned in one direction are laminated in the same direction.

Patent Document 1 describes how using polyparaphenylene benzbisoxazole fiber as the fiber contained in the fiber-reinforced resin results in a ball with excellent resilience, high elongation, and excellent vibration absorption when hitting the ball, improving the feel at impact.

However, the inventors have discovered that simply using polyparaphenylene benzbisoxazole fiber in the face portion makes it difficult to sufficiently increase the strength of the club head body or the flight distance of the ball. They have also discovered that the reason for this is that the characteristics of polyparaphenylene benzbisoxazole fiber cause anisotropy in the strength of the face portion and the amount of deflection upon impact.

The present invention was made based on these circumstances, and its object is to provide a wood-type golf club head that is lightweight while maintaining the strength of the head body and achieving a sufficiently large ball flight distance.

A wood-type golf club head according to one aspect of the present invention comprises a hollow head body having a face portion having a face surface, a crown portion extending rearward from the upper edge of the face portion, and a sole portion extending rearward from the lower edge of the face portion. The face portion has a first fiber-reinforced resin layer in which first fibers are dispersed in a first resin matrix, the first fibers being polyparaphenylene benzobisoxazole fibers. The first fiber-reinforced resin layer has a multi-layer structure in which fiber bundles made of a plurality of the first fibers extending in a direction parallel to the face surface are stacked in the thickness direction, the fiber bundles in each layer of the multi-layer structure having the first fibers oriented in the same direction, and the first fiber-reinforced resin layer includes two or more layers arranged so that the orientation directions of the fiber bundles between the layers differ by a predetermined angle.

Among all the first fibers contained in the first fiber-reinforced resin layer, the content of first fibers having a fiber length of 60 mm or more may be 50 mass% or more.

The first fibers preferably have a tensile strength of 4.8 GPa or more, a tensile modulus of elasticity of 200 GPa or less, and a density of 1.65 g/cm ³ or less.

The face portion may further include a second fiber-reinforced resin layer in which second fibers are dispersed in a second resin matrix.

The first fiber-reinforced resin layer may be located on the backmost surface of the face portion.

It is preferable that the thickness of the first fiber-reinforced resin layer in the face portion be 50% or more.

An opening in which the face portion is placed is provided in an area including the front edges of the crown portion and the sole portion, and the periphery of the opening is preferably made of metal.

The sole portion may be made of metal.

In the present invention, "front" refers to the side being struck, and "rear" refers to the opposite side. "Tensile strength" and "tensile modulus" refer to values determined in accordance with JIS K7073.

A wood-type golf club head according to one aspect of the present invention has a face portion including a first fiber-reinforced resin layer in which polyparaphenylenebenzbisoxazole fibers are dispersed in a first resin matrix, thereby achieving a lightweight design. The wood-type golf club head has a multilayer structure in which two or more layers of fiber bundles in which multiple polyparaphenylenebenzbisoxazole fibers are oriented in the same direction are laminated together. This multilayer structure includes two or more layers in which the orientation directions of the polyparaphenylenebenzbisoxazole fibers differ by a predetermined angle. This increases the strength and flex of the face portion while suppressing anisotropy in this strength and flex. Therefore, the wood-type golf club head increases the strength of the head body and significantly increases the flight distance of the ball.

FIG. 1 is a schematic front view of a wood-type golf club head according to an embodiment of the present invention. FIG. 2 is a schematic side view of the wood-type golf club head of FIG. 1 as viewed from the toe side. FIG. 3 is a cross-sectional view of the wood-type golf club head of FIG. 1 taken along line III-III. FIG. 4 is a schematic front view showing the wood golf club head of FIG. 1 with the face portion removed. FIG. 5 is a schematic diagram showing the first fiber reinforced resin layer of the wood golf club head of FIG. FIG. 6 is a diagram illustrating the orientation direction of the first fibers in the first fiber-reinforced resin layer of the face portion of FIG. FIG. 7 is a cross-sectional view corresponding to FIG. 3 of a wood-type golf club head in a configuration different from that of the wood-type golf club head of FIG.

Embodiments of the present invention will be described in detail below, with reference to the drawings as appropriate. It should be noted that with respect to the numerical values described in this specification, it is possible to adopt only one of the stated upper and lower limit values, or to arbitrarily combine the upper and lower limit values. In this specification, all combinable numerical ranges are considered to be preferred ranges.

[First embodiment]
<Wood type golf club head>
The wood-type golf club head 1 shown in Figures 1 to 3 includes a hollow head body 10. The head body 10 includes a face portion 2 having a face surface 2a, a crown portion 3 extending rearward from the upper edge of the face portion 2, and a sole portion 4 extending rearward from the lower edge of the face portion 2. The face surface 2a constitutes the striking surface of the wood-type golf club head 1. The head body 10 also includes side portions 5 extending rearward from a pair of left and right side edges of the face portion 2 and positioned between the crown portion 3 and the sole portion 4. The wood-type golf club head 1 is used as, for example, a driver, a utility, a fairway wood, etc. In particular, the wood-type golf club head 1 is preferably used as a driver.

(Face part)
As shown in Figure 4, the head body 10 has an opening 10a in a region including the front edges of the crown portion 3 and the sole portion 4. The face portion 2 is disposed so as to close this opening 10a. The face portion 2 is fixed to the crown portion 3 and the sole portion 4, for example, with an adhesive. The lower limit of the thickness of the face portion 2 is not particularly limited, but is preferably, for example, 2 mm, and more preferably 3 mm. The upper limit of the thickness of the face portion 2 is not particularly limited, but is preferably, for example, 5 mm, and more preferably 4 mm.

As shown in Figures 3 and 5, the face portion 2 has a first fiber-reinforced resin layer 11 in which first fibers 11a are dispersed in a first resin matrix 11b. Also, as shown in Figure 3, the face portion 2 has a second fiber-reinforced resin layer 12 in which second fibers are dispersed in a second resin matrix. The face portion 2 is made up of a laminate of multiple fiber-reinforced resin layers, including the first fiber-reinforced resin layer 11 and the second fiber-reinforced resin layer 12. More specifically, the face portion 2 has a two-layer structure made up of the first fiber-reinforced resin layer 11 and the second fiber-reinforced resin layer 12.

[First fiber reinforced resin layer]
The first fibers 11a are polyparaphenylenebenzbisoxazole (PBO) fibers. The first fiber-reinforced resin layer 11 has a multilayer structure in which fiber bundles 14 made of a plurality of first fibers 11a extending in a direction parallel to the face surface 2a are stacked in the thickness direction (thickness direction of the first fiber-reinforced resin layer 11). As shown in Figure 6, in the fiber bundles 14 in each layer 110 of the multilayer structure, the first fibers 11a are oriented in the same direction.

As shown in Figure 6, the first fiber-reinforced resin layer 11 includes two or more layers (layers 110-1 to 110-n) in which the orientation directions of the fiber bundles 14 (the orientation directions of the first fibers 11a contained in the fiber bundles 14) between the layers differ by a predetermined angle. The orientation angle between the fiber bundles 14 between the layers is not particularly limited and can be set appropriately depending on the number of layers n. For example, by increasing the number of layers n and decreasing the orientation angle, it is easier to suppress variations in strength within the plane of the first fiber-reinforced resin layer 11.

The first fiber-reinforced resin layer 11 preferably includes two or more layers 110 in which the orientation directions of the fiber bundles 14 are arranged so that they are equiangularly spaced apart overall. "Includes two or more layers in which the orientation directions of the fiber bundles 14 are arranged so that they are equiangularly spaced apart overall" means that in any two or more layers, the orientation directions of the fiber bundles 14 are varied by the same angle so that the fiber bundles 14 intersect at equiangular angles overall in a plan view (viewed in the thickness direction of the first fiber-reinforced resin layer) to reduce in-plane strength variations. For example, the first fiber-reinforced resin layer 11 may include two layers 110 in which the orientation directions of the fiber bundles 14 are orthogonal, four layers 110 in which the fiber bundles 14 intersect at 45° intervals, or eight layers 110 in which the fiber bundles 14 intersect at 22.5° intervals. Furthermore, "equal angles" preferably refers to strictly equiangular angles, but there is a tolerance of ±3°. Each layer 110 constituting the first fiber-reinforced resin layer 11 has the greatest strength in the orientation direction of the first fibers 11a. In other words, each layer 110 constituting the first fiber-reinforced resin layer 11 has strength anisotropy corresponding to the orientation direction of the first fibers 11a. In this regard, the wood-type golf club head 1 includes two or more layers 110 in which the orientation directions of the fiber bundles 14 are arranged so that they differ at equal angles overall. This makes it possible to suppress anisotropy in the strength of the face portion 2 and the amount of deflection upon impact when PBO fibers are used as the first fibers 11a.

The lower limit of the number n of layers 110, in which the orientation directions of the first fibers 11a are arranged so that they vary at equal angles overall, is preferably 4, and more preferably 8. If the number of layers is less than the lower limit, the strength of the face portion 2 and the effect of suppressing anisotropy in the amount of deflection upon impact may be insufficient. The upper limit of the number of layers is not particularly limited, but can be set to 50, for example.

The first fiber-reinforced resin layer 11 is preferably arranged so that the orientation directions of the fiber bundles 14 that make up all of the layers 110 are equiangularly different overall. This configuration makes it possible to easily and reliably prevent anisotropy from occurring in the strength of the face portion 2 and the amount of deflection upon impact.

Of all the first fibers 11a contained in the first fiber-reinforced resin layer 11, the content of first fibers 11a having a fiber length of 60 mm or more is preferably 50% by mass or more. Furthermore, the lower limit of this content is more preferably 60% by mass. As described above, the multiple first fibers 11a contained in the first fiber-reinforced resin layer 11 extend parallel to the face surface 2a. In this configuration, as shown in FIG. 5 , by increasing the length of each first fiber 11a so that they extend from edge to edge of the face portion 2 and controlling the area of the face portion 2 itself, the content of first fibers 11a having a fiber length of 60 mm or more in the first fiber-reinforced resin layer 11 can be controlled to be equal to or greater than the lower limit. If the content is less than the lower limit, the length of the first fibers 11a cannot be sufficiently increased, which may make it difficult to sufficiently increase both the strength of the face portion 2 and the amount of deflection upon impact.

As shown in FIG. 1, the lower limit of the toe-heel direction length L of the face portion 2 is preferably 70 mm, and more preferably 75 mm. Also, as shown in FIG. 2, the lower limit of the height H of the face portion 2 is preferably 40 mm, and more preferably 45 mm. By setting the face portion 2 to this size, it is easier to control the length of the first fibers 11a in the first fiber-reinforced resin layer 11 within the above range. Note that the "toe-heel direction" refers to the horizontal direction perpendicular to the front-to-back direction when the golf club head is placed on a horizontal plane to achieve a predetermined lie angle and loft angle. Also, the "height of the face portion" refers to the height of the face portion in a projection image obtained by projecting the face portion onto a plane perpendicular to an imaginary line passing through the center of gravity of the head body and the projection point of this center of gravity perpendicularly projected onto the face surface.

The lower limit of the tensile strength of the first fibers 11a is preferably 4.8 GPa, and more preferably 5.2 GPa. If the tensile strength is less than this lower limit, the durability of the first fiber-reinforced resin layer 11 during impact may be insufficient. On the other hand, the upper limit of the tensile strength is not particularly limited, but can be set to 6.2 GPa in order to ensure the flexibility of the first fiber-reinforced resin layer 11.

The upper limit of the tensile modulus of the first fibers 11a is preferably 200 GPa, and more preferably 190 GPa. If the tensile modulus exceeds this upper limit, the amount of deflection upon impact may not be sufficiently large. On the other hand, the lower limit of the tensile modulus is not particularly limited, but can be set to 120 GPa from the perspective of easily ensuring the strength of the first fiber-reinforced resin layer 11.

The upper limit of the density of the first fibers 11a is preferably 1.65 g/ ^cm3 , and more preferably 1.55 g/ ^cm3 . If the density exceeds the upper limit, it may be difficult to sufficiently reduce the weight of the face portion 2. On the other hand, the lower limit of the density is not particularly limited, but may be set to 1.40 g/ ^cm3 from the viewpoint of easily ensuring the strength of the first fiber reinforced resin layer 11.

The first fibers 11a preferably have a tensile strength, tensile modulus, and density that fall within the above ranges. This configuration makes it easier to reduce the weight of the face portion 2 while improving the strength of the face portion 2 and the amount of deflection upon impact.

The first fiber-reinforced resin layer 11 is formed by laminating multiple prepregs, each of which has multiple first fibers 11a oriented in the same direction dispersed in a first resin matrix 11b, so that the orientation directions of the first fibers 11a intersect. Examples of the main component of the first resin matrix 11b include thermosetting resins such as epoxy resins and unsaturated polyesters, and thermoplastic resins such as polyolefins and polyamides. The term "main component" refers to the component with the largest content by mass, e.g., a component with a content of 50% by mass or more.

The first fiber-reinforced resin layer 11 is located on the backside of the face portion 2. With this configuration, by placing the PBO fibers on the backside of the face portion 2, which is most susceptible to tensile stress upon impact, the strength of the face portion 2 is increased while also making it easier to sufficiently improve the amount of deflection upon impact.

The lower limit of the thickness of the first fiber-reinforced resin layer 11 in the face portion 2 is preferably 50%, and more preferably 60%. If the thickness is less than this lower limit, it may be difficult to sufficiently increase both the strength of the face portion 2 and the amount of deflection upon impact.

The upper limit of the thickness of the first fiber-reinforced resin layer 11 in the face portion 2 is not particularly limited and can be any value less than 100%, for example, 95%. Because the first fiber-reinforced resin layer 11 contains PBO fibers, polishing the surface of the first fiber-reinforced resin layer 11 may cause the PBO fibers to fluff. This may result in a loss of aesthetic appeal for the face portion 2 or make it difficult to form the face portion 2 to the desired strength. From this perspective, in this embodiment, the second fiber-reinforced resin layer 12 is laminated on the face surface 2a side of the first fiber-reinforced resin layer 11 to prevent the first fiber-reinforced resin layer 11 from being exposed to the face surface 2a.

[Second fiber reinforced resin layer]
The second fiber-reinforced resin layer 12 has a plurality of second fibers dispersed in a second resin matrix. The wood-type golf club head 1 has the second fiber-reinforced resin layer 12 in addition to the first fiber-reinforced resin layer 11, which makes it easy to control the quality of the entire face portion 2. In particular, the second fiber-reinforced resin layer 12 prevents the first fiber-reinforced resin layer 11 from being exposed to the face surface 2a, which makes it easy to control the physical properties of the entire face portion 2 while suppressing deterioration in appearance due to fluffing of the PBO fibers.

The second fiber is not particularly limited, and examples include carbon fiber and glass fiber. When the second fiber is carbon fiber, the second fiber reinforced resin layer 12 is configured as a carbon fiber reinforced resin layer (CFRP layer). When the fiber is glass fiber, the second fiber reinforced resin layer 12 is configured as a glass fiber reinforced resin layer (GFRP layer). Examples of the main component of the second resin matrix include thermosetting resins such as epoxy resin and unsaturated polyester, and thermoplastic resins such as polyolefin and polyamide. The second fiber reinforced resin layer 12 is formed, for example, by laminating multiple layers of prepreg in which the multiple second fibers are dispersed in the second resin matrix.

The first fiber-reinforced resin layer 11 and the second fiber-reinforced resin layer 12 may be laminated by fusing the first resin matrix 11b and the second resin matrix, or may be laminated using an adhesive or the like.

The lower limit of the resilience coefficient of the face portion 2 is preferably 0.820, and more preferably 0.825. If the resilience coefficient is less than the lower limit, it may not be possible to achieve a sufficiently long ball flight distance. Note that the "resilience coefficient of the face portion" refers to the value at the sweet spot, where the center of gravity of the head body is projected vertically onto the face surface, and this resilience coefficient is measured using the Cannon test recommended by the R&A.

As shown in FIG. 4, the head body 10 has an opening 10a in which the face portion 2 is disposed in a region including the front edges of the crown portion 3 and the sole portion 4. The periphery of this opening 10a is preferably made of metal. In other words, as shown in FIG. 1, the head body 10 has an annular frame portion 13 that is disposed contiguous with the periphery 2b of the face portion 2 so as to surround this periphery 2b, and this frame portion 13 is preferably made of metal. This configuration allows the periphery 2b of the face portion 2 to be supported by the metal frame portion 13, thereby allowing the face portion 2 to bend in a concentrated manner. As a result, the flight distance of the ball can be increased. Furthermore, even in this wood-type golf club head 1, even in a configuration in which the face portion 2 is bent in a concentrated manner, the first fiber-reinforced resin layer 11 has two or more layers 110 in which the orientation directions of the fiber bundles 14 are arranged at equal angles to each other overall. This increases the strength of the face portion 2 and suppresses cracking of the face portion 2. Examples of metals that can be used to form the frame 13 include titanium, stainless steel, maraging steel, aluminum, and magnesium. In the present invention, the term "metal" includes alloys.

(Crown part)
The front edge of the crown portion 3 constitutes a part of the frame portion 13. Therefore, the front edge of the crown portion 3 is made of metal. On the other hand, the material of the crown portion 3 other than the frame portion 13 is not particularly limited. For example, the entire crown portion 3 may be made of metal, or may have a portion made of fiber-reinforced resin.

(Sole)
The front edge of the sole portion 4 constitutes a part of the frame portion 13 described above. Therefore, the front edge of the sole portion 4 is made of metal. On the other hand, the material of the sole portion 4 other than the frame portion 13 is not particularly limited. For example, the sole portion 4 may have a portion made of fiber reinforced resin. However, it is preferable that the sole portion 4 is made of metal in its entirety as well, other than the frame portion 13. In other words, it is preferable that the entire sole portion 4 is made of metal. By making the sole portion 4 of metal, the strength of the sole portion 4 can be sufficiently increased, and cracking of the head body 10 during impact, etc. can be more reliably suppressed.

When the sole portion 4 is made of metal, examples of metals that make up the sole portion 4 include titanium, stainless steel, maraging steel, aluminum, and magnesium. Among these, titanium is preferred because it is lightweight and can provide sufficient strength to the sole portion 4.

<Advantages>
The wood-type golf club head 1 has a face portion 2 including a first fiber-reinforced resin layer 11 in which PBO fibers are dispersed in a first resin matrix 11b, thereby achieving a lightweight design. The wood-type golf club head 1 has a multilayer structure in which two or more fiber bundles 14 in which a plurality of PBO fibers are oriented in the same direction are stacked. This multilayer structure includes two or more layers 110 in which the orientation directions of the PBO fibers differ by a predetermined angle. This increases the strength and deflection of the face portion 2 while suppressing anisotropy in the strength and deflection. Therefore, the wood-type golf club head 1 increases the strength of the head body 10 and can sufficiently increase the flight distance of a hit ball. More specifically, suppressing anisotropy in the strength of the face portion 2 can suppress cracking of the face portion 2, and increasing the restitution coefficient of the face portion 2 can sufficiently increase the flight distance of a hit ball.

[Second embodiment]
<Wood type golf club head>
The wood-type golf club head 21 of Fig. 7 includes a hollow head body 20. The head body 20 includes a face portion 22 having a face surface 22a, a crown portion 3 extending rearward from the upper edge of the face portion 22, and a sole portion 4 extending rearward from the lower edge of the face portion 22. The face surface 22a forms the striking surface of the wood-type golf club head 21. The configuration of the wood-type golf club head 21 other than the face portion 22 can be the same as that of the wood-type golf club head 1 of Figs. 1 to 3. Therefore, only the face portion 22 will be described below.

(Face part)
The face portion 22 has a first fiber-reinforced resin layer 23 in which first fibers are dispersed in a first resin matrix. The first fibers are PBO fibers. The face portion 22 does not include any other fiber-reinforced resin layers other than the first fiber-reinforced resin layer 23. The specific configuration of the first fiber-reinforced resin layer 23 can be the same as that of the first fiber-reinforced resin layer 11 of the wood-type golf club head 1 shown in FIGS. 1 to 3 .

The face portion 22 may be composed of only the first fiber-reinforced resin layer 23. Alternatively, the face portion 22 may be configured so that the first fiber-reinforced resin layer 23 is not exposed on the face surface 22a. By not exposing the first fiber-reinforced resin layer 23 on the face surface 22a, deterioration in quality due to fluffing of the PBO fibers can be suppressed. An example of a configuration in which the first fiber-reinforced resin layer 23 is not exposed on the face surface 22a is a configuration in which a metal vapor deposition film is formed on the surface of the first fiber-reinforced resin layer 23.

<Advantages>
The wood-type golf club head 21 can be made lighter because the face portion 22 has the first fiber-reinforced resin layer 23. Furthermore, the wood-type golf club head 21 can increase the strength and deflection of the face portion 22 while suppressing anisotropy in the strength and deflection because the face portion 22 has the first fiber-reinforced resin layer 23. Therefore, the wood-type golf club head 21 can increase the strength of the head body 20 and can sufficiently increase the flight distance of the ball.

[Other embodiments]
The above-described embodiments do not limit the configuration of the present invention. Therefore, the above-described embodiments may include omissions, substitutions, or additions of components based on the description in this specification and common general technical knowledge, and all of these should be construed as falling within the scope of the present invention.

For example, the face portion may have a third fiber-reinforced resin layer other than the first fiber-reinforced resin layer and the second fiber-reinforced resin layer. In this case, the type of third fiber contained in the third fiber-reinforced resin layer is not particularly limited. Furthermore, the arrangement of the third fiber-reinforced resin layer is not particularly limited; for example, it may be arranged on the outermost surface of the face portion, or it may be arranged between the first fiber-reinforced resin layer and the second fiber-reinforced resin layer. In addition, the face portion may further have one or more fiber-reinforced resin layers other than the third fiber-reinforced resin layer.

As mentioned above, it is preferable that the first fiber-reinforced resin layer be disposed on the backside of the face portion of the wood-type golf club head, which is most susceptible to tensile stress upon impact. However, depending on the quality required of the wood-type golf club head, it is also possible to adopt a configuration in which the first fiber-reinforced resin layer is not disposed on the backside of the face portion.

As mentioned above, in the wood-type golf club head, the periphery of the opening in which the face portion is disposed is preferably made of metal. However, depending on the quality required of the wood-type golf club head, it is also possible to form part or all of the periphery of the opening from a material other than metal.

As described above, the wood-type golf club head according to one aspect of the present invention is suitable for achieving a lightweight design while also providing sufficient strength for the head body and increasing the distance the ball can be hit.

1, 21 Wood-type golf club head 2, 22 Face portion 2a, 22a Face surface 2b Periphery 3 Crown portion 4 Sole portion 5 Side portion 10, 20 Head body 10a Opening 11, 23 First fiber reinforced resin layer 11a First fibers 11b First resin matrix 12 Second fiber reinforced resin layer 13 Frame portion 14 Fiber bundle 110 Layer H Height of face portion L Length of face portion in toe-heel direction

Claims (7)

a hollow head body having a face portion having a face surface, a crown portion extending rearward from an upper edge of the face portion, and a sole portion extending rearward from a lower edge of the face portion;
the face portion has a first fiber reinforced resin layer in which first fibers are dispersed in a first resin matrix,
the first fiber is a polyparaphenylene benzbisoxazole fiber,
the first fiber reinforced resin layer has a multilayer structure in which fiber bundles made of a plurality of the first fibers extending in a direction parallel to the face surface are stacked in a thickness direction,
In the fiber bundles in each layer of the multilayer structure, the first fibers are oriented in the same direction,
The first fiber reinforced resin layer includes two or more layers arranged so that the orientation directions of the fiber bundles between the layers differ by a predetermined angle ,
The first fiber reinforced resin layer is located on the back surface of the face portion,
an opening in which the face portion is disposed is provided in a region including front edges of the crown portion and the sole portion, a peripheral portion of the opening is made of metal, and the first fiber reinforced resin layer is directly fixed to the crown portion and the sole portion with an adhesive so as to close the opening;
A wood-type golf club head , wherein the length of the face portion in the toe-heel direction is 70 mm or more, and the height of the face portion is 40 mm or more . 2. The wood-type golf club head according to claim 1, wherein the face portion has a restitution coefficient of 0.820 or more. 3. The wood-type golf club head according to claim 1 , wherein the first fiber reinforced resin layer contains 50% by mass or more of all the first fibers having a fiber length of 60 mm or more. 4. The wood-type golf club head according to claim 1, wherein the first fibers have a tensile strength of 4.8 GPa or more, a tensile modulus of elasticity of 200 GPa or less, and a density of 1.65 g/cm ^<3> or less. 5. The wood-type golf club head according to claim 1 , wherein the face portion further comprises a second fiber-reinforced resin layer in which second fibers are dispersed in a second resin matrix. 6. The wood-type golf club head according to claim 5, wherein the thickness of the first fiber-reinforced resin layer in the face portion is 50% or more. 7. The wood-type golf club head according to claim 1 , wherein the sole portion is made of metal.